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Biomedical subjects

M Kotler

Publications and source records attributed to M Kotler.

At least 109 records · Page 6Linked to original sources
PubMed1993

Correlates of suicide and violence risk in an inpatient population: coping styles and social support.

Forty-six suicidal psychiatric inpatients were compared with 44 nonsuicidal psychiatric inpatients on measures of suicide risk, violence risk, impulsivity, feelings of anger, social support, and eight coping styles. The two groups were similar on demographic variables, but the suicidal patients were higher on the suicide risk scale, the violence risk scale, the impulsivity scale, and feelings of anger. Suicidal patients were significantly less likely to use the coping style of minimization to deal with life problems. A negative correlation was found between the social support measure and both suicide risk and violence risk. Three coping styles were found to correlate negatively with violence risk, but none with suicide risk. Coping styles were found to be a better predictor of violence risk than of suicide risk. It was also found that the more variables included in the predictor equation, the higher the correlation with the risk measures.

Adaptation, Psychological↗
PubMed1992

Suicide and violence associated with panic attacks.

Several studies have indicated that patients with panic attacks have a higher rate of suicide attempts as well as deaths from suicide. Additionally, several investigators have presented case reports of individuals manifesting suicidal and violent behaviors directly and temporally associated with panic attacks. We report on four additional cases and suggest that these findings may explain, in part, the increased rate of suicidal behavior among patients with panic attacks found by some investigators. Furthermore, these case reports offer preliminary evidence that the relationship between violent behavior and the panic state may be clinically significant and deserving of further elucidation.

Adult↗
PubMed1992

Induction of IL-4 secretion by the radiation leukemia virus (RadLV): role in autocrine growth stimulation of RadLV infected pre-leukemic cells.

Intrathymic inoculation of radiation-leukemia virus (RadLV) into C57BL/6 mice induces a population of pre-leukemic (PL) T cells which progress into clonal, mature thymic lymphomas after a latency period of 3 to 5 months. In order to understand how PL cells are retained in the thymus for a prolonged period of time we determined whether RadLV infected cells secrete and/or respond to a T-cell growth factor that may be involved in the long-term maintenance of a thymic PL-cell pool. We have previously found that in vitro proliferation of RadLV-infected PL cells is IL-4-dependent. Here we show that RadLV induces IL-4 secretion and IL-4 receptor (IL-4R) expression in normal thymic lymphocytes. RadLV-infected PL thymocytes express IL-4R and secrete IL-4. Their IL-4 secretion could be enhanced if incubated in the presence of RadLV and this enhancement was inhibited by anti-RadLV antibodies. Several RadLV-induced lymphoma lines secreted IL-4 and/or expressed IL-4R, but these features were not essential for their continuous growth. The results suggest that RadLV induces IL-4-dependent autocrine growth which maintains a population of PL T cells in the thymus. Transition from a PL state to overt thymic lymphoma involves emancipation of a PL cell from IL-4 dependency.

Animals↗
PubMed1992

Human immunodeficiency virus type 1 gag-protease fusion proteins are enzymatically active.

We have introduced mutations into the region of the genome of human immunodeficiency virus type 1 (HIV-1) that encodes the cleavage sites between the viral protease (PR) and the adjacent upstream region of the polyprotein precursor. Segments containing these mutations were introduced into plasmids, and the retroviral proteins were expressed in Escherichia coli. The mutations prevented cleavage between the PR and the adjacent polypeptide; however, other PR cleavage sites in the polyprotein were cleaved normally, showing that the release of free PR is not a prerequisite for the appropriate processing of HIV-1 precursors.

Escherichia coli↗
PubMed1992

Processing of avian retroviral gag polyprotein precursors is blocked by a mutation at the NC-PR cleavage site.

The avian sarcoma and leukosis viruses (ASLV) encode a protease (PR) at the C terminus of gag which in vivo catalyzes the processing of both gag and gag-pol precursors. The studies reported here were undertaken to determine whether PR is able to cleave these polyproteins while it is still part of the gag precursor or whether the release of its N terminus to form free PR is necessary for full proteolytic activity. To address this question, we created a mutation that disrupts the PR cleavage site between the NC and PR coding regions of the gag gene. This mutation was introduced into a eukaryotic vector that expresses only the gag precursor and into an otherwise infectious clone of ASLV that carries the neo gene as a selectable marker. These constructs were expressed in monkey COS cells or in quail QT35 cells, respectively. Processing was impaired in both systems. Mutant particles were formed, but they contained no mature processed gag proteins. We observed only the uncleaved gag precursor polypeptide Pr76 in one case or Pr76 and a cleaved product of about 60 kDa in the other. Processing of the mutant gag precursor could be complemented in trans by from a wild-type construct, suggesting that the mutation did not induce gross structural alterations in its precursor. Our results suggest that the PR first must be released from its precursor before it can attack other sites in the gag and gag-pol polyproteins and that cleavage at the NC-PR boundary is a prerequisite for the initiation of the PR-directed processing.

Amino Acid Sequence↗
PubMed1991

Quantitation, in vitro propagation, and characterization of preleukemic cells induced by radiation leukemia virus.

Intrathymic (i.t.) inoculation of radiation leukemia virus into C57BL/6 mice induces a population of preleukemic (PL) cells that can progress into mature thymic lymphomas upon transfer into syngeneic recipients. A minimum of 10(3) PL thymic cells are required to induce lymphomas in the recipient. Most of the individual lymphomas developed in mice which were inoculated with cells of a single PL thymus, derived from different T-cell precursors. PL thymic cells could be grown in vitro on a feeder layer consisting of splenic stromal cells. Growth medium was supplemented with supernatant harvested from an established radiation leukemia virus-induced lymphoma cell line (SR4). The in vitro-grown PL cells were characterized as Thy-1+, CD4+, CD8- T-cells, most of which expressed radiation leukemia virus antigens. Cultured PL cells were found to be nontumorigenic, based on their inability to form s.c. tumors. However, these cells could develop into thymic lymphomas if inoculated i.t. into syngeneic recipients. A culture of PL cells, maintained for 2 mo, showed clonal T-cell receptor arrangement. Lymphomas which developed in several recipient mice upon injection with these PL cells were found to possess the same T-cell receptor arrangement. These results indicate that PL cells can be adapted for in vitro growth while maintaining their preleukemic character.

Animals↗
PubMed1991

[Evaluating parachute-drop stress by measuring blood lipids].

An attempt to evaluate parachute-drop related stress by determining the blood lipid profile (cholesterol, LDL, HDL, apo-A, apo-B, and triglycerides) is reported. Measurements were made on starting the parachute course, just before the first jump, and just after the third jump. On these 3 occasions 38 combat troops answered psychological questionnaires and 30 of them gave blood samples. While there were significant fluctuations in level of all blood lipids and their apoproteins, they could not be correlated selectively with presumed levels of stress. The well-known difficulties in field studies in controlling crucial factors such as the exact timing of the measurements and food intake (specific diet or fasting) make questionable the use of biochemical markers in measuring stress under the conditions of our study. It is possible that the high rate of refusal to give blood samples biased the findings.

Apolipoproteins A↗
PubMed1991

Platelet peripheral benzodiazepine receptors in repeated stress.

[3H]PK 11195 binding to platelet membranes and plasma stress hormones were studied in soldiers at the beginning of a parachute training course, following 6 days of preparatory exercises, and after the fourth actual parachute jump. A slight reduction (15%; NS) in the number of peripheral benzodiazepine receptors (PBR) was detected at the end of the exercise period, prior to the first jump. Reduced (26%; P less than 0.05) density of PBR was observed immediately after the repeated actual jumps. Equilibrium dissociation constants were not affected by the stressful situation. Plasma cortisol and prolactin levels remained unaltered during the entire study period.

Adolescent↗
PubMed1991

Correlates of risk of suicide in violent and nonviolent psychiatric patients.

OBJECTIVE: This study was designed to identify variables that correlate with the risk of suicide in two patient groups that differ mainly in their level of expressed aggression. METHOD: Twenty-eight psychiatric patients with a history of violent behavior who were in a forensic psychiatric facility were tested and compared to 28 psychiatric inpatients without a history of violence who were admitted to a large municipal hospital. Measures used included a battery of self-report questionnaires, with acceptable reliability and validity, that provided indices of risk of suicide, risk of violence, impulsivity, anger, anxiety, and various mood states. RESULTS: The two groups, matched on demographic variables and overall risk of suicide, differed significantly on the measured risk of violence. The two groups showed similar patterns of correlations between risk of suicide and such variables as risk of violence, anger, fear, state and trait anxiety, lack of impulse control, suspiciousness, and rebelliousness. They differed in the correlation between suicide risk and depression. In the nonviolent patients there was a high correlation between risk of suicide and sadness; in the violent patients there was no correlation between these variables. CONCLUSIONS: The low correlation between sadness and risk of suicide in the violent patients, and the low prevalence of affective disorder diagnoses in these patients compared to other patients, suggests that suicidal risk should be managed differently in highly violent patients than in others.

Adult↗
PubMed1991

Physicians' detection of psychological distress in primary-care clinics.

This study investigated the amount of psychological distress reported by 182 soldiers in the Israeli military and compared soldiers' self-ratings of distress with ratings by military physicians of observed distress. Comparisons indicated a low detection rate by physicians with only 13% of self-reported cases of emotional distress identified. This and several related findings were taken to indicate shortcomings in medical care. Possible remedies include additional psychiatric training for military physicians, less frequent rotation of physicians to allow for more stable care, and the initiation of mental health education among soldiers.

Adult↗
PubMed1991

Measuring psychological stress in primary care military medical clinics.

In this study, the amount of psychological distress reported by soldiers is investigated and measured over time. The soldiers--enlisted and career--were randomly chosen while visiting five different military primary care clinics (for ostensible somatic problems) and administered the General Health Questionnaire (Goldberg and Huxley, 1980). A third of the subjects were given the GHQ a year later. Fifty-two percent showed psychological stress: combat soldiers showed considerably less distress than technical/maintenance and administrative soldiers, and the psychological stress findings remained relatively stable over time. Possible explanations for these findings are discussed.

Adult↗
PubMed1991

The clinical picture of acute combat stress reaction among Israeli soldiers in the 1982 Lebanon War.

This study examined 100 randomly selected medical charts of Israeli psychiatric casualties of the 1982 Lebanon War in order to determine the clinical picture of combat stress reaction as recorded by clinicians on the battlefield. We found nine categories of symptoms. The most prevalent clinical picture (48% of cases) was polymorphic, followed by anxiety (13%) and labile states (11%). Only 41% of cases were mono-symptomatic and stable. Examination of the polymorphic and labile clinical pictures revealed that the most prominent symptomatology was anxiety and depression. In the labile states, the most widespread beginning symptom was anxiety and the most prevalent end state was found to be depression. These findings are discussed in light of reports from other wars.

Adult↗
PubMed1990

Inactivation of vesicular stomatitis virus by photosensitization following incubation with a pyrene-fatty acid.

Vesicular stomatitis virus (VSV) was incubated with pyrene dodecanoic acid (P12), a fluorescent derivative of a medium-chain length fatty acid, and subjected to irradiation with a long wavelength ultra-violet light source at 366 nm (UVA). This inactivated the virus, resulting in a drastic decrease of its infectivity. The virus inactivation was proportional to the concentration of the pyrene-fatty acid, the length of exposure of the virus to P12 and the irradiation dose.

Dose-Response Relationship, Drug↗
PubMed1990

Multifocal vascular tumors in fowl induced by a newly isolated retrovirus.

The morphological features of a spontaneous, multifocal vascular neoplasm of chickens are described. Histologically, the tumor was characterized by areas consisting of freely anastomosing vascular channels with prominent papillary appearance and lined by bland-looking endothelial cells, which alternate with areas resembling cavernous hemangioma. Occasionally solid areas composed of plump, pleomorphic cells were also present. Although there was no clear evidence for metastatic spread, some tumors were obviously invasive. Electron microscopy and immunohistochemistry confirmed the endothelial nature of neoplastic cells, demonstrating in particular pinocytic vesicles, well developed junctional complexes, fragmented basal lamina, occasional Weibel-Palade bodies, and patchy factor VIII-related antigen immunoreactivity. The overall appearance of the tumor was that of a cavernous hemangioma with prominent papillary endothelial hyperplasia. Previously we have shown that the tumor was induced by a newly isolated strain of avian hemangioma retrovirus and in this study we demonstrated typical type C retrovirus particles in the tumor by electron microscopy. It is suggested that this retrovirus-induced avian tumor may serve as a useful model for the study of transformed endothelia and other vascular tumorigenesis.

Animals↗
PubMed1990

Unique sequences in the env gene of avian hemangioma retrovirus are responsible for cytotoxicity and endothelial cell perturbation.

An avian retrovirus isolated from spontaneous cavernous hemangiomas of layer hens codes for an env protein that induces a cytopathic effect on a wide variety of cultured avian and mammalian cells and also causes thrombogenicity of endothelial cells. Sequence analysis of the avian hemangioma inducing virus revealed unique elements in both its env gene and its LTR. We propose that these elements are responsible for the biological and pathogenic characteristics of the virus.

Amino Acid Sequence↗
PubMed1990

Envelope glycoprotein of avian hemangioma retrovirus induces a thrombogenic surface on human and bovine endothelial cells.

Vascular endothelial cells are a target for blood-borne pathogens which may affect their integrity and thromboresistant properties. Here, we report that cultured bovine and human endothelial cells lose their thromboresistance following interaction with the avian hemangioma-inducing retrovirus. We show that the envelope (env) gene product, glycoprotein 85, is responsible for this effect, which appears soon after infection without viral replication or cell transformation. Induction of thrombogenicity is associated with a reduction in prostacyclin release and increased expression of tissue factor. These observations may explain the occurrence of thrombosis frequently observed in association with the hemangiosarcomas induced by avian hemangioma-inducing retrovirus. These unique endothelial cell-virus interactions may also be a model for the pathogenesis of various vascular diseases.

Animals↗