Methods for treating skin disorders by local administration of a Clostridial toxin, such as a botulinum toxin, to a patient with a skin disorder.

The present invention relates to methods for treating skin disorders. In particular the present invention relates to methods for treating skin disorders by administration of a Clostridial neurotoxin to a patient.
Skin Disorders
The skin (synonymously the cutis) is a protective membrane which covers the body and is composed of several layers including the epidermis and the cornium. A skin disorder is an anomaly or an abnormal skin growth and can appear at any cutis location, such as on a hand, foot or face of a patient. Some skin disorders are more prevalent at pressure, wear or weight bearing locations, such as on the feet. A skin disorder can be a wart, bunion, callus, corn, ulcer, neuroma, hammertoe, dermatofibroma, keloid, mole (such as a typical mole or dysplastic nevi), granuloma (such as a pyogenic granuloma) and a keratose (such as a seborrheic keratose).
A bunion is a localized swelling at either the medial or dorsal aspect of the first metarsophalangeal joint of the foot and can be caused by an inflamed bursa. A bursa is a closed fluid filled sac that can form in an area subject to friction. A bunion can be due to hallux valgus which is a deviation of the tip of the big toe toward the outside of the foot. This can cause the first metatarsal and the big toe to form an aberrant leftward angle. A bunion can then develop in response to the pressure from a tight fitting shoe at the point of this angle.
A callus is a protective cutis pad made up of a thickened upper layer of skin which forms due to repeated rubbing of the skin at that location. A corn is a small callus which develops on the top of the toes due to pressure or rubbing against shoes or other toes. A corn can also develop due to a hammertoe condition which is an abnormal contraction or buckling of the toe because of a partial or complete dislocation of one of the joints of the toe or the joint where the toe joins with the rest of the foot. As the toe becomes deformed, it can rub against a shoe and the resulting irritation can cause the build up of more and thicker skin (a corn) as a protective response at that cutis location.
An ulcer is a slow healing skin wound. A stage one ulcer is characterized by reddening of skin over a bony area. The redness on the skin does not go away when the pressure is relieved. A stage two ulcer is characterized by a blister, peeling or cracked skin. There is a partial thickness skin loss involving the top two layers of the skin. A stage three ulcer exhibits broken skin and sometimes a bloody drainage. There is a full thickness skin loss involving subcutaneous tissue. Finally, a stage four ulcer is characterized by a break in the skin involving skin, muscle, tendon and bone and is often associated with a bone infection (osteomyelitis). Ulcers can be debilitating and painful.
Warts are non-cancerous skin growths caused by infection in the top layer of the skin by a papillomavirus. Warts are usually skin-colored and may feel rough to the touch, but they can be dark, flat and smooth. There are several different kinds of warts including common warts, foot (plantar) warts and flat warts. A plantar wart is a small skin lesion that resembles a callus and is found on the bottom of the foot or toes.
A neuroma is a swelling or scarring of a small nerve that connects to two toes and provides sensation to these toes. Symptoms of a neuroma can include pain or numbness, usually affecting the third and fourth toes. Neuromas frequently start as a numbness or tenderness in the ball of the foot.
Current therapies for skin disorders includes use of various topical and systemic pharmaceuticals and/or surgery to excise the disorder. Pharmaceuticals typically have unwanted side effects and there can unfortunately be a significant reoccurrence of the skin disorder (regrowth) after surgery, as well as the possibly of infection.
Botulinum Toxin
The genus Clostridium has more than one hundred and twenty seven species, grouped according to their morphology and functions. The anaerobic, gram positive bacterium Clostridium botulinum produces a potent polypeptide neurotoxin, botulinum toxin, which causes a neuroparalytic illness in humans and animals referred to as botulism. The spores of Clostridium botulinum are found in soil and can grow in improperly sterilized and sealed food containers of home based canneries, which are the cause of many of the cases of botulism. The effects of botulism typically appear 18 to 36 hours after eating the foodstuffs infected with a Clostridium botulinum culture or spores. The botulinum toxin can apparently pass unattenuated through the lining of the gut and attack peripheral motor neurons. Symptoms of botulinum toxin intoxication can progress from difficulty walking, swallowing, and speaking to paralysis of the respiratory muscles and death.
Botulinum toxin type A is the most lethal natural biological agent known to man. About 50 picograms of a commercially available botulinum toxin type A (purified neurotoxin complex) 1 is a LD50 in mice (i.e. 1 unit). One unit of BOTOX® contains about 50 picograms (about 56 attomoles) of botulinum toxin type A complex. Interestingly, on a molar basis, botulinum toxin type A is about 1.8 billion times more lethal than diphtheria, about 600 million times more lethal than sodium cyanide, about 30 million times more lethal than cobra toxin and about 12 million times more lethal than cholera. Singh, Critical Aspects of Bacterial Protein Toxins, pages 63-84 (chapter 4) of Natural Toxins II, edited by B. R. Singh et al., Plenum Press, New York (1976) (where the stated LD50 of botulinum toxin type A of 0.3 ng equals 1 U is corrected for the fact that about 0.05 ng of BOTOX® equals 1 unit). One unit (U) of botulinum toxin is defined as the LD50 upon intraperitoneal injection into female Swiss Webster mice weighing 18 to 20 grams each.
Seven generally immunologically distinct botulinum neurotoxins have been characterized, these being respectively botulinum neurotoxin serotypes A, B, C1, D, E, F and G each of which is distinguished by neutralization with type-specific antibodies. The different serotypes of botulinum toxin vary in the animal species that they affect and in the severity and duration of the paralysis they evoke. For example, it has been determined that botulinum toxin type A is 500 times more potent, as measured by the rate of paralysis produced in the rat, than is botulinum toxin type B. Additionally, botulinum toxin type B has been determined to be non-toxic in primates at a dose of 480 U/kg which is about 12 times the primate LD50 for botulinum toxin type A. Moyer E et al., Botulinum Toxin Type B: Experimental and Clinical Experience, being chapter 6, pages 71-85 of "Therapy With Botulinum Toxin", edited by Jankovic, J. et al. (1994), Marcel Dekker, Inc. Botulinum toxin apparently binds with high affinity to cholinergic motor neurons, is translocated into the neuron and blocks the release of acetylcholine. Additional uptake can take place through low affinity receptors, as well as by phagocytosis and pinocytosis.
Regardless of serotype, the molecular mechanism of toxin intoxication appears to be similar and to involve at least three steps or stages. In the first step of the process, the toxin binds to the presynaptic membrane of the target neuron through a specific interaction between the heavy chain, H chain, and a cell surface receptor; the receptor is thought to be different for each type of botulinum toxin and for tetanus toxin. The carboxyl end segment of the H chain, HC, appears to be important for targeting of the toxin to the cell surface.
In the second step, the toxin crosses the plasma membrane of the poisoned cell. The toxin is first engulfed by the cell through receptor-mediated endocytosis, and an endosome containing the toxin is formed. The toxin then escapes the endosome into the cytoplasm of the cell. This step is thought to be mediated by the amino end segment of the H chain, HN, which triggers a conformational change of the toxin in response to a pH of about 5.5 or lower. Endosomes are known to possess a proton pump which decreases intra-endosomal pH. The conformational shift exposes hydrophobic residues in the toxin, which permits the toxin to embed itself in the endosomal membrane. The toxin (or at a minimum the light chain) then translocates through the endosomal membrane into the cytoplasm.
The last step of the mechanism of botulinum toxin activity appears to involve reduction of the disulfide bond joining the heavy chain, H chain, and the light chain, L chain. The entire toxic activity of botulinum and tetanus toxins is contained in the L chain of the holotoxin; the L chain is a zinc (Zn++) endopeptidase which selectively cleaves proteins essential for recognition and docking of neurotransmitter-containing vesicles with the cytoplasmic surface of the plasma membrane, and fusion of the vesicles with the plasma membrane. Tetanus neurotoxin, botulinum toxin types B, D, F, and G cause degradation of synaptobrevin (also called vesicle-associated membrane protein (VAMP)), a synaptosomal membrane protein. Most of the VAMP present at the cytoplasmic surface of the synaptic vesicle is removed as a result of any one of these cleavage events. Botulinum toxin serotype A and E cleave SNAP-25. Botulinum toxin serotype C1 was originally thought to cleave syntaxin, but was found to cleave syntaxin and SNAP-25. Each of the botulinum toxins specifically cleaves a different bond, except botulinum toxin type B (and tetanus toxin) which cleave the same bond. Each of these cleavages block the process of vesicle-membrane docking, thereby preventing exocytosis of vesicle content.
Botulinum toxins have been used in clinical settings for the treatment of neuromuscular disorders characterized by hyperactive skeletal muscles (i.e. motor disorders). In 1989 a botulinum toxin type A complex has been approved by the U.S. Food and Drug Administration for the treatment of blepharospasm, strabismus and hemifacial spasm. Subsequently, a botulinum toxin type A was also approved by the FDA for the treatment of cervical dystonia and for the treatment of glabellar lines, and a botulinum toxin type B was approved for the treatment of cervical dystonia. Non-type A botulinum toxin serotypes apparently have a lower potency and/or a shorter duration of activity as compared to botulinum toxin type A. Clinical effects of peripheral intramuscular botulinum toxin type A are usually seen within one week of injection. The typical duration of symptomatic relief from a single intramuscular injection of botulinum toxin type A averages about three months, although significantly longer periods of therapeutic activity have been reported.
Although all the botulinum toxins serotypes apparently inhibit release of the neurotransmitter acetylcholine at the neuromuscular junction, they do so by affecting different neurosecretory proteins and/or cleaving these proteins at different sites. For example, botulinum types A and E both cleave the 25 kiloDalton (kD) synaptosomal associated protein (SNAP-25), but they target different amino acid sequences within this protein. Botulinum toxin types B, D, F and G act on vesicle-associated protein (VAMP, also called synaptobrevin), with each serotype cleaving the protein at a different site. Finally, botulinum toxin type C1 has been shown to cleave both syntaxin and SNAP-25. These differences in mechanism of action may affect the relative potency and/or duration of action of the various botulinum toxin serotypes. Apparently, a substrate for a botulinum toxin can be found in a variety of different cell types. See e.g. Biochem J 1; 339 (pt 1):159-65:1999, and Mov Disord, 10(3):376:1995 (pancreatic islet B cells contains at least SNAP-25 and synaptobrevin).
The molecular weight of the botulinum toxin protein molecule, for all seven of the known botulinum toxin serotypes, is about 150 kD. Interestingly, the botulinum toxins are released by Clostridial bacterium as complexes comprising the 150 kD botulinum toxin protein molecule along with associated non-toxin proteins. Thus, the botulinum toxin type A complex can be produced by Clostridial bacterium as 900 kD, 500 kD and 300 kD forms. Botulinum toxin types B and C1 is apparently produced as only a 700 kD or 500 kD complex. Botulinum toxin type D is produced as both 300 kD and 500 kD complexes. Finally, botulinum toxin types E and F are produced as only approximately 300 kD complexes. The complexes (i.e. molecular weight greater than about 150 kD) are believed to contain a non-toxin hemaglutinin protein and a non-toxin and non-toxic nonhemaglutinin protein. These two non-toxin proteins (which along with the botulinum toxin molecule comprise the relevant neurotoxin complex) may act to provide stability against denaturation to the botulinum toxin molecule and protection against digestive acids when toxin is ingested. Additionally, it is possible that the larger (greater than about 150 kD molecular weight) botulinum toxin complexes may result in a slower rate of diffusion of the botulinum toxin away from a site of intramuscular injection of a botulinum toxin complex.
In vitro studies have indicated that botulinum toxin inhibits potassium cation induced release of both acetylcholine and norepinephrine from primary cell cultures of brainstem tissue. Additionally, it has been reported that botulinum toxin inhibits the evoked release of both glycine and glutamate in primary cultures of spinal cord neurons and that in brain synaptosome preparations botulinum toxin inhibits the release of each of the neurotransmitters acetylcholine, dopamine, norepinephrine (Habermann E., et al., Tetanus Toxin and Botulinum A and C Neurotoxins Inhibit Noradrenaline Release From Cultured Mouse Brain, J Neurochem 51(2); 522-527:1988) CGRP, substance P and glutamate (Sanchez-Prieto, J., et al., Botulinum Toxin A Blocks Glutamate Exocytosis From Guinea Pig Cerebral Cortical Synaptosomes, Eur J. Biochem 165; 675-681:1897. Thus, when adequate concentrations are used, stimulus-evoked release of most neurotransmitters is blocked by botulinum toxin. See e.g. Pearce, L. B., Pharmacologic Characterization of Botulinum Toxin For Basic Science and Medicine, Toxicon 35(9); 1373-1412 at 1393; Bigalke H., et al., Botulinum A Neurotoxin Inhibits Non-Cholinergic Synaptic Transmission in Mouse Spinal Cord Neurons in Culture, Brain Research 360; 318-324:1985; Habermann E., Inhibition by Tetanus and Botulinum A Toxin of the release of [3H]Noradrenaline and [3H]GABA From Rat Brain Homogenate, Experientia 44; 224-226:1988, Bigalke H., et al., Tetanus Toxin and Botulinum A Toxin Inhibit Release and Uptake of Various Transmitters, as Studied with Particulate Preparations From Rat Brain and Spinal Cord, Naunyn-Schmiedeberg's Arch Pharmacol 316; 244-251:1981, and; Jankovic J. et al., Therapy With Botulinum Toxin, Marcel Dekker, Inc., (1994), page 5.
Botulinum toxin type A can be obtained by establishing and growing cultures of Clostridium botulinum in a fermenter and then harvesting and purifying the fermented mixture in accordance with known procedures. All the botulinum toxin serotypes are initially synthesized as inactive single chain proteins which must be cleaved or nicked by proteases to become neuroactive. The bacterial strains that make botulinum toxin serotypes A and G possess endogenous proteases and serotypes A and G can therefore be recovered from bacterial cultures in predominantly their active form. In contrast, botulinum toxin serotypes C1, D and E are synthesized by nonproteolytic strains and are therefore typically unactivated when recovered from culture. Serotypes B and F are produced by both proteolytic and nonproteolytic strains and therefore can be recovered in either the active or inactive form. However, even the proteolytic strains that produce, for example, the botulinum toxin type B serotype only cleave a portion of the toxin produced. The exact proportion of nicked to unnicked molecules depends on the length of incubation and the temperature of the culture. Therefore, a certain percentage of any preparation of, for example, the botulinum toxin type B toxin is likely to be inactive, possibly accounting for the known significantly lower potency of botulinum toxin type B as compared to botulinum toxin type A. The presence of inactive botulinum toxin molecules in a clinical preparation will contribute to the overall protein load of the preparation, which has been linked to increased antigenicity, without contributing to its clinical efficacy. Additionally, it is known that botulinum toxin type B has, upon intramuscular injection, a shorter duration of activity and is also less potent than botulinum toxin type A at the same dose level.
High quality crystalline botulinum toxin type A can be produced from the Hall A strain of Clostridium botulinum with characteristics of >3×107 U/mg, an A260/A278 of less than 0.60 and a distinct pattern of banding on gel electrophoresis. The known Shantz process can be used to obtain crystalline botulinum toxin type A, as set forth in Shantz, E. J., et al, Properties and use of Botulinum toxin and Other Microbial Neurotoxins in Medicine, Microbiol Rev. 56; 80-99:1992. Generally, the botulinum toxin type A complex can be isolated and purified from an anaerobic fermentation by cultivating Clostridium botulinum type A in a suitable medium. The known process can also be used, upon separation out of the non-toxin proteins, to obtain pure botulinum toxins, such as for example: purified botulinum toxin type A with an approximately 150 kD molecular weight with a specific potency of 1-2×108 LD50 U/mg or greater; purified botulinum toxin type B with an approximately 156 kD molecular weight with a specific potency of 1-2×108 LD50 U/mg or greater, and; purified botulinum toxin type F with an approximately 155 kD molecular weight with a specific potency of 1-2×107 LD50 U/mg or greater.
Botulinum toxins and/or botulinum toxin complexes can be obtained from List Biological Laboratories, Inc., Campbell, Calif.; the Centre for Applied Microbiology and Research, Porton Down, U.K.; Wako (Osaka, Japan), Metabiologics (Madison, Wis.) as well as from Sigma Chemicals of St Louis, Mo. Pure botulinum toxin can also be used to prepare a pharmaceutical composition.
As with enzymes generally, the biological activities of the botulinum toxins (which are intracellular peptidases) is dependant, at least in part, upon their three dimensional conformation. Thus, botulinum toxin type A is detoxified by heat, various chemicals surface stretching and surface drying. Additionally, it is known that dilution of the toxin complex obtained by the known culturing, fermentation and purification to the much, much lower toxin concentrations used for pharmaceutical composition formulation results in rapid detoxification of the toxin unless a suitable stabilizing agent is present. Dilution of the toxin from milligram quantities to a solution containing nanograms per milliliter presents significant difficulties because of the rapid loss of specific toxicity upon such great dilution. Since the toxin may be used months or years after the toxin containing pharmaceutical composition is formulated, the toxin can stabilized with a stabilizing agent such as albumin and gelatin.
A commercially available botulinum toxin containing pharmaceutical composition is sold under the trademark BOTOX® (available from Allergan, Inc., of Irvine, Calif.). BOTOX® consists of a purified botulinum toxin type A complex, albumin and sodium chloride packaged in sterile, vacuum-dried form. The botulinum toxin type A is made from a culture of the Hall strain of Clostridium botulinum grown in a medium containing N-Z amine and yeast extract. The botulinum toxin type A complex is purified from the culture solution by a series of acid precipitations to a crystalline complex consisting of the active high molecular weight toxin protein and an associated hemagglutinin protein. The crystalline complex is re-dissolved in a solution containing saline and albumin and sterile filtered (0.2 microns) prior to vacuum-drying. The vacuum-dried product is stored in a freezer at or below −5° C. BOTOX® can be reconstituted with sterile, non-preserved saline prior to intramuscular injection. Each vial of BOTOX® contains about 100 units (U) of Clostridium botulinum toxin type A purified neurotoxin complex, 0.5 milligrams of human serum albumin and 0.9 milligrams of sodium chloride in a sterile, vacuum-dried form without a preservative.
To reconstitute vacuum-dried BOTOX®, sterile normal saline without a preservative; (0.9% Sodium Chloride Injection) is used by drawing up the proper amount of diluent in the appropriate size syringe. Since BOTOX® may be denatured by bubbling or similar violent agitation, the diluent is gently injected into the vial. For sterility reasons BOTOX® is preferably administered within four hours after the vial is removed from the freezer and reconstituted. During these four hours, reconstituted BOTOX® can be stored in a refrigerator at about 2° C. to about 8° C. Reconstituted, refrigerated BOTOX® has been reported to retain its potency for at least about two weeks. Neurology, 48:249-53:1997.
It has been reported that botulinum toxin type A has been used in clinical settings as follows:    (1) about 75-125 units of BOTOX® per intramuscular injection (multiple muscles) to treat cervical dystonia;    (2) 5-10 units of BOTOX® per intramuscular injection to treat glabellar lines (brow furrows) (5 units injected intramuscularly into the procerus muscle and 10 units injected intramuscularly into each corrugator supercilii muscle);    (3) about 30-80 units of BOTOX® to treat constipation by intrasphincter injection of the puborectalis muscle;    (4) about 1-5 units per muscle of intramuscularly injected BOTOX® to treat blepharospasm by injecting the lateral pre-tarsal orbicularis oculi muscle of the upper lid and the lateral pre-tarsal orbicularis oculi of the lower lid.    (5) to treat strabismus, extraocular muscles have been injected intramuscularly with between about 1-5 units of BOTOX®, the amount injected varying based upon both the size of the muscle to be injected and the extent of muscle paralysis desired (i.e. amount of diopter correction desired).    (6) to treat upper limb spasticity following stroke by intramuscular injections of BOTOX® into five different upper limb flexor muscles, as follows:    (a) flexor digitorum profundus: 7.5 U to 30 U    (b) flexor digitorum sublimus: 7.5 U to 30 U    (c) flexor carpi ulnaris: 10 U to 40 U    (d) flexor carpi radialis: 15 U to 60 U    (e) biceps brachii: 50 U to 200 U. Each of the five indicated muscles has been injected at the same treatment session, so that the patient receives from 90 U to 360 U of upper limb flexor muscle BOTOX® by intramuscular injection at each treatment session.    (7) to treat migraine, pericranial injected (injected symmetrically into glabellar, frontalis and temporalis muscles) injection of 25 U of BOTOX® has showed significant benefit as a prophylactic treatment of migraine compared to vehicle as measured by decreased measures of migraine frequency, maximal severity, associated vomiting and acute medication use over the three month period following the 25 U injection.
It is known that botulinum toxin type A can have an efficacy for up to 12 months (European J. Neurology 6 (Supp 4): S111-S1150:1999), and in some circumstances for as long as 27 months, when used to treat glands, such as in the treatment of hyperhydrosis. See e.g. Bushara K., Botulinum toxin and rhinorrhea, Otolaryngol Head Neck Surg 1996; 14(3):507, and The Laryngoscope 109:1344-1346:1999. However, the usual duration of an intramuscular injection of Botox® is typically about 3 to 4 months.
The success of botulinum toxin type A to treat a variety of clinical conditions has led to interest in other botulinum toxin serotypes. Two commercially available botulinum type A preparations for use in humans are BOTOX® available from Allergan, Inc., of Irvine, Calif., and Dysport® available from Beaufour Ipsen, Porton Down, England. A Botulinum toxin type B preparation (MyoBloc®) is available from Elan Pharmaceuticals of San Francisco, Calif.
In addition to having pharmacologic actions at the peripheral location, botulinum toxins may also have inhibitory effects in the central nervous system. Work by Weigand et al, Nauny-Schmiedeberg's Arch. Pharmacol. 1976; 292, 161-165, and Habermann, Nauny-Schmiedeberg's Arch. Pharmacol. 1974; 281, 47-56 showed that botulinum toxin is able to ascend to the spinal area by retrograde transport. As such, a botulinum toxin injected at a peripheral location, for example intramuscularly, may be retrograde transported to the spinal cord.
U.S. Pat. No. 5,989,545 discloses that a modified clostridial neurotoxin or fragment thereof, preferably a botulinum toxin, chemically conjugated or recombinantly fused to a particular targeting moiety can be used to treat pain by administration of the agent to the spinal cord.
A botulinum toxin has also been proposed for or has been used to treat otitis media of the ear (U.S. Pat. No. 5,766,605), inner ear disorders (U.S. Pat. Nos. 6,265,379; 6,358,926), tension headache, (U.S. Pat. No. 6,458,365), migraine headache pain (U.S. Pat. No. 5,714,468), post-operative pain and visceral pain (U.S. Pat. No. 6,464,986), hair growth and hair retention (U.S. Pat. No. 6,299,893), psoriasis and dermatitis (U.S. Pat. No. 5,670,484), injured muscles (U.S. Pat. No. 6,423,319) various cancers (U.S. Pat. Nos. 6,139,845), smooth muscle disorders (U.S. Pat. No. 5,437,291), and neurogenic inflammation (U.S. Pat. No. 6,063,768). Controlled release toxin implants are known (see e.g. U.S. Pat. Nos. 6,306,423 and 6,312,708) as is transdermal botulinum toxin administration (U.S. patent application Ser. No. 10/194,805).
Additionally, a botulinum toxin may have an effect to reduce induced inflammatory pain in a rat formalin model. Aoki K., et al, Mechanisms of the antinociceptive effect of subcutaneous Botox: Inhibition of peripheral and central nociceptive processing, Cephalalgia 2003 September; 23(7):649. Furthermore, it has been reported that botulinum toxin nerve blockage can cause a reduction of epidermal thickness. Li Y, et al., Sensory and motor denervation influences epidermal thickness in rat foot glabrous skin, Exp Neurol 1997; 147:452-462 (see page 459). Finally, it is known to administer a botulinum toxin to the foot to treat excessive foot sweating (Katsambas A., et al., Cutaneous diseases of the foot: Unapproved treatments, Clin Dermatol 2002 November-December; 20(6):689-699; Sevim, S., et al., Botulinum toxin-A therapy for palmar and plantar hyperhidrosis, Acta Neurol Belg 2002 December; 102(4):167-70), spastic toes (Suputtitada, A., Local botulinum toxin type A injections in the treatment of spastic toes, Am J Phys Med Rehabil 2002 October; 81 (10):770-5), idiopathic toe walking (Tacks, L., et al., Idiopathic toe walking: Treatment with botulinum toxin A injection, Dev Med Child Neurol 2002; 44(Suppl 91):6), and foot dystonia (Rogers J., et al., Injections of botulinum toxin A in foot dystonia, Neurology 1993 April; 43(4 Suppl 2)).
Tetanus toxin, as wells as derivatives (i.e. with a non-native targeting moiety), fragments, hybrids and chimeras thereof can also have therapeutic utility. The tetanus toxin bears many similarities to the botulinum toxins. Thus, both the tetanus toxin and the botulinum toxins are polypeptides made by closely related species of Clostridium (Clostridium tetani and Clostridium botulinum, respectively). Additionally, both the tetanus toxin and the botulinum toxins are dichain proteins composed of a light chain (molecular weight about 50 kD) covalently bound by a single disulfide bond to a heavy chain (molecular weight about 100 kD). Hence, the molecular weight of tetanus toxin and of each of the seven botulinum toxins (non-complexed) is about 150 kD. Furthermore, for both the tetanus toxin and the botulinum toxins, the light chain bears the domain which exhibits intracellular biological (protease) activity, while the heavy chain comprises the receptor binding (immunogenic) and cell membrane translocational domains.
Further, both the tetanus toxin and the botulinum toxins exhibit a high, specific affinity for gangliocide receptors on the surface of presynaptic cholinergic neurons. Receptor mediated endocytosis of tetanus toxin by peripheral cholinergic neurons results in retrograde axonal transport, blocking of the release of inhibitory neurotransmitters from central synapses and a spastic paralysis. Contrarily, receptor mediated endocytosis of botulinum toxin by peripheral cholinergic neurons results in little if any retrograde transport, inhibition of acetylcholine exocytosis from the intoxicated peripheral motor neurons and a flaccid paralysis.
Finally, the tetanus toxin and the botulinum toxins resemble each other in both biosynthesis and molecular architecture. Thus, there is an overall 34% identity between the protein sequences of tetanus toxin and botulinum toxin type A, and a sequence identity as high as 62% for some functional domains. Binz T. et al., The Complete Sequence of Botulinum Neurotoxin Type A and Comparison with Other Clostridial Neurotoxins, J Biological Chemistry 265(16); 9153-9158:1990.
Acetylcholine
Typically only a single type of small molecule neurotransmitter is released by each type of neuron in the mammalian nervous system, although there is evidence which suggests that several neuromodulators can be released by the same neuron. The neurotransmitter acetylcholine is secreted by neurons in many areas of the brain, but specifically by the large pyramidal cells of the motor cortex, by several different neurons in the basal ganglia, by the motor neurons that innervate the skeletal muscles, by the preganglionic neurons of the autonomic nervous system (both sympathetic and parasympathetic), by the bag 1 fibers of the muscle spindle fiber, by the postganglionic neurons of the parasympathetic nervous system, and by some of the postganglionic neurons of the sympathetic nervous system. Essentially, only the postganglionic sympathetic nerve fibers to the sweat glands, the piloerector muscles and a few blood vessels are cholinergic as most of the postganglionic neurons of the sympathetic nervous system secret the neurotransmitter norepinephine. In most instances acetylcholine has an excitatory effect. However, acetylcholine is known to have inhibitory effects at some of the peripheral parasympathetic nerve endings, such as inhibition of heart rate by the vagal nerve.
The efferent signals of the autonomic nervous system are transmitted to the body through either the sympathetic nervous system or the parasympathetic nervous system. The preganglionic neurons of the sympathetic nervous system extend from preganglionic sympathetic neuron cell bodies located in the intermediolateral horn of the spinal cord. The preganglionic sympathetic nerve fibers, extending from the cell body, synapse with postganglionic neurons located in either a paravertebral sympathetic ganglion or in a prevertebral ganglion. Since, the preganglionic neurons of both the sympathetic and parasympathetic nervous system are cholinergic, application of acetylcholine to the ganglia will excite both sympathetic and parasympathetic postganglionic neurons.
Acetylcholine activates two types of receptors, muscarinic and nicotinic receptors. The muscarinic receptors are found in all effector cells stimulated by the postganglionic, neurons of the parasympathetic nervous system as well as in those stimulated by the postganglionic cholinergic neurons of the sympathetic nervous system. The nicotinic receptors are found in the adrenal medulla, as well as within the autonomic ganglia, that is on the cell surface of the postganglionic neuron at the synapse between the preganglionic and postganglionic neurons of both the sympathetic and parasympathetic systems. Nicotinic receptors are also found in many nonautonomic nerve endings, for example in the membranes of skeletal muscle fibers at the neuromuscular junction.
Acetylcholine is released from cholinergic neurons when small, clear, intracellular vesicles fuse with the presynaptic neuronal cell membrane. A wide variety of non-neuronal secretory cells, such as, adrenal medulla (as well as the PC12 cell line) and pancreatic islet cells release catecholamines and parathyroid hormone, respectively, from large dense-core vesicles. The PC12 cell line is a clone of rat pheochromocytoma cells extensively used as a tissue culture model for studies of sympathoadrenal development. Botulinum toxin inhibits the release of both types of compounds from both types of cells in vitro, permeabilized (as by electroporation) or by direct injection of the toxin into the denervated cell. Botulinum toxin is also known to block release of the neurotransmitter glutamate from cortical synaptosomes cell cultures.
A neuromuscular junction is formed in skeletal muscle by the proximity of axons to muscle cells. A signal transmitted through the nervous system results in an action potential at the terminal axon, with activation of ion channels and resulting release of the neurotransmitter acetylcholine from intraneuronal synaptic vesicles, for example at the motor endplate of the neuromuscular junction. The acetylcholine crosses the extracellular space to bind with acetylcholine receptor proteins on the surface of the muscle end plate. Once sufficient binding has occurred, an action potential of the muscle cell causes specific membrane ion channel changes, resulting in muscle cell contraction. The acetylcholine is then released from the muscle cells and metabolized by cholinesterases in the extracellular space. The metabolites are recycled back into the terminal axon for reprocessing into further acetylcholine.
What is needed therefore is a therapeutically effective method for treating a skin disorder.

Botulinum toxin therapy for skin disorders


To remarkably decrease the amount of material for the manufacture of ink containers and the volume of the ink containers after use, so as to contribute to the economy of natural resource consumption and solving the problem of destruction of global environment by the waste of products, without sacrificing the easiness of handling of the ink containers for printers, the ink container for directly storing ink is principally constructed by a thin walled vessel contractible according to discharge of ink therefrom, with a nozzle being connected to an end portion of the vessel, with a disk handle being mounted to the nozzle, so that the disk handle can be grasped by five fingers of a hand for carrying the ink container by hand and for removing a cap therefrom. For the ink container being housed in a printer, the ink container is charged into a reinforcing case with the nozzle and the disk handle engaged with an end wall portion of the case, so that the ink container is handled like the case.

1. Field of the Invention
The present invention relates to the art of printer, and more particularly, to an ink container to serve as an ink supply source of a printer and an ink supply source device incorporating such an ink container.
2. Description of the Prior Art
In a printer for automatically continuously printing a large number of prints such as a rotary type stencil printer, the ink consumed according to the progress of printing is continuously supplied from an ink container charged in the printer. As an ink container for this purpose there is known an ink container having a circular cylinder portion of a circular cross section, an end plate member mounted into the cylinder from one end thereof so as to be able to slide along the central axis of the cylinder like a free piston, and an annular end wall closing the other end of the cylinder except a central opening, and a nozzle connected to the central opening, the inside of the cylinder being initially filled with ink with the end plate positioned at the one end, wherein the end plate moves axially in the cylinder toward the other end as the ink in the cylinder is drawn out through the nozzle. (Japanese Patent Laid-open Publication 59-37162) When a printer is operated with an ink container of this construction, the resistance against the drawing out of the ink from the ink container remains always constant regardless of the amount of ink remaining in the container, whereby a large number of prints are available at a continuously stabilized density.
In the ink container of the above-mentioned construction, since the cylinder portion must operate not only as a wall means of a container for storing ink but also as a cylinder member for smoothly guiding the end plate member along the inside wall thereof like a free piston, the cylinder portion forming a principal portion of the ink container must have such a wall thickness that provides a high rigidity enough to operate as a cylinder for guiding a free piston therein, and therefore, a substantial amount of a material such as a synthetic resin or the like is required for the manufacture of the ink container, and further, the used ink container presents substantially the same outer configuration as that in its initial stage, although the end plate member is shifted to the deepest position of the cylinder to be close to the nozzle. Therefore, when the number of used ink containers increases according to the working hour of the printer, a difficulty should arise about the disposal of the used ink containers.
It is well known from old days to construct a fluid storing container to have a bellows construction. Particularly in Japanese Utility Model Application 60-94275 (Laid-open Publication 62-3438), there is proposed a container having a cylindrical portion of a bellows construction having a closed one end and another end having an opening, and a nozzle connected to the opening. Further, it is shown in Japanese Patent Laid-open Publication 6-199349 to construct a bellows type ink container for a printer such that an inner cylinder of a bellows construction projects from an end of a main cylinder portion toward the inside thereof, such that the amount of ink which remains in the ink container after the end of possible discharge of ink therefrom is decreased.
Further, in Japanese Patent Application 9-39712, there is proposed an ink container comprising a vessel constructed from a bag made of a flexible sheet and collapsible to be flat, a nozzle connected to one end of the vessel, and a cylinder member made of a relatively hard sheet material collapsible to be flat, the cylinder member covering a half or nearly the whole length of the bag, wherein the container is inflated to a cylindrical configuration by ink being charged therein.
However, when such a container having a bellows construction or made of a flexible sheet is constructed to have a very thin wall thickness, the cylindrical container formed by the inflation thereof by a charge of ink therein is difficult for seizure by fingers as it readily flattens by the application of pressing forces by the fingers, so as to release the pressing forces, thereby nullifying the seizing function by the fingers. When the container has a simple cylindrical configuration with no bellows, an effective seizure by fingers is more difficult than in a container having bellows. When it is only needed that the container is hung up, a cap mounted to the nozzle may be grasped by tips of fingers. However, when the container filled with ink is charged into a printer, the cap must be removed. In order to remove the cap tightly clamped not to cause a leakage of ink, the cylindrical portion of the container must be firmly held. If a firm holding is not available, it will be very difficult to remove the cap. Further, if the cap is removed by clamping the flexible cylinder portion, at a moment when the cap was removed, the ink will be inadvertently ejected out from the container.

Collapsible ink container having disk shaped handle and ink supply source device encasing the container for printers


In a first exemplary embodiment of the present invention, an automated, computerized method for manipulating an image is provided. The method of the present invention comprises the steps of selecting matched shadow/lit pairs of image portions from each of separate, different materials depicted in the image, utilizing the selected matched pairs to determine spectral ratio information for the image, calculating a correction term as a function of the spectral ratio information and utilizing the correction term to manipulate the image, to remove effects, such as, for example, path radiance.

Images of earth-based objects are routinely captured by satellites in orbit around earth. These images are used in significant and often critical scientific, military and intelligence operations and studies. Typically, the orbiting satellites transmit captured images to earth-based stations for review and study. However, images of earth-based objects, received from a satellite transmission, are often distorted due to effects of the atmosphere. Light reflected from an earth-based object must travel through a thick layer of relatively dense atmosphere before being received by a sensor on board an orbiting satellite. The air in the atmosphere, as well as substances suspended in the atmosphere, such as water droplets and dust, can scatter light that is captured by a sensor on board the satellite. For example, light from the sun can illuminate a microscopic dust particle, that then reflects back to the satellite based sensor. The light measured at each sensor location, (and thus, each pixel of the image) includes the light reflected from the surface of the earth, and all of the light scattered towards the sensor from particles in the path between the earth surface and the orbiting satellite.
Additive intensity at a sensor, caused by light scattered back from particles in the atmosphere, is referred to as path radiance. Path radiance can occur whenever an imaged object is a significant distance from the sensor, and the medium between the object and the sensor is not a vacuum. The removal of path radiance effects is an important objective of designers of systems that involve capturing images from a large distance, such as the design of satellite transmission systems.
In addition to path radiance, similar effects can occur when an image is recorded through transparent glass, cellophane, or other transparent or semi-transparent materials. Other phenomena, such as, for example, ambient specular reflection, while functionally different from path radiance, have a similar effect of increasing measured intensity in different color bands beyond what would be expected in a simple color model such as lambertion reflection.

Method and system for improved detection of material reflectances in an image


The present invention uses multiple global cooling chambers for providing liquid cooling to a plurality of electronic components. The global cooling chambers utilize a non-electrically conductive fluid which is in direct contact with the components to be cooled. The system provides very effective heat transfer rates, environmental isolation of the electronics components and can be deployed in a wide range of applications. Multiple global cooling chambers allows for the hot swapping of cards during operation of the system. Valves provide the ability to minimize the amount of interaction between the cooling fluid and air outside the chambers.

Liquid cooling is becoming widely understood in the field of electronics cooling. Rather than use air to cool heat producing components, liquid is used to absorb and transport the heat. Liquids are typically much more efficient than air as a heat transfer fluid since they have considerably higher thermal conductivities, specific heat capacities and provide the opportunity for phase change processes.
Liquid cooling systems used to cool commercial type electronics generally utilize a closed loop process. Although some liquid cooling systems, such as heat pipes, are passive, active systems provide system flexibility needed for most cooling applications. With active systems, the fluid is pressurized via one or more pumps. The pressurized fluid is delivered to the cooling module wherein the fluid absorbs heat from an electronic component. The fluid leaving the cooling module is transported to a heat exchanger wherein the heat is removed from the fluid. Many other components, such as filters, may be placed into the closed loop system for additional system functionality.
There are many ways for the liquid of a cooling system to absorb heat from the heat producing device. Forced convection is often used by cold plates. Cold plates replace heat sinks and keep the fluid separate from the electronics to be cooled. Inside the cold plate can be features such as micro-channels and mini-channels, which increase the surface area and overall heat transfer. Cold plates are required for use with conductive liquid cooling fluids, such as water. Water must be kept separate from the electronics since it would obviously short out the circuits and cause irreparable harm to the electronic systems and components.
Dielectric fluids are electrically inert to electronic components. Depending upon the exact type of fluid, dielectric fluids typically have breakdown voltages in excess of air. Fluorinert (a trademark of 3M) is a commercially available dielectric fluid that has been used in liquid cooling systems for several decades. Most electronic components can be placed directly in contact with dielectric fluids, such as Fluorinert. By placing the fluid in direct contact with components to be cooled, heat transfer rates can be much greater than typical cold plate systems. In addition, entire boards having many electronic components of varying height and shapes can be cooled by a single liquid cooling system. In addition to Fluorinert, other dielectric fluids are available such as commonly used refrigerants.
A significant challenge in using dielectric fluids within closed loop cooling systems is that they typically have poor heat transfer properties. Fluorinert, for example, has a thermal conductivity value in the range of air. Water has a thermal conductivity several orders of magnitude greater. The result is that it can be difficult to get heat into dielectric fluids. To make dielectric fluids effective, two-phase cooling can be employed. Rather than use single phase heat transfer wherein a fluid is heated up by sensible heat gains, two-phase cooling takes advantage of changing liquid into vapor. Liquid absorbs heat and transforms into vapor which requires substantial amounts of energy. The vapor is condensed by a heat exchanger back to liquid form. The result is a highly efficient system. Preferably, thin-film evaporative cooling is used to maximize heat transfer coefficients.
Spray cooling is an ideal thin-film cooling method for producing effective and efficient dielectric liquid cooling systems. Fluid is pumped via a pump and delivered to a spray module. Nozzles, preferably atomizers, break up the liquid into small drops that travel to the cooling surface with significant momentum. The drops create a very thin coolant film which readily changes phase to a vapor state. The drops also entrain vapor within the module. Entrained vapor can be used to further reduce the thickness of the cooling film and reduce localized pressures, both results increase heat transfer coefficients. Spray cooling can be used within cold plates for systems that have localized heat sources, and can also be used within global type systems that spray the fluid directly on entire electronic systems. A coldplate spray cooling system is described by U.S. Pat. No. 7,104,078 and U.S. Pat. No. 5,220,804; and a global spray cooling system is described by U.S. Pat. No. 5,880,931 and U.S. Pat. No. 6,976,528.
Global spray cooling allows electronics to be used in revolutionary ways. By creating a completely sealed chamber for the electronics, the systems can be used in environments that may be nearly void of air, under water, and in extreme hot and cold. Global cooling is also ideal for benign environments, such as data centers. Global cooling can be used for blade servers which provides the ability to create very power dense systems and racks.
One problem with prior art global cooling systems is that because the electronics reside within a single chamber, the entire computing system must be shut down in order to provide service and maintenance of a single board within. Although the maintenance and service requirements may be perfectly acceptable for global cooling systems used in airplanes and standalone systems, the requirements are not optimal for use with systems that must be used in 7×24 applications. Computers used in data centers for example, are expected to be plug and play.
One method of creating hot-swappable electronics within a global cooling system is the "clamshell" method, such as described by U.S. Pat. No. 6,955,062. Cards are completely enclosed by a chamber. Each chamber has an inlet and an outlet comprised of quick disconnect couplings or blind mate connectors. The quick disconnect couplings are part of an electrical backplane. Each chamber can be removed from the backplane assembly individually. A weakness in the clamshell design is that the backplane assembly is not environmentally isolated. The result is that the system can not be placed in very harsh working environments. In addition, the cards typically have to be custom designed in order to interface with the clamshell housing.
Another problem with prior art global cooling systems that utilize single and large chambers for cooling, is that a significant amount of the fluid within is open to the environment during service and maintenance. Perfluorocarbon type fluids are very stable molecules, and hence, there is very little risk in the fluid breaking down. Perfluorocarbon type fluids do have the ability to absorb significant amounts of air. During maintenance cycles, it is disadvantageous to have the cooling fluid absorb air, or non-condensable gases, as during operation the non-condensable gases cause increased system pressures, saturation temperatures and temperatures of electronics. Other fluids, such as the Novec family (a trademark of 3M), may break down into other substances with the introduction of water, or water vapor. Prior art single chamber global cooling systems do provide the means to reduce the exposure of the fluid within the system to fluid and gases as part of the environment.
In these respects, the multi-chamber cooling system according to the present invention substantially departs from conventional concepts of the prior art, and in doing so provides an apparatus primarily designed to provide global cooling to electronics while allowing cards to be hot-swapped.

Method of reducing fluid emissions from a global spray cooling system


The present invention relates to a pet bed that includes a heating layer which is formed of an enclosure and a heating composition sealed inside the enclosure. The enclosure includes a gas-permeable section such that the heating composition generates heat when a gas is received through the gas-permeable section. The pet bed further includes (i) a liner attached to the heating layer to engage a pet as the pet lies on the pet bed; (ii) a conforming layer attached to the heating layer such that the conforming layer conforms to the shape of the pet as the pet lies on the pet bed; and/or (iii) a backing layer attached to the heating layer such that the backing layer restricts movement of the pet bed. The enclosure may further include a cover over the gas-permeable section such that the heating composition generates heat when the cover is removed from the enclosure.

Many pets suffer from a variety of maladies, such as stiffness, muscle pain, arthritis, lumbago, rheumatism and neuralgia (among others). One way to treat a pet that has these types of maladies is to provide heat to the pet. Some known heat-treating methods include direct application of heat to the body using items such as a towel, jelly and/or paste.
One concern with such heat-treating methods relates to the ability to control the amount of heat that is applied to the pet, especially since pets are incapable of providing verbal feedback as to the amount of heat that they are receiving. A burn could result if too much heat is applied to a pet, and a pet may receive relatively ineffective therapy if too little heat is applied. Another concern with these types of heat-treating methods relates to their ability to apply heat for extended periods of time.
Pet owners commonly have their pets sleep in an environment where no heating facilities are available. As an example, pets often sleep in unheated garage spaces that are near their owner's home. A pet bed is typically used to keep pets warm as they sleep and/or to provide heat therapy to an ailing pet.
Some conventional pet beds include a thermoelectric device that generates heat within the pet bed. One of the drawbacks with such pet beds is that the thermoelectric devices require electricity to generate heat. Since electricity is not available in many locations, bulky, expensive and environmentally unfriendly batteries are often required to supply the necessary electricity.
Accordingly, there is a need for a pet bed that applies heat to a pet without using electricity. The pet bed should also be capable of maintaining a safe temperature for an extended period of time.


The invention provides methods of identifying herbicidal auxins. The invention further provides auxin-herbicide-resistant plants and genes conferring auxin-herbicide resistance. This invention also provides a method of identifying other proteins that bind picolinate auxins from additional plant species. The invention further provides a method to identify the molecular binding site for picolinate auxins. The invention also includes the use of the picolinate herbicidal auxin target site proteins, and methods of discovering new compounds with herbicidal or plant growth regulatory activity. The invention also includes methods for producing plants that are resistant to picolinate herbicidal auxins. Specific examples of novel proteins associated with herbicide binding include AFB5, AFB4, and SGT1b.

The use of herbicides for weed control is an extremely valuable agricultural practice to protect the yield of crop plants and to manage the growth of vegetation in pastures and other sites. However the use of many herbicides is becoming problematic through the advent of field resistance and also from increased toxicological and environmental concerns associated with certain pesticidal chemistries and modes of action. Thus there is a continuing need for new herbicidal chemistries.
There are currently a limited number of herbicidal classes that have proven to exhibit the desired attributes for a beneficial modern herbicide such as low incidence of resistance development and low potential for toxicological side effects. One such class is the auxinic herbicides that include such compounds as 2,4-D and picloram. This class can be further subdivided into compounds that contain a picolinate moiety (e.g., picloram, aminopyralid, clopyralid), those that contain an aryloxyacetate moiety (e.g., 2,4-D, fluroxypyr, triclopyr etc.) and others (e.g., dicamba). All of these compounds elicit plant symptoms similar to excessive treatment with the natural plant hormone indole acetic acid (IAA) and induce similar physiological events, eventually leading to plant death. Interestingly, the widespread use of auxinic herbicides for many years has not resulted in significant field resistance. In addition, the auxinic mode of action is specific to plants and many of the auxinic herbicides exhibit favorable environmental profiles. Thus methods for the discovery of new compounds that act via the auxinic mode of action would be of great benefit, particularly those with increased potency, wider spectrum, optimal soil persistency or low cost of manufacture.
Genes that confer resistance to certain herbicides have found utility in the development of herbicide-tolerant crops by transgenic or mutagenic selection methods. Many auxinic herbicides have broad spectrum herbicidal activity but their use is limited by the fact that the desired crop or pasture component species is sensitive to the herbicide. This is particularly the case for the picolinate class of auxinic herbicides. Thus there is an unfulfilled need for herbicide-tolerance mechanisms that would be applicable to the picolinate class of auxinic herbicides.


The present invention is a probe, a primer, and an antibody, for detecting a dopaminergic neuron proliferative progenitor cell. According to the present invention, there is provided a polynucleotide probe and a polynucleotide primer for use in the detection or selection of a dopaminergic neuron proliferative progenitor cell, which can hybridize with a polynucleotide consisting of a nucleotide sequence of a Nato3 gene, or a complementary sequence thereto, and an antibody against a Nato3 protein, or a part thereof for use in the detection or selection of a dopaminergic neuron proliferative progenitor cell.

The dopamine system is a very important system involved in movement control, hormone secretion control, affectivity control, and so forth, which are important in the mammalian brain. Therefore, abnormalities in dopaminergic neurotransmission cause various disorders of the neural system. For example, the Parkinson's disease is a neurodegenerative disease of the extrapyramidal system which is caused by specific degeneration of dopaminergic neurons in the midbrain substantia nigra (HARRISON'S PRINCIPLES OF INTERNAL MEDICINE Vol. 2 23rd ed., Isselbacher et al. edited by McGraw-Hill Inc., NY (1994) pp. 2275-7).
As a method for treating the Parkinson's disease, a method of orally administering L-DOPA (3,4-dihydroxy-phenylalanine) has been mainly adopted for compensating the decrease in the amount of the produced dopamine, but it is known that the duration of the effect is not good.
Accordingly, as a method for compensating the loss of dopaminergic neurons, recently, there has been attempted a therapeutic method of transplanting a midbrain ventral region of a 6-9 week aborted fetus containing dopaminergic neuron precursors (U.S. Pat. No. 5,690,927; Spencer et al. (1992) N. Engl. J. Med. 327:1541-8; Freed et al. (1992) N. Engl. J. Med. 327:1549-55; Widner et al. (1992) N. Engl. J. Med. 327:1556-63; Kordower et al. (1995) N. Engl. J. Med. 332:1118-24; Defer et al. (1996) Brain 119:41-50; and Lopez-Lozano et al. (1997) Transp. Proc. 29:977-80). However, at the present time, in addition to cell supply and ethical issues (Rosenstain (1995) Exp. Neurol. 33:106; Turner et al. (1993) Neurosurg. 33:1031-7), various other problems have been indicated, for example, risk of infectious contamination, immunologic transplant rejection (Lopez-Lozano et al. (1997) Transp. Proc. 29:977-80 and Widner and Brudin (1988) Brain Res. Rev. 13:287-324), low survival rate due to the fetus tissue's mainly dependence on lipid metabolism rather than glycolysis (Rosenstein (1995) Exp. Neurol. 33:106), and so forth.
As a method for solving the problem of the ethical issues or supply shortage, for example, a method by using a cortex, a striation, and midbrain cells, derived from a pig, and so forth have been proposed (for example, Japanese Patent Laid-Open Publication No. 10-508487, No. 10-508488, and No. 10-509034). However, in this method, a complex procedure for modifying an antigen on the cell surface (MHC class I antigen) is required to suppress rejection. As a method for solving the transplant rejection, for example, a method involving local immunosuppression by simultaneously transplanting Sertoli cells has been proposed (Japanese Patent Laid-Open Publication No. 11-509170 and No. 11-501818; and Selawly and Cameron (1993) Cell Transplant 2:123-9). It is possible that transplant cells are obtained from a relative whose MHC matches, bone marrow of another person, a bone marrow bank, a cord blood bank, and so forth. However, if patient's own cells can be used, the problems of rejection can be solved without extra procedures and trouble.
Accordingly, it has been expected that, instead of cells derived from an aborted fetus, a differentiation system of dopaminergic neurons in vitro from non-neural cells such as embryo-stem (ES) cell and bone marrow stromal cells are utilized as a transplant material. Actually, there is a report that a functional dopaminergic neuron is formed by ES cell transplantation into lesion striation of a rat Parkinson's disease model (Kim et al. (2002) Nature 418:50-56). It is thought that in the future, importance of regenerative medicine from ES cells or the patient's own neural stem cells will increase.
On the other hand, in the treatment of damage of neural tissue, restructuring of brain function is required, and for forming appropriate linkage with surrounding cells (network formation), not mature cells but progenitor cells that can differentiate into neurons in vivo are required to be transplanted. However, in the transplantation of neuron progenitor cells, in addition to the above-described problem regarding supply, there is a problem that the progenitor cells can differentiate into a nonuniform cell population. For example, in the treatment of the Parkinson's disease, it is necessary that dopaminergic neurons are selectively transplanted among catecholamine-containing neurons. Before now, as transplant cells for use in the treatment of the Parkinson's disease, there has been proposed a striate body (Lindvall et al. (1989) Arch. Neurol. 46:615-31 and Widner et al. (1992) N. Engl. J. Med. 327:1556-63), an immortalized cell line derived from human embryonic nerve (Japanese Patent Laid-Open Publication No. 8-509215, No. 11-506930, and No. 2002-522070), a post-mitotic human neuron of NT2Z cells (Japanese Patent Laid-Open Publication No. 9-5050554), a neuron primordial cell (Japanese Patent Laid-Open Publication No. 11-509729), a cell transfected with an exogenous gene so as to produce catecholamine such as dopamine, a bone marrow stromal cell (Japanese Patent Laid-Open Publication No. 2002-504503 and No. 2002-513545), an ES cell in which a gene is modified (Kim et al. (2002) Nature 418:50-56), and so forth. However, none of these contain only dopaminergic neurons or cells to differentiate into dopaminergic neurons.
As a method for selectively condensing or isolating dopaminergic neurons from undifferentiated cell population, there has been proposed a method of, introducing a reporter gene expressing a fluorescent protein under control of promoter/enhancer of a gene such as tyrosine hydroxylase (TH) expressed in dopaminergic neurons into each cell of the cell population, isolating the cells emitting fluorescence, and thereby visualizing the alive dopaminergic neurons to condense, segregate or identify (Japanese Patent Laid-Open Publication No. 2002-51775). However, this method requires a complex step of introduction of an exogenous gene, and furthermore, when used in gene treatment, the existence of the reporter gene causes problem of toxicity and immunogenicity.
As described above, now, one of the largest problems in transplantation treatment for the Parkinson's disease is that the either dopaminergic neuron progenitor cells derived from the midbrain ventral region of aborted fetus or induced to differentiate are a mixture of various cells. It is desirable that only a desired cell species is isolated and used, considering safety in neural network formation. Furthermore, considering survival or ability for correctly forming a network in a brain in which the cells are transplanted, it can be said that it is desirable from the treatment effect that earlier proliferative progenitor cells are isolated and transplanted.
Before now, as a gene that selectively expresses in the dopaminergic neuron proliferative progenitor cells, Lrp4 (WO 2004/065599) has been reported. Additionally, some markers of dopaminergic neuron progenitor cells have been reported (WO 2004/038018 and WO 2004/052190). Among them, with respect to Lmx1a, expression has been confirmed in human and mouse dopaminergic neuron proliferative progenitor cells, postmitotic dopaminergic neuron precursor cells, and dopaminergic neurons (WO 2005/052190).
By the way, the Nato3 gene is a transcription factor having a basic helix-loop-helix (bHLH), and it has been reported that the Nato3 gene is expressed in the midbrain, and has an important role in the developmental process (Segev, E., N. Halachmi, A. Salzberg, and N. Ben-Arie. 2001. Mech Dev 106:197-202). Moreover, it has been reported that Nato3 is expressed in the midbrain, particularly, the most ventral side (floor plate), and relates to differentiation of neural cells (Verzi, M. P., J. P. Anderson, E. Dodou, K. K. Kelly, S. B. Greene, B. J. North, R. M. Cripps, and B. L. Black. 2002. Dev Biol 249:174-90).
However, it is not reported that Nato3 is selectively expressed in dopaminergic neuron proliferative progenitor cells.

Dopaminergic neuron proliferative progenitor cell marker Nato3


The invention relates to a method and device for depositing at least one layer, particularly a semiconductor layer, onto at least one substrate, which is situated inside a process chamber of a reactor while being supported by a substrate holder. The layer is comprised of at least two material components provided in a fixed stoichiometric ratio, which are each introduced into the reactor in the form of a first and a second reaction gas, and a portion of the decomposition products form the layer, whereby the supply of the first reaction gas, which has a low thermal activation energy, determines the growth rate of the layer, and the second reaction gas, which has a high thermal activation energy, is supplied in excess and is preconditioned, in particular, by an independent supply of energy. The first reaction gas flows in a direction toward the substrate holder through a multitude of openings, which are distributed over a surface of a gas inlet element, said surface being located opposite the substrate holder. According to the invention, the second process gas is preconditioned with a plasma before entering the process chamber, and it enters the process chamber at the edge of the substrate holder directly thereabove and flows parallel to the substrate holder surface.

CVD systems, and in particular MOCVD systems, are used to produce light-emitting diodes, in particular green, blue and also white light-emitting diodes. Compound nitrides are deposited on a semiconductor surface in order to deposit white light-emitting diodes. In the production processes used hitherto, first and second process gases, for example in the form of TMG or NH3, have been passed into the process chamber, where the process gases decompose or react with one another, and the reaction or decomposition products are deposited on the surface of a substrate so as to form a layer or layers. The processes used hitherto are expensive, since the outlay on materials, in particular with regard to the nitrogen hydride, is considerably higher than the outlay on materials for the metal alkyl, for example TMG. NH3, PH3 or ASH3 have to be introduced into the process chamber in a concentration which is higher by an order of magnitude than the metal alkyls. Although the hydrides are relatively inexpensive compared to the alkyls, the consumption costs are approximately the same, on account of the high consumption. The high consumption is a result of the high thermal activation energy of the hydrides compared to the activation energies of the metal alkyls.
To promote decomposition of the reaction gases, U.S. Pat. No. 4,539,068 proposes that a plasma be ignited between the gas inlet member and the substrate holder.
U.S. Pat. No. 3,757,733 also proposes a plasma in the process chamber for this purpose.
U.S. Pat. No. 6,289,842 B1 deals with the deposition of semiconductor layers in the MOCVD system, in which the process gases are introduced into the process chamber through a showerhead.
A plasma pre-treatment of a reaction gas is also known from JP 08-167596.
WO 01/46498 describes introducing the alkyls separately from the hydrides.

Process and apparatus for depositing semiconductor layers using two process gases, one of which is preconditioned


There is provided a semiconductor device including regular cells (16) disposed in a regular sector (10) and connected to a word line (14), and a plurality of reference cells (26) used in reading data from the regular cells (10), wherein one of the reference cells is selected based on a word line distance associated with a regular cell (16) from which data is read. In accordance with the present invention, it is possible to reduce the difference in delay times in the outputs to the sensing amplifier (30) from the regular cell (16) and the reference cell (26), by selecting one of a plurality of reference cells (26) in response to the word line distance of the regular cell from which data is read. It is therefore possible to provide a semiconductor device in which the chip area can be reduced and the sensing operation can be accelerated.

1. Field of the Invention
This invention relates generally to semiconductors, and more particularly, to a semiconductor device having a semiconductor memory.
2. Description of the Related Art
Some semiconductor memory devices compare data in a reference cell and data in a regular cell to read the data from the regular cell. Referring to FIG. 1, a flash memory will be described as an example of such a semiconductor memory device.
FIG. 1 is a block diagram of memory cells and periphery circuitry therefor in accordance with a conventional flash memory. A regular sector 10 includes regular cells 16. Regular cells 16a, 16b, and 16c of the regular cells 16 are respectively connected by word lines 14a, 14b, and 14c and bit lines 18. The word lines 14a, 14b, and 14c are connected to a word driver 12. The bit lines 18 are connected to a sensing amplifier 30. A reference cell 26 is disposed in a reference sector 20. The reference cell 26 is connected by a word line 24 and a connection line 32. The word line 24 is connected to a reference word driver 22 and the connection line 32 is connected to the sensing amplifier 30.
Data reading is described with the regular cell 16a serving as an example. The word driver 12 selects the word line 14a connected to the regular cell 16a. The bit line 18 connected to the regular cell 16a is then selected. The sensing amplifier 30 compares the threshold voltage of the regular cell 16a and that of the reference cell 26. This accomplishes reading of the regular cell 16a to learn whether the regular cell 16a represents "0" or "11".
Each of the regular cells 16 has a "word line distance" which is a distance along each of word lines 14 from the word driver 12 to each of the regular cells 16. Similarly, each of the reference cells 26 has a "reference word line distance" which is a distance along each of the reference word lines from the reference word driver 22 to each of the reference cells 26.
As an example of a semiconductor memory device having multiple reference cells, Japanese Patent Application Publication 9-270195 discloses a semiconductor device that includes multiple reference cells having different resistances and capacitances in their wirings to the sensing amplifier. Japanese Patent Application Publication 10-11985 discloses a semiconductor device having a reference cell arranged close to the regular cell.
In accordance with conventional techniques, the word driver 12 is located on one side of the regular sector 10 in order to reduce a chip area. Such reduced chip area increases the number of the regular cells 16 connected to each of the word lines 14. Accordingly, when the chip area is reduced, the word line 14 becomes longer. This causes several shortcomings. Referring to FIG. 1 again, the regular cells 16a, 16b, and, 16c have different word line distances La, Lb, and, Lc, respectively. As the word line 14 lengthens, differences become greater between the word line distances La, Lb, and, Lc. This increases the differences in the resistances and capacitances of the word lines 14 applied to the regular cells 16. Consequently, this will cause different delay times in outputs to the sensing amplifier 30 from the regular cells 16a, 16b, and 16c.
For example, when there the delay time of the output from the reference cell 26 to the sensing amplifier 30 is configured almost equal to that of the delay time from the regular cell 16b to the sensing amplifier 30, the delay time from the regular cell 16a to the sensing amplifier 30 is shorter than the delay time from the reference cell 26 to the sensing amplifier 30. On the other hand, the delay time from the regular cell 16c to the sensing amplifier 30 is longer than the delay time from the reference cell 26 to the sensing amplifier 30. If the delay time varies depending on the regular cells 16 in this manner, there will be no operation margin in the sensing amplifier 30 and the sensing amplifier 30 will operate unstably. In order to prevent the afore-described shortcomings, a limitation is set on the number of regular cells connected to the word line 14. Alternatively, the operating time of the sensing amplifier 30 must necessarily be lengthened. In other words, it is difficult to realize both reduction of the chip area and speeding up of the sensing operation.

Semiconductor device and programming method therefor


A method and system for providing a magnetic memory device are disclosed. The method and system include providing a magnetic element that includes a data storage layer having at least one easy axis in at least a first direction. The method and system also include providing a hard bias structure surrounding a portion of the magnetic element. The hard bias structure is also configured to provide at least one hard bias field essentially parallel to the at least the first direction or essentially perpendicular to the at least the first direction.

FIGS. 1A and 1B depict conventional magnetic elements 10 and 10′. Such conventional magnetic elements 10/10′ can be used in non-volatile memories, such as MRAM. The conventional magnetic element 10 is a spin valve and includes a conventional antiferromagnetic (AFM) layer 12, a conventional pinned layer 14, a conventional nonmagnetic spacer layer 16 and a conventional free layer 18. Other layers (not shown), such as seed or capping layer may also be used. The conventional magnetic element 10 also typically has an elliptical shape 11, and thus a shape anisotropy that favors a magnetization that is substantially parallel to the long axis, 1, of the ellipse. The conventional pinned layer 14 and the conventional free layer 18 are ferromagnetic. Thus, the conventional free layer 18 is depicted as having a changeable magnetization 19. The conventional nonmagnetic spacer layer 16 is conductive. The AFM layer 12 is used to fix, or pin, the magnetization of the pinned layer 14 in a particular direction. The magnetization of the free layer 18 is free to rotate, typically in response to an external magnetic field. The conventional magnetic element 10′ depicted in FIG. 1B is a spin tunneling junction. Portions of the conventional spin tunneling junction 10′ are analogous to the conventional spin valve 10. However, the conventional barrier layer 16′ is an insulator that is thin enough for electrons to tunnel through in a conventional spin tunneling junction 10′. Note that only a single spin valve 10 is depicted, one of ordinary skill in the art will readily recognize that dual spin valves including two pinned layers and two nonmagnetic layers separating the pinned layers from the free layer can be used. Similarly, although only a single spin tunneling junction 10′ is depicted, one of ordinary skill in the art will readily recognize that dual spin tunneling including two pinned layers and two barrier layers separating the pinned layers from the free layer, can be used. More recently, structures having two pinned layers and two layers, one barrier and one conductive, separating the pinned layers from the free layers have been developed, particularly for use when exploiting spin transfer in programming.
Depending upon the orientations of the magnetization 19/19′ of the conventional free layer 18/18′ and the conventional pinned layer 14/14′, respectively, the resistance of the conventional magnetic element 10/10′, respectively, changes. When the magnetization 19/19′ of the conventional free layer 18/18′ is parallel to the magnetization of the conventional pinned layer 14/14′, the resistance of the conventional magnetic element 10/10′ is low. When the magnetization 19/19′ of the conventional free layer 18/18′ is antiparallel to the magnetization of the conventional pinned layer 14/14′, the resistance of the conventional magnetic element 10/10′ is high.
To sense the resistance of the conventional magnetic element 10/10′, current is driven through the conventional magnetic element 10/10′. Typically in memory applications, current is driven in a CPP (current perpendicular to the plane) configuration, perpendicular to the layers of conventional magnetic element 10/10′ (up or down, in the z-direction as seen in FIG. 1A or 1B). Based upon the change in resistance, typically measured using the magnitude of the voltage drop across the conventional magnetic element 10/10′, the resistance state and, therefore, the data stored in the conventional magnetic element 10/10′ can be determined.
FIG. 2 depicts a conventional MRAM 50 that uses the magnetic element 10 or 10′. The MRAM 50 includes the magnetic element 10/10′, bit line 52 and word line 54. In conventional MRAM, the conventional magnetic element 10/10′ is written using an in-plane magnetic field that is approximately forty-five degrees from the axis in which the magnetization 19/19′ lie. This magnetic field is typically provided by driving current through two write lines, the bit line 52 and the word line 54, which are oriented perpendicular and which cross in the region of the conventional magnetic element 10/10′. Current driven in the bit line 52 generates a magnetic field that is parallel or antiparallel to the magnetization of the free layer 18/18′. Current driven in the word line 54 generates a magnetic field that is perpendicular to the magnetization 19/19′ of the free layer 18/18′. This magnetic field reduces the field required to be generated by current in the bit line 52 to switch the direction of magnetization 19/19′ of the free layer 18/18′. Thus, the sum of the two magnetic fields generated by currents in the lines 52 and 54 allows the magnetization 19/19′ to be switched. Depending upon the direction of the magnetic field, the magnetization 19/19′ of the free layer 18/18′ can be switched to have an equilibrium position parallel or antiparallel to the magnetization of the pinned layer 14/14′.
Although the conventional magnetic elements 10/10′ can be used to store data in an MRAM, one of ordinary skill in the art will readily recognize that there are a number of drawbacks. Of these, the primary issues include poor write selectivity and a high write current required to write to the conventional magnetic elements 10/10′. Typically, a magnetic cell includes the conventional magnetic element 10/10′ and other element(s), such as a selection transistor. Poor write selectivity results in memory cells in addition to the desired memory cell being written. These unintentionally written cells are typically located in the regions that either the bit line or word line has passed current through so that the cells encounter magnetic field that the current generates. During manufacturing, defects may be introduced into elements within the memory cells to form pinning sites of magnetization. Manufacturing also results in variations in the size and shape of the conventional magnetic elements 10/10′, as well as other portions of the memory cell. The pinning sites usually cause local sub-domain formation and drag the magnetization switching. It essentially broadens the switching field distribution. The variations in the memory cell size and shape cause variations in the internal demagnetizing field. The magnetic field produced within the memory cell (internal magnetic field) may vary widely from cell to cell. The variations in the internal magnetic field mean that the magnetic field required to switch the free layer magnetization 19/19′ of a particular magnetic cell (required write field) varies from cell to cell. Variations in the required write field mean that unintentional switching could happen for those cells with lower switching fields (required write fields) even they only encounter a single-direction magnetic field from either bit line or word line current. Consequently, unintentional cell writing may occur. Thus, defects and variations in the memory cell size and shape may result in a large distribution in the required write field and unintentional cell writing. This, in the memory application, makes it hard to find the operation window of the switching currents and causes reliability problems.
Writing to conventional magnetic cells may also require a larger write current, which is undesirable. As the memory application goes for higher capacity and thus higher memory cell density, the cell size needs to be reduced in order to accommodate more cells within limited chip area. On the other hand, while the cell size decreases, the required switching field increases rapidly. A higher applied magnetic field requires a higher current to be driven through the write lines. This higher current is undesirable, for example due to increased power consumption. In addition, for the more advanced technology node, the maximum current that the metal lines could sustain is limited due to the reduced metal line cross-section.
Efforts have been made to address issues, for example in toggle writing. In one scheme, stray fields from unbalanced synthetic layers in a conventional magnetic element 10/10′ are used to reduce the switching field. However, one of ordinary skill in the art will recognize that such schemes have drawbacks. For example, stray fields may not be uniform across a cell or among cells. In particular, stray fields at the edges of a memory cell may be quite large. Consequently, a loss of writing integrity may occur. In addition, the stray fields are typically quite sensitive to the shape, size, and wall profile for a magnetic memory element. As a result, the biasing from stray fields may be difficult to control.
Accordingly, what is needed is a system and method for providing a magnetic memory element that can be switched using a lower current and that has improved switching characteristics. The present invention addresses such a need.

Magnetic devices having a hard bias field and magnetic memory devices using the magnetic devices


A container can be juxtaposed with another container to form an integrated package of containers. Each container is substantially triangular in horizontal section and forms first, second and third walls and has a top enclosed bottom. Each top of the container is formed as a substantially T-top closure formed from first and second pinched walls converging at the third wall. A container can be selectively dimensioned and juxtaposed together so that the containers form a rectangular configured package. The containers can be held together to maintain the juxtaposed containers in a substantially rectangular configuration.

Point-of-purchase displays are becoming increasingly important in the global economy where stiff competition is ever present. Container design also is increasingly important in order to obtain containers that can be stored with minimum shelf requirements, while also allowing ready inspection of various containers and their contents. Also, multi-compartment containers are becoming increasingly important because a consumer may desire to purchase a integrated package of containers, with each container having a particular food material or other content such that the individual containers have different ingredients but are sold as an integrated package.
There is a need, then, for a container that is readily formable from a simple blank design but also can be juxtaposed with other containers in a pattern for point-of-purchase display, has ready visibility, and maintains minimum space requirements. The package also should be readily formed, from a blank, easily filled with any contents, closed and then opened by a consumer without difficulty.
It is also known to form multi-compartment containers such as that disclosed in U.S. Pat. No. 4,139,114 to Long, et al., where separate containers are juxtaposed into one compartmentalized package. The containers can be assembled together to form a package for point-of-purchase display and then multiply filled. The containers could be held together by a solder globule, such as disclosed in the '114 Long patent, by hook and pile fasteners (sold under the tradename Velcro.TM.), such as disclosed in U.S. Pat. No. 5,007,540 to Beasely et al., or by interconnecting integrally formed components of containers such as disclosed in U.S. Pat. No. 5,158,191 to Douglas, et al. The packages formed from the assembled containers can then be grouped together to save space in a crowded display or storage area such as point-of-purchase display shelves in retail outlets.
A major drawback to some prior art integrated packages is the method and structure used to hold the containers together. A solder globule as disclosed in the Long '114 patent may not be aesthetically pleasing. Solder also may not be practical if the containers are formed from a material other than sheet metal, such as paperboard, plastic, or glass. Some of the containers may be aesthetically formed and pleasing to the eye with graceful and smooth sides and lines. Broken solder joints, hook and pile fasteners secured to the container sides, or integrally formed connectors would detract from the appearance of a container when it is separated from the overall package.
Another drawback of some prior art integrated packages is the time consuming process of separately filling each container, then assembling the containers together to form the package. If the containers were grouped together as a package prior to filling, the containers would have to be assembled and then advanced to a container filling station without production loss. In many instances, however, containers are aesthetically designed and noncylindrical, making high speed filling more difficult because a noncylindrical package is often more difficult to control during processing than a cylindrical package.

Container, method of filling and closing, and blank used to form the container


A communications system allocates communication bandwidth to calls in such a manner for optimizing network system performance. The system uses knowledge about the state of the past and present network demand, and network resources. Predictions of future demand and future network resources are used to calculate future network performance. Allocation decisions are chosen based on network performance calculations and probabilities of achieving future network states.

1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to a system and a method for allocating communication system resources to calls for optimizing network system performance.
2. Description of Related Art
In a typical satellite communications system, caller communication units are linked to ground-based communication facilities, or ground nodes, which, in turn, are linked to satellites. In some cases, individual communication units are linked directly to a satellite. The amount of caller traffic in a communications system is limited by the available communication bandwidth of the system. When caller demand exceeds the capacity of the system, new callers are denied access.
In conventional communication systems, there is a fixed amount of satellite bandwidth assigned to each ground node. The available bandwidth in these systems is often used inefficiently. For example, one ground node may be overloaded with calls, denying access to new callers, whereas a neighboring ground node may be underutilized, leaving unused satellite bandwidth assigned to that ground node. When a ground station becomes overloaded with calls, there is no mechanism in a conventional satellite system for transferring satellite bandwidth from an underutilized ground station.
To overcome this deficiency, demand-assigned multiple access (DAMA) systems utilize a central control station that allocates satellite bandwidth on a call-by-call basis. Such conventional systems employ a simple, greedy strategy for assigning satellite bandwidth. That is, a ground node requests additional bandwidth from the central control station when a new call is received. The central control station assigns satellite bandwidth to the ground nodes as bandwidth requests are received allowing bandwidth to be reassigned from an underutilized ground node to an overloaded one.
Instead of using a greedy approach, a few conventional satellite systems use a predictive approach, whereby the central control station predicts which stations will be receiving a high call demand, and allocates extra bandwidth to those stations in anticipation of their future need.
Nevertheless, conventional greedy DAMA systems and predictive DAMA systems do not always allocate resources in an optimal manner. For example, in a system in which calls have different priority levels, if available bandwidth is allocated for handling a high demand of low priority calls, future higher priority calls may be blocked, or calls in progress may require preempting for satisfying demands of higher priority calls. As another example, if the system allocates all available bandwidth to one ground node for handling a high call demand or a high predicted call demand, there might be a lack of bandwidth available for another ground node that will receive high call demand in the future.
What is needed is a system that measures trade-offs involved in allocating bandwidth between stations over time. Further, what is needed is a system that determines an optimal allocation of communication resources (i.e., bandwidth) that maximizes overall network system performance.

Decision-theoretic satellite communications system


A method of forming a registration pattern to enable detection of registration errors in an image forming device includes forming a first registration mark on a substrate at a first image forming station, and partially erasing the first registration mark formed on the substrate at a second image forming station to form the registration pattern. A method of automatically detecting the registration errors further comprises sensing the registration pattern, and detecting registration errors based on the registration pattern.

A single pass electrophotographic printer typically employs four image forming stations, each one responsible for printing one of four primary colors, typically cyan, magenta, yellow, and black. The individual images, known as separations, produced by each of the four image forming stations are combined to produce the final output image. In tandem print engines, the four image forming stations are aligned in the paper transport direction such that each separation is formed in succession on the copy sheet as the copy sheet is transported through each print station. Typically, a belt transports the copy sheet. In some printers, a belt serves as an intermediate transfer member (ITM). The image forming stations transfer the individual image separations onto the ITM to form a composite image on the ITM. The composite image is then transferred from the ITM to the copy sheet at a transfer station.
The alignment of the image separations produced by each image forming station is critical to producing a quality printed image. Various factors affect the proper alignment of the image forming stations, such as tolerances, wear, and thermal expansion/contraction. It can be expensive and impractical to control tolerances and wear in order to provide acceptable color registration. Therefore, many printers include a mechanism to detect and correct for color registration errors.
One technique used to detect color registration errors is to print a set of overlapping registration marks in two or more different colors and examine the result. Registration errors are detected by misalignment of the registration marks. Some registration patterns, exemplified by U.S. Pat. No. 6,408,156, are designed to indicate the degree of misregistration. In the '156 patent, the registration pattern comprises a series of bars printed in two different colors, one of which is usually black and the other of which is usually yellow, magenta or cyan. The bars of one color have varying degrees of offset from corresponding bars of the other color. The degree of misregistration is indicated by the set of bars that align.
In most prior art printers, detection of registration errors is performed manually by the user. The registration pattern is printed on an output sheet and the user visually examines the registration pattern to determine the amount of any registration errors. After determining the amount of any registration errors, the user enters correction data into the printer via the operator panel. Correction of registration errors by manual inspection of registration marks and manual entry of correction data into the printer is inconvenient for users.
Various methods for automatic detection and correction of color registration errors are known. One such method is to print the registration pattern on a transport belt or intermediate transfer belt, illuminate the registration pattern, and detect the amount of reflected light with an optical sensor. Optical detection works best when a black registration mark is printed over the top of a color (e.g. magenta, cyan, or yellow) registration mark on a dark belt to produce a composite registration pattern. When progressively greater amounts of the color toner are revealed from underneath a layer of black toner, the amount of light reflected by the color toner increases and is easily detected. Optical detection does not work as well when a color registration mark is printed over the top of a black registration mark on a dark belt because the black toner is closer in reflectance to the belt. Thus, revealing progressively larger amounts of black toner from underneath a layer of color toner produces little net difference in reflectance. The opposite is true if the paper transport belt or ITM belt is light.
In single pass electrophotographic printers, the order of the image forming stations affects optical sensing of registration patterns. Placing the black image forming station last is compatible with optical sensing of registration patterns on a dark belt. In some cases, however, it may be desirable to place the black image forming station first, making optical sensing of the registration patterns problematic. This problem may be solved by using a specular sensor. In general, black toner has a diffuse reflectance characteristic compared to the surface of the ITM belt, which is mostly specular. Thus, a specular sensor can be used to sense the loss of specular signals as black toner covers the bare belt. The use of a specular sensor for color registration, however, is undesirable because it may require separate sensors for color registration and toner density correction.

Method and apparatus for detecting registration errors in an image forming device