[Action of venoms on blood coagulation: diagnosis of hemorrhagic syndromes]. / Action des venins sur la coagulation sanguine: diagnostic des syndromes hémorragiques.

Venoms from Viperidae, Crotalidae, some Australian Elapidae and few Colubridae are a mixture of enzymes which impact on blood coagulation in several ways. These proteins can be classified as haemorragins which induce disorders of the capillary permeability, disintegrins and related proteins which disturb the clotting time while acting on plate adhesion, and proteases which cleave peptides. Venoms contain molecules directed against several targets of the coagulation system. The same molecule may present different activities. Components of snake venoms are used in diagnostic coagulation tests, fundamental research and as drugs against infectious agents, cancer or haematological disorders. The structural differences between proteins from snake venoms and natural coagulation factors and the target diversity of the venom components explain why it remains illusory to treat bleedings when acting just at symptom level. Conversely, antivenom, whose components are directed against the venom proteins, is the only aetiological therapy effective against snake envenomations.

Roles of FMO and CYP450 in the metabolism in human liver microsomes of S-methyl-N,N-diethyldithiocarbamate, a disulfiram metabolite.

BACKGROUND: The conversion of S-methyl-N,N-diethyldithiocarbamate (MeDDC) to MeDDC sulfine is the first step after methylation in the metabolic pathway of disulfiram, an alcohol deterrent, to its ultimate active metabolite. Various isoforms of CYP450 have recently been shown to catalyze this reaction, but the involvement of flavin monooxygenase (FMO) in this metabolism in humans has not been evaluated. In this study we examined the ability of recombinant human FMO3 in insect microsomes to metabolize MeDDC, and investigated the relative roles of FMO and CYP450 in the metabolism of MeDDC in human liver microsomes. METHODS: HPLC-mass spectrometry was used to identify the products of MeDDC formed by human liver microsomes and by recombinant human FMO3. MeDDC metabolism in human liver microsomes was studied by using either heat inactivation to inhibit FMO, or N-benzylimidazole (NBI) or antibodies to the CYP450 NADPH reductase to inhibit CYP450. RESULTS: We confirmed by HPLC-mass spectrometry that MeDDC sulfine was the major product of MeDDC formed by human liver microsomes and by FMO3. Recombinant FMO3 was an efficient catalyst for the formation of MeDDC sulfine (5.3+/-0.2 nmol/min/mg, mean+/-SEM, n = 6). Inhibition studies showed MeDDC was metabolized primarily by CYP450 in human liver microsomes at pH 7.4, with a 10% contribution from FMO (total microsomal activity 3.1+/-0.2, n = 17). In the course of this work, methyl p-tolyl sulfide (MTS), sulfoxidation of which is used by some investigators as a specific probe for FMO activity, was found to be a substrate for both FMO and CYP450 in human liver microsomes. CONCLUSIONS: Our results prove that MeDDC sulfine is the major product of MeDDC oxidation in human liver microsomes, MeDDC is a good substrate for human FMO3, and MeDDC is metabolized in human liver microsomes primarily by CYP450. We also showed that use of MTS sulfoxidation as an indicator of FMO activity in microsomes is valid only in the presence of a CYP450 inhibitor, such as NBI.

[Malaria in children at the Sihanoukville Hospital (Cambodia)]. / Paludisme de l'enfant à l'hôpital de Sihanoukville (Cambodge).

The authors have studied 68 children admitted with malaria in Sihanoukville Hospital (Cambodia) from December 1992 to April 1993. Sihanoukville is located on coast of the country, in a hypoendemic area with seasonal transmission occurring during this study. The patients lived in urban (1/3) or in rural areas (2/3). Plasmodium (P.) vivax alone was found in 15 cases. Among them, two patients presented with severe malaria, but chloroquine was efficient in all cases. P. falciparum with or without P. vivax, was predominant (53 cases). Most of these cases were severe, according to WHO criteria (n = 43), from which 11 deaths occurred (25%). There were 26 cases of cerebral malaria, with a death rate of 34.6%. A severe course was observed with the following criteria: prostration or coma (p = 0.029), severe anaemia (p = 0.037) and hyperparasitaemia (p = 0.00078). A significant longer delay for treatment and admission was noted among rural patients (p = 0.023 and p = 0.011 respectively). In those children, hyperparasitaemia, poor clinical status on admission and lethality were more frequent. The clinical course was not clearly improved with the addition of erythromycin in the quinine regimen. No quinine resistance was observed in this data.

[Hyperbaric oxygen therapy in cerebral circulatory insufficiency]. / L'oxygénothérapie hyperbare dans les insuffisances circulatoires cérébrales

From a study bearing upon 26 patients suffering from a cerebral circulatory insufficiency induced by a stenosis or a thrombosis, the writers analyse the part played by Hyperbare Oxygen in the neurologic evolution. The defining of the efficacy criteria enabled them to determine whenever this part was prevalent and obvious (that's to say in 20 p. 100 of the cases). However, in the other cases it was hard to decide whether Hyperbare Oxygen played any part. Only functional lesions are liable to benefit from this therapy which seems mainly useful to cover the period of circulatory adaptation at a time when supply circulations may come into play. The difficulty to appreciate the importance of supply circulations urges on to treat this type of patients early enough in a systematic way and all the more so as they are young.