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T Samorajski

Publications and source records attributed to T Samorajski.

At least 37 records · Page 2Linked to original sources
PubMed1982

Regional mapping of neostriatal neurotransmitter systems as a function of aging.

The purpose of the present investigation was to map chemically the distribution of certain neurotransmitter systems in the neostriatum of rats aged 6, 16, and 26 months. This mapping was carried out by microdissection of discrete striatal regions coupled with radiometric assays for choline acetyltransferase (ChAT), glutamate decarboxylase (GAD), dopamine (DA), and norepinephrine (NA). In all age groups, ChAT, DA, and NA were highest in the rostral relative to the caudal neostriatum. Additionally, ChAT was higher in the lateral than in the medial region, whereas GAD was more homogeneously distributed within the striatum. ChAT activity was decreased significantly primarily in the caudal regions in rats aged 16 and 26 months. DA levels were decreased in the caudal striatum in rats aged 26 months. NA levels were found to be significantly decreased primarily in the rostral neostriatal regions of the oldest rats. GAD activity remained unchanged in all age groups. These regional changes in selected neurotransmitter systems may underlie specific motor and cognitive deficits that often occur during aging.

Aging↗
PubMed1982

Alcoholism in the geriatric population.

Alcohol abuse by elderly persons may be overlooked by clinicians because the effects of alcoholism on intellectual processes may be attributed to advancing age. In older patients, in whom liver and other organ functions may be reduced, even modest social drinking will impair cognitive abilities. Alcoholism is especially detrimental to older persons because 1) their blood levels of ethanol are higher than those in younger persons, and brain neurons may be more sensitive to the drug; 2) ethanol can disturb their sleep and sexual performance; 3) their cognitive functions may be significantly impaired by ethanol; and 4) for elderly patients, who commonly take a variety of drugs, ethanol and drug interactions are particularly hazardous.

Adult↗
PubMed1981

A morphometric comparison of central and peripheral hypomyelination induced by postnatal undernourishment of rats.

Developing Long-Evans rats were undernourished to produce a body-weight deficit of 39% at the age of weaning. Well-nourished litter mates were used as controls. Morphometric analyses were made of pyramidal tracts and posterior tibial nerves of each animal. In measuring pyramidal tract, we observed that axonal circumferences of myelinated fibers were smaller in the undernourished rats and that the number of myelin lamellae per axon appeared reduced by a small amount. The most striking observation in the undernourished rats compared to the controls was that the proportion of myelinated fibers was decreased by 40% at 20 days of age. Axon circumferences of nonmyelinated axons were not measured. Similar decreases were observed in myelinated axon circumference and myelin lamellae of posterior tibial nerves of undernourished rats. Because of sampling problems, we did not attempt to compare the proportion of myelinated and nonmyelinated fibers in posterior tibial nerves of undernourished and well-nourished rats. These morphometric data, particularly the reduction of myelinated fibers, are consistent with biochemical studies of brain hypomyelination in undernourished rats. The data indicate that the mechanism of hypomyelination in nutritionally deprived rats involves a failure of the "trigger" by which myelin-forming cells begin to sheath axons in myelin.

Animals↗
PubMed1980

A metabolism chamber for measuring oxygen consumption in the laboratory rat and mouse.

Details are given for the construction and use of an inexpensive metabolism chamber to measure oxygen consumption in a relatively large group of laboratory rodents in a brief time. Metabolic rates (MR) were measured regularly in male and female Sprague Dawley rats, 11-114 days old, and mice, 100 days old. Adult mice had higher MR than rats of approximately the same age. Female rats and mice had higher MR than males at all times. To demonstrate the versatility of the metabolism chambers adult rats were injected once or for 9 consecutive days with 6-n-propyl-2-thiouracil (PTU) to inhibit thyroid function and reduce MR, or with the carboxymethylcellulose (CMC) vehicle. PTU failed to lower MR in the animals most probably because CMC vehicle tended to increase MR, an effect more prominent in males than females.

Age Factors↗
PubMed1979

Behavioral evidence for supersensitivity after chronic bromocriptine administration.

Behavioral evidence for tolerance and supersensitivity during and after chronic (30 day) administration of bromocriptine (BRC) or bromocriptine + L-dopa in mice was assessed by measuring wheel running (WR) behavior during and after chronic drug administration, and apomorphine- and methylphenidate-(MP-)induced stereotyped gnawing after termination of chronic injections. In both BRC and BRC + L-dopa groups, tolerance developed fairly quickly to the depressing effect of BRC on WR seen on day 1 of drug administration. Mice receiving BRC showed significant increases in WR by week 2 of chronic drug administration, which persisted for at least two days after the termination of chronic injections. During the first week after termination of chronic injections, low doses of both apomorphine and MP induced significantly more stereotyped gnawing in BRC and BRC + L-dopa mice than in the control mice or the mice treated with L-dopa alone. This behavioral evidence for dopaminergic supersensitivity after chronic BRC administration may have relevance for the clinical use of BRC in combination with L-dopa or other dopamine agonists.

Animals↗
PubMed1978

Dihydroergotoxine(Hydergine) and ethanol-induced aging of C57BL/6J male mice.

The residual effects of dihydroergotoxine (Hydergine), ethanol, and Hydergine-plus-ethanol were investigated in old male mice of the C57BL/6J strain. Prolonged 10% v/v ethanol, concomitant with adequate nutrition, produced a significant decrease in life-span, decreased spontaneous locomotor activity and reduced lipofuscin accumulation in neurons of the reticularis gigantocellularis. These effects were not apparent in mice treated with Hydergine or alcohol combined with Hydergine.

Aging↗
PubMed1978

Dihydroergotoxine and ethanol: physiological and neurochemical variables in male mice.

The residual effects of dihydroergotoxine mesylate (DHET: active substance of Hydergine), ethanol, and DHET + ethanol were investigated in aging male mice. Prolonged alcohol or DHET consumption was found to prolong hexobarbital sleeping time and increase oxygen consumption. Administration of alcohol combined with DHET inhibited the ability of each drug to prolong hexobarbital sleeping time and increase oxygen consumption. There were no significant differences between groups in forebrain synaptosomal (Na+-K+) adenosine- triphosphatase and acetylcholinesterase activity or cerebellar protein, DNA and RNA content. The relative proportion of phospholipid to protein in isolated myelin of the medulla was significantly reduced, whereas the sphingomyelin content of total phospholipid was highest in alcohol-treated mice. Conocomitant treatment of mice with alcohol combined with DHET prevented the physiological and neurochemical changes caused by alcohol and, in some cases, DHET, administered alone.

Acetylcholinesterase↗
PubMed1978

Effects of ethanol and dihydroergotoxine on mouse brain myelin components.

The effects of prolonged consumption of ethanol, dihydroergotoxine (Hydergine) and Hydergine-plus-ethanol on brain myelin components isolated from the medulla oblongata of mouse brain were examined. Based on protein content, the amount of myelin isolated from the brain tissue was not different with regard to the various treatments. However, there was a significant decrease (20%) in myelin phospholipid and cholesterol to protein ratios in the ethanol group as compared to controls and the Hydergine-treated group. On the contrary, the Hydergine and Hydergine-ethanol groups had higher cholesterol to phospholipid ratios than controls. In spite of the changes in membrane components, little change in acyl group composition of the phosphoglycerides was found in myelin.

Aging↗
PubMed1977

Central neurotransmitter substances and aging: a review.

Available evidence suggests that age is an important determinant of the levels of neurotransmitters and their associated enzymes and metabolites in some regions of the brain. Alterations at the synaptic level, or selective cell death in the brain, or both, may be implicated in progressive loss of function, behavioral changes and the onset of age-related diseases. Stimulation of hypothalamic neuroendocrine transducer cells by agents that alter neurotransmitter metabolism might provide some measure of control of the process of aging.

Acetylcholine↗
PubMed1976

How the human brain responds to aging.

The characteristic morphologic changes frequently observed in the brain of an old adult include a decrease in weight and volume, a change in the pattern of cerebral cortical convolutions, and an increase in ventricular size. Cell loss varies from region to region in the brain, and may be intensified in Alzheimer's disease and other disorders associated with senile dementia. Among the neuroglial cells, the microglia undergo the most significant changes with age. Although senile brain disease previously has been regarded as secondary to atherosclerosis, recent neuropathologic studies indicate that only 30 to 40 percent of senile brain disease arises from cerebrovascular pathologic lesions. The dilemma remains, however, of how much of the deterioration observed in the aged is related to disease and how much to senescence. The interaction between gene expression and environmental conditions in aging is another important question for the geriatrician. Progress in the control and treatment of disorders associated with old age depends upon further research into the mechanisms that underlie the process of aging in the brain.

Adolescent↗
PubMed1975

Late ultrastructural changes in neuronal mitochondria after lonizing radiation of the brain.

Brain tissue was examined for morphological changes at 12 and 16 months after focal irradiation of the brain in female mice. Irradiation was performed with deuteron beams derived from the 60-inch Brookhaven cyclotron at a rate of 1925 rad second -minus 1 though an anti-Bragg device which produced uniform exposure. Experimental animals received a dose of 10,000 rad, covering a 9 by 5 mm area over the skull and extending into the brain from a depth of about 2 mm. An additional group of animals served as sham-irradiated controls. Histological studies revealed extensive cell loss, vacuolation, and prominent vascular changes in irradiated regions of the brain at 16 months post-irradiation. Ultrastructural examination of brain tissue at 12 and 16 months after irradiation revealed the presence of unusual elongated mitochondria with parallel arrays of cristae. Altered mitochondria were more prevalent at the longer post-irradiation interval.

Age Factors↗
PubMed1975

Nerve fiber hypertrophy in posterior tibial nerves of mice in response to voluntary running activity during aging.

Three-month-old male C57BL/10 mice were exercised by voluntary running activity in vertically revolving wheels for two hours each day until 24 months of age. Activity scores were recorded each day and the animals were regularly weighed and inspected for abnormalities. Control animals were similarly treated except that the activity wheels were immobilized. At the end of the exercise period, survival was 84% for the exercise group and 64% for the controls. Light microscopic examination of the posterior tibial nerve of the surviving animals showed a significant fiber hypertrophy in response to the exercise. The number of myelinated fibers in nerves from exercised animals did not differ from those of the controls. On the basis of these data, it is suggested that prolonged exercise does not prevent the loss of peripheral nerve fibers associated with age but rather, may exert an effect on the nervous system by modifying the surviving cells.

Aging↗