Ultrastructural alterations in Schistosoma mansoni juvenile and adult male worms after in vitro incubation with primaquine

BACKGROUND Praziquantel has been cited as the only drug for treating schistosomiasis. However, concerns over drug resistance have encouraged the search for novel drug leads. The antimalarial drug primaquine possesses interesting anti-schistosmal properties. OBJECTIVES This study is the first to document the potential role of primaquine as a schistosomicide and the ultrastructural changes induced by primaquine on juvenile or adult male worms of Schistosoma mansoni. METHODS Ultrastructural alterations in the tegumental surface of 21-day-old juvenile and adult male worms of S. mansoni were demonstrated following primaquine treatment at different concentrations (2, 5, 10, 15, and 20 µg/mL) and incubation periods (1, 3, 6, 24, and 48 h) in vitro, using both scanning and transmission electron microscopy. FINDINGS At low concentrations (2, 5, and 10 µg/mL) both juvenile and adult male worms were alive after 24 h of incubation, whereas contraction, paralysis, and death of all worms were observed after 24 h of drug exposure at 20 µg/mL. The tegument of juvenile and adult male worms treated with primaquine exhibited erosion, peeling, and sloughing. Furthermore, extensive damage of both tegumental and subtegumental layers included embedded spines, and shrinkage of muscles with vacuoles. The in vitro results confirmed that primaquine has dose-dependent effects with 20 µg/mL as the most effective concentration in a short incubation period. MAIN CONCLUSIONS The schistosomicidal activity of primaquine indicates that this drug possesses moderate in vitro activity against juvenile and adult male worms, since it caused high mortality and tegumental alterations. This study confirmed that the antimalarial drug primaquine possesses anti-schistosomal activity. Further investigation is needed to elucidate its mechanism of action.

Ultrastructural study of morphological changes in Schistosoma mansoni after in vitro exposure to the monoterpene rotundifolone

ABSTRACT INTRODUCTION: Schistosomiasis, a parasitic disease caused by trematode flatworms of the genus Schistosoma, affects more than 200 million people worldwide, and its control is dependent on a single drug, praziquantel. Here, we report the in vitro effect of rotundifolone, a monoterpene isolated from Mentha x villosa (Lamiaceae), on Schistosoma mansoni adult worms. METHODS: The in vitro effect of rotundifolone on adult Schistosoma mansoni was evaluated by analysis of behavior and mortality and through a scanning electron microscopic analysis of ultrastructural changes in the tegument of the worms. RESULTS: At concentrations of 3.54 and 7.09μg/mL-1 rotundifolone, no worm mortality was observed at any of the sampling intervals. A minor reduction in movement of the tail, suckers, and gynecophoral canal membrane was observed after 96 h of exposure to 7.09μg/mL-1 rotundifolone. At 70.96μg/mL-1, a lack of movement was observed from 72h onwards and all worms were deemed dead; similar effects were observed at 48h with 177.4μg/mL-1, and at 24h with 354.8μg/mL-1 and 700.96μg/mL-1. Rotundifolone also caused death of all parasites and separation of coupled pairs into individual males and females after 24h at 354.8μg/mL-1. CONCLUSIONS: The main changes in the tegument induced by the different ROT treatments were: after 24h incubation, bubble lesions spread over the entire body and loss of tubercles occurred in some regions of the ventral region.

Synthesis and biological evaluation of novel imidazolidine derivatives as candidates to schistosomicidal agents

ABSTRACT Introduction: Schistosomiasis is an infectious parasitic disease caused by trematodes of the genus Schistosoma, which threatens at least 258 million people worldwide and its control is dependent on a single drug, praziquantel. The aim of this study was to evaluate the anti-Schistosoma mansoni activity in vitro of novel imidazolidine derivatives. Material and methods: We synthesized two novel imidazolidine derivatives: (LPSF/PTS10) (Z)-1-(2-chloro-6-fluorobenzyl)-4-(4-dimethylaminobenzylidene)-5-thioxoimidazolidin-2-one and (LPSF/PTS23) (Z)-1-(2-chloro-6-fluoro-benzyl)-5-thioxo-4-(2,4,6-trimethoxy-benzylidene)-imidazolidin-2-one. The structures of two compounds were determined by spectroscopic methods. During the biological assays, parameters such as motility, oviposition, mortality and analysis by Scanning Electron Microscopy were performed. Results: LPSF/PTS10 and LPSF/PTS23 were considered to be active in the separation of coupled pairs, mortality and to decrease the motor activity. In addition, LPSF/PTS23 induced ultrastructural alterations in worms, after 24 h of contact, causing extensive erosion over the entire body of the worms. Conclusion: The imidazolidine derivatives containing the trimetoxy and benzylidene halogens showed promising in vitro schistosomicidal activity.

In vitro antischistosomal activity of venom from the Egyptian snake Cerastes cerastes

Abstract INTRODUCTION: We studied the potential in vitro antischistosomal activity of Cerastes cerastes venom on adult Schistosoma mansoni worms. METHODS: Live specimens of the horned viper snake, C. cerastes were collected from the Aswan Governorate (Egypt). Venom was collected from snakes by manual milking. Worms of S. mansoni were obtained from infected hamsters by perfusion and isolated from blood using phosphate buffer. Mortality rates of worms were monitored after 3 days of exposure to snake venom at LC50 and various sublethal concentrations (10, 5, 2.5µg/ml). Scanning electron microscopy was used to investigate tegumental changes in treated worms after exposure to LC50 doses of venom. RESULTS: The LC50 of C. cerastes venom was 21.5µg/ml. The effect of C. cerastes venom on Schistosoma worms varied according to their sex. The mortality rate of male and female worms after 48-h exposure was 83.3% and 50%, respectively. LC50 of C. cerastes venom induced mild to severe tegumental damage in Schistosoma worms in the form of destruction of the oral sucker, shrinkage and erosion of the tegument, and loss of some tubercle spines. CONCLUSIONS: The present study demonstrated that C. cerastes venom exerts potential in vitro antischistosomal activity in a time and dose-dependent manner. These results may warrant further investigations to develop novel schistosomicidal agents from C. cerastes snake venom.

THE SUSCEPTIBILITY OF RECENT ISOLATES OF Schistosoma mansoni TO PRAZIQUANTEL

Introduction: Schistosomiasis is a chronic disease caused by trematode flatworms of the genus Schistosoma and its control is dependent on a single drug, praziquantel (PZQ), but concerns over PZQ resistance have renewed interest in evaluating the in vitro susceptibility of recent isolates of Schistosoma mansoni to PZQ in comparison with well-established strains in the laboratory. Material and methods: The in vitro activity of PZQ (6.5-0.003 µg/mL) was evaluated in terms of mortality, reduced motor activity and ultrastructural alterations against S. mansoni. Results: After 3 h of incubation, PZQ, at 6.5 µg/mL, caused 100% mortality of all adult worms in the three types of recent isolates, while PZQ was inactive at concentrations of 0.08-0.003 µg/mL after 3 h of incubation. The results show that the SLM and Sotave isolates basically presented the same pattern of susceptibility, differing only in the concentration of 6.5 µg/mL, where deaths occurred from the range of 1.5 h in Sotave and just in the 3 h range of SLM. Additionally, this article presents ultrastructural evidence of rapid severe PZQ-induced surface membrane damage in S. mansoni after treatment with the drug, such as disintegration, sloughing, and erosion of the surface. Conclusion: According to these results, PZQ is very effective to induce tegument destruction of recent isolates of S. mansoni.

ULTRASTRUCTURAL CHANGES IN Schistosoma mansoni MALE WORMS AFTER in vitro INCUBATION WITH THE ESSENTIAL OIL OF Mentha x villosa Huds

Introduction: The essential oil Mentha x villosa (MVEO) has a wide range of actions, including antibacterial, antifungal, antiprotozoal and schistosomicidal actions. The present study aimed to investigate the ultrastructural changes of MVEO on the tegument of adult Schistosoma mansoni. Materials and Methods: Different concentrations of MVEO were tested on S. mansoni adult worms in vitro. Ultrastructural changes on the tegument of these adult worms were evaluated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results: The MVEO caused the death of all worms at 500 μg mL-1 after 24 h. After 24h of 500 μg mL-1 MVEO treatment, bubble lesions were observed over the entire body of worms and they presented loss of tubercles in some regions of the ventral portion. In the evaluation by TEM, S. mansoni adult worms treated with MVEO, 500 μg mL-1, presented changes in the tegument and vacuoles in the syncytial matrix region. Glycogen granules close to the muscle fibers were visible. Conclusion: The ability of MVEO to cause extensive ultrastructural damage to S. mansoni adult worms correlates with its schistosomicidal effects and confirms earlier findings with S. mansoni.

Artesunate effect on Schistosome thioredoxin glutathione reductase and cytochrome-C peroxidase as new molecular targets in Schistosoma mansoni infected mice

Schistosomiasis remains one of the most important parasitic diseases. Extensive use of praziquantel [PZQ] with concerns about possibility of drug resistance development, unavailability of an applicable vaccine, and absence of a reasonable alternative to PZQ, all represent a real challenge in control of schistosomiasis. Artemisinin derivatives are promising anti-schistosomal compounds, but their molecular mechanism of action on schistosomes is still not well defined. This study investigated the possible effect of artesunate [ART] on schistosome thioredoxin glutathione reductase [TGR] and cytochrome c peroxidase [CcP] in Schistosoma mansoni-infected mice. The animals used were divided into four groups. Group I: infected untreated group [control group]; group II: infected then treated with ART; group III: infected then treated with PZQ; and group IV: infected then treated with both ART and PZQ. ART was given orally in four doses, each of 300 mg/kg starting at 14th day post-infection [PI] and then every 2 weeks. PZQ was given orally in a single dose of 600 mg/kg at 42nd day PI. Then all mice were subjected to the following: adult S. mansoni worm count at 10 weeks PI, tissue egg count in liver and estimation of TGR and CcP mRNA expression in S. mansoni adult worms by semi-quantitative real time-PCR [rt-PCR]. Semi-quantitative rt-PCR values revealed that treatment with ART caused significant decrease in expression of schistosome TGR and CcP in contrast to PZQ which did not cause significant change in their expression. In addition, there was more reduction in total and female worm counts in ART-PZQ treated group than in other treated groups. Moreover, complete disappearance [100%] of tissue eggs was recorded in ART-PZQ treated group with a respective reduction rate of 95.9% and 68.4% in ART- and PZQ-treated groups. The current study elucidated for the first time that anti-schistosomal mechanism of action of ART is mediated via reduction in expression of schistosome TGR and CcP. Linking these findings, the addition of ART to PZQ could achieve complete cure outcome in treatment of schistosomiasis

Ultrastructural study on the morphological changes to male worms of Schistosoma mansoni after in vitro exposure to allicin / Estudo ultraestrutural das alterações morfológicas de vermes machos de Schistosoma mansoni após exposição in vitro à alicina

INTRODUCTION: Garlic has a wide range of actions, including antibacterial, antiviral, antifungal, antiprotozoal and anthelmintic actions. This antiparasitic activity has been attributed to allicin, which is the main constituent of garlic. The present study aimed to investigate the in vitro activity of allicin on the tegument of adult Schistosoma mansoni worms using scanning electron microscopy. METHODS: Swiss Webster mice were infected with S. mansoni cercariae (100 per mouse) and sacrificed 50 days later to acquire the adult worms. These worms were collected by perfusion and placed in RPMI medium 1,640 at 37°C before transferring to RPMI media containing 0 (control), 5, 10, 15 and 20mg/mL of allicin, where they were incubated for 2h. The worms were fixed in 2.5 percent glutaraldehyde solution, washed twice, post-fixed in osmium tetroxide, washed twice and then dehydrated with ascending grades of ethanol. The samples were air-dried, mounted on stubs, gold coated in an ion sputtering unit and viewed using a scanning electron microscope. RESULTS: A concentration of 5mg/mL caused wrinkling in the tegument; a concentration of 10mg/mL resulted in changes to tubercles and loss or modification of spines. With 15 and 20mg/mL increasing damage to the tegument could be seen, such as vesicle formation and the presence of ulcers. CONCLUSIONS: These findings demonstrate the effect of allicin on adult S. mansoni worms and indicate that most of the changes occur at concentrations greater than that normally indicated for treatment.

INTRODUÇÃO: O alho apresenta uma ampla gama de ações, incluindo antibacteriana, antiviral, antifúngico, antiprotozoário e anti-helmíntico. Esta atividade antiparasitária tem sido atribuída à alicina, que é o principal constituinte do alho. O presente estudo teve como objetivo investigar a ação in vitro da alicina no tegumento de vermes adultos de Schistosoma mansoni utilizando a microscopia eletrônica de varredura. MÉTODOS: Camundongos Swiss Webster foram infectados com cercárias de S. mansoni (100 por camundongo) e sacrificados 50 dias depois para aquisição de vermes adultos. Estes vermes foram coletados por perfusão e colocados em meio RPMI 1.640 a 37°C antes de transferir para o meio RPMI contendo 0 (controle), 5, 10, 15 e 20mg/mL de alicina, onde eles foram incubados por 2h. Os vermes foram fixados em uma solução de glutaraldeído a 2,5 por cento, lavados duas vezes, pós-fixados em tetróxido de ósmio, lavados duas vezes e então desidratados em séries crescentes de etanol. As amostras foram secadas, montadas em stubs, metalizadas em ouro e visualizadas utilizando o microscópio eletrônico de varredura. RESULTADOS: A concentração de 5mg/mL causou o enrugamento do tegumento; a concentração de 10mg/mL resultou em alterações nos tubérculos e perda ou modificações nos espinhos. Com 15 e 20mg/mL crescentes danos no tegumento pode ser visto, tais como formação de vesículas e presença de úlceras. CONCLUSÕES: Esses resultados demonstram os efeitos da alicina nos vermes adultos de S. mansoni e indicam que a maioria das alterações ocorrem numa concentração maior do que a normalmente indicada para o tratamento.

Identificação e caracterização computacional de proteínas do tipo IUP no proteoma predito de Schistosoma mansoni / Caracterization and identification proteins of computational of the type IUP in predicted proteoma of the Schistosoma mansoni

A relação entre estrutura e função protéica é um dos conceitos mais bem estabelecidos da biologia molecular. O acúmulo de evidências experimentais, cujos primeiros trabalhos datam de 1890, suportam essa hipótese com grande embasamento científico. Apesar da existência de evidências de mais de um século de estudos, somente no inicio da década de 90 começaram a surgir trabalhos mostrando de forma conclusiva a existência de proteínas funcionalmente ativas, mas incapazes de manter uma conformação estável em condições fisiológicas. Tais proteínas, hoje conhecidas como IUPs (do inglês Intrinsically Unstructured Proteins) estão envolvidas em importantes processos de saúde e doenças, tais como o câncer e diversos processos de interação parasito/hospedeiro. A presente dissertação tem como proposta o estabelecimento de um pipeline computacional visando à avaliação dos diferentes algoritmos de predição de desordem estrutural, seu desempenho e a posterior aplicação dessa ferramenta no estudo in silico do conteúdo de IUPs presentes no proteoma predito de Schistosoma mansoni. Complementarmente, foi desenhado um banco de dados MySQL capaz de albergar toda a informação de desordem estrutural juntamente com diferentes dados de caracterização das IUPs para S. mansoni.

Foram analisados um total de 10.417 proteínas, 7.373 predições de desordem estrutural, mais de 24.600 predições de características estruturais e funcionais, desenvolvidos 21 scripts, e todas essas predições e scripts desenvolvidos foram integrados em um pipeline totalmente automático e inédito para. análise de desordem estrutural. Nossas análises de sensibilidade e especificidade implementadas pela análise de gráficos ROC e pela integração de resultados utilizando bancos de dados relacionais indicam que a predição integrativa (consenso de quatro diferentes metodologias de predição) de desordem estrutural apresenta um ganho de 40% na correta identificação de regiões desordenadas se comparada às predições de cada metodologia individualmente. Aproximadamente 5,5% das regiões desordenadas identificadas tiveram suas coordenadas limítrofes ajustadas após comparação com as coordenadas de domínios conservados. Nossos resultados indicam que aproximadamente 33,6% do proteoma predito de S. mansoni apresenta desordem estrutural. Destas, 2% apresentam domínios transmembrana e 7% apresentam peptídeo sinal. A comparação do perfil funcional das IUPs com as proteínas globulares de S. mansoni demonstra uma maior proporção de IUPs envolvidas em processos de regulação celular e componentes extracelulares.

Identificação e caracterização computacional de proteínas do tipo IUP no proteoma predito de Schistosoma mansoni

A relação entre estrutura e função protéica é um dos conceitos mais bem estabelecidos da biologia molecular. O acúmulo de evidências experimentais, cujos primeiros trabalhos datam de 1890, suportam essa hipótese com grande embasamento científico. Apesar da existência de evidências de mais de um século de estudos, somente no inicio da década de 90 começaram a surgir trabalhos mostrando de forma conclusiva a existência de proteínas funcionalmente ativas, mas incapazes de manter uma conformação estável em condições fisiológicas. Tais proteínas, hoje conhecidas como IUPs (do inglês Intrinsically Unstructured Proteins) estão envolvidas em importantes processos de saúde e doenças, tais como o câncer e diversos processos de interação parasito/hospedeiro. A presente dissertação tem como proposta o estabelecimento de um pipeline computacional visando à avaliação dos diferentes algoritmos de predição de desordem estrutural, seu desempenho e a posterior aplicação dessa ferramenta no estudo in silico do conteúdo de IUPs presentes no proteoma predito de Schistosoma mansoni. Complementarmente, foi desenhado um banco de dados MySQL capaz de albergar toda a informação de desordem estrutural juntamente com diferentes dados de caracterização das IUPs para S. mansoni.

Foram analisados um total de 10.417 proteínas, 7.373 predições de desordem estrutural, mais de 24.600 predições de características estruturais e funcionais, desenvolvidos 21 scripts, e todas essas predições e scripts desenvolvidos foram integrados em um pipeline totalmente automático e inédito para. análise de desordem estrutural. Nossas análises de sensibilidade e especificidade implementadas pela análise de gráficos ROC e pela integração de resultados utilizando bancos de dados relacionais indicam que a predição integrativa (consenso de quatro diferentes metodologias de predição) de desordem estrutural apresenta um ganho de 40% na correta identificação de regiões desordenadas se comparada às predições de cada metodologia individualmente. Aproximadamente 5,5% das regiões desordenadas identificadas tiveram suas coordenadas limítrofes ajustadas após comparação com as coordenadas de domínios conservados. Nossos resultados indicam que aproximadamente 33,6% do proteoma predito de S. mansoni apresenta desordem estrutural. Destas, 2% apresentam domínios transmembrana e 7% apresentam peptídeo sinal. A comparação do perfil funcional das IUPs com as proteínas globulares de S. mansoni demonstra uma maior proporção de IUPs envolvidas em processos de regulação celular e componentes extracelulares.

Morphological aspects of Schistosoma mansoni adult worms isolated from nourished and undernourished mice: a comparative analysis by confocal laser scanning microscopy

Malnutrition hampers the course of schistosomiasis mansoni infection just as normal growth of adult worms. A comparative morphometric study on adult specimens (male and female) recovered from undernourished (fed with a low protein diet - regional basic diet) and nourished (rodent commercial laboratory food, NUVILAB) white mice was performed. Tomographic images and morphometric analysis of the oral and ventral suckers, reproductive system and tegument were obtained by means of confocal laser scanning microscopy. Undernourished male specimens presented smaller morphometric values (length and width) of the reproductive system (first, third and last testicular lobes) and thickness of the tegument than controls. Besides that, it was demonstrated that the dorsal surface of the male worms bears large tubercles unevenly distributed, but kept grouped and flat. At the subtegumental region, vacuolated areas were detected. It was concluded that the inadequate nutritional status of the vertebrate host has a negative influence mainly in the reproductive system and topographical somatic development of male adult Schistosoma mansoni, inducing some alterations on the structure of the parasite

Effects of the desiccation on Biomphalaria tenagophila (Orbigny, 1835) (Mollusca) infected by Schistosoma mansoni Sambon, 1907

Specimens of Biomphalaria tenagophila exposed to miracidia of Schistosoma mansoni were submitted to different desiccation periods as follows: group I: 24 h after exposure, desiccated for 28 days; group II: after cercariae elimination, desiccated for 7 days; group III: 21 days after exposure, desiccated for 7 days; group IV: 14 days after exposure, desiccated for 14 days; group V: 7 days after exposure, desiccated for 21 days. From the obtained data it was verified that desiccation was not capable of interrupting the development of larvae of S. mansoni in mollusks. A delay in the development of S. mansoni larvae in groups I, III, IV and V was observed. A pause was verified in the development of S. mansoni larvae in groups II, III, IV and V. Some larvae, in groups I, III, IV and V, did not suffer as a result of desiccation and continued their development. Larvae in the cercariae stage were shown to be more sensitive to desiccation. It was possible to obtain clearing of mollusks infected by sporocysts II and cercariae using a period of 7 days of desiccation

Topographical alterations and increased antigenic exposure at the outer tegumental surface of schistosoma mansoni adult worms as a consequence of praziquantel treatment and UV -irradiation [in vitro]

Schistosoma mansoni adult worms harvested from Swiss albino mice infected with 200 cercariae/mouse, seven weeks post infection was subjected to UV-irradiation and praziquantel [PZQ] treatment. Treated worms were processed for scanning electron microscopy, light microscopy and immunofluorescence technique. Results demonstrated that in vitro PZQ-treatment or UV-irradiation induced severe surface tegumental damage, disruption, and corrugation of tubercle spaces. Regression of spines from the dorsal surface of the tegument was also observed. A variety of histological changes have been observed post in vitro PZQ-treatment in the structure of the tegumental and subtegumental tissues. Focal surface swelling and erosion together with marked loss of spines from the tegumental tubercles were observed in addition to slight vaculation in subtegumental tissues. The extent of tegumental damage was apparent and severe in PZQ-treatment rather than UV-irradiation, which showed relatively, moderate damage. In the immunofluorescence assay treated and non-treated control worms were probed with infected mouse serum, and incubated with conjugated [FITC] anti mouse IgG monoclonal antibody. An intensive fluorescent reaction was observed at the tegumental surface of worms pre-treated with praziquantel. Relatively moderate reaction was observed with UV-irradiated worms. Non-treated control worms showed mild positive reaction. This indicates an increase in the exposure of antigenic epitopes at the tegument of the treated worms than non-treated control worms. It is concluded that the induced damage in the tegumental surface and the exposure of antigenic epitopes as consequence of either PZQ-treatment or UV-irradiation could play a central and essential role in the propagation of the host-dependent effect or immune mechanism[s] which lead to the death and elimination of adult PZQ-treated or UV-irradiated worms in infected hosts

Morphological study of adult male worms of Schistosoma mansoni Sambon, 1907 by scanning electron microscopy

Tubercles, spines and sensory receptors are the most studied structures of adult male worms of Schistosoma mansoni isolated in other countries. The purpose of this investigation was to properly define these structures in Brazilian worms. Specimens 7-8 weeks after infection were recovered from albino SW mice and from a wild rodent (Nectomys squamipes) and processed for scanning electron microscopy studies. Photomicrographs of the anterior region with the aspects related to the outer and inner regions of both suckers were considered. The ventral portion of the middle region was represented by the anterior of gynaecophoric canal while the dorsal surface was studied in its ventral and dorsal regions mainly focusing the aspect of the tubercles, spines and sensorial papillae. The outer surface of the oral sucker is spiny and spines are bigger, sharp with sensory receptors in their posterior edge. Tubercles with spines or receptors are more concentrated in the middle region and in one of the margins of the gynaecophoric canal. An excretory pore-like structure in the posterior portion was observed. The gynaecophoric canal has few sensory structures, spines broadned in their mid-region and are sharp pointed at the distal end. It was concluded that the presently studied characters are similar to those previously reported.

Ultrastructural and biochemical detection of biotin and biotinylated polypeptides in Schistosoma mansoni

Biotinylation is proposed for the identification of surface proteins in Schistosoma mansoni using the streptavidin-HRP conjugate for the detection of labeled polypeptides. However, control samples also showed several endogenous biotinylated polypeptides. In an attempt to determine the possibility of monspecific binding between the streptavidin-HRP conjugate and polypeptides from S. mansoni, the conjugate was blocked with biotinamidecaproate-N-hydroxysuccinimide ester (BcapNHS) before biotin-streptavidin blotting. No bands were detected on the nitrocellulose sheet, demonstrating the especific recognition of biotin by the streptavidin present in the conjugate. Whole cercariae and cercarial bodies and tails showed several endogenous biotinylated polypeptides. The biotin concentration was 13 mug/190,000 cercariae. Adult worms presented less endogenous biotinylated polypeptides than cercariae. These results may be due to changes in the environment from aerobic to anaerobic conditions when cercarial bodies (schistosomula) are transformed into adult worms and a decrease in CO2 production may occur. Cercariae, cercarial bodies and adult male worms were examined by transmission electron microscopy employing an avidin-colloidal gold conjugate for the detection of endogenous biotin. Gold particles were distributed mainly on the muscle fibers, but dispersed granules were observed in the tegument, mitochondria and cytosol. The discovery of endogenous biotin in S. mansoni should be investigate in order to clarify the function of this vitamin in the parasite.

Effect of two trematodicidal drugs on the morphology and tegumentary ultrastructure of schistosoma mansoni

A study of the effects on the tegument of S. mansoni adult worm following in vivo praziquantel and triclabendazole treatment was performed. The topographic changes observed in treated adults were in the form of bleeds and vesicles covering the surface of the worm with disappearance of spines and disorganization of the tegument. The ventral sucker was completely retracted in praziquantel treated worms, however in triclabendazole, the oral sucker was mainly affected. The difference in tegumental changes between the two drugs may be due to the difference in their mode of action

Pathologic and ultrastructure characterization of two different strains of schistosoma mansoni

This study was performed on albino mice infected with both Egyptian and Saudi Schistosoma mansoni strains to investigate the characteristic differences between them. It was found that at the 8th week post-infection, the highest amount of egg deposition and granuloma formation was present in the liver of infected mice with the Egyptian strain, while it was highest in the small intestine of those infected with the Saudi strain, followed by the liver and the large intestine. Although no prominent histopathologic differences were detected in the cellular and tissue reactions in the resulting granulomata surrounding eggs, yet marked differences were observed in the surface topography of the tegument and distribution of papillae, pattern of ridges, microvilli and spines of both strains. These differences were more pronounced in males

Evaluation of spleen cell population and effect of splenectomy on granuloma modulation in BALB/c mice infected with Schistosoma mansoni

A kinetic study of the cells present in the spleen of BALB/c mice infected with Schistosoma mansoni was carried out. The lymphocytes were evaluated phenotypically with monoclonal antibodies and the effect of splenectomy on the modulation of periovular granuloma was also investigated. The infected mice had proportional increases in the numbers of neutophils, plasma cells, macrophages and eosinophils in the spleen. The largest number of neutrophil, plasma cells and macrophage were found between the 8th and the 12th week of infection, while the amount of eosinophils were higher later on, around the 20th week. The lymphocytes phenotipically characterized as Thy 1.2, Lyt 1.2 (CD4) increased mildly in proportional numbers. However, the percentage of lymphocytes with the Lyt 2.2 (CD8) phenotype, which is characteristic of supressor and cytotoxic T cells, increased significantly with the progress of the disease. The numbers of B lymphocytes, which comprise 50% of the mononuclear cells present in the spleen, increased significantly till the 16th week they began to decrease. The mean diameters of periovular granulomas were comparatively similar in both experimental groups (splenectomized and non-splenectomized mice). However, the evolutive types of granuloma (exudative, intermediate and fibrous) in splenectomized mice were proprtionally different from those of non splenectomized mice in the 16th and 24th week of infection. It is inferred that lymphonodes or other secondary lymphoide organs, in the abscence of the spleen, assume a modulating action on periovular granulomas, although the evolution of the granulomas is somehow delayed in splenectomized mice