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Biomedical subjects

A J Yates

Publications and source records attributed to A J Yates.

At least 163 records · Page 9Linked to original sources
PubMed1985

The effects of cognitive task demand on subjective stress and blood glucose levels in diabetics and non-diabetics.

Blood glucose levels (BGLs) and subjective estimate of stress levels (SESLs) were measured repeatedly in 45 min baseline sessions on three successive days in insulin-dependent diabetic and non-diabetic groups. In the diabetic groups the initial level of BG was twice that of the non-diabetic group and BGLs declined steadily within each session but not across sessions whereas BGLs in the non-diabetic group remained steady both within and across sessions. On two subsequent days half of each group performed a high demand and half a low demand task, BGLs and SESLs being assessed before, during and after the stress period. Stress did not appear to induce significant changes in BGL in any of the groups even though SESL measures indicated that the task appeared stressful to the groups. The implications of these findings for the relationship between stress and increases or decreases in BGL are discussed.

Adult↗
PubMed1985

Self-efficacy as a predictor of relapse following voluntary cessation of smoking.

In a retrospective study 92 subjects who had quit smoking voluntarily one year earlier were classified on the basis of self-report as abstainers or relapsers. Discriminant function analysis of 11 variables showed that a 14-item self-efficacy questionnaire total score was as successful in classifying the subjects as abstainers or relapsers as analyses involving all 11 variables or the best combination of them. In a prospective study 32 subjects were administered the same variables shortly after quitting smoking and before eventual status was known. Using weights derived from the retrospective study the self-efficacy total score predicted the status of all 15 subjects who had relapsed at a four month follow-up while the seven subjects it had predicted would not relapse were still abstaining. At an eight month follow-up the predictive power of the self-efficacy measure was maintained. At both follow-up points the self-efficacy measure proved superior to the other measures. These results suggest that the self-efficacy measure may be used to identify individuals at high risk for relapse after voluntarily quitting smoking; and may enable remedial measures to be applied prior to the decision to quit being taken which would reduce the probability of relapse.

Adult↗
PubMed1985

Treatment of malignant hypercalcaemia with clodronate.

We have assessed the effects of clodronate (dichloromethylene diphosphonate; Cl2MDP 0.8-3.2g daily by mouth for up to 3 months) in 17 episodes of hypercalcaemia and osteolysis due to carcinoma. Clodronate reduced serum calcium in 14 episodes and bone resorption in all patients. These remained suppressed for the duration of treatment, but recurred promptly when treatment was stopped. Clodronate may be a useful measure for controlling hypercalcaemia and osteolysis in patients with carcinoma.

Adult↗
PubMed1985

Application of flow cytometry to analyses of cultured human glioma and fetal brain cells.

Methods are described to study cell surface and cytoplasmic antigens of cultured human glioma, fetal brain cells and fibroblasts using flow cytometry. This required harvesting the cultured cells with Versene or mild trypsin treatment and fixation in 4% paraformaldehyde prior to staining for glial fibrillary acidic protein (GFAP) and fibronectin using indirect immunofluorescence. At passage 10, 38% of fetal brain cells [CHII] were GFAP-positive but at passage 14 only 3.5% expressed GFAP. Two glioblastomas and an anaplastic astrocytoma had 38.8%, 6.7% and 81.3% GFAP-positive cells, respectively. Of the 10(4) cells studied, 91.6%, 79.1% and 40.8% were fibronectin-positive for glioblastoma multiforme [12-18], oligodendroglioma [12-10] and fetal brain [CHII] cells, respectively. Two fibroblast lines had 33.5% and 43.1% of the cells expressing fibronectin. The validity of these results was confirmed by staining for GFAP and fibronectin using peroxidase-antiperoxidase and immunofluorescence microscopy. Using low angle forward light scatter to estimate cell size and gating techniques it was found that GFAP-positive CHII and anaplastic astrocytoma cells were generally larger than GFAP-negative cells of the same type. No correlation between cell size and fibronectin expression was found for glioblastoma [12-18] cells. These results demonstrate the validity of the described methods and illustrate some specific applications and the potential value of flow cytometry to neurooncology.

Brain Neoplasms↗
PubMed1985

Resistance to natural killer cytolysis and neutral glycolipid composition of cultured human glioma and fetal brain cells.

Natural killer cells (NK) demonstrate cytotoxicity against a wide range of cultured cells without prior sensitization, and the sensitivity of many target cells to NK attack is altered by exposure to interferon. The structures on the target cells conferring sensitivity or resistance to NK are not known, but glycolipids are suggested to be related to NK susceptibility. To determine possible relationships between target cell glycolipids and NK cytolysis, the effects of human beta-interferon (IFN) on the neutral glycolipid composition and sensitivity to NK cytolysis of cultured cells from four human gliomas and two fetal brains were analyzed. Compared to MOLT-4 and Raji cells all six neural cell lines were quite resistant to NK, and IFN slightly increased this resistance. IFN also caused increases in the amounts of non-hydroxy fatty acid cerebroside, ceramide trihexoside, asialo-GM1, asialo-GM2 and globoside. Increased molar proportions of ceramide tri- and tetra-saccharides occurred in the two glioma lines which had the greatest increases in NK resistance following IFN exposure. It is concluded that neutral glycolipids may play a role in the mechanisms responsible for resistance of some glioma cells to NK cytolysis.

Astrocytoma↗
PubMed1985

Biochemical markers and skeletal metabolism in carcinoma of the prostate. Use of decision matrix theory and ROC analysis.

The discriminative ability of several skeletal and tumour markers was assessed in 102 patients with prostatic disease. These comprised serum acid and alkaline phosphatase, serum albumin and osteocalcin, urinary excretion of calcium, hydroxyproline and 6-oxo prostaglandin F1 alpha. None of the tests was of value in distinguishing patients with benign prostatic disease from those with tumour not involving the skeleton. Values of serum osteocalcin, urinary excretion of calcium and urinary 6-oxo prostaglandin F1 alpha failed to discriminate significantly between patients with or without metastases. The remaining four markers were compared by decision matrix analysis and receiver operating characteristic (ROC) curves. Serum alkaline phosphatase provided the most sensitive marker of skeletal metastases (80.5%), followed by serum acid phosphatase (80%), hydroxyproline (68%) and albumin (30%). ROC analysis suggested that alkaline phosphatase conformed most closely to the "ideal marker" with highest specificity and sensitivity.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Effects of interferon and gangliosides on growth of cultured human glioma and fetal brain cells.

Human beta-interferon (IFN) induced an antiviral state in two fetal brain and six glioma cell lines. The growth-inhibitory effect of IFN was most pronounced on three glioblastoma lines and least on fetal brain and oligodendroglioma cells; IFN growth inhibition of one schwannoma and one anaplastic cell line was intermediate between the two other groups. Thus, the growth-inhibitory effect of IFN generally correlated with the degree of anaplasia of the tissue from which the cells were derived. IFN (1000 units/ml) had to be present for 24 to 48 hr to have a significant inhibitory effect on growth of glioblastoma (12-18) cells. However, growth inhibition of 12-18 cells exposed to IFN for 3 days persisted for 3 weeks. Both sialic acid-N-acetylgalactosamine ganglioside and a mixture of normal human brain gangliosides (50 microM) inhibited growth of fetal brain (CHII) but not glioblastoma 12-18 cells. However, preincubation of cells with either sialic acid-N-acetylgalactosamine or a mixture of gangliosides did not augment the growth-inhibitory effects of IFN on either CHII or 12-18. These results indicate that gangliosides and IFN may be operating through different mechanisms to cause growth inhibition.

Brain↗
PubMed1985

Creutzfeldt-Jakob disease presenting as progressive aphasia.

The syndrome of slowly progressive aphasia usually has been associated with Pick's disease, Alzheimer's disease, or an isolated focal degenerative disorder of unknown etiology involving the left perisylvian cortex. This report is of a patient with progressive aphasia due to Creutzfeldt-Jakob disease.

Aphasia↗
PubMed1984

Biosynthesis and transport of gangliosides in peripheral nerve.

Radiolabelled glucosamine was injected into L-7 dorsal root ganglion (DRG) of rabbits. At several different times after injection DRG, lumbosacral trunks (LST) and sciatic nerves (SN) removed and gangliosides extracted. Two and 3 weeks after injection the amounts of radioactivity in the ganglioside fractions of LST SN were significantly higher than at days 1 and 2. The TCA soluble radioactivity decreased dramatically over the same time period. Colchicine prevented the appearance of radiolabelled lipid in LST and SN. From these experiments we conclude that some ganglioside is synthesized in the neuronal cell bodies of DRG and transported in the axons of the sciatic nerve. In another experiment the sciatic nerve was transected and ends separated to prevent regeneration. Ganglioside synthesis and transport were studied in these animals the same way as the previous experiment. There was no difference the amount of radiolabelled ganglioside that was isolated from DRG or LST of transected compared with control nerves. The behavior of several potential acid soluble contaminants was studied in several steps used to isolate gangliosides. Of those studied only CMP-NeuAc could cause significant contamination of the final ganglioside preparation.

Animals↗
PubMed1984

Individual differences in the ability to discriminate the direction of spontaneous changes in peripheral finger temperature.

Spontaneous fluctuations of .1 degrees C in peripheral finger temperature were recorded for a 30-minute baseline period in 10 subjects. Those meeting specified criteria of temperature fluctuations were then asked to judge the direction of change in computer-detected temperature fluctuations of .1 degrees C, first without feedback, then with feedback (knowledge of results). Only 1 subject produced convincing evidence of ability to make directional judgments at better than chance level, though more training with feedback might have benefited other subjects. The theoretical significance of these results for the relationship between discrimination and voluntary control is discussed.

Adolescent↗
PubMed1984

Behavior of sugar derivatives in procedures for ganglioside isolation.

A common method of studying ganglioside metabolism is to measure the amounts of radioactivity incorporated into ganglioside from a radiolabeled precursor. This requires that radioactive nonganglioside material be completely removed from the ganglioside fraction. Nucleotide sugars and aminosugars comprise an important source of such contaminants. Therefore, we have studied their behaviors in several procedures currently employed to isolate gangliosides. Over 50% of the radioactivity associated with several nucleotide sugars added to a brain homogenate is extracted with chloroform/methanol (2:1, v/v), and most of this is recovered in the upper phase of a Folch partition. Dialysis against water removes almost all of the free aminosugar but only 70% of nucleotide sugar. Treatment with alkaline phosphatase, phosphodiesterase and alkaline methanol followed by dialysis removes almost all of the nucleotide diphosphate sugars but only 88% of cytidine 5'-monophosphate sialic acid (CMP-NeuAc). Nucleotide sugars cannot be separated from gangliosides by Unisil or Iatrobead chromatography, but nucleotide diphosphate sugars and gangliosides are resolved with Sephadex LH-20 chromatography following treatment with phosphodiesterase and alkaline phosphatase. CMP-NeuAc was not satisfactorily separated from gangliosides using any of the procedures.

Brain Chemistry↗
PubMed1984

Serum lipids and lipoprotein composition in spontaneously diabetic BB Wistar rats.

Serum lipid and lipoprotein composition in spontaneously diabetic BB Wistar rats, nondiabetic littermates, and control Wistar rats was studied to elucidate diabetes-related abnormalities of lipoprotein composition. Serum total triglycerides and pre-beta-lipoprotein concentrations of insulin-treated spontaneously diabetic BB and nondiabetic littermate rats were significantly higher than those of control Wistar rats. Serum cholesterol and HDL cholesterol concentrations of spontaneously diabetic BB and nondiabetic littermate rats did not differ from controls. Concentrations of very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) of spontaneously diabetic BB and nondiabetic littermate rats were higher than those of normal rats. With sodium dodecylsulfate-polyacrylamide gel electrophoresis it was observed that the spontaneously diabetic BB and nondiabetic littermate rat VLDL contained higher percentages of apoE relative to total apoC when compared with control Wistar rats. With isoelectric focusing, apoC-II relative percentages in VLDL and HDL of both spontaneously diabetic BB and nondiabetic littermate rats were higher than apoC-II proportions in VLDL and HDL of controls. Apolipoprotein A-I of the control rat HDL showed four isoforms that focused at pI 5.8 (17.3%), 5.75 (30.6%), 5.65 (31.8%), and 5.55 (20.5%); however, the spontaneously diabetic BB and nondiabetic littermate rat HDL apoA-I was mainly represented by two isoforms that focused at pI 5.8 and 5.75. VLDL of both diabetic and nondiabetic BB rats contained higher levels of acidic apoE isoforms compared to their counterparts in control Wistar rats. Although HDL cholesterol concentrations of spontaneously diabetic BB rats remained normal, protein concentrations were higher resulting in a low cholesterol/protein ratio in HDL suggesting that the cholesterol-carrying capacity of spontaneously diabetic BB rat HDL could be less than normal and may be due to an abnormal apoA-I composition. Quantitative alterations of lipid and lipoprotein composition appear in the BB Wistar rat when compared to the Wistar rat, but some of the changes are more pronounced in the spontaneously diabetic BB Wistar rat.

Animals↗