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Biomedical subjects

C M Clark

Publications and source records attributed to C M Clark.

At least 127 records · Page 7Linked to original sources
PubMed1987

Who provides patients with drug information?

One hundred and fifty four patients were interviewed to determine the type and source of information that they had received about drugs that had been prescribed for them. Most had been told how often to take the drugs (145 (94%)) and how much to take each time (143 (93%)), but few had been informed about side effects (49 (32%)) and fewer had received written information (22 (14%)). Pharmacists most commonly supplied information about how often to take the drugs (105 (68%)), how much to take each time (99 (64%)), and the best way to take it (109 (71%)). Doctors most often gave information about duration of treatment (116 (75)) and possible side effects (126 (82%)). Few patients requested specific information on their own initiative. More research is needed to determine how best to communicate drug information to patients.

Drug Information Services↗
PubMed1986

A differential effect of the Walker 256 carcinoma on the tyrosine protein kinase activity of liver plasma membrane domains.

Protein kinase activity was investigated in plasma membrane fractions enriched in either sinusoidal or lateral domains prepared from liver of normal rats and rats bearing a Walker 256 carcinoma. Membrane proteins were phosphorylated on tyrosine, threonine and serine residues in both fractions. Phosphorylation of tyrosine residues was increased in sinusoidal preparations from tumour-bearing rats but not in lateral preparations. An increase in histone phosphorylation by sinusoidal preparations from tumour-bearing rats was found to be due to serine protein kinase activity.

Animals↗
PubMed1986

Regression model for predicting dissociations of regional cerebral glucose metabolism in individuals at risk for Huntington's disease.

This article describes and partially validates a method for predicting whether an observed regional metabolic value is consistent with the observed value of another region. A regression equation was generated from a set of normal metabolic values, and then this equation was applied to patients with symptomatic Huntington's disease and patients at risk for this disorder. The results of the regression method were consistent with observations of the absolute rate for the normal subjects and Huntington's patients. For the at-risk patients, 6 of 18 were found to have reduced caudate metabolism relative to observed thalamic values. Since the initial scan, one of these identified at-risk individuals has developed symptomatic Huntington's disease. The method may be appropriate for other disorders where there are potential subgroups (e.g., schizophrenia) within a diagnostic category.

Brain↗
PubMed1986

Handedness concordance and intelligence discrepancies in identical twins.

The purpose of this study was to determine if the discrepancy in measured intelligence between identical twins concordant for handedness differed measureably from the discrepancy between identical twins discordant for handedness. If handed concordant and discordant twins did differ in terms of the between twin discrepancy in measured intelligence, then one could infer that congenital factors had caused dissociation of handedness and measured intelligence within a twin set. This finding would support Nagylaki and Levy's contention that the found discordance rates for handedness in identical twins is a function of "pathogenic" congenital factors disrupting the genetically determined handedness pattern. More generally, this finding would also support Satz's model with respect to pathological shifts in handedness due to brain insult either in utero or perinatally. However, in the current study, eight sets of identical twins were examined and no evidence was found to support these hypotheses. Instead, in one set where there was a marked discrepancy in measured intelligence, handedness could not be determined precisely for the twin with the lower intelligence quotient.

Journal Article↗
PubMed1985

Plasma membrane associated actin in liver of normal and tumour-bearing rats.

A study was made of the association of actin with different plasma membrane fractions from liver of normal rats and from the enlarged liver of rats bearing a Walker 256 carcinoma where a decrease in the state of polymerisation of cytoplasmic actin has been previously observed. As estimated by the DNAase I inhibition assay, actin constituted approx. 7% and 3%, respectively, of the protein of membrane fractions enriched in lateral or bile-canalicular domains, but only trace amounts were found in the sinusoidal fraction. [3H]Cytochalasin B binding indicated the presence of 20 and 13 pmol of high-affinity binding sites per mg protein in lateral and bile-canalicular fractions, but none in the sinusoidal. Kd for cytochalasin B binding was of the order of 1 nM for lateral and bile-canalicular fractions. Polypeptide profiles obtained by SDS/urea/polyacrylamide gel electrophoresis of non-ionic detergent-insoluble residues differed for all three fractions although some proteins, including actin, occurred as major components of both bile-canalicular and lateral regions. Tumour growth had no effect on the actin content, high-affinity cytochalasin B binding or polypeptide profiles of the three membrane fractions.

Actins↗
PubMed1985

The statistical interaction of cerebral specialization and integration in the interpretation of dynamic brain images.

Two constructs of brain function, namely cerebral specialization and integration, have been examined in the analysis of blood flow and metabolic function resulting from dynamic imaging procedures. The purpose of the current paper is to illustrate the interaction of these two constructs at the statistical level. Because of the statistical interaction, it is argued that the currently accepted statistical evidence for cerebral specialization is, in fact, partially a function of the degree of regional cerebral integration. Therefore, found asymmetries of flow or rate may be solely a function of cerebral integration. These points are discussed with respect to developing a better understanding of stimulus/brain/behavior relations.

Blood Glucose↗
PubMed1984

Correlational methods for determining regional coupling of cerebral glucose metabolism: a pilot study.

The current study presents an alternate method of analyzing PET data by means of a correlational approach. Correlational or coupling patterns of regional cerebral glucose metabolism were found for normal subjects and patients with schizophrenia under electric shock stimulation. At two levels (91 mm and 78 mm) significant differences were found between the coupling patterns of normal subjects and patients with schizophrenia. For the normals, the obtained correlational maps were consistent with the sensory input. However, such patterns were not found for the patients with schizophrenia. Therefore it is suggested that the outlined analysis procedure may complement the standard approach of comparing the mean metabolic rates.

Adolescent↗
PubMed1983

Inhaled foreign bodies in children.

We review a series of 115 children who attended the Royal Children's Hospital in Melbourne between 1979 and 1982 with the diagnosis of inhalation of a foreign body, or in whom a foreign body was found at bronchoscopy. Children between the ages of one and three years were the most commonly affected (75%) and boys outnumbered girls in the ratio 3:2. In 16% of cases the child did not present until more than one week after inhaling the foreign body. A peanut was the most common foreign body found (52% of cases), and it seems that many parents are still unaware that peanut ingestion can be hazardous in very young children.

Anesthesia↗
PubMed1983

Psychometric properties of dichotic words tests.

The current study examined the reliability of a measure of ear advantage and the total scores derived from the dichotic listening task. The scores for both measures were found: (1) not to differ from the normal distribution, and (2) to be reliable over items, tests, and time. However, the total scores were dependent upon stimulus materials and experience. In addition, a psychometric classification model was proposed and it was found that the majority, at least 51.6% of the subjects, did not exhibit a truly measureable ear advantage. Finally, it was argued that total scores as well as ear advantage should be considered in the analysis of dichotic listening studies.

Adult↗
PubMed1983

Effect of tumour growth on hepatic neutral ribonuclease and its inhibitor and on RNA polymerase activity of liver nuclei.

In rats bearing a subcutaneously implanted Walker 256 carcinoma an early rise in liver DNA content was followed by a two-fold increase in RNA content between the 6th and 10th day of tumour growth. Total hepatic neutral ribonuclease and its inhibitor were unaffected by tumour growth. No alteration in RNA polymerase I and II activities of liver nuclei was observed except for a 47% increase in RNA polymerase I on the 8th day of tumour growth.

Animals↗
PubMed1982

Alterations in hepatic 5'-nucleotidase in the tumor-bearing rat.

The effect of the growth of the Walker 256 carcinoma on the level of 5'-nucleotidase and alkaline phosphatase in the whole liver and in an isolated hepatocyte membrane preparation of its host was investigated. Alkaline phosphatase activities of whole liver and plasma membrane were increased approximately 5-fold by tumor growth. A 50% decrease in whole liver 5'-nucleotidase activity was observed in tumor-bearing rats while the 5'-nucleotidase activity per milligram membrane protein was unaltered. Tumor growth would therefore appear to affect a pool of 5'-nucleotidase which is not associated with the plasma membrane.

Alkaline Phosphatase↗
PubMed1982

Age-related changes in insulin receptor regulation in liver membranes from Zucker fatty rats.

Hyperinsulinemic obese rodents have been shown to have reduced insulin binding to liver plasma membranes, a finding consistent with the model of down-regulation of insulin receptors by hyperinsulinemia. In contrast, hepatocytes from the hyperinsulinemic Zucker fatty rat were reported to have insulin binding equivalent to that of lean littermates. We have isolated liver plasma membranes from Zucker fatty rats 10 weeks, 5 months, and 1 yr of age and from fatty rats diet restricted until 5 months and 1 yr of age. We found no evidence for down-regulation of hepatic insulin receptors at 10 weeks of age. However, at 5 months and 1 yr of age there was marked down-regulation evident in isolated liver plasma membranes. Scatchard plots of the data are consistent with a decreased number of receptors rather than changes in receptor affinity accounting for the decreased binding. Diet restriction of the fatty rats resulted in lower plasma insulin levels and less marked down-regulation of hepatic insulin receptors. Our results are consistent with the hypothesis that in developing obesity there is a pattern of developing insulin resistance, first seen in muscle, later in fat, and finally in liver. Regulation of insulin receptors by hyperinsulinemia is probably less important than prior alterations in tissue metabolism by hyperinsulinemia in accounting for insulin resistance.

Aging↗
PubMed1982

Studies on the regulation of insulin binding by liver plasma membranes from Zucker fatty rats.

The hyperinsulinemia of obese rodents has been associated with a reduced number of hepatic insulin receptors except in hepatocytes from fatty Zucker rats. We isolated liver plasma membranes from 10-11-wk-old lean and fatty Zucker rats, some of which were injected with streptozotocin 2--4 wk earlier. We have determined that although the number of hepatic insulin receptors is not reduced in young hyperinsulinemic fatty Zucker rats, the number of receptors can be increased when the hyperinsulinemia of the fatty rats is reduced by treatment with streptozotocin. In the fatty rats, this reduction in circulating insulin is accompanied by a reduction in plasma triglyceride concentration, consistent with a decreased stimulation of hepatic lipogenesis. Competitive binding curves for insulin were obtained with isolated liver plasma membranes and 125I-insulin. Analysis of these curves for affinity and number of receptors indicated that the number of insulin receptors was unchanged for the fatty control rats relative to the lean control rats but was increased in streptozotocin-treated animals. These data indicate that the regulation of hepatic insulin receptors is altered in the young fatty Zucker rat as characterized by a lack of downregulation of hepatic insulin receptors by hyperinsulinemia and an upregulation of hepatic insulin receptors at insulin concentrations higher than those found in lean rats. An altered state of hepatic insulin receptor regulation may be characteristic of developing obesity.

Animals↗
PubMed1981

Actin depolymerising activity in tumour-bearing rats.

The actin depolymerising activity in plasma, liver and gastrocnemius muscle of normal and tumour-bearing rats and in Walker 256 carcinoma grown in the solid and ascitic form was measured. Similar levels of actin depolymerising activity were observed in solid and ascitic forms of the tumour. No alteration in actin depolymerising activity was found to accompany the increased levels of unpolymerised actin found in the plasma and tissues of the tumour-bearing rat. It was concluded that changes in the state of polymerisation of actin in the tissues of the tumour-bearing host could not be attributed to an effect of the tumour on actin depolymerising activity.

Actins↗