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Biomedical subjects

M Cohen

Publications and source records attributed to M Cohen.

At least 883 records · Page 49Linked to original sources
PubMed1981

Baboon endogenous virus genome: molecular cloning and structural characterization of nondefective viral genomes from DNA of a baboon cell strain.

Several heterogeneities in the baboon endogenous virus (BaEV) genomes that are present in the DNA of normal baboon tissues and the baboon cell strain BEF-3 have been described previously. To study these genomes, we cloned BaEV proviruses from BEF-3 cellular DNA into the lambda vector Charon 4A. Of the four full-length clones isolated, one was nondefective as determined by transfection. The sequence of a portion of this clone was found to code for amino acids 61-91 in the p30 region of the gag gene. This identification allowed us to align the restriction map with the BaEV genetic map. One heterogeneity, a BamHI site 2.4 kilobases (kb) from the proviral 5' end, was located close to the gag-pol junction; another, a BamHI site 1.4 kb from the 5' end of the genome, corresponded to the gag p30 coding sequence for amino acids 32-34; and a third, a Xho I site, was near the 3' end of the pol gene. To select the nondefective BaEV genomes from BEF-3 cells, we infected permissive cells with virus produced by BEF-3 cells and also transfected BEF-3 cellular DNA into permissive cells. The BaEV genomes in the permissive recipient cultures were then analyzed by restriction enzyme analysis. These nondefective genomes were found to be heterogeneous with respect to the gag-pol BamHI site and the Xho I site, but all were found to contain the BamHI site 1.4 kb from the 5' end of the genome.

Animals↗
PubMed1981

Abortion on demand: policy and implementation.

The roots of the controversy over abortion lie deep in the social, moral, and religious norms of American society. The authors trace these roots and analyze the policy implications of recent Supreme Court decisions on abortion. They argue for a strong social work commitment to making abortion an accessible alternative for all women in the United States.

Abortion, Legal↗
PubMed1981

Computed tomography of cerebral syphilis.

The computed tomographic findings in two patients with clinical and laboratory evidence of neurosyphilis are reported. Two patterns were described, one with pronounced lucency of the white matter and the other with multiple infarctions of unusual distribution.

Aged↗
PubMed1981

Does progressive pancreatic insufficiency limit pain in calcific pancreatitis with duct stricture or continued alcohol insult?

We studied the pancreatic function, alcohol history, and ERCP findings in 26 patients with painless and 34 patients with painful alcohol-induced calcific pancreatitis (AICP). About 50% of patients in both the painless and painful groups continued to take alcohol, the incidence of duct stricture or obstruction was of the order of 62% in both groups, and the proportion of patients with duct stricture or obstruction and continued alcohol intake was comparable. In all instances the patients in the painless category had significantly greater pancreatic insufficiency, or more impaired function, than patients with pain. This applied to those patients who continued to take alcohol, to those with an obstruction or stricture on ERCP, and to the subgroup with both duct narrowing and continued alcohol intake. We conclude that grossly impaired pancreatic function confers a degree of freedom from painful attacks in AICP in those patients who continue to drink even in the presence of duct obstruction or stricture on ERCP; and that patients with AICP become free of pancreatic pain once gross pancreatic insufficiency supervenes.

Alcoholism↗
PubMed1981

Efficacy of whole lung tomography in diagnosing metastases from solid tumors in children.

Whole lung, frontal tomography is compared with frontal chest radiography in the diagnosis of pulmonary metastasis in children with cancer. Of 79 patients studied, 65 had a total of 195 routine tomograms. In only 2.7% of studies did tomography yield new information, and in only 1% was an additional lesion visualized. In 27 patients, tomography was performed after an abnormality was seen on the chest radiograph. New information was obtained in 15 (32%) of those 47 studies; additional nodules were identified on six occasions (four metastatic, two inflammatory), but only once was treatment altered. In one study, tomography localized a nodule seen only on a lateral chest radiograph, and in eight studies it excluded metastasis following an abnormal frontal chest radiograph.

Adolescent↗
PubMed1981

Period of risk hypothesis after prophylactic radiotherapy.

A critical review is given of the period of risk hypothesis (Collins's law) in regard to treated medulloblastoma. Exceptions to the law are seen to be of two types. The first type involves recurrence of the primary tumor, either local or disseminated, and is normally observed close to the limit of the risk period. The second type usually presents a malignant astrocytoma at a considerable multiple of the risk period. The relevant pathological and cellular kinetic data are reviewed to answer the question whether glial tumor recurrence is due to dedifferentiation of the primary cell line or is secondary to the therapeutic irradiation.

Brain↗
PubMed1981

The dexamethasone suppression test as a measure of hypothalamic-pituitary feedback sensitivity and its relationship to behavioral arousal.

A nonhuman primate model was used to evaluate the value of the dexamethasone suppression test as an index of hypothalamic-pituitary-adrenal responsiveness to arousal. In 8 rhesus monkeys plasma cortisol was suppressed by dexamethasone in a dose-dependent fashion at doses between 0.75 and 33 microgram/kg. A replication study was performed 5 months later using a single dexamethasone dose (17 microgram/kg) known to produce maximal plasma cortisol suppression. This yielded highly correlated results (r = 0.91, p less than 0.005) suggesting that dexamethasone suppressibility may be a stable characteristic of individual animals. In 9 other animals whose arousal responses to a stressful procedure (nasogastric tube insertion) had been rated daily over a previous 3-month period, baseline plasma cortisol levels and the percent suppression of plasma cortisol by dexamethasone were evaluated. Baseline plasma cortisol levels did not significantly correlate with the degree of dexamethasone-suppression and the mean arousal ratings within animals. However, the postdexamethasone percent of baseline cortisol did correlate significantly (r = 0.75, p less than 0.025) with individual mean arousal ratings. These preliminary results suggest that assessment of the sensitivity of an individual's hypothalamic-pituitary glucocorticoid feedback system may be a better predictor than its baseline cortisol concentrations of its degree of behavioral arousal to stress.

Animals↗
PubMed1981

Symmetric sarcoid polyneuropathy: analysis of a sural nerve biopsy.

A 20-year-old woman with sarcoidosis had uveitis, subacute symmetric sensorimotor neuropathy, and noncaseous granulomas in biopsies of gastrocnemius muscle and sural nerve. Morphologic studies of the nerve confirmed the electrodiagnostic impression of an acute axonal and demyelinating neuropathy. Of 100 teased myelinated nerve fibers, 15% contained myelin ovoids and 24% demonstrated segmental demyelination. Quantitative analysis showed a reduction in the numerical density of myelinated fibers. By electronmicroscopy, unmyelinated fibers were largely spared. The exact mechanism of nerve fiber damage was not determined, but a local effect of the granuloma seemed likely, because most lesions were found in the endoneurium.

Adult↗
PubMed1981

Melatonin inhibition and pinealectomy enhancement of 7,12-dimethylbenz(a)anthracene-induced mammary tumors in the rat.

The effects of the pineal hormone, melatonin, and of pinealectomy on the incidence of mammary adenocarcinoma in Sprague-Dawley rats treated with 7,12-dimethylbenz(alpha)-anthracene (DMBA) were investigated. Melatonin (2.5 mg/kg), begun on the same day as DMBA (5 mg) treatment and given daily in the afternoon for 90 days, significantly reduced the incidence of mammary tumors from 79% (control) to 20% (treated) (p less than 0.002). Rats pinealectomized at 20 days of age and treated with 7 mg of DMBA at 50 days of age had a higher incidence of tumors (88%) compared to control animals (22%). Fifteen mg of DMBA, which resulted in a higher incidence of tumors, reduced the difference between pinealectomized and control animals. Melatonin only partially reversed the effects of pinealectomy, reducing the incidence from 87% (pinealectomy alone) to 63% (pinealectomy plus melatonin); however, the tumor incidence was still lower (27%) in nonpinealectomized, melatonin-treated animals. Assessment of plasma prolactin, luteinizing hormone, follicle-stimulating hormone, estradiol, and cortisol in DMBA-treated tumor-free and tumor-bearing animals revealed a significantly lower plasma prolactin concentration [27 +/- 5 (S.E.) ng/ml] in melatonin-treated animals as compared to vehicle-treated animals [65 +/- 8 ng/ml]. The concentration of plasma prolactin was less in melatonin-treated, pinealectomized rats (55 +/- 10 ng/ml) as compared to vehicle-treated, pinealectomized animals (101 +/- 13 ng/ml). Other hormones were not affected by melatonin treatment. These data support the hypothesis that melatonin inhibits the development of DMBA-induced mammary tumors in the rat while removal of the pineal gland stimulates development of such tumors. Additionally, these experiments provide evidence that these effects may be mediated by a suppression of plasma prolactin levels.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

Effects of orally administered psychotropic drugs on dog conditioned avoidance responses.

Orally administered haloperidol, chlorpromazine, thioridazine, clozapine, and diazepam blocked a conditioned avoidance response in male beagle dogs. All compounds except diazepam also inhibited escape behavior. Avoidance blocking does of haloperidol, chlorpromazine, and thioridazine in dogs were similar o human therapeutic dosage ranges for these drugs. The usefulness of shock avoidance by dogs as a predictor of human dosage and side effects for major tranquilizers is discussed.

Administration, Oral↗