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Biomedical subjects

S Levine

Publications and source records attributed to S Levine.

At least 289 records · Page 16Linked to original sources
PubMed1987

A method for evaluating regional effects of cytotoxic drugs on proliferating cells in lymph nodes.

Tin powder, injected into both hindfeet of rats, caused intense proliferation of the plasma cell series in the draining lymph nodes. The hyperplasia was evaluated by weight and by histology of the nodes. This simple, rapidly executed model was used to evaluate the delivery of locally injected cytotoxic drugs to regional lymph nodes. Inhibition of hyperplasia was compared to both internal controls (contralateral node) and external controls. Mitoxantrone and methotrexate, injected locally according to certain doses and schedules, were effective in reducing the lymph node hyperplasia with little or no systemic effects. This model should assist in the evaluation of drugs, schedules, and adjuvants that might be used in the regional treatment of lymph node hyperplasia or metastic neoplasia.

Animals↗
PubMed1987

Nonspecific stress prevents relapses of experimental allergic encephalomyelitis in rats.

Rats with experimental allergic encephalomyelitis (EAE) develop paralysis, from which most of them recover. It has been hypothesized that spontaneous remission in EAE is due to the stress of paralysis and the subsequent hypersecretion of endogenous immunosuppressive adrenal glucocorticoids. Spontaneous relapse after a remission is thought to occur when the stress of paralysis and the adrenal response to it are terminated. In the present work, this theory has been tested in a newly developed relapsing form of EAE in rats. After an initial attack characterized by paralysis, the control rats had a remission and then a second episode of paralysis (relapse). In contrast, rats subjected to restraint during the remission period were protected from relapses. Injections of adrenal glucocorticoids during the remission had a similar protective effect. These findings support the hypothesis that remissions and relapses in EAE are caused by the occurrence and subsequent disappearance of the adrenals' immunosuppressive response to the stress of paralysis, because the addition of stress during the period of remission maintained the adrenals' hyperactive state and thereby prevented relapses.

Adrenal Glands↗
PubMed1987

Behavioral stress impairs long-term potentiation in rodent hippocampus.

A number of hormones secreted from the pituitary-adrenal system during stress affect learning and memory processes. The phenomenon of hippocampal long-term potentiation (LTP) is viewed by many as a putative mechanism of memory storage and has proved a most valuable model for study of neuronal plasticity at the cellular level. The present study was conducted to investigate the possibility that stressful events which occur prior (in vivo) to the preparation of brain slices may influence the electrophysiology of the in vitro hippocampal explant when tested for LTP. Adult male rats (Long-Evans male X Sprague-Dawley female) were pair-housed 1 week prior to testing. One animal in each pair was either placed in a restraining tube for 30 min and received no tail shocks (Restraint) or placed in a restraining tube and received tail shocks (1 microA, 1 s) every minute for 30 min (Restraint + Shock). The other animal in each pair was taken directly from the home cage and received no restraint or tail shock (Control). In vitro hippocampal slices were then prepared immediately from these animals according to standard methods. Our results demonstrate a marked impairment of LTP in hippocampal explants taken from rats exposed to stress. The significance of this result with respect to cellular mechanisms underlying the relationship between stress, cognition, and learning is discussed.

Animals↗
PubMed1987

Prediction of lactate threshold and fixed blood lactate concentrations from 3200-m running performance in male runners.

To determine the effectiveness of a 3200-m time trial for predicting VO2 and running velocity at lactate threshold (LT), fixed blood lactate concentrations of 2.0, 2.5, and 4.0 mM, and peak, 42 male runners (means age = 31.1 +/- 8.3 years; means ht = 176.8 +/- 6.6 cm; means wt = 70.4 +/- 10.0 kg) completed a VO2 peak/LT test and a 3200-m time trial. The continuous treadmill protocol started at 0% grade 150 m/min and increased 10 m/min every 3 min until exhaustion. Velocity at LT, 2.0, 2.5, and 4.0 mM was determined from individual velocity blood lactate relationships, and VO2 values were determined from individual plots ov VO2 vs velocity. VO2 peak and velocity peak were chosen as the highest values observed. Oxygen uptake at LT, 2.0, 2.5, 4.0 mM, and peak was 52.51, 56.61, 58.31, 61.70, and 64.21 ml/kg.min-1, respectively, while the velocities associated with LT, 2.0, 2.5, 4.0 mM, and peak were 235.5, 251.5, 259.8, 273.5, and 285.5 m/min, respectively. During the 3200-m time trial (means time = 11.28 +/- 0.96 min), 400-m split times and cumulative times were recorded. Twenty-nine subjects were randomly assigned to a validation sample and the remaining subjects were used for cross-validation purposes. Regression analysis revealed that a 3200-m time trial was a good predictor of both VO2 (ml/kg.min-1) and velocity (m/min) at LT, 2.0, 2.5, 4.0 mM, and peak.

Adult↗
PubMed1987

Tonic adaptation in symptomatic and asymptomatic subjects.

Tonic accommodation and tonic vergence were measured in symptomatic and asymptomatic subjects before, during, and after 45 min of binocular reading at near (5 D). Reading produced significant increases in both tonic levels, with the magnitude of change being similar in the two groups. After reading, both groups exhibited rapid loss of the tonic vergence effect, but showed no evidence for decay of the tonic accommodation effect. Differences between the groups were observed in the rate of adaptation during the course of reading, with both tonic components increasing more slowly for the symptomatic subjects than for the asymptomatic subjects. In addition, baseline tonic accommodation was significantly higher in the symptomatic group than in the asymptomatic group. The results suggest that although the failure to undergo tonic oculomotor adaptation is not a causal factor in asthenopia, the initial steady-state level and/or subsequent temporal changes of tonic accommodation and tonic vergence may be related to nearwork symptomatology.

Accommodation, Ocular↗
PubMed1987

Tonic accommodation, accommodative hysteresis, and refractive error.

Accommodative hysteresis was compared in high myopes, low myopes, emmetropes, and hyperopes. Subjects consisted of 48 visually normal young adults who were fully corrected for their ametropia and equally distributed among the four refractive categories. Baseline measures of tonic accommodation, nearpoint, and farpoint were followed by a 10 min period of monocular fixation on a target which provided a stimulus equal to the subject's accommodative amplitude. The tonic measures were repeated immediately after fixation and were followed by either reassessment of the nearpoint and farpoint, or a 20 min period in darkness with reassessment of the tonic level at 5-min intervals. The period of sustained maximal focus produced significant increases in both tonic accommodation and the accommodative nearpoint in each refractive group. Although the magnitude of change was statistically equivalent across groups, a tendency to greater increases in tonic accommodation was noted for the high myopes. Although the farpoint remained relatively stable in the individual refractive groups, a slight inward shift was found in the combined sample. The tonic change diminished primarily during the first 5 min in darkness, with no significant difference in either the rate or degree of decay in the various refractive groups. The results indicate no clear association between susceptibility to accommodative hysteresis and refractive category.

Accommodation, Ocular↗
PubMed1987

Demonstration that glycoprotein G is the attachment protein of respiratory syncytial virus.

Two monospecific rabbit antisera to the G glycoprotein, one induced with purified G and the second with a recombinant vaccinia virus containing the gene for G, inhibit the attachment of purified [35S]methionine-labelled Long strain of respiratory syncytial virus to monolayers of HeLa cells. Attachment was not inhibited by monospecific rabbit antisera to glycoprotein F induced with either purified F or with a recombinant vaccinia virus containing the gene for F.

Antibodies, Monoclonal↗
PubMed1987

Diaphragmatic pressure waveform can predict electromyographic signs of diaphragmatic fatigue.

To evaluate the relationship between diaphragmatic pressure (Pdi) waveform and electromyographic (EMG) signs of diaphragmatic fatigue (DF), 11 chronic obstructive pulmonary disease (COPD) subjects underwent a 12-stage graded treadmill exercise test (GXT). No COPD subjects completed the GXT; all stopped exercising due to dyspnea. We then used the crural diaphragmatic EMG (EMGdi) to divide the COPD subjects into a group that exhibited EMGdi signs of fatigue during the GXT (i.e., F group) and one that did not (i.e., NF group); three COPD subjects were classified as F, and eight COPD subjects were classified as NF. At end exercise, F and NF groups did not differ with respect to peak inspiratory Pdi swing (peak Pdi); however, they did differ with respect to percent of peak Pdi manifest at 50 and 90% of inspiratory time (TI). At 50% TI, NF = 88 +/- 3%, F = 60 +/- 1%, P less than 0.01; likewise at 90% TI, NF = 58 +/- 5%, F = 12 +/- 10%, P less than 0.01. Since peak Pdi occurred in both groups during the initial 50% of TI, these data indicate that the F group maintained Pdi less well than the NF group during the latter half of TI. Based on the above results and other data in the manuscript, we suggest that this change in Pdi waveform can predict EMG signs of DF.

Diaphragm↗
PubMed1987

Choroid plexitis in white-tailed deer (Odocoileus virginianus) in southern New York State.

Brains, spinal cords, nerve roots, nerves and muscle tissues were removed from deer in southern New York State and examined for histologic evidence of infection by the causative agent of Lyme disease, Borrelia burgdorferi. There was no histologic evidence of this infection and only four of 26 deer had serologic evidence of past infection despite the fact that all were parasitized by the tick vector, Ixodes dammini. Of these ticks, 21% were carrying B. burgdorferi. In contrast, most of the deer had choroid plexitis. All but one of 48 deer tested were infected with Trypanosoma cervi, 20 of 24 deer had sarcocystis in skeletal muscles and two had dural lesions probably due to the nematode Pneumostrongylus tenuis. The causal relationship between choroid plexitis and trypanosomiasis is discussed.

Animals↗
PubMed1987

A comparative trial of a new antidepressant, fluoxetine.

This clinical trial of a new antidepressant, fluoxetine, shows it to be as effective as a standard tricyclic drug, imipramine. It is effective as a single daily dose and is free of any significant side-effects. It is less sedative and appears to cause fewer problems of weight increase. The three scales used to assess efficacy showed a very positive correlation.

Adult↗
PubMed1987

The effects of metallic tin on background plaque-forming cells, immunoglobulins and the immune response.

Inoculation of metallic tin powder into Lewis rats resulted in marked enlargement of the draining lymph nodes. Plasma cells were the major contributors to the increase in cell mass. Certain immunologic aspects of this plasma cell lymphadenopathy were investigated. Immunoglobulin isotypes were distinguished and quantitated by fluorescence immunocytochemistry and rocket electrophoresis of lymph node extracts. Background plaque-forming cells directed against sheep red blood cells were increased. Specific activity was highest 4 days after inoculation of tin. Lymph nodes and spleen continued to increase in cell number so that total background activity attained a maximum at 14 days after inoculation of tin. Tin was a good adjuvant for plaque-forming cells in lymph nodes and for serum agglutinins (primary and secondary responses) when the rats were immunized with sheep red blood cells, even when the antigen was injected at a remote site. The plasma cell response to tin may be due to local polyclonal activation.

Adjuvants, Immunologic↗
PubMed1987

Psychological factors capable of preventing the inhibition of antibody responses in separated infant monkeys.

The capacity of infant squirrel monkeys to mount an antibody response to viral challenge was evaluated after removal from their mothers in several social and physical environments. Control and separated infants were injected with a benign virus, the bacteriophage X174, and levels of neutralizing antibody were assessed for 3 weeks. Infants separated alone in an unfamiliar environment showed a significant reduction in antibody levels as compared to control infants. Allowing infants to remain in the home environment, either alone or with peers, prevented this inhibition of antibody responses from occurring. Similarly, providing familiar peers in the novel environment facilitated the normal expression of antibody responses. These results indicate that the trauma of maternal separation is significantly reduced when infants are familiar with the separation environment or familiar social companions are available. The reduced antibody response was associated with the highest level of adrenal activation induced by the unfamiliar separation condition, but antibody titers and plasma cortisol levels could not be specifically correlated in individual infants.

Animals↗
PubMed1987

Effects of antihypertensive medications on vitality and well-being.

The effects of captopril, methyldopa, and propranolol were assessed for sense of well-being and vitality among 626 men with mild to moderate hypertension in a multicenter, randomized, double-blind clinical trial. After a 24-week treatment period, patients taking captopril, compared with patients taking methyldopa and propranolol, scored significantly higher on measures of well-being and vitality. In addition, patients on captopril had more favorable results in being able to keep up with their work and in not feeling tired or sleepy at work. The effects of each of the drugs manifested themselves at different periods. For example, the negative effects of methyldopa on vitality were evident by week 8, whereas the negative effects did not become manifest for propranolol until week 24. On the other hand, a steady progressive improvement in vitality scores was evident at week 8 and at week 24 for patients on captopril. The findings of the study also suggest that the effects of the treatment drugs were most marked in patients who had had previous antihypertensive medications and who were on single-drug therapy during the course of the clinical trial. Further, the differences between patients taking captopril and those on methyldopa and propranolol appear to be obscured by the addition of a diuretic. The findings of the study may guide the physician in orienting his or her patient and in planning and implementing a therapeutic regimen.

Adaptation, Psychological↗
PubMed1987

Primate vocalization: a psychobiological approach.

Scientific inquiry, for the most part, can be described as parochial. Not only are there clear demarcations between broad disciplinary categories (i.e., anatomy, physiology, psychology), but subspecialties are common within disciplines. Modern technology has made possible a trend toward greater and greater specialization. In fact, there are now areas of scientific investigation that did not exist a few years ago. This increasing specialization and its concomitant reductionism is not without its pitfalls and problems. There is a tendency to move away from the basic evolutionary concept of living organisms as organized systems functioning and adapting within an ecosystem. The laboratory scientist often ignores the inherent organization of living systems in favor of an intense pursuit of his or her particular chosen bit of the biological puzzle. However, there are still disciplines that not only subscribe to the notion of living organisms as organized systems but have made a valiant attempt to bring this concept under laboratory scrutiny. Often, in order to identify these endeavors, a technique is used to combine two or three words into one. Thus, we have several flourishing disciplines described as psychoneuroimmunology, psychoneuroendocrinology, neurochemistry, physiosociology, and so on. For the investigator who attempts a more integrated approach to the broad biological and psychological universe, the demands are heavy. He or she is faced with the need to maintain credibility in several disciplines, each of which is advancing at an accelerated pace. However, we feel that the value of an integrated approach that crosses traditional disciplinary lines will be illustrated in a small way by this article and, we hope, by the series of articles presented in this symposium section of Child Development.

Animals↗