High-throughput segmentation of unmyelinated axons by deep learning.
Axonal characterizations of connectomes in healthy and disease phenotypes are surprisingly incomplete and biased because unmyelinated axons, the most prevalent type of fibers in the nervous system, have largely been ignored as their quantitative assessment quickly becomes unmanageable as the number of axons increases. Herein, we introduce the first prototype of a high-throughput processing pipeline for automated segmentation of unmyelinated fibers. Our team has used transmission electron microscopy images of vagus and pelvic nerves in rats. All unmyelinated axons in these images are individually annotated and used as labeled data to train and validate a deep instance segmentation network. We investigate the effect of different training strategies on the overall segmentation accuracy of the network. We extensively validate the segmentation algorithm as a stand-alone segmentation tool as well as in an expert-in-the-loop hybrid segmentation setting with preliminary, albeit remarkably encouraging results. Our algorithm achieves an instance-level [Formula: see text] score of between 0.7 and 0.9 on various test images in the stand-alone mode and reduces expert annotation labor by 80% in the hybrid setting. We hope that this new high-throughput segmentation pipeline will enable quick and accurate characterization of unmyelinated fibers at scale and become instrumental in significantly advancing our understanding of connectomes in both the peripheral and the central nervous systems.


The spin distribution in low-spin iron porphyrins.
In many low-spin (S = 1/2) iron porphyrin derivatives, electron spin resonance (ESR) spectra indicate that one of the d(pi) orbitals of iron, either a d(xz) or d(yz), depending on the axial ligands of the porphyrin complex as well as their orientation, is essentially singly occupied; the unpaired electron is almost completely located at the metal. In contrast, nuclear magnetic resonance (NMR) and electron nuclear double resonance (ENDOR) spectroscopy convincingly show that a significant share of the unpaired electron is delocalized. This apparent contradiction is explained by the present density-functional-theory (DFT) calculations performed on a heme a model as well as on bis-imidazole-ligated iron porphyrin without substituents. The calculations show that the integrated spin density at the iron atom is nearly one, in agreement with the ESR measurements. However, significant areas with opposite (beta) spin are found along the Fe-N bond axes, thus evoking a need for additional alpha-spin density to be present in the porphyrin ring, ring substituents, and the axial ligands to keep the net amount of unpaired spin exactly one. The gross spin density, that is, the sum of unpaired alpha and beta spins, amounts to about 1.3 electrons. It seems that the degree to which alpha and beta spin dominate in different regions of the heme structure, as evidenced in these calculations, has not been previously observed.


Arterial embolization for salvage of hepatic artery infusion pumps.
Hepatic artery infusion pumps (HAIPs) ideally provide for homogenous perfusion of the liver with chemotherapeutic agents. Perfusion of extrahepatic organs or asymmetric liver perfusion (ie, "misperfusion") is diagnosed by nuclear scintigraphy and precludes the use of HAIPs. The purpose of this study is to report experience in salvaging HAIPs with arterial embolization. A single-center HAIP database was retrospectively reviewed for cases from 1999 to 2005 to identify patients who underwent angiography to treat misperfusion documented by nuclear scintigraphy. Patient demographics, nuclear scintigraphic findings before and after embolization, angiographic findings, embolization variables, and outcomes were recorded. Technical success (defined by cessation of flow to the vessel responsible for misperfusion) and clinical success (ie, successful use of the pump) were calculated. During the study period, 475 HAIPs were implanted. Of those, 43 (9%) had abnormal nuclear scintigraphic findings of misperfusion, but only 32 (7%) had angiographic abnormalities. In eight of 32 cases, hepatic arterial thrombosis and extravasation at the catheter tip were found, which precluded salvage by embolization. In 24 of 32 cases, a vessel presumed responsible for the misperfusion was identified and targeted for embolization. Technical success and clinical success were achieved in 21 of 24 patients (87.5%) and 19 of 24 patients (79%), respectively, who underwent 27 embolization procedures. The three technical failures (12.5%) were the result of inability to catheterize the identified vessel. Percutaneous arterial embolization of a vessel to correct misperfusion shown by nuclear scintigraphy is safe and effective. This approach can be expected to result in HAIP salvage in the majority of patients.


Influence of irradiation time on effect of a light-activated dentin-bonding agent.
The marginal adaptation to dentin cavities of a microfilled restorative resin was measured with and without previous use of a light-activated dentin-bonding agent. The investigation was carried out on butt-joint cavities prepared in extracted human teeth. Increasing the irradiation time of the bonding agent from 10 to 80 sec reduced significantly both the width and the extent of the marginal contraction gap.


Dry-reagent-based PCR as a novel tool for the rapid detection of Clostridium spp.
Improved conventional PCR techniques are required for the rapid on-site detection of human and animal diseases. In this context, a PCR method using dry-stored reagents intended for the detection of Clostridium spp. is presented. Basic PCR reagents (BSA, PCR buffer, MgCl₂ and primers), which were dried on polyolefin matrices, showed stability at ambient temperatures for up to 10 months without any loss of functionality. An outstanding advantage of our amelioration is the elimination of PCR process errors caused by the improper storage and handling of liquid reagents. Moreover, our PCR-based amplification can be performed in less than 30 min, saving time compared with conventional detection methods. Thus, dry-reagent-based PCR is implementable in a suitcase-like modular device for the rapid on-site detection of microbial pathogens such as blackleg of ruminants caused by Clostridium chauvoei.