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Biomedical subjects

M Seeman

Publications and source records attributed to M Seeman.

At least 19 recordsLinked to original sources
PubMed2001

An animal model of nicotinic-acid-induced vasodilation: effect of haloperidol, caffeine and nicotine upon nicotinic acid response.

BACKGROUND: The normal vasodilatory response to ingestion of nicotinic acid (NA) is impaired in some patients with schizophrenia. It is unclear whether the impairment is a feature of the disorder itself or to a confounding factor such as neuroleptics, caffeine or nicotine use. METHODS: To address this question in a controlled manner, we have developed an animal (rat) model of NA-induced vasodilation, in which response is monitored by measuring change in skin temperature. RESULTS: We observed that (i) acute administration of acetylsalicylic acid (100mg/kg), caffeine (2.5mg/kg) and haloperidol (0.1 or 0.5mg/kg) and (ii) chronic administration of haloperidol (0.2mg/kg/day) significantly inhibited NA (30 mg/kg) response, whereas neither acute (0.25mg/kg) or chronic (0.5mg/kg/day for 14 days) administration of nicotine, or chronic administration of caffeine (5mg/kg/day for 14 days) had any significant effect upon NA response. CONCLUSIONS: Our data suggest that at least one drug commonly used to treat schizophrenia (haloperidol) can interfere with the vasodilatory response to NA. Studies using non-medicated patients with schizophrenia are required to determine whether reduced vasodilatory response to NA in schizophrenia is a feature of the disorder or a consequence of treatment.

Animals↗
PubMed1999

Clinical subtyping reveals significant differences in calcium-dependent phospholipase A2 activity in schizophrenia.

BACKGROUND: Inconsistent results in the study of phospholipid metabolism in schizophrenia may reflect the heterogeneous nature of the illness(es). Differences in patients' responses to niacin, a compound causing vasodilation via stimulation of phospholipid dependent signaling cascades, defines more homogeneous patient subgroups in which the rate limiting enzyme of this signaling pathway, phospholipase A2 (PLA2), can be studied. METHODS: Subjects were categorized as niacin-insensitive (10 schizophrenic patients and 1 control) or niacin-sensitive (13 schizophrenic patients and 29 controls). Comparisons of serum calcium-dependent PLA2 were undertaken with and without consideration of niacin sensitivity. RESULTS: Significantly more schizophrenic patients were niacin-insensitive than controls (chi 2 (1) = 12.8, p < .001). Comparison of mean serum calcium-dependent PLA2 level of all schizophrenic subjects with all healthy controls revealed no statistical difference (t(51) = .79, NS). Subtyping the schizophrenia group by niacin sensitivity/insensitivity, however, allowed significant differences to emerge (F(2,49) = 4.40, p = .018). Post-hoc tests showed the mean PLA2 activity level of niacin-sensitive subjects was lower than that of healthy subjects. CONCLUSIONS: Treatment strategies which increase calcium-dependent PLA2 activity may aid in reducing states of excess dopaminergic activity by activating second messenger systems rather than receptor blockade.

Adult↗
PubMed1998

New needle and syringe use, and use of needle exchange programmes by street recruited injection drug users in 1993.

BACKGROUND: Needle exchange programmes (NEP) provide injection drug users (IDU) with sterile injection equipment and receive used needles in exchange. In this paper we describe the use of new syringes and NEP by IDU and characteristics associated with using NEP in 1993. METHODS: Street-recruited IDU were interviewed in five US locations: Atlanta, Philadelphia, Chicago, New York City, and Los Angeles (LA) county. RESULTS: Most (75-95%) reported it was easy to get a new syringe and for their last injection, 45-77% used a new syringe and 2-18% used a syringe previously used by another IDU. Use of NEP ranged from 8% to 16% in Chicago, Philadelphia, and LA County. In LA County not having injected 'speedball' in the last 30 days, last injection with a new syringe, and reporting it was very easy to get a new syringe were associated with NEP use. In Philadelphia, NEP use was associated with 'speedball' injection in the last 30 days, and in Chicago, not injecting with 'speedball' and injecting with cocaine were associated with NEP use. CONCLUSIONS: In 1993, most street-recruited IDU in Chicago, Philadelphia, and LA County had not used NEP. Factors associated with NEP use were not consistent across sites. Dispersion of NEP and removal of legal barriers restricting access to sterile syringes may be more important in increasing the use of sterile syringes and NEP than client characteristics.

Adult↗
PubMed1995

Powerlessness, health and mortality: a longitudinal study of older men and mature women.

National samples of older men (age 45-59 in 1966) and mature women (30-44 in 1967), surveyed periodically over more than a decade, establish the association over time between the sense of powerlessness and various indices of health status (chiefly, psychosocial symptoms and limits on physical activities). The results are basically coordinate for men and women, and they are replicated for initially healthy and initially impaired sub-samples. The results show that: (1) in each year, powerlessness is associated with greater activity limits and more psychosocial symptoms; (2) powerlessness also provides prospective prediction, since high initial powerlessness scores are associated with health problems observed five and ten years later, with initial health controlled; (3) increasing powerlessness accompanies deterioration in health (with stringent controls on prior health); and (4) for a sub-sample of men, mortality between 1976 and 1981 is also associated with initially high powerlessness scores (with prior health controlled). These results are discussed for their import in relation to the steadily growing interest in social psychological factors in health.

Adult↗
PubMed1994

Dynamic external fixation of unstable fractures of the distal part of the radius. A prospective, randomized comparison with static external fixation.

A prospective, randomized study was done to compare the results of dynamic external fixation (the Clyburn device) with those of static external fixation (the AO/ASIF device) in the treatment of fifty unstable fractures of the distal part of the radius. Mobilization of the wrist from neutral to 30 degrees of flexion was begun in the dynamic-fixator group at approximately two weeks, and full motion, allowing 30 degrees of extension, was started at approximately four weeks. The external fixation frames in both groups were kept in place for approximately ten weeks. Mobilization of the wrist in the dynamic-fixator group provided little gain in the mean motion of the wrist at the time of the removal of the fixator or at the one, six, or twelve-month evaluation. The static-fixator group had greater flexion of the wrist and radial deviation at the early and late follow-up examinations, while the dynamic-fixator group demonstrated only greater ulnar deviation one month after the fixator had been removed. Motion of the wrist in the dynamic-fixator group resulted in a statistically significant loss of radial length compared with that in the static-fixator group (four millimeters compared with one millimeter, p < 0.001). Complications were more frequent in the dynamic-fixator group. As evaluated with a modification of the scoring system of Gartland and Werley, 92 percent of the results at one year were excellent or good in the static-fixator group and 76 percent, in the dynamic-fixator group. The results of this study cannot support the concept of early mobilization with a dynamic external fixator for the treatment of unstable fractures of the distal part of the radius.

Adult↗
PubMed1992

Life strains, alienation, and drinking behavior.

This paper examines the effect on drinking behavior of chronic strains deriving from on-going work circumstances, and intermittent strains deriving from transitions imposed by life events: unemployment; economic strain; and stress experience (e.g., death in the family, serious illness, etc.). The respondent's personal resources for coping with these life strains are also examined by way of three measures of alienation: the sense of powerlessness, self-esteem, and social integration. The interaction of situational strains and individual alienation is a primary focus. Regression and covariance analyses, using a sample of some 500 male respondents, indicate that (1) unemployment in itself is of relatively little consequence, (2) powerlessness is the most consistent predictor of alcohol use and abuse, and (3) the combination of stress experience and high powerlessness typifies those who are most vulnerable to high drinking quantity and drinking problems.

Adaptation, Psychological↗
PubMed1988

Anomalous motoric lateralization and schizophrenia: clinical implications.

Sixty-five schizophrenic subjects (46 men and 19 women) were tested for motor preference and compared to age and sex-matched controls. There were significantly more nondextrals among the schizophrenic women. Both male and female nondextral schizophrenics were hospitalized more frequently and for longer periods than dextral schizophrenics.

Adolescent↗
PubMed1981

In vitro characterization of the mechanism of insulin degradation and the effect of chloroquine.

The cultured rat hepatoma cell line, MH1C1, inactivates 125I-labeled insulin by a temperature dependent mechanism. The estimated Km for insulin degradation is 1.4 . 10(-7) M and the V is 2.5 . 10(-10) mol/10(6) cells/h. The iodocompounds released from cells preincubated at 0 degrees C with 125I-labeled insulin are immunoreactive with anti-insulin antibody, while the iodocompounds released from the cells incubated at 37 degrees C only reacts to a very small degree with anti-insulin antibody. The degradation products were analyzed by Sephadex gel chromatography. Sephadex G-75 gel filtration of iodocompounds derived from cells incubated at 37 degrees C with 125I-labeled insulin for 5, 20 min and 1 h showed a progressive decrease in intact insulin, and an increase in the peak representing insulin breakdown products. Treatment with chloroquine, a lysosomal enzyme inhibitor, resulted in a large increase of cell-associated insulin compared to control cells. However, chromatographic studies of iodocompounds extracted from cells incubated with or without chloroquine show a similar pattern but differ in the size of the peak which represents the degradation products of 125I-labeled insulin. Furthermore, the iodocompounds released from the chloroquine treated cells were not immunoreactive with anti-insulin antibody. These results suggest that chloroquine inhibits the release of insulin degradation products from the cells.

Animals↗