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Biomedical subjects

M K Ward

Publications and source records attributed to M K Ward.

At least 55 records · Page 3Linked to original sources
PubMed1989

Oxalate retention in chronic renal failure: tubular vs glomerular diseases.

Plasma oxalate concentration was measured using an enzyme/bioluminescent assay in 289 patients (178 males, 111 females) with chronic renal failure (plasma creatinine greater than 200 mumol/l), age (SD) 55.5 (13.8) years. Plasma oxalate ranged between less than 0.8 and 48 mumol/l and showed a positive correlation with plasma creatinine (r = 0.57, p less than 0.0001). The slope of the regression line in 55 patients with glomerulonephritis (GN) was significantly lower than in patients with tubulointerstitial disease (TI); however the intercept was significantly higher in GN than in TI. Analysis of covariance showed no relationship between plasma oxalate concentration and age, duration of renal impairment, or administration of diuretics, vitamin D analogues, or phosphate binders. Longitudinal analysis of plasma oxalate measured 3-monthly in selected patients showed marked variability of oxalate/creatinine and oxalate/urea ratios.

Adolescent↗
PubMed1988

Critical analysis of the use of skeletal surveys in patients with chronic renal failure.

Skeletal radiology and bone histopathology were compared in 82 patients with renal failure. The performance of radiology in detecting lesions was assessed using interobserver studies which showed disappointing levels of agreement probably reflecting the subjective nature of the radiological signs. Radiology was very insensitive in detecting and grading hyperparathyroidism even when histology and serum biochemistry were floridly abnormal. The most useful radiographs for monitoring subperiosteal erosions and vascular and soft tissue calcification are identified.

Adolescent↗
PubMed1988

Plasma oxalate in patients receiving continuous ambulatory peritoneal dialysis.

Plasma oxalate has been measured in 125 patients maintained on continuous ambulatory peritoneal dialysis using an enzyme/bioluminescent assay. Values ranged between 6 and 134 mumol/l, with a positively skewed distribution. Multiple linear regression analysis with plasma oxalate as the dependent variable showed highly significant associations with the dose of ascorbic acid, dose of alfacalcidol, and plasma creatinine, and weaker associations with serum phosphate, serum calcium, and body weight. When the presence of other potential risk factors was taken into account, no significant relationship could be found between the presence of clinically evident cardiac or vascular disease and plasma oxalate.

Ascorbic Acid↗
PubMed1987

Whole body leucine turnover and nutritional status in continuous ambulatory peritoneal dialysis.

1. Nutritional status and leucine turnover has been measured in ten patients with chronic renal failure before the onset of continuous ambulatory peritoneal dialysis (CAPD) and after 3 months treatment, and in five normal subjects. 2. Somatic muscle protein reserves, as judged by anthropometry and measurement of total body potassium, showed no significant changes after 3 months treatment and were not significantly different from normal. 3. Visceral protein reserves, as judged by serum albumin and plasma amino acids, showed a significant fall after 3 months CAPD and were also lower than in normal subjects. 4. Protein turnover was lower in uraemic than in normal subjects, but the balance between synthesis and breakdown was significantly higher and was maintained after 3 months on CAPD.

Amino Acids↗
PubMed1987

Short-term studies on the use of amino acids as an osmotic agent in continuous ambulatory peritoneal dialysis.

1. A 1% amino acid dialysis solution with a high concentration of the branched-chain amino acids has been compared with 1.36% glucose in short-term studies. 2. The 1% amino acid solution was as effective an agent as 1.36% glucose with respect to ultrafiltration and clearance of creatinine, urea and potassium. 3. Levels of branched-chain amino acids rose to the upper end of the normal range within 1 h and remained at this level over the entire period of the study. Total and non-essential amino acids had returned to baseline by the end of the cycle. 4. Blood glucose rose to significantly greater levels during the 1.36% glucose exchange than during the 1% amino acid exchange. There was an increase in serum insulin levels during both cycles; this was significantly greater with the 1% amino acid solution than the 1.36% glucose. 5. There was no evidence of short-term metabolic complications with the 1% amino acid solution.

Adult↗
PubMed1987

Renal replacement therapy in patients aged over 60 years.

The availability of dialysis for patients with end-stage renal failure in the United Kingdom has lagged behind that in most of the rest of Europe and USA, although there has been considerable improvement over recent years. Concern about prognosis and quality of life on renal replacement therapy, together with shortage of facilities has meant that some elderly people have been denied treatment. A retrospective study of all patients commencing renal replacement therapy in Newcastle between 1974 and 1985 was performed. The five year survival of patients aged more than 60 years at the start of treatment (n = 122) was 53%, compared with 68% for a cohort of individuals aged less than 60 years (n = 632). A questionnaire sent to the 62 elderly patients surviving at the end of the follow-up period revealed that most were married, independent, active and lived in their own home. They were not lonely, generally enjoyed life and were happy with their mode of renal replacement therapy. These results show that elderly patients make good dialysis candidates and they should not be denied treatment on the basis of age alone. Greater funding of renal services is necessary to accommodate these patients.

Age Factors↗
PubMed1987

Haemodialysis-induced respiratory changes.

Eight patients receiving maintenance haemodialysis were studied under six different dialysis protocols, comprising Cuprophan and polyacrylonitrile (PAN 15) membranes, each used with dialysate containing 40 mmol/l acetate, 30 mmol/l acetate or bicarbonate (35 mmol/l), all other constituents being identical. Blood and expired gas determinations as well as transfer factor (DLCO) measurements, serum acetate concentrations, and WBC counts were performed. Rapid reductions in arterial oxygen (PaO2) were observed with Cuprophan (P less than 0.001), and with both strengths of acetate. Polyacrylonitrile used with acetate also demonstrated reductions in PaO2 but these were less severe than those observed with Cuprophan. Bicarbonate buffer resulted in a reduction in the severity of hypoxaemia, but failed to totally eliminate its occurrence. Hypoventilation was observed with both strengths of acetate dialysates, but not with bicarbonate. The respiratory exchange ratio decreased by 25% as a result of decreases in lung CO2 excretion when using acetate. Transfer factor declined by 40% for Cuprophan compared with 14% with polyacrylonitrile (P less than 0.01). Leucopenia was more severe with Cuprophan than with polyacrylonitrile. We conclude that amelioration of hypoxaemia may be achieved by the use of bicarbonate, but its cause is multifactorial, with contributions from hypoventilation secondary to dialyser CO2 losses and pulmonary dysfunction due to leucostasis. These observations suggest that the treatment of patients who have compromised cardiovascular function is most optimal with the use of biocompatible membranes which induce minimal leucopenia, used in conjunction with dialysate that utilises bicarbonate as the base replacement.

Blood Gas Analysis↗
PubMed1986

Continuous ambulatory peritoneal dialysis after the honeymoon: review of experience in Newcastle 1979-84.

Two hundred and twenty nine consecutive patients (129 men, mean age 45) were reviewed 12 to 65 months after starting treatment with continuous ambulatory peritoneal dialysis (CAPD) from January 1979 to December 1983. They received CAPD for a mean of 19.8 (range 0.5-62) months. Actuarial patient survival was 79% at 24 months and 72% at 36 months. Half of the 46 deaths were related to cardiovascular disease, while eight patients died of abdominal complications, including three patients with peritonitis. Peritonitis occurred at a rate of one episode per 35 patient weeks, and 88% of episodes were cleared by one or more courses of antibiotics. This still left peritonitis as the commonest cause of failure of CAPD, leading to a permanent change of treatment in 44 patients and temporary interruption in a further 25. CAPD remains a reasonable medium term treatment in chronic renal failure. Despite the persisting problem of peritonitis the results are comparable with those achieved by haemodialysis, and CAPD has become the treatment of first choice for end stage renal failure in Newcastle. In younger patients judged unsuitable for transplantation and facing long term dialysis, however, haemodialysis is preferred.

Actuarial Analysis↗
PubMed1986

Serum calcium status in health and disease: a comparison of measured and derived parameters.

The relationship of serum ionised calcium to total calcium was investigated in three series of experiments, each using different ion-selective electrodes. In the first, total and ionised calcium were measured in healthy and patient groups to compare the predictive value of each estimation. In the second and third studies, measured ionised calcium was compared with ionised calcium calculated using 5 different formulae, and with total calcium, both uncorrected, and adjusted for varying protein content using eight formulae. In 144 of 149 healthy subjects, serum ionised calcium and total calcium were normal. There were discrepancies between serum ionised calcium and total calcium in 135 of 572 patients with conditions associated with abnormal calcium metabolism. Correction of total calcium, or calculation of ionised calcium did not significantly improve this figure. Thus, corrected or derived calcium values will not substitute for ionised calcium determination in patients with abnormal calcium metabolism.

Arthritis, Rheumatoid↗
PubMed1986

Evaluation of glycerol as an osmotic agent for continuous ambulatory peritoneal dialysis in end-stage renal failure.

Six patients established on continuous ambulatory peritoneal dialysis entered a trial of treatment with dialysis fluid containing glycerol instead of glucose as the osmotic agent in an attempt to decrease the energy load. They were observed for a further 6 months after reconversion to glucose-based dialysis. During the 6 month control period fluid balance was achieved mainly with a solution containing 76 mmol of glucose/1. Fluid balance was maintained during the 6 month period of treatment with glycerol only by the increased use of solutions containing a high concentration of glycerol (152 mmol/l and 272 mmol/l). Thus the energy value of the absorbed osmotic agent did not differ at a mean of 1607 kJ (384 kcal)/day using glycerol and 1669 kJ (399 kcal)/day using glucose as the osmotic agent. In five subjects, fasting and peak blood glycerol levels did not change over the 6 months, but one subject, who accumulated glycerol, developed symptoms of hyperosmolality after 2 months and glycerol therapy was discontinued. In a further subject glycerol-based dialysis was terminated at 3 months when increasing angina was reported. Mean fasting plasma triglyceride concentrations were 50% higher during the 6 months on glycerol (3.12 +/- 1.12 mmol/l) than on glucose (2.19 +/- 0.97 mmol/l) (P less than 0.05). There was a small rise in very low density lipoprotein-cholesterol concentrations with glycerol dialysis but total cholesterol levels were unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Haemodialysis-induced activation of complement. Effects of different membranes.

The ability of cellulose-based (Cuprophan, saponified cellulose ester) and synthetic (polyacrylonitrile, polycarbonate, polymethylmethacrylate) haemodialysis membranes to activate complement during treatment was compared, using functional, immunochemical, radioimmunoassays, and fast centrifugal analysis assay techniques. Cellulosic and synthetic membranes show a striking similarity in their complement activation when measured by immunochemical assays. Functional haemolytic assays for alternate pathway and CH50 demonstrate no significant differences from predialysis values. C3d levels were also unable to demonstrate differences between the membranes. C3a levels, on the other hand, demonstrated significant differences between cuprophan, polyacrylonitrile, and polymethylmethacrylate but not between Cuprophan and polycarbonate membranes. Since comparable alternate-pathway activity of both cellulosic and synthetic membranes was demonstrated, but their C3a release differed, it is possible that certain surfaces that activate complement also possess the ability to absorb components of the alternate pathway.

Acrylic Resins↗
PubMed1986

Anterior pituitary dysfunction in patients with chronic renal failure treated by hemodialysis or continuous ambulatory peritoneal dialysis.

Cortisol, prolactin, and growth hormone responses to insulin-induced hypoglycemia were measured in 20 patients undergoing continuous ambulatory peritoneal dialysis or intermittent hemodialysis. The plasma cortisol responses were normal; however, the increments in serum prolactin and growth hormone concentrations were impaired in most patients. The growth hormone responses were lower (p less than 0.05) in those patients treated by continuous ambulatory peritoneal dialysis, but there were no other significant differences between the two patient groups. These results show that anterior pituitary dysfunction persists in some patients with chronic renal failure despite maintenance dialysis therapy.

Adolescent↗
PubMed1986

Hypothalamic-pituitary-adrenocortical suppression and recovery in renal transplant patients returning to maintenance dialysis.

Sixty-six per cent of a group of 21 renal transplant recipients with chronic renal failure were shown to have adrenal suppression due to glucocorticoid treatment. Gradual withdrawal of steroids in these patients returning to maintenance dialysis therapy was achieved with few symptoms of hypoadrenalism. Adrenal recovery occurred in 52 per cent of patients after three months and 71 per cent after six months. However, the plasma cortisol response to insulin-induced hypoglycaemia, studied in patients in whom adrenal recovery had been demonstrated, was impaired in 46 per cent of cases. These results indicate that corticosteroids in renal transplant recipients induce profound hypothalamic-pituitary-adrenal suppression which is slow to recover. Such patients returning to maintenance dialysis are at risk of acute adrenocortical insufficiency for several months. Although withdrawal of steroids can be achieved safely, cover during periods of stress should be given until the hypothalamic-pituitary-adrenal axis has been shown to respond normally.

Adolescent↗