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Biomedical subjects

S Levine

Publications and source records attributed to S Levine.

At least 253 records · Page 14Linked to original sources
PubMed1989

Intracoronary stents.

The use of balloon-expandable intravascular stents in atherosclerotic heart disease is currently being investigated as a feasible alternative/adjunct to more traditional methods of therapy, that is, coronary artery bypass surgery and percutaneous coronary angioplasty. Preliminary results of recent patient studies in the United States and Europe have demonstrated the ability of these stents to effectively maintain vessel patency and to potentially reduce restenosis rates both in peripheral and coronary arteries. Used in conjunction with other techniques (PTCA, laser, atherectomy devices), stents will hopefully increase the safety and long-term effectiveness of treatment of coronary artery disease by nonsurgical methods.

Adult↗
PubMed1989

Cochlear implant hearing performance at the University of Minnesota.

The hearing performance of six post-lingually deaf adults implanted with the Nucleus 22-channel device are presented. All patients achieved measurable open set speech recognition with implant alone. The best hearing performance was achieved with a combination of lipreading and cochlear implant. For this condition our group achieved an average open set speech discrimination score of 85% (CID sentences) and an average speech tracking rate of 70 words per minute. We attribute the success of our group to careful pre-operative selection, including attention to candidate motivation toward hearing rehabilitation.

Adult↗
PubMed1988

Ontogeny of type I and type II corticosteroid receptors in the rat hippocampus.

The ontogeny of the corticoid receptors in the rat hippocampus was examined by in vitro [3H]corticosterone (CORT) binding to soluble molecules in the cytosol, using the selective Type II glucocorticoid agonist, RU 28362, to discriminate between Type I and Type II receptor sites. Type I receptors were undetectable until 8 days after birth. From this age on, the receptor showed adult characteristics for both the binding capacity (Bmax) and affinity (Kd). The Type II receptor concentration increased gradually over the observed period; however, at 3 weeks of age concentrations were still only about 65% those found in adults. The binding affinity of Type II to CORT was high during the first week of life but decreased thereafter towards adult value. These data thus suggest clear distinctions in the developmental patterns of Type I and Type II receptors for corticosteroids in the rat.

Aging↗
PubMed1988

Ontogeny of the type 2 glucocorticoid receptor in discrete rat brain regions: an immunocytochemical study.

The ontogeny of the Type 2 glucocorticoid receptor (GR) in the rat brain was examined using a monoclonal antibody raised against the rat liver GR. Marked changes both in the intensity and in the localization of GR immunoreactivity (GR-ir) were found to occur as a function of age and brain area examined. First, GR-ir was high perinatally and decreased to a low intensity of immunostaining around postnatal day 12 (pnd 12). Thereafter, GR-ir increased to a moderate intensity, which resembled adult levels by pnd 20 in most brain areas. Second, in some regions, such as the hippocampal CA3-4 pyramidal cell fields and the suprachiasmatic nucleus of the hypothalamus, GR-ir was only clearly present during the first postnatal week. Third, in the hippocampus, GR-ir localization showed a distinctive developmental trend towards greater compactness within the CA1-2 pyramidal cell fields and a greater restriction of immunoreactive staining to these cell fields with exclusion of the adjoining areas. Fourth, adrenalectomy reduced overall GR-immunopositive staining, which could be reversed by administration of the selective glucocorticoid agonist, RU 28362. Our results suggest that during ontogeny the glucocorticoid receptor system displays considerable plasticity. Such plasticity may provide a basis for understanding the role of glucocorticoids during brain development.

Adrenalectomy↗
PubMed1988

Effects of age, sex, and psychological disturbance on immunoglobulin levels in the squirrel monkey.

The following research assessed the influence of developmental, hormonal, and psychological factors on immunoglobulin and complement protein levels in the squirrel monkey. A cross-sectional life span study established that the developmental pattern of immunoglobulins and complement proteins was similar to that observed in humans. IgG and IgM levels rose progressively with age, while the complement system was mature at birth. In contrast to humans, this species showed a significant sex difference in IgG levels, with higher levels in males during both infancy and adulthood. Males also showed a greater antibody response to viral challenge than did females, and evaluation of gonadectomized subjects suggested that the sex difference in antibody production was testosterone-dependent. The effect of acute and sustained psychological disturbance on IgG levels was also evaluated in infant monkeys. Repeated, brief separations from the mother did not alter IgG levels, but IgG levels were suppressed after a 7-day removal from the mother. Therefore, despite the general view that immunoglobulin levels are relatively stable, these studies have established that immunoglobulin levels can be strongly influenced by hormonal and experiential factors in the squirrel monkey.

Aging↗
PubMed1988

Growth hormone releasing factor and somatostatin concentrations in the milk of lactating women.

The concentrations of growth hormone releasing factor (GRF) and somatostatin, two hypothalamic neuropeptides involved in the regulation of growth hormone secretion, were measured in human milk samples. The study was performed in healthy women within 48 h of delivery or during established lactation (between 1 and 64 weeks post delivery). No statistically significant correlation was found between the levels in milk of either of the neuropeptides and the gestational age at birth. However, lower values of GRF (23 +/- 4.7 pg/ml vs. 40.5 +/- 4.9 pg/ml) were found in milk obtained during established lactation than in milk obtained close to delivery. A positive correlation was observed between somatostatin and GRF concentrations in milk. The possible involvement of milk neuropeptides in the control of growth hormone secretion in the neonate, as well as in the regulation of other physiological processes, are evaluated.

Adolescent↗
PubMed1988

The role of antigen absorption in the resistance of brown-Norway rats to experimental allergic encephalomyelitis.

The designation of Brown-Norway (BN) rats as resistant to experimental allergic encephalomyelitis (EAE) is an oversimplification. Lewis rats are susceptible and BN rats are usually resistant to EAE after inoculation with guinea pig spinal cord or basic protein in Freund's adjuvant. However, EAE can be produced in BN rats by immunizing with rat cord and carbonyl iron, a particulate adjuvant. In the present work, the possibility that susceptibility of BN rats under these conditions is due only to the special qualities of the adjuvant has been eliminated by producing EAE in them without any adjuvant at all, merely by increasing the absorption and processing of the rat cord antigen. The susceptibility of the F1 hybrids is intermediate with respect to guinea pig cord antigen but it was equal to or greater than either parental strain when tested with rat cord antigen. Histologic evidence that BN rats do not absorb or process neural antigen as well as other strains, and the augmentation of EAE by increasing the dose and absorption of the inoculum, suggest that antigen absorption, processing and presentation is a "bottleneck" for development of EAE in BN rats. Absorption and processing of antigen should be considered along with cellular response, inflammatory mediators and epitope dominance when analyzing susceptibility and resistance to EAE.

Adjuvants, Immunologic↗
PubMed1988

Psychoendocrine aspects of mother-infant relationships in nonhuman primates.

Studies will be presented which examine the physiological and behavioral responses of squirrel monkeys and rhesus macaques following disruptions of mother-infant relationships. Reliable increases in circulating levels of plasma cortisol occur following separation of the infant from its mother. The presence of familiar conspecifics during the time of separation reduces the pituitary-adrenal response, compared to that elicited by total isolation. Visual access to the mother during separation also ameliorates the plasma cortisol response. However, when infants are separated in the presence of unfamiliar conspecifics, the physiological response is exaggerated compared to animals which are totally isolated. The behavior expressed by the infant during separation, particularly separation-induced vocalizations, is not concordant with this physiological index of affect. The rate of vocalization produced when the infant has visual access to the mother was higher than when the infant was totally isolated. However, when allowed access to familiar conspecifics, the rate of vocalization was lower than during total isolation, with no vocalization produced while the separated infant was in the unfamiliar social group. The curvilinear relationship between vocalization and the physiological index of arousal has led to a revision of the traditional concept that separation-induced infant vocalization is reflective of distress. These data support the hypothesis that vocalizations may serve as a coping response that reduces the physiological indices of arousal. Social interaction with familiar cospecifics may serve as a non-vocal coping response (e.g., proximity contact to other monkeys) which also reduces the behavioral and physiological responses to maternal separation.

Animals↗
PubMed1988

Family environment of adolescents and coping in the hospital.

The purpose of this study was to test the relationship between social environment and the activity of the HPA axis in adolescents. Ten elective admissions to Children's Hospital at Stanford were assessed by standard psychiatric interview. Five fulfilled criteria for a DSM-III diagnosis, five others did not. The groups were comparable in age, height, weight, SES, and number of previous hospitalizations. All subjects and their families completed the Family Environment Scale. All subjects had plasma cortisol concentrations determined on days 1, 3, and 5 of hospitalization and at the time of discharge. Samples were drawn under standardized conditions, after a brief interview during which potentially stressful events of the day were discussed. Results revealed that the five individuals with poor coping skills, as defined by the presence of a DSM-III diagnosis, had significantly higher peak concentrations of plasma cortisol, than the five psychiatrically normal subjects. Peak cortisol elevations occurred upon discharge from the hospital. Family environment in the two groups differed significantly on the dimensions of cohesion, conflict, control, and incongruence of perception of the environment among family members themselves. The findings support the hypothesis that social environmental characteristics are associated with psychiatric and physiological measures of coping.

Adaptation, Psychological↗
PubMed1988

Prolonged effect of psychological disturbance on macrophage chemiluminescence in the squirrel monkey.

The following study assessed changes in macrophage responsiveness after a 24-h period of psychological disturbance in mother and infant squirrel monkeys. Utilizing a luminol-dependent assay, an 80-min chemiluminescent burst was measured in blood monocytes in response to zymosan stimulation. Cells obtained from stressed mothers and infants showed significant increases in chemiluminescence (CL) as compared to baseline levels. Moreover, the elevated pattern of response persisted for at least 2 weeks after the mothers and infants were reunited. The initial change in CL was associated with increased pituitary-adrenal activity and leukocyte redistribution, but these measures returned to normal levels following reunion. Thus, this study has demonstrated a prolonged change in an immune parameter following a transient alteration in the psycho-endocrine status of the host.

Animals↗
PubMed1988

Linear seborrheic keratoses associated with underlying malignancy.

A clinical syndrome, consisting of eruptive linear seborrheic keratoses associated with adenomatous colonic polyps (malignant but without invasion of the stalk) and/or frankly invasive colonic adenocarcinomas, is described in five patients. Partial to almost complete regression of the cutaneous lesions over the succeeding months to years was noted after removal of the internal malignant tumors in all five patients. Resolving lesions were characterized by an accentuation of chronic inflammatory infiltrate both within the epidermis and dermis, suggesting perhaps that the regression of the skin lesions may be related to enhanced immunologic response concomitant with the removal of the underlying malignancy.

Adenocarcinoma↗
PubMed1988

Maternal deprivation potentiates pituitary-adrenal stress responses in infant rats.

In three experiments we examined the effect of maternal deprivation on the pituitary-adrenal response of 12-, 16- and 20-day-old rat pups to novelty stress. Infant rats were either deprived individually in heated incubators or left in the home nest with their mother and then tested for their corticosteroid response to 30-min exposure to a novel test arena (novelty-stress). In Experiment 1 we showed that the magnitude of the stress response was a positively accelerated function of the deprivation interval. Stress responses were not increased after 1 hour of deprivation, were modestly increased after 8 hours of deprivation, and were dramatically increased after 24 hours of deprivation. In Experiment 2 we asked whether potentiation of the stress response resulted from the maternal or the nutritive components of the deprivation procedure. Pups were tested under one of four treatment conditions formed by a 2 (Maternally Deprived vs. Nondeprived) x 2 (Nutritively Deprived vs. Nondeprived) factorial design. At 12 and 16 days of age, potentiation of the stress response was traced to the absence of maternal care and not nutrients. At 20 days of age, both maternal and nutritive deprivation contributed to the potentiated stress response. The results of Experiment 3 showed that this effect was mediated, at least in part, by increased adrenocortical sensitivity to ACTH, because the corticosteroid response to exogenous ACTH administration was also increased by maternal deprivation. These findings add to a growing body of literature that supports the concept of maternal regulation of infant physiology. They also support previous reports from this laboratory indicating that suppression of the pituitary-adrenal system is modulated by maternal variables during the preweaning period in the rat.

Age Factors↗