PubMed Health⌕ Search

Biomedical subjects

M Venning

Publications and source records attributed to M Venning.

At least 19 recordsLinked to original sources
PubMed2003

End-stage renal disease in Indo-Asians in the North-West of England.

BACKGROUND: The incidence of end-stage renal disease (ESRD) in England is increasing. There is a higher incidence of ESRD in British Indo-Asians than in the White population. AIM: To determine to what degree the increasing demand for renal replacement therapy in the UK is due to Indo-Asian patients. To study the presentation to renal services of Indo-Asian patients with ESRD and report any inequalities in initial treatment of Indo-Asian patients with ESRD compared to their White counterparts. DESIGN: Prospective, inception cohort study. METHODS: Consecutive adult patients with ESRD who started renal replacement therapy between 1 April 2000 and 31 December 2001 in all 14 renal units serving an area from North Cheshire to South Cumbria, including Greater Manchester and Lancashire, were recruited and interviewed. RESULTS: Of the 578 patients, 9.5% were Indo-Asian. The annual acceptance rate for renal replacement therapy was 342 per million population in Indo-Asians, compared with 91 per million population in the White population ( p < 0.001). Indo-Asian patients with ESRD were younger (median age 51 years vs. 60 yrs, p = 0.006) and more socially deprived (81% vs. 36.5% in the 5th Carstairs quintile, p < 0.001). A greater proportion of Indo-Asian patients with ESRD presented late to specialist renal services (31% vs. 19%, p = 0.03). Once adjusting for their younger age, atherosclerotic renovascular disease and/or hypertensive nephropathy was more prevalent in Indo-Asian patients (OR 4.9; p = 0.03). There was no difference in the initial mode of maintenance dialysis or the perception of choice the patients felt they had, based on their ethnicity. DISCUSSION: There is a silent epidemic of ESRD in Indo-Asian patients in the North-West, possibly vascular in aetiology, in which specialist intervention is late. This suggests that Indo-Asian patients should be prioritized for early intervention strategies to reduce the burden of ESRD.

Age Distribution↗
PubMed2001

Resistance to macrocyclic lactone anthelmintics by Haemonchus contortus and Ostertagia circumcincta in sheep in New Zealand.

AIM: To establish the efficacy of oral formulations of ivermectin and moxidectin against naturally acquired abomasal nematode infections on a North Island sheep farm. METHODS: Two controlled slaughter trials were undertaken. In the first, 30 sheep on pasture were randomly allocated on the basis of faecal egg count to 1 of 3 groups, comprising an untreated control group and 2 treatment groups. One treatment group was given a single oral dose of ivermectin and the other a single oral dose of moxidectin, both at the manufacturer's recommended dose rates of 0.2 mg/kg liveweight. Six days after treatment, all animals were slaughtered and their abomasa recovered for worm counting. The second trial, which involved 47 animals, was essentially the same as the first except that, as well as involving the slaughter of 30 sheep from all 3 groups, 6 days after treatment, it also included a further 8 untreated control animals and 9 moxidectin treated animals which were slaughtered 27 days after treatment. RESULTS: At 6 days after treatment, moxidectin was highly effective against all 3 of the abomasal nematodes present. While ivermectin was similarly effective against Trichostrongylus axei 6 days after treatment, it was not effective against either Ostertagia circumcinta or Haemonchus contortus, against which average efficacies of only 63.6% and 61.6%, respectively, were recorded. At 27 days after treatment, moxidectin, was also highly effective against T. axei (97.3% reduction) but not against either H. contortus (71.4% reduction) or O. circumcinta (61.0% reduction). CONCLUSIONS: These results provide the first record of macrocyclic lactone resistance in H. contortus in sheep or in any other host in New Zealand, and the first case where such resistance has been exhibited in more than one parasite species at a time. Although the therapeutic efficacy of moxidectin was high against these resistant H. contortus and O. circumcincta strains, resistance to moxidectin was indicated by its diminished prophylactic activity against them. It is suggested that this reduction in the prophylactic activity of moxidectin is also likely to reduce its apparent current high therapeutic efficacy. CLINICAL RELEVANCE: As well as providing further evidence that it can no longer be automatically assumed that macrocylic lactone anthelmintics will be effective on sheep farms in this country, these findings also present a warning that increasingly complex parasite control options may have to be faced in the future.

Journal Article↗
PubMed2001

The effect of different methods of storage on the results of serum total CO2 assays.

Metabolic acidosis frequently complicates end-stage renal failure. In haemodialysis patients its severity is usually monitored by measurement of the total CO(2) (TCO(2)) level. Samples from 'satellite dialysis' patients are often stored prior to analysis. We investigated the affect of storage of 21 samples for 24 h under different conditions prior to analysis. If samples were stored at room temperature the TCO(2) fell from 22.7+/-4.2 mmol/l to 21.6+/-3.7 mmol/l (P=0.001). If the same samples were spun and stored at 4 degrees C the TCO(2) was 22.4+/-3.9 mmol/l (P=not significant). We conclude that the magnitude in the fall of TCO(2) stored at room temperature for 24 h is unlikely to be clinically significant and can be prevented by spinning the sample and refrigerating it.

Acidosis↗
PubMed1997

Interstitial myofibroblasts: predictors of progression in membranous nephropathy.

AIMS: To determine the role of interstitial myofibroblasts in the progression of membranous nephropathy; and to assess the predictive value of quantifying myofibroblasts in determining long term renal outcome. METHODS: All cases of membranous nephropathy, diagnosed by renal biopsy at University Hospital of South Manchester between 1984 and 1987, were studied retrospectively. The biopsy specimens (n = 26) were reviewed and analysed morphometrically to measure interstitial volume as a proportion of the total volume of renal cortex, and numbers of interstitial myofibroblasts (cells positive for alpha-smooth muscle actin within the interstitium). Clinical data, with a follow up of seven to eight years, was available for 24 patients, and renal outcome was correlated with pathological changes in the initial diagnostic biopsy specimen. RESULTS: The number of myofibroblasts and interstitial volume were inversely correlated with creatinine clearance at the initial biopsy, and at the end of follow up. Percentage sclerosed glomeruli or stage of glomerular disease, assessed by electron microscopy, did not correlate with renal function at initial biopsy or during follow up. The number of myofibroblasts, but not interstitial volume, correlated with severity of proteinuria at initial biopsy. Of 15 biopsy specimens showing no or mild interstitial fibrosis, four showed a notable increase in the number of interstitial myofibroblasts. All of these patients developed chronic renal failure, compared with three of 11 patients whose specimens showed no or a mild increase in myofibroblast numbers. CONCLUSIONS: Interstitial myofibroblasts play a role in the development of interstitial fibrosis and progressive renal failure in membranous nephropathy. Increased numbers of myofibroblasts in biopsy specimens showing only mild fibrosis may predict subsequent chronic renal failure.

Actins↗
PubMed1997

Impact of increasing dialysis volume on adequacy targets: a prospective study.

Failure to achieve target values for both urea (Kt/V) and creatinine clearance has been associated with increased morbidity and mortality in continuous ambulatory peritoneal dialysis patients. The conventional continuous ambulatory peritoneal dialysis regimen, which uses four 2-L exchanges per day, has resulted in up to 40% of such patients failing to achieve proposed targets for weekly Kt/V of 1.7 and weekly creatinine clearance (WCC) of 50 L. In a prospective study, the impact of increasing prescribed volumes by 0.5 L per exchange was evaluated on attaining urea and creatinine clearance targets over a 1-yr period. At 1 yr, 17 patients remaining on the increased dialysis prescription were compared with 18 patients remaining on an unchanged regimen. The mean increase in daily prescribed volume was 1.5 L (22%). This resulted in a significant increase in both peritoneal dialysis Kt/V (1.59 to 1.78 L = 12%) and peritoneal dialysis WCC (45.8 to 50.1 L = 10%) by 1 yr. Because of loss of renal function, there was no significant increase in total clearance at 1 yr, but this loss of renal clearance was offset by the gain in peritoneal clearance. Residual renal function fell at a similar rate in both the increased dialysis and control groups. In the latter, although peritoneal clearance remained stable over the 1-yr period, loss of renal function resulted in reductions in both total Kt/V and WCC. In conclusion, exchange volume can be increased to compensate for loss of renal function over a 1-yr period. Progressive loss of renal clearance resulted in only a modest gain in total solute clearance. It was the larger patients who tolerated the increase in exchange volumes. However, such patients (by virtue of their size) tended not to achieve target values for solute clearance, and the modest gain in peritoneal clearance was insufficient to increase the number of patients in this group achieving such targets for dialysis adequacy.

Adult↗
PubMed1996

The influence of small solute clearance on dietary protein intake in continuous ambulatory peritoneal dialysis patients: a methodologic analysis based on cross-sectional and prospective studies.

The statistical relationship between solute clearance (expressed as Kt/V) and dietary protein intake (DPI; estimated from the normalized protein catabolic rate [NPCR]) has led to the assumption that dialysis dose is one of the most important determinants of DPI in continuous ambulatory peritoneal dialysis patients. However, there is increasing concern about the clinical value of such a correlation between variables that contain common components. We have investigated the statistical nature of the cross-sectional correlation between Kt/V and NPCR using mathematical modelling. In addition, in a prospective study, the impact of increasing Kt/V on protein intake estimated from the NPCR and from 3-day food diaries (DPI) was evaluated in 59 patients over a 1-year period. Two thousand sets of random numbers were generated for the components, from which Kt/V and NPCR were calculated. The subsequent cross-sectional correlation between the randomly generated Kt/V and NPCR was highly significant (r = 0.64 to 0.74). In contrast, there was a much weaker cross-sectional correlation between relatively independent measures of dialysis dose (urea clearance) and protein intake measured from food diaries (r = 0.36). Analysis of the prospective relationship revealed a significant correlation with a decrease in urea clearance (due to loss of renal function) accompanied by a decrease in both PCR (r = -0.80) and DPI (r = -0.51). In contrast, when Kt/V was increased (by larger volume exchanges) there was no significant increase in protein intake. This study has demonstrated that the strength of the cross-sectional relationship between Kt/V and NPCR is due to mathematical coupling of "like with like," and this correlation cannot be used to substantiate a link between dialysis dose and nutrition. Prospective analysis does show a dependence of protein intake on urea clearance. However, this dependence is only seen in those patients undergoing a reduction in clearance due to loss of renal function. Increasing exchange volume to offset such losses was not accompanied by improvements in protein intake.

Adult↗
PubMed1995

Energy metabolism during CAPD: a controlled study.

Abnormalities of energy metabolism may exacerbate the high prevalence of protein-calorie malnutrition and inadequate calorie intake in continuous ambulatory peritoneal dialysis (CAPD) patients, leading to further nutritional depletion. In a controlled study, using indirect calorimetry, we evaluated oxygen consumption (VO2), CO2 production, resting energy expenditure, and respiratory exchange ratio (RER) in 12 CAPD patients at rest and during a standard CAPD exchange and in 11 healthy nonuremic control patients. In addition, we investigated the influence of nutritional status and dialysis adequacy on energy metabolism in the CAPD group. There was no significant difference in resting energy parameters between the two groups. Unlike the control group, blood glucose and RER were maintained during prolonged fasting in the CAPD patients. This observation indicates that all the absorbed glucose was used as a metabolic fuel preventing fat oxidation. There was no significant relationship between energy expenditure and dialysis adequacy. There was no significant relationship between nutritional state (including energy intake) and energy expenditure despite evidence of malnutrition in 41% of the patients. If maintenance of "normal levels" of energy expenditure occurs in dialysis patients with suboptimal calorie intake (especially with evidence of protein-calorie malnutrition), this inability to conserve energy may act as an additional risk factor for ongoing malnutrition.

Aged↗
PubMed1994

An evaluation of a controlled release system for selenium in lambs.

The efficacy of 100-day controlled release anthelmintic capsules containing Se for increasing and maintaining the Se status of lambs was evaluated. Capsules containing either 7.7 or 13.9 mg of Se increased the mean blood Se concentrations from 1.50 +/- 8.4 nmol/l in the unsupplemented lambs to 440 +/- 29.8 and 990 +/- 83.4 nmol/l respectively 100 days after their administration. Blood Se concentrations then declined to 250 +/- 21.5 and 380 +/- 50.1 nmol/l respectively by day 210. The addition of 13.9 mg of Se to a 100-day controlled release anthelmintic capsule is an effective method of protecting lambs from Se deficiency for at least 180 days.

Journal Article↗
PubMed1994

Computed tomographic peritoneography: CT manifestations in the investigation of leaks and abnormal collections in patients on CAPD.

Continuous ambulatory peritoneal dialysis (CAPD) is now a common form of treatment for patients with chronic renal failure. However, peritoneal leaks and abnormal intraperitoneal collections can be problematic in these patients, leading to poor dialysate returns, anterior abdominal wall oedema, and genital oedema. We report on a series of 62 computed tomographic peritoneograms performed using a standard protocol on 39 symptomatic patients over 6 years. Thirty-seven scans identified peritoneal leaks or abnormal collections, including leaks from the present dialysis catheter site and previous catheter sites, and collections in inguinal and abdominal herniae. Three patients had abnormalities at two sites each. Localization of leaks and collections is of direct use when surgical management of these patients is contemplated and this paper aims to illustrate the typical CT findings occurring in these patients.

Abdominal Muscles↗
PubMed1993

Limitations of kinetic models as predictors of nutritional and dialysis adequacy in continuous ambulatory peritoneal dialysis patients.

Nutrition has been shown to predict clinical outcome in continuous ambulatory peritoneal dialysis (CAPD) patients. However, despite the positive relationship between KT/V (urea) and the normalised protein catabolic rate, the ability of urea kinetic modelling to predict clinical outcome or nutrition remains inconclusive. We have evaluated the relationship between nutrition and achieved dialysis in a cross-sectional study of 147 stable CAPD patients on dialysis for a mean period of 22 months. Protein-energy malnutrition was present in 22-32% of the study population. 39 and 41% of the population failed to achieve suggested adequacy targets of 50 liters/week for total creatinine clearance and a weekly KT/V (urea) of 1.7, respectively. Severely malnourished patients had significantly greater normalised clearance and adequacy values than well-nourished patients. Intrinsic actual peritoneal clearance bore no relation to patient size. The subsequent normalisation of this value by a component of patient mass results in a mathematical bias against well-nourished or obese patients. This may explain the failure of such adequacy values to reflect outcome and argues against accepting such values as measures of dialysis well-being.

Body Weight↗
PubMed1992

Association of Wegener's granulomatosis with HLA antigens and other genetic markers.

The frequencies of the HLA-A, B, C, DR, DQ antigens and of several other genetic markers in biopsy proved and well characterised patients with Wegener's granulomatosis were compared with control frequencies of the region. A highly significant increase in HLA-DR1 was found. The percentage combined frequency of DR1-DQw1 was significantly higher in patients than in the controls. Interestingly, association with the red cell enzyme GLOI and complement locus C4B was also seen. As both of these markers are either linked or within the major histocompatibility complex region (MHC) this is further evidence for the involvement of chromosome 6 in the pathogenesis of Wegener's granulomatosis. To understand the pathology of the disease fully molecular genetic studies of the MHC region are warranted.

Adult↗