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Biomedical subjects

P F Naish

Publications and source records attributed to P F Naish.

At least 19 recordsLinked to original sources
PubMed2004

Nutritional status, functional capacity and exercise rehabilitation in end-stage renal disease.

A significant percentage of patients with end-stage renal disease are malnourished and/or muscle wasted. Uremia is associated with decreased protein synthesis and increased protein degradation. Fortunately, nutritional status has been shown to be a modifiable risk factor in the dialysis population. It has long been proposed that exercise could positively alter the protein synthesis-degradation balance. Resistance training had been considered as the only form of exercise likely to induce anabolism in renal failure patients. However, a small, but growing, body of evidence indicates that for some dialysis patients, favourable improvements in muscle atrophy and fibre hypertrophy can be achieved via predominantly aerobic exercise training. Moreover, some studies tentatively suggest that nutritional status, as measured by SGA, can also be modestly improved by modes and patterns of exercise training that have been shown to also increase muscle fibre cross-sectional area and improve functional capacity. Functional capacity tests can augment the information content of basic nutritional status assessments of dialysis patients and as such are recommended for routine inclusion as a feature of all nutritional status assessments.

Exercise↗
PubMed2002

Reliability of indices of neuromuscular leg performance in end-stage renal failure.

The purpose of this study was to examine the day-to-day reproducibility and single measurement reliability of peak force, time to half peak force and rate of force development indices of knee extension neuromuscular performance in patients with end-stage renal failure. Eleven self-selected patients (6 men, 5 women) receiving maintenance dialysis (dialysis history 67 +/- 42.8 month) completed 3 inter-day assessment sessions. Each comprised a standardized warm-up and 3 intermittent static maximal voluntary actions of the knee extensors of the preferred limb (45 degrees knee flexion angle [0 degrees = full knee extension]) using a specially-constructed dynamometer. Repeated measures ANOVA of coefficient of variation scores revealed significant differences between indices in their reproducibility across day-to-day trials. Post-hoc comparisons of group mean scores suggested that peak force (6.6 +/- 3.0%) offers significantly greater measurement reproducibility than time to half peak force (16.8 +/- 9.5%) or rate of force development (20.3 +/- 12.1%). Intraclass correlation coefficients and standard error of measurement scores showed that single-trial assessments of peak force, time to half peak force and rate of force development would demonstrate limited precision and capability to discriminate subtle intra-subject or inter-subject changes in neuromuscular performance.

Adult↗
PubMed2002

Low-volume exercise rehabilitation improves functional capacity and self-reported functional status of dialysis patients.

OBJECTIVE: The purpose of this study was to examine the effects of a program of low-volume exercise rehabilitation on the functional capacity and self-reported functional status of nonanemic dialysis patients. DESIGN: This was a controlled study in a clinical setting with a repeated measures design. Functional capacity and functional status were assessed before and after 12 wk of exercise rehabilitation or 12 wk of normal activity for two groups of dialysis patients. RESULTS: Mixed-model repeated measures analysis of variance revealed significant group by time interactions characterized by improvements for the exercise rehabilitation group alone in total walk, stair-climb, and stair-descent times of 15+/-5.8%, 22+/-11%, and 18+/-12% respectively. Self-reported walking speed, walking impairment-leg weakness, and walking impairment-shortness of breath were also observed to improve significantly for the exercise rehabilitation group alone by 15+/-13%, 25+/-11%, and 28+/-16%, respectively. CONCLUSION: Low-volume exercise rehabilitation can improve activity of daily living-related functional capacity and self-reported functional status of nonanemic dialysis patients.

Activities of Daily Living↗
PubMed2001

Reproducibility of exercise tolerance in patients with end-stage renal disease.

OBJECTIVE: To determine the interday reproducibility of peak and submaximal exercise tolerance of patients with end-stage renal disease (ESRD). DESIGN: Repeated measures. SETTING: Day-patient rehabilitation center. PARTICIPANTS: Twelve consecutively presenting, self-selected patients with ESRD. INTERVENTIONS: All patients performed peak exercise tolerance assessments on a cycle ergometer up to the point of volitional fatigue, with a 1-week interval between the 2 tests. MAIN OUTCOME MEASURES: Cardiopulmonary, hemodynamic, and physical performance parameters were assessed at peak exercise and at the lactate threshold. Standard error of measurement, percentage coefficient of variation (CV%), intraclass correlation coefficient (ICC), and limits of agreement (LOA) were calculated to determine the reproducibility of all variables. RESULTS: CV% (range, 5%-7%) and ICCs (range, .94 - .98) for oxygen uptake and heart rate at peak exercise and lactate threshold indicated highly acceptable levels of group mean reproducibility. LOA analysis revealed satisfactory levels of reproducibility for individual patients. CONCLUSION: Taken together, these reproducibility data may be applied to clinical work, requiring the quantification of changes in the exercise tolerance of patients with ESRD after short-term interventions (eg, exercise training, therapeutic use of recombinant erythropoietin).

Exercise Tolerance↗
PubMed2000

Analysis of the effects of increasing delivered dialysis treatment to malnourished peritoneal dialysis patients.

BACKGROUND: Poor nutrition is associated with a loss of residual renal function and inferior clinical outcome in peritoneal dialysis (PD) patients. The value of increasing the PD dose in these individuals is unclear. METHODS: An open, prospective, longitudinal, "intention to treat" study was performed on a whole PD population. All patients treated during an 18-month recruitment period underwent nutritional assessment and were defined as malnourished if they had a subjective global assessment (SGA) of B or C and were 5% or more below their desirable body weight. These patients received an intended dialysis dose increase of 25% and were reassessed after six months. Dialysis was not increased in the remaining patients, unless dictated by uremic symptoms. RESULTS: Forty-eight of 153 patients were malnourished by the previously mentioned criteria. When compared with well-nourished PD patients, they had evidence of declining nutrition over the previous 12 months, as judged by a loss in body weight and mid-arm circumference (MAC), a reduced creatinine appearance, a reduced appetite for protein and calories, and low plasma albumin. They had been on treatment longer and had less residual renal function, resulting in significantly poorer solute clearances. Their peritoneal membrane function, plasma bicarbonate, comorbid, Karnofsky, Hospital Anxiety and Depression (HAD) scores were not different. Following intervention, their peritoneal Kt/Vurea was increased by 22.5%, and their total Kt/Vurea by 18%, because of a continued loss of residual function. There was also an increase in dialysis-derived calories. Weight and MAC stabilized after an initial deterioration, and creatinine appearance increased. There was no increase in protein intake, as judged by dietetic interview or protein nitrogen appearance. Oral calorie intake improved, as did plasma albumin after an initial decline. Both of these improvements were correlated with the achieved increase in Kt/Vurea. Objective measures of improvement (plasma albumin and protein nitrogen appearance) were significant in those patients without comorbid disease. CONCLUSIONS: These results support the existing evidence that malnutrition is acquired on PD in those patients who lose residual renal function. It is feasible to increase the dialysis dose in these individuals without a detrimental effect, and there is evidence of a modest benefit in patients without comorbidity.

Aged↗
PubMed1999

Impact of peritoneal membrane function on long-term clinical outcome in peritoneal dialysis patients.

It is increasingly clear that peritoneal membrane transport status has clinical implications. The role of the peritoneum in dialysis delivery becomes paramount once residual renal function is lost, particularly as the membrane characteristics may change for the worse with time on treatment. These findings have several important implications: Clinicians need to take solute transport characteristics into account as they assess their patients. Adverse effects of high solute transport include reduced ultrafiltration, solute removal (in particular, sodium), and increased peritoneal protein losses. A need exists to replace lost residual renal function, not just with enhanced solute removal, but also with adequate salt and water removal. The interpretation of urea and creatinine clearances in anuric PD patients needs further consideration and validation. Hypoalbuminemia in PD patients will result from the combined effects of high protein losses, over-hydration, comorbidity, and malnutrition.

Biological Transport↗
PubMed1998

What really happens to people on long-term peritoneal dialysis?

BACKGROUND: Several risk factors for patients treated with peritoneal dialysis (PD) have now been identified. These include age, comorbid disease, nutritional status, loss of residual renal function (RRF) and high peritoneal solute transport. This is not the same, however, as knowing what actually happens to these patients, particularly in the long-term. The purpose of this review was to give as complete a description as is currently possible of the long-term PD patient. METHODS: The literature was surveyed for publications that provide longitudinal cohort data of either selected or unselected patient groups. Detailed data from the Stoke PD Study is presented in the context of these studies. Three principle aspects of what really happens to patients were considered: (1) death, both cause and mode of death; (2) technique failure, with reference to peritoneal function and how the cause of technique failure related to patient survival; and (3) evolution of clinically relevant parameters of patients on PD, such as nutrition and peritoneal function. RESULTS: Sudden death and debilitation were the predominant modes of death, with sepsis playing a contributory role. Debilitation was important regardless of co-existent comorbid disease, and time to death was not influenced by the mode of death. Predominant causes for technique failure remain peritonitis and ultrafiltration, the latter becoming more important with time on treatment. Technical failure is associated with poorer survival, particularly when due to multiple peritonitis or failure to cope with treatment. Cox regression demonstrated that whereas low albumin, loss of RRF and high solute transport predicted patient death, only high solute transport predicted technique failure. Longitudinal changes over the first five years of treatment included loss of RRF, increasing solute transport and following an initial improvement in nutritional state, a decline after two years. Patients surviving long-term PD (at least five years, N = 25) were characterized by prolonged RRF, maintained nutrition and lower solute transport in the medium term. CONCLUSIONS: Several studies of long-term PD in the literature now complement each other in providing a picture of what really happens to PD patients. The links between loss of solute clearance and poor peritoneal ultrafiltration combining to exacerbate sudden or debilitated death and technique failure are emerging. For PD to be successful as a long-term therapy, strategies that maintain nutrition and preserve peritoneal membrane function must be developed.

Cause of Death↗
PubMed1998

Development of a walking test for the assessment of functional capacity in non-anaemic maintenance dialysis patients.

BACKGROUND: Walk tests may be useful adjuncts or even alternatives to the assessment of peak oxygen uptake (VO2 peak) in patients with low functional capacity. Walk tests are easy to administer, appear to be well tolerated by patients and may represent a more meaningful measure for a patient group as they assess capability as well as fitness. However, the use of walk tests for the assessment of functional capacity in maintenance dialysis patients has received scant attention. The aim of this study was to assess the validity of a walking-stair-climbing test to predict VO2 peak in non-anaemic maintenance dialysis patients. METHODS: In the validation phase of the study, 14 subjects completed a cycle ergometer-graded exercise test (GXT) for the determination of VO2 peak and a walking-stair-climbing task (WALK), each separated by a period of 7 days. Three weeks later, 18 subjects completed two WALK tests, each separated by a period of at least 48 h, to facilitate reliability estimation. Estimates of differentiated and undifferentiated ratings of perceived exertion (RPE) were obtained during and immediately consequent to all exercise tests. RESULTS: VO2 peak (ml kg min) was significantly correlated with total WALK time (s) (r = -0.83; P < 0.001). VO2 peak (ml/kg/min) could be predicted from total WALK time with a standard error of prediction of 11%. Reliability assessment revealed no significant differences for any aspect of the WALK test performance, with intraclass correlation coefficients ranging from r = 0.71 (RPElegs) to 0.96 (total WALK time). CONCLUSION: These results indicate that the WALK test is a valid, reliable and potentially useful method by which to assess the functional capacity of non-anaemic maintenance dialysis patients.

Aged↗
PubMed1994

Influence of differing classes of antihypertensive agents on mesangial kinetics following partial renal ablation in rats.

Mesangial kinetics were studied in six groups of rats. Rats were either sham operated or were subjected to 1 1/3 nephrectomy (4/6 Nx). Each group was either untreated or was treated with enalapril (EN) or the drug regimen of hydralazine, hydrochlorothiazide, and reserpine (HHR). Four weeks after surgery rats were injected with iodinated aggregated bovine serum albumin (I-aggBSA) and mesangial localization quantified 2, 4, or 8 h later. Mesangial kinetics in untreated 4/6 Nx rats were characterized by accumulation of I-aggBSA to 4 h after injection with rapid clearance over the 4-8-h period; i.e. mesangial trafficking was increased following 4/6 Nx. Mesangial trafficking in 4/6 Nx rats treated with EN was reduced by virtue of lesser uptake of I-aggBSA at 4 h and retarded clearance over 4-8 h when compared with untreated 4/6 Nx animals. Treatment of 4/6 Nx rats with HHR maintained the increased trafficking observed in untreated 4/6 Nx rats. At 30 weeks untreated 4/6 Nx rats had severe albuminuria and glomerulosclerosis. Both indices of renal damage were significantly less in 4/6 Nx rats treated with enalapril. Treatment with HHR did not prevent albuminuria and had only limited effectiveness in preventing glomerulosclerosis. The different effects of EN and HHR on mesangial trafficking and glomerulosclerosis provide further evidence for a relationship between mesangial trafficking following partial renal ablation and subsequent development of glomerulosclerosis.

Albuminuria↗
PubMed1993

Mesangial kinetics after partial nephrectomy in rats fed a normal or a low-protein diet.

Mesangial kinetics of aggregated BSA (aggBSA) were studied in rats subjected to 1 1/3 nephrectomy (4/6 Nx) fed either a normal (16%) or a low-protein (8%) diet. At 4 weeks postsurgery, ablated rats exhibited modest elevations in blood pressure but had neither significant proteinuria nor evidence of glomerular damage. Following injection of aggBSA into 4/6 Nx rats (16% diet) there was a marked increase in mesangial localization at 4 h compared with control animals, followed by rapid clearance over 4-8 h, in keeping with increased trafficking in this model. The increased trafficking was significantly reduced by dietary protein restriction with 4/6 Nx rats fed an 8% protein diet exhibiting mesangial kinetics not significantly different from control animals. Control animals exhibited identical kinetics irrespective of diet. In separate studies, the 8% protein diet significantly reduced proteinuria and glomerulosclerosis when compared with untreated animals when studied at 30 weeks postsurgery.

Animals↗
PubMed1988

Non-operative management of retroperitoneal fibrosis.

It is generally recognized that in many patients the ureteric obstruction and other manifestations of non-malignant retroperitoneal fibrosis will respond to treatment with corticosteroids. However, most surgeons are reluctant to use steroids as the primary treatment for patients with this condition, mainly because of the risk of mismanagement of malignant retroperitoneal fibrosis. Our experience in the care of 17 patients with non-malignant retroperitoneal fibrosis has led us to believe that an initial non-surgical approach is both safe and preferable.

Adult↗
PubMed1986

Oestrogen-induced changes in renal haemodynamics in the rat: influence of plasma and intrarenal renin.

The effect of oestrone acetate (in total doses of 5 and 10 mg) on systemic and renal haemodynamics and the renin-angiotensin system has been studied in adult female rats. The administration of 10 mg of oestrogen resulted in a significant fall in renal blood flow associated with significant rises in both renal vascular resistance and mean arterial pressure. No changes were noted in cardiac output or total peripheral resistance at either dose. Whilst the higher dose of oestrogen induced a significant increase in plasma renin activity, no change was noted in animals receiving 5 mg of oestrogen. Both regimens caused significant reductions in plasma and intrarenal renin concentrations. Although renal blood flow correlated with plasma renin activity in animals with a normal renal blood flow, no such correlation was noted in animals with oestrogen-induced reductions in renal blood flow. The present study demonstrates that oestrogen-induced reductions in renal blood flow result from a rise in intrarenal vascular resistance which cannot be accounted for by simultaneous changes in either plasma renin activity or renal renin concentration.

Animals↗
PubMed1980

Hydralazine-induced systemic lupus erythematosus: influence of HLA-DR and sex on susceptibility.

26 patients with systemic lupus erythematosus (SLE) induced by treatment with the antihypertensive drug hydralazine were investigated to determine if predisposition to the toxic effect was associated with an HLA-DR antigen. 25 of the 26 patients were slow acetylators. The group was compared with three others (1) 113 healthy subjects, untested for acetylator phenotype, (2) 16 slow-acetylator hypertensive patients treated with hydralazine for more than a year without developing SLE, and (3) 20 patients with idiopathic SLE. The frequency of HLA-DR4 (73%) was significantly higher in the group with hydralazine-induced SLE than in the other groups (respectively 33%, 25%, and 25%). The ratio of women to men affected was 4:1. If the slow acetylators treated with hydralazine were analysed as one group, it was observed that all women with DR4 developed hydralazine-induced SLE; the only men to do so were those with DR2 who were receiving 200 mg hydralazine per day. These observations have led us to suggest guide lines for hydralazine therapy and point to a striking association between an HLA-DR antigen and an adverse reaction to a therapeutic agent. It was also noted that the distribution of DR antigens in the hydralazine-SLE patients was significantly different from that in the group with idiopathic SLE. This supports the view that the syndromes are separate entities.

Acetylation↗
PubMed1977

Oestrogen-associated disease of the renal microcirculation.

The effect of oestrogen-containing compounds on platelet factor 3, platelet life span, renal platelet localization and the fibrinolytic activity of forearm venous blood has been studied in eleven women with the renal vascular abnormalities of the loin pain and haematuria syndrome. The results were compared with those obtained in twenty-nine healthy female volunteer subjects. 2. Platelet factor 3 (PF3) availability was found to be increased in patients with the loin pain and haematuria syndrome during normal menstrual cycles. Oestrogens produced an increase in PF3 availability in both patients and control subjects. 3. Platelet life span was shortened and the index of renal platelet localization increased when patients with the loin pain and haematuria syndrome received oestrogens. No change in platelet kinetics was found in the healthy control subjects receiving oestrogens. 4. The fibrinolytic activity of forearm venous blood, both at rest and after venous occlusion, was increased in the healthy control subjects in response to oestrogens. No such response was seen in the patients with the loin pain and haematuria syndrome. 5. It is suggested that the change in platelet function may be causally related to the intrarenal vascular abnormalities. 6. The possible role of oestrogens in causing these disturbances or unmasking pre-existing abnormalities of platelet function or fibrinolysis is discussed.

Adult↗
PubMed1977

Classical pathway complement activation in association with paraproteinaemia.

Five of twenty-three patients with paraproteinaemia (two IgM, three IgG) have been shown to exhibit marked classical pathway complement activation. The mechanisms of hypocomplementaemia proposed for the five patients are cryoglobulinaemia in one and in vivo immunoglobulin aggregation in the other four. Three further patients had a low C1q and three a low C3 unassociated with any other complement abnormality. No association with any particular IgG subclass or obvious clinical abnormality existed in association with hypocomplementaemia.

Complement C1↗
PubMed1976

The role of C3 in the autologous phase of nephrotoxic nephritis.

The role of complement has been studied in the autologous phase of nephrotoxic nephritis (NTN) in rabbits. No reduction in glomerular fibrin deposition, crescent formation or protection from renal failure was observed in either the standard model of NTN when decomplementing doses of cobra venom factor (CVF) were given before the autologous phase or in a telescoped model when CVF was administered before the nephrotoxic antibody. In the latter situation glomerular fibrin deposition and crescent formation were found in the absence of detectable deposition of C3. However, substantial protection was observed when circulating polymorphonuclear leucocytes (PMN) were depleted by antipolymorph serum. These observations establish the existence of a system of allergic glomerular injury mediated by PMN but independent of C3. It is postulated that this system may account for the glomerular injury seen in patients with Goodpasture's syndrome in whom glomerular C3 deposition is not found.

Animals↗