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Biomedical subjects

N A Novikova

Publications and source records attributed to N A Novikova.

At least 19 recordsLinked to original sources
PubMed1993

[Modifications to the solution for reperfusion of the ischemic heart].

Isolated working guinea pig hearts were subjected to 30-min total normothermic ischemia and 30-min reperfusion with modified Krebs solution to which various agents were added. The presence of glutamate in the solution resulted in better recovery of cardiac pump function and higher myocardial energy phosphate levels. Addition of phrelone, a calmodulin inhibitor, or adenosine and ribose did not improve pump function. The similar functional recovery was observed after addition of taurine instead of glutamate and their combination exerted even higher functional recovery while further addition of phosphocreatine was not so effective.

Animals↗
PubMed1992

[The electrophoretic typing of rotaviruses in the clinico-epidemiological study of infection].

The electrophoretic study of the RNA of human rotavirus strains (1146 strains) circulating in 9 cities at the territory of the European part of the RSFSR was carried out. The electrophoretic (EP) types of rotavirus were established in each individual area. The study revealed that the most widespread rotaviruses responsible for the majority of gastroenteritis cases are those with the long EP type of RNA, characterized by the joint migration of segments 2, 3 and 7 (the 3rd EP type of RNA). Rotaviruses with the 3rd EP type of RNA much more often induce a severe course of rotavirus gastroenteritis in children aged 8 months to 3 years.

Acute Disease↗
PubMed1992

[Functional significance of 2 pathways of energy transport in cardiomyocytes].

To study the relative roles of creatine kinase (CK) and adenylate systems in cardiac energy turnover, the effect of CK inhibitor, iodoacetamide- (IAA, 0.5 mM), and 2-deoxyglucose-(DOG, 2 mM) induced) 65% depletion of adenine nucleotides at slightly decreased CK flux was determined in isolated rat heart. Both substances did not substantially affect contractile parameters of the isovolumic heart. However, an augmentation of cardiac work induced by isoproterenol addition was feeble and transient in IAA-treated hearts while the response of DOG-treated hearts was well preserved. The cardiac failure after IAA treatment was associated with irreversible fall in myocardial ATP content as evidenced by 31P-NMR technique. Furthermore, these hearts were unable to perform cardiac pump function due to insufficient cardiac filling and distensibility. The DOG-treated hearts exhibited 50% reduction in the pump function and were able to increase their work in elevated resistance. The results suggest that CK pathway is extremely important for both full cardiac relaxation and maximal contractile function.

Adenosine Triphosphate↗
PubMed1991

[The detection of rotavirus RNA in nasopharyngeal smears by molecular hybridization].

Rotavirus RNA was detected in nasopharyngeal washings, obtained from patients with rotavirus gastroenteritis (76.3% of cases) and gastroenteritis of unknown etiology (34.7% of cases), by the method of molecular hybridization with the use of RNA of monkey virus SA11, labeled with 32P in the process of T4-ligase reaction. In 100% of cases this detection correlated with the presence of lesions of the upper respiratory ways and was probably indicative of the rotavirus nature of the catarrhal syndrome in rotavirus gastroenteritis.

Acute Disease↗
PubMed1990

[Use of the polymerase chain reaction for analysis of rotaviruses. Nucleotide sequence of a gene, coding for the basic neutralizing antigen VR7 of a human rotavirus with a new G-serotype].

A procedure based on polymerase chain reaction use for the detection of rotavirus has been developed. Full length cDNA copy of the VP7 gene coding for the major neutralization glycoprotein of the human rotavirus RK9 with an unusual "wide" electrophoretype is cloned and sequenced. Glycoprotein VP7 of RK9 has a unique amino acid composition in A and C antigenic regions. It shows that strain RK9 represents a new (12) rotavirus serotype.

Amino Acid Sequence↗
PubMed1990

[The synergistic action of glutamic acid and phosphocreatine on the metabolism and function of the heart during ischemia and reperfusion].

The combined effect of glutamic acid (15 mM) and phosphocreatine (10 mM) on metabolism and postischemic recovery of cardiac function was studied in isolated perfused working guinea pig hearts. Addition of these two agents into standard hyperpotassium cardioplegic solution increased twice the recovery of the aortic output and improved restoration of volume work and an index of functional recovery. This effect was combined with the complete recovery of ATP, phosphocreatine, the decrease in ammonia and lactate tissue contents and preservation of amino acid pool. Lesser leakage of creatine and creatine kinase pointed to lesser damage of the sarcolemma. The results show the effectiveness of the use of cardioplegic solution containing both glutamic acid and phosphocreatine.

Animals↗
PubMed1990

[The effect of caffeine on the cardiac diastole and systole in rats and guinea pigs].

The pump function and left ventricular (LV) pressure of isolated rat or guinea pig hearts were measured during caffeine infusion into the perfusate at increasing concentrations (0.1-0.25 mM for rats and 1-5 mM for guinea pigs). Caffeine in low doses produced an increase in heart rate and in higher doses it caused a decrease in cardiac output, systolic pressure and +dP/dt. A delayed relaxation and a rise in minimal diastolic pressure followed by a fall in LV filling pressure area, occurred concomitantly. The alterations of diastolic indices were more obvious than the changes in systolic ones. An elevation of LV diastolic stiffness followed by a decrease in LV filling was associated with a facilitation of LV ejection at equal LV filling pressure area or +dP/dt.

Animals↗
PubMed1989

Adaptation of cardiac contractile function to conditions of chronic energy deficiency.

Left ventricular (LV) contractile function and pump function were depressed in isolated working hearts from rats treated with either guanidinopropionic acid (GPA), an inhibitor of creatine influx, or the anthracycline antibiotic, adriamycin, for 6 and 10 weeks, respectively. In both groups of treated animals myocardial phosphocreatine content was lower than in control hearts, while ATP content was unchanged. Hearts of treated animals exhibited only a minor depression of cardiac output with a submaximal pressure load or during volume overload. However, at maximal pressure load GPA- and adriamycin-treated hearts performed 43% and 37% less pressure-volume work than control hearts. These changes were due both to decreased LV pressure development and diminished cardiac output. LV diastolic stiffness was significantly higher at the submaximal pressure load and the LV filling pressure area, which reflected LV filling, was lower in hearts of both treated groups. The differences in both indices were exaggerated when the maximal pressure load was applied. Limited LV filling due to incomplete myocardial relaxation appeared to represent the underlying cause of cardiac failure when afterload was increased. These results may be explained if adaptation of cardiac contractile function in some chronic cardiac diseases arises from a limited energy supply to the myofibrils.

Adaptation, Physiological↗
PubMed1989

[Electrophoretic analysis of genome RNA of human rotaviruses].

The schemes for profiles of migration of RNA segments from human rotaviruses isolated in Gorky city in 1981-1987 are presented. The groups of the "long", "short" and "wide" electrophoretypes were identified. The dominant rotaviral phoretypes are determined. The possibilities of electrophoretyping and prospects of the future research are discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

The cardiac contractile failure induced by chronic creatine and phosphocreatine deficiency.

Rats were fed a diet containing beta-guanidinopropionic acid (GP), an inhibitor of creatine transport. After 6 to 8 weeks of feeding the myocardial creatine (Cr) and phosphocreatine (PCr) stores were severely depleted while ATP content was normal. Hearts of GP-treated rats perfused according to Neely's working heart model revealed clear cardiac contractile failure: the maximal work capacity at a stepwise increase in resistance as well as the maximal oxygen consumption were 32 to 40% less in the GP group. The cardiac failure in GP-treated working hearts was associated with a rise in the left ventricular diastolic pressure, which could cause a diminished cardiac output probably due to impaired LV filling. The extent of the contractile failure was found to depend on functional load and on the degree of Cr (PCr) substitution. The energy fluxes through creatine kinase measured by the 31P-NMR saturation transfer technique were diminished by a factor of two after substitution of 90% of creatine, but still exceeded the rate of ATP turnover. The results are compatible with the concept of phosphocreatine pathway for intracellular energy transport and show that PCr is an important high energy phosphate compound for cardiac contractile function.

Animals↗
PubMed1988

[Relation of cardiac diastolic elasticity to its adaptation to loading].

The pump function of the isolated rat or guinea pig hearts was assessed at various functional loads. The diastolic left ventricular (LV) stiffness was determined by a ratio of a rise in LV pressure for a diastole to LV filling volume for a diastole. This index was several times lower for guinea pig's hearts as compared to the rat hearts at equal heart rate. It was associated with a higher cardiac output of guinea pig hearts at low left atrium filling pressure. The rat hearts, however, having a higher diastolic stiffness adapted better to increased resistance or elevated heart rate, preserved the cardiac output and markedly increased cardiac work. The data obtained suggest that LV diastolic stiffness is an important factor determining cardiac adaptation to various functional loads; its influence seems to be actualized through changes in the LV filling.

Adaptation, Physiological↗
PubMed1988

[Cardiac relaxation and distensibility in energy deficit].

Changes in the cardiac pump function, contractility, relaxation and distensibility in progressive metabolic blockade induced with dinitrophenol, were compared in the guinea pig isolated heart. A fall in relaxation and distensibility occurred first and was more obvious than a fall in contractility or the cardiac output. The same relationships were observed in isolated hearts of rats with myocardial phosphocreatine deficiency. The fall in relaxation and distensibility seem to be the necessary sign of acute or chronic myocardial energy deficiency.

Animals↗
PubMed1987

The role of phosphocreatine and ATP in contraction of normal and ischemic heart.

The effect of cellular creatine (Cr) and adenine nucleotides (AdN) deficiency on cardiac work, ATP turnover rate and flux through creatine kinase (CK) has been investigated. Depletion of 60-65% of total heart AdN by 2-deoxyglucose treatment in the presence of pyruvate and subsequent washout resulted in only 25% decrease in contractile activity and phosphocreatine level. Substitution of 80-90% of heart Cr (and PCr) by guanidinopropionic acid (GP) by feeding of rats with 1% GP diet reduced maximal values of cardiac work, ATP turnover and flux through CK by 40-50% and elevated end diastolic pressure and index of diastolic stiffness. Hearts depleted of AdN or glycogen showed better post-ischemic recovery of mechanical function that can be attributed to restriction of accumulation of ischemic catabolytes (lactate, H+, Pi). These data imply that in myocardium PCr is an essential high energy phosphate and contractile function stays unchanged at significantly reduced ATP levels.

Adenosine Triphosphate↗
PubMed1987

[Contractile function of the isolated heart in chronic adriamycin-induced myocardial lesions].

Adriamycin, administered to rats for 4 weeks, caused insufficiency of isolated heart contractility with a twofold reduction of cardiac output in surviving animals. The same cumulative dose of adriamycin, administered to rats over 10 weeks, was not associated with any significant reduction of the heart's pumping function. However, heart rate increase by atrial electrostimulation that shortened the diastolic pause to a control level, also reduced the minute and stroke volumes by 38%, as compared to the controls. All animals showed increased diastolic stiffness of the left ventricle that must have interfered with its filling, particularly so in case of low inflow pressure, and disturbed atrial automaticity, as reflected in bradicardia in rats and supraventricular arrhythmia in guinea pigs.

Animals↗
PubMed1986

[Isovolumic and auxovolumic constants of cardiac relaxation in evaluating its inotropism].

The left ventricular pressure curve was registered in experiments on isolated guinea pig heart performing external work. An analysis of initial diastolic portion of the curve in logarithmic scale has revealed for the first time that the time course of the pressure fall is accelerated during transition from isovolumic to auxovolumic phase. The constant of pressure fall rate in auxovolumic phase (ACPFR) has been approximately 1.5-fold higher than isovolumic constant. The former also changed significantly more than the latter one during elevation in Ca2+ perfusate concentration or EGTA addition. A parallel reduction in ACPFR and rate of left ventricular filling during EGTA addition was observed in special experiments with elimination of left atrium distension. Thus, inotropic changes in myocardial relaxation seem to determine left ventricular filling rate.

Animals↗