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Biomedical subjects

S Levine

Publications and source records attributed to S Levine.

At least 361 records · Page 20Linked to original sources
PubMed1984

Predictability and coping with separation in infant squirrel monkeys.

Twelve infant squirrel monkeys were separated from their mothers once every 48 hr for a total of 20 separations. Half of the infants experienced separations for a fixed interval (FI) of 30 min. The remaining 6 infants experienced separations for a variable interval (VI) which averaged 30 min. During the separation periods, movement and vocalizations were recorded. Blood was sampled for later cortisol assay after the 1st, 5th, 10th, 15th, and final separation. The FI group showed increased levels of movement and vocalization over repeated separations when compared with the VI group. Cortisol showed significant increases over basal levels and remained elevated throughout the entire period in both groups. These findings suggest that predictability may be more stressful than unpredictability when organisms cannot control the predicted event.

Adaptation, Psychological↗
PubMed1984

Behavioral control, aversive stimulus frequency, and pituitary-adrenal response.

Six females rats were trained to lever press under a free operant shock-postponement schedule. Each subject had a yoked control which received shock whenever the subject did. The shock-postponement interval (R-S) was varied from 5, 10, 20, 40, to 80 s over blocks of sessions. Corticosteroid levels were taken prior to training and before and after selected sessions. The rate of responding and the rate of shock were inversely related to the R-S interval. Corticosteroid levels were unrelated to the R-S parameter, although steroid samples taken during experimental periods were significantly elevated above preexperimental basal levels. Corticosteroid levels of avoidance subjects were significantly higher than basal levels at the beginning of a session. By the end of a session, these levels were significantly reduced, although still above basal levels. The results were reversed for the yoked control subjects. Their presession corticosteroid levels, although elevated over basal levels, were lower than postsession levels. The implication of these results for the notion that anticipation and control affect levels of arousal is discussed.

Animals↗
PubMed1984

Zetidoline, a new antipsychotic. First controlled trial in acute schizophrenia.

Zetidoline (ZTD), a compound chemically unrelated to any available antipsychotic, with selective dopamine receptor-blocking properties, was compared with haloperidol (HLP) in a double-blind study on 56 in-patients who had either first episodes or acute relapses of schizophrenia. ZTD was found to be safe, as effective as HLP, and to produce significantly fewer extrapyramidal side-effects (EPS).

Acute Disease↗
PubMed1984

Influence of social variables on the biobehavioral response to separation in rhesus monkey infants.

Effects of social stimuli on behavioral and physiological responses to separation were examined in 4-month-old rhesus monkeys. Infants were removed from their social group under 3 counterbalanced conditions: (1) infant totally isolated from its familiar physical and social environment and placed alone in a cage for 4 days; (2) "mother in"--housing the infant in a single cage in front of its social group with mother remaining in the group; (3) "mother out"--similar situation, except that mother was removed from the group during separation. Infant behavior was recorded, and, at selected times during separation, a blood sample was obtained for analysis of plasma cortisol. Infants rarely vocalized when totally isolated, but showed high vocalization and movement in the presence of their social groups. Vocalization was transiently higher in mother-out condition than in mother-in condition. Infants never showed signs of depression. Plasma cortisol response did not differentiate between groups. Animals showed significantly high levels of plasma cortisol 3 hours following separation. These data indicate that the responses of the infant following separation are attempts to produce effective coping responses. The concepts of "protest" and "despair" are discussed as they relate to behavioral differences observed following different separation paradigms.

Animals↗
PubMed1983

Tin salts prevent the plasma cell response to metallic tin in Lewis rats.

Inoculation of metallic tin powder produced marked proliferation of plasma cells and Russell body cells in draining lymph nodes. Prior, but not concurrent, administration of a soluble tin salt in the drinking water prevented the plasma cell hyperplasia. Various Na, Zn, Ag, and Cu salts were not inhibitory. The inhibitory effect of tin salts was detected as long as 2 months after the pretreatment was stopped. If the plasma cell response to metallic tin were due to an immunologic reaction, then the inhibition by a soluble tin salt may be a form of immunologic tolerance.

Animals↗
PubMed1983

Plasmacellular and granulomatous splenomegaly produced in rats by tin.

Two intravenous inoculations of metallic tin powder caused a striking, self-limited enlargement of the spleen up to five or six times its normal size. In addition to epithelioid cell granulomas in response to the foreign particles, the spleen contained extensive accumulations of plasmablasts, plasma cells, and plasma cells containing Russell bodies. The proliferative activity of the immature plasma cells was indicated by the high incidence of mitoses and cells labeled with tritiated thymidine. In contrast, the granulomas had no mitoses or labeling. A single intravenous injection of tin usually produced little or no reaction in the spleen despite an abundance of tin particles. Two intravenous injections or one intravenous and one intraperitoneal inoculation were much more effective. Experiments on route, interval, and dose suggested that the first dose of tin prepared the spleen in some manner while the second dose actually elicited the reaction. Pertussis vaccine or glucan could substitute for one of the tin injections. This new model is of interest for the study of plasma cell hyperplasia and also for revealing the pathogenic potential of metallic tin.

Animals↗
PubMed1983

Localization of goldthioglucose and bipiperidyl mustard lesions near artificial disruptions of the blood-brain barrier.

Administration of goldthioglucose (GTG) or bipiperidyl mustard (BPM) causes obesity and lesions in hypothalamus, medulla, and other regions of the brain. Each of these lesions is adjacent to one of the specialized circumventricular areas that differ from the remainder of the brain in their natural lack of a blood-brain barrier. In the present work, the blood-brain barrier was artificially disrupted by a large thermal injury of the cerebral cortex. In rats and mice prepared in this manner, both chemicals induced lesions in the viable brain tissue adjacent to the thermal injury. This provides strong support for the role of the blood-brain barrier in the localization of GTG and BPM lesions in hypothalamus and medulla. Localization of lesions near thermal injuries was much less with GTG than with BPM. This suggests that factors other than blood-brain barrier are also involved in the localization of GTG lesions. These findings not only help to elucidate the pathogenesis of the hypothalamic lesions, but they also open a new approach to work on the role of receptors, vasoactive substances, and other intermediaries in the mechanism of GTG damage.

Animals↗
PubMed1983

Influence of perinatal malnutrition on adult physiological and behavioral reactivity in rats.

A series of experiments examined the behavioral and pituitary-adrenal response to novelty of perinatally malnourished rats tested as adults after nutritional rehabilitation begun at weaning. Neither the behavioral measures of ambulation, rearing and defecation, nor the plasma corticosterone response to a brief exposure to an open field differentiated the previously malnourished subjects from controls. Similar to controls, previously malnourished subjects were also capable of displaying a graded corticoid elevation to environments increasingly different from the home cage. However, exploratory behavior, as measured by head-dip frequency and duration in the hole-board, was reduced in the previously malnourished rats. Although latency and amount of fluid consumed in a novel environment did not differ, previously malnourished rats were unable to use the cues associated with a consummatory behavior to modulate the pituitary-adrenal response to novelty. Thus, perinatal malnutrition does not influence either the behavioral or physiological activational response to novel stimulation but appears to alter the ability of the animal to use a consummatory behavior to modulate this response.

Animals↗
PubMed1983

Influence of perinatal malnutrition and early handling on the pituitary-adrenal response to noxious stimuli in adult rats.

A series of experiments examined the influence of perinatal malnutrition and infantile stimulation (preweaning handling) on the pituitary-adrenal response to novelty, electric shock and ether in adult rats. Neither early experience variable altered the magnitude or time course of the plasma corticosterone response to the combined stress of ether exposure and cardiac puncture. Although perinatal malnutrition did not change the magnitude of the adrenocortical response 15 min following a 1-min exposure to a novel test chamber alone or with 0.25 or 1.0 mA of scrambled electric shock, early handled subjects of both nutrition groups displayed lower corticoid elevations compared to nonhandled rats. Additionally, all subjects showed a lower corticoid elevation to the novel chamber without shock compared to the chamber plus electric shock, with females being able to display a differential corticoid response to the two shock levels. Perinatal malnutrition did not alter the magnitude and time course of the ACTH response to a 1-min exposure to a novel chamber alone or with ether. Thus, perinatal malnutrition does not appear to alter either the basal levels of ACTH and corticosterone or the response of these hormones following the stressors examined. Early handling modulated the response to novelty and electric shock but not ether, suggesting that the latter response is mediated by brain regions not influenced by infantile stimulation. Finally, the results of these studies indicate that the magnitude of the pituitary-adrenal response reflects different intensity levels of electric shock in female rats.

Adrenocorticotropic Hormone↗
PubMed1983

The decreased growth rate of obese strain chicken thyroid cells provides in vitro evidence for a primary target organ abnormality in chickens susceptible to autoimmune thyroiditis.

The obese (OS) strain of chickens develops severe autoimmune thyroiditis, whereas its progenitor, the Cornell (CS) strain, rarely does. To detect possible developmental abnormalities in the OS thyroid, CS and OS embryonic thyroid epithelia were cultured in vitro and compared in several assays for growth and DNA metabolism. It was found that OS thyroid cells incorporated less tritiated thymidine, reached lower saturation densities, and possessed a significantly longer doubling time (26.1 hr) than CS cells (17.6 hr). The decreased growth rate of OS thyroid cells correlated with their inability to condition their own media. These abnormalities in the embryonic development of OS thyroid cells were discussed in the context of factors predisposing to autoimmune thyroiditis.

Animals↗
PubMed1983

Suppression of experimental allergic encephalomyelitis by tilorone: cell transfer and interferon studies.

Tilorone is known to induce interferon and to suppress experimental allergic encephalomyelitis (EAE) produced by active immunization. In the present work, tilorone was given to donors or recipients of the passive transfer form of EAE, using a localized variety of 1 or 4 days duration and a nonlocalized form of 8 days duration. The results indicated that tilorone inhibited EAE by retarding the clonal expansion in response to antigen, by a reversible inhibition of EAE effector cells, and probably by an effect on nonspecific reactive cells in the perivascular inflammatory infiltrates. Inhibition of EAE was not mediated by the induction of interferon, but was associated with depletion of T lymphocytes.

Animals↗
PubMed1983

The pituitary-adrenal response to novel stimulation and ether stress in young adult and aged rats.

Pituitary-adrenal responsiveness to stress induced by either psychological (novelty) or physiological (ether) stimuli was examined in young (3 to 6 months) and old (24 to 27 months) male and female rats. In Experiment 1, subjects were placed in a novel environment for 3 min. Blood samples were collected at 0, 15, 30, 45, and 60 min. In Experiment 2, a blood sample was collected from experimental subjects immediately following 15 min in a novel environment; a basal sample was collected from control subjects. In Experiment 3, basal and stress blood samples were collected from subjects exposed to ether vapors. Blood samples were assayed for plasma corticosterone content. The major findings were: (1) no change with age in either sex in basal corticosterone levels or in the time course of the adrenocortical response; (2) no change with age in males in stress-induced increments in corticoids; (3) no change with age in females in corticoid elevations induced by a mild stressor (Experiment 1), but a decrement in elevations induced by more potent stressors (Experiments 2 and 3).

Aging↗
PubMed1983

Behavioral, but not physiological, adaptation to repeated separation in mother and infant primates.

Mother and infant squirrel monkeys were subjected to a series of brief separations in order to evaluate how behavioral and physiological responses change following multiple exposures to stress. Beginning when the infants reached three months of age, their behavioral and hormonal responses were assessed during six 1-hr separations; and additional five dyads served as controls for the effect of repeated disturbance. The separated infants showed a marked and progressive decrease in distress calling across time, but no change was observed in the high levels of agitated activity or the plasma cortisol response to separation. This finding questions the traditional use of distress vocalizations as a measure of stress and indicates that certain types of behavior can change independently of physiological arousal responses, which may continue to occur even after repeated exposures to stress.

Adaptation, Psychological↗
PubMed1983

Histochemical observations on rodent brain melanin.

The presence or absence of melanin and neuromelanin in rodent brain was determined by means of light microscopic histochemistry. Melanin in melanocytes located in meninges and along cerebral capillaries occurred in abundance in C57 black mice and to a lesser extent in pigmented rats. Meningeal melanin bound cupric and ferrous ions, reduced ferricyanide, and appeared golden-brown in the bright field, light scattering in the dark field, and absorbant in the ultraviolet. Eleven aging albino rats were utilized to ascertain if the age related pigment, neuromelanin was present in neurons of the substantia nigra. Evidence of neuromelanin was not obtained as the cupric and ferrous ion uptake reactions were negative and neuromelanin could not be seen in the bright or dark field. Substantia nigra neurons did exhibit histochemical reactions for lipofuscin, however, as acid phosphatase positive, periodic acid-Schiff positive, and autofluorescent granules were demonstrated.

Aging↗