Glutamate dependent dendritic outgrowth in developing neuronal networks of rat hippocampal cells in vitro.

The present study was undertaken to determine whether release of glutamate is capable of influencing dendritic morphology in a developing network of rat hippocampal neurons in vitro. Control cultures developed a dense network of fibers and evinced spontaneous electrical activity from the third day in vitro. Dendrites were examined in cultures maintained for 2 weeks in vitro: the experimental group grown in medium containing the glutamate receptor antagonists AP-5 and DNQX. Dendritic extensions were analyzed as a function of time (days in vitro) using a number of morphometric parameters, vis. the number of processes, the number and length of intermediate and terminal segments, as well as the total length of all segments. We found that the effect of age and treatment was most prominently reflected in the length of the terminal segments. Chronic addition of ionotropic glutamate receptor antagonists from day 2 in culture arrested all dendrite parameters at the prefunctional level. The results suggest that glutamate release is crucial for the onset of dendritic morphological development in hippocampal neurons.

Transplantation of highly sensitized patients on the basis of acceptable HLA-A and B mismatches.

We think that the determination of acceptable mismatches is an efficient approach to increase the chance of finding a crossmatch-negative donor for highly sensitized patients. This approach has several advantages (4,5) namely: 1. There is no need for distribution of patient sera to other tissue typing centers. 2. Rather than performing crossmatches with all donors, most of which will be positive, selection is based on a predictable negative crossmatch. 3. Selection of potential donors is based on data obtained by the recipient centers, which has all the information concerning the patient's immunological background (transfusion, specific alloantibodies, autoantibodies) rather than on a negative crossmatch at another tissue typing center. 4. Selection is based on HLA-DR compatibility between donor and recipient, which is, both in our and other analyses (6), important for an optimal prognosis of graft survival in highly immunized patients. Of course, there are still patients for whom this protocol is not very helpful (rare HLA-types, hardly any or no acceptable mismatches). For these patients it might be that other approaches, including removal of circulating antibodies (7), may be the only solution.

[Treatment of choroid melanoma with contact curietherapy using ruthenium 106]. / Le traitement des mélanomes choroïdiens par curiéthérapie de contact avec le Ruthénium 106.

Recently, enucleation of choroidal melanomas tends to be replaced by less radical treatments such as photocoagulation. Use of Ruthenium 106 plaques has proved to be efficient in Germany. Because the Beta rays of Ruthenium 106 have only limited tissue penetration they are used only for tumors of less than 6-7 mm thickness and less than 18 mm2 surface. This report describes 62 cases of choroidal melanomas treated with Ruthenium 106. With a follow-up period of 12 to 48 months, 32 cases had total regression, including 2 cases with metastases. 15 patients required a second procedue and 15 had additional photocoagulation. In 23 of 51 patients the visual acuity remained unchanged. In 26 patients the visual acuity decreased and 2 patients had an improvement. 13 patients with melanomas inside or close to the macular area decreased their visual acuity.

Proteolytic dechorionation of annual fish embryos.

Incubation of early embryos of Nothobranchius korthausae in sterile Tris-buffered pronase with added salts and EDTA results in complete dechorionation, after which development proceeds normally and at the same rate as in control embryos. The time required for dechorionation varies according to the age of the embryo and the concentration of pronase employed.