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Biomedical subjects

R Cohen

Publications and source records attributed to R Cohen.

At least 523 records · Page 29Linked to original sources
PubMed1983

Simultaneous treatment of the wife in infertile couples with oligospermia.

Poor ovulation was found to be common in infertile couples with oligospermia. When the sperm count was less than 5 x 10(6)/ml, 33% of wives had poor ovulation. When the sperm count was between 5 x 10(6)/ml and 20 x 10(6)/ml, 78% of wives had poor ovulation. Improvement in sperm count was most likely to increase the chances of conception when the pretreatment sperm count was less than 5 x 10(6)/ml. Pregnancy in infertile couples with oligospermia cannot be related simply to treatment or improvement in the husband's oligospermia but can only be viewed in the context of the wife's fertility, which is quite frequently also impaired in infertile couples with male factor problems.

Clomiphene↗
PubMed1983

[A program for the care of relatives of schizophrenic patients].

The present paper gives a description of a research project which tries to evaluate the significance of family support in reducing relapse rates in schizophrenic patients. Two different forms of support for relatives are compared, a discussion group and an approach furnishing a behavior training in addition. The report is supplemented by depicting some key conditions which should be taken into consideration when establishing a support system for relatives in a Mental State Hospital. This account is based on the data of 35 patients and 62 meetings with relatives collected during the pilot phase of the project.

Adult↗
PubMed1982

Sexual agglutinins from the Chlamydomonas flagellar membrane. Partial purification and characterization.

Chlamydomonas sexual agglutinins have been quantitatively extracted from isolated flagella in vitro using the dialyzable nonionic detergent octyl-D-glucopyranoside and from cells in vivo with 12.5 mM EDTA. Both preparations elicit normal sexual responses from gametes of complementary, but not like, mating types. Extracts of vegetative cells and several agglutination-deficient (imp) mutants are totally inactive. Agglutinin activity is sensitive to trypsin, mild periodate oxidation, and heating at 60 degrees C for 1 min. These findings, coupled with the size of the molecule (it is excluded from Sepharose 6B and sediments as a 12 S particle in sucrose gradients) lead us to propose that the Chlamydomonas sexual agglutinins are large glycoproteins or glycoprotein aggregates which associate with the flagellar membrane in an extrinsic fashion. Partial purification of in vivo 125I-surface labeled EDTA extracts rules out several surface polypeptides, including the bulk of material migrating in the region of the major membrane glycoprotein (Mr 350,000), as agglutinin candidates and indicates that the active molecule is a minor component of the flagellar membrane. In addition, in vitro assays suggest a mechanism for in vivo sexual agglutination whereby stable adhesion is achieved by the active redistribution of agglutinins to the flagellar tips.

Agglutinins↗
PubMed1982

Hydrolysis of monomolecular layers of synthetic sphingomyelins by sphingomyelinase of Staphylococcus aureus.

The enzymic hydrolysis of three synthetic sphingomyelins, spread as monomolecular films at the air/water interface by purified Staphylococcus aureus sphingomyelinase was studied. Each of the three sphinomyelins (DL-erythro-N-palmitoyl-, -N-stearoyl- and -N-lignoceryl-sphingosylphosphocholine) has an optimal activity-dependent surface pressure or concentration curve. The optimal surface pressure as well as the optimal surface density for hydrolysis was different for each of the three substrates. This optimum coincides with the liquid-condensed/liquid-expanded phase transition for each of the sphingomyelins. At initial surface pressures (pi 0) below the optimum, reaction rates are controlled mainly by surface density of the substrate; above the optimal pi 0, reaction rates decrease with increasing surface pressure. The difference between the three synthetic sphingomyelins are explained by the variation in the degree of asymmetry between their two paraffinic chains.

Hydrolysis↗
PubMed1982

Trail Making Test and visual search.

The performance in the Trail Making Test (Form A) was correlated with a variety of verbal and nonverbal tests in 5 groups of patients: Broca's aphasics (N = 18), Wernicke's aphasics (N = 19) and nonaphasic patients with right hemisphere (N = 20), left hemisphere (N = 17) or diffuse (N = 18) lesions. Correlations with the Trail Making Test were found for two tests, both requiring visual search. The "Objects Finding Test" in which the target varies from item to item showed high correlations for all groups of patients. The "Hidden Patterns Test", in which the target is kept constant, correlated only on the groups of nonaphasic patients. It is concluded (1) that visual search, as tested here, is not restricted to lateralized cortical functions, and (2) that the performance in the Trail Making Test depends largely upon processes involved in visual search of varying targets.

Adult↗
PubMed1982

Cognitive impairments of aphasics in picture sorting and matching tasks.

On the basis of earlier experiments showing a differential deficit of aphasics in picture sorting and matching tasks, two experiments were conducted to test the conjecture of a specific deficit of aphasics in the analytical appraisal of individual features. Broca's and Wernicke's aphasics--according to clinical diagnoses and the Aachener Aphasie Test--were compared with patients having right-hemisphere lesions or left-hemisphere lesions without aphasia. Both groups of aphasics differed from the control groups in the sorting task, irrespective of the sorting criterion, but the differences were small. The picture matching task did not discriminate between groups. Obviously, the basic assumption has to be modified with respect to specific conditions of task requirements. The experimental literature is reviewed.

Aphasia↗
PubMed1981

Referent communication of chronic schizophrenics and chronic alcoholics under simultaneous and successive task presentation.

Sixteen chronic schizophrenics and 16 chronic alcoholics were presented pairs of colors with the instruction to describe one of them (referent) so that an unknown listener could distinguish the referent from the other color (nonreferent). In one experimental condition patients were asked to name the nonreferent before they were instructed to describe the referent (successive presentation). In the other condition a parallel set of display colors was presented simultaneously with the instruction to describe the referent. Both groups of patients communicated equally well under both modes of presentation. In both groups communication accuracy decreased while response latency and references to the nonreferent increased, the more difficult the colors were to discriminate. Schizophrenics, but not alcoholics, referred more often to both the colors in a display if the successive mode of presentation was administered before the simultaneous mode. They showed a steeper slope of utterance length across levels of difficulty than the alcoholics. In the schizophrenic group, the degree of general psychopathology as well as paranoid and anergic tendencies correlated negatively with communication accuracy, utterance length, and the number of descriptions referring to both colors of an item in the simultaneous presentation condition. Results were discussed with respect to earlier work with Cohen's (1978a) referent communication task.

Adult↗
PubMed1981

Assessing pharmacologically induced dopamine receptor sensitivity changes with the Ungerstedt turning model.

Rats were lesioned unilaterally in the substantia nigra with 6-hydroxydopamine. Turning in response to apomorphine and amphetamine was assessed before and 5 days after 3-week treatment with haloperidol. After haloperidol withdrawal, contralateral turning, measured at 5 min following IP injection of 1 mg/kg apomorphine, was significantly less than before haloperidol treatment and ipsilateral turning, measured at 30 min following IP injection of 2 mg/kg amphetamine, was significantly greater than before the haloperidol treatment. These results suggest that dopamine receptor sensitivity increased on the unlesioned side compared to the lesioned side.

Amphetamine↗
PubMed1981

Purification and properties of two distinct groups of ADH isozymes from Chinese hamster liver.

Two major classes of alcohol dehydrogenase isozymes have been purified from Chinese hamster liver. The two isozyme classes have the same subunit molecular weights but different electrophoretic mobilities. They have a similar range of substrates but different KROM values and sensitivities to the inhibitor pyrazole. The ADHs are immunologically related as determined by Ouchterlony double diffusion experiments. These results suggest that the isozymes are encoded by different structural gene loci derived from a common ancestral gene.

Alcohol Oxidoreductases↗
PubMed1981

Importance of cholesterol-phospholipid interaction in determining dynamics of normal and abetalipoproteinemia red blood cell membrane.

Acanthocytic red blood cells in patients with abetalipoproteinemia have a decrease membrane fluidity that is associated with increased sphingomyelin/phosphatidylcholine (SM/PC) ratios. Here we describe studies designed to gain better insight into (i) the interrelationship between the composition of lipoprotein and red blood cell membrane in abetalipoproteinemia patients and normal controls; and (ii) how the differences in lipid composition of the red blood cell membrane affect its fluidity. The increased SM/PC ratio found in abetalipoproteinemia plasma high density lipoproteins (HDL) (3 times greater than controls) was paralleled by an increase in this ratio in acanthocytic red cells, but to a lesser degree (almost twice greater than control red cells). Cholesterol/phospholipid mole ratios (C/P) were increased 3-fold in abetalipoproteinemia HDL, but only slightly increased in red cells compared to controls values. As in the controls, 80-85% of abetalipoproteinemia red cell sphingomyelin was found to be in the outer half of the erythrocyte membrane. Membrane fluidity was defined in terms of microviscosity (eta) between 5 and 42 degrees C by the fluorescent polarization of 1,6-diphenylhexatriene (DPH) present in erythrocyte ghost membranes. At all temperatures, membrane microviscosity was higher in abetalipoproteinemia ghosts than controls, but these differences decreased at higher temperatures (12.34 vs 9.79 poise, respectively at 10 degrees C; 4.63 vs 4.04 poise at 37 degrees C). These differences were eliminated after oxidation of all membrane cholesterol to cholest-4-en-3-one by incubation with cholesterol oxidase. Following cholesterol oxidation, the membrane microviscosity decreased in patient ghosts more than in normal red blood cells so that at all temperatures no significant differences were present relative to control ghosts, in which the apparent microviscosity was also diminished but to a lesser degree. Therefore, although increased SM/PC ratios in abetalipoproteinemia may be responsible for decreased erythrocyte membrane fluidity, these effects are dependent upon normal interactions of cholesterol with red cell phospholipid.

Abetalipoproteinemia↗
PubMed1981

Facets of analytical processing in aphasia: a picture ordering task.

Aphasics, especially those diagnosed as Broca's, have more difficulties than patients will right hemisphere lesions when required to order six pictures on the basis of a single feature delineated by the extremes of the rank-order. Additional analyses indicate that they tend also to perform worse than patients with diffuse injuries and than patients with left hemispheric lesions without aphasia. Differences are more pronounced when the critical features have to be inferred from the depicted objects (e.g. age of persons) than when they can be seen directly in the drawings (e.g. girth of persons). The performance of the aphasics correlated significantly with word comprehension scores but negligible with the Token Test. Results are discussed with respect to analytical functions differentially impaired in aphasia.

Adult↗