Characteristic Features of Ultrafine-Grained Ti-45 wt.% Nb Alloy under High Cycle Fatigue.

The paper presents the results of fatigue-testing ultrafine-grained and coarse-grained Ti-45 wt.% Nb alloy samples under very high cycle fatigue (gigacycle regime), with the stress ratio R = -1. The ultrafine-grained (UFG) structure in the investigated alloy was formed by the two-stage SPD method, which included multidirectional forging (abc-forging) and multipass rolling in grooved rollers, with further recrystallization annealing.

[An experimental study of anti-amnestic activity of piracetam in orchidectomized rats].

The decrease of learning ability by 50% as assessed by passive avoidance test and the increase 28% of microviscosity of synaptosomal membranes from brain cortex were observed in rats in a month after orchidectomy as compared with that of intact or sham--operated animals. The treatment of orchidectomized rats with piracetam either by single application or in the course of 10 days applications in the daily dose of 250 mg/kg intraperitoneally failed to improve learning ability of animals in passive avoidance test and to produce a normalizing effect on the structure of membrane lipid matrix. The testosterone content in blood of orchidectomized rats was 10 times lower as compared with control and was not affected by treatment with piracetam.

[Effect of piracetam on rat reproductive function and the sexual development of their progeny].

Administration of piracetam to infantile rats in a daily dose of 100 mg/kg for 10 days caused acceleration of sexual maturation of females and a slight delay of maturation of males. Antenatal administration of the same dose of piracetam exerted a depressive action on the development of the organs of the reproductive system in males from the offspring with a simultaneous increase in the pituitary gonadotropic activity.

[Characteristics of the effect of 2-pyrrolidone acetamide (piracetam) on energy coupling in rat skeletal muscle mitochondria during cold stress].

Effects of 2-pyrrolidone acetamide (piracetam) on energetic state of mitochondria were studied in skeletal muscles of intact and ovaryectomized rats under conditions of drastic cooling (4 min swimming at 10 degrees). Readministration of piracetam was shown to cause uncoupling of oxidation and phosphorylation in mitochondrial respiratory chain (a decrease in respiratory control by Chance), as well as the drug increased the rate of O2 consumption in presence of oligomycin and decreased the uncoupler stimulating action on respiration in the group of intact animals. The alterations observed were most distinct in rats with cold stress, which was followed by piracetam administration, except of the rate of respiration stimulation, distinctly increased in presence of uncoupler.

[Clinical and experimental study of clofelin pharmacodynamics].

Hemodynamic mechanisms of clophelin hypotensive effect were studied in 122 patients with arterial hypertension. In most cases, antihypertensive clophelin therapy did not affect the nature or magnitude of orthostatic and stress-induced hemodynamic shifts. The fact that the fall in perfusion BP was not accompanied with a resting, orthostatic or stress-induced impairment of renal function was a particularly valuable aspect of clophelin treatment.

[Characteristics of the effect of piracetam on liver-mitochondrial respiration in intact and gonadectomized rats of both sexes].

It has been established in experiments on rats that subcutaneous administration of piracetam for 6 days in a daily dose of 100 mg/kg produces in intact but not in gonadectomized animals the following alterations in the system of oxidation and energetic coupling of liver mitochondria: a decrease in the magnitude of the respiratory control according to Chance, elevation of the rate of oxidation of NAD+-dependent substrates, a decrease in the stimulation of the rates of substrate oxidation by a disconnector, a rise of the rate of exogenous NADH oxidation by the amytal-antimycin A-resistant pathway. The action of piracetam described is pronounced to a greater degree in females than in males.

[Mechanisms of the inhibitory effect of clonidine on the reproductive system of female rats].

It has been demonstrated in experiments on puberal and infantile female rats that a single subcutaneous injection of clonidine (0.03 mg/kg) disturbed whereas in a dose of 1 mg/kg completely inhibited spontaneous or induced ovulation as well as sexual receptivity. When injected in a daily dose of 0.

[Action of 2-pyrrolidone acetamide (piracctam) on the electron transfer respiratory chain in rat liver mitochondria].

Repeated administration of 2-pyrrolidone acetamide (pyracetam; a structural analogue of GABA) at a dose of 100 mg/kg led to considerable alteration in systems of oxidative phosphorylation in liver mitochondria of intact rats. These alterations consisted in a decrease in the value of respiratory control when glutamate and malate were used as substrates, an increase in the rate of exogenous NADH oxidation in the amytal-antimycin A resistenant pathway and reduction in concentrations of cytochromes c, c1 and a. These effects were not observed in castrated rats.

Pregna-D'-pentaranes - a new class of active gestagenes.

A new class of modified progesterones with an additional ring in the 16 alpha , 17 alpha-position (pregna-D'-pentaranes) are described. Compounds containing 4- and 6-membered D'-ring (D'4- and D'6-pentaranes) were synthesized by the cycloaddition of acetylene or 1,3-butadiene, respectively, to the conjugated 16-double bond of 16-dehydro-20-keto steroids. The D'3-pentarane was prepared by the addition of diazomethane to the steroidal olefin followed by decomposition of the intermediate 16 alpha , 17 alpha-pyrazoline.

[Spin-label progesterone binding to serum albumin].

The binding of spin label progesterone to bovine serum albumin was studied by the spin-probe technique. The binding capacity of protein was established. It was shown that protein formed a rigid complex with steroid, the correlation time of this complex being 50 ns.

[Experimental study of the catatoxic effects of steroid hormones].

Tests set up on mice and rats brought evidence that spironolactone, progesterone, testosterone-propionate, methylandostendiol, desoxycorticosterone-acetate, methyltosterone, diethylstilbestrol, preparation PCN, megesterol-acetate and mestranol disply a catatoxic action, whose degree depends upon the method of evaluation and the animal species. A pattern for selection of catatoxic agents is proposed and some aspects of their mode of action are discussed.

[Study of the allergic properties of medicinal preparations in experiments].

Materials of an experimental study on allergenic properties of prolonged-action sulfanilamides and their semi-products are presented. Investigations involved the use of express-methods with intradermal administration of the substance into the ear and introduction of the agents together with the Freind adjuvant into the hind paw pad of a guinea pig. Experiments ascertained satisfactory dermal-allergic responses to the introduction of allergens differing in their strength by employing the above methods, as express ones for primary evaluation tof allergenic properties of drugs and their semi-products in conducting toxicological investigations.