The effect of deoxycholate on yeast cell permeability

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   Мембраны ненарушенных клеток дрожжей непроницаемы для солей янтарной кислоты и феррицианида, так что в их суспензии не наблюдается сукцинодегидрогеназы с феррикианидом как акцептором электронов.     

Hormonal imprinting in cell culture II. Evidence of hormonal imprinting and thyrotropin (TSH) -gonadotropin (FSH) overlap in a Chinese hamster ovary (CHO) cell line

Reexposure of cultures of the Chinese hamster ovarian cell line CHO K1 to FITC-labeled hormone 48 h after the first 24-h exposure to FSH or TSH showed that hormonal imprinting, accounting for a greater binding capacity on reexposure, also took place in in vitro conditions. TSH amplified the receptors of FSH to a greater degree than FSH itself, although the reverse effect failed to happen. TSH was able to bind the ovarian cells at first exposure, and to amplify the receptors for itself and--remarkably--to a considerably greater degree for FSH, exactly as observed earlier in in vivo systems.     

Study of the imprinting and overlap of insulin and concanavalin-A at the receptor level in a protozoan (Tetrahymena) model system

In a protozoan (Tetrahymena) model system, insulin treatment produced a long-term imprinting which upon re-exposure to the hormone resulted in an enhanced binding of the hormone. Insulin pretreatment produced similar effect with regard to the binding of concanavalin-A. Concanavalin-A could only induce a short-term imprinting for itself and was not capable at all of inducing imprinting for insulin. Based on the results of this study it appears that the binding of the sugar component of the receptor, which can be achieved also by lectin, is not sufficient to induce imprinting but the whole (hormone) molecule is needed.     

Intracellular oxygen tension and energy metabolism in the cat brain cortex during haemorrhagic shock.

The changes in intracellular oxygen tension and energy metabolism of the cat brain cortex were studied by surface fluororeflectometry during haemorrhagic shock. The results may be summarized as follows. (a) Intracellular oxygen tension, i.e. the maximum cortical NAD reduction obtained during nitrogen gas inhalation decreased gradually during the hypovolaemic phase of shock and finally, the brain cortex became ischaemic. (b) Partial uncoupling of the cerebrocortical mitochondrial respiration and oxidative phosphorylation appeared in the very early period of bleeding, as indicated by the overshot of the cortical NAD/NADH redox state towards oxidation subsequent to the cessation of nitrogen gas inhalation. Partial uncoupling of mitochondrial respiration and oxidative phosphorylation became more pronounced during the later phases of bleeding, finally, the mitochondrial electron transport stopped. In line with these changes the frequency and the amplitude of ECoG decreased gradually and markedly during the hypovolaemic phase of shock. (c) Microcirculation and energy metabolism of the cat brain cortex were severely and irreversibly damaged during the hypovolaemic phase of shock. This was clearly shown by the fact that in the majority of experiments the nitrogen anoxia after reinfusion failed to bring about changes in the cortical NAD/NADH redox state and the ECoG changes occurred during bleeding did not improve after reinfusion. It is concluded that the early disturbances of cerebrocortical energy metabolism play an important role in the development of neural and vascular lesions of the brain that occur during haemorrhagic shock.     

Effect of ovarian steroid hormones on superficial activator calcium in the rabbit uterus.

Effect of oestradiol (E2) and progesterone (P) on activator calcium binding was studied in the rabbit uterus. Superficial Ca-binding of isolated uterine strips was characterized by determining the rate of loss of isometric tension evoked by low (2.4 V/cm) field strength electrical stimulation in Ca-free Krebs solution. Intramuscular injection of 10 mg P increased superficial Ca-binding significantly in the postpartum and E2-treated virgin uterus with a latency period of 8--12 hours. Bilateral ovariectomy on the 25th day of pregnancy decreased superficial Ca-binding progressively, which could be avoided by P-substitution. 72 hours after ovariectomy P-treatment failed to increase Ca-binding. Local application of cycloheximide increased Ca-binding in the E2-treated virgin uterus. The results suggest that a high P-level plays an important role in the induction and maintenance of a strong binding of superficial activator calcium in the rabbit uterus. Progressive disappearance of the strong binding near term and after bilateral ovariectomy correlates well with P-withdrawl in this species.     

Calcium distribution and exchange in the pregnant and post partum rabbit uterus

Calcium content and distribution of the 25-day pregnant (PR) and post partum (PP) rabbit uterus was studied by atomic absorption spectrophotometry and 45Ca determination. Total Ca content [2.28 +/- 0.28 (PR) and 2.19 +/- 0.12 (PP) mM/kg wet wt] extracellular [1.21 +/- 0.09 (PR) and 1.25 +/- 0.11 (PP) mM/kg wet wt] cellular [1.07 +/- 0.08 (PR) and 0.94 +/- 0.09 (PP) mM/kg wet et], total exchangeable [1.86 +/- 0.11 (PR) and 1.84 +/- 0.09 (PR) mM/kg wet wt] and inexchangeable [0.43 +/- 0.05 (PR) and 0.35 +/- 0.04 (PP) mM/kg wet wt] Ca fractions were identical in the two extreme endocrinological conditions. In contrast compartment size and rate constant of different exchangeable Ca fractions determined by kinetic analysis of 45Ca desaturation "urves (curve-peeling tecnique and computer method), revealed significant differences between PR and PP uteri. Two exchangeable phases could be identified in both endocrinological states. The rate constants of both phases of efflux were significantly higher in the PP (alpha 1 = 0.173 +/- 0.02 min-1; alpha 2 = 0.023 +/- 0.001 min-1) than in the PR uterus (alpha 1 = 0.099 +/- 0.01 min-1; alpha 2 = 0.018 +/- 0.01 min-1). Compartment size of phase 1 (fast component) was significantly higher in the PR (1.13 +/- 0.1 mM/kg wet wt) than in the PP uterus (0.77 +/- 0.06 mM/kg wet wt). In contrast, compartment size of phase 2 (slow component) was significantly smaller in PR than in PP uterine strips (0.74 +/- 0.06 and 1.08 +/- 0.11 mM/kg wet wt). The last portion of desaturation curves represents efflux from one homogenous compartment. The present results suggest that endocrinological control of the rabbit myometrium is linked to the regulation of the binding of a superficial exchangeable Ca fraction.     

Ontogeny of lymphatic structures in the pig omentum

Summary The development of lymphoid populations in the omentum majus during the prenatal and postnatal life of the pig was studied. T lymphocytes, monocytes and mast cells were first found on the 40th day of gestation. B lymphocytes appeared on the 72nd day of gestation when the first macrophage aggregates were formed. Macrophages appeared to be the prerequisite for the formation of dense lymphatic areas (DLA's). At later stages T cells were observed only in the omentum of germfree pigs. DLA's of conventional pig omentum are filled exclusively with B cells.     

Genetic determination of the mitochondrial adenine nucleotide translocation system and ITS role in the eukaryotic cell

On integrating experimental data published previously, the following picture of the mitochondrial adenine nucleotide (AdN) translocation system is being presented: 1. The AdN translocation system serves not only to transport ATP synthesized within mitochondria into the cytosol but also to transport cytosolic ATP into the mitochondria when oxidative phosphorylation is not functioning. 2. The AdN translocator is coded for by nuclear genes and the mitochondrial protein synthesis is not involved in its formation. 3. The AdN translocation system must be preserved and functioning even in cells which could dispense with oxidative phosphorylation. It assures appropriate concentrations of intramitochondrial ATP. 4. The intramitochondrial ATP is required for normal replication of mitochondrial DNA. Tis supports the view that the mitochondrion is a self-replicating semi-autonomous organelle. 5. The appropriate concentration of ATP must be present in mitochondria to make possible cell growth or multiplication. This points to a direct or indirect role of mitochondria in the control of cell proliferation.