Evidence for a change in the expression of beta2-microglobulin-assoicated membrane structures on leukaemic human cells.

Cell-associated and serum beta2-microglobulin was estimated in seven patients with chronic lymphocytic leukaemia. The amount of cell-associated beta2-microglobulin was significantly reduced (P less than 0.01), due to a decrease in the fraction of beta2-microglobulin that passes unretarded through a concanavalin A affinity column (presumably non-HLA-associated beta2-microglobulin). Serum concentrations of beta2-microglobulin were increased, but no correlation was found between the decrease in cell-associated beta2-microglobulin and the increase in serum beta2-microglobulin. All of the beta2-microglobulin from leukaemic serum was eluted corresponding to a molecular weight of 11,800 and none of it was retarded on a concanavalin A affinity column. The decrease in cell-associated beta2-microglobulin might reflect a change in the qualitative or quantitative expression of beta2-microglobulin-associated membrane structures on the leukaemic cells, perhaps conferring resistance to the cells against hypothetical immunological host defence mechanisms.     

RECOMBINATION FRACTIONS IN THE HLA SYSTEM BASED ON THE DATA SET ‘PROVINCES FRANÇAISES’: INDICATIONS OF HAPLOTYPE-SPECIFIC RECOMBINATION RATES

In the large genetic survey ‘Provinces Françaises’ the recombination fractions in the HLA system have been estimated by a family analysis programme (FAP). A total of 1332 families were analysed and in general the findings were in agreement with recombination fractions reported previously. The maternal recombination rates were on average 1.8 times higher than the corresponding ones for males. The comparison of the recombination fractions with the corresponding physical distances suggests the existence of hot spots of recombination. The analysis did not show deviations from expected values for HLA-A and B alleles on HLA-A/B recombinant haplotypes. However, analysis of HLA-B/DR recombinant haplotypes showed a skewed distribution of B and DR alleles. The significance of the findings is difficult to evaluate as all results are estimated numbers and frequencies but a manual analysis of the recombinant families confirmed the observations. HLA-B/DR recombinant haplotypes carried often HLA-DR3 and DR11 whereas DR2 and DR7 were more rarely present on recombinant haplotypes. DR4 had an increased incidence on BF/DR recombinant haplotypes but not on A/B or B/BF recombinant haplotypes. Some of the haplotypes with the strongest linkage disequilibria as A1, B8, DR3 and A3, B7, DR2 seem to be less frequently involved in recombinations than other haplotypes. Variations of recombination rates depending on certain alleles or haplotypes might partially explain the conservation of some haplotypes or part of haplotypes in Caucasoids.     

Influence of synchronous and sequential stimulation on muscle fatigue

In acute experiments the sciatic nerve of the rat is electrically stimulated to induce fatigue in the medial Gastrocnemius muscle. Fatigue tests are carried out using intermittent stimulation of different compartments (sequential) or a single compartment (synchronous) of the sciatic nerve. The activation of different compartments is achieved by dividing nerve fibres into subbundles and placing them in separate grooves in a multigroove electrode. The aim of the investigation is to quantify the effect of sequential contra synchronised stimulation in reducing muscle fatigue, with no overlap between compartments. Overlap between two compartments is calculated using the combined and individual forces from both compartments. Sequential stimulation of two and three compartments is investigated. There is a significant decrease of fatigue in sequential stimulation compared to synchronous. After 2 min of intermittent stimulation the force time level is significantly increased in sequential stimulation, than in synchronous stimulation. The rate of force time decrease is significantly slower in sequential stimulation than in synchronous stimulation. With sequential stimulation it takes significantly longer before the maximal force time is reached than with synchronous stimulation.     

The use of laparoscopic ovarian electrocautery in preventing cancellation of in-vitro fertilization treatment cycles due to risk of ovarian hyperstimulation syndrome in women with polycystic ovaries

Fifty women with polycystic ovaries took part in a prospective randomized study. All women required treatment by in-vitro fertilization (IVF) for reasons other than anovulation. They had all previously undergone ovarian stimulation with gonadotrophin therapy which had failed to result in pregnancy or had been abandoned due to high risk of developing ovarian hyperstimulation syndrome (OHSS). Twenty-five women were treated by long-term pituitary desensitization followed by gonadotrophin therapy, oocyte retrieval and embryo transfer (group 1). Twenty-five women underwent laparoscopic ovarian electrocautery after pituitary desensitization followed by gonadotrophin therapy, oocyte retrieval and embryo transfer (group 2). A significantly higher number of women in group 1 had to have the treatment cycle abandoned due to impending or actual OHSS, determined by endocrine and clinical findings. In addition, the development of moderate or severe OHSS in completed cycles was higher in group 1. The pregnancy rate and miscarriage rates in the two treatment groups were similar. The authors propose that laparoscopic ovarian electrocautery is a potentially useful treatment for women who have previously had an IVF treatment cycle cancelled due to risk of OHSS or who have suffered OHSS in a previous treatment cycle.      

Über die Verteilung von Radiostrontium in den Organen eines menschlichen Feten

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