Clinical comparison of high-flux cellulose acetate and synthetic membranes.

Solute transport and alterations in complement and clotting induced by a new high-flux cellulose acetate membrane (CA-HF800-E, Diaphan) were compared with those for cellulose triacetate (CTA) and polysulphone in a cross-over clinical study. The membranes are similar in their small-molecule removal. Serum beta 2-microglobulin decreased with all membranes but the decrease was independent of membrane type. Associated with beta 2-microglobulin removal was a protein loss which averaged 2636 mg for Diaphan, 4937 mg for CTA, and 2500 mg for polysulphone. Albumin presence in the dialysate was less than the limit of detection (5 mg/l) but for each of the membranes, occasional readings above the limit of detection were noted. C3a generation for Diaphan is comparable with that for CTA and polysulphone, but differed for C5a and neutropenia. A highly significant correlation of the area under the concentration time curve of the two complement components was noted for the cellulose based membranes (r = 0.875, P = 0.0002 for Diaphan, r = 0.823, P = 0.006 for CTA) this relationship was less marked for polysulphone (r = 0.396, P = 0.29). Induction of clotting characterized by the thrombin-antithrombin III (TAT) complex were similar for the three membranes, as were changes in platelet counts. Our findings indicate that while it is possible to modify cellulose to produce a membrane whose solute transport and biocompatibility is similar to synthetic membranes such as polysulphone, the structural modifications induce considerable differences in the amount of protein lost.

Assessment of chemotherapy-associated nephrotoxicity in children with cancer.

Assessment of the toxicity caused by chemotherapy in children with cancer has become more important as the number of long-term survivors has continued to increase. It is vital to monitor both acute life-threatening adverse effects and long-term toxicity that may impair the child's development and cause permanent morbidity. Renal damage may follow treatment with cytotoxic drugs, especially cisplatin or ifosfamide, and lead to glomerular, proximal tubular or distal tubular impairment or to any combination of these. Greater understanding of nephrotoxicity and of its prevention may enable the use of more intensive schedules or of higher doses of potentially nephrotoxic chemotherapy. However, the evaluation of cytotoxic drug-induced nephrotoxicity has frequently depended mainly on measurement of the plasma creatinine concentration, which may remain normal despite substantial glomerular impairment or severe tubular dysfunction. Detailed assessment of nephrotoxicity depends on an understanding of normal renal physiology and requires evaluation of all aspects of function. A comprehensive but simple investigatory protocol that enables assessment of the nature and severity of nephrotoxicity in children is described, which can be performed without admission to hospital. Glomerular function is assessed by measurement of the glomerular filtration rate from the plasma clearance of [51Cr]-ethylenediaminetetraacetic acid ([51Cr]-EDTA). Proximal nephron function is evaluated in three ways: by measurement of the concentration of calcium, magnesium, phosphate, glucose and urate in blood and urine along with calculations of their fractional excretion and of the renal threshold for phosphate; by determination of the excretion in urine of low-molecular-weight proteins (e.g. retinol-binding protein); and by investigation of urinary bicarbonate excretion in patients who are acidotic. Distal nephron function is initially investigated by examination of the concentration (osmolality) and acidification (pH) of an early morning sample of urine. Finally, a group of general investigations is performed, including quantitation of urinary excretion of renal tubular enzymes (e.g. N-acetylglucosaminidase) and measurement of blood pressure.

Investigation of the use of bilirubin oxidase to measure the apparent unbound bilirubin concentration in human plasma.

An investigation into the use of bilirubin oxidase to measure the apparent concentration of unbound bilirubin in solutions of bilirubin or bilirubin/human serum albumin demonstrated (1) near linearity of oxidation rate with bilirubin concentration up to 16 mumol/L, (2) linearity with respect to enzyme concentration up to 75 mg/L, (3) specificity of the enzyme for unbound bilirubin, as opposed to bound bilirubin, (4) poor precision. Very small absorbance changes leading to poor precision and the potential for interference by conjugated bilirubin meant that the method was unsuitable for patient samples.

Plasma osmolality, sodium, and urea in healthy breast-fed and bottle-fed infants in Newcastle upon Tyne.

Dale, G., Goldfinch, M. E., Sibert, J. R., and Webb, J. K. G. (1975). Archives of Disease in childhood, 50, 731. Plasma osmolality, sodium, and urea in healthy breast-fed and bottle-fed infants in Newcastle upon Tyne. Plasma osmolality, sodium, and urea were measured on samples from 50 healthy infants, aged between 18 and 125 days, attending child health clinics in Newcastle upon Tyne. 3 infants had osmolalities greater than 300 mOsm/kg, a lower incidence of hyperosmolality than that previously reported. There was a difference (P less than 0-001) between the plasma urea levels of breast-fed and bottle-fed infants, but not between the osmolalities of these groups. The mean plasma urea of bottle-fed babies was 53 mg/100 ml (SD 12-47), 50-1 mg/100 ml (SD 10-9) if additional solids were being given, and 18-4 mg/100 ml (SD 7-81) for breast-fed babies. There was little difference between the plasma sodium levels of each group. The mean plasma sodium for all groups combined was 135-2 mmol/1 (SD 2-3); no plasma sodium exceeded 140 mmol/1.

A comparative study of manual methods for serum triglyeride estimation.

A comparison is made of the accuracy, precision, and convenience of two manual serum triglyceride methodologies based on solid phase adsorption and liquid phase partition procedures. Both methods are accurate but the precision and convenience of the latter is far superior. The use of home made reagents reduces the cost of both substantially below that of any commercial alternative, including the popular enzymatic methods.