Browsing by Person "Naish, P. F."

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An alternative histochemical method to simultaneously demonstrate muscle nuclei and muscle fibre type
(Springer Verlag, 2003-06) Sakkas, G. K.; Ball, Derek; Mercer, Tom; Naish, P. F.
We present a modified histochemical method to examine, simultaneously, nuclei and fibre type in human skeletal muscle. The new procedure (Haem-ATPase) is based on two previously used histochemical protocols. Biopsies were obtained from the rectus abdominis muscle of patients undergoing elective abdominal surgery. Fibre type composition, cross-sectional area (CSA) and nuclei to fibre ratio (N:F) were determined from frozen sections of each biopsy. To test the validity of the new method, serial sections of each biopsy were stained separately using the standard and modified methods. No differences were found in fibre type distribution, mean-weighted CSA and N:F when comparing the modified method with the standard methods. The Haem-ATPase method was found to shrink fibre size by at least 3% (P>0.05) compared with the established myosin acid labile method. We propose that this modified technique is suitable for initial examination of both the nuclei and fibre type in the same frozen sections of human skeletal muscle.
Atrophy of non-locomotor muscle in patients with end-stage renal failure
(Oxford University Press, 2003) Sakkas, G. K.; Ball, Derek; Mercer, Tom; Sargeant, A. J.; Tolfrey, K.; Naish, P. F.
Background. All previous histological studies of skeletal muscles of patients with renal failure have used locomotor muscle biopsies. It is thus unclear to what degree the observed abnormalities are due to the uraemic state and how much is due to disuse. The present study was undertaken to attempt to investigate this question by examining a non-locomotor muscle (rectus abdominis) in patients with end-stage renal failure. Methods. Biopsies from rectus abdominis were obtained from 22 renal failure patients (RFPs) undergoing surgical Tenchkoff catheter implantation for peritoneal dialysis and 20 control subjects undergoing elective abdominal surgery. Histochemical staining of frozen sections and morphometric analysis was used to estimate the proportion of each fibre type, muscle fibre area and capillary density. Myosin heavy chain composition was examined by SDS-PAGE. Results. There were no differences in fibre type distribution between RFPs and controls. All RFPs showed fibre atrophy [mean cross-sectional area (CSA) 3300 1100 m2, compared to 4100 1100 m2 in controls (P < 0.05)]. All fibre types were smaller in mean CSA in RFPs than in controls (15, 26 and 28% for types I, IIa and IIx, respectively). These differences could not be accounted for by differences in age, gender or cardiovascular or diabetic comorbidity. Muscle fibre capillarization, expressed as capillaries per fibre or capillary contacts per fibre, was significantly less in RFPs. Conclusions. Since a non-locomotor muscle was examined, the effects of disuse as a cause of atrophy have been minimized. It is likely, therefore, that the decreased muscle fibre CSA and capillary density of RFPs compared to controls were due predominantly to uraemia itself.
Changes in muscle morphology in dialysis patients after 6 months of aerobic exercise training
(Oxford University Press, 2003-09) Sakkas, G. K.; Sargeant, A. J.; Mercer, Tom; Ball, Derek; Koufaki, Pelagia; Karatzaferi, C.; Naish, P. F.
Background. In the present study we investigated the effect of a 6-month aerobic exercise programme on the morphology of the gastrocnemius muscle of end-stage renal disease (ESRD) patients. Methods. Twenty-four ESRD patients volunteered to participate in the training programme and underwent muscle biopsy before training. Eighteen patients completed the training programme of whom nine agreed to a post-training biopsy (one woman and eight men, mean age 56 15 years). Data are presented for the nine subjects who were biopsied before (PRE) and after training (POST) and separately for the 15 subjects for whom we only have a biopsy before training (cross-sectional group). Results. There were no significant differences (P > 0.05) in fibre type distribution or myosin heavy chain (MyHC) expression between the cross-sectional and PRE/POST groups. The mean cross-section fibre area after training (POST) increased by 46% compared with the PRE training status (P < 0.01). The proportion of atrophic fibres decreased significantly after training in type I, IIa and IIx fibre populations (from 51 to 15%, 58 to 21% and 62 to 32%, respectively). Significant differences were also found in capillary contact per fibre (CC/F), with the muscle having 24% (P < 0.05) more CC/F compared with the PRE training status. No significant differences in cytochrome c oxidase concentration were found between the groups. Conclusions. In conclusion, exercise appeared to be beneficial in renal rehabilitation by correcting the fibre atrophy, increasing the cross-section fibre area and improving the capillarization in the skeletal muscle of renal failure patients.
Development of a walking test for the assessment of functional capacity in non-anaemic maintenance dialysis patients
(Oxford University Press, 1998-08) Mercer, Tom; Naish, P. F.; Gleeson, Nigel; Wilcock, J. E.; Crawford, C.
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. VO 2 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 test-retest 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
Dialysis mode does not affect exercise intolerance of patients with end-stage renal disease.
(2001) Koufaki, Pelagia; Mercer, Tom; Naish, P. F.
Effects of exercise training on aerobic and functional capacity of end-stage renal disease patients
(Scandinavian Society of Clinical Physiology and Nuclear Medicine, 2002-05-28) Koufaki, Pelagia; Mercer, Tom; Naish, P. F.
The aim was to assess the effects of exercise training on aerobic and functional capacity of patients with end-stage renal disease (ESRD). Patients completed an incremental exercise test on a cycle ergometer to determine VO2 peak and VO2 at ventilatory threshold (VT; V-slope). On a separate day they performed two constant load exercise tests on a cycle ergometer at 90% of VT and at a workload of 33 W, to determine VO2 kinetics. Functional capacity was assessed using measurements of sit-to-stands (STS-5, STS-60) and a walk test. Dialysis patients were randomly allocated to an exercise (ET: n=18, age=573 years) or control (C: n=15, age=505 years) group. The ET group participated in an exercise training programme involving cycling for 3 months. Repeated measures ANOVA revealed significant time by group interactions (P < 005) following training for VO2 peak (ET: 17 61 versus 199 63, C: 195 47 versus 188 49 ml kg min-1) and VO2-VT (ET: 107 35 versus 118 33, C:129 32 versus 119 35 ml kg min-1). VO2 kinetics remained unchanged in both groups at 90% -VT, but a trend (P=0059) towards faster kinetics at the 33 W was observed (ET: 496 195 versus 378 127, C: 428 13 versus 494 202 s). Significant time by group interactions (P < 005) were also observed for STS-5 (ET: 147 62 versus 110 33, C: 128 44 versus 127 48 s) and STS-60 measurements (ET: 212 72 versus 269 62, C: 237 68 versus 241 72). Three months of exercise rehabilitation significantly improves peak exercise capacity of patients with ESRD. Measurements of VO2 kinetics and functional capacity suggest that longer time might be needed to induce peripheral adaptations.
Improvement in quality of life of dialysis patients during six months of exercise
(European Renal Care Association, 2002) Pugh-Clarke, K.; Koufaki, Pelagia; Rowley, V.; Mercer, Tom; Naish, P. F.
Quality of life (QOL) assessment has rapidly become an integral variable of outcome in clinical research; over 1,000 new articles each year are indexed under quality of life (1). Despite the proliferation of instruments and the burgeoning theoretical literature devoted to QOL evaluation, no unified approach has been derived for its measurement, and little agreement has been attained on what it means (2). Lack of clarity regarding the definition of QOL has led to several related concepts, namely functional status, life-satisfaction, well-being, and health status, being used interchangeably with QOL (3), further contributing to ambiguity. Compared to the general population, patients with end-stage renal disease (ESRD) experience a poorer QOL (4). Questionnaire-based QOL measurement in ESRD has demonstrated that QOL is best in renal transplantation and worst in unit-based haemodialysis. The main determinants of difference are the physical function domains. QOL in ESRD has traditionally been measured by a number of disease-specific, domain-specific and generic instruments, all exhibiting a fixed design. However, the fixed nature of the aforementioned instruments, is problematic in that what is measured is predetermined and hence may not represent the free choice of the individual whose QOL is assessed (5). Questionnaire-based instruments may not reflect individual priorities.
Low-Volume Exercise Rehabilitation Improves Functional Capacity and Self-Reported Functional Status of Dialysis Patients
(Lippincott, Williams & Wilkins, 2002-05) Mercer, Tom; Crawford, C.; Gleeson, Nigel; Naish, P. F.
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 pa
Nutritional status, functional capacity and exercise rehabilitation in end-stage renal disease
(Dustri -- Verlag Dr Karl Feistle, 2004) Mercer, Tom; Koufaki, Pelagia; Naish, P. F.
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 functionalcapacity. 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.
Patients receiving maintenance dialysis have more severe functionally significant skeletal muscle wasting than patients with dialysis-independent chronic kidney disease
(Oxford University Press, 2006-08) McIntyre, C. W.; Selby, N. M.; Sigrist, M.; Pearce, L. E.; Mercer, Tom; Naish, P. F.
Background. Chronic renal replacement therapy patients exhibit reduction in skeletal muscle function as a result of a combination of metabolic effects and muscle fibre size reduction. The aim of this study was to compare muscle mass with function in patients with chronic kidney disease (CKD) at stages 4 and 5 on haemodialysis (HD) and peritoneal dialysis (PD), and investigate the associations of muscle wasting in a cross-sectional cohort. Methods. We studied 134 patients (60 HD, 28 PD and 46 CKD 4). The three groups were well matched for age, sex, diabetes and dialysis vintage. Cross-sectional area (CSA) of muscle and fat was measured from a standardized multi-slice CT scan of a 6 cm long section of thigh. CSA of soft tissue was taken from appropriate fat and muscle densities. Functional assessment was by the sit-to-stand 60 test, assessing both the number of sit-to-stands possible under controlled conditions in 60 s (STS 60), and the time taken to perform five sit-to-stand movements (STS 5). Data were collected on a wide range of potential determinants of muscle CSA. Results. There were no significant differences in haemoglobin between males or females or between any of the groups studied. Serum phosphate and calcium-phosphate product were higher in HD patients as compared to CKD4 patients, but there were no differences in these variables when comparing PD patients with either CKD4 or HD patients. Muscle CSA correlated well with objective functional assessments in males (STS 60 R = 0.52, P<0.0001) and females (R = 0.41, P = 0.004), and STS performance was reduced in dialysed patients as compared with CKD 4. Univariate analysis demonstrated that muscle CSA was associated with serum albumin concentration (R = 0.49, P<0.0001), age (R = -0.35, P = 0.005) and C-reactive protein (R = -0.34, P = 0.004). Creatinine clearance, dialysis adequacy, dialysis vintage and time-averaged serum bicarbonate, calcium and phosphate concentrations were not correlated with muscle CSA. Conclusion. In conclusion, patients with dialysis-treated CKD 5 exhibited more functionally significant muscle wasting than patients with CKD 4. This may be amenable to modification with targeted exercise or amelioration of factors associated with observed differences in muscle mass
Physical dysfunctioning in patients with renal failure.
(Hayward Group Ltd, 1999) Naish, P. F.; Mercer, Tom
Muscle wasting and weakness are common features in patients on dialysis. Anorexia, acidosis, malnutrition,1,2 increasing age, cardiovascular comorbidity and physical inactivity are all contributors to this state. Muscle weakness, as well as being a significant cause of impaired aerobic power, can mean that ordinary activities of daily living are serious challenges to many dialysis patients.
Physical function assessment in chronic kidney disease
(Hayward Group Ltd, 2010) Koufaki, Pelagia; Naish, P. F.; Mercer, Tom
Measures of physical function have been shown to be related to clinically important outcomes (survival, morbidity and quality of life [QoL]) in patients receiving dialysis-based renal replacement therapy. Given the prognostic potential of these factors, it is recommended that their measurement should form part of the routine assessment (and management) of patients receiving maintenance dialysis therapy. The available literature suggests that, if good practice is followed, exercise tolerance and functional capacity assessment of the patient with chronic kidney disease (CKD) (stages 3-5) is safe, feasible and may be clinically useful.
Quality of life in chronic kidney disease
(Wiley-Blackwell, 2006-07) Pugh-Clarke, K.; Naish, P. F.; Mercer, Tom
Background - Quality of life (QOL) is suboptimal in end-stage renal disease. However, studies indicate that QOL is already impaired prior to the initiation of renal replacement therapy, implying that the initial decline originates in the chronic kidney disease (CKD) phase of the renal disease trajectory. Given the significance of QOL as a clinical outcome, there is a paucity of QOL research in CKD. Aims - To measure QOL at three distinct phases (based on creatinine clearance - Ccr) of the disease trajectory in CKD: normal renal function (NRF) with underlying renal disease, moderate CKD, and advanced CKD (Ccr >=75, 40-60, and <=30 ml/minute, respectively), and to establish if QOL is different between these groups. Methods - Data was collected from 25 patients from each of the Ccr bands (N=75). We measured self-reported QOL (Schedule for the Evaluation of Individual Quality of Life - SEIQOL), uraemic symptoms (Leicester Uraemic Symptom Scale - LUSS), and laboratory variables. Results - SEIQOL was significantly lower (p<0.001), and symptom number, frequency, and intrusiveness significantly higher (all p<0.001) in the advanced CKD group when compared to the NRF group. Although SEIQOL and symptom intrusiveness did not differ between the advanced and moderate CKD groups, SEIQOL was significantly lower (p<0.05) and symptom intrusiveness significantly higher (p<0.05) in the moderate CKD group when compared to the NRF group. Conclusion - QOL is already impaired in moderate CKD. The significant difference in QOL and symptom intrusiveness between the moderate CKD and NRF groups may denote a causal relationship between symptom intrusiveness and QOL early in CKD.
Reliability of indices of neuromuscular leg performance in end-stage renal failure
(Taylor & Francis, 2002) Gleeson, Nigel; Naish, P. F.; Wilcock, J. E.; Mercer, Tom
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 knee flexion angle [0 = 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.
Reproducibility of exercise tolerance in patients with end-stage renal disease
(Elsevier, 2001-10) Koufaki, Pelagia; Naish, P. F.; Mercer, Tom
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). Key Words: Exercise tolerance; Kidney failure, chronic; Rehabilitation; Reproducibility of results.
Skeletal muscle morphology and capillarization of renal failure patients receiving different dialysis therapies
(2004) Sakkas, G. K.; Ball, Derek; Sargeant, A. J.; Mercer, Tom; Koufaki, Pelagia; Naish, P. F.
The morphology of gastrocnemius muscles was examined in RFPs (renal failure patients) being treated using HD (haemodialysis) and CAPD (continuous ambulatory peritoneal dialysis). RFPs (n=24) volunteered to participate in the present study. Twelve RFPs (five women and seven men; mean age, 55 years) were undergoing CAPD treatment and 12 RFPs (two women and ten men; mean age, 62 years) were undergoing HD treatment. Muscle biopsies from gastrocnemius muscles were found not to differ (P>0.05) in fibre type distribution, MyHC (myosin heavy chain) expression or fibre CSA (cross-sectional area) between the two groups. There were, however, significant differences (P<0.05) in CC/F (capillary contact/fibre), C/F (capillary to fibre ratio) and cytochrome c oxidase activity. The HD group had 33% more CC/F, with a 19% higher C/F and 33% greater cytochrome c activity in glycolytic fibres (II) than the CAPD group. There were no apparent differences in age, gender, co-morbidity, self-reported physical activity or physical functioning between the two groups, which could account for the difference in muscle capillarity between the groups. The HD patients were, however, administered heparin as a routine part of the dialysis therapy. The possibility is discussed that heparin in combination with mild anaemia and acidosis may have augmented angiogenesis in the HD patients.