Dorsal hippocampal function in unreinforced spatial learning.

This study examined learning about the spatial environment by rats during a single 10 min period of exploration on an eight-arm radial maze. Because no specific behaviors were learned during this procedure, the existence of learned spatial information was inferred from its retarding effect on subsequent conditioned cue preference (CCP) learning on the same maze. Previous experiments have shown that this form of spatial learning, measured in this way, requires an intact fimbriafornix and functional N-methyl-D-aspartate receptors. However, in the present experiments, large neurotoxic lesions of the dorsal hippocampus that impaired win-shift learning failed to eliminate the retarding effect of exploration on CCP learning. This result was obtained in three independent replications. These findings fail to confirm the hypothesis that the hippocampus is involved in spatial learning when that learning occurs in the absence of reinforcers and does not produce any specific learned behaviors. Previous work showed that this form of "pure" spatial learning requires an intact fimbria-fornix for acquisition but not for expression; the present findings suggest that the hippocampus is not required for either of these processes. The fimbria-fornix may interact with other temporal lobe structures in mediating this form of learning. The function of the hippocampus may be limited in some way to situations that involve reinforcers and/or situations in which specific behaviors are learned.

[Evaluation of the Coulter S + II in neonatology]. / Evaluation du Coulter S + II en néonatologie.

The Coulter Counter S + II is one of the most frequently used automatic counter in France. The authors evaluated its performances by analysing 116 blood samples from newborn infants aged less than one month. The reliability of this counter is impaired by the numerous rejects of lymphocytes or platelets and by the failure to recognize erythroblasts or circulating immature granulocytes. Moreover, abnormal cellular populations are notified which sometimes do not appear to be linked to any clinical disorder and are not evidenced by microscope examination control. These constatations bound the utilisation of this counter at least as far as the newborn's hematology is concerned.

[Transfusion strategy for patients in therapeutic aplasia. Experience of the Henri Mondor Hospital apropos of 2 successive protocols]. / Stratégie transfusionnelle pour les malades en aplasie thérapeutique. Expérience de l'Hôpital Henri Mondor à propos de 2 protocoles successifs.

Retrospective analysis of two transfusion protocols applied in our institution to the bone marrow transplanted patients was conducted. Granulocyte transfusions should be only proposed as a therapeutic treatment to patients with severe well documented bacterial infection resistant to an adapted antibiotherapy. Leukocyte-depleted blood products reduce the incidence of HLA-immunization but do not influence the frequency of CMV infections. Random single donor platelet concentrates (obtained by cytapheresis) could decrease the incidence of polyspecific HLA-antibodies in comparison with the use of random standard platelet concentrates. The best transfusion protocol should associate leukocyte-depleted blood products with transfusion of prophylactic single donor platelet concentrates. In our institution, this protocol is less expensive than the protocol with prophylactic white blood cell transfusions and has the same cost than other protocols using standard blood products.

Persistent remission of adult chronic autoimmune thrombocytopenic purpura after treatment with high-dose intravenous immunoglobulin.

Transient efficacy of high-dose intravenous immunoglobulin infusions (HDI) is widely demonstrated in autoimmune thrombocytopenic purpura (AITP). A trial involving repeated injections of HDI was conducted in two adult patients with chronic AITP in order to evaluate their long-term efficacy in refractory forms and their ability to obviate splenectomy. Both patients received 2 g/kg body weight of polyvalent intact intravenous immunoglobulin followed by seven and eight boosters (0.8 to 1.2 g/kg body weight) when the platelet count decreased. It was found that the injections could be spaced progressively. The platelet count remained normal 200 and 800 days after the end of the treatment. The demonstration of the possible long-term efficacy of repeated injections of intravenous immunoglobulin encourages us to recommend this safe therapy for patients with chronic AITP.

Human Fc(gamma) receptors for differentiation in throat cultures of group C "Streptococcus equisimilis" and group C "Streptococcus milleri".

The biochemical characteristics and the presence of human Fc(gamma) receptors of 52 throat isolates of group C beta-hemolytic streptococci were examined. Among these isolates, 38 were identified as "Streptococcus milleri" and 14 were identified as "Streptococcus equisimilis." The differentiation of group C "S. equisimilis" from "S. milleri" with identical group antigens was easy to perform by the measurement of the size of the hemolytic zone on a sheep blood agar plate in an anaerobic atmosphere and by biochemical tests (Voges-Proskauer test). A clear-cut criterion for differentiation was noted among these isolates, i.e., the presence of Fc(gamma) receptors. "S. equisimilis," which are generally associated with pharyngitis, possess human Fc(gamma) receptors, while "S. milleri", which are generally isolated from healthy persons, have no such receptors.