[Episiotomy and prevention of complete and complicated tears. A study in 3 European countries]. / Episiotomie et prévention des déchirures complètes et compliqueées. Une étude dans trois pays européens.

The rates of third-degree tears in deliveries with and without episiotomy were compared in five samples: three French samples, a Belgian one and a Dutch one. Those samples corresponded to 48,430 single vaginal deliveries. The rates of episiotomy ranged from 29.3% to 54.2%. The results demonstrate that the risk of third-degree tears in vertex uncomplicated deliveries without episiotomy is low, and that in numerous cases third-degree tears are not prevented by an episiotomy. When uncomplicated deliveries of primipara were considered, results from four of the five samples showed that third-degree tears were not significantly more frequent in deliveries without episiotomy.

Biosynthesis of the ubiquinol-cytochrome c reductase complex in yeast. Discoordinate synthesis of the 11-kd subunit in response to increased gene copy number.

In wild-type yeast cells, steady-state concentrations of subunits of the ubiquinol-cytochrome c reductase complex (complex III) and the levels of their translatable mRNAs change coordinately in response to the need for mitochondrial function. Despite this, re-introduction of the cloned gene for one of the subunits (11 kd) into cells by transformation with a free-replicating plasmid results in the discoordinate synthesis of this subunit only, without effects on either the synthesis or degradation of the other subunits. The overproduced subunit is associated with the mitochondrial fraction, yet does not interfere with mitochondrial function, as judged by the growth of transformed cells on nonfermentable media. Quantitative analysis of both mRNA and protein levels suggests that both translational controls and elevated turnover of excess protein contribute to a partial compensation for the effects of increased gene dosage in transformed cells. These contain approximately 30 copies of the cloned gene and 15-30 times the normal level of its mRNA. Nevertheless, synthesis of the 11-kd protein is only 6- to 8-fold higher than normal, and steady-state levels are increased only 5- to 10-fold. These findings imply that synthesis of the various subunits of complex III is not tightly coupled and that for the 11-kd subunit at least, the level of mRNA is likely to be the most important means of regulating protein level. Fine-tuning may be additionally achieved by control of translation and degradation of excess protein which is not assembled in the complex.

Sexual agglutination factor from Chlamydomonas eugametos.

Chlamydomonas eugametos gametes can sexually agglutinate via their flagellar surfaces whereas vegetative cells cannot. Therefore, flagellar glycoproteins, present in gamete cells but absent from vegetative cells, were investigated as prospective mt (-)agglutination factors. They were identified as periodic acid Schiff (PAS) stained bands separated in sodium dodecyl sulphate-polyacrylamide electrophoresis gels. Gamete-specific bands were determined by comparison with equivalent gels of vegetative flagella and by immunological techniques using antisera raised against isolated mt (-) gamete flagella. Four high molecular weight flagellar glycoproteins proved to be gamete specific (PAS-1.2, PAS-1.3, PAS-3 and PAS-4). They were extracted from flagella by 3 M guanidine thiocyanate, separated in a column of Sepharose 2B, and tested for in vitro agglutination activity on mt (+) gametes. A single peak of activity was found to be correlated with the presence of the PAS-1.2 band. It is shown that mt (-) agglutination activity is related to the concentration of this glycoprotein in flagellar membranes.