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Biomedical subjects

S Epstein

Publications and source records attributed to S Epstein.

At least 19 recordsLinked to original sources
PubMed1992

Effects of tamoxifen on bone mineral density in postmenopausal women with breast cancer.

BACKGROUND AND METHODS: Tamoxifen, a synthetic antiestrogen, increases disease-free and overall survival when used as adjuvant therapy for primary breast cancer. Because it is given for long periods, it is important to know whether tamoxifen affects the skeleton, particularly since it is used extensively in postmenopausal women who are at risk for osteoporosis. Using photon absorptiometry, we studied the effects of tamoxifen on the bone mineral density of the lumbar spine and radius and on biochemical measures of bone metabolism in 140 postmenopausal women with axillary-node-negative breast cancer, in a two-year randomized, double-blind, placebo-controlled trial. RESULTS: In the women given tamoxifen, the mean bone mineral density of the lumbar spine increased by 0.61 percent per year, whereas in those given placebo it decreased by 1.00 percent per year (P less than 0.001). Radial bone mineral density decreased to the same extent in both groups. In a subgroup randomly selected from each group, serum osteocalcin and alkaline phosphatase concentrations decreased significantly in women given tamoxifen (P less than 0.001 for each variable), whereas serum parathyroid hormone and 1,25-dihydroxyvitamin D concentrations did not change significantly in either group. CONCLUSIONS: In postmenopausal women, treatment with tamoxifen is associated with preservation of the bone mineral density of the lumbar spine. Whether this favorable effect on bone mineral density is accompanied by a decrease in the risk of fractures remains to be determined.

Alkaline Phosphatase↗
PubMed1992

The effect of a new vitamin D analog, 22-oxa-1 alpha,25(OH)2D3, on bone mineral metabolism in normal male rats.

The in vivo effects of 22-oxa-1 alpha,25 dihydroxyvitamin D3 (OCT), on bone mineral metabolism were investigated in normal male Sprague-Dawley rats. The rats were administered either vehicle (control), low-dose OCT (25 ng/100 g body weight), or high-dose OCT (250 ng/100 g body wt). High-dose OCT increased serum ionized calcium (P less than 0.05) and decreased serum parathyroid hormone (PTH) (P less than 0.05) at all time points and increased serum bone Gla protein on days 7 and 28 (P less than 0.05) compared with controls. Low-dose OCT decreased serum PTH at all the time points (P less than 0.05) compared with controls. Tibial bone histomorphometry showed no significant differences between the two doses of OCT and controls. We found that OCT has minimal direct effects on bone metabolism in normal male rats in contrast to 1,25 dihydroxyvitamin D3. This property may be advantageous in the treatment with OCT of cell-proliferative diseases.

Analysis of Variance↗
PubMed1992

Effect of increased metabolic rate on oxygen isotopic fractionation.

16O16O is preferentially used over 18O16O (a stable isotope of oxygen comprising about 0.2% of atmospheric O2) as oxygen is consumed during respiration in humans (Epstein and Zeiri, 1988, Proc. Natl. Acad. Sci. USA 85: 1727-1731). To test the hypothesis that oxygen isotopic fractionation is related to the metabolic rate, 8 healthy adults performed 5 min of constant work rate cycle ergometer exercise below and above their anaerobic threshold. Moreover, 3 subjects performed an incremental exercise to the limit of tolerance. Oxygen uptake (VO2) was measured breath by breath. Samples of the exhaled breath for oxygen isotope measurement were obtained at rest and at various times during exercise and recovery. Oxygen isotopic fractionation was determined by isotope ratio mass spectrometry and calculated as the ratio of the degree of fractionation to the oxygen consumed in the breath sample (Z value). For the constant work rate protocol, both low and high intensity exercise resulted in a significant decrease in Z compared to the rest values (P less than 0.01). However, for the high intensity exercise the reduction in fractionation was greater compared to the low intensity protocol (P less than 0.05). For the incremental test, there was a significant negative correlation between oxygen isotopic fractionation and VO2 expressed as percent of the maximal oxygen uptake (r = -0.91, P less than 0.0001). These data suggest that during exercise low-fractionating processes become more important as limiting steps for O2 transport.

Adult↗
PubMed1992

Irrational reactions to negative outcomes: evidence for two conceptual systems.

According to cognitive-experiential self-theory (CEST), individuals have 2 systems for processing information, a rational system and an experiential system. Research conducted under norm theory (NT) has provided impressive evidence of an if only (IO) effect associated with postoutcome processing of aversive events that are highly consistent with formulations in CEST. Two studies involving vignettes adapted from NT were conducted that tested 4 hypotheses and corollaries derived from CEST. It was demonstrated, in support of hypotheses, that the IO effect can be obtained with ratings of one's own and of a protagonist's specific behaviors, as well as with ratings of a protagonist's diffuse emotions (the usual procedure); that a rational orientation decreases the IO effect; that increasing the intensity of outcomes increases it; and that priming the experiential system reduces people's ability to subsequently think rationally. The theoretical and research implications of these findings are discussed.

Adult↗
PubMed1992

Coping ability, stress, productive load, and symptoms.

A study of 450 college students demonstrated (a) the importance of a distinction between self-produced and externally produced stressors, (b) the usefulness of a construct of productive load, and (c) stronger relations of the Constructive Thinking Inventory than of the Hardiness Questionnaire with productive load and with mental and physical symptoms. Because a major path through which coping ability influences symptoms is negative emotions, the widely recommended practice of partialing self-reported negative affect out of relations among coping, stress, and symptoms is often inappropriate. However, as total daily stressors (e.g., hassles) consist largely of self-produced stressors, it is highly confounded with coping ability, and it is therefore important to partial coping ability out of relations between total stressors and other variables.

Adaptation, Psychological↗
PubMed1992

Coping ability, negative self-evaluation, and overgeneralization: experiment and theory.

Responses of 3 groups of Ss differing in general coping ability, as measured by the Constructive Thinking Inventory, were compared on matched sets of items that differed according to whether the outcomes were positive or negative and directed at the self or at others. All groups reported widespread overgeneralization to items with favorable outcomes. Groups differed strongly and consistently only in response to unfavorable outcomes directed at the self, with poor constructive thinkers reporting more negative overgeneralization than others following such outcomes. It was concluded that poor constructive thinkers have a selective bias toward making negative inferences about the self, which has widespread implications for their general coping ability. A theoretical framework is presented for understanding why individuals acquire and maintain negative self-schemata, which has implications for depression and self-esteem as well as for general coping ability.

Adaptation, Psychological↗
PubMed1992

Cognitive-experiential self-theory and subjective probability: further evidence for two conceptual systems.

Three experiments (N = 1,331) demonstrated that research findings on suspiciousness about coincidences (Miller, Turnbull, & McFarland, 1989) can be accounted for in terms of subjective probability, as predicted by cognitive-experiential self-theory (CEST) but in contrast with the norm theory (NT) account offered by Miller et al. (1989). Ss participated in a hypothetical (Experiments 1 and 2) or real (Experiment 3) lottery game in which they chose between 2 bowls offering equivalent probabilities of winning or losing but differing with respect to absolute numbers (e.g., 1 in 10 vs. 10 in 100). Responses across 4 conditions (2 probability levels x 2 outcome types) and across the 3 experiments supported predictions derived from CEST but not those derived from NT. Results are discussed in terms of 2 conceptual systems, rational and experiential, that operate by different rules of inference.

Adult↗
PubMed1992

Evidence that cyclosporine G is less deleterious to rat bone in vivo than cyclosporine A.

We have previously shown that CsA administration to rats causes a high turnover bone loss with bone resorption exceeding bone formation. Similar findings have been reported in renal and cardiac transplantation patients administered CsA. Cyclosporine-G (CsG), a natural equipotent immunosuppressive analogue of CsA, has been shown to be less nephrotoxic than CsA. We therefore compared the effects of CsG and CsA on bone mineral metabolism. Sixty male Sprague-Dawley rats were divided into 3 equal groups as follows: group A (n = 20) was the control; group B (n = 20) received CsA 15 mg/kg by daily gavage; and group C received CsG 15 mg/kg by daily gavage for 28 days. Rats were bled weekly for measurement of circulating biochemical parameters of bone mineral metabolism and after sacrifice on day 28, the tibiae were removed for histomorphometric analysis. The tibial bone histomorphometry revealed that the percentage of bone volume was significantly reduced, and the osteoclast count increased in both the CsA and CsG group, but significantly less so in the CsG than the CsA group. Parameters reflecting bone formation in the CsG group were similar to controls but significantly different from the CsA group. Bone Gla protein levels in the CsA group were significantly increased compared with the control and CsG groups from day 14. Serum 1,25 dihydroxyvitamin D was increased significantly in the CsA group on days 14 and 28 compared with both control and CsG groups, and was significantly elevated in the CsG group compared with controls on the same days. We conclude that CsG is significantly less deleterious to bone mineral metabolism than CsA in the rat in vivo.

Animals↗
PubMed1992

The role of general hospitals in the privatization of inpatient treatment for serious mental illness.

For almost three decades, many have regarded general hospital psychiatric units as the most appropriate setting for acute treatment of persons with serious mental illness who were once treated mostly in state hospitals. The extent to which this transfer has taken place and the differences between public and private general hospitals have been unclear. Using data from the 1988 National Mental Health Facilities Study and published data from the 1970s, the authors found that nearly half of all general hospitals providing psychiatric services treat persons with serious mental illness. Significant differences in case and payer mix were observed between public and private general hospitals, although these differences were smaller than in the 1970s. The findings suggest increased involvement by private general hospitals in treating patients reimbursed by public payers, but the findings also indicate that persons with serious mental illness and those using Medicaid are still more prevalent in public general hospitals than in private ones.

Community Mental Health Services↗
PubMed1992

17 beta-estradiol prevents osteopenia in the oophorectomized rat treated with cyclosporin-A.

Cyclosporin-A (CsA) administered to the oophorectomized rat exaggerates the high turnover osteopenia associated with oophorectomy alone. This study investigated whether 17 beta-estradiol replacement could influence the development of osteopenia in the oophorectomized rat treated with CsA. Ninety female Sprague-Dawley rats, approximately 300 g in weight, were divided into 6 groups of 15 each and treated according to the following protocol: group A were sham operated (control), group B underwent oophorectomy (Ox), group C underwent Ox and received CsA (15 mg/kg, by daily gavage) for 28 days (Ox and CsA), group D underwent Ox and received CsA and a 0.1 mg 17 beta-estradiol pellet (EP) implanted sc (Ox, CsA, and EP), group E underwent Ox and received EP (Ox and EP), and group F, which was intact and nonoperated, received CsA (CsA). Rats were weighed and bled on days -7, 0, 7, 14, 21, and 28 for measurement of blood ionized calcium, bone Gla protein (BGP), 17 beta-estradiol, and PTH. Bone histomorphometry was determined after double tetracycline labeling. On day 28, serum 17 beta-estradiol was undetectable in groups B (Ox) and C (Ox and CsA), and similar to group A (control) in groups D (Ox, CsA, and EP), E (Ox and EP), and F (CsA). Oophorectomy resulted in a significant gain in weight in groups B (Ox) and C (Ox and CsA), which was prevented by 17 beta-estradiol in groups D (Ox, CsA, and EP) and E (Ox and EP). On day 28, serum BGP levels were higher in groups B (Ox; 73.58 +/- 3.63 ng/ml), C (Ox and CsA; 85.05 +/- 9.88), and F (CsA; 81.35 +/- 3.4) compared to group A (control; 46.07 +/- 5.52; P less than 0.05), while 17 beta-estradiol in groups D (Ox, CsA, and EP; 38.65 +/- 2.85) and E (Ox and EP; 41.89 +/- 1.89) prevented this rise (P = 0.01). BGP levels in group C (Ox and CsA) were higher on days 14 and 21 compared to group B (Ox). Groups D (Ox, CsA, and EP) and E (Ox and EP) had elevated blood ionized calcium levels from day 7 onward. Serum PTH levels were unchanged. Histomorphometric analyses of tibial metaphyses revealed increased parameters of bone formation and resorption, with significant loss of bone volume, in groups B (Ox; 12.03 +/- 1.40%) and C (Ox and CsA; 11.43 +/- 2.20) vs. group A (control; 24.36 +/- 2.37; P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗