Biomedical subjects

S E Calvano

Publications and source records attributed to S E Calvano.

61 records · Page 4Linked to original sources

PubMed1982

In vitro assessment of immune function in adrenalectomized rats.

Spleen and lymph node cells from normal or adrenalectomized (Adx) rats were assessed for a variety of in vitro immunological measures, including mitogen responsiveness, antibody-dependent cellular cytotoxicity (ADCC), and natural killer (NK) cell activity. Proliferation in response to mitogens was evaluated with or without 2-mercaptoethanol (2-ME) in the culture media. Compared to spleen cells from normal rats, those from Adx rats demonstrated enhanced responsiveness to all mitogens tested. 2-ME increased proliferation of spleen cells from both normal and Adx rats, and the effect was additive to that of adrenalectomy. In contrast, lymph node cells from Adx rats manifested decreased mitogenic responsiveness compared to those of control rats and, with the addition of 2-ME, this difference disappeared for one of the mitogens tested (phytohemagglutinin). Compared to unoperated rats, ADCC and NK activities were significantly decreased in both the spleen and lymph nodes of the Adx rats. Alteration of normal leukocyte circulatory and homing patterns are suggested as a likely means by which adrenalectomy produces differential effects on lymphoid cells in various organs of the immune system.

Adrenal Cortex Hormones↗

PubMed1982

Increased heat loss in ovariectomized hypothyroid rats treated with estradiol.

The role of the thyroid in the mediation of an estrogen-associated change in thermal balance was studied in thyroidectomized and in propylthiouracil-treated ovariectomized rats. Prior to propylthiouracil treatment, estrogen-treated ovariectomized rats and intact female rats had higher rates of heat production and dry heat loss at -5 degrees C than ovariectomized rats. Heat production of estrogen-treated and intact female rats was well below their rates of dry heat loss without an alteration in the absolute rate of heat loss in the hypothyroid condition. Heat production exceeded heat loss only in the hypothyroid ovariectomized group not receiving estrogen. Ovariectomized rats without estrogen maintained thermal balance, whereas rectal temperatures fell in both intact and estrogen-treated ovariectomized rats during cold exposure. Increased heat loss unbalanced by heat production was also observed in surgically thyroidectomized estrogen-treated ovariectomized rats tested at -5 degrees C. These results suggest that an estrogen-induced increase in heat loss, which is compensated by an increase in heat production in the euthyroid but not the hypothyroid condition, is one mechanism responsible for estrogen-associated changes in thermal balance during cold exposure.

Animals↗

PubMed1981

Correlation between plasma thyroxine levels and corticosterone-binding activity in intact, ovariectomized, and ovariectomized estrogen-treated rats.

Plasma levels of total thyroxine (T4) and corticosteroid-binding activity (CBA) were determined in intact, ovariectomized, or ovariectomized, estrogen-treated rats during treatment with propylthiouracil (PTU) and following recovery from PTU. Propylthiouracil treatment reduced the mean plasma T4 concentration to 9 ng/ml and the mean plasma CBA to 39% of normal, while following recovery from PTU, the mean values for plasma T4 and CBA were 56 ng/ml and 108%, respectively. There was a strong (r equals plus +0.89) relationship between plasma levels of T4 and CBA as determined by linear regression analysis. Ovariectomy had no effect on either plasma T4 or CBA in euthyroid animals but significantly decreased CBA in PTU-treated, hypothyroid animals. The results indicate a robust influence of thyroid activity on plasma CBA and suggest a possible interaction between the thyroid and ovary in control of CBA.

Animals↗

PubMed1980

Comparison of plasma corticosterone- and progesterone-binding activity in rat and human.

Corticosterone-and progesterone-binding activity were measured by saturation analysis, with dextran-charcoal separation, in plasma obtained from male and female rats, and a normal male and female human. In plasma from normal male and female rats, progesterone was much less effective than corticosterone in displacing 3H-corticosterone from plasma protein binding sites although the parallelism of the displacement curves indicated competition for the same binding sites. In plasma from the normal male human, corticosterone and progesterone were equally effective in displacing 3H-corticosterone. However, 3H-progesterone showed no apparent binding to either rat or human plasma proteins, suggesting that dextran-charcoal effectively removed progesterone from transcortin binding sites at 4 degrees C. This observation was confirmed by multiple equilibrium dialysis. In dialysis, 3H-corticosterone and 3H-progesterone were bound equally by human plasma, but rat plasma bound 3H-corticosterone to a much greater extent than it did 3H-progesterone. These data indicate that, in contrast to human plasma, rat plasma has much greater affinity for corticosterone than for progesterone.

Adult↗

PubMedDate not supplied

Beneficial effect of enteral glycine in intestinal ischemia/reperfusion injury.

It has been shown in vitro that glycine can protect renal tubules and hepatocytes from hypoxic injury. Glycine also attenuates ischemic injury in transplanted livers. The present study investigated the effect of enteral glycine in a murine model of ischemia/reperfusion injury of the small intestine. Mice (n = 12 in each group) were randomized to receive two gastric gavages of either a 20% glycine (Gly) or 23% balanced amino acid (AA) solution with a 6-hour interval between each gavage. One hour after the second gavage, mice underwent superior mesenteric artery clamping for 20 minutes. The clamp was then released for reperfusion. Another group of mice (n = 8) underwent a sham operation and served as additional control animals. Six hours after ischemia/reperfusion, the mice were killed in order to assess the intestinal injury (intestinal protein content, mucosal disaccharidase activity, and intestinal histologic findings) and the systemic consequences (bacterial translocation, serum interleukin-6, and lung myeloperoxidase activity). A second set of mice (n = 55) underwent identical gavages and ischemia/reperfusion and they were followed for survival. Compared to AA, enteral glycine administered prior to intestinal ischemia/reperfusion injury significantly preserved mucosal indices and intestinal histology and decreased lung myeloperoxidase activity. Survival was also significantly increased in animals receiving glycine compared to AA control mice. These data suggest that enteral glycine supplementation may be beneficial in attenuating intestinal ischemia/reperfusion injury and its related systemic effects in this murine model.

Animals↗

PubMedDate not supplied

Chronic pathophysiologic elevation of corticosterone after thermal injury or thermal injury and burn wound infection adversely affects body mass, lymphocyte numbers, and outcome.

The purpose of the present studies was to investigate the effect of glucocorticoids on catabolism and lymphocyte numbers in a rat model of thermal injury or thermal injury plus burn wound infection. Thermal injury alone caused only an acute increase in plasma corticosterone concentrations. Furthermore, body weight declined moderately (5%), and lymphocyte numbers in lymph nodes draining the burn wound and blood increased markedly, whereas splenic lymphocyte numbers declined by about 60%. By contrast uninjured rats subjected to chronic elevation of corticosterone by corticosterone pellet implantation showed large decreases in body weight and lymphocyte numbers in all tissues examined. The combination of injury and chronic corticosterone elevation resulted in body weight and lymphocyte changes intermediate between injury alone and corticosterone treatment alone. Chronic elevation of corticosterone for 4 days before burn wound infection significantly decreased survival time and survival. Burn wound infection immediately after injury caused chronic elevation of endogenous plasma corticosterone and body weight and numeric lymphocyte changes that were remarkably similar to those of uninjured rats treated with corticosterone. Finally, the glucocorticoid receptor antagonist RU 486 significantly increased survival time in thermally injured, burn wound-infected rats. These results lend support to a hypothesis that chronic elevation of plasma cortisol concentrations as observed in patients with burns may be deleterious.

Analysis of Variance↗

PubMedDate not supplied

Changes in memory and naive CD4+ lymphocytes in lymph nodes and spleen after thermal injury.

T cells expressing CD4 can be further subdivided by their expression of CD45R. In humans, CD45RO+ cells function as memory T cells, and CD4+CD45RA+ function as naive T cells, i.e., cells that have never previously encountered antigen. In the rat, similar functional division of CD4 cells can be made with antibody OX-22 (anti-CD45RC) with CD4+CD45RC- and CD4+CD45RC+ identifying the memory and naive phenotypes respectively. With use of the rat model, we studied the effect of burn injury on CD4 cell subpopulations and memory and naive T cells in lymph nodes draining the burn wound (NDB) and spleen. In the NDB we found that numbers of memory and naive CD4 cells increased significantly as a function of time after burn injury, and that this increase was greater for naive cells (5.7-fold) than for memory cells (4.1-fold). However, in the spleen, we found memory T-cell numbers decreased significantly on postburn days 12 and 18, whereas naive CD4 cells in the spleen manifested no changes at any time after burn. These results may be explained by the different trafficking patterns of memory and naive cells. Based on the cell surface marker, L-selectin, naive cells preferentially migrate into the NDB where they undergo differentiation into memory cells. Memory cells selectively migrate into inflamed burned tissue, which may account for their lesser-fold increase in NDB when compared to naive cells, and their decreased numbers in the spleen after burn injury.

Analysis of Variance↗