Features of α2-Adrenergic Regulation of Isolated Rat Heart after Hypokinesia.

We studied the effect of the α2-adrenergic receptor agonist clonidine hydrochloride (10-9-10-6 M) on the isolated heart of adult rats after 30-day restriction of motor activity. In hypokinetic rats, in comparison with control animals, clonidine caused a positive inotropic effect; the dynamics of coronary flow was changed after stimulation of α2-adrenergic receptors by clonidine in the minimum and maximum concentrations. Moreover, clonidine in concentrations of 10-8 and 10-7 M reduced coronary flow both in the control group and against the background of hypokinesia. Clonidine (10-8-10-6 M) had a negative chronotropic effect in control and hypokinetic animals, while the dynamics of HR was multidirectional, i.e. either an increase or decrease in the effects was observed depending of the agonist concentration. Overall, the data obtained indicate the participation of α2-adrenergic receptors in adaptive processes after motor activity limitation.

[Individual learning curves for microsurgical myocardial revascularization]. / Individual'nye krivye obucheniia mikrokhirurgicheskoi revaskuliarizatsii miokarda (s kommentariem).

AIM: To create individual learning curves for microsurgical myocardial revascularization. MATERIAL AND METHODS: It was analyzed duration of the individual stages of the first 100 CABG procedures which were performed using microsurgical technique and surgical microscope. Graphs reflecting correlation between duration of the individual surgical stages and their number were framed. RESULTS: Improvement in distal anastomosis time, aortic cross-clamping time, cardiopulmonary bypass time and duration of surgery was observed with increased surgeon's experience. CONCLUSION: Individual learning curves objectively characterize the learning process of microsurgical myocardial revascularization, allow to estimate the time need for improvement of cardiac surgeons' qualification and demonstrate dates for achieving average surgical quality during learning the technique.

[Dynamics of a green oak moth population: application of discrete-continuous models with a nonmonotone density-dependent birth rate].

Considered is a mathematical model for dynamics of an isolated population with non-overlapping generations. The individuals' birth process (emergence of new-generation individuals) is assumed to have a discrete nature (there exist some fixed time moments at which the new generations emerge), while the death process is assumed to be continuous. In addition, the birth rate is assumed to be a function of the number of individuals survived till the moment of reproduction, the function being non-monotone: there exists an optimal value of the population size at which the birth rate reaches its maximum (Alley principle). Analysis of the discrete-continuous models has revealed that each of the new models has a rich set of dynamical regimes. New models are compared with a number of well-known discrete ones (like Skellam, Moran-Ricker, Hassell, Maynard Smith-Slatkin models, and others) when approximating an empirical time series on fluctuations of a green oak moth population (Korzukhin, Semevsky, 1992). Neither of the models can provide for a satisfactory description of the green oak moth dynamics. It is also shown that usage of the discrete-continuous models for approximation of real datasets enables one to find several important population parameters, which can hardly (or cannot) be found by means of traditional discrete models.

Sildenafil inhibits hypoxia-induced pulmonary hypertension.

BACKGROUND: This study investigated the effect of the phosphodiesterase 5 inhibitor sildenafil on the pulmonary vascular response to hypoxia in humans and mice. METHODS AND RESULTS: In a randomized, double-blind study, sildenafil 100 mg or placebo was given orally to 10 healthy volunteers 1 hour before breathing 11% O(2) for 30 minutes. Pulmonary artery pressure (PAP) was measured with an indwelling right heart catheter. The acute 56% increase in mean PAP produced by hypoxia during placebo treatment (mean PAP [mean+/-SD mm Hg]: normoxia 16.0+/-2.1 versus hypoxia 25.0+/-4.8) was almost abolished by sildenafil (normoxia 16.0+/-2.1 versus hypoxia 18.0+/-3.6), with no significant effect on systemic blood pressure. In the isolated perfused lung of wild-type and endothelial nitric oxide synthase (eNOS)-deficient mice, sildenafil markedly blunted acute hypoxic pulmonary vasoconstriction. Wild-type mice dosed orally with the drug (25 mg. kg(-1). d(-1)) throughout 3 weeks of exposure to hypoxia (10% O(2)) exhibited a significant reduction in right ventricular systolic pressure (placebo versus sildenafil: 43.3+/-9.9 versus 29.9+/-9.7 mm Hg, P<0.05) coupled with a small reduction in right ventricular hypertrophy and inhibition of pulmonary vascular remodeling. In eNOS mutant mice, sildenafil attenuated the increase in right ventricular systolic pressure but without a significant effect on right ventricular hypertrophy or vascular remodeling. CONCLUSIONS: Sildenafil attenuates hypoxia-induced pulmonary hypertension in humans and mice and offers a novel approach to the treatment of this condition. The eNOS-NO-cGMP pathway contributes to the response to sildenafil, but other biochemical sources of cGMP also play a role. Sildenafil has beneficial pulmonary hemodynamic effects even when eNOS activity is impaired.

[Characteristics of pneumonia in patients with pulmonary tuberculosis]. / Osobennosti techeniia pnevmonii u bol'nykh tuberkulezom legkikh.

In healed tuberculosis, pneumonia more frequently arises in the zones of pronounced residual changes. In active tuberculosis combination of tuberculosis with pneumonia often takes place in intact bronchopulmonary segments. Pneumonia in tuberculous patients takes a lingering course in the presence of pneumosclerotic changes in the lungs, tends to acquire bronchial forms, is characterized by slow involution of inflammation, runs atypically in combination of pneumosclerotic changes in the lungs, bronchial stenoses and abnormal cell composition of bronchoalveolar washout. The diagnosis and treatment present difficulties in pneumonia location in the zone of distinct post-tuberculous pneumosclerosis with small segmental lesion. Resolution of inflammatory foci in the lungs in lingering pneumonia may course as long as 8-10 weeks.

[Effectiveness of the treatment of patients with fibrous-cavernous pulmonary tuberculosis]. / Effektivnost' lecheniia bol'nykh fibrozno-kavernoznym tuberkulezom legkikh.

The follow-up of 301 patients with fibrous-cavernous pulmonary tuberculosis has demonstrated that the disease outcome and treatment effectiveness depend on the nature of its course. A long-term specific therapy for 9-10 months brings about cessation of bacillary excretion in 50-60% of cases even in a progressive course of the disease and closure of destruction cavities occurred in 12.5% of cases with rapid progression and in 21.7% of cases with slow progression of the disease. Despite all measures taken, stabilization of the process fails in one-fourth of the patients with rapidly progressing fibrous-cavernous tuberculosis and in 9% of those with a slowly progressing course. In 90% of cases bacillary excretion in patients with stable fibrous-cavernous tuberculosis ceased in 3 months and in 100% after 6 months of treatment.

[The bacterial excretion dynamics of patients with fibrous-cavernous pulmonary tuberculosis]. / Dinamika bakteriovydeleniia u bol'nykh fibrozno-kavernoznym tuberkulezom legkikh.

A study of 294 patients with fibrous-cavernous pulmonary tuberculosis revealed that massive bacteria elimination and drug polyresistance is found in patients with advancing and complicated course of the disease. It was established that after a nine-months course of treatment bacteria elimination was observed in 50% of patients with advancing fibrous-cavernous pulmonary tuberculosis.

[Variants of the course of fibrous-cavernous pulmonary tuberculosis]. / Varianty techeniia fibrozno-kavernoznogo tuberkuleza legkikh.

Taking into account the presence of the process development symptoms or their absence (including a high rate of exacerbations, ongoing dissemination process, formation of new cavities in the affected foci, severe infiltration of the lung tissue and massive bacillary excretion), process development rate and the nature of complications, the following 4 versions of fibrous-cavernous pulmonary tuberculosis were identified: rapidly developing disease; slowly developing disease; fibrous-cavernous pulmonary tuberculosis whose clinical picture was determined by different complications; and relatively stable condition. ++Clinico-roentgenological+ features of each version of the disease are described. Abnormalities in the ++clinico-roentgenological+ picture and laboratory findings are especially apparent in patients with rapidly developing fibrous-cavernous pulmonary tuberculosis.

[The results of treating fibrous-cavernous tuberculosis in patients with different genetic markers]. / Rezul'taty lecheniia fibrozno-kavernoznogo tuberkuleza u bol'nykh s razlichnymi geneticheskimi markerami.

Overall 221 patients with fibrous-cavernous tuberculosis were examined. In patients carrying Hp 2-2 haptoglobin and HLA DR2, the disease runs an unfavourable course more frequently. Among the patients with Hp 2-2, the positive dynamics was attained by the 6th month of the treatment in 44.1%, among those with HLA DR2 in 42.3% of cases while in patients carrying the two genetic markers at a time, in only 32.4% of cases. Patients with Hp 2-2 and HLA DR2 require special attention of the treating physician since the very first day of the disease and use of every possible treatment methods.

[Effect of Argiope lobata venom and its components on L[3H)glutamate binding with locust muscle membranes]. / Deistvie iada pauka Argiope lobata i ego komponentov na sviazyvanie L[3H]glutamata s membranami myshts saranchi.

The Argiope lobata venom is shown to block synaptic potential at locust neuromuscular junctions and inhibit the high-affinity sodium independent L[3H]glutamate binding site in locust muscle membranes. The data obtained due to fractionation of venom evidence that it contains components which block synaptic potential and inhibit the binding of L[3H]glutamate (5 kDa and more) as well as components which block synaptic potential but do not inhibit the binding of L[3H]glutamate less than 5 kDa. These observations indicate that spider venom contains at least two components with different mechanism of action.

[Interrelations of genetic markers (HLA antigens and haptoglobin variants) and the course of fibrous-cavernous pulmonary tuberculosis]. / Vzaimosviaz' geneticheskikh markerov (antigenov HLA i variantov gaptoglobina) i techenie fibrozno-kavernoznogo tuberkuleza legkikh.

Altogether 72 patients with different variants of a course of fibrous-cavernous pulmonary tuberculosis were investigated for the presence of HLA antigens and Hp phenotypes. It was shown that an increase in the frequency of antigen DR2 and Hp 2-2 could be used as a prognostic prerequisite in the assessment of a course of disease.

[Toxic components of the venom of the cellar spider Segestria florentina]. / Izuchenie toksicheskikh komponentov iada pogrebnogo pauka Segestria florentina.

Two neurotoxins and one insectotoxin have been isolated from venom of the cellar spider Segestria florentina, their homogeneity being proved by disk electrophoresis, isoelectric focusing, and analysis of N-terminal amino acid residues. The neurotoxins are polypeptides with molecular mass about 5000 D. For the insectotoxin, containing 35 amino acid residues with molecular mass 3988 D, the total primary structure is established.

[Effect of the phase state of lipids on their interaction with cobra cytotoxin]. / Vliianie fazovogo sostoianiia lipidov na ikh vzaimodeistvie s tsitotoksinom kobry.

Interaction between cytotoxin of the Central Asia cobra venom and dimiristoylphosphatidylcholine bilayer depending on its phase state was studied by ESR with spin label. A conclusion can be drawn that the efficiency of cytotoxin effect on the membranes depends on their phase state. Cytotoxin molecules are incorporated into myophile region of the bilayer, only if the latter is in the liquid crystal state. The interaction between cytotoxins and lipids of the bilayer in a gel state is in the main conditioned by electrostatic forces.