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Biomedical subjects

P C Sizeland

Publications and source records attributed to P C Sizeland.

11 recordsLinked to original sources

Short-term response of nonurea organic osmolytes in human kidney to a water load and water deprivation.

The cells of the inner medulla of the mammalian kidney accumulate high concentrations of nonurea organic osmolytes. The organic osmolytes found in the kidney include glycine betaine and sorbitol. This study was designed to measure changes in the urinary excretion of glycine betaine and sorbitol and the plasma concentration of glycine betaine in response to an acute water load (20 ml/kg) or acute water deprivation in young healthy males. In response to a water load the urinary excretion of glycine betaine and sorbitol increased parallel with or shortly after urinary urea excretion. The increase in urinary urea and sorbitol excretions preceded maximum minute volume, whereas peak glycine betaine excretion was closely related to maximum urine minute volume. Subsequently, urea, sorbitol, and glycine betaine excretion rates returned to baseline. In contrast, during water deprivation no change in glycine betaine, sorbitol, and urea urinary excretions occurred during the study period. Plasma glycine betaine concentration was stable during both diuresis and antidiuresis. We conclude that the organic osmolytes glycine betaine and sorbitol are components of a physiological and dynamic system in response to an acute water diuresis.

Adult↗

Abnormal glycine betaine content of the blood and urine of diabetic and renal patients.

In normal human plasma the concentrations of the renal osmolyte, glycine betaine, are usually between 20 and 70 mumol/l, in adult males (median 44 mumol/l) higher than in females (34 mumol/l). Concentrations are lower in renal disease (median 28 mumol/l) and normal in diabetes. Urinary excretion of glycine betaine shows no sex difference and is frequently elevated both in renal disease and in diabetes (medians: normal, 6.2, renal 12.3 and diabetes, 39.7 mmol/mol creatinine). The elevation in diabetes does not strongly correlate with known renal disease, nor with either urinary microalbumin or plasma creatinine. There is no correlation with glycated haemoglobin. The positive correlation with the excretions of another renal osmolyte, sorbitol, was highly significant in diabetic subjects. In the diabetic group there was also a significant negative correlation between plasma glycine betaine and urine microalbumin.

Adult↗

Glycine betaine and proline betaine in human blood and urine.

In healthy human subjects, glycine betaine concentrations in the blood plasma are normally between 20 and 60 mumol/l, adult males tending to have higher concentrations than females. Proline betaine concentrations are more variable, ranging from undetectable to about 50 mumol/l. Both betaines are present in urine. Whereas the urinary excretion of proline betaine reflects plasma concentrations, with high clearance rates, there is no correlation between plasma and urine glycine betaine concentrations. The apparent clearance rates are low (usually less than 5%). The proline betaine content of human kidney tissue is less than 0.1% of the glycine betaine content, and this is true also of rabbit tissue despite high concentrations of both betaines in rabbit circulation and urine. These data suggest that glycine betaine, but not proline betaine, is important in human and other mammalian biochemistry.

Adolescent↗

Organic osmolytes in human and other mammalian kidneys.

Osmotically-active organic solutes, or osmolytes, have been found in high concentration in the renal inner medulla of a wide variety of mammalian species, but their existence in human kidneys has not yet been shown. The aim of this study was to demonstrate the presence of osmolytes in the human kidney. Human tissues were obtained from kidneys removed surgically for diseases which involved only one pole of the kidney; in most cases this was a tumor. Animal kidneys analyzed were from dogs, pigs and rabbits. Inner medulla and cortex tissue samples were analyzed and found to contain the organic osmolytes glycine betaine, myo-inositol, sorbitol and glycerophosphorylcholine. The levels were much higher in the medulla than in the cortex. Further dissection of the human kidneys showed that sorbitol, glycerophosphorylcholine and glycine betaine were maximally concentrated at the papillary tip, while myo-inositol was found in highest concentration at the papillary base. Osmolytes were in low concentrations or undetectable in rabbit skeletal muscle, ureter and bladder. The organic osmolytes detected are likely to be physiologically important in humans. Studies in other mammals can be used as models for the investigation of the osmolyte system in human kidney function.

Animals↗

Epstein-Barr virus infection acquired from a cadaveric renal transplant.

A 42-year-old man, seronegative for Epstein-Barr virus (EBV), received a cadaveric renal transplant. Serology from the 27-year-old male donor indicated an active EBV infection. Following treatment for acute rejection with OKT3 the recipient developed a severe systemic illness. Clinical features strongly suggested an acute EBV infection and serology showed seroconversion for EBV. The patient died and autopsy histology revealed widespread polymorphic lymphocyte infiltration in lymph nodes and solid organs. To our knowledge this is the first report of a kidney being transplanted from a donor who was subsequently shown to have had EBV infection at the time of organ retrieval. The EBV status of an organ donor should be considered more frequently.

Adult↗

Wegener's granulomatosis with renal involvement: a 14 year experience.

Over a 14 year period 17 patients (nine men) with Wegener's granulomatosis and renal involvement had a renal biopsy. All patients had a necrotising glomerulonephritis and 15 had evidence of crescent formation in glomeruli. Fourteen patients were treated with both prednisone and cyclophosphamide and three with prednisone and azathioprine. The five year patient survival rate was 73% and the renal survival rate 68%.

Adult↗

Anemia and angiotensin-converting enzyme inhibition in renal transplant recipients.

The renin-angiotensin system has been shown to have an effect on erythropoietin synthesis and hemoglobin concentration. We present a retrospective study of stable renal transplant recipients who received an angiotensin-converting enzyme (ACE) inhibitor as treatment of hypertension. Fifteen patients were eligible, with a mean hemoglobin concentration of 130.7 +/- 22.7 g/L (SD). Within 6 months of ACE-inhibitor therapy, the mean hemoglobin had fallen significantly to 110.5 +/- 23.2 g/L (p less than 0.001). No parallel change in leukocyte or platelet counts was evident. Prospective studies are needed to clarify the effect of inhibition of the renin-angiotensin system on erythropoietin synthesis and release.

Anemia↗

Asthma: a provincial study.

To identify factors contributing to increased mortality and morbidity we prospectively evaluated 200 consecutive adult (greater than 17 years) asthmatic presentations (105 patients) referred to Gisborne Hospital over a 28 month period between 1985 and 1987 using a modified protocol adapted from previous national studies. In the moderate asthmatic group (113 presentations, 56%), 6% failed to use beta agonists prior to admission and 43% were not on regular steroid inhaler therapy. No patient had a crisis plan although 45 (22.5%) had received oral steroid therapy before admission. Poor drug compliance was twice as common in the Maori. Fifty-eight percent of patients were on regular long term oral theophylline whereas 48 (43%) patients with moderate and severe asthma were not on corticosteroid inhalers. We conclude that patient education and more liberal use of steroid inhalers have the greatest potential for improving morbidity and mortality.

Administration, Inhalation↗