in vitro trials - mice infected with s. mansoni 
 cercariae ( le strain ) were sacrificed using sodium pentobarbital 3% ( 300 l / mice ) 
 and perfused according the technique of smithers and terry ( 1965 ) . the collected 
 worms were distributed into six - well - plates ( 4 pairs of worms / well ) and were kept in 
 culture medium rpmi-1640 supplemented with 5% foetal bovine serum , 100 g / ml 
 penicillin / streptomycin antibiotics . in the experimental group , the worms were 
 exposed to the compound for 24 h and maintained in an incubator at 37c 
 and 5% co2 . in the control group , the worms were kept under the same 
 conditions , but in the absence of the compound . afterwards , the worms were washed 
 with culture medium and maintained under the same previous conditions , but without 
 compounds until the end of the trial . observations were performed using an inverted 
 microscope and photos were taken daily for 1 - 24 h until seven days after the start 
 of the culture . the experiments 
 were performed in duplicate and repeated twice . 
 in vivo trials - female albino mice weighing about 20 g were 
 infected with 100  10 cercariae of s. mansoni ( le strain ) by 
 subcutaneous route . imatinib 
 ( glivec , novartis ) capsules of 400 mg were suspended in water and 
 administered orally . the drug administration , dose and treatment period varied 
 according to each experimental protocol . in order to analyse the drug activity , mice 
 were sacrificed by cervical dislocation and submitted to portal - hepatic perfusion 15 
 days after treatment followed by worm collection from mesenteric veins and liver . the number of worms in the liver were determined by organ compression under two 
 glass plates and counted using a stereomicroscope ( pellegrino & siqueira 1956 ) . oogram was made from 1 cm of the distal part of the small intestine and eggs were 
 classified according to the respective stages . the oogram was considered altered 
 when one or more stages of viable eggs were absent ( pellegrino et al . 1962 ) . in the control group , animals were infected as 
 described , but did not receive treatment . activity indicators were as follows : the average number of worms , percentage 
 distribution of worms in mesenteric veins and liver , presence of dead worms in the 
 liver and percentage of an altered oogram when compared to the control group ( pellegrino & katz 1968 ) . the results 
 obtained were compared by means of the students t test , p  0.05 
 being stipulated as significance level . ethics - all experiments were carried out in accordance with 
 brazilian regulation on the protection of animals . ethical approval for the study was obtained from the ethical committee for the use of experimental animals of the 
 oswaldo cruz foundation ( ceua l-018/09 ) . trials performed in vitro using 25 m showed that the intensity of movement of the 
 worms diminished and only three dead eggs were found 72 h after the worms were 
 removed from drug contact . with 50 m slow movements and interruption of egg - laying 
 were complete ( figure ) . at 100 m 
 morphological alterations and absence of egg - laying were observed . control worms 
 were very active with many eggs in all stages ( figure , table i ) . 
 in vitro experiments . a : control worms presenting eggs at all 
 developing stages ; b - d : worms exposed to imatinib ; b : worms exposed to 
 25 m with absence of eggs ; c : worms exposed to 50 m with absence of 
 eggs ; d : worms exposed to 100 m with absence of eggs , dead contracted 
 worm seven days after treatment . . 
 
 table iresults obtained in vitro experiments using adult schistosoma mansoni 
 worms exposed to imatinib imatinib ( m )   period of observation   observations   25   24h of contact   worms : live , normal morphology , motionless . .   50   24 h of contact   worms : live , normal morphology , motionless . .   100   24 h of contact   worms : live , normal morphology , motionless . .   -   control   worms : live , paired , normal movements and 
 morphology . 25   24 h after contact   worms : live , normal morphology , motionless . 50   24 h after contact   worms : live , normal morphology , motionless . 100   24 h after contact   worms : live , normal morphology , motionless . absence of eggs .   -   control   worms : live , paired , normal movements and 
 morphology . 25   48 h after contact   worms : live , normal morphology , motionless . 100   48 h after contact   worms : without movement , dead worms , altered 
 morphology . absence of eggs .   -   control   worms : live , paired , normal movements and 
 morphology , eggs at all development stages . imatinib used at single oral doses of 1,000 mg / kg / day , 500 mg / kg / day or 500 mg / kg / day 
 x 3 days for treating mice was found to be inactive , based on the mean of worms 
 recovered , distribution of the worms at the mesenteric vessels and liver . also , no 
 dead worms were found in the liver and no oogram alterations were observed ( table ii ) . table iiresults obtained in mice experimentally infected with 100  10 
 schistosoma mansoni cercariae ( le strain ) treated with imatinib by oral 
 route 45 days post - infection and sacrificed 15 days after treatment 
  animals ( n )   worm distribution ( % )   treatment schedule mg / kg / day x days treatedexamined mean worm burden mesenteryliver liver dead worm ( % )   oogram changes ( % )   1000 x 1   5   3   32.7   86.7   13.3   0   0   500 x 3   5   3   23.3   85.7   14.3   1.6   0   500 x 1   5   3   28.3   92.9   7.1   0   0   control   -   5   22.8   90.4   9.6   0   0 recently , it was very clearly demonstrated that imatinib , an anti - cancer compound , 
 produces alteration of morphology , pairing stability and survival of adult 
 s. mansoni in vitro ( beckmann 
 & grevelding 2010 ) . imatinib is a competitive antagonist of adenosine 
 triphosphate binding site , leading to inactivation of three tyrosine kinase ( pdgfr , 
 ber - abl and c - kit ) and interrupting downstream signalling processes ( savage & antman 2002 ) . also , it has been 
 reported that imatinib , by intra - peritoneal injection , have potent antifibrotic 
 activity both in suppressing and reversing s. mansoni induced liver 
 fibrosis ( el - agamy et al . when 
 imatinib was used in vitro the results showed activity on s. 
 mansoni with 10 m , but alterations were intense with 50 m or 100 m , 
 especially in females , but also in males . confocal laser scanning microscopy clearly 
 showed that the structure of the ovaries and oocytes was disordered . also , the 
 vitellarium was altered in the females treated with the highest dose ( 100 m ) . on 
 the male worms reduction in size of the testicular lobes on spermatocytes were 
 observed . imatinib produces severe gastrodermis alterations in worms of both sexes 
 ( beckmann & grevelding 2010 ) . it is interesting to remark that the protein tyrosine kinases as potential targets 
 against human schistosomiasis has been suggested by several authors ( dissous et al . 2007 , knobloch et al 2007 ) against plasmodium 
 falciparum ( ward et al . 2004 ) , trypanosomes and 
 leishmania ( naula et al . 2005 ) and ecchinococcus 
 multilocularis larvae ( hemer & 
 brehm 2012 ) . several compounds that are protein kinase inhibitors have 
 been approved for cancer treatment in humans ( cohen 
 2009 ) . our present results are in accordance with beckmann 
 and grevelding ( 2010 ) as far as in vitro activity is concerned . we used 
 only optical microscopy for assessing the decrease in movements , worm separation of 
 couples and stop of egg - laying , starting with imatinib at the dose of 25 m , being 
 more active at 50 m and 100 m . the interruption of egg - laying in vitro is a phenomenon that has been observed with 
 other active compounds and can be considered an important sign for detecting 
 anti - schistosomal activity . it is interesting to remark that also in 
 vivo , in mice experimentally infected with s. 
 mansoni or schistosoma japonicum , the oogram method , 
 which is the description of different egg stages found at the intestinal wall , has 
 been used for drug screening since 1960s ( pellegrino 
 et al . 1962 ) . when imatinib was orally administered to mice experimentally infected with s. 
 mansoni , with the protocol followed in this study , no 
 activity was detected , even at the doses of 1,000 mg / kg or 500 mg / kg that can be 
 considered very high , when compared to the active dose used for treatment of 
 clinical cases of myeloma leukaemia that is 400 mg per day . ( 2004 ) found that the mean fraction of imatinib in 
 plasma ( fp ) was 50% in mouse and up to 92% in acute lymphatic leukaemia 
 ( aml ) patients . similarly , fp for cgp74588 , the primary metabolite of 
 imatinib , was 70% in mouse and 90% in some aml patients . the failure of imatinib 
 treatment can not yet be explained , since the dosage of imatinib administered was 
 very high , over 50 times higher than the clinical dose for daily treatment . again , 
 the discrepancy between the results obtained when comparing antischistosomal agents 
 in vitro and in vivo has already been described ( arajo et al . although in vitro studies are useful to generate 
 knowledge , they are obviously limited . a medication may change depending on the 
 specific biological processes of the organism . in vitro experiments are a simulation 
 of the reality and they must be tied to in vivo studies , to support scientific 
 research ( andersen et al .
imatinib , a drug used for treatment of human chronic myeloid leukaemia , due to 
 its activity against protein kinases , has been also evaluated in vitro against 
 schistosoma mansoni showing high schistosomicidal activity . 
 in the present experiments imatinib activity in vitro 
 was confirmed at the doses 
 of 25 m , 50 m and 100 m . 
 the first drug activity observed with the lower dose 
 was interruption of egg - laying and with the higher dosages was the death of the 
 worms . in mice infected with s. mansoni no activity 
 was found 
 even with 1,000 mg / kg / day , 500 mg / kg / day , single oral dose or when administered 
 for three consecutive days . 
 this is another example of the difference of results 
 related to in vitro and in vivo trials using s. mansoni 
 worms .