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Biomedical subjects

S Fenton

Publications and source records attributed to S Fenton.

At least 55 records · Page 3Linked to original sources
PubMed1995

Renal replacement therapy in Canada: a report from the Canadian Organ Replacement Register.

We report here the demography and results of renal replacement therapy in Canada from 1981 to 1992. The new case rate for patients entering renal replacement therapy programs in Canada has increased dramatically over the last 12 years, from 49.9 per million to 98.4 per million of the population. The largest increases have been among the elderly, from 146.2 per million in 1981 to 381.9 per million in 1992 for those aged 65 to 74 years. There has been an even more dramatic increase for those over 75 years, from 83.6 per million in 1981 to 261.6 per million in 1992. There has been a similar increase in the prevalence rate, with an increase from 229.1 per million in 1981 to 518.5 per million in 1992. The hemodialysis rate for 1992 was 172.2 per million and that for peritoneal dialysis was 103.1 per million of the population. The renal transplantation rate also increased from 20 per million in 1981 to 34.8 per million in 1988, but unfortunately has decreased to 27.5 per million in 1992. Diabetes is now the most common primary renal diagnosis, having increased from 15% in 1981 to 24% in 1992. The 5-year survival rate of all patients on renal replacement therapy was 55%. For nondiabetic patients, the 5-year survival rate ranged from 85% for the those aged 15 to 44 years to 20% for those over 65 years. Among diabetic patients, the 5-year survival rate declined from 58% for the 15 to 44 year age group to 10% for those over 65 years.

Adolescent↗
PubMed1995

Trans fatty acids in the Scottish diet. An assessment using a semi-quantitative food-frequency questionnaire.

Trans fatty acids produced during hardening of oils have been associated with higher cholesterol levels and increased risk of heart disease. The potential risk from trans fatty acids may be greater in populations with relatively low intakes of essential fatty acids such as the Scots, who also have a high prevalence of heart disease. Means and ranges of trans fatty acid intakes are reported here for a Scottish population. A semi-quantitative food-frequency questionnaire was used to survey the diet of 10,359 Scottish men and women aged 40-59 years in 1984-6 as part of the baseline Scottish Heart Health Study. Trans fatty acid levels were calculated for each food item on the questionnaire and the total subdivided into that which is derived naturally (primarily by bacterial fermentation in ruminants) and that which is produced during industrial hydrogenation (hardening) of vegetable and fish oils. Means and ranges of intakes of each trans fatty acid variable were calculated by sex, age, smoking and social class groups. Mean total trans fatty acid intakes for men were 7.1 (SD 3.1) g/d, 2.7 (SD 2.9)% energy and for women were 6.4 (SD 2.9) g/d, 3.3 (SD 3.0)% energy. Industrially hydrogenated trans fatty acids made up nearly 58% of the total intake for men and 61% for women, with about 60% coming from cakes, biscuits and sweets, and 20% coming from the cheaper hard margarines. The main sources of the naturally derived trans fatty acids were red meat (27%), milk (20%), butter (18-19%) and cheese (13-16%). Differences between age, smoking and social class groups were apparent. However, apart from the social class differences of up to 1 g/d, these were so small that they are unlikely to be of any biological significance unless compounded by other factors such as marginal essential fatty acid adequacy. The possibility of trans fatty acid intakes up to 48 g/d and 12% total energy (compared with the Department of Health (1991) recommendations of 5 g/d or 2% energy) highlights the need for careful monitoring of the health risks at these high levels of intake.

Adult↗
PubMed1995

Strategies for sampling black and ethnic minority populations.

BACKGROUND: The objective of the study was to describe the design and sampling methods used to carry out face-to-face interviews with a sample of the black and ethnic minority population of the area. This study was conducted in the city of Bristol, England (part of Bristol and District Health Authority). METHODS: The sample was based on up to 1000 interviews with black Caribbean/African, South Asian and Far-East Asian residents. The design of the study focuses on the problems of definition of the appropriate group to sample and the various sampling techniques that were necessary to procure the interviews. RESULTS: A total of 574 interviews were carried out by bilingual interviewers matched for sex and ethnicity of the respondent, thereby allowing analysis that would be beneficial to the Health Authority in its planning and decision-making. CONCLUSIONS: The use of name spotting and 'snowball' sampling proved the most productive. The Electoral Register was preferred to the Family Health Services Authority lists. Interviewers must be carefully selected and adequately trained to work in this difficult area. The questionnaire must be culturally and linguistically acceptable across all the ethnic groups.

Africa↗
PubMed1995

An analysis of predictors of long-term cadaveric renal allograft survival.

To determine factors predictive of long-term graft function in patients treated prophylactically with an antilymphocyte antibody, 670 first cadaveric adult renal transplant procedures performed between 1985 and 1991 were reviewed. The actuarial 1- and 5-year patient survival in this group was 95% and 87% respectively, and graft survival was 84% and 70% respectively. The final analysis was based on a study group of 635 patients which excluded 28 patients who lost grafts to early technical failures and 8 patients who were not induced with an antilymphocyte preparation. Multivariate analysis showed that 5-year graft survival was lower in patients with delayed graft function (p = 0.0001), in those who had an acute rejection episode in the first 6 months post-transplant (p = 0.0001), recipients greater than 55 years of age at the time of transplant (p = 0.0001), in patients who were highly sensitized at the time of transplant (p = 0.0331) and, finally, in those who received a graft from an older donor (p = 0.044). The 209 patients with delayed graft function had a 16% lower long-term graft survival than 425 patients with early graft function (62% vs. 78% respectively at 5 years). One or more rejection episodes in the first 6 months post-transplant (329 patients) reduced long-term graft survival by 13% compared to those who did not have a rejection episode (67% vs. 80% respectively at 5 years).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1993

Renal osteodystrophy in diabetic patients.

To assess the effects of diabetes mellitus on renal osteodystrophy, we examined the database of 256 patients (45% on hemodialysis and 55% on peritoneal dialysis) who were prospectively studied in three Toronto dialysis centers between October of 1987 and 1989. All patients had serial documentation of their clinical, laboratory and risk parameters of bone disease, and completed a series of investigations that included the deferoxamine test, measurement of intact 1-84 PTH levels, and an iliac crest bone biopsy. Twenty-five percent of these patients were diabetic. When compared to non-diabetic patients, they were on dialysis for a shorter duration (2.4 +/- 0.3 vs. 4.7 +/- 0.3 years; P < 0.0002), used calcium carbonate as the only phosphate binder more frequently (40 vs. 25%; P < 0.007), and had lower parathyroid hormone levels (12 +/- 1.4 vs. 24 +/- 2.3 pmol/liter; P < 0.002). High-turnover bone disorders (that is, osteitis fibrosa and mixed disorder) were distinctly uncommon (8 vs. 33%; P < 0.01 by Fisher's exact test), while the mild (19 vs. 9%; P = NS) and the aplastic disorders (with mean stainable bone surface aluminum of 6.5 +/- 0.7%) (46 vs. 31%; P = NS) tended to be more common in diabetic patients. The prevalence of aluminum bone disease was the same in both groups (27%). Diabetic patients ingested a smaller cumulative dose of aluminum gels (3.7 +/- 0.6 vs. 9.3 +/- 1.1 kg; P < 0.005), yet had a higher rate of aluminium accumulation on bone surfaces than non-diabetic patients (1.5 +/- 0.19 vs. 0.96 +/- 0.10% per month on dialysis; P < 0.015).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Aplastic osteodystrophy without aluminum: the role of "suppressed" parathyroid function.

We evaluated 259 dialysis patients using serum parathyroid hormone (PTH, IRMA; normal range 1 to 5.5 pM or 10 to 55 pg/ml), the deferoxamine infusion test and iliac crest bone biopsy to determine the various forms of renal osteodystrophy and their risk factors. Although half of the biopsied patients had low turnover osteodystrophy, evidence of aluminum toxicity was present in only 1/3 of them. Additional risk factors for this bone lesion included treatment with peritoneal dialysis, ingestion of calcium carbonate, diabetes mellitus and advanced age. The PTH levels in patients with the aplastic lesion were significantly lower than in patients with normal or high bone turnover lesions [7.7 +/- 6.1 vs. 36.9 +/- 3.2 pM (77 +/- 61 vs. 369 +/- 32 pg/ml), P < 0.0001]. Aside from hypercalcemia, these patients were relatively asymptomatic. In a second study, 10 patients on peritoneal dialysis with the aplastic lesion had their dialysate calcium lowered from 1.62 to 1.0 mM. This resulted in a significant increase in PTH levels, from [3.7 +/- 0.8 to 10.6 +/- 1.9 pM (37 +/- 8 to 106 +/- 19 pg/ml), P < 0.001] which persisted over the nine-month observation period. In conclusion, the aplastic lesion is the most common form of renal osteodystrophy, with aluminum intoxication implicated in only 1/3 of the cases. In the remainder, factors identified include therapy with peritoneal dialysis using supraphysiological dialysate calcium, oral CaCO3 intake and diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1992

Non-invasive prediction of aluminum bone disease in hemo- and peritoneal dialysis patients.

Between October 1987 and October of 1989, we conducted a prospective study to evaluate non-invasive test strategies for predicting aluminum bone disease (ABD) in a group of largely unselected dialysis patients based on their deferoxamine (DFO) test alone, or the combined results of their DFO test and intact 1-84 parathyroid hormone (PTH) levels. These test parameters were evaluated against the pathological diagnosis of ABD based on bone biopsy ("gold standard"). A total of 445 patients in three dialysis centers in Toronto were serially followed for their clinical, laboratory and risk parameters for renal osteodystrophy during the study, and 259 (142 PD and 117 HD) patients underwent a series of investigations which included the DFO test, measurement of intact 1-84 PTH levels, and an iliac crest bone biopsy. Serum aluminum ([Al]) level greater than or equal to 3700 nM (or 100 micrograms/liter) had a positive predictive value (PPV) of 75% for ABD in our PD and 88% in our HD patients, but its sensitivity was low (10 and 37%). Delta [Al] (that is, incremental rise of serum [Al] from baseline post-DFO) was useful in predicting ABD in our PD but not HD patients. Test combination based on delta [Al] greater than or equal to 5550 nM (or 150 microgram/liter) and PTH levels less than 20 pM (or 200 pg/ml) yielded the best PPV greater than or equal to 95% for ABD in both PD and HD patients. This test cut-off would remain highly predictive of ABD even if the prevalence of ABD decreases to as low as 5% for the PD patients and 10% for the HD patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1983

Bone disease after jejuno-ileal bypass for morbid obesity.

Fifteen patients who had undergone a 14 inches X 4 inches jejuno-ileal bypass operation for obesity, 3 to 4 years earlier, were investigated by iliac bone biopsy, radiology and routine biochemistry, including 25-hydroxy-vitamin D and parathyroid hormone estimations. Two patients had histological osteomalacia which was mild in one. A further 9 patients had abnormal bone biopsies, there being an excess of trabecular bone surface covered by osteoid with a normal or reduced amount of calcification front. Six of these 9 showed an increase in trabecular resorption, although in none were there excessive numbers of osteoclasts. The likely explanation for these findings is that these 9 patients had early osteomalacia with mild hyperparathyroidism, making a total of 11 patients out of 15 with osteomalacia. Radiology and blood chemistry were poor predictors of histological bone disease.

Adult↗
PubMed1983

Evidence that the hypothalamus may be a source of a circulating Na+-K+-ATPase inhibitor.

Acetone extracts from a variety of rat tissues were tested for their ability to stimulate renal glucose-6-phosphate dehydrogenase (G6PD) activity at 2 min in an in-vitro cytochemical assay which is a marker of the sodium potassium-dependent adenosine triphosphatase (Na+-K+-ATPase) inhibiting activity. Extracts of the hypothalamus were the only ones found to be active in this system. Acetone extract of hypothalamus also inhibited renal Na+-K+-ATPase activity in vitro. The G6PD-stimulating activity from one hypothalamus was about 10000 to 100000 times greater than that of 1 ml plasma. The G6PD-stimulating activity of hypothalamic extracts from rats which had been on a high sodium intake for 4 weeks were approximately 150 times more active than those obtained from rats which had been on a low sodium diet. The G6PD-stimulating activity of the corresponding plasma was sixfold more active. These findings suggest that a circulating sodium transport inhibitor(s) may be secreted from the hypothalamus.

Animals↗
PubMed1981

Evidence for a raised concentration of a circulating sodium transport inhibitor in essential hypertension.

A cytochemical technique that measures the ability of plasma to stimulate guinea-pig renal glucose-6-phosphate dehydrogenase (G6PD) activity in vitro, which is a marker of its ability to inhibit Na+-K+-adenosine-triphosphatase (Na+-K+-ATPase), was used in 19 patients with essential hypertension and 23 normotensive, healthy subjects. The ability of plasma to stimulate G6PD was significantly greater in the hypertensive patients when they were taking their normal sodium diet than in the normotensive subjects, and was significantly correlated with blood pressure. The ability of plasma to stimulate G6PD was inversely correlated with plasma renin activity in the hypertensive patients and increased with age and sodium intake in the normotensive subjects. These results support the hypothesis that essential hypertension, and also perhaps the increase in blood pressure with age in communities that consume large quantities of salt, is in part due to an increase in a circulating concentration of an inhibitor of Na+-N+-ATPase.

Adult↗
PubMed1981

An increase in a circulating inhibitor of Na+,K+-dependent ATPase: a possible link between salt intake and the development of essential hypertension.

1. The plasma's ability to stimulate guinea-pig renal glucose 6-phosphate dehydrogenase (G6PD) in vitro was measured by a cytochemical technique in 23 normotensive subjects and 19 patients with hypertension, all of whom were studied on their normal sodium intake. The ability of plasma to stimulate renal G6PD was significantly (P less than 0.001) increased in the hypertensive patients (mean 195 +/- 52 units/ml) compared with the normotensive subjects (mean 22.2 +/- 5.8 units/ml). In all 42 individuals, there was a significant correlation between diastolic pressure and the ability of plasma to stimulate G6PD (r = 0.69 P less than 0.001). 2. The ability of plasma to stimulate G6PD was greatest in the hypertensive patients with values of plasma renin activity below the normal range. In the normotensive subjects the ability of plasma to stimulate G6PD was significantly greater in the older subjects. 3. As the ability of plasma to stimulate G6PD reflects its ability to inhibit Na+,K+-dependent ATPase, these results suggest that patients with essential hypertension have an increase in a circulating inhibitor of Na+,K+-ATPase. The results support the hypothesis that a rise in a circulating sodium transport inhibitor may, in part, be responsible for the rise in blood pressure in essential hypertension, and may form the link between salt intake, abnormalities of sodium transport and a rise in blood pressure.

Adult↗
PubMed1981

Stopping life-sustaining medical treatment: psychiatric considerations in the termination of renal dialysis.

Data are presented regarding the decision by medical staff and by patients to discontinue renal dialysis. Some relevant issues regarding the patients are discussed, including their mental competence, underlying motivation and psychiatric state. Also some of the medical factors involved in the decision to stop treatment are considered. Emphasis is placed on the importance of the patients's sense of active participation and involvement in his treatment. Mention is made of the importance of interventions to decrease the psychological morbidity in survivors of patients who stop dialysis.

Anxiety↗