Biomedical subjects

B Marchand

Publications and source records attributed to B Marchand.

At least 37 records · Page 2Linked to original sources

PubMed1998

Ultrastructure of spermiogenesis of Dipylidium caninum (Cestoda, Cyclophyllidea, Dipylidiidae), an intestinal parasite of Canis familiaris.

We describe for the first time the ultrastructure of spermiogenesis of a representative of the family Dipylidiidae, Dipylidium caninum. Spermiogenesis begins with the formation of a differentiation zone. This conical area presents two centrioles with associated striated roots. One of the centrioles develops a flagellum and posteriorly a proximodistal fusion is produced between the axoneme and a median cytoplasmic process. In a final stage of spermiogenesis a condensation of electron-dense material between cortical microtubules is observed in the anterior part of the differentiation zone. This is the origin of the crest-like body that appears at the end of spermiogenesis. The presence of striated roots associated with centrioles constitutes the first report of these structures in the spermiogenesis of a cyclophyllidean cestode.

Animals↗

PubMed1998

Subulura saloumensis n. sp. (Nematoda, Subuluroidea) from four species of rodents in Senegal.

A new species of the genus Subulura is described from 4 new rodent hosts: Arvicanthis niloticus, Mastomys erythroleucus, Mastomys huberti, and Tatera gambiana. Subulura saloumensis n. sp. differs from the congeneric species by the morphology of its head. the absence of buccal lobes, the length of right and left spicules, the absence of caudal alae, and the existence of a caudal papillae with a sensorial bristle. The latter, which we observe for the first time in specimens gathered from M. huberti, has never previously been described in a species of the genus Subulura.

Animals↗

PubMed1998

Putting evidence into practice.

A training module is described in which experienced health care managers from developing countries explore the challenges to be faced when attempting to use the results of systematic reviews of scientific studies on health care interventions in policy and practice.

Decision Making↗

PubMed1998

Ultrastructure of spermiogenesis and the spermatozoon of Anoplocephaloides dentata (Cestoda, Cyclophyllidea, Anoplocephalidae), an intestinal parasite of Arvicolidae rodents.

Spermiogenesis in Anoplocephaloides dentata begins with the formation of a differentiation zone delimited by a ring of arched membranes. This conical area shows 2 parallel centrioles with associated anterior reduced striated roots but without an intercentriolar body. Only 1 of the centrioles develops an axoneme that grows into a cytoplasmic extension. Two crestlike bodies appear when the nucleus initiates its migration along the spermatid body. We describe for the first time at the end of spermiogenesis the formation of an apical cone before the strangulation of the ring of arched membranes. The mature spermatozoon of A. dentata is filiform, tapered at both ends, and lacks mitochondria. Its anterior extremity has an apical cone measuring about 1,400 x 350 nm and 2 crestlike bodies. Cortical microtubules are spiralled at an angle of about 30 degrees to the spermatozoon axis. The axoneme, of the 9+1 pattern of Trepaxonemata (Polycladida, Seriata, "Typhloplanoida," "Dalyellioida," and Neodermata lacks a periaxonemal sheath and does not reach the extremities of the spermatozoon. Numerous granules of electron-dense material are observed in the posterior regions of each spermatozoon. Analysis of ultrastructural features found during spermiogenesis in A. dentata corroborates the presence of striated roots associated with the centrioles in cyclophyllidean species. Moreover, the presence of striated roots is described for the first time in type IV spermiogenesis.

Animals↗

PubMed1997

Ultrastructure of the spermatozoon of Dipylidium caninum (Cestoda, Cyclophyllidea, Dilepididae), an intestinal parasite of Canis familiaris.

We report for the first time the ultrastructure of the spermatozoon of a Dilepididae cestode. The mature spermatozoa of Dipylidium caninum is filiform and tapered at both ends and lacks mitochondria. The anterior extremity exhibits an apical cone of electron-dense material measuring about 600 nm in length and a single helicoidal crested-like body that is 150 nm thick. This single crested-like body is spiralized at an angle of about 40 degrees to the spermatozoon axis. The axoneme, showing the 9 + "l" pattern of the Platyhelminthes, lacks a periaxonemal sheath. The cortical microtubules constitute a continuous, submembranous, electron-dense material, and they are also twisted at an angle of about 40 degrees to the spermatozoon axis. Moreover, the nucleus is coiled in a helix around the axoneme, which is centrally located throughout its length. We demonstrate for the first time the presence of peripheral microtubules twisted to the spermatozoon axis up to the posterior extremity of the gamete.

Animals↗

PubMed1997

Comparison of human and murine isolates of Schistosoma mansoni from Richard-Toll, Senegal, by isoelectric focusing.

Studies on human and murine isolates of Schistosoma mansoni, from Richard-Toll, Senegal, were carried out by isoelectric focusing in polyacrylamide gels. Seven enzyme systems; lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G6PD), acid phosphatase (AcP), hexokinase (HK), glucose phosphate isomerase (GPI), and phosphoglucomutase (PGM), were used to compare the two isolates. All systems tested, apart from LDH, were found to be polymorphic for both isolates. Interestingly, one phenotype is more frequent than the remainder. The results show that there is no significant genetic variation between the S. mansoni isolates from man and the rodents, Arvicanthis niloticus and Mastomys huberti.

Acid Phosphatase↗

PubMed1997

Ultrastructure of spermiogenesis and the spermatozoon of Nomimoscolex sp. (Cestoda, Proteocephalidea) intestinal parasite of Clarotes laticeps (Fish, Teleost) in Senegal.

Spermiogenesis in Nomimoscolex sp. begins with the formation of a differentiation zone delimited at the front by arched membranes. It is bordered by cortical microtubules and contains two centrioles surmounted each by striated roots. The latter are linked together at their bases by a thin layer of electron-dense material. The two centrioles give each a flagellum that rotates and fuses with the median cytoplasmic extension. The nucleus elongates, becomes filiform and migrates between the axonemes in the cytoplasmic extension. During the nuclear migration, crested-like bodies form. After the migration of the nucleus, the old spermatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. The mature spermatozoon of Nomimoscolex sp. lacks mitochondria, is filiform and tapered at both its extremities. Its anterior end exhibits an apical cone of electron-dense material and three crested-like bodies of unequal length coiled in a spiral on its periphery. The axoneme is of the 9 + 1' pattern. The cortical microtubules are parallel to the spermatozoon axis. The nucleus is a fibrous cord of partly condensed chromatin. The cytoplasm is slightly dense but contains many electron-dense granules in regions II and III of the spermatozoon. Crested-like bodies and striated roots linked together by an electron-dense material have never been reported during the spermiogenesis in a proteocephalidean. In addition we describe for the first time the existence of three crested-like bodies in the Proteocephalidea.

Animals↗

PubMed1997

Gongylonema madeleinensis N. sp. (Nematoda:Spiruroidea), from Mastomys erythroleucus (Rodentia) from a Senegalese island.

A new species of gongylonematid parasites of the rodent Mastomys erythroleucus is described. Gongylonema madeleinensis n. sp. differs from the other species of the genus by the size of its eggs and spicules-gubernaculum complex, the form and distribution of its cuticular scutella, and the absence of a pore on its cephalic plate. After examination of the esophageal content of 270 continental and 29 insular rodents, G. madeleinensis n. sp. seems to be endemic to the island "des Madeleines" near Dakar, Senegal.

Animals↗

PubMed1996

Susceptibility of rodents to infection with Schistosoma mansoni in Richard-Toll (Senegal).

The susceptibility of Arvicanthis niloticus, Mastomys huberti, Mastomys erythroleucus and Mus musculus was studied to assess the capacity of these rodents to transmit Schistosoma mansoni. The susceptibility was determined by the percentage of adult schistosomes recovered, the number of eggs per gramme of faeces, the viability of these eggs and the capacity of the rodents to maintain the life cycle of Schistosoma mansoni. The percentages of adult worms recovered were respectively 18%, 11.5%, 8.4% and 20.5% in A. niloticus, M. huberti, M. erythroleucus and M. musculus. After infection, they liberate in the environment viable eggs whose miracidia are infectious for the intermediate host (Biomphalaria pfeifferi). The mean egg load was 300 +/- 327.8 in A. niloticus; 664 +/- 673.5 in M. huberti; 240 +/- 304.8 in M. erythroleucus; 400 +/- 361.5 in M. musculus.

Animals↗

PubMed1995

Microdialysis probes calibration: gradient and tissue dependent changes in no net flux and reverse dialysis methods.

Probe calibrations are required for accurate estimations of extracellular concentrations in microdialysis experiments. Several methods have been developed and validated for in vivo determination of dialysis membrane recovery such as the perfusion rate method and the No Net Flux method. In this study, the No Net Flux and the reverse dialysis methods were investigated. Both measure the net transport of drug across the dialysis membrane. The recovery was defined as R = (Cin - Cout)/Cin, where Cin and Cout were the concentrations of a compound in the perfusate and in the dialysate, respectively. First, the accuracy of the No Net Flux method to estimate in vivo recovery was compared in two situations: diffusion from the probe into the dialysis medium and diffusion from the outer medium into the probe. The point of no net transport was used to estimate the concentration surrounding the probe. Neither difference between extracellular concentrations (intercept values) nor difference between recoveries were observed. Then the reverse dialysis method was tested to estimate the relative loss of drug from the perfusate when the probe was placed in a drug-free medium. Finally comparisons of the behavior of the drug diffusion across the membrane under increasing gradient conditions have shown an asymptotic profile, specific of the tissue; blood, muscle, and adipose tissue. The faster a drug was removed by microvascular transport (blood > muscle > adipocytes), the higher was the recovery, until the perfusate concentration reached a threshold value where the transport process became gradient limited and no more tissue limited.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Scanning electron microscope examination of scale-like spines on the rostellumm of five Davaineinae (Cestoda, Cyclophyllidea).

The study by scanning electron microscope of the scolex of Cotugnia polyacantha, Raillietina (R.) echinobothrida, R (R.) tetragona, R. (R.) tunetensis and R. (Skrjabinia) cesticillus allowed us to demonstrate the presence, on the rostellum of each individual, of scale-like spines. We believe that these scale-like spines represent a new character of diagnosis for the whole of the Davaineidae.

Animals↗

PubMed1994

Ultrastructure of spermiogenesis and the spermatozoon of Aporina delafondi (Cyclophyllidea, Anoplocephalidae), intestinal parasite of turtle doves in Senegal.

Spermiogenesis in Aporina delafondi begins with the formation of a differentiation zone bordered by cortical microtubules and containing from the beginning a portion of nucleus and two parallel centrioles. One of the centrioles aborts, the other gives rise to a flagellum. The cortical microtubules elongate and spiralize while the nucleus migrates along the axoneme and crest-like bodies form at the level of the differentiation zone. The old spermatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. The mature spermatozoon lacks mitochondria, is filiform and tapered at both its extremities. Its anterior extremity is capped by an apical cone of electron-dense material and exhibits five crest-like bodies of unequal lengths on its periphery. Its cortical microtubules are regularly spiralized except at their posterior extremity where they become parallel to the spermatozoon axis. The cytoplasm is slightly dense in the anterior regions (I and II) and exhibits many protein granules and patches of electron-lucent material in the middle (III) and posterior zones (IV and V). The nucleus is an electron-dense cord coiled in a spiral around the middle region (III) of the axoneme. This is of the 9+ "1" pattern and ends before the posterior extremity of the gamete. Spermiogenesis in Aporina delafonidi differs from that of the other Cyclophyllidea by the very early movement of the nucleus into the differentiation zone, the formation of a ring of arched membranes in the distal part of the differentiation zone, the appearance of crest-like bodies during migration of the nucleus and the formation of a cytoplasmic bud which contains the abortive centriole and develops to temporarily form a large lateral extension. The mature spermatozoon differs from that of the other Cyclophyllidea in the presence of lucent patches in its cytoplasm and of five helicoidal crest-like bodies. The systematic position of the genus Aporina is also debated.

Animals↗

PubMed1994

Ultrastructure of spermiogenesis and the spermatozoon of Raillietina (Raillietina) tunetensis (Cyclophyllidea, Davaineidae), intestinal parasite of turtle doves in Senegal.

Spermiogenesis in Raillietina (Raillietina) tunetensis begins with the formation of a differentiation zone equipped with cortical microtubules and containing two centrioles. One of the centrioles very rapidly gives rise to a flagellum which fuses with a median cytoplasmic extension, the cortical microtubules elongate and arched membranes appear. After the migration of the nucleus two crest-like bodies form and the old spermatid becomes detached from the residual cytoplasm. The mature spermatozoon of R. (R.) tunetensis exhibits an apical cone of electron-dense material and two helicoidal crest-like bodies 100 to 200 nm thick. The cortical microtubules are spiralized and make an angle of about 60 degrees to the spermatozoon axis. The axoneme is of the 9 + "1" pattern and does not reach the posterior extremity of the gamete. The nucleus is a fine, compact cord wound in a spiral which may make as much as two complete coils round the axoneme. The cytoplasm is electron-dense in region V of the spermatozoon. Over the rest of the gamete it is made up of lucent material divided into irregular compartments by electron-dense material. The latter consists of a fine, discontinuous peri-axonemal sheath, a fine granular sub-microtubular layer situated in regions I and II, and irregularly spaced partitions localized in regions III and IV. A nucleus with an annular cross section has never been described in a cestode spermatozoon; nor have two crest-like bodies of different length and thickness. In addition we report for the first time the existence of crest-like bodies in the Davaineidae.

Animals↗

PubMed1994

[Ultrastructural similarity of spermatozoa of some Cyclophyllidea].

The mature spermatozoa of Cotugnia polyacantha, Raillietina (R) tunetensis, Inermicapsifer madagascariensis and Avitellina centripunctata have an almost identical ultrastructural organization. They are tapered at both extremities. Their anterior extremity exhibits an apical cone of electron dense material and one or two helicoidal crested-like bodies. Their cortical microtubules are spiralized and are seen, in longitudinal and cross sections, as continuous, dense, submembranous material. Their nucleus is a cord of dense chromatin, coiled in a spiral around the 9 + "1" pattern axoneme. The cytoplasm is moderately dense to electron lucent and exhibits irregularly spaced walls of proteinaceous material and a fine periaxonemal sheath of dense material. In this work we show that the Anoplocephalidae are close to the Davaineidae by the characters of the spermatozoon and that Inermicapsifer should be put back among the Davaineidae, according to the opinion of Joyeux & Baer (1961) and come into conflict with other works more particularly Schmidt (1986).

Animals↗

PubMed1993

Diversity and specificity in cestodes of the genus Moniezia: genetic evidence.

Electrophoretic study of two species of Moniezia cestodes, M. expansa and M. benedeni, sampled in African (Senegal) domesticated ruminants, revealed a complex of species and a degree of specificity more pronounced than that previously described. The status of the different species is validated by the probable occurrence of within species cross-mating. A European origin is suggested for M. expansa due to identical isoenzyme patterns in cestodes from France, whereas some atypical individuals may be derived from wild African ruminants.

Animals↗

PubMed1993

[AIDS and non Hodgkin's malignant lymphoma disclosed by massive hematemesis].

A 40-year-old man was admitted for a major haemorrhage from the upper gastro-intestinal tract. An emergency gastrectomy was performed to control the bleeding. The histopathological study revealed a non-Hodgkinian lymphoma associated with an AIDS, which had remained unknown. The postoperative period was complicated by several infections. The patient died 2 1/2 months after the hematemesis. Such major haemorrhage from the upper gastro-intestinal tract as the presenting symptom of AIDS is very rare, although this has been described during the course of the disease. This case illustrates the importance in reminding operating theater staff (anaesthetists, surgeons, nurses) of the risk of viral contamination when treating a young patient with hematemesis and the necessity of wearing gloves, face masks and glasses.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Reinvestigation of the ultrastructure of spermiogenesis and the spermatozoon of Hymenolepis nana (Cestoda, Cyclophyllidea), parasite of the small intestine of Rattus rattus.

Spermiogenesis in Hymenolepsis nana begins with the formation of a differentiation zone. This is limited at the front by arched membranes, is surrounded by cortical microtubules associated with 12 crested-like bodies, and contains a single centriole made up of doublets. The distal centriole gives rise to a flagellum that grows at the same pace as the cortical microtubules. Migration of the nucleus takes place after the formation of the flagellum. It is followed by the separation of the old spermatid from the residual cytoplasm. The mature H. nana spermatozoon is filiform and lacks mitochondria. The axoneme, of the 9 + "1" pattern of the Platyhelminthes, does not reach the extremities of the spermatozoon. The nucleus is electron dense and is in close contact with the axoneme around which it coils in a spiral making an angle of 10 degrees to 15 degrees with the spermatozoon axis. The cortical microtubules follow a 10 degrees to 15 degrees helicoidal path along almost their whole length, except at their posterior extremity, where they are parallel to the spermatozoon axis. H. nana is distinguished by the early development of 12 crested-like bodies of different lengths and by the existence of a single centriole in the differentiation zone. Such a high number of crested-like bodies had never previously been reported in a cestode.

Animals↗

PubMed1992

Synthesis and ACE inhibitory activity of the stereoisomers of perindopril (S 9490) and perindoprilate (S 9780).

Perindopril, a powerful ACE inhibitor contains 5 chiral carbons, thus there is the possibility of 2(5) = 32 stereoisomers for the general structure 1. These 32 stereoisomers were synthesized by cross-coupling the 8 stereoisomers of perhydroindole 2-carboxylic acid benzylester with the 4 stereoisomers of 2-(1-carbethoxybutylamino) propionic acid 4, then hydrogenating the resulting benzylesters. Each stereoisomer of perindopril furnished by saponification the corresponding diacid stereoisomer 2 of perindoprilate which is the active form of perindopril. For each of the 32 stereoisomers 2 the in vitro ACE inhibitory potency (IC50) was determined. Four of them, including perindoprilate, had activities in the nanomolar range, and four more were ca. 10 x less active. The four acid esters 1 corresponding respectively to the four most active diacids 2 in vitro were studied (1 mg/kg via the oral route) for their in vivo activity in dogs. It could be concluded that p.o. absorption of the active acid esters 1 and their activation to the active diacid 2 depended only on the chiralities of the two ring junction carbons of the perhydroindole ring.

Administration, Oral↗