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Biomedical subjects

J G Edwards

Publications and source records attributed to J G Edwards.

At least 91 records · Page 5Linked to original sources
PubMed1988

Response of hypertensive rats to acute and chronic conditions of static exercise.

To determine whether chronic static exercise would alter resting caudal artery systolic blood pressure (RSBP) in stroke-prone hypertensive rats (SP-SHR), a 20- to 21-wk experimental study was initiated with 24 male and 16 female rats. In addition, eight rats were cannulated for heart rate and blood pressure measurements and implemented with Doppler flow probes (mesenteric and iliac arteries) for determination of the acute responses. The rats were trained to perform static exercise by forelimb hanging over an electrical grid (3-5 mA) activated with a high-frequency sound (2.5-10kHz) of 60 dB. Acute forelimb hanging by nontrained rats caused a 70-mmHg elevation in mean blood pressure, 115-beat/min increase in heart rate, and 71% decrease in mesenteric blood flow. The procedure for chronic forelimb hanging included increasing the number of sets per session from one to three, maintaining the number of repetitions between 6 and 10 and the hang time within 7-10 s/hang, while increasing the amount of weight supported per set from 0 to 12% of body weights for males and 30% for females. Two performance tests, one for endurance (no weights) and one for "strength" (weights), demonstrated that the hanging animals increased their endurance ability by 103% and their strength by 115%. RSBP was not significantly increased in either the male or female trained populations when evaluated by analysis of variance or trend-analysis procedures. Food and water consumption, sodium and potassium excretion, and blood volume measurements exhibited no group differences that had statistical significance. Five animals had evidence for previous strokes, with four being associated with the nonhanging animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Physical assaults in a psychiatric unit of a general hospital.

The authors collected data concerning assaults, assaultive patients, and victims in a psychiatric unit during a 12-month period and compared them with data from a control group of patients. Thirty-seven assaults by 25 patients were recorded. Fourteen of the victims were patients and 23 were members of staff. The assaultive group contained a significantly higher proportion of schizophrenic patients than did the control group and significantly larger numbers of patients from lower socioeconomic classes, patients admitted involuntarily under a section of the Mental Health Act, and patients with a history of assaults.

Adult↗
PubMed1988

Induction of fibroblast spreading by Mn2+: a possible role for unusual binding sites for divalent cations in receptors for proteins containing Arg-Gly-Asp.

Mn2+ at low (microM) concentrations fulfils the divalent cation requirement for spreading of BHK21 cells on fibronectin. At much higher concentrations, Mn2+ (and to a small extent also Mg2+) induces spreading on haemoglobin, not normally an adhesive protein. Since high Mn2+ also induces spreading of BHK variants unresponsive to exogenous fibronectin, it is unlikely to be acting as a cofactor for secreted cellular fibronectin or by stimulating its secretion. High Ca2+, but not Mg2+, inhibits the induction of spreading by Mn2+ on haemoglobin. Pre-treatment of cells with high concentrations of trypsin decreases the rate of spreading induced by Mg2+ on fibronectin, and by Mn2+ on haemoglobin, to similar extents. High and low Mn2+ could induce spreading, either by different mechanisms or through a common pathway. In the second case, at both concentrations, Mn2+ could act by binding to Ca2+/Mg2+ sites in one or more receptors for adhesion proteins. This would require binding of Mn2+ or Mg2+ to these sites to activate the receptors in the absence of adhesion proteins, and the effect of such proteins to be to increase the affinity of the sites for metal ions. The sites in question may be formed by sequences homologous to those found in the extracellular domains of the vitronectin receptor and platelet membrane glycoprotein IIb. Although very similar to the Ca2+-binding loop in the EF hand of calmodulin, these sequences more closely resemble bacterial galactose-binding protein in lacking one of the conserved co-ordinating side-chains.

Animals↗
PubMed1988

A longitudinal assessment of renal function during treatment with lithium.

Renal function was studied during lithium treatment in 28 patients on two occasions separated by a mean interval of 4.7 years. Glomerular filtration rate, assessed by creatinine clearance and serum creatinine concentrations, showed no impairment. Albumin excretion rate, a marker of glomerular permeability, showed no consistent change. In contrast, a decline in urine concentrating ability (mean 140 mOsm/kg) was found in all patients, exceeding the reduction to be expected from ageing in all but three. These results support the view that treatment with lithium long-term does not damage renal glomerular function, but that progressive impairment of the distal tubular responsiveness to arginine vasopressin is common.

Adult↗
PubMed1987

An unusual case of nicotine dependence.

The case of a 49-year-old woman who has been brushing her teeth for 12 years with large amounts of snuff is described. She was dependent on the habit and had plasma nicotine and cotinine levels similar to those found in heavy smokers. Historical and cultural aspects of the use of snuff are discussed.

Cotinine↗
PubMed1987

Influence of exercise training on resting blood pressures of Dahl rats.

To determine whether female Dahl salt-sensitive (SS) hypertensive rats would adapt to chronic treadmill exercise by exhibiting lower resting systolic blood pressures (RSBP), a 12-wk training program was undertaken. Female Dahl salt-resistant (SR) rats were also trained for the same time period a a similar intensity [40-70% maximal O2 consumption (VO2max)] and duration (55 min). Postexperimental treadmill run times and VO2max values [SR: nontrained (NT) 87 +/- 1, trained (T) 97 +/- 2; SS: NT 82 +/- 2, T 92 +/- 3 ml.min-1 X min-1 X kg-1] indicated that the prescribed program had produced a trained state. However, the training program caused no group differences between the SR or the SS and their nontrained controls in measurements associated with sodium chloride intake, fluid consumption, urine production, 24-h sodium excretion, plasma volumes, plasma insulin, or blood volumes. Chronic exercise did significantly lower RSBP in the SR subgroup after 6 wk (NT 123 +/- 4, T 110 +/- 3 mmHg) and 8 wk (NT 120 +/- 4, T 106 +/- 2 mmHg) and remained lower throughout the remaining weeks of the experiment. On the other hand, the RSBP results of the trained SS rats were significantly higher than the nontrained SS rats after 6 wk (NT 155 +/- 8, T 191 +/- 7 mmHg) and were never significantly different than the controls for the remainder of the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Nomifensine and convulsive seizures.

Four cases of convulsive seizures occurring during treatment with nomifensine have been notified to the Committee on the Safety of Medicines of the United Kingdom, and 22 cases have been reported from other countries. The occurrence of convulsions is not in keeping with the results of animal experiments, studies of epileptic patients treated with nomifensine or observations made following overdoses of this drug. Nomifensine may thus not be entirely free from epileptogenic properties as previously presumed.

Aged↗
PubMed1987

A ten-year follow-up study of Southampton opiate addicts.

A ten-year follow-up study of 74 opiate (most heroin) addicts referred to the Drug Dependence Clinic in Southampton showed that overall, little use was made of the treatment facilities available. Half of the patients on whom we were able to obtain follow-up data appeared to be no longer abusing drugs. An appreciable number of subjects had committed offences prior to abusing drugs and a large proportion offended during the follow-up period, adding support to the view that most addicts are not driven to crime because they are unable to obtain the help they need. The death rate of 15% is that expected in a long-term follow-up study. The results suggest that the natural history of many heroin addicts is uninfluenced by therapeutic intervention.

Adolescent↗
PubMed1987

A major difference between serum and fibronectin in the divalent cation requirement for adhesion and spreading of BHK21 cells.

Adhesion and spreading of BHK21 cells on adsorbed bovine and foetal bovine serum require addition to the medium of a divalent cation. Divalent cations are effective in the order Mn2+ greater than Co2+ greater than Mg2+ greater than Ca2+, with Ca2+ ineffective below 10(-4)M. On purified fibronectin, however, no added divalent cation is required, since the requirement is largely met by adventitious Ca2+ (circa 10(-5)M) in nominally divalent cation-free saline. In such background Ca2+, adhesion and spreading on fibronectin are only slightly slower than in optimal Mg2+, and appear identical, morphologically, and in sensitivity to cytochalasin D. Cells also spread on fibronectin in response to Mg2+, when Ca2+ is buffered below 10(-6)M, showing that external Ca2+ is not needed as a source for an increase in internal Ca2+. Cells can be induced to spread on serum in low Ca2+ by substantially increasing the fibronectin concentration; this supports other evidence that at its unsupplemented concentration, fibronectin contributes little to the spreading of these cells on serum. The Ca2+ requirement for spreading on preparations of vitronectin (serum spreading factor), partially purified from bovine serum, is similar to that on whole serum. Thus the difference in divalent cation requirement between serum and fibronectin may arise because, on serum, the dominant protein responsible for induction of spreading is vitronectin rather than fibronectin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Select cardiovascular and metabolic responses of diabetic rats to moderate exercise training.

The combined influence of diabetes and moderate treadmill exercise training on select metabolic and cardiovascular parameters was investigated with mature male Sprague-Dawley rats assigned to either control diabetic or diabetic groups receiving exogenous insulin. Experimental diabetes was induced with streptozotocin (80 mg.kg-1, i.v.) and verified by blood glucose concentrations greater than 16 mmol. The animals were designated as control, insulin-injected (5 U.kg-1, twice daily), or saline-injected (twice daily), and assigned to either non-trained or trained sub-groups. Insulin treatment partially restored the measured physiological functions to within normal limits. All animals were trained at 60 to 70% maximal oxygen consumption for 9 wk and exhibited higher maximal oxygen consumption values and cytochrome oxidase activity of the soleus muscles. Diabetes caused lower (P less than 0.05) reductions in resting heart rate but training-induced bradycardia did not occur in any group. Heart rate response to atropine sulfate (1 mg.kg-1, atrial choline acetyltransferase activity, atrial acetylcholine concentration, and quinuclidinyl benzilate binding was measured to evaluate changes in the parasympathetic nervous system. Atropine-induced cardiac acceleration was most pronounced in control and least effective in diabetic animals. Endurance training had no meaningful influence on this response to cholinergic inhibition. Quinuclidinyl benzilate binding for the diabetic and the diabetic groups receiving insulin revealed no change in receptor number, receptor affinity, or training effects. These findings indicated that 9 wk of exercise training improves the aerobic capability of insulin-deficient rats without changing cardiovascular characteristics associated with the parasympathetic nervous system.

Acetylcholine↗
PubMed1986

A case of resistant schizophrenia.

In an era when it is generally believed that the acute symptoms of schizophrenia can be controlled pharmacologically, the case of a young man who has remained almost continuously floridly psychotic for 13 years, despite treatment, is disquieting. Conventional psychiatric treatment appears to be rendered impotent. It is in this context that it may be of interest to report a summary of the proceedings of a Special Problems Conference held at the Institute of Psychiatry on 18 February 1985 to discuss such a case.

Adult↗
PubMed1985

Variants of polyoma-transformed BHK21 cells unresponsive to fibronectin.

To investigate the relation between cell-substratum adhesion and cell-spreading we have isolated variants of anchorage-independent cells which fail to adhere to fibronectin. The variants are poorly adhesive both to fibronectin and serum, show dramatically altered morphology in culture and are unable to spread on any protein-coated surface yet tested.

Animals↗
PubMed1985

Influence of exercise training on reactivity and contractility of arterial strips from hypertensive rats.

To determine whether the lowered resting blood pressure values in hypertensive rats were associated with changes in vascular reactivity and/or contractility, helical strips were obtained from different arteries from exercise-trained (running and swimming) hypertensive rats and from running normotensive rats. Each subgroup contained nontrained controls for comparison. Changes in muscle aerobic enzymes, maximum O2 consumption, and body weight indicated that a training effect had occurred. When norepinephrine was added in a dose-response manner to the testing chamber containing helical strips from either the descending aorta, femoral artery, or renal artery, there were no significant differences in reactivity (the negative log dose-response curve) attributable to the training of hypertensive or normotensive groups. However, the trained hypertensive rats exhibited a trend for lower contractility values (dyn/mm2) in some but not all of the strips tested. From these results, we concluded that the lowered resting blood pressures associated with exercise training of hypertensive rats could not be explained by changes in vascular reactivity of their arterial strips.

Animals↗
PubMed1985

Neuroleptics, lithium and renal function.

Renal function test results in 26 patients on neuroleptic treatment, who had never received lithium or antidepressants, were compared with those in a matched group, treated with lithium; also, their tubular response to DDAVP was compared with that of 25 control subjects. Measurements of serum creatinine, creatinine clearance, and urinary albumin excretion showed no abnormality attributable to either neuroleptics or lithium. The maximum urine concentrating ability after DDAVP was significantly lower in the neuroleptic group than in controls, but significantly higher than in the lithium-treated patients. There was a significant correlation between excretion of urinary beta 2-microglobulin and duration of neuroleptic treatment, but mean excretion rates were the same in both treatment groups. The results suggest that neuroleptics as well as lithium impair urine concentrating ability.

Acetylglucosaminidase↗
PubMed1985

Efficacy of topical chloramphenicol and tobramycin ophthalmic solutions in preventing severe Staphylococcus aureus keratitis in rabbits.

Various marketed chloramphenicol ophthalmic solutions were compared and various dilutions of Tobrex Ophthalmic Solution were tested for effectiveness in a Staphylococcus aureus rabbit keratitis model. Anesthetized rabbits were each infected intracorneally with 10(4) Staphylococcus aureus ATCC 29737 cells. Treatment groups consisted of five or six rabbits (10 or 12 eyes) per group. One group of rabbits was infected but not treated (Positive Control Group). Topical dosing of commercially available ophthalmic solutions was accomplished by depositing 0.1 mL of a color-coded test solution into the lower cul-de-sac of each eye. Dosing begin one hour after the mid-infection time and continued for a total of nine hourly treatments. Twenty-four hours after infection the rabbit eyes were graded (masked) using standard slit-lamp scoring procedures. The slit-lamp scores for five of eight ocular parameters were used to calculate an eye score value for each rabbit eye. The five ocular parameters were selected, based on previous Stepwise Discriminant Computer Analysis of over 300 rabbit eyes infected with Staphylococcus aureus ATCC 29737 and treated with various antibiotics. The eye score values for each group were averaged and the treatments were compared for significant differences in efficacy using the nonparametric, Wilcoxon-Mann-Whitney Rank Sum Test.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Investigating renal function during lithium treatment.

The tests that have been used to assess glomerular and tubular function in patients receiving treatment with lithium have been reviewed. The advantages and disadvantages of these are discussed. The most useful tests are the creatinine clearance, which may be predicted from the serum creatinine using a formula or nomogram, and the measurement of urine osmolality, followed if necessary by assessment of the maximum urine concentrating ability after desamino cys-1-8-D arginine vasopressin.

Acetylglucosaminidase↗