A cytogenetic study of the human chorion for the purpose of the prenatal diagnosis of hereditary diseases

Cytogenetical investigation of 50 diagnostic chorionic villus samples from women with a high risk of giving birth to babies with chromosomal and genic pathology, and of 128 chorionic samples obtained from medical abortions, both on the 8-12th weeks of gestation was performed by means of original direct chromosomal analysis. Chromosomal anomalies were found in 6 cases of diagnostic chorion biopsies (12%) and in 4 cases (3%) of medical abortions. The former group included 5 embryos with autosomal trisomy (4--Ts21 and 1--Ts13) and one embryo with monosomy 18. The latter group contained 2 embryos with X-chromosome monosomy and 2 other with chromosomal mosaicism. A significant prevalence of the female sex was found in the diagnostic group (sex ratio 0.56), but not in the medical abortion one (sex ratio 1.0). Analysis of routine chromosomal preparations and those after in situ hybridization with X-chromosome alfoid-probe YAP 1-10 revealed polyploidy in average in 0.8-1% chorion cells. The feasible causes of sex ratio distortion in embryos of diagnostic group and factors responsible for the rate of polyploidy are discussed. High reliability of originally elaborated direct "shaking-blotting" method of chromosomal preparations from chorionic villus samples is stressed.     

Dynamics of orientational tuning of feling visual cortex neurons under the effects of sombrevine

Dynamics of orientational tuning in 59 primary visual cortex neurons were investigated before and after sombrevine-induced anesthesia during acute experiments on immobilized cats using temporal slice techniques. A dynamic shift in preferred orientation of a flashing light strip, during which peak amplitude of spike discharges was noted (at an angle of between 22 and 157°) occurred as response developed in two-thirds of the cells. We had previously named this effect "scanning the orientational range" [9]. Scanning declined significantly in 45% of the sample, culminating in complete disappearance of this effect in some cells following sombrevine action. Scanning intensified in 30%, while dynamics of tuning remained unchanged in 25% of units. Sombrevine administration induced change in the preferred stimulus orientation of 60% of the neurons (referred to as "unstable" cells) and remained constant in "stable" cells (= 40%). Dynamic changes in preferred stimulus orientation were 2.5 times as high as those of stable cells in the waking state. The scanning effect declined significantly in 60% of "unstable" neurons under the action of anesthesia and remained unchanged in not more than 6%. At the same time, orientational tuning did not alter in the "stable" cell group in 46% of units, either declining (25%) or increasing (29%) in the remaining scanning ranges.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 1, pp. 107–113, January–February, 1990.     

Tuning for cruciform stimuli in visual cortex neurons of cat

In the primary visual cortex of an immobilized awake cat, nearly one-third of the neurons studied (8 out of 22) were found to respond to flashing cruciform light stimuli 1.5–4 times better than to single stimulations with the strips of preferred orientation. It is suggested that such neurons can detect angles and line intersections.Neirofiziologiya/Neurophysiology, Vol. 25, No. 5, pp. 362–364, September–October, 1993.     

Selective sensitivity of the cat striate neurons to cruciform and angular figures of various orientations

Selectivity and invariability of tuning were studied in 51 neurons of the primary visual cortex (area 17); cruciform and angular figures (CF and AF, respectively) of different configurations and orientations were presented in their receptive fields. Twenty-three neurons, or 45% of the studied cells, demonstrated selective sensitivity to these figures. Their responses considerably (2.38±0.36 times, on average) increased, as compared with those evoked by presentation of a single bar of preferred orientation. In the examined group, 2 cells demonstrated sensitivity both to the CF and AF. A wide range of detector properties related to the CF and AF analysis was found in the analyzed neuronal population. Detectors of configuration of these figures are described. Selective sensitivity to the angle between branches of these figures was observed in 17 neurons, and responses of 2 neurons among them showed invariability to orientation of these figures. Four cells were selective for orientation and were insensitive to configuration, and 4 other cells showed no specific sensitivity to either of these properties, but were sensitive to the appearance of a CF itself in their receptive field (these cells were regarded as invariant detectors of crossing nodes). Data inconsistent with the hierarchic principle of detection of the above properties are presented. Possible mechanisms and functional significance of selective sensitivity of striate neurons to the CF and AF are discussed.Neirofiziologiya/Neurophysiology, Vol. 27, No. 5/6, pp. 403–412, September–December, 1995.     

A reactivity to polyclonal stimulation of immunogenesis with salmozan after its repeated administration

The injection of 100 micrograms of salmozan (polysaccharide isolated from Salmonella typhi somatic O-antigen) or 50 micrograms of Escherichia coli lipopolysaccharide into mice induced a considerable increase in the number of antibody-forming cells in the spleen in response to the injection of sheep red blood cells (SRBC) 2-3 days later. This polyclonal effect was essentially weaker if the animals previously received 500 micrograms of salmozan (9-10 days prior to the injection of SRBC). The absence of reactivity was not linked with antibodies to salmozan or with some other serum factor. The lymphocytes of nonreactive mice proved to be capable of polyclonal response in the adoptive system, and at the same time the polyclonal response of intact lymphocytes to salmozan in the body of nonreactive irradiated mice was essentially weakened. The features making the above phenomenon similar to, as well as different from, the so-called "endotoxin tolerance" are analyzed.     

Proteolysis of the products of mitochondrial protein synthesis in yeast mitochondria and submitochondrial particles.

Degradation of mitochondrial translation products in Saccharomyces cerevisiae mitochondria was studied by selectively labelling these entities in vivo in the presence of cycloheximide and following their fate in isolated mitochondria. One-third to one-half of the mitochondrial translation products are shown to be degraded, depending on the culture growth phase, with an approximate half-life of 35 min. This process is shown to be ATP-dependent, enhanced in the presence of puromycin and inhibited by chloramphenicol. Further, the proteolysis is suppressed by detergents and is insensitive to antisera against yeast proteinases A and B when measured in mitochondria or 'inside-out' submitochondrial particles. It is concluded that the breakdown of mitochondrial translation products is most probably due to the action of endogenous proteinase(s) associated with the mitochondrial inner membrane. This proteinase is inhibited by phenylmethanesulphonyl fluoride, leupeptin, antipain and chymostatin.     

Age and changes in succinate dehydrogenase activity in functionally different muscles of the young rat

The antigravitational m. triceps brachii, its antagonist m. brachialis and the muscle having a universal functional specialization--m. serratus ventralis--have been studied in 35 male rats of Wistar strain, 60-105-day-old. Succinate dehydrogenase activity is determined in muscle fibers. Changes in the muscle fibers continue after the rats reach their sex maturation. Certain stageness of the process is observed, but the division of the period into separate steps either is absent (m. brachials), or their number is not great as compared to those during the 1st--60th days after birth. The borders of the periods in the muscles studied coinside (the 70th--74th day). Although it is possible to reveal the periods and separate steps in the changes occurring in the muscle fibers and in the muscles of the animals having reached their sex maturation, nevertheless, the borders between them are not distinct, the reconstruction during this age proceeds slower and more smoothely than before the sex maturation. It is possible that in young rats after sex maturation differentiation of the muscle fibers continues and that, in its turn, stimulates further specialization of the muscles as organs. The changes in the muscle fibers revealed histochemically occur most slowly under a low static loading, and when loading of various modality (kinetic and static) are combined, they are mostly pronounced.