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Biomedical subjects

L W Fleming

Publications and source records attributed to L W Fleming.

At least 37 records · Page 2Linked to original sources
PubMed1989

Chemical reactivity of aluminium-based pharmaceutical compounds used as phosphate-binders.

Several aluminium-containing substances, including antacids used as phosphate-binders in treating renal failure, have been analysed in-vitro under different pH conditions for the release of Al3+ ions and for binding of phosphate. Control experiments on different forms of pure aluminium hydroxide validated the methods. At pH 2 it was the most amorphous forms which released Al3+ most rapidly. These aluminium ions, available for absorption by the patient, were released from all antacids tested, but no firm phosphate-binding was detected while the pH remained at 2. Phosphate was bound at pH 8, by adsorption onto the surface of aluminium hydroxide. No significant amounts of free Al3+ exist in solution at pH 8, since at that pH aluminium hydroxide is precipitated. The most amorphous forms of this solid were the most efficient phosphate-binders. Alumino-silicate salts require prior exposure to acid to produce free Al3+ before they can act as phosphate-binders, whereas amorphous aluminium hydroxide acts as an efficient phosphate-binder without prior exposure to acid. Chemical principles are employed to show why aluminium release and phosphate-binding are separate and independent processes. Methods are proposed for maximizing the activity of phosphate- binders in-vivo, while minimising aluminium release.

Aluminum↗
PubMed1987

Ciprofloxacin in plasma and peritoneal dialysate after oral therapy in patients on continuous ambulatory peritoneal dialysis.

The quinolone antibiotic ciprofloxacin offers the possibility of effective oral treatment of peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD) if a sufficiently high concentration is attained in peritoneal dialysate. The pharmacokinetics of oral ciprofloxacin have been studied in ten CAPD patients given 250 mg qds for two days. Five patients were being treated for peritonitis with gentamicin and cefuroxime; the remaining five were receiving inpatient training for CAPD or were being treated for other problems. Ciprofloxacin concentration in plasma and in dialysate were determined by HPLC. There were not differences in plasma and dialysate kinetics in patients with and without peritonitis. Plasma levels were higher and the elimination half-life was longer than those reported for healthy subjects. Dialysate and plasma levels were significantly correlated (r2 = 0.87, P = 0.001), with dialysate levels consistently lower than plasma levels. Dialysate levels exceeded 1 mg/l in seven patients. The mean peak dialysate level (2.17 +/- 1.63 mg/l) exceeded the MIC of ciprofloxacin for 32 of 34 bacterial strains responsible for peritonitis. Ciprofloxacin shows promise as a useful oral treatment of CAPD-associated peritonitis.

Administration, Oral↗
PubMed1987

Perthshire pioneer of anti-inflammatory agents (Thomas John Maclagan).

The achievements of Thomas John Maclagan (1838-1903) include the first specific use of salicin to cure acute articular rheumatism. He began salicin treatment in 1874 in Dundee, where he was a medical practitioner from 1869 to 1879. Maclagan was also the resident medical superintendent at Dundee Royal Infirmary from 1864-1866, where he was the first in Scotland to make investigative use of the clinical thermometer during the fever epidemics. From 1879-1903 he maintained a fashionable practice in London. His contributions to medicine and in particular to the development of aspirin, once ranked as equivalent to the achievements of Lister and Simpson, have now largely been forgotten. This account is a tribute to a life rich in individual endeavour, observation and effort before the "teamwork" era began.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1986

Patient load and medical staffing in adult dialysis units in the United Kingdom.

A survey of medical staffing in 50 adult dialysis units in the United Kingdom in 1986 showed a wide range of patient to staff ratios or staffing score ratios. The total patient load (patients receiving haemodialysis in hospital and at home and those receiving continuous ambulatory peritoneal dialysis) varied from 12 to 270 per unit. Patients receiving acute haemodialysis or who had received a transplant were not included. The unit staffing score, on a weighted scale based on experience, varied from 6.0 to 40.5. Previous surveys have all been regionally or nationally based so criteria for assessing the adequacy of staffing in single units do not exist. This survey attempts to provide a guideline by describing the range of medical staffing compared with patient load in single dialysis units. No unit considered itself to be overstaffed, and several considered themselves to be greatly understaffed. Individual dialysis units should plead their own case in the light of their own circumstances and up to date information provided in nationwide staffing surveys such as this one.

Data Collection↗
PubMed1984

Bone marrow iron and plasma ferritin in dialysed patients given intravenous iron-dextran.

Bone marrow biopsies have been taken in 28 patients on or approaching maintenance haemodialysis before and after treatment with monthly intravenous iron-dextran (Imferon). Stainable marrow iron was compared with blood Hb, plasma ferritin, erythrocyte protoporphyrin and MCH levels at the time of biopsy, and with previous or subsequent responses to iron in terms of blood Hb and MCH. There was a positive correlation between bone marrow iron and plasma ferritin levels both before and after iron therapy. All the patients with excess marrow iron had high plasma ferritin. However, six patients with low or normal marrow iron also had high plasma ferritin, two of these before iron therapy was given. Seven of the eight patients with no detectable marrow iron had low plasma ferritin. Three of the 28 patients failed to respond to iron with an increased blood Hb. MCH increased in all patients studied during iron therapy. All but one of the patients with high plasma ferritin prior to iron therapy responded well to iron. Although a good correlation between plasma ferritin and marrow iron can be shown in dialysed patients given intravenous iron-dextran, a high plasma ferritin level in an individual patient should not by itself preclude iron therapy.

Bone Marrow↗
PubMed1982

Plasma retinol and retinol binding protein concentrations in patients on maintenance haemodialysis with and without vitamin A supplements.

Plasma retinol and retinol-binding protein (RBP) concentrations have been estimated in patients on maintenance haemodialysis over a 4-year period. For the first 2 years multivitamin supplements containing vitamin A were taken, and for the second 2 years no vitamin A supplements were given. Mean plasma retinol concentrations decreased significantly but only from 3.8 times normal to 3.1 times normal after vitamin A supplements stopped. There was no significant change in th high plasma RBP levels. Ultracentrifugation of plasma at a salt density of 1.21 showed that nearly all the retinol was associated with RBP in the high density protein fraction, as it is with normal subjects. Column chromatography confirmed that there was no increase in plasma retinyl esters in the renal failure patients, as is found in hypervitaminosis A due to drug overdosage. The high plasma retinol and RBP levels remained remarkably stable in individual patients throughout the 4-year study. The increase in plasma RBP was possibly related to residual urine output. The results are compatible with a feedback mechanism whereby the extent of the increase in plasma RBP as renal failure develops controls the consequent high plasma level of retinol.

Anuria↗
PubMed1982

Improved phosphate clearances with polycarbonate membranes.

Clearance studies of urea, creatinine and inorganic phosphate have been carried out using polycarbonate dialysers on 20 occasions in two patients undergoing routine maintenance haemodialysis. Clearances were calculated using plasma concentrations and both measured blood flow and calculated plasma flow. Urea and creatinine clearances were comparable to those obtained with cellulose-based dialysers, but phosphate clearances were relatively increased, averaging over 70% of urea clearances. All clearances were reduced as TMP values increased, a feature at variance with the usual situation with cellulose membranes. Polycarbonate dialysers have the advantage of higher relative phosphate clearances in addition to the other advantages claimed for them.

Cellulose↗
PubMed1982

The effect of oral aluminium therapy on plasma aluminium levels in patients with chronic renal failure in an area with low water aluminium.

In a low water aluminium area ( less than or equal to 0.4 micromoles/1) plasma aluminium levels were normal in 31 non-dialyzed and 7 peritoneally-dialyzed patients unless oral aluminium hydroxide was prescribed. Plasma aluminium levels were above normal in 26 patients on maintenance hemodialysis, but when aluminium hydroxide intake stopped there was a decrease in pre-dialysis plasma aluminium. Poor compliers (indicated by plasma phosphate levels) showed no change. Oral aluminium hydroxide can make a major contribution to plasma aluminium levels in patients with renal failure and should be treated with the same caution as high dialyzate aluminium. Post-dialysis plasma aluminium levels were always higher than pre-dialysis levels both on and off aluminium therapy despite the low dialyzate aluminium concentration. This rise may be due to tissue redistribution.

Administration, Oral↗
PubMed1980

Bone marrow cellularity and iron stores in chronic renal failure.

Bone marrow biopsies of 15 patients with chronic renal failure (CRF) were compared with those of a control group matched for age and sex. Using a point-counting method for assessing cellularity, there was no significant difference in marrow cellularity between the CRF patients and the control group. There was a significant difference in the myeloid-erythroid ratio (p < 0.05) between the control group and the CRF patients, the latter group having a lower ratio. A point-counting method was used for the assessment of iron stores. Of 8 CRF patients who had not been given intravenous iron, oral iron or blood transfusion, 2 had greater iron stores than the control group.

Adult↗