PubMed Health⌕ Search

Biomedical subjects

I Ramirez

Publications and source records attributed to I Ramirez.

90 records · Page 5Linked to original sources
PubMed1982

Glycerol is not a physiologic signal in the control of food intake in rats.

Rats were given two daily subcutaneous injections of either 40, 80 or 160 mg/kg of glycerol or control injections of glucose. Glycerol injections did not reliably affect body weight gain at any dose tested whether animals were maintained in constant light or a 12 hr light/dark cycle. Only injections of 160 mg/kg of glycerol given twice daily significantly reduced daily food intake; however, this dose also raised plasma glycerol concentrations briefly to an unphysiologic level. Continuous intravenous infusions of 390 or 780 mg/rat/day of glycerol had no effect on food intake, even though plasma glycerol levels increased markedly within the normal range. These findings indicate that reductions of food intake and body weight after administration of glycerol are probably responses to a treatment which is not physiologic.

Animals↗
PubMed1981

Estradiol-induced changes in lipoprotein lipase, eating, and body weight in rats.

Daily injections of 5 micrograms estradiol benzoate (EB) for 1, 2, 3, and 12 days decreased parametrial and retroperitoneal adipose tissue lipoprotein lipase activity in ovariectomized rats. Nearly all of this decrease occurred within the 1st day. In contrast, EB-induced body weight loss and hypophagia were very slight during the 1st day after EB administration and increased substantially over the next 2 days. EB did not affect gastrocnemius muscle lipoprotein lipase activity over the first 3 days, but did decrease muscle lipoprotein lipase activity after 12 days. These changes in adipose and muscle lipoprotein lipase activity suggested that EB-induced redistribution of fuel would be greater after 3 days of treatment than after 12 days of treatment. Tests with two different in vivo triglyceride uptake methods confirmed this suggestion. EB-treated rats were hypertriglyceridemic after 12 days of treatment, but not after 3 days of treatment. Elevated plasma triglycerides were associated with an increased rate of triglyceride entry. These findings are consistent with the hypothesis that EB administration temporarily results in redistribution of triglyceride fuel from adipose tissue to muscle, resulting in a transient decrease in rate of weight gain.

Adipose Tissue↗
PubMed1981

Deficits in pituitary and brain cell nuclear retention of (3H)Estradiol in diabetic rats deprived of insulin: time course and metabolic correlates.

Withdrawal of exogenous insulin for 24 h in ovariectomized, streptozotocin-diabetic rats significantly impairs estradiol uptake in whole homogenate fractions of hypothalamus-preoptic area and pituitary gland. Significant reductions in cell nuclear fractions from the same tissues are seen after 36 h of insulin deprivation. Subsequent reinstatement of insulin treatment does not yield full recovery of estradiol uptake after 24 h of insulin replacement. Fat content of the diet has no effect on brain or pituitary estradiol uptake in diabetic animals deprived of insulin for 36 h. Circulating levels of triglycerides, ketones, glucose, glycerol and free fatty acids were found to predict uptake levels to a significant extent, but no single metabolite is reliably predictive across tissues. These data demonstrate that insulin-dependent changes in brain and pituitary uptake of estradiol in rats are slow to develop, and they support the hypothesis that at least some of the reproductive dysfunctions observed in diabetic rats may be the result of impaired cell nuclear estradiol binding in hypothalamus and pituitary.

Animals↗
PubMed1981

Estrous behavior and pituitary and brain cell nuclear retention of [3H]estradiol in chronically insulin-deficient female rats.

Chronic insulin deficiency, produced by administration of 60 mg/kg streptozotocin, leads to reduced estrous behavior and lower estradiol uptake in both whole homogenate and cell nuclear fractions of hypothalamus-preoptic area and pituitary gland in ovariectomized rats. High dietary fat intake produces an ameliorative effect on both lordosis behavior and estradiol uptake, relative to animals fed a standard, carbohydrate-rich diet. Plasma glucose levels are significantly correlated with estradiol uptake levels in brain and pituitary, and with plasma radioactivity levels. The data support the hypothesis that some of the reproductive dysfunctions manifest in female diabetic rats are the result of alterations in nuclear binding of estradiol by central nervous tissue, and that chronic fuel deprivation may represent an important correlate of disruptions in normal steroid action among diabetics.

Animals↗
PubMed1980

Effect of ascorbic acid in vitro on lymphocyte reactivity to mitogens.

The direct effects of ascorbic acid and dehydroascorbic acid in vitro on human lymphocyte proliferation to phytohemagglutinin (PHA) and concanavalin A (Con A) stimulation were determined. Cells exposed to physiologic and high concentrations of ascorbic acid and dehydroascorbic acid showed poorer tritiated thymidine ([3H]TdR) incorporation than controls without the vitamin. The inhibitory effect was dose-dependent, with the greatest inhibition occurring as the concentration of ascorbic acid and dehydroascorbic acid was increased. At supraoptimal concentrations of PHA and Con A, there was no recovery of the mitogen response, indicating that ascorbic acid did not inhibit the response by competition. Viability studies of cells in culture showed that concentrations of ascorbic acid and dehydroascorbic acid, which consistently inhibited mitogenic stimulation of lymphocytes, were noncytotoxic throughout the culture period. Timed addition of ascorbic acid to PHA-stimulated lymphocytes in culture demonstrated inhibition of [3H]TdR incorporation when ascorbic acid was added as late as 96 hours after initiation of culture. However, the greatest inhibitory effect was observed when ascorbic acid was added at initiation or early in culture. Inhibition was also evident when RNA and protein synthesis were determined. The results suggest that physiologic and high concentrations of ascorbic and dehydroascorbic acid affect early metabolic events in the process of mitogen-stimulated lymphocyte activation.

Ascorbic Acid↗
PubMed1980

T lymphocytes in colostrum and peripheral blood differ in their capacity to form thermostable E-rosettes.

The cellular population of human breast milk collected within 5 days postpartum consists primarily of lipid laden polymorphonuclear leukocytes and macrophages, whereas lymphocytes comprise < 10% of the total cells. A discontinuous density gradient technique was developed to obtain highly enriched (75 +/- 6%) fractions of milk lymphocytes. The majority of milk lymphocytes are T cells as determined by their capacity to form rosettes at 4 degrees C with sheep erythrocytes (E). The lymphocytic origin of the rosetted cells was confirmed by morphologic evaluation of Wright-Giemsa-stained cytocentrifuge slides. A novel finding is that a large proportion of milk T lymphocytes form E-rosettes at 37 degrees C as well as at 4 degrees C. The capacity to form thermostable E-rosettes is not a general property of T lymphocytes in the postpartum period, since peripheral blood T lymphocytes from milk donors form few thermostable E-rosettes. In addition, peripheral blood lymphocytes did not acquire the capacity to form thermostable E-rosettes after density gradient centrifugation nor after incubation with autologous milk. The finding that T lymphocytes in milk form thermostable E-rosettes suggests that milk T lymphocytes may be activated or immature. In either case, these data support the concept that lymphocytes that home to the mammary gland are a select subset of the total lymphocyte population.

Cell Separation↗
PubMed1977

A factor analytic--genetic approach to the relation between obesity and behavior in mice.

Genetically heterogenous mice (N = 377) were reared on either high- or low-fat diets for the first 40 days of life. The mice were cross fostered to permit the separation of genetic and environmental effects in a sibling analysis. A total of 26 measures were taken on these mice, including oxygen consumption, activity, sucrose consumption, body weight changes when bitter or high-fat diets were given as the only food, and various morphological measures. A principal-factor analysis of these measures produced eight factors, most of which appeared to be "instrument" factors rather than general factors. Analyses of variance on the factor scores indicated that genetic influences contributed to five of the factors and sex contributed to three of the factors. However, none of the main effects of diet, gene by environment interactions, or sex by environment interactions were significant. Although obesity and behaviors were correlated, the magnitudes of the correlations were generally small.

Age Factors↗
PubMedDate not supplied

Age-related differences in prevalence and intensity of Trichuris trichiura in sensory impaired children from two schools in Guatemala.

A survey of 102 blind and 218 deaf children in 2 specialized schools in Guatemala revealed distinctly different age-intensity profiles of infection with the intestinal helminth, Trichuris trichiura. In the school for the deaf, intensity (measured as eggs per gram of stool) peaked in the children 7 to 8 years old and dropped to very low average levels in the teenagers. By contrast, in the school for the blind, the intensity of T. trichiura remained low until the early teens. Intensity peaked in the age group 13 to 14 years old, and then decreased in the 15 to 17 years old pupils. Behavioural differences between blind and deaf children, or differences between the schools, may have contributed to this differential pattern of infection.

Adolescent↗
PubMedDate not supplied

Use of thyroxine-binding prealbumin in the nutritional assessment of children with cancer.

The level of thyroxine-binding prealbumin was evaluated in 87 pediatric cancer patients ages 1 through 16 years whose cancer was newly diagnosed but untreated, and 39 children with benign disease or no disease. There was no difference in levels of thyroxine-binding prealbumin between the patients with either malignant or benign disease, nor was there a difference between diagnostic categories. Prealbumin values did correlate with age. When the data were compared, there was a correlation between nutritional status and prealbumin level when the total population (N = 126) was age corrected, but not within the malignant disease group by itself. This confirms data that suggest malnutrition in children with cancer is not a result of protein depletion.

Adolescent↗