[Contribution of the laboratory to the evaluation of brain-dead patients for obtaining organs from dead individuals]. / Apport du laboratoire dans l'évaluation des patients en mort encéphalique en vue d'un prélèvement d'organes sur la personne décédée.

The removal organ in order to transplantation is realized often for patient deceased. It was regulation activity that passes in urgency context where laboratory play an important role. The biochemistry, immunology, haematology, toxicology and microbiology analysis allows the validation of the donors, the supervision of the functional quality of organ and the definition of the best couple donor-recipient.

[Direct determination or estimated value of plasma ionized calcium : indications and limits]. / Dosage direct du calcium ionisé plasmatique ou estimation par calcul: intérêts et limites.

Calcium plays a fundamental role in many essential for life functions. Ionized calcium (Ca(++) ) represents free fraction and 50% of the total calcium in the plasma is accepted as its physiologically active form. On almost all laboratories, only total calcium is routinely measured, and ionized calcium concentration is calculated based on calcium, protein or albumin concentrations for many plasma sample or with others parameters like pH. Since 1935, the literature was abounted with "correction" formulae of varying degree of sophistication. Many laboratories routinely use correction formulae to either calculate an "adjusted" or "corrected" total calcium, or "ionized" fraction is calculated,but these determinations lack of accuracy or precision. Errors associated with the measurement of the other variables contribuate to the difficulty in producing a useful correction formulae. Direct measurement of ionized calcium by potentiometry is the method of choice for this assay. Improvements in ion selective electrodes (ISE) technology make possible the routine clinical measurement of Ca(++). However this technology implies several obligations for its use, particulary in blood ampling, storage and transport. In this review, characteristics of different available analysers are described. We think that Ca(++) should be systematically performed and not calculated in pathological situations where an possible alteration of the calcium metabolism is found especially in multiple myeloma in which paraprotein may bind calcium.

Physico-chemical and pharmacological comparison of pyridoxylated hemoglobin bound to polyoxyethylene or polymerized by glutaraldehyde.

Two modified hemoglobin solutions were assessed using the same physico-chemical and pharmacological techniques. The first was prepared by covalent binding of monomethoxypolyoxyethylene (MPOE) 1.9 kDa to pyridoxylated hemoglobin (PLP-Hb). The resulting conjugate had a molecular size of 100 kDa (MPOE-PLP-Hb). The solution was cleared of non-fixed MPOE through ion exchange chromatography on Spherodex, thus bringing viscosity and oncotic pressure back to physiological values. The second was prepared by limited polymerization of pyridoxylated hemoglobin with glutaraldehyde (POLY-PLP-Hb). Tangential flow ultrafiltration achieved a satisfactory polymer/oligomer return. Quality controls showed no difference between the solutions. Total isovolemic exsanguinotransfusions in the rat did not help differentiate the two solutions. Hemorrhagic shock (80% of blood volume, rat) gave definitive survival for 8 of the 14 animals tested with MPOE-PLP-Hb (57%) but only 3 of the 8 animals tested with POLY-PLP-Hb (38%). None of the chemical approaches to reduce hemoglobin loss proved any more efficient than another, with the evaluation techniques employed.

Pyridoxylated polymerized hemoglobin solution processing. Interest of a membrane molecular fractionation step.

Glutaraldehyde hemoglobin polymerization gives too many high polymers, resulting in a too viscous solution. We describe here an alternate method leading to superior results, as compared to the classical one. This method includes a molecular fractionation step using a tangential flow ultrafiltration that secondarily lowers the unpolymerized tetramer's content of a mildly polymerized, pyridoxylated hemoglobin solution (Pyr-Poly Hb). This leads to an adequately polymerized product with a lesser high polymer content, implying a lower viscosity. We thus obtain a pyridoxylated, polymerized molecular fractionated solution presenting suitable features as a blood substitute: A 7.5 g% hemoglobin 2 g% albumin solution had a 16% unpolymerized tetramer's ratio, a 1.8 mPas viscosity, a P50 of 2.8 kPa, a Hill coefficient of 2.1, a binding coefficient of 1.3 mL/g, a colloid osmotic pressure of 2.4 kPa, and a methemoglobin concentration of 3% Male-Sprague-Dawley rats undergoing an isovolumic blood exchange with this Pyr-Poly Hb solution, down to a 2% hematocrit, present a mean survival time of 20 h.

[Platelet preservation in a new type of plastic material. Functional in vitro study]. / Conservation des plaquettes dans un nouveau type de matériel plastique. Etude fonctionnelle in vitro.

We report the comparison of the fonctionnal platelet criteria's evolution studied in vitro by aggregation with different agents, by osmotic stress, ATP total amount and platelet volume distribution for six days of storage in two different PVC bags. The results indicate that: platelet's evolution appears more appreciable when tested by aggregation with an important amount of collagen, by hypotonic stress and volume distribution. The difference between the two different bags is shown as early as the thirs day of storage; for quality control, we can choose some criteria despite the absence of their clear correlation with transfusion efficiency.

[Rift valley fever and Zinga virus: a pathogenic arbovirus in man and animal new for Madagascar]. / Fievre de la vallee du Rift et virus Zinga: un arbovirus pathogene pour l'homme et l'animal nouveau pour Madagascar.

Virus Zinga strains have been isolated from several pools of mosquitoes collected in Perinet area, 130 km far from Tananarive, at the Institut Pasteur of Madagascar in 1980. Although this virus is pathogenic for man, it seemed to give only a mild illness and did not appear to constitute a problem of Public Health. But today it is seen in quite a different way; since the WHO Center for Arbovirus Reference and Research of New Haven has shown the serologic identity between virus Zinga and an another arbovirus, Rift Valley Fever virus. This latter is in fact very pathogenic for man and domestic animal, he is responsible of important epizootics characterized by many abortions in pregnancies and death of newborn animals, many infections have occurred in man during these epizootics and the disease is able to give a mortal haemorragic syndrome. Until now, no particular aggressivity has been shown by virus Zinga in Madagascar, but it remains a real potential danger for man and for domestic animals.

Arboviruses and lemurs in Madagascar: a preliminary note.

The epidemiological role played by lemurs in the circulation of arboviruses in Madagascar has been studied. From serological (HAI) tests, exposure of lemurs to alphaviruses and flaviviruses appears to vary considerably with location and species of lemur; positive tests varied from 0 to 32%. Finally, the data concerning the lemurophilic part of the mosquito fauna suggests that some lemur species and man are infected by the same arboviruses, especially West Nile virus. The susceptibility of these primates to yellow fever virus, which has not yet occurred in Madagascar is under study.