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Biomedical subjects

S Trojan

Publications and source records attributed to S Trojan.

At least 127 records · Page 7Linked to original sources
PubMed1987

Effect of prolonged hypobaric hypoxia during postnatal development on myelination of the corpus callosum in rats.

Infant rats, together with the female, were exposed to a simulated altitude of 7,000 m every day from birth to the age of 17 days, excepting the 6th, 7th, 13th and 14th day. Animals were studied on the 18th day, 20 hours after the last exposure to hypoxia. Rats aged 12, 15 and 18 days acted as the controls. The number of myelinated axones of the corpus callosum rose from the 12th to the 18th day; the number in animals exposed to hypoxia did not differ significantly from the number in the 15-day-old controls. Axonal section area likewise increased from the 12th to the 18th day and again the value in animals exposed to hypoxia was no different from section area in 15-day-old animals. The number of myelin lamellae rose from the 12th to the 18th day, but in animals exposed to hypoxia it did not differ significantly from the value found in 12-day-old animals. The thickness of the myelin layer increased from the 12th to the 18th day; in the experimental animals it was the same as in the 12-day-old controls. The myelin lamellae likewise became thicker, between the 12th and the 15th day; in animals exposed to hypoxia this parameter was the same as the value in 12-day-old rats. In the electrophysiological part of the study, the development of the interhemispheric response was analysed. In animals exposed to hypoxia, the individual waves of the IHR had the same shape and latent periods as in 15-day-old animals. The results demonstrate that hypoxia has a profound effect on morphological and functional maturation of the corpus callosum in infant rats.

Aging↗
PubMed1986

Development of aminotransferase activities in the serum of young rats born to normal females and to females exposed to intermittent hypoxia during pregnancy.

In the rat, aspartate aminotransferase (GOT) and alanine aminotransferase (GPT) activity increase during early postnatal ontogenesis. The development of these enzyme activities also remains normal in young whose mothers were repeatedly exposed to altitude hypoxia at a simulated altitude of 5 000 m during the whole of pregnancy.

Alanine Transaminase↗
PubMed1986

The development of hippocampal structure and how it is influenced by hypoxia.

When analysing the function of a neuronal system, it is important to know how the connections of the various neuronal elements are organized. One way in which the structure of nervous tissue can be studied is to become acquainted with the basic principles of its development. This can be achieved by studying the process of normal development, or else by experimental means aimed at inducing changes which help to uncover the laws of the interrelationships of the various elements forming the neuronal system. We studied pyramidal cell structure in the CA1 region of the rat hippocampus during normal postnatal development and after repeated exposure to altitude hypoxia (8 h a day from birth to 17 days at a simulated altitude of 7000 m). At 18 and 90 days the brains of the experimental and control animals were impregnated by the Golgi-Cox method for light microscopy. The brains of 5-, 10-, 15-, 24-, 48- and 90-day-old animals which had developed normally were treated similarly and subjected to a parallel analysis including quantitative methods of electron microscopy. The various parts of the dendritic system are not formed simultaneously. Up to the 15th day, the basal dendrites and the shaft of the apical dendrite, together with its terminal branches, develop. Between the 15th and the 24th day development continues with the proliferation and ramification of the lateral and preterminal branches of the apical dendrite. The number of dendrites is established the first, followed by growth and branching. Development of the dendritic spines involves a change in their shape as well as an increase in their number. From being short and thick the spines develop into structures with a thin neck and a claviform and sometimes branched head. Development of the receptive component of neuronal structure is accompanied by an increase in the number of afferent fibre terminals. Type I synapses are differentiated earlier and in larger numbers than type II synapses. The pyramidal cells of the hippocampus of rats exposed to hypoxia in early life have fewer basal dendrites and fewer terminal fibres on the apical dendrites at 18 days. Hypoxia also leads to lower dendritic spine density and to changes in the shape of the spines reminiscent of less mature forms.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1985

Effects of short-term and prolonged aerogenic hypoxia on gamma-glutamyl transpeptidase activity in the brain, liver, and biological fluids of young rats.

Posthypoxic fluctuations in the levels of two excitatory amino acids, glutamate and aspartate, may be related to changes in mechanism(s) which are responsible for their reuptake. As gamma-glutamyl transpeptidase (GGT) plays a role in mediating the uptake of glutamate and aspartate into various compartments of the brain, we studied changes in the activity of this enzyme in main regions of the brain in young and adult rats. We found a posthypoxic increase in bound GGT activity in some brain regions of 18-day-old animals after acute exposure, but no changes were observed after prolonged altitude hypoxia, with the exception of a decrease in cortical GGT activity. In contrast, acute hypoxia decreased GGT activity in the cortical capillaries to 59%, but prolonged hypoxic exposure was ineffective. However, the activity of soluble GGT in the cerebrospinal fluid of both groups of rats was several-times elevated in comparison with controls. At the same time, bound GGT activity was increased in the liver after acute or prolonged altitude hypoxia. The soluble GGT activity in plasma was only increased after prolonged exposure. Ninety days after prolonged hypoxic exposure the bound GGT activity was reduced in all brain regions to about 60-70% of controls (significantly higher in females than in males) as long-term developmental sequel from early postnatal hypoxia.

Altitude↗
PubMed1985

The hypoxanthine level in cord blood--a potential indicator of foetal hypoxia.

Hypoxia is one of the commonest causes of perinatal morbidity and mortality. The worst affected are tissues with high oxygen consumption, in particular nervous tissue (Trojan 1978). Criteria enabling prompt and reliable evaluation of the length and intensity of hypoxia are therefore being sought (Saugstad 1975a,b, Tuchschmidt et al .1981, O'Connor et al. 1981a,b). In recent years, conflicting information has appeared in the literature on the possibilities of utilizing the hypoxanthine and xanthine level in body fluids as an indicator of oxygen deficiency (Saugstad 1975a, Tuchschmidt et al. 1981). We therefore tested this criterion in newborn infants at risk from intrauterine hypoxia.

Female↗
PubMed1984

Correlation between electrocorticographic and motor phenomena induced by pentamethylenetetrazol during ontogenesis in rats.

Motor and electrocorticographic (ECoG) phenomena induced by pentamethylenetetrazol (PTZ) were directly compared in adult as well as in young rats (age groups of 7, 12, and 18 days). The technique for implantation of cortical electrodes was elaborated in young rats. Myoclonic jerks were elicited by PTZ in all age groups studied. In adult animals they were accompanied by isolated spikes and/or spike-and-wave complexes, whereas in 7-day-old rats there was a poor correlation between ECoG abnormalities and myoclonic jerks. With increasing age an improved correlation between ECoG abnormalities and behavioral changes were noted. After further injections of PTZ, rats had generalized tonic-clonic motor seizures. Ictal ECoG activity usually started in one cortical region in 7-day-old rats and became progressively generalized whereas in older rats generalized electrical discharges accompanied the motor seizures from onset. The clonic phase of motor seizures was not always accompanied by specific ECoG changes in young rats. At all ages the correlation between ECoG activity and individual phases of the generalized tonic-clonic seizures was poor.

Animals↗