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Biomedical subjects

A T Webb

Publications and source records attributed to A T Webb.

13 recordsLinked to original sources
PubMed1997

The effect of change of renal replacement therapy on serum lipoprotein (a) concentration.

Lipoprotein (a) [Lp(a)] is an independent atherogenic risk factor. Lp(a) levels are elevated in patients on renal replacement therapy (RRT). This study looked at the effect of change of RRT on serum lipid and Lp(a) levels. Three groups were identified: (1) patients on dialysis who were transplanted; (2) those who had lost their transplants through immunorejection; (3) those who changed from continuous ambulatory peritoneal dialysis (CAPD) to hemodialysis (HD). All Lp(a) measurements were taken at least 3 months after the change of therapy. Our results were as follows: Group A (n = 21): 8 CAPD and 13 HD patients were transplanted. Median Lp(a) levels fell posttransplantation in the CAPD group (15.6 mg/dL vs 11.4 mg/dL, p = 0.04). The HD group showed a rise in cholesterol, low-density (LDL) and high-density lipoprotein (HDL) levels, with no change in Lp(a) levels. Group B (n = 11): 7 patients started CAPD and 4 HD. Overall, there was a marked increase in Lp(a) levels: median 38.2 mg/dL vs 55.9 mg/dL (p = 0.04), reflecting an increase in those starting CAPD (27.8 mg/dL vs 60.0 mg/dL, p = 0.01), with little change in the HD group (40.45 mg/dL vs 40.05 mg/dL). However, there was a decrease in cholesterol (7.4 mmol/L vs 5.1 mmol/L, p = 0.002) and LDL (5.5 mmol/L vs 3.3 mmol/L, p = 0.004). Group C (n = 16): 16 patients changed from CAPD to HD. Lp(a) levels were higher while on CAPD, as compared to when on HD (58.9 mg/dL vs 49 mg/dL, p = 0.03). Cholesterol (6.62 mmol/L vs 5.26 mmol/L, p = 0.006) and LDL (4.48 mmol/L vs 3.40 mmol/L, p = 0.004) were also higher when on CAPD. In conclusion, serum Lp(a) levels are clearly affected by the mode of the RRT, being highest in CAPD, and decline after transplantation or conversion to HD. Atherogenic risk is thus likely to differ between the modes of RRT and may be greatest for those on CAPD.

Adult↗
PubMed1995

Lipids and lipoprotein(a) as risk factors for vascular disease in patients on renal replacement therapy.

A large cohort of patients on renal replacement therapy were screened for the presence of symptomatic arterial disease affecting the coronary, cerebral or peripheral circulations. Ninety-two of 325 patients were found to have vascular disease. Those with vascular disease had significantly higher median lipoprotein(a) [Lp(a)] levels than those without (38.4 vs 14.2 mg/dl, P < 0.001), with a preponderance of Lp(a) levels greater than 30 mg/dl (58% vs 25% P < 0.001). Apolipoprotein(a) [apo(a)] isoform distribution was similar between the groups, but those with vascular disease had higher Lp(a) levels in the S2, S3/S4 and S4 isoform types. Comparison of 76 matched pairs of patients confirmed elevated Lp(a) levels in those with vascular disease. These patients also had significantly higher total cholesterol (6.66 vs 6.02 mmol/l) and low-density lipoprotein cholesterol (4.49 vs 3.86 mmol/l). Only Lp(a) was independently associated with vascular disease (P = 0.02). Elevated Lp(a) levels are significantly associated with the presence of vascular disease in patients on renal replacement therapy and may constitute another risk factor for the development of such disease in these patients.

Adult↗
PubMed1993

Does cyclosporin increase lipoprotein(a) concentrations in renal transplant recipients?

Cyclosporin, the immunosuppressant of choice for renal transplant recipients, has been implicated as the cause of abnormalities in serum lipid concentrations in these patients. We have measured serum lipoprotein(a) concentrations and analysed the distribution of apoprotein(a) isoforms in 90 renal transplant recipients receiving cyclosporin and prednisolone (with or without azathioprine), 59 patients receiving azathioprine and prednisolone alone, and 146 non-hyperlipidaemic controls. Cyclosporin-treated patients had significantly higher lipoprotein(a) concentrations (median 170 [interquartile range 55-382] mg/L) than those receiving azathioprine and prednisolone (64 [10-204] mg/L, p = 0.001) or the healthy controls (94 [18-280] mg/L, p = 0.008). The difference between the azathioprine and prednisolone group and the controls was not significant. Although the time since transplantation was significantly shorter for the cyclosporin-treated group, there was no correlation between lipoprotein(a) concentration and time since transplantation (r = -0.13, p = 0.18). Apoprotein(a) phenotyping showed no significant differences in the distribution of apoprotein(a) isoforms between the treatment groups or between patient and control groups. Lipoprotein(a) concentrations are higher in renal transplant recipients treated with cyclosporin than in those maintained on azathioprine and prednisolone. The mechanisms underlying this abnormality remain to be elucidated.

Adult↗
PubMed1993

Prevalence of intermittent claudication and risk factors for its development in patients on renal replacement therapy.

The prevalence of symptomatic intermittent claudication (IC) was assessed using a standard cardiovascular questionnaire in a cohort of 325 patients on renal replacement therapy (RRT). IC was found in 19% of patients, 77% of whom were smokers and 22% diabetic. It was more common in men than women and in smokers than non-smokers (p < 0.001). Those with IC were significantly older (61 years vs. 50 years p < 0.001), smoked more (23 pack years vs. 12 pack years p = 0.002), had higher median systolic blood pressures (143 mmHg vs. 140 mmHg p = 0.041) and median triglyceride levels (2.07 mmol/l vs. 1.60 mmol/l p = 0.023) than those renal patients without IC. A case control study matching for age, sex and treatment revealed patients with IC to have higher median systolic blood pressure (147 mmHg vs. 140 mmHg p = 0.031), cholesterol (6.70 mmol/l vs. 5.90 mmol/l p = 0.029), LDL cholesterol (4.64 mmol/l vs. 3.86 mmol/l p = 0.011), and contained a greater proportion of smokers (78% vs. 50% p < 0.001). IC is common in patients on RRT. Whilst smoking was prevalent among those with IC it was much less frequent than in the general population with IC. Other factors such as hypertension, lipid abnormalities or the uraemic state itself may also be important in the development of IC in these patients.

Adult↗
PubMed1993

Lipoprotein (a) in patients on maintenance haemodialysis and continuous ambulatory peritoneal dialysis.

Lipoprotein (a) concentrations and apoprotein (a) isoforms were measured in 99 haemodialysis and 79 peritoneal dialysis patients and compared with a normal population. Peritoneal dialysis patients demonstrated a threefold and haemodialysis a twofold increase in median Lp(a) values compared to controls (P < or = 0.001). The peritoneal dialysis group had significantly more patients with Lp(a) values greater than 30 mg/dl compared to controls, (53% versus 22% P < or = 0.001). In addition both patient groups demonstrated significant hypertriglyceridaemia (P < or = 0.001), reduction in HDL (P < or = 0.001) and elevation of the cholesterol/HDL ratio (P < or = 0.001) compared with controls. Peritoneal dialysis patients also demonstrated significant hypercholesterolaemia (P < or = 0.003). Lipoprotein (a) concentrations are considerably elevated in patients on maintenance dialysis and this occurs in addition to the typical lipoprotein disturbances. This elevation may increase vascular risk, particularly in the peritoneal dialysis group who also have hypercholesterolaemia and reduced HDL.

Arteriosclerosis↗
PubMed1993

Prevalence of symptomatic arterial disease and risk factors for its development in patients on continuous ambulatory peritoneal dialysis.

The prevalence of coronary, cerebral, and peripheral arterial disease was assessed using a standard cardiovascular questionnaire in a cohort of 70 patients on continuous ambulatory peritoneal dialysis (CAPD). Symptomatic vascular disease was found in 47% of patients, 72% of whom were smokers and 30% diabetic. In 39% of these patients vascular disease was evident prior to the commencement of peritoneal dialysis. A case control study matching for age and sex revealed patients with vascular disease to have higher median systolic blood pressure (162 mmHg vs 150 mmHg, p = 0.026), cholesterol (6.60 mmol/L vs 6.00 mmol/L, p = 0.014), and LDL cholesterol (4.80 mmol/L vs 3.80 mmol/L, p = 0.009). Vascular disease is common in patients on peritoneal dialysis, a considerable proportion of whom have the disease prior to the commencement of dialysis. Elevated systolic blood pressure and hypercholesterolemia, but not smoking, are most closely associated with vascular disease in these patients.

Adult↗
PubMed1992

Lipid and lipoprotein (a) concentrations in renal transplant patients.

Lipid and lipoprotein concentrations, including lipoprotein (a), were measured in 67 clinically stable renal allograft recipients and compared with age- and sex-matched controls. Median lipoprotein (a) concentrations were significantly elevated in the transplant group (P = 0.048), with the distribution of apoprotein (a) isoforms being similar between the two groups. The transplant group also demonstrated significant elevations in cholesterol (P less than 0.0001), triglycerides (P = 0.0007) and low-density lipoprotein cholesterol (P less than 0.0001). There was no significant difference in high-density lipoprotein cholesterol concentrations between the groups although there was the expected tendency for higher values in females. Lipoprotein abnormalities are common following renal transplantation and these patients also demonstrate elevated lipoprotein (a) values. This unique lipoprotein is known to be atherogenic and may contribute to the development of vascular disease, which is a common mode of death in these patients.

Adolescent↗
PubMed1975

Quantitative urine culture by reagent strip incubation.

The filter paper culture-tetrazolium test ressults have been compared with routine hospital streak plate cultures in 400 random urine specimens. Pseudomonas cultures tended to impart a color change to the test pads which rendered interpretation difficult. While a consistently accurate quantitative interpretation of these cultures did emerge during the course of the trial studies, some degree of observer accommodation and bias, in terms of the manufacturer's instructions and description, was necessary to achieve an appropriate reading. When the hospital laboratory results and culture strip test results are compared in terms of colony counts greater than 10-4 bacteria per milliliter and less than 10-4 bacteria per milliliter, the method was found to be 93% sensitive for the total count and 83% sensitive for the gram-negative count with a specificity correlation of 96% for the total and gram-negative counts, respectively.

Bacteria↗