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Biomedical subjects

A M Davison

Publications and source records attributed to A M Davison.

At least 127 records · Page 7Linked to original sources
PubMed1986

Renin and beta-blockade: prorenin and aldosterone may explain the controversy.

The role of the renin-aldosterone system in predicting the hypotensive effect of beta-blockade is controversial. We have measured blood pressure, heart rate, plasma active renin, prorenin and aldosterone in 44 hypertensive patients before and after 18 weeks treatment with either nadolol or metoprolol in a double blind randomized study. Prorenin increased and active renin decreased with treatment, total renin and aldosterone remaining unchanged. After beta-blockade the correlation between active renin and prorenin improved from p less than 0.025 to p less than 0.001, and both variables attained a correlation with aldosterone. There was a weak correlation between the reduction in diastolic pressure and both pretreatment active renin and pretreatment prorenin (p less than 0.05). However, using a multiple regression analysis there was a highly significant correlation between the combination of the pretreatment values of active renin, prorenin and aldosterone and the reduction in diastolic pressure with both nadolol (p less than 0.001) and metoprolol (p less than 0.003). This indicates that the combination of active renin with prorenin and aldosterone is a reliable guide to the hypotensive effects of beta-blockade and that the failure to detect this in previous studies is most likely due to errors in the measurement of renin.

Adrenergic beta-Antagonists↗
PubMed1986

An ultrastructural morphometric study of membranous glomerulonephritis.

Sixteen cases of membranous glomerulonephritis and 17 controls were studied using electron microscopy and morphometry of whole glomerular cross-sections. It was found that, in relation to controls, in membranous glomerulonephritis the following parameters are increased: total area, total number of cells, all basement membrane parameters, visceral epithelium compartment area and visceral epithelial cell area, area of parietal epithelium, mesangium and urinary space, number of endothelial and mesangial cells; by contrast, the following are decreased: number of visceral epithelial cells, capillary and endothelial volume fractions. Correlation analysis between morphometric and clinical parameters demonstrated significant correlations between capillary basement membrane thickening and duration of disease, proteinuria and renal function; the changes in visceral epithelial cells correlated with serum albumin, proteinuria and inverse of creatinine; changes in relative area of capillary lumina correlated with blood pressure. It is concluded that the ultrastructural morphometric study of renal biopsies will lead to better understanding of glomerular disease.

Basement Membrane↗
PubMed1986

Persistent infection as a cause of renal disease in patients submitted to renal biopsy: a report from the Glomerulonephritis Registry of the United Kingdom MRC.

We report the results of a survey within the United Kingdom of the importance of persistent systemic infection in patients with unexplained renal disease who undergo renal biopsy. Twenty-two units participated. Overall 1.7 per cent of patients undergoing biopsy had an infection but there was large variation between units. Interstitial nephritis and amyloid deposits were more common in patients with infection, and minimal change nephropathy was less common than in patients undergoing biopsy but without infection. The respiratory tract was the most common site of infection but was rarely associated with glomerulonephritis of which the most common cause was infective endocarditis. Drug treatment may have caused the renal lesion in 16 per cent of patients. Amyloid deposits, present in 13.6 per cent of patients, was the most common cause of progressive renal failure. Most other patients had some improvement in renal function once the putative cause, whether infection or antibiotic, was removed.

Adolescent↗
PubMed1985

Uptake and disposal of BSA-coated latex particles by the rat mesangium: reaction with subsequently administered heterologous antiserum.

Mesangial uptake and disposal of antigen-coated latex particles and the ability of subsequently injected antibody to maintain complexed antigen in the rat mesangium has been investigated. Carboxylate-modified latex particles, coated with bovine albumin (BSA) were injected i.v. to 36 Wistar rats. Twenty-two rats (group 1) were not treated further. Fourteen rats (group 2) received rabbit anti-BSA antiserum i.v. and i.p. 24 h later. Control groups were injected with uncoated, unmodified latex particles or soluble BSA with and without subsequent antibody administration. Latex was present in the mesangial matrix of rats in group 1 at 1 h in association with a diffuse mesangial distribution of BSA. At 24 h, BSA staining was markedly reduced and extracellular latex was no longer observed. Intracellular latex aggregates were present in experimental and control groups at 24 h-14 days in cytoplasmic vacuoles of hypertrophic mesangium which showed minor infiltration by macrophage-like cells. Progressive removal of latex aggregates coincided with declining mesangial reactivity. Rapid disappearance of antigen apparently results from local degradation of tracer in the mesangium. Antibody administration preserves BSA in the mesangium due to immune complex formation and is associated with retention of ingested latex by mesangial cells. However, efficient disposal of glomerular immune deposits by the mesangium appears to minimize infiltration by monocytes and prevents aggravation of glomerular inflammation.

Animals↗
PubMed1985

Microthrombus formation on hemodialysis membranes: a placebo controlled randomized trail of two doses of Indobufen.

The role of Indobufen in preventing the formation of microthrombi on hemodialysis membranes has been investigated in 18 patients in a placebo controlled randomized double-blind cross-over study. All patients had been on regular maintenance hemodialysis for at least 3 months. Indobufen was given as 100 mg b.d. and 200 mg b.d. each for a 7 day period with a 7 day wash-out period between the treatments. Both Indobufen regimens prevented the fall in platelet count, reduced the increase in plasma BTg levels during dialysis, increased the post dialysis plasma heparin levels (p less than 0.05) and inhibited pre-dialysis platelet aggregation with collagen (p less than 0.05), when compared with placebo treatment. Scanning electron microscopy demonstrated minimal fibrin and reduced platelet deposition following Indobufen treatment. There was no difference in the effect of 100 mg b.d. and 200 mg b.d. Indobufen doses. The drug was well tolerated, despite the relatively high levels measured, only one patient withdrew because of side effects. This study indicates that Indobufen when added to a routine hemodialysis treatment schedule, can significantly reduce platelet activation and the thrombus formation on the hemodialysis membranes.

Blood Platelets↗
PubMed1984

CAPD--a risk factor in renal transplantation?

Theoretical considerations suggest that patients undergoing continuous ambulatory peritoneal dialysis (CAPD) may fare less well after renal transplantation than their haemodialysed (HD) counterparts. Review of 121 consecutive cadaveric renal allografts performed in this centre indicate this to be the case with graft survival rates at 1 year of 63.5 per cent in the HD group compared with 35.5 per cent in the CAPD-treated patients. This difference appeared to be independent of the duration of dialysis and, although a significant blood transfusion effect was seen in the HD group, no such trend was evident in the CAPD group. Studies of T cell subsets (using monoclonal antibodies) in the two groups suggests that, in part at least, the differences in graft survival rates may be attributable to the maintenance or restoration of immunological integrity in the CAPD group.

Adult↗
PubMed1984

Persistence of inert macromolecules (Imposil) in the rat mesangium and glomerular functional disturbance.

Imposil iron-dextran is an inert tracer that has been used to study mesangial uptake and clearance of macromolecular material from the glomerular circulation. Such a tracer may be a useful marker of altered mesangial function in animals with some forms of glomerulonephritis. We have studied mesangial handling of intravenously injected Imposil (50 mg/100 g body weight) in normal rats by light, immunofluorescence and electron microscopy for up to 3 months. Mesangial cell uptake was maximal at 48-54 h. Extrusion and drainage of tracer to the vascular pole and distal tubule was evident at 3 days but iron was still present in mesangial cells at 3 months. Possible functional renal impairment resulting from persistent mesangially sequestered tracer was examined by measuring daily urine protein and iron excretion. A possible relationship between failure of mesangial cells to eliminate inert tracer and increasing glomerular permeability is demonstrated, suggesting that Imposil and similar inert macromolecules cannot be used for long-term studies of mesangial function.

Animals↗
PubMed1984

Prevention of platelet deposition and thrombus formation on hemodialysis membranes: a double-blind randomized trial of aspirin and dipyridamole.

A double-blind crossover study comparing low-dose aspirin (ASA) and dipyridamole (DPM) (100 mg ASA + 75 mg DPM, t.d.s.), high-dose ASA and DPM (300 mg ASA + 75 mg DPM, t.d.s.), and placebo on platelet deposition and thrombus formation on hemodialysis membranes was undertaken in 17 long-term dialysis patients. The high-dose combination significantly reduced the fall in platelet count during dialysis and also significantly increased postdialysis heparin concentrations. Scanning electron microscopy of the Cuprophan membranes showed a reduction in platelet deposition and fibrin formation during both treatment schedules, but this was most marked with the high-dose combination. The results of this study indicate that there is a graded response to combined ASA-DPM treatment and that this can significantly reduce platelet consumption and contact activation of fibrin during hemodialysis with Cuprophan membranes.

Adult↗
PubMed1984

Haemodialysis and charcoal haemoperfusion in acute inorganic mercury poisoning.

A 29-year-old gardener developed acute renal failure following the ingestion of 'Mersil', a combination of mercurous and mercuric chloride, achieving a plasma mercury concentration of 22,000 nmol/litre (400 micrograms/litre). Haemodialysis and charcoal haemoperfusion were ineffective in removing mercury despite prior treatment with the chelating agent dimercaprol. The acute renal failure resolved after 10 days and there are no residual sequelae.

Adult↗
PubMed1984

The natural history of renal function in untreated idiopathic membranous glomerulonephritis in adults.

Sixty-four patients (47 male, 17 females) aged between 20 and 70 years with idiopathic membranous glomerulonephritis, never having received steroid or immunosuppressive drugs prior to and subsequent to biopsy, have been followed to terminal renal failure or for a minimum of two up to fifteen years. Presentation was with asymptomatic proteinuria in 12 and nephrotic syndrome in 52. The serum creatinine at time of biopsy was less than or equal to 99 mumoles/l in 25, 100-119 mumoles/l in 18 and greater than or equal to 120 mumoles/l in 21. During the follow up there was no deterioration in renal function in 30 patients (48%). In 27 patients (43.5%) there was a steady deterioration in renal function, on the average 30 months (range 5-60) for the serum creatinine to double and 32 months (range 5-49) for the serum creatinine to reach 400 mumoles/l. In five patients there was a slow deterioration. A plot of the reciprocal of the sequential serum creatinine values with time indicates that the rate of deterioration is essentially constant in any patient but that there is a wide variation between patients. The reciprocal of the serum creatinine is a useful means of following the evolution of the disease. In two patients there was a change in the rate of deterioration and a cause could be identified (one with renal vein thrombosis, one with interstitial nephritis). Poor prognostic indicators were: nephrotic syndrome at presentation, impaired function at time of diagnosis, male patients and older age.

Adult↗
PubMed1983

Haemoperfusion ineffective for paraquat removal in life-threatening poisoning.

Five patients in whom plasma paraquat concentrations suggested that survival was in doubt were treated by charcoal haemoperfusion. The mass of paraquat removed was in each case between 2.5 and 19.1 mg. Three of the patients survived and two died. The mass of paraquat removed is low in relation to the adult lethal dose of 1000-3000 mg.

Evaluation Studies as Topic↗
PubMed1983

Failure of renal dopamine response to salt loading in chronic renal disease.

Eight patients with chronic glomerulonephritis and five age-matched normal volunteers were given additional sodium chloride by mouth under conditions of metabolic balance. Whereas in the normal volunteers plasma renin activity was suppressed and urinary excretion of free dopamine increased, in the patients dopamine was not mobilised and plasma renin activity was not completely suppressed. Abnormal retention of sodium and water in glomerulonephritis may be due partly to a failure to mobilise dopamine in the kidney. Specific renal dopamine agonists may be natriuretic and hypotensive in chronic glomerulonephritis.

Adult↗
PubMed1983

Vitamin A and its transport proteins in patients with chronic renal failure receiving maintenance haemodialysis and after renal transplantation.

Serum vitamin A, retinol binding protein, prealbumin and transferrin have been studied in chronic renal failure patients receiving maintenance haemodialysis and after renal transplantation. Vitamin A and retinol binding protein were uniformly raised in haemodialysis patients and this was unrelated to the period on dialysis. There was a molar excess of retinol binding protein to both vitamin A and prealbumin as compared with normal individuals. Renal transplantation significantly reduces serum vitamin A and retinol binding protein concentrations but has no effect on prealbumin concentrations. The reduction in vitamin A and retinol binding protein is variable in individual patients and cannot be predicted either by the allograft function or time since transplantation. Several years after transplantation, with normal serum creatinine, both serum vitamin A and retinol binding protein levels may still be greatly increased. Despite the very high vitamin A and retinol binding protein concentrations, the close correlation between the two seen in normal individuals is well maintained. The continuing high vitamin A and retinol binding protein levels in patients with satisfactorily functioning transplants is unexplained.

Creatinine↗
PubMed1983

Effects of azepexole on blood pressure, pulse rate, plasma renin activity and urinary catecholamines in normotensive subjects.

Single 5 mg oral doses of azepexole were administered to 6 normotensive male volunteers. Effects on blood pressure and pulse rate were recorded with the subjects supine, erect and during exercise for 8 hours after drug ingestion. Plasma renin activity and urinary catecholamine excretion were measured before and after treatment. Blood pressure was reduced when supine, erect and during exercise. The maximum reduction in systolic and diastolic blood pressure was 20.7 mmHg and 7.9 mmHg, respectively. There was a small reduction in the pulse rate when supine, significant from 2 to 3 hours after drug ingestion. Plasma renin activity increased significantly with drug treatment. There was an insignificant trend towards a reduced urinary catecholamine excretion. Only 1 subject developed significant side-effects. The similarity of azepexole to clonidine is discussed. It is considered that azepexole warrants further study as a hypotensive drug.

Adult↗