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Biomedical subjects

R Cohen

Publications and source records attributed to R Cohen.

At least 433 records · Page 24Linked to original sources
PubMed1987

Organization of and access to semantic memory in aphasia.

Previous experiments with picture sorting and matching tasks have shown aphasics to give more deviant responses than controls when decisions require the identification of single features of concepts, whereas their responses are close to normal whenever decisions have to be based on the relative overlap of broad associative fields. The present experiment was designed to compare picture matching based on single features (property verification) with picture matching based on category membership (category verification). Fifty-five aphasics (14 amnesics, 18 Brocas, 13 Wernickes, 10 global aphasics) and 29 right-brain-damaged control patients served as subjects. Aphasics were poorer than right hemisphere controls on property as well as on category sortings, especially when the sorting criterion was not a dominant property of the object or when the object in question was not a typical member of the criterion category. Contrary to other studies, the "semantic distance" variable did not differentially affect Brocas as compared to Wernickes aphasics. Verbal labels denoting the sorting criterion and added to the picture presentation did not affect the performance of the right hemisphere controls but significantly improved that of the aphasics.

Aphasia↗
PubMed1987

Impact of time estimation on the crossover effect in schizophrenia.

To test the role of time estimation in the crossover effect (COE), reaction times (RTs) of schizophrenic, alcoholic, and normal subjects were collected in two conditions: a standard visual RT task with different preparatory intervals in regular or irregular series, and a time information condition with the intervals filled by a visual countdown analogue. In the standard condition, the COE was found not only for schizophrenics but also for alcoholics. Time information reduced RTs in all groups, but not the average COE in schizophrenics. The relationship between RTs and simultaneously collected event-related potentials was examined.

Adult↗
PubMed1987

Memory for spatial and temporal order in aphasics and right hemisphere damaged patients.

Sets of five photographs per item were presented successively in five vertically arranged frames to 53 aphasics, 27 right hemisphere damaged (RHD) patients and 18 normal subjects. Following the presentation of the five slides subjects were given a spatial and a temporal recognition task. In the spatial task subjects had to indicate which of two pictures of a probe had been nearer to the top of the vertically arranged set of frames. In the temporal task they had to indicate which of the two pictures of the probe had been presented earlier. Aphasics made significantly more errors than RHD and normals in both the spatial and the temporal task, while RHD were significantly impaired in comparison to the normal controls only in the spatial task.

Adult↗
PubMed1987

Social network ties and mortality among the elderly in the Alameda County Study.

Seventeen-year mortality data from the Alameda County Study are used to examine the relative importance of social ties as predictors of survival at different ages, ranging from 38-94 years at baseline. Previous analyses of Alameda County data by Berkman and Syme (Am J Epidemiol 1979;109:186-204) have shown that such ties are significant predictors of lower nine-year mortality risk for persons aged less than 70 years at baseline. Proportional hazard analyses indicate that social ties are also significant predictors of lower 17-year mortality risks for those aged 70 and older after adjusting for age, sex, race, baseline health status, perceived health, depression, and health practices (relative hazard = 1.49 for Berkman-Syme Social Network Index; 95% confidence interval (CI) = 1.09-2.05). Comparisons of the relative importance of four types of social ties reveal an interesting shift across the age groups. Marital status assumes primary importance for those aged less than 60 years at baseline (relative hazard = 1.6 and 1.4 for those aged 38-49 and 50-59, respectively; 95% CI = 1.12-2.29 and 1.02-1.91, respectively). However, ties with close friends and/or relatives assume greater importance for those aged 60 and older (relative hazard = 1.17 comparing those reporting five or more contacts per month to the more socially isolated who report less than five such contacts per month; 95% CI = 0.98-1.89).

Adult↗
PubMed1987

Transcription of the constitutively expressed yeast enolase gene ENO1 is mediated by positive and negative cis-acting regulatory sequences.

There are two enolase genes, ENO1 and ENO2, per haploid yeast genome. Expression of the ENO1 gene is quantitatively similar in cells grown on glucose or gluconeogenic carbon sources. In contrast, ENO2 expression is induced more than 20-fold in cells grown on glucose as the carbon source. cis-Acting regulatory sequences were mapped within the 5'-flanking region of the constitutively expressed yeast enolase gene ENO1. A complex positive regulatory region was located 445 base pairs (bp) upstream from the transcriptional initiation site which was required for ENO1 expression in cells grown on glycolytic or gluconeogenic carbon sources. A negative regulatory region was located 160 bp upstream from the transcriptional initiation site. Sequences required for the function of this negative regulatory element were mapped to a 38-bp region. Deletion of all or a portion of these latter sequences permitted glucose-dependent induction of ENO1 expression that was quantitatively similar to that of the glucose-inducible ENO2 gene. The negative regulatory element therefore prevents glucose-dependent induction of the ENO1 gene. Hybrid 5'-flanking regions were constructed which contained the upstream regulatory sequences of one enolase gene fused at a site upstream from the TATAAA box in the other enolase gene. Analysis of the expression of enolase genes containing these hybrid 5'-flanking region showed that the positive regulatory regions of ENO1 and ENO2 were functionally similar, as were the regions extending from the TATAAA boxes to the initiation codons. Based on these studies, we conclude that the negative regulatory element plays the critical role in maintaining the constitutive expression of the ENO1 structural gene in cells grown on glucose or gluconeogenic carbon sources.

Amino Acid Sequence↗
PubMed1987

Acromegaly due to a growth hormone-releasing hormone-secreting bronchial carcinoid tumor: further information on the abnormal responsiveness of the somatotroph cells and their recovery after successful treatment.

UNLABELLED: We studied GH secretion in a patient with acromegaly and a bronchial carcinoid tumor before and again after surgical removal of this tumor. Before removal of the carcinoid tumor, plasma GH increased slightly after glucose loading (OGTT) and markedly after TRH (650%) and insulin (440%) treatment. Plasma GH did not change after GH-releasing hormone (GHRH), LHRH, or L-dopa administration. Somatostatin (SRIH) infusion lowered plasma GH. No change in plasma immunoreactive GHRH (IR-GHRH) occurred after TRH, glucose, insulin, or SRIH administration. Two weeks after removal of the carcinoid tumor, TRH induced GH secretion (250%) when the IR-GHRH level was undetectable and somatomedin-C was within normal limits. Fifteen weeks after surgery, the patient had normal GH secretion. IN CONCLUSION: no pattern of GH secretion is diagnostic of acromegaly due to ectopic GHRH secretion, but the lack of GH response to exogenous GHRH and a large response during hypoglycemia may be features of this condition. When acromegaly and abnormal GH responsiveness are induced by a GHRH-secreting tumor, the increases in plasma GH after TRH, glucose, and insulin administration are not mediated by GHRH. After removal of the GHRH-secreting tumor, persistent paradoxical GH response to TRH does not require abnormally high IR-GHRH levels and does not preclude complete recovery.

Acromegaly↗
PubMed1987

Effect of epinephrine on the relationship between nonesterified fatty acid availability and ketone body production in postabsorptive man: evidence for a hepatic antiketogenic effect of epinephrine.

The effect of epinephrine (EPI) on the transformation of nonesterified fatty acids (NEFA) into ketone bodies (KB) in normal subjects was determined by measuring simultaneously NEFA ([1-13C]palmitic acid) and KB ([3-13C]- or [3,4-13C2]acetoacetate) kinetics at different NEFA levels in the presence of basal (control test) or increased (EPI infusion test) EPI concentrations. During the control test the initial (postabsorptive state) concentrations and turnover rates of NEFA and KB were 476 +/- 47 (+/- SEM) and 4.30 +/- 0.17 mumol kg-1 min-1 (NEFA) and 126 +/- 17 and 2.49 +/- 0.07 mumol kg-1 min-1 (KB). The fraction of NEFA converted into KB was between 11.5-14.6%. Raising NEFA levels to about 650 mumol L-1 (iv infusion of a triglyceride emulsion) resulted in an increase in this fraction to between 26-30.3% (P less than 0.01). When NEFA concentrations were next abruptly raised to high levels (near 3 mmol L-1) by heparin injection this fraction returned to near the initial values (15-19.2%). During the EPI infusion test the initial (postabsorptive) concentrations and turnover rates of NEFA and KB as well as the fraction of NEFA converted into KB (10.5-11.5%) were comparable to the initial values of the control test. Intravenous infusion of EPI (10 ng kg-1 min-1) raised NEFA between 600 and 750 mumol L-1, comparable to values during the triglyceride test, but the fraction of NEFA converted into KB remained between 8.2-12% (P less than 0.05 vs. control test); when NEFA then were raised to even higher values (near 2.5 mmol L-1) by the infusion of a triglyceride emulsion and the injection of heparin, this fraction decreased to between 4-8% (P less than 0.05 vs. initial values of the EPI test and P less than 0.05 vs. the control test). In conclusion, 1) the fraction of NEFA converted into KB appears to depend in part on the NEFA concentration; and 2) the net effect of EPI infusion was to decrease the fraction of NEFA converted into KB.

Absorption↗
PubMed1987

Dementia of the Alzheimer type: clinical and family study of 22 twin pairs.

We studied 22 twin pairs in which one or both twins had dementia of the Alzheimer type (DAT). In four twins, diagnosis was confirmed by autopsy. Seven monozygotic (MZ) pairs were concordant for DAT; 10 MZ pairs were discordant. Two dizygotic (DZ) pairs were concordant for DAT, and 3 DZ pairs were discordant. The current concordance rate was 41% for MZ twins and 40% for DZ twins. The study supports the belief that, etiologically, DAT cannot be entirely accounted for by a single autosomal dominant gene. The data also suggest that in certain genetic circumstances, disease expression may be delayed in females.

Aged↗
PubMed1987

Bronchial response to methacholine in parents of asthmatic children.

Cumulative dose response curves to inhaled methacholine were established in 28 parents of asthmatic children, seven parents of healthy children, and four asthmatic patients. Bronchial sensitivity was defined as the dose of methacholine causing a 25 percent decrease in specific airway conductance while bronchial reactivity was determined by the slope of the cumulative dose response curve. Results indicated that parents with allergic rhinitis or airflow limitation in small airways may represent a high risk group, while parents with no atopy and normal pulmonary functions may reflect only the inherited characteristics of bronchial response.

Adolescent↗
PubMed1987

A comparative study of lactogenic hormone binding sites in the adrenal gland, ovary and kidney of the lactating cow.

The specific binding of 125I-oPRL to microsomal fractions from the adrenal gland, ovary and kidney of the lactating cow was significantly lower than binding of iodinated hGH. In addition, the ability of oPRL to compete with iodinated hGH as compared to hGH, was 50-fold lower in the adrenal gland 35-fold lower in the ovary and 18-fold lower in the kidney. These results are similar to those obtained in the mammary gland and liver, whereas the ability of oPRL to compete with iodinated hGH was 90-fold lower, as compared to hGH. In the kidney the difference between the binding of iodinated hGH and iodinated oPRL was smaller. Results obtained with a solubilized kidney microsomal fraction also show a slightly higher affinity for oPRL than in other tissues. Thus the phenomena of differential affinities of oPRL and hGH to lactogenic hormone binding sites, characterizes most lactogenic hormone target tissues in the lactating cow. The distribution of these sites in different parts of the tissues was also studied. In the adrenal gland, the binding capacity in the cortex was 8-fold higher than in the medulla. In the ovary most of the binding sites were found in the corpus luteum, while in the kidney the binding capacity was higher in the cortex as compared to the medulla.

Adrenal Glands↗
PubMed1987

[Autoimmune neutropenia disclosing AIDS in a child].

A 15 month old child with a history of multiple infectious diseases was admitted to hospital for investigation of pyrexia and general ill health. She was anaemic with a persistent neutropaenia associated with hypergamma globulinemia, indicating intense autoimmune activity: cellular immunity was abnormal with a normal total lymphocyte count but a very low T4/T8 ratio. HIV serology was positive; the virus was isolated from a lymph node biopsy specimen. The parents for the child were HIV positive and the father went on to develop full blown AIDS. The neutropaenia was constant over the two years of follow-up and granulo-immunofluorescence studies suggested an autoimmune origin. In contrast to autoimmune thrombocytopaenia and haemolytic anaemia, autoimmune neutropaenia is a rare condition. A few cases have been reported in adult AIDS. Our case is of additional interest as it illustrates the vertical mode of transmission of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1987

[Vacation for schizophrenic patients from inpatient treatment--stress for relatives].

A sample of 45 schizophrenic (DSM-III) inpatients was used to investigate which types of behavior were experienced by family members during the first weekend leave as an emotional strain, and how this strain relates to the patients' symptoms. No type of behavior predominated in being found particularly disturbing: the strain was distributed evenly over all pathological behaviors. Estimation of pathological symptoms by nursing staff and therapists immediately before weekend leave did not predict the emotional load on family members. These results lead to the recommendation that patients' behavior on a psychiatric ward should not be used to make broad predictions about difficulties that will be experienced in family relationships. A better judgment will be obtained by sending patients home for trial periods and holding subsequent discussions with family members as well as patients.

Adaptation, Psychological↗
PubMed1986

Determination of human ketone body kinetics using stable-isotope labelled tracers.

In order to avoid the use of radioactive tracers for the determination of human ketone body turnover, we have developed a method using a primed-continuous infusion of 13C-labelled acetoacetate or D-beta-hydroxybutyrate. Determination of the mole percent enrichment of blood acetoacetate and D-beta-hydroxybutyrate was performed by gas chromatography/mass spectrometry. In the post-absorptive state, the mean total ketone body appearance rate, determined in four subjects, was 3.74 mumol X kg-1 X min-1 using [3,4-13C2] acetoacetate and 2.76 mumol X kg-1 X min-1 using [3-13C]D-beta-hydroxybutyrate, values in agreement with those reported in studies with 14C-labelled tracers. In order to evaluate the usefulness of the method for determination of ketone body kinetics in non steady-state conditions, we infused four subjects with natural sodium acetoacetate and calculated the isotopically determined total ketone body appearance rate using a single compartment model (volume of distribution 0.20 l/kg; functional pool fraction: 1). During the tests with [3,4-13C2]-acetoacetate, the actual infusion rates of natural acetoacetate were 7.3 +/- 0.3, 14.6 +/- 0.8, 21.9 +/- 1.2 and 10.9 +/- 0.6 mumol X kg-1 X min-1 whereas the corresponding isotopically determined total ketone body appearance rates were respectively 9.2 +/- 1.0, 16.3 +/- 0.7, 23.1 +/- 1.1 and 10.7 +/- 0.8 mumol X kg-1 X min-1. During the tests with [3-13C]D-beta-hydroxybutyrate, the actual infusion rates were 8.4 +/- 0.5, 16.8 +/- 0.9, 25.2 +/- 1.4 and 12.6 +/- 0.8 mumol X kg-1 X min-1, and the isotopically determined appearance rates respectively 11.1 +/- 0.7, 16.7 +/- 0.7, 25.0 +/- 1.1 and 11.1 +/- 0.7 mumol X kg-1 X min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗