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Biomedical subjects

R Villalobos

Publications and source records attributed to R Villalobos.

25 records · Page 2Linked to original sources
PubMed1983

Circadian variations of adenosine level in blood and liver and its possible physiological significance.

The role of adenosine as a possible physiological modulator was explored by measuring its concentration in different tissues during a 24-hour period. Initially the circadian variations of adenosine and other purine compounds such as inosine, hypoxanthine, uric acid and adenine nucleotides were studied in the rat blood. A daily cyclic response was observed, with low levels of adenosine from 08.00 - 20.00 h, followed by an increase from this time on. Inosine and hypoxanthine levels were elevated during the day and low at night. The uric acid changes observed indicate that the decrease in purine catabolism coincides with a decrease in inosine and hypoxanthine levels and an increase in adenosine. The blood adenine nucleotides, energy charge and phosphorylation potential remained constant during the day and showed oscillatory changes during the night. Similar studies were made in the liver, a primary source of circulating purines. Liver adenosine was high during the night while inosine and hypoxanthine remained low along the 24 hours. The results suggest that liver purine metabolism might participate in the maintenance and renewal of the blood purine pool and in the energy state of erythrocytes in vivo.

Adenosine↗
PubMed1983

Calcium uptake during the cell cycle of Saccharomyces cerevisiae.

Synchronous culture of the budding yeast Saccharomyces cerevisiae was obtained by sucrose density gradient selection with 90-100% of yeast synchronized by using the cells in the bottom. In these adult cells bud emergence is coincident with an increase in calcium uptake at 100 min of the culture, followed by a return to basal values which are maintained until the end of the first cell cycle of study. The phenothiazine derivatives, trifluoperazine and chlorpromazine inhibit bud emergence and trifluoperazine also increases calcium uptake.

Biological Transport, Active↗
PubMed1982

The regional distribution of manganese in the normal human brain.

The concentration of manganese per gram dry tissue weight was determined in samples from 39 areas of 8 normal human brains. Manganese was shown to be unevenly distributed with the largest concentrations in the pineal gland and the olfactory bulb. The gray matter yielded a higher content of manganese than the white matter. Significant differences between individuals were found for identical areas of the gray and white matter of the cerebral cortex. Higher levels of manganese were demonstrated in the tail of the caudate nucleus than in the body and the head of the same structure. No significant correlation was shown between the amount of manganese in brain and age.

Adolescent↗
PubMed1977

T-cell deficiency in immune complex glomerulonephritis.

Mice chronically infected with the virus of lymphocytic choriomeningitis (LCM) develop immune complex glomerulonephritis. Others have shown that adoptive immunization of these mice by the i.p. injection of syngeneic immune spleen cells terminates the chronic viral carrier state. The present studies were designed to define the effector cell from the immune spleen responsible for adoptive immunization and to determine the effect of this procedure upon the immune complex nephritis which occurs in LCM carrier mice. The results indicate that the effector cell in adoptive immunization is a T-cell that functions directly as a killer cell when transferred to LCM carrier mice. Sixteen of nineteen adoptively immunized mice examined had less immune complex material deposited in their glomeruli than control unmanipulated litter mates. These data demonstrate that this animal model of immune complex glomerulonephritis is immunodeficient with respect to LCM virus-specific killer T-cells. Transfer of this cell population to the LCM carrier mouse diminishes the animal's viremia and improves its immune complex nephritis. In view of these observations, it is suggested that the rationale for the use of immunosuppressive therapy in spontaneously occurring glomerulonephritis should be carefully reconsidered.

Animals↗
PubMedDate not supplied

[Advances in the diagnosis of epilepsy].

INTRODUCTION. Over the past ten years, evaluation of epilepsy has changed drastically thanks to the development of diagnostic procedures which have transformed understanding of the neurophysiological basis of the development of convulsive seizures. In the USA alone 2 million people are affected by this disease. Of these approximately 20% continued to have seizures in spite of receiving medical treatment. This means that the condition is of a priority for public health attention in any country. Technology used in many areas of diagnosis has allowed the patient with epilepsy to be managed in a much more integrated manner, and therefore to have better possibilities regarding quality of life . DEVELOPMENT. We define these technological advances in three areas in which progress has fortunately been outstanding. Firstly, obtention of better anatomical and functional images permit correlation of the pathology with a specific type of epileptogenic activity. Secondly, understanding the electro clinical semiology resulting from the generation of abnormal cortical activity with subsequent activation of different areas of the cerebral cortex, has made it possible to treat epilepsy surgically. Finally the discovery of genes affecting the presentation of a particular epilepsy syndrome defines the diagnosis and give orientation as to treatment and prognosis in particular cases.

Brain↗