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Biomedical subjects

W K Stewart

Publications and source records attributed to W K Stewart.

At least 37 records · Page 2Linked to original sources
PubMed1992

Dextran antibodies, complement conversion and circulating immune complexes after intravenous iron dextran therapy in dialysed patients.

Serum immune complexes, plasma dextran antibodies and percentage conversion of complement have been measured in 20 dialysed patients before and after an intravenous infusion of iron dextran providing 600 mg elemental iron. Complement conversion was unmeasurable and there were no changes in circulating immune complexes. The presence of dextran antibodies in nine patients before the infusion was not related to prior exposure to iron dextran. They became undetectable in these patients within hours after the infusion, reappearing 1 month later in three. Two of three patients reporting mild aches and shivers on the day following the infusion had no detectable dextran antibodies. An adverse reaction involving inflamed joints occurred 1-2 days after a second infusion given to one of the patients studied above. The parameters under study were again measured and did not appear to relate to the reaction. The presence of dextran antibodies does not preclude the giving of iron dextran to patients on dialysis, and the immune complex and complement systems remain undisturbed by iron dextran infusions.

Adolescent↗
PubMed1992

Dialysis efficiency in continuous ambulatory peritoneal dialysis patients treated with erythropoietin.

OBJECTIVE: To determine the effect of subcutaneous erythropoietin treatment on dialysis efficiency in continuous ambulatory peritoneal dialysis (CAPD) patients. DESIGN: Dialysis efficiency, platelet and white cell aggregation, and red cell deformability were measured monthly for six months in nine anaemic CAPD patients treated with erythropoietin, and on a single occasion in seven control CAPD patients with intrinsically high haemoglobin concentrations. SETTING: Renal dialysis unit. PATIENTS: Nine patients stable on CAPD for a minimum of six months and with haemoglobin concentrations less than 8.5 g/dl were treated with erythropoietin. Seven CAPD patients matched for age and renal function, with haemoglobins greater than 9.0 g/dl served as controls. RESULTS: Daily peritoneal clearances and net ultrafiltration volumes were unchanged when haematocrit increased from 25.0 +/- 2.2% to 36.5 +/- 3.5%. Spontaneous whole blood platelet aggregation was significantly increased from week twelve (pre-treatment aggregation 46 +/- 23%; 12 weeks: 67 +/- 19%, p less than 0.05; 16 weeks: 64 +/- 19%, p less than 0.01; 20 weeks: 71 +/- 16%, p less than 0.01; 24 weeks: 73 +/- 10%, p less than 0.01). CONCLUSIONS: The increase in haematocrit and platelet aggregation associated with erythropoietin treatment did not affect peritoneal clearances or ultrafiltration capacity.

Anemia↗
PubMed1992

Lipid peroxidation and antioxidants in continuous ambulatory dialysis patients.

OBJECTIVE: Oxidative cell damage due to the production of free radical species has been implicated in the pathogenesis of cardiovascular disease for which dialysis patients are at increased risk. Plasma lipid peroxides (malon-dialdehyde), the antioxidants plasma albumin thiol, and red cell superoxide dismutase (SOD) were therefore measured in 18 patients undergoing continuous ambulatory peritoneal dialysis (CAPD), 20 hemodialysis patients, and 30 normal controls. SETTING: Renal dialysis unit. RESULTS: Malondialdehyde (MDA) concentrations were significantly higher in dialysis patients compared to controls (p less than 0.001) and were significantly higher in CAPD patients compared to hemodialysis patients, p less than 0.001 (CAPD, median and range: 11.25 (8.4-15.5) nmol/mL; hemodialysis: 8.75 (7.0-12.6) nmol/mL; controls: 6.65 (5.2-9.6) nmol/mL). Plasma thiol and red cell SOD were significantly lower in dialysis patients compared to controls, but there was no significant difference between CAPD and hemodialysis patients (CAPD thiol: 333.5 (282-480) mumol/L; hemodialysis thiol: 344 (203-468) mumol/L; control thiol: 421.5 (351-504) mumol/L; CAPD SOD: 78.2 (42.4-112.8) u/1/2 mL red cells; hemodialysis SOD: 89.4 (44.6-121.1) u/1/2 mL red cells; control SOD: 96.8 (66.8-153.4) u/1/2 mL red cells). Red cell SOD was significantly negatively correlated with duration of dialysis in CAPD patients (r = -0.683, p less than 0.01). CONCLUSION: In dialysis patients there is indirect evidence for increased free radical activity, which may be further influenced by the mode of dialysis.

Erythrocytes↗
PubMed1991

Erythropoietin and spontaneous platelet aggregation in haemodialysis patients.

Erythropoietin significantly, reversibly, and reproducibly increased in-vitro whole-blood spontaneous platelet aggregation in 15 patients on haemodialysis. During erythropoietin treatment, spontaneous platelet aggregation was significantly higher in these subjects than in non-uraemic controls; concomitant treatment with 300 mg aspirin daily reversed platelet hyperaggregability. Erythropoietin may promote thrombosis by an effect on platelet function.

Anemia↗
PubMed1991

Aluminium content of water for injection used with recombinant human erythropoietin.

Human recombinant erythropoietin is of proven value in the treatment of the anaemia of renal failure. The aluminium content of 36 ampoules of water for injection supplied for use with recombinant erythropoietin has been measured and ranged from 24 to 450 micrograms/l, with a median of 251 micrograms/l. In three samples, which may have been contaminated on opening, the range was from 1770 to 6160 micrograms/l. In Water for Injection BP, values ranged from 66 to 140 micrograms/l with a median of 99 micrograms/l. Reconstituted erythropoietin did not contain any more aluminium than could be accounted for by the water. Ampoules of a second brand of erythropoietin, supplied already in solution, contained from 506 to 837 micrograms/l aluminium (median 682 micrograms/l). In view of the lifelong duration of erythropoietin therapy clinicians and pharmaceutical companies should be aware of this potential problem. Although the amount of aluminium delivered with each injection is usually less than 4 micrograms, it is suggested that active steps are taken to establish a British Pharmacopoeia limit on the aluminium content of injections.

Aluminum↗
PubMed1991

Whole blood granulocyte aggregation in vitro in dialysis-dependent patients.

Whole blood granulocyte aggregation in vitro was measured in 17 haemodialysis (HD) patients, 18 continuous ambulatory peritoneal dialysis (CAPD) patients, and 30 age-matched normal controls. Granulocyte aggregation was significantly increased in dialysis-dependent patients compared to controls (P less than 0.001) and was statistically significantly higher in CAPD patients compared to HD patients (P less than 0.01). [CAPD patients, median (range): 56.5 (44-71)%; HD patients: 53.0 (32-67)%; Controls; 42.5 (33-56)%.] Since granulocyte hyperaggregability has been linked with the pathogenesis of ischaemic vascular disease, abnormal granulocyte activity in dialysis-dependent patients may be of many factors contributing to their increased cardiovascular morbidity.

Adult↗
PubMed1990

Oral ciprofloxacin in the treatment of peritonitis in patients on continuous ambulatory peritoneal dialysis.

Oral ciprofloxacin in doses of 0.75 to 2 g daily for 8-16 (median 10) days was given as first-line treatment of 33 unselected episodes of CAPD-associated peritonitis in 20 patients. Treatment was well tolerated and effective, curing 25 episodes. Treatment was withdrawn in five episodes, four because of resistant organisms and in the other because of vomiting. Infection relapsed twice in one patient during follow-up and one patient had persistence of the infecting organism (Pseudomonas aeruginosa) despite clinical improvement. Plasma and dialysate ciprofloxacin levels ranged from 1 to 8 mg/l. Assay between days 2 and 4 of treatment indicated the ciprofloxacin steady state concentration. If this proves to be greater than 7 mg/l the dose may be reduced and if less than 2 mg/l the dose should be increased. Overall a single course of oral ciprofloxacin was 76% successful as a first-line treatment for CAPD-associated peritonitis, caused by a wide range of organisms.

Administration, Oral↗
PubMed1990

Hepatic iron in dialysed patients given intravenous iron dextran.

Five percutaneous biopsy and 17 necropsy liver specimens were analysed histologically and chemically for iron content in 22 patients receiving dialysis for chronic renal failure, 13 of whom were given intravenous iron-dextran. Brissot scores for assessing histological hepatic iron deposition and chemically measured liver iron concentrations correlated closely. Both variables depended on total cumulative dose of iron, and to a lesser extent, on time since the last dose. Fibrosis (seen in five patients) was minimal and non-specific. Electron microscopic examination showed that there was no generalised damage and confirmed the presence of iron in the hepatocytes in the form of ferritin. High liver iron concentrations, in excess of 1000 micrograms/100 mg dry weight, were seen in two patients. Four others given comparable cumulated amounts (18-23 g iron) did not have such high concentrations. Plasma ferritin concentrations were high in eight patients, some with and some without fibrosis. The risk of temporarily high iron deposition in the liver causing damage seemed to be minimal when weighed against the benefit of increased haemoglobin in most of the patients. Intravenous iron treatment merits further evaluation, particularly with the advent of erythropoietin treatment, which requires continuously available iron.

Adult↗
PubMed1990

Calcium carbonate 1250 mg/1260 mg: an effective phosphate binder.

Calcium carbonate is currently the first choice phosphate binder in renal failure. In the UK its most widely prescribed formulation is a combination of calcium carbonate 420 mg and glycine 180 mg (Titralac 3M Riker). In order to achieve adequate reduction in the serum phosphate level, up to 12 of these tablets may be required daily. In a group of seven patients, we have compared Titralac with two alternative preparations containing calcium carbonate 1250 mg (Calcium-500 Macarthy's Medical Ltd) and calcium carbonate 1260 mg (Calcichew Shire Pharmaceuticals Ltd). Given at a third of the daily number of Titralac tablets, both these newer preparations were effective phosphate binders and produced no statistically significant change in serum calcium and phosphate. The important advantage of such a reduced tablet load is improved patient compliance with phosphate binder therapy. Calcium-500 is also a cost-effective treatment slightly reducing the cost when compared with combined calcium carbonate 420 mg and glycine 180 mg.

Adult↗