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Biomedical subjects

T Smirnova

Publications and source records attributed to T Smirnova.

At least 19 recordsLinked to original sources
PubMed2002

Caries experience and treatment response among groups of Finnish, German and Russian children. A retrospective study between 1995 and 1989.

AIM: This study was designed to describe caries experience and treatment response in groups of children in three countries--Finland, Germany and Russia--with different systems of public dental care. MATERIALS AND METHODS: Information concerning permanent teeth (carious and filled surfaces, type of restorative treatment and applied sealants) was collected retrospectively from existing dental records of 12-year-old children who had been treated in dental practices over six years, retrospectively between 1995 and 1989. Prior to conducting the study, research meetings were held among all participating personnel to standardise data collection and terminology as much as possible. STATISTICS: The analysis of variance (ANOVA) was used to test the difference between the means of the various types of data derived from the three countries. RESULTS: Sealants were most commonly used in Finland at a rate of 5.0/child and 3.3 in Germany, but only for a few children in Russia (0.1). Caries increments (cumulative figure of primary and secondary caries surfaces over the six follow-up years of the study) differed very much between these countries. It was very high in Russia (7.4) and in Germany (5.3), but low in Finland (1.6). All the caries surfaces were filled in Finland and in Germany; in Russia, the cumulated number of filled surfaces was smaller than the respective number of caries surfaces (6.4/7.4). The most commonly used restorative filling material was amalgam in Germany and in Russia, but composite or glass ionomer cements in Finland. CONCLUSION: The cost effectiveness of sealant application programs should be considered as exemplified by the Finnish dental care system. The data showed a need for preventive programs in Germany, and this has actually been emphasised since 1993. In Russia, there is an urgent need to implement preventive programs for 6-year-old children and also to provide the necessary restorative treatment.

Journal Article↗
PubMed2000

Differential expression of small heat shock protein 27 in the rat hippocampus and septum after fimbria-fornix lesion.

mRNA, Western analysis and immunohistochemistry were used to study the expression of the small heat shock protein (HSP) 27 in the rat septum and hippocampus following fimbria-fornix lesions, a model of neurodegeneration and regeneration. (HSP) 27 mRNA level was increased 2.5-fold in the medial septum 3 days after lesion and this increase persisted for 10 days. In the hippocampus, after an initial 15-fold increase at 3 days post-injury, HSP27 mRNA returned to basal levels 10 days after the lesion. Three and 10 days after lesion, HSP27 protein levels were increased in the septum (4.5 and 5-fold, respectively) and hippocampus (65 and 10-fold, respectively). The morphology of the HSP27 positive cells was indistinguishable from that of GFAP-immunoreactive cells. In addition, in the septum of injured rats, occasional neurons were heavily labelled with anti-HSP27 antibodies. Thus, up-regulation of HSP27, particularly in glial cells, may be a component of glial input in the processes on degeneration/regeneration which occur in this model.

Animals↗
PubMed2000

Up-regulation of genes involved in cellular stress and apoptosis in a rat model of hippocampal degeneration.

Changes in gene expression within the hippocampus induced by denervation after electrolytic fimbria-fornix lesion in rat were compared to morphological and biochemical alterations. Fimbria-fornix lesion results in degeneration of hippocampal cholinergic terminals as evidenced by a sustained (2 days to 1 month) decrease in cholineacetyltransferase (ChAT) activity (50%). These changes were accompanied by a decrease in growth associated protein 43 (GAP-43) immunoreactivity in all hippocampal layers 4 days after lesion followed by a subsequent increase and return to normal levels by 20 days postinjury. This increase in GAP-43 expression in the hippocampus between 7 to 20 days after lesion may reflect heterotypic sprouting. TUNEL-positive cells were revealed by in situ assay within the hippocampus at 10 days, but not at 3 days, after lesion. Two subtracted cDNA libraries from the dorsal hippocampus of control and injured rats (at 3 and 10 days postlesion) were constructed in order to search for new genes potentially implicated in degeneration/regeneration phenomena. We analysed 1,536 clones from each library by differential screening and found a total of 46 up-regulated genes. Among the 15 known genes, 6 coded for proteins involved in signal transduction pathways. The upregulation of growth arrest DNA damage induced gene (GADD153), brain-specific RING finger protein, JNK interacting protein (JIP-1), protein kinase A (PKA), and Na+K+ ATPase was studied by quantitative polymerase chain reaction (PCR). Two of these genes, GADD153 and JIP-1, have been previously shown to participate in cell modifications induced by stress and apoptosis.

Animals↗
PubMed1998

Exercise-induced hormone responses in girls at different stages of sexual maturation.

The dependence of exercise-induced hormone responses on sexual maturation was tested in a 3-year longitudinal experiment on 34 girls (aged 11-12 years at the beginning). Sexual maturation was evaluated by Tanners five-stage scale. Children cycled for 20-min at 60% maximal oxygen uptake once a year. Cortisol, insulin, growth hormone, beta-oestradiol, progesterone and testosterone concentrations in venous blood were determined by radioimmunoassay procedures. Basal concentrations of growth hormone increased and of cortisol decreased when breast stage III was reached. Reaching breast stage IV was associated with an increase in basal concentrations of beta-oestradiol, progesterone and testosterone. The exercise induced significant increases in concentrations of cortisol, growth hormone and beta-oestradiol and a decrease in insulin concentration. At breast stage III the increase in cortisol concentration was to a lower level [467 (SEM 42) vs 567 (SEM 46)nmol x l(-1)] and growth hormone concentration to a higher level [29.4 (SEM 0.5) vs 12.8 (SEM 0.4)ng x ml(-1)], while the fall in insulin concentration was less pronounced [postexercise level 10.6 (SEM 0.9) vs 7.8 (SEM 0.8)mU x l(-1)] than in stage II. The magnitude of the cortisol response was reduced in the last stage of breast development (+42.1% vs +55.5% at stage II, +66.2% at stage III, and +50.0% at stage IV). The magnitude of beta-oestradiol response was the lowest in breast stage IV (+15.8%) and the highest at stage V (+41.1%). The progesterone response became significant at stage IV and testosterone response at stage V. In conclusion, we found that reaching breast stage III was associated with altered responses of cortisol, insulin and growth hormone concentrations while the responses of the sex hormone concentrations became pronounced in the last stages of sexual maturation.

Adolescent↗
PubMed1998

Effect of creatine supplementation during rapid body mass reduction on metabolism and isokinetic muscle performance capacity.

Well-trained subjects (n = 6) were studied before and after losing a mean 3.0%-4.3% of body mass to determine whether muscle performance could be maintained or even enhanced by dietary creatine supplementation. During a 5-day period of loss of mass the subjects were randomly assigned to a creatine or placebo supplemented diet. All the subjects were measured before and after loss of mass on both supplements for isokinetic peak torque (PT) and work at peak torque (W(PT)) of knee extensors, also for intermittent high intensity working capacity of the same muscle group. The latter test consisted of submaximal isokinetic knee extensions at an angular velocity of 1.57 rad x s(-1) for 45 s at the rate of 30 contractions each min (submaximal work, Ws max) followed by 15-s maximal effort (maximal work, Wmax). Total duration of the test was 3 min. Haematocrit was measured and haemoglobin, ammonia, lactate, glucose and urea concentrations were analysed in blood samples obtained at rest and after cessation of muscle performance tests. The results indicated that creatine supplementation in comparison with placebo treatment during rapid body mass reduction may help to maintain muscle PT and W(PT)1 at high angular velocities, not influencing Wmax and the rate of fatigue development during Wmax, but affecting adversely Ws max. Within the limitations of the present study the reasons for the partially detrimental effect of creatine administration remain obscure, but it is suggested that impaired creatine uptake in muscle during body mass loss as well as creatine induced changes in muscle glucose and glycogen metabolism may be involved.

Adult↗
PubMed1998

Hormonal responses to exercise in girls during sexual maturation.

The dependence of hormonal responses to exercise on sexual maturation was tested in three-year longitudinal experiment on 34 girls (11-12 years old at the beginning of the study). Sexual maturation of the girls was evaluated using Tanner scale. Girls were divided into three groups: maturation stages 1-2, 2-4 and 4-5. Children performed a 20-min cycle exercise at 60% of maximal oxygen uptake (VO max) once a year. Cortisol, insulin, somatotropin, beta-estradiol, progesterone and testosterone were determined in venous blood by RIA procedures. High basal levels of beta-estradiol and somatotropin appeared in stages 2-4 (387 +/- 92 pmol.l-1) and 12.9 +/- 2.85 ng.ml-1, respectively) and 4-5 (358 +/- 54 pmol.l-1) and 14.3 +/- 1.53 ng.ml-1, respectively). The basal progesterone level increased with maturation, testosterone appeared in the blood in stages 2-4 and 4-5. The exercise resulted in increased levels of cortisol and somatotropin, and a drop in insulin in all girls. The cortisol response was most pronounced in stage 1-2. Postexercise insulin concentration was the highest in stage 4-5. beta-estradiol level increased by 23% in stages 1-2 and 4-5, while the response was insignificant in stages 2-4. Exercise-induced progesterone increase was significant in stage 4-5. In conclusion, sexual maturation associates with several quantitative changes in exercise-induced hormonal responses.

Child↗
PubMed1996

Effect of rapid weight loss on metabolism and isokinetic performance capacity. A case study of two well trained wrestlers.

The effect of rapid weight loss on metabolism and isokinetic performance of quadriceps femoris muscle in two well-trained wrestlers was investigated. Weight reduction by 5.1-5.8% during 3 days resulted in reduction of plasma volume by 7.4-14.8% and increase in blood urea concentration by 1.8-2.1 times. Blood lactate response to standardized 5-min isokinetic performance test exercise was not dependent on body weight status. Peak torque, time to peak torque, rate of peak torque development and maximal power output measured during single maximal contraction of the quadriceps femoris muscle, as well as muscle working ability measured during 5-min isokinetic performance test were all impaired as a result of weight reduction. Body weight of the subjects, plasma volume, blood urea concentration and muscle isokinetic performance characteristics did not return to the initial levels even after 16.5-hrs recovery period (with food and drink ad libitum) following weight loss. These findings suggest that rapid weight loss by ca 5-6% may interfere wrestlers' metabolism and impair the quadriceps femoris muscle function. Moreover, 16.5-hrs recovery period with food and drink loading may be not sufficient to eliminate the negative consequences of body weight manipulation.

Adult↗
PubMed1995

A syntaxin-related protein controls acetylcholine release by different mechanisms in Aplysia.

Polyclonal antibodies raised against rat syntaxin-1B and an affinity-purified fraction have been used to study the functional role of this protein in transmitter release from Aplysia neurons. In a ganglionic protein extract, this fraction recognized a 37,000 molecular weight protein which therefore might be the Aplysia homologue of rat brain syntaxin-1B. Immunoglobulins were injected in the presynaptic cell of an identified cholinergic synapse of the buccal ganglion of Aplysia californica. This treatment decreased the postsynaptic response due to a reduction of the number of quanta released in relation to a decline of presynaptic Ca2+ current. When antibodies were applied extracellularly, transmitter release also decreased. In contrast to intracellular injection, this reduction was not accompanied by a decrease of the Ca2+ current but by an increase of presynaptic outward current. When injected in the presynaptic neuron, syntaxin complementary RNA also depressed Ca2+ current and transmission. This work provides evidence that Aplysia neurons express a syntaxin-like protein which is involved in the control of the presynaptic Ca2+ influx triggering acetylcholine release from terminals. This protein appears to have an extracellular segment which might interact with outward current.

Acetylcholine↗
PubMed1995

The expression of syntaxin1B/GR33 mRNA is enhanced in the hippocampal kindling model of epileptogenesis.

Syntaxin, a protein required for the docking of synaptic vesicles, may be involved in the manifestation of synaptic plasticity. The possible involvement of syntaxin in epileptogenesis was investigated by assessing the expression levels of syntaxin1B/GR33 mRNA by in situ hybridization at different stages of hippocampal kindling epileptogenesis and after the induction of generalized seizures. Densitometric analysis of the autoradiograms revealed that the expression was not changed in pyramidal and granular neurons of the hippocampal formation 24 h after the first kindling stimulation. However, the mRNA levels in CA1, CA3, and fascia dentata neurons were bilaterally enhanced after six afterdischarges and remained at this elevated level during the whole period along which afterdischarges were elicited. An immunoassay was unable to reveal a clear significant increase of syntaxin1B/GR33 protein levels in hippocampus homogenates of fully kindled animals. The use of syntaxin1B-specific antibodies is necessary to draw definite conclusions on the changes at the protein level. At long term, 4 weeks after the last kindling-elicited generalized seizure, no significant alterations in transcript levels could be detected. The results suggest that the induction of kindling epileptogenesis is associated with an enhanced expression of syntaxin1B/GR33, but this enhanced expression is not necessary for persistence of kindling-induced synaptic plasticity.

Animals↗
PubMed1995

Health promotion and exercise training.

Health is determined not only by the absence of disease, but also by an individual's resistance to pathogenic factors. In turn, resistance depends on the effectiveness of specific homeostatic regulation and the mechanism of general adaptation. Through the change in adaptivity, health may be increased or reduced. While it is difficult to predict which specific homeostatic mechanism will be necessary in various stages of life in the individual, it is more reliable to try to improve health, thereby increasing the effectiveness of the mechanism of general adaptation. Physical training results in a variety of changes in individuals. There are several changes which are essential both for increased exercise performance and for increasing adaptivity, by favouring the effectiveness of the mechanism of general adaptation. These changes: improve central nervous regulation and central nervous system functions; increase endocrine system capacity; increase energy potential; improve the capacity of the oxygen transport system; improve oxidation processes; increase metabolic and functional economy; increase functional stability; and increase the number of Na+,K+ -pumps. The influence of these changes on adaptivity is accomplished by the influence of exercise training on immunoactivities, and by the antisclerotic effect of training. The latter may be considered to be metabolic (actualised through the training effect on lipoprotein metabolism and aging-related calcium distribution) or mechanical (protection of tissues from sclerotic changes by their activities) effects. The training effects are specifically dependent upon performed exercises. Endurance exercise is considered to be the most important and widely recommended form of exercise for health improvement. Most of the training benefits (listed above) for increased adaptivity are induced by aerobic endurance training. Gymnastic exercises are indispensable in regard to mechanical antisclerotic effect. They are also essential influences on the central nervous system. Aerobic dance or aerobic rhythmic gymnastics are ways by which the positive effects of endurance and gymnastic exercise can be combined.

Adaptation, Physiological↗
PubMed1994

Glucocorticoids in metabolic control during exercise: alanine metabolism.

To evaluate glucocorticoid participation in the control of alanine metabolism during exercise, experiments were performed on adrenalectomized and normal male rats. The adrenal insufficiency prevented the rises induced by 3 h of swimming in alanine levels of blood plasma, red portion of quadriceps, and liver. In normal rats, the rise in alanine content by 65% in blood, 50% in fast-twitch oxidative fibers, and 93% in liver was associated with increased activity of alanine aminotransferase in fast-twitch oxidative-glycolytic fibers (by 23%). In adrenalectomized rats, enzyme activity during exercise did not change in muscles and decreased in hepatic tissue (by 25%). The dependence of exercise-induced changes in alanine aminotransferase activity on glucocorticoids was confirmed by an increased enzyme activity (by 53%) in exercised adrenalectomized rats treated with 125 micrograms corticosterone. In normal rats, training prevented both the rise of blood corticosterone and the activation of hepatic alanine aminotransferase during exercise. The results support the view that the stimulation of the glucose-alanine cycle by glucocorticoids promotes alanine supply and utilization in liver during exercise. In adrenalectomized rats, hepatic arginase activity was decreased during exercise and no elevation of urea levels was found in blood, liver, or skeletal muscles. Consequently, the use of products of the deamination of alanine (and other amino acids) for urea formation also depends on glucocorticoids.

Adrenalectomy↗
PubMed1994

Glucocorticoids in metabolic control during exercise: glycogen metabolism.

In order to evaluate the participation of glucocorticoids in the control of glycogen metabolism during exercise, experiments were performed on male adrenalectomized and normal rats. In adrenalectomized rats swimming for 4 hours induced less pronounced increases in lactate concentrations in skeletal muscles than in normal rats (in FG fibers up to 10.7 +/- 1.0 vs 14.8 +/- 1.2 and in SO fibers up to 9.1 +/- 0.7 vs 12.5 +/- 0.7 mg x g-1 wet tissue). The glycogen drop in liver and oxidative muscles was also less pronounced (in liver by 14% vs 52%, in SO fibers by 33% vs 54% in normal rats). Swimming until exhaustion led to an extremely low glucose level in blood (1.89 +/- 0.12 mMol x L-1) in adrenalectomized rats. When they were treated with dexamethasone, the swimming duration was longer (12 +/- 1 hours vs 9 +/- 0.8 hours in saline treated), blood glucose level at exhaustion was higher (3.07 +/- 0.23 mMol x L-1) and the drop of hepatic and muscle glycogen was more pronounced. In normal rats hepatic glycogen content dropped by 68% after swimming for 4 hours. After swimming for 8 or 12 hours further decreases in hepatic glycogen content were insignificant. High levels of corticosterone in blood was found after swimming for 4 and 8 hours. After swimming for 16 hours corticosterone concentration was below normal and a new drop in liver glycogen (until a level constituting only 11% initial) was recorded. The results support the suggestion that glucocorticoids, regulate hepatic glycogen and peripheral glucose utilization during exercise, and also participate in the control of glycogenolysis in muscles.

Adrenal Glands↗
PubMed1993

Characterization of a presynaptic glutamate receptor.

Glutamate receptors mediate excitatory neurotransmission in the brain and are important in the formation of memory and in some neurodegenerative disorders. A complementary DNA clone that encoded a 33-kilodalton protein (GR33) was obtained by screening a library with an antibody generated against glutamate binding proteins. The sequence of GR33 is identical to that of the recently reported presynaptic protein syntaxin. When GR33 was expressed in Xenopus oocytes, it formed glutamate-activated ion channels that are pharmacologically similar to those of N-methyl-D-aspartate receptors but with different electrophysiological properties. Mutation of the leucine 278 residue in the single putative transmembrane segment of GR33 affects the properties of the channel. Thus, in vivo GR33 may be a presynaptic glutamate receptor.

Animals↗
PubMed1993

Transsynaptic expression of a presynaptic glutamate receptor during hippocampal long-term potentiation.

Repetitive activation of excitatory synapses in the hippocampus produces a persistent enhancement of synaptic efficiency known as long-term potentiation (LTP). In anesthetized and in freely moving rats, the induction of LTP in the perforant path led to a transient increase in the amount of messenger RNA (mRNA) coding for a presynaptic glutamate receptor (GR33) in dentate granule cells. The amount of GR33 mRNA was increased for at least 5 hours after the induction of LTP but was indistinguishable from control values 1 day after induction. The N-methyl-D-aspartate receptor antagonist 2-aminophosphonovalerate prevented the induction of both LTP and the increase in GR33 mRNA. The amount of GR33 protein was increased in the mossy fiber terminal zone of dentate granule cells 5 hours after the induction of LTP. These results suggest that the induction of LTP in synapses at one stage in a neural network may lead to modification in synaptic function at the next stage in the network.

2-Amino-5-phosphonovalerate↗
PubMed1992

Stability and variability in hormonal responses to prolonged exercise.

To study the dynamics of alterations in blood hormones and their individual variability during prolonged exercise, changes in plasma levels of corticotropin, cortisol, aldosterone, testosterone, progesterone, somatotropin, insulin and C-peptide were recorded in 32 endurance athletes and 50 untrained persons during a 2-hour exercise on a cycle ergometer at 60% VO2max. Common changes were activation of the pituitary corticotropin function, mostly at the end of exercise, rises in aldosterone and somatotropin concentrations and decreases in insulin and C-peptide levels during exercise. The activation of pituitary-adrenocortical system and the decrease of insulin but not C-peptide levels were more pronounced in athletes than in untrained persons. A large inter-individual variability existed in changes of cortisol, testosterone and progesterone in both groups. Five variants were found in the dynamics of cortisol concentration. Whereas the alterations of corticotropin were characterized mainly by a biphasic increase, the dynamics of corticotropin and cortisol coincided only in one variant out of five. Most characteristic for the postexercise recovery period were decreased activity of the pituitary-adrenocortical system and delayed normalization of aldosterone level.

Adolescent↗
PubMed1991

[Anaerobic "all-out" stress tests: selection of the type and duration of stress].

In the diagnosis of prerequisite conditions for short-term highly intensive activity, performed under conditions of oxygen deficit anaerobic loading tests are used. Contrary to tests of constant performance, "all-out" tests follow up changes of performance in the course of time, i. e. they record the maximal anaerobic performance as well as the decline of performance in the course of the test. In a group of 17 subjects three types of loads were compared (bicycle ergometry, a test repeated jumps and running) and two periods of anaerobic tests--45 s and 120 s. The results achieved in different tests--total work, maximum performance, decline of performance, post-load lactate concentration in blood--differed depending on the type of load and duration of the test. Correlation analysis did not reveal a close relationship between the results of different anaerobic tests, there was however a relationship between the maximum performance and the total work at the level of general physical fitness. The longer variant of the test--120 s--did not prove more suitable, neither from the aspect of the assumed markedly higher lactate cumulation in blood nor from the aspect of maximum performance, as compared with the 45 s test. A close relationship was revealed between the results of the 45 s and 120 s jumping and running test but not between the results of bicycle ergometry. The post-load lactate concentration cannot be considered a highly reliable indicator of the level of the anaerobic energy metabolism in the working muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

The effect of a single-circuit weight-training session on the blood biochemistry of untrained university students.

The metabolic and hormonal responses to an intensive single-circuit weight-training session were studied in 15 untrained male students. The training programme consisted of ten exercises, employing all the large groups of muscles. Students performed three circuits using a work-to-rest ratio of 30 s:30 s at 70% of one-repetition maximum. The whole programme lasted 30 min. Blood samples were obtained from the anticubital vein 30 min before exercise, immediately after exercise finished and after 1-h, 6-h, and 24-h periods of recovery. The training session produced significant increases in the plasma adrenocorticotropic hormone, cortisol, aldosterone, testosterone, progesterone and somatotropin concentrations. The plasma level of insulin and C-peptide remained unchanged. The strength exercises caused elevated ratios of cortisol:testosterone and cortisol:insulin, indicating a prevalence of stimulation of catabolic processes as well as of mobilization of energy reserves but during the recovery period the reverse of this was observed. Immediately after exercise the mean lactate concentration was 7.19 mmol.l-1, SD 0.56, the glucose concentration increased significantly during exercise and decreased rapidly during recovery. The high density lipoprotein-cholesterol increased in 1-h period of recovery compared with the initial level. The concentration of total cholesterol, low density lipoprotein-cholesterol and triglyceride, did not change. Packed cell volume did not change during exercise or recovery.

Adrenocorticotropic Hormone↗