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Biomedical subjects

J Bond

Publications and source records attributed to J Bond.

At least 19 recordsLinked to original sources
PubMed1992

Effect of serum growth factors and phorbol ester on growth and survival of human thyroid epithelial cells expressing mutant ras.

We previously demonstrated a high incidence of ras mutation in thyroid follicular (epithelial) cell neoplasms and showed that expression of mutant ras is a potent mitogenic stimulus for normal human follicular cells in culture. Here we show that induction of cell proliferation in primary follicular cells by a mutant human Ha-ras (val 12) expressed from a retroviral vector was absolutely dependent on the presence of serum growth factors. Induction of DNA synthesis showed partial dependence. Mutant ras-induced growth was also inhibited by exposure to phorbol ester at concentrations sufficient to downregulate protein kinase C. More importantly, we observed an unexpected toxic effect of phorbol ester in this system that was specific to cells expressing mutant ras. This has potential significance both for elucidating the basic mechanism of ras action in epithelial cells and also as a pointer to a novel therapeutic strategy.

Animals↗
PubMed1992

Development of a measure of professional collaboration in primary health care.

STUDY OBJECTIVE: The aim was to develop indices of the degree of collaboration between district nurses, general practitioners, and health visitors. DESIGN: Semistructured interviews were conducted with each member of a pair of professionals who had patients in common. In each district a stratified random sample of six general practitioners and six community nurses was drawn, and for each a "partner" of the other profession was sampled. SETTING: A stratified random sample of 20 district health authorities in England. PARTICIPANTS: Complete interviews were obtained with 148 doctor-nurse and 161 doctor-health visitor pairs. MAIN RESULTS: Only 27% of general practitioners and district nurses with patients in common and 11% of general practitioners and health visitors collaborate. Stepwise logistic discriminant analysis was used to develop measures of collaboration between general practitioners and district nurses and between general practitioners and health visitors. The indices of collaboration were calculated from the responses of the community nurse to at most 10 questions. CONCLUSIONS: The indices developed here might be used as a measure of one aspect of the quality of service offered by a primary health care team or to assess the effect of changes in working patterns or the degree of collaboration within the organisation.

Community Health Nursing↗
PubMed1992

The inhibitory effects of cromakalim and its active enantiomer BRL 38227 against various agonists in guinea pig and human airways: comparison with pinacidil and verapamil.

The effects of the potassium channel activators, cromakalim, BRL 38227 and pinacidil, and the calcium antagonist, verapamil, have been compared against various spasmogens on airway responses in vitro and in vivo in the guinea pig and also in human isolated bronchi. In guinea pig tracheal spirals, potassium channel activators generally had a greater inhibitory effect than verapamil against tone induced by a wide range of spasmogens (spontaneous, 5-hydroxytryptamine, leukotriene D4, prostaglandin E2). The potassium channel activators had very little effect against potassium chloride- and carbachol-induced tone in guinea pig tracheal spirals [e.g., cromakalim (20 microM) induced relaxations of 0.21 +/- 0.03 (relative to an isoprenaline maximum = 1.0, mean +/- S.E.M.) against carbachol, compared to 0.77 +/- 0.03 against histamine]. In vivo, the potassium channel activators prevented histamine and 5-hydroxytryptamine-induced bronchoconstrictions, but had little inhibitory effect against acetylcholine. In contrast, in human bronchi, cromakalim was capable of inducing powerful concentration-dependent relaxations against carbachol-induced tone [cromakalim (20 microM) induced relaxations of 0.77 +/- 0.09 (relative to isoprenaline = 1.0, mean +/- S.E.M.) against carbachol, compared to 0.95 +/- 0.04 against histamine]. In human bronchi, all the inhibitory agents were more potent and more effective, except that verapamil did not have an increased maximum response. We conclude that potassium channel activators should be effective at relaxing contractions induced by a wide range of spasmogens in man.

Animals↗
PubMed1991

Physiological glucocorticoid levels regulate glutamine and insulin-mediated glucose metabolism in skeletal muscle of the rat. Studies with RU 486 (mifepristone).

This study examined the effects of antagonism of the peak level of glucocorticoids in vivo, which occurs as rats enter the feeding/activity (dark) period on glucose and glutamine metabolism in incubated isolated rat soleus muscle preparations. Thus the rats were treated with the potent glucocorticoid antagonist RU 486 2 h before and 1 and 2 h into the dark period. Both the content of glutamine in skeletal muscle in vivo and plasma glucose and glutamine concentrations were elevated midway through the dark period, compared with the beginning of the period. RU 486 prevented the increases in plasma glucose and glutamine and caused a significant decrease in both the rate of release of glutamine in soleus muscle in vitro and the content of glutamine in gastrocnemius muscle. The sensitivity of soleus muscle to insulin in vitro is markedly decreased when isolated midway through the dark period (i.e. at 03:00 h) [Leighton, Kowalchuk, Challiss & Newsholme (1988) Am. J. Physiol. 255, E41-E45]. We now show that the concentrations of insulin required to stimulate lactate formation and glycogen synthesis half-maximally were 95 and 250 muunits/ml respectively, and treatment of rats with RU 486 decreased these values to 55 and 90 muunits of insulin/ml respectively. Thus antagonism of the action of the normal circadian rise in the level of glucocorticoids in rats reverses insulin insensitivity in soleus muscles in vitro.

Alanine↗
PubMed1991

The effect of tumour bearing on skeletal muscle glutamine metabolism.

1. The effects of tumour bearing on glutamine metabolism in rat skeletal muscle were examined using the Walker 256 carcinosarcoma. 2. There was a rapid and marked decrease in skeletal muscle glutamine content, which was correlated with the size of the tumour, and a decrease in plasma glutamine concentration. 3. The rate of release of glutamine from EDL muscle in vitro was increased in cachectic, tumour bearing animals, but was unaffected from the soleus muscle of the same animals. 4. It is hypothesized that the increase in the rate of muscle glutamine release during cachexia represents a response of this tissue in order to satisfy the demand for glutamine by the tumour or by cells of the immune system.

Animals↗
PubMed1991

In vitro assembly of gap junctions.

Gap junction structures were assembled in vitro from octyl-beta-D-glucopyranoside-solubilized components of lens fiber cell membranes. Individual pore structures (connexons), short double-membrane structures, and other amorphous material were evident in the solubilized mixture. Following the removal of the detergent by dialysis, these connexons associated to form single- and double-layered, two-dimensional hexagonal arrays (unit cell size a = b = 8.5 nm). The formation of larger arrays was dependent on the lipid-to-protein ratio and the presence of Mg2+ ions. Crystallographic analysis of electron micrographs revealed that lens junctional connexons consisted of six subunits surrounding a stain-filled channel. Upon further detergent treatment, in vitro assembled gap junctions were insoluble and formed three-dimensional stacks while other components were solubilized. SDS-PAGE and mass data from scanning transmission electron microscopy strongly suggest that a 38-kDa polypeptide, which is a processed form of the lens specific gap junction protein MP70, is a major component of the arrays. The in vitro assembly of gap junctions opens new avenues for the structural analysis of gap junctions and for the study of the intermolecular interactions of connexons during junctional assembly.

Animals↗
PubMed1991

Cost of continuing-care facilities in the evaluation of experimental national health service nursing homes.

In this paper the costing method and results from the UK evaluation of National Health Service (NHS) nursing-home and continuing-care hospital accommodation for elderly people are presented. Results demonstrate that, in deciding on the relative efficiency of NHS nursing-home and hospital accommodation, it should be possible to provide NHS nursing-home care at a cost which is no greater than its hospital counterpart. Cost implications of future developments should be monitored in the possible event that they are set up differently from the NHS nursing homes discussed in this paper. Despite being more costly than private-sector nursing-home accommodation, NHS nursing homes cater for a less able group of people, although some overlap exists. The implications of such results are discussed in the light of the UK Government's recent proposals to reform both the NHS and community care.

Costs and Cost Analysis↗
PubMed1991

Evolutionary aspects of superoxide dismutase: the copper/zinc enzyme.

Copper/zinc superoxide dismutase is typically an enzyme of eukaryotes. The presence of the enzyme in the ponyfish symbiont Photobacterium leiognathi and some free living bacteria does not have an immediate explanation. Amino acid sequence alignment of 19 Cu/Zn superoxide dismutases shows 21 invariant residues in key positions related to maintenance of the beta-barrel fold, the active site structure including the electrostatic channel loop, and dimer contacts. Nineteen other residues are invariant in 18 of the 19 sequences. Thirteen of these nearly invariant residues show substitutions in Photobacterium Cu/Zn superoxide dismutase. Copper/zinc superoxide dismutase from the trematode Schistosoma mansoni shows an N-terminal sub-domain with a hydrophobic leader peptide, as in human extracellular superoxide dismutase which is a Cu/Zn enzyme. The latter also has a C-terminal sub-domain with preponderance of hydrophilic and positively charged residues. The amino acid sequence of this superoxide dismutase between the N-terminal and C-terminal regions shares many features of cytosolic Cu/Zn superoxide dismutase, including 20 of the 21 invariant residues found in 19 Cu/Zn enzymes, suggesting a similar type of beta-barrel fold and active site structure for the extracellular enzyme.

Amino Acid Sequence↗
PubMed1991

Mutation of the p53 gene in a differentiated human thyroid carcinoma cell line, but not in primary thyroid tumours.

The p53 gene has been implicated as a tumour suppressor, with mutations occurring in many carcinomas, such as colon, breast and lung. We have sequenced exons 5, 7 and 8 containing conserved gene regions in the only available differentiated thyroid follicular carcinoma cell line and found a mutation at position 273, Arg----His, with no normal allele present. The same mutation was also present in DNA from the tumour of origin. However immunohistochemical analysis of 129 human thyroid tumours using a panel of p53 antibodies was unequivocally negative. Southern blotting in 20 cases failed to demonstrate any deletion or rearrangement, and direct genomic sequencing of 20 carcinomas showed normal DNA sequence for exons 5, 7 and 8. Thus p53 abnormalities may not be important in human thyroid carcinogenesis, in contrast to colon, breast and lung. However, the FTC 133 cell line was only established after 132 unsuccessful attempts with other differentiated thyroid follicular tumours. Since this line and the corresponding tumour of origin have a p53 mutation, we propose that p53 mutation may confer on thyroid follicular tumour cells the ability to grow in culture. This has potential applications for the future development of thyroid carcinoma cell lines.

Antibodies, Monoclonal↗
PubMed1990

Effects of hyperthyroidism and hypothyroidism on glutamine metabolism by skeletal muscle of the rat.

1. The effects of hyperthyroidism and hypothyroidism on the concentrations of glutamine and other amino acids in the muscle and plasma and on the rates of glutamine and alanine release from incubated isolated stripped soleus muscle of the rat were investigated. 2. Hyperthyroidism decreased the concentration of glutamine in soleus muscle but was without effect on that in the gastrocnemius muscle or in the plasma. Hyperthyroidism also increased markedly the rate of release of glutamine from the incubated soleus muscle. 3. Hypothyroidism decreased the concentrations of glutamine in the gastrocnemius muscle and plasma but was without effect on that in soleus muscle. Hypothyroidism also decreased markedly the rate of glutamine release from the incubated soleus muscle. 4. Thyroid status was found to have marked effects on the rate of glutamine release by skeletal muscle per se, and may be important in the control of this process in both physiological and pathological conditions.

Alanine↗
PubMed1990

Effects of physiological and pathological levels of glucocorticoids on skeletal muscle glutamine metabolism in the rat.

The effects of physiological and pathological concentrations of glucocorticoids were investigated using the glucocorticoid antagonist RU486 and the synthetic glucocorticoid dexamethasone, respectively. The effects of these treatments on the concentrations of glutamine and other amino acids in skeletal muscle and plasma and on the rates of release of glutamine and alanine from incubated preparations of skeletal muscle of the rat were investigated. Dexamethasone treatment increased the concentration of glutamine and the rate of release of this amino acid from incubated soleus muscle preparations. This treatment decreased the concentration of glutamine in both gastrocnemius and EDL muscles, but was without effect on the rate of glutamine release from EDL muscles. In contrast, administration of the glucocorticoid antagonist RU486 decreased the rate of glutamine release from muscle. It is concluded that glucocorticoids have marked effects on the metabolism of glutamine by skeletal muscle per se and that these hormones may be important in the control of the rate of glutamine release from muscle in both physiological and pathological conditions.

Amino Acids↗
PubMed1990

Thyroid hormone analogue SKF L-94901: effects on amino acid and carbohydrate metabolism in rat skeletal muscle in vitro.

In summary, hyperthyroidism increased the rate of glycolysis and decreased glycogen synthesis in isolated incubated rat soleus muscle preparations. SKF 901 also increased glycolysis, but the stimulation was 5-fold less than in T3-treated muscles. Hyperthyroidism increased the rate of glutamine release from skeletal muscle, but SKF 901 did not affect glutamine metabolism.

Amino Acids↗
PubMed1990

HIV and measures to control infection in general practice.

OBJECTIVE: To assess the impact of HIV on procedures to control infection in general practices. DESIGN: A postal questionnaire survey. SETTING: General practices throughout Britain. SUBJECTS: 5359 General practitioners, 3429 (63.9%) of whom returned the questionnaire. MAIN OUTCOME MEASURE: Response to questionnaire on knowledge about HIV and policies for controlling infection. RESULTS: Most doctors (2018) had started to wear gloves when taking blood. Almost half (1510) had not resheathed needles previously but a further 776 had adopted this policy because of HIV. Over half of the doctors did not know or were unsure about the risk of infection from needlestick injuries, and 1759 had no practice policy for controlling infection. CONCLUSIONS: Many doctors are uncertain about measures to control infection in general practice. More information and advice are needed to help doctors develop policies to protect patients and staff.

Acquired Immunodeficiency Syndrome↗
PubMed1990

An exploratory study of statistical assessment of papers published in the British Medical Journal.

Statistical assessment of papers submitted to the British Medical Journal has increased to some 300 papers annually. The assessment produces a recommendation to the editor on each paper from a statistical viewpoint together with a completed checklist that indicates the quality of certain important features. This exploratory study was aimed at monitoring the process. It reports a comparison of checklist answers on 45 papers as originally submitted with those on the papers as subsequently published. Of the 45 papers, only 5 (11%) were considered statistically acceptable at submission, but this increased to 38 (84%) after publication. Revisions had not been made adequately in 4 of the 7 unsatisfactory published papers, and the 3 others were thought to be of dubious validity. A major omission from at least 28 papers was information on sample size calculations. It is concluded that statistical assessment is beneficial but that further efforts by authors and assessors could make it even more effective.

Peer Review↗