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Biomedical subjects

G Petit

Publications and source records attributed to G Petit.

At least 55 records · Page 3Linked to original sources
PubMed1986

[A filaria of African Muridae in the wall of the colon: Monanema martini n. sp].

Description of M. martini n. sp. (= M. nilotica El Bihari et al., 1977 sensu Bain et coll., 1985), a parasite of Arvicanthis niloticus from Mali. The natural host is Arvicanthis niloticus from Mali; the description is based on material from experimentally infected laboratory-bred rodents (holotype from A. niloticus; other specimens from Lemniscomys striatus). Like other related species the microfilariae of M. martini are said to be "skin dwelling" (in fact they are in cutaneous lymphatic vessels). The main characteristic feature of this new species is the localization of the adults in the lymphatic vessels of the colon.

Animals↗
PubMed1985

[2 new filariae of a monkey, Saimiri sciureus, in Guyana].

Description of two new Filariae, parasites of Saimiri sciureus L. (Georgetown type, karyotype 14/7) from Guyana. Dipetalonema robini n. sp., fourth species of the genus, is frequent and associated with the morphologically similar species, D. gracile (Rud., 1809); D. robini differs from D. gracile by structure of caudal lappets of female, vagina, microfilaria and area rugosa. The second filaria, also frequent, belongs to the subgenus Tetrapetalonema which contains a dozen species; Mansonella (T.) mariae n. sp. is similar to M. (T.) marmosetae Faust, 1935 and M. (T.) tamarinae Dunn & Lambrecht, 1963 but is distinguished by the position of the head papillae, the cuticular ornamentation of the body and the microfilaria.

Animals↗
PubMed1985

[Experimental transmission of Monanema nilotica El Bihari & coll., 1977, a filaria with skin-dwelling microfilaria parasitic in African murids].

The value of Monanema of murids as experimental models of ocular lesions due to onchocerciasis would be greatly increased if we could experiment with several host and parasite species since, in many cases, the lesions induced are more significant when the host-parasite association is poorly adapted. The life cycle of 2 isolates of Monanema nilotica is completed, one from Lemniscomys striatus from the Central african Republique and the other from Arvicanthis niloticus of Mali. As in M. globulosa, infective larvae develop in Ixodidae (Rhipicephalus sanguineus and Hyalomma truncatum); 20 to 30 larvae inoculated into the murids suffice for a patent infection.

Africa↗
PubMed1985

[New data on the transmission of filariae].

This paper summarizes research of the past several years on two phases of filarial transmission: the ingestion of microfilariae by the vector and the regulation of the percentage of successful parasites by the vector. Experiments involved several different models for study: injection of inert particles into the bloodstream of a rodent and their subsequent ingestion by a vector; ingestion of gametocytes of different ages by vectors of a rodent malaria; and a monkey simultaneously infected with four different species of filariae. This has led to the idea that there exist two categories of microfilariae: those blood-borne microfilariae which cannot enter capillaries and those microfilariae which are said to be "dermic" but in fact live trapped in capillaries and are only taken up through the suction applied by vectors during their feeding. Thus, the lesions of onchocerciasis are caused by microfilariae accidentally leaving the capillaries and entering the surrounding tissues. Passage through the stomach wall of a vector by microfilariae is the essential stage in regulating the percentage of successful parasites: the phenomena of facilitation or limitation. Two examples of limitation are given. In the model--Onchocerca volvulus-Simulium sirbanum--the thickness of the peritrophic membrane which traps microfilariae is determined by the number of microfilariae ingested; the greater the number ingested the thicker is the membrane. In the model--Molinema dessetae-Aedes aegypti--the lytic reactions of individual digestive cells which are provoked by attacking microfilariae occur only in heavily infected mosquitoes. The "immunity" of the arthropod vector seems to take a number of forms which are distinctly different from those of vertebrates.

Animals↗
PubMed1985

[Comparative study of the cutaneous and ocular lesions of murids Lemniscomys striatus parasitized by Monanema spp. and Atherurus africanus parasitized by Cercopithifilaria sp. with those of human onchocercosis].

Histologic examination of skin and ocular lesions in various rodents infested by various species of Filariae with skin-dwelling microfilariae disclosed very similar aspects as compared to lesions noted in human onchocerciasis: coexistence in the same organ of five following types of lesion: vascular changes; subacute inflammatory cells infiltration; granulomatous lesions; scarring alterations; vascular ectasia.

Animals↗
PubMed1985

[Filariae of rodents useful for the experimental study of human onchocerciasis].

In order to obtain skin and ocular lesions comparable to those which are found in human onchocerciasis, it is not necessary to use members of the genus Onchocerca which are found in large animals and difficult to use. Other Filariae with biological features comparable to Onchocerca volvulus can be used in which microfilariae are localized in capillaries and can escape from the walls and produce lesions similar to those in onchocerciasis. The life cycles of several filariae of rodents have been worked out and they are proposed as experimental models as the tick vectors and the rodent hosts are easily maintained in the laboratory.

Animal Population Groups↗
PubMed1983

[Studies on Plasmodium atheruri].

Plasmodium atheruri, a parasite of the African porcupine Atherurus africanus, is infective to splenectomised laboratory Rats and Mice, to Hamsters and to 2 exotic rodents which are easily bred in captivity: Calomys callosus and Meriones unguiculatus. Sporogony develops in Anopheles stephensi fed on Atherurus and on laboratory rodents; it is similar to that of the Rodent Plasmodia. Exoerythrocytic schizogony usually lasts 4 to 6 days but schizonts have been found in the liver of a porcupine at day 8. Schizogony in the blood (induced by inoculation of infected blood or by injections of sporozoites) follows two stages which are morphologically distinct: a) acute infections developing in clean Atherurus, following splenectomy of infected Atherurus or in laboratory rodents; it is characterized by large trophozoïtes, schizonts with 8 to 16 merozoites, gametocytes and infectivity to Anopheles. b) chronic infection which only occurs in the blood of Atherurus and follows the acute stage 15 to 21 days after its onset; it is characterized by small trophozoites and schizonts producing 4 merozoites. Thus it is thought that the chronic stage only occurs in the natural host when it is immunized. We think that, in nature, chronic schizogony maintains the parasitaemia through periods of low transmission and is followed by "recrudescences". The mechanisms that trigger the "recrudescences" are unknown but are probably connected with a decrease in the immune status of the host.

Animals↗
PubMed1983

[Castleman's pseudotumor. Apropos of a case with pelvic localization].

The authors report a case of a pelvic site of a Castleman pseudo-tumour, still called angio-follicular hyperplasia or lympho-vascular hamartoma. This disorder of unknown aetiology may be situated anywhere along the lymphatic chains (70% of cases in the mediastinum). It is often associated with immuno-haematological disorders. Suitable for surgical treatment, the course is always favourable.

Adult↗
PubMed1982

[Intake of microfilariae by the vector in the case of a low microfilareamia (author's transl)].

The study of the intake of microfilariae of Dipetalonema dessetae by Aedes aegypti leads to two conclusions with respect to the microfilaraemia: --there is no concentration of microfilariae in the uptake of blood by Aedes. --the microfilariae are nearly homogeneously distributed in the vertebrate host blood available to the vector for feeding. Such a distribution of microfilariae in the cutaneous blood supply of the host gives the maximum chance for a mosquito to become infected when taking a blood meal. In the pair Wuchereria bancrofti--Aedes polynesiensis the capacity of individuals with a low microfilaraemia to transmit infections seems to be related to a limitation phenomenon.

Aedes↗
PubMed1981

[R1 cell and musculature of Filariae; ultrastructural analysis (author's transl)].

Ultrastructural study of ontogenesis of a filaria, Dipetalonema (M.) dessetea, confirms Bain's (1970) hypothesis, following which the R1 cell plays a role in the elaboration of the musculature of the adult filaria. Anatomical observations related to the hypodermis and musculature of the larva (distribution of the cells, nature of their junctions, presence of intermediate cells between embryonic cells derived from R1 cell and muscle cells) show that the cells derived from R1, which form four longitudinal files, produced successively, from 5th to 13th day, about ten files of muscle cells in each submedian field. The primary musculature of the microfilaria, which corresponds to a single file of muscular cells in each field, is not ectodermic, as supposed before, but mesenchimatic. At the vicinity of R1 daughter cells, this musculature is slightly dedifferenciated (about 5 files of myofilaments instead of 10-20 in the microfilaria and the L3); then its evolution becomes identical to this of new formed muscle cells. The presence as well as the evolution of the R1 cell seem to be identical in every totally heteroxenous Phasmidian Nematodes; both suggest analogy with the imaginal discs of the holometabolic Insects.

Animals↗
PubMed1981

[Intake of microfilariae by the vector for a periodic filarioid, Dipetalonema dessetae (author's transl)].

The Filariid D. dessetae in its natural host, Proechimys oris, has a daily periodic microfilaraemia with a conspicuous peak during the day (blood from the ocular sinus). --If the mosquitoes engorge during the daily peak, the density of microfilariae ingested is equal or slightly superior to the density of microfilaria in the blood from the ocular sinus. However, if they engorge during the night they ingest 2,5 times the number of microfilariae than the density of microfilariae in the ocular sinus indicates they should. Thus during the night there is a phenomenon of persistence of microfilariae in the cutaneous blood circulation of the rodent. --With mosquitoes of similar size each ingesting a similar volume of blood the distribution of Aedes as a function of the number of microfilariae ingested resembles the Poisson distribution. This indicates that the distribution of microfilariae which are accessible to the vector in the blood of Proechimys is nearly homogeneous.

Aedes↗
PubMed1981

[On the Filariae of the genus Aproctella (Splendidofilariinae) (author's transl)].

Aproctella alessandroi n. sp., parasitic in various Passeriformes in Colombia and Guadeloupe, and A. golvani n. sp., a similar species with smaller microfilariae parasitic in sparrows in Guadeloupe, are described. The life cycle of A. alessandroi was studied in Aedes togoi (development in 13 days in the flight muscles; first-stage larva cylindrical; third-stage larva 1 330-1 600 microns long; oesophago-intestinal junction distinct). The larval biology of Aproctella is very similar to that of Cardiofilaria, confirming the close relationship of these two genera. The biology differs from that of two other genera of Splendidofilariinae of birds, Splendidofilaria and Chandlerella (vectors: Culicoides and Simuliids; development in flight muscles and haemocoel; first stage larva almond-shaped; third stage larva 400-600 microns de long; oesophago-intestinal junction indistinct). In these latter genera, the larval biology is remarkably similar to that of Lemdaninae of reptiles and birds (Saurositus, Eufilaria). It seems there is not a distinct separation between the Splendidofilariinae and the Lemdaninae.

Animals↗
PubMed1981

[A new filaria of a squirrel in Thailand, Breinlis (B.) manningi n. sp., and its development in Aedes (author's transl)].

B. (B.) manningi, a parasite of Menetes berdmorei (Sciurinae) in Thailand, is very close to B. (B.) sergenti from an Asian Lemur. As in the other Breinlia, the larva develops in adipose tissue of mosquitoes (Aedes) and the infective form, a little longer than 1 mm, has a proportionnally very long tail (75-92 micron), ended by a conical tip and two lateral salient more or less conical processes.

Aedes↗
PubMed1978

[The electrocardiogram during bilharziosis caused by Schistosoma mansoni].

The electrocardiographic abnormalities associated with bilharziasis are not well-known. This study, carried out in Guadeloupe, involved 220 cases of both sexes with bilharziasis, and 157 control subjects. The changes on the electrocardiogram were: an ST elevation of 0.1 to 0.5 mV associated with a large T wave in the intermediate and left precordial leads (16.8%), flattening of the T wave (13%) in V1 to V3 and beyond, a negative T wave (10.8% in the right precordial leads V1, V2, V3, and left ventricular hypertrophy (10%). The abnormalities which were found were identical to those described in the "normal" black person, and led us to discuss whether there was really a characteristic ECG for the black races. Additionally we were able to conclude that these abnormalities were unrelated to anaemia or to therapy against bilharziasis, and that there was no abnormal sex distribution. Moreover this study has revealed that the population of Guadeloupe who have no parasitic infection have ECG abnormalities (4.8%) more commonly than the white races, and has led us to suspect the possibilities of as yet underfined abnormalities which cannot be regarded as "normal".

Adolescent↗