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Biomedical subjects

I N Lavrova

Publications and source records attributed to I N Lavrova.

9 recordsLinked to original sources
PubMed2006

[Cardiorespiratory responses of animals to passive orthostasis after intermittent hypoxia during head-down tilt].

Cardiorespiratory responses induced by upright tilt before and after intermittent hypoxia during head-down tilt, were investigated in rabbits. Arterial blood pressure, heart rate, central venous pressure, transmural filling pressure of the heart (calculated as the product of esophageal and central venous pressure), breathing frequency, esophageal pressure were measured in supine (baseline), head-down and upright posture. Our results indicate a reduction in orthostatic responses in cardiovascular system after intermittent hypoxia.

Animals↗
PubMed2005

[The dynamic of breathing biomechanics and intrathoracic hemodynamics parameters during microgravity modeling].

In ground-based model of the hemodynamics effects of weightlessness, the intersystem relation of breathing and circulation was investigated during inspiration and expiration separately in anesthetized catz. It's shown that the dynamics of central venous pressure, esophageal pressure and filling pressure of the heart during inspiration in supine and head-down tilt position has obvious similarity to those which hypothetically can be present in microgravity. The results suggest that intrathoracic hemodynamics during inspiration in supine and head-down position may be an adequate ground model for investigation of weightlessness influences on intrathoracic circulation.

Animals↗
PubMed2003

Influence of changes in intrathoracic and central venous pressure on cardiac filling dynamics.

Changes in the ratio between intrathoracic and central venous pressure were studied in narcotized cats under conditions of constant positive or negative pressure ventilation. Transformation of elastic characteristics in the respiratory system caused by changes in intrathoracic pressure led to inversion of the ratio between transpulmonary intrathoracic and central venous pressure determining right atrial filling pressure.

Animals↗
PubMed2003

[Respiration and cardiovascular mechanisms of hypobaric correction of the head-down redistribution of local blood volumes].

The focus was placed on the physiological mechanisms of correction of the blood redistribution during the head-down tilt (HDT) with a discrete or complex use of the methods of negative pressure respiration (NPR) and lower body negative pressure (LBNP). It was evidenced that rise in the intracranial hydrostatic pressure in HDT (-6 degrees) can be compensated by NPR within a range of -10 to -15 cm of water column causing decrease in the intrasternal pressure from -5.04 to -7.74 cm w.c. Bioimpedance and ultrasonic investigations led to the conclusion that the decreased transpulmonary pressure is responsible for blood outflow from the intracranial venous system till the level adequate to the horizontal position of the body. The results were verified in experiments with unconscious cats: pressure in the exterior jugular vein and v. cava superior during HDT (-30 degrees) with NRP at -5 cm w.c. decreased by 3.2. and 4.3. w.c., respectively. Experiments with human subjects also demonstrated that the complex use of NPR and LBNP produces an additive hemodynamic effect and can be considered a new method for correcting the adverse consequences of redistribution of the local blood volumes toward the head end.

Adult↗
PubMed2000

[Effect of the body antiorthostatic posture on various circulation and respiration parameters in anesthetised cats].

In anaesthetised cats, antiorthostatic posture of the body with an inclination angle of 30 degrees increased pressure in the vena cava superior and in jugular vein. The rest of the cardio-respiratory parameters were changed insignificantly. Physical and physiological mechanisms of the blood regional redistribution in alteration of the body gravitation orientation, are discussed.

Anesthesia↗
PubMed2000

[Influence of breathing at negative pressure on redistribution of local blood volumes in anti-orthostatic load in cats].

To improve methods of offsetting the hemodynamic shifts in microgravity, applicability of breathing at negative pressure (BNP, pressure relief by -5.0 cm of water column) during inspiration and expiration was assessed in acute experiments with unconscious cats tilted head-down (-30 degrees). Direct measurement of pressure in v. cava superior and v. jugularis externa using a catheter revealed a concurrent significant (p < 0.05) growth of the parameter which should be considered a sign of impeded venous outflow from the craniocervical vessels. BNP added to the sucking effect of the thoracic cavity (the siphoning effect) and led to more massive venous outflow from cephalic vessels as evidenced by pressure drop in the jugular vein and v. cava superior to the values determined in the basic horizontal position. However, BNP did not significantly alter arterial hemodynamics, respiration pattern or gas exchange. Data of the investigation attest effectiveness of this method of moderating blood flow to the cat's head during HDT and possibility to apply it in the zero-g environment.

Animals↗
PubMedDate not supplied

[Association of polymorphic markers of lipid metabolism genes with diabetic polyneuropathy in type 1 diabetes mellitus].

The aim of this study was the search of association with diabetic polyneuropathy of the polymorphic markers epsilon2/epsilon3/epsilon4 of apolipoprotein E (APOE) and I/D of apolipoprotein B (APOB) genes in groups of type 1 diabetes patients with diabetic polyneuropathy (n = 86) and without its clinical signs (n = 94). We have not found significant association with diabetic polyneuropathy (DPN) of epsilon2/epsilon3/epsilon4 marker of APOE gene. However the comparison of allele and genotype frequencies of I/D marker of APOB gene showed that the carriers of I allele and II genotype had higher risk (OR = 1.66 and 2.01, relatively; p < 0.027), whereas the carriers of D allele had lower risk of DPN (OR = 0.60; p < 0.018). Our findings show that APOB gene, encoding one of the main components of lipid metabolism system, is involved into the diabetic polyneuropathy development in type 1 diabetes mellitus.

Adolescent↗