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F Peyron

Publications and source records attributed to F Peyron.

120 records · Page 7Linked to original sources
PubMed1989

Plasmodium falciparum growth inhibition by human platelets in vitro.

Platelets take an active part in immunological processes as well as in haemostasis, especially in the host-parasite relationship. Our aim is to assess the growth of Plasmodium falciparum, cultured in human erythrocytes in the presence of fresh washed human platelets, since thrombocytopaenia is frequently observed during malarial infections. Our results show that platelets induce a dose-related growth inhibition of P. falciparum. Both proliferation and maturation of intraerythrocytic stages of the parasite are inhibited. This growth inhibition is triggered by the parasite itself as neither specific antibodies nor any other components are needed to activate platelets. Activated platelets are directly toxic since complement is not involved. Furthermore, inhibition is not mediated by erythrocyte lysis or by toxic oxygen metabolites. Platelets induce an inhibition of P. falciparum growth, at least in vitro, although the importance of their role played in vivo in malarial immunity has yet to be evaluated.

Animals↗
PubMed1989

[Lymphocyte subpopulations during a longitudinal survey in an endemic malaria zone].

In a longitudinal survey conducted in savanna area (Burkina Faso, West Africa) where malarial transmission is seasonal, we studied modifications of T, B lymphocytes, NK cells, and CD4+, CD8+ and activated T subpopulations of 61 patients (31 adults and 30 children, among them 20 showed at least one malarial attack during the survey). Analysis was made by direct immunofluorescence on a cytofluorimeter. Our study did not show any significant differences in lymphocytes subpopulations according to age or presence of malarial attack. None of the lymphocyte markers in the peripheral blood are related to premunition, may be because host/parasite conflict mainly occurs in deep organs.

Adolescent↗
PubMed1985

[Praziquantel in the treatment of opisthorchiasis in Southeast Asian refugees. Evaluation of 153 cases].

153 patients coming to France from Southeast Asia were treated with Praziquantel for Opisthorchiasis. All these patients, 52 children and 101 adults were examined 30 to 90 day after arrival in France. They came from Laos (118 cases), Vietnam (10 cases) and Cambodia (25 cases), generally via Thailand. 7 heavy (10.000-29.999 Eggs Per Gram of faeces, EPG), 55 moderate (1.000-9.999 EPG) and 91 light infections (1-999 EPG) were detected. Praziquantel was given at a dose of 25 mg/kg body weight, orally, three times on a single day at intervals of 4-6 hours. Clinical tolerability was perfect in 59 patients and pretty good in the 94 remaining cases. We only observed, for one or two days, lassitude, headache, drowsiness, nausea, epigastric pain or arthralgia-myalgia, always of weak or moderate intensity and for 1 or 2 days. The biological tolerability was excellent without any variation of the biological norm values (47 parameters). The therapeutic efficacy was remarkable with 100% cure in all patients, who were followed-up for 40 days. All earlier controls (7th, 20th days) were always negative except for two patients who were completely negative on day 40th and later.

Adolescent↗
PubMed1984

Therapeutic results in opisthorchiasis with praziquantel in a reinfection-free environment in France.

108 patients coming to France from Southeast Asia were treated with praziquantel (2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a] isoquinolin-4-one, EMBAY 8440, Biltricide) for opisthorchiasis. All patients, 31 children and 77 adults, were examined at the Department of Parasitic Diseases 30 to 90 days after arrival in France. They came from Laos (79 cases), Viet Nam (4 cases) and Cambodia (25 cases), generally via Thailand. 6 heavy (10 000-19 999 eggs per gram of faeces, EPG), 23 moderate (1000-9999 EPG) and 79 light infections (1-999 EPG) were detected. Praziquantel was given at a dose of 25 mg/kg body weight, three times on a single day at intervals of 4 h. The biological tolerability was excellent without any variation of the biological norm values (47 parameters). Clinical tolerability was perfect in 48 patients and pretty good in the 60 remaining cases. We only observed, for one or two days, lassitude, headache, drowsiness, nausea, epigastric pain or arthralgia-myalgia always of weak or moderate intensity. The therapeutic efficacy is remarkable with 100% cure in all patients who were followed-up for 90 days. All earlier controls (7th, 20th, 40th days) were always negative except for one child with a light infection still weakly positive at the 7th, 20th and 40th day controls but negative, too, after 90 days.

Adult↗
PubMedDate not supplied

Serological reactivity to the ring-infected erythrocyte surface antigen and circumsporozoite protein in gravid and nulligravid women infected with Plasmodium falciparum.

To investigate potential mechanisms for pregnancy-associated alterations in the immune response to malaria, we tested plasma samples from Plasmodium falciparum-infected nulligravida (42), primigravida (23) and multigravida (38) Kenyan women for reactivity to the ring-infected erythrocyte surface antigen (RESA) by a modified indirect fluorescent antibody assay and to synthetic peptides derived from amino acid sequences of RESA and the circumsporozoite (CS) protein of P. falciparum by an enzyme-linked immunosorbent assay. Reactivity to RESA showed the lowest titres in primigravid women, intermediate titres in nulligravid women and the highest titres in multigravid women (loge mean antibody = 3.28, 4.64, and 5.28, respectively, P less than 0.03), but was not associated with initial parasite density or response to chloroquine treatment. No relationship in antibody reactivity to the 3 synthetic peptides of the RESA molecule was observed by gravidity (0, 1, or greater than or equal to 2), age, initial parasite density or response to treatment. Levels of antibody to the synthetic peptides of the CS protein increased with age and were higher in gravid than in nulligravid women in the 15-19 year age group. The increased malaria prevalence and parasite density and the decreased response to antimalarial treatment in pregnant women is not explained by lower levels of antibody to RESA or CS protein during pregnancy.

Adolescent↗
PubMedDate not supplied

Protective role of platelets in chronic (Balb/C) and acute (CBA/J) Plasmodium berghei murine malaria.

The role of blood platelets in the pathogenesis of malaria remains unclear. In this study we investigated the role of experimentally caused thrombocytopaenia in chronic (Balb/C) and acute (CBA/J) Plasmodium-berghei-induced murine malaria. A group of 30 Balb/C mice were rendered thrombocytopaenic by injection of anti-mouse platelet serum given every 2 days from day 2 to day 8 after malaria infection. Compared with the control group, thrombocytopaenic mice showed a greater mortality. The Kaplan-Meier estimate of the risk of death was 4.37-fold higher in the thrombocytopaenic group. Parasitaemia and weight loss was in agreement with the protective effect of platelets. In the acute malaria model, the survival rate was less significant but the estimated risk of death was 1.7-fold higher in the treated group. These results suggesting a protective role of platelets in murine malaria are not in line with previous reports of the literature. Taken together our data suggest, however, that platelets, similarly to some inflammatory cytokines like TNF, play a dual role in the pathogenesis of malaria. Depending on experimental conditions, e.g. the time of onset of thrombocytopaenia, the beneficial role of platelets may outweigh the deleterious one.

Acute Disease↗
PubMedDate not supplied

[Malaria: chloroquine resistance].

Chloroquine remains the most commonly antimalaric drug utilized all around the world (340 t in 1988). Its efficiency is linked to its action on the digestive vacuole of plasmodium. Since 1957, the areas of resistance are spreading over of an alarming way, striking all continents. 3,000 cases of malaria are imported in France each year, and 90% of the strains tested in vitro by incorporating tritium hypoxanthine are resistant to chloroquine. The resistant parasites are able to exclude chloroquine from their cytoplasm and produce in great number two genes to synthetize a glycoprotein, probable agent of cellular exclusion of the antimalaric drug. Despite of it, to prescribe chloroquine in prophylaxis remains indispensable, because the risk of severe malaria due to some sensitive strains of Plasmodium falciparum.

Adolescent↗
PubMedDate not supplied

[Focus on Schistosoma intercalatum].

Area of frequent occurrence of Schistosoma intercalatum is limited to few countries along the Guinea Gulf although the main intervening agents, Bulinus globosus, Bulinus forskalii are dispersed all over Africa. Reservoir of Schistosoma intercalatum is only human and its cycle is difficult to keep up in test animals. Clinical manifestations are, the most often, a simultaneous inflammation of the rectum and sigmoid. Diagnosis is based on the presence of ova with terminal spine in feces or in biopsies of rectal mucosae. Serology, not specific of this species, eases finding of low infestations. Treatment is based on Praziquantel.

Africa, Central↗
PubMedDate not supplied

[Immunization against human malaria: present knowledge].

The authors review different aspects of immunization against malaria according to the different stages of the parasitic cycle of Plasmodium falciparum: sporozoite vaccine preventing organism infestation, merozoïte vaccine and gametocyte vaccines preventing the accomplishment of the sexual cycle. Progress of molecular biology and better knowledge of cellular immunity provide some prospects regarding parasitic vaccinology, thanks to genetic engineering. Recombinant vaccines in vitro, in vivo and synthetized are under study and provide the best prospects regarding immunization against human malaria.

Animals↗
PubMedDate not supplied

Plasma levels of TNF-alpha soluble receptors correlate with outcome in human falciparum malaria.

Plasma from immune (residents of malaria infested areas) and non immune (European travellers) patients suffering from cerebral malaria, severe or mild, was analyzed for the presence of soluble tumor necrosis factor receptors. On admission of the subjects, sTNF-R55 and sTNF-R75 levels were significantly elevated in all groups and correlated with TNF-alpha. Except for sTNF-R55 whose levels were higher in severe than in mild malaria, no correlation was observed between soluble receptors and clinical status. Nevertheless, sTNF-R55 and sTNF-R75 were significantly more elevated in patients who died (10.7 +/- 2.3 ng/ml and 94.9 +/- 31 ng/ml, respectively) than in those surviving (5.5 +/- 0.4 ng/ml and 37.4 +/- 5.4 ng/ml respectively). A marked correlation was observed between soluble receptors levels and some biological markers of gravity like creatinine, urea, and bilirubin. In 13 non immune patients, circulating soluble receptors levels decreased significantly after 7 days when clinical and biological malaria features had disappeared, but TNFsR75 remained above normal levels. After a fortnight of treatment in 17 immune patients, sTNF-R55 and sTNF-R75 remained elevated. However, the ratios of TNF-alpha/s TNF-R55 and 75 were not higher in the cases of cerebral malaria or fatal outcome. Further studies are required to determine if elevated levels of sTNF-R55 and sTNF-R75 are beneficial, due to the inhibition of TNF-alpha or whether they are detrimental since they stabilize this deleterious cytokine.

Adolescent↗