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Biomedical subjects

J Walls

Publications and source records attributed to J Walls.

223 records · Page 13Linked to original sources

Analysis of patients dying within one year of starting renal replacement therapy.

BACKGROUND: The annual gross mortality of end-stage renal failure patients remains very high (approximately 15-20%) leading some to question the wisdom of accepting patients with limited prognosis for dialysis. We have reviewed the demographic and clinical characteristics of patients who died within a year of commencing renal replacement therapy (RRT) over a 5-year period to establish whether these patients could be identified at the start of therapy. METHODS: Case notes of patients who died within 1 year of commencing RRT between 1st April, 1991 and 31st March, 1996 were reviewed. Comorbidity at the start of dialysis was used to classify patients into high-, medium- and low-risk groups using two published scales to determine whether either graded a high proportion of deaths as high risk. Factors such as age, social circumstances, cause of death, renal diagnosis and mode of dialysis were also analysed. RESULTS: 17.5% of patients commencing RRT died in the first year. Not all of these patients could be identified as high risk by comorbidity assessment at dialysis initiation - 50% of patients who died were classified by one scale as medium risk. Age did not clearly predict outcome, as 42% of patients who died were less than 65 years old. CONCLUSION: These data suggest that it is difficult to use current risk stratifications to accurately predict outcome on RRT.

Adolescent↗

Hypertrophy of proximal tubular epithelial cells induced by low pH in vitro is independent of ammoniagenesis.

Metabolic acidosis can lead to tubular hypertrophy in vivo. This is thought to arise from stimulation of renal production of ammonia, a known hypertrophic agent. To examine this effect in vitro, confluent opossum (OK) proximal tubular epithelial cells were cultured at acidic pH (7.21 +/- 0.02) or at control pH (7.37 +/- 0.01) for 4 days. Protein content was 9% higher at acidic pH whereas DNA content was unaffected. The resulting increase in mean cell size (protein/DNA ratio) was 10% but correlated inversely with the mass of cells in control wells, varying from +48% at low cell mass to -14% at high cell mass. In contrast, low pH decreased 3H-thymidine incorporation by 9%. However, ammonia production was unaffected. These changes in protein/DNA ratio and 3H-thymidine incorporation cannot therefore be attributed to acid-induced ammoniagenesis and imply that low pH exerts a more direct effect on tubular cell growth than previously envisaged.

Ammonia↗

Growth of proximal tubular cells in the presence of albumin and proteinuric urine.

The degree of interstitial scarring and proteinuria both correlate with renal function in progressive renal disease. Cellular hypertrophy and hyperplasia have been shown to occur under different experimental conditions. This study investigated the effect of protein on the growth of OK cells. Bovine serum albumin (BSA)- and fatty-acid-free BSA (FFBSA)-stimulated proliferation of OK cells and hypertrophy occurred when the cells were incubated with 10 mg/ml of BSA or FFBSA. Incubation with proteinuric urine from nephrotic rats resulted in much greater proliferation. Hence protein can alter proximal tubular cell growth in culture and the mixture of proteins in proteinuric urine has a greater effect than can be explained by albumin alone. These findings may be of significance in the progression of renal disease and indicate the potential importance of urinary proteins other than albumin in modulating tubular cell growth.

Animals↗