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Biomedical subjects

A A Iakovlev

Publications and source records attributed to A A Iakovlev.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

[Statistical indices in medicine and epidemiology and their classification].

Mathematical statistics deals with abstract notions, while medicine solves complicated and many-sided problems. For this reason medical statistics faces some moot points in the interpretation of a number of notions and the classification of statistical indices. In the present article the definition of variables and statistical indices is formulated and their characterization is given. An attempt is made to provide the systematization and natural classification of the latter. Statistical indices are defined as the characteristics of statistical totalities. To classify statistical indices, the most essential signs are used: the character of a variable (external relations), the trend of study (internal content), the form of expression (calculation), derived indices and characteristics (comparison and the results of analysis).

Algorithms↗
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[Effects of intracerebroventricular administration of a caspase-3 inhibitor Z-DEVD-FMK on behavior of rats].

Rats received intracerebroventricular injections of z-DEVD-FMK (caspase-3 inhibitor) or z-FA-FMK (control peptide) in a dose of 3 nmol. Administration of z-DEVD-FMK significantly decreased the number of avoidance reactions in some blocks of trials in active avoidance (shuttle box) learning. However, only slight effect of the caspase inhibitor across the session was found. Z-DEVD-FMK impaired development of some essential components of the two-way active avoidance performance, such as escape reaction, conditioned fear reaction, and inter-trial crossings. Z-DEVD-FMK did not impair working memory in the spontaneous alternation behavior paradigm. Z-DEVD-FMK affected neither emotionality nor locomotor activity in the open-field test. It also did not influence behavior in the light-dark chamber. Measurement of caspase-3 activity in rat brain regions involved in active avoidance learning revealed z-DEVD-FMK-related inhibition of the enzyme activity most pronounced (about 30%) in the fronto-parietal cortex; a similar effect was close to significant in the hippocampus. The results suggest the involvement of brain caspase-3 in selected forms of learning.

Animals↗
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[Nitric oxide synthase activity and nitrates/nitrites level in brain regions during the spontaneous morphine withdrawal in rats].

Nitric oxide synthase (NOS) activity and nitrate/nitrites (NO(x)-) concentrations were measured in brain regions of rats during the spontaneous morphine withdrawal. Male Wistar rats were injected intraperotoneally with morphine hydrochloride at increasing doses (10-100 mg/kg) during 6 days twice a day. Thirty six hours after the last injection the severity of the spontaneous morphine withdrawal syndrome was determined by specific autonomic and locomotor indices. Both NOS activity and NO(x)- levels increased in the midbrain and the hippocampus, decreased in the striatum and the hypothalamus, and did not change in the cerebral cortex and the brain stem. NO(x)- concentrations in the cerebellum did not change, while NOS activity decreased. Both NOS activities and NO(x)- concentrations in the cerebral cortex, striatum, midbrain, and cerebellum correlated with withdrawal syndrome severity on the whole, and with the specific signs of abstinence.

Animals↗
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[Adrenocorticotropic function of the pituitary gland in endocrine diseases].

In examination of 123 patients with diabetes mellitus. Itsenko-Cushing disease, Addison's disease, thyrotoxicosis and adiposity there was revealed an increase in the content of the adrenocorticotropic hormone (ACTH) in the blood. Comparison of the ACTH and cortizol concentration in the blood permitted to suppose a different mechanism of the derangements revealed. An increase of the adrenocorticotropic function of the hypophysis in diabetes mellitus, Itsenko-Cushing disease and thyrotoxicosis was accompanied by a rise in the blood cortizol level. A fall of glucocorticoid function of the adrenal glands in Addison's disease and a relative hypocorticism in the patients with adiposity caused a compensatory intensification of the ACTH secretion.

Addison Disease↗
PubMedDate not supplied

[Assessment of retinal function in cataract by electroretinography].

Electroretinography (ERG) was used to assess the functions of the retinal central and peripheral sections in patients with cataracts of various origins and different degrees of opacities; the method is based on the use of 18-20 degrees red saturating stimulus fit in sucker electrode for macular ERG and Hanz-Feld white stimulus for total ERG. Macular biopotential recorded in the patients with mature cataracts without pathologic changes in the macular region coincided with the mean values of local macular ERG recorded in transparent ocular media with medium-intensity stimuli. Macular biopotentials in cataracts significantly differed from the normal values in dystrophic changes of the macular area. Total ERG values in transparent ocular media and in mature cataract patients coincided only in with saturating white stimulus in cases when no retinal abnormalities were present. ERG with weak and medium-intensity stimulating light has shown has shown a significant difference of ERG parameters in these patient populations. Analysis of ERG findings in 375 patients with cataracts of various origins and with various opacity degrees has shown the possibility of extrapolating the data on ERG symptoms of retinal abnormalities known in transparent ocular media to the diagnosis of the pathologic processes in the retina when the fundus of the eye cannot be seen; this method will be useful in predicting visual functions in the postoperative period.

Adolescent↗
PubMedDate not supplied

[Effectiveness of magnetotherapy in optic nerve atrophy. A preliminary study].

Magnetotherapy effects on visual functions (vision acuity and field), on retinal bioelectric activity, on conductive vision system, and on intraocular circulation were studied in 88 patients (160 eyes) with optic nerve atrophy. A Soviet Polyus-1 low-frequency magnetotherapy apparatus was employed with magnetic induction of about 10 mT, exposure 7-10 min, 10-15 sessions per course. Vision acuity of patients with its low (below 0.04 diopters) values improved in 50 percent of cases. The number of patients with vision acuity of 0.2 diopters has increased from 46 before treatment to 75. Magnetotherapy improved ocular hemodynamics in patients with optic nerve atrophy, it reduced the time of stimulation conduction along the vision routes and stimulated the retinal ganglia cells. The maximal effect was achieved after 10 magnetotherapy sessions. A repeated course carried out in 6-8 months promoted a stabilization of the process.

Adolescent↗
PubMedDate not supplied

[Effect of the dopamine agonist parlodel on steroid hormone secretion and their metabolism in the liver].

Experiments on rats have shown that the dopamine agonist parlodel produces a noticeable inhibitory effect on function of the pituitary-adrenal system by a decrease in corticotropin secretion and direct influence on aldosterone synthesis and secretion. Changes in corticosterone level caused by parlodel are related to ACTH action and inhibition of activity of the microcirculatory bed of the adrenal fascicular zone. The dopamine agonist parlodel produces no effect on metabolism of the steroid hormones: corticosterone and testosterone in the rat hepatic tissue.

Adrenal Glands↗
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[Effect of a single dose of parlodel on the secretion of various hormones in Itsenko-Cushing disease].

The results of investigation of the secretion of hypophyseal, adrenal and renal hormones resulting from parlodel administration in 44 patients with Itsenko-Cushing disease were discussed. Concentrations of corticotropin (ACTH), prolactin, somatotropin (STH), thyrotropin (TSH), cortisol, aldosterone, adrenalin, noradrenaline, dopamine and blood renin activity were determined by radioimmunoassays and radioenzymatic methods on an empty stomach and 30, 60 min., 2, 4 and 24 h after parlodel administration (2.5 mg) per os. Parlodel administration in Itsenko-Cushing disease was shown to cause a decrease in the secretion of hypophyseal hormones (ACTH, prolactin and STH). The level of cortisol raised before the start of the investigation was gradually decreased after the drug administration and reached its minimum in 2-4 h. Correlation of the basal level of aldosterone and blood renin activity, and a response of the renin-angiotensin-aldosterone system to parlodel administration was revealed. Changes in the secretion of catecholamines were of diverse nature: a decrease in the blood concentration of noradrenaline in the absence of adrenalin and dopamine shifts.

Adrenocorticotropic Hormone↗
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[Mechanisms of action of beta-endorphin on the secretion of hypophyseal hormones].

The purpose of the study was to investigate some mechanisms of the effect of beta-endorphin on somatotropic and lactotropic function of the hypophysis, adrenal activity and the content of catecholamines in the cerebral tissues. Activation of the hypophyseoadrenal system, lactotropic and somatotropic functions 5-20 min after beta-endorphin administration was established in experiments on male rats. At the same time a decrease in the content of catecholamines in the hypothalamus, cerebral cortex was observed. It was most significant for dopamine participating in the regulation of ACTH, prolactin and somatotropin secretion.

Adrenal Cortex Hormones↗
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[Changes in the activity of enzymes of renin-angiotensin and kinin systems in the rat brain after adrenalectomy and administration of hydrocortisone].

It is shown that the activity of enzymes participating in renin-angiotensin and brain kinin systems' metabolism depends on functional state of hypothalamo-pituitary-adrenocortical system. Under experimental hypocorticism the activity of angiotensin-converting enzyme and kininase I in the hypothalamus, hippocamp, corpus striatum and rat pituitary decreases; the renin-like enzyme activity decreases in the corpus striatum but increases in the hypothalamus and hippocamp. After hydrocortisone administration to adrenalectomized rats the angiotensin-converting enzyme activity of the hippocamp and pituitary is shown to be normalized as well as renin-like enzyme and kininase I of the hippocamp and corpus striatum. The activity of the studied enzymes in the hypothalamus decreases in this case.

Adrenalectomy↗
PubMedDate not supplied

[Experimental and clinical basis for using the preparation nacom in the treatment of Itsenko-Cushing disease].

The paper is concerned with the results of an experimental study of the nacom (NC) effect on the activity of the hypothalamohypophysioadrenal system and the results of its application to 29 patients with Icenko-Cushing's disease with curative purposes. In rats the concentration of corticotropin and aldosterone was determined with a radioimmunoassay, that of corticosterone with a competitive protein binding method. The dopamine content in the hypothalamus and cerebral cortex was studied by fluorimetry. To define the hypothalamohyphysioadrenal system in the patients a study was made of blood corticotropin, cortisol and aldosterone basal levels as well as response of the system to insulin hypoglycemia induced stress. Dopaminergic NC was shown to be dose-related with the activity of the hypothalamohypophysioadrenal system. The NC effect was associated with an increase in the dopamine level in the hypothalamus and cerebral cortex. Clinical investigations proved NC efficacy for therapy of Icenko-Cushing's disease permitting one to recommend it as a pathogenetic agent for therapy of this disease.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

[Effect of hydrocortisone on the activity of angiotensin-converting and renin-like enzymes and kininase I in the brain and hypophysis of rats].

The paper is concerned with a study of the effect of an excess of corticosteroids in the body, resulting from single and multiple hydrocortisone administration to rats, on the activity of enzymes involved in the pathway of the renin-angiotensin and kinin systems in different parts of the brain and hypophysis. Hydrocortisone administration to rats resulted in an increase in the activity of the angiotensin converting enzyme in the hypothalamus, hippocamp, striate body and hypophysis, an increase in the renin-like activity in the hypothalamus and hippocamp and its decrease in the striate body. The nature of changes in kininase I activity after the hormone administration was different in the examined parts of the brain. The results obtained indicated that one of the links in the mechanism of corticosteroid action on the renin-angiotensin and kinin system of the brain was the effect of these hormones on the activity of the renin-like, angiotensin converting enzymes and kininase I.

Animals↗