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Biomedical subjects

N Clyne

Publications and source records attributed to N Clyne.

31 records · Page 2Linked to original sources
PubMed1994

Progressive decline in renal function induces a gradual decrease in total hemoglobin and exercise capacity.

We examined 58 patients (38 men, 20 women; mean age: 45 +/- 12 years; body mass index: 24 +/- 4 kg/m2) with a glomerular filtration rate (GFR) ranging from 3 to 32 ml/min, in order to determine the effects of a progressive decline in renal function on total hemoglobin (THb) and exercise capacity. The THb ranged from 185 to 759 g and the hemoglobin concentration ranged from 66 to 151 g/l. Maximal exercise capacity ranged from 50 to 260 W (40-143% of the expected norm). Nearly all the patients interrupted their exercise tests due to general fatigue, leg tiredness or a combination of these factors. There was a significant partial correlation between THb and GFR after sex and age had been accounted for (r = 0.39; p < 0.005). Maximal exercise capacity and THb showed a significant partial correlation after sex, age and GFR had been accounted for (r = 0.27; p < 0.05). Maximal exercise capacity showed a significant partial correlation with GFR after sex, age and THb had been accounted for (r = 0.30; P < 0.05). In conclusion, there is a gradual decline in THb and maximal exercise capacity as uremia progresses. Anemia appears to be a contributory cause responsible for the decrease in maximal exercise capacity along with other factors pertinent to uremia per se.

Adult↗
PubMed1993

Acute cobalt exposure and oxygen radical scavengers in the rat myocardium.

Excessive amounts of cobalt are cardiotoxic, although the mechanism for this toxicity remains unclear. We studied the effects of acute cobalt exposure on the activities of free radical scavengers in the myocardium in 5 groups of rats. Six rats served as a control group and were given a daily subcutaneous injection of 1 ml saline for 8 days. The other 4 groups of rats received a daily injection subcutaneously of cobalt chloride in doses of 1 mg/kg bw, 5 mg/kg bw, 20 mg/kg bw and 50 mg/kg bw, respectively for 8 days. There was a marked and dose-dependent accumulation of cobalt in the myocardium of the cobalt exposed rats. Creatine kinase, copper-zinc superoxide dismutase (CuZn-SOD) and alpha-tocopherol content did not differ between the control and the cobalt exposed groups. The activity of glutathione peroxidase increased, while the activity of manganese-superoxide dismutase (Mn-SOD) was significantly reduced in the cobalt exposed groups. There was an inverse relationship (r = 0.60, P < 0.0001) between the cobalt content and Mn-SOD activity in the myocardium. These results suggest that acute cobalt cardiotoxicity may involve a reduction of intrinsic scavengers resulting in an increased vulnerability to oxygen free radical toxicity.

Animals↗
PubMed1993

Effects of renal failure on skeletal muscle.

In this cross-sectional study, we examined biopsies from the vastus lateralis muscle of 13 predialytic uremic men (mean age 46 +/- 8 years). Their average glomerular filtration rate was 14 +/- 7 ml/min x 1.73 m2 and their maximal exercise capacity, measured by standardized exercise test on a bicycle ergometer, was 184 +/- 45 W (94% of the expected norm). The proportion of type I fibers (type I%) in the uremic group was similar to that of the reference group (42 +/- 11 vs. 41 +/- 8% NS). The proportion of type IIA fibers (type IIA%) in the uremic group was higher than in the reference group (44 +/- 10 compared to 35 +/- 9%, p < 0.05). The proportion of type IIB fibers (type IIB%) was lower than in the reference group (13 +/- 8 vs. 21 +/- 8%, p < 0.05). Type I fiber area was similar to that of the reference group (4,768 +/- 1,033 vs. 4,627 +/- 1,112 microns 2, NS). Type IIA and type IIB fiber areas tended to be smaller than those of the reference group (type IIA fiber area: 4,515 +/- 929 vs. 5,213 +/- 1,288 microns 2, NS; type IIB fiber area: 3,953 +/- 1,066 vs. 4,406 +/- 1,582 microns 2, NS) with a type IIA area/type I area ratio which was significantly lower than in the reference group. Citrate synthase activity was 0.48 +/- 0.08 mu kat/g in the uremic group and 0.50 +/- 0.08 mu kat/g in the reference group, NS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of erythropoietin treatment on physical exercise capacity and on renal function in predialytic uremic patients.

Anemia is already present in patients with moderate renal failure and is a major cause of the decline in exercise capacity seen in these patients. We examined the effects of erythropoietin (EPO) treatment in 12 predialytic uremic patients (EPO group: mean age 46 +/- 12 years; 6 men, 6 women) with a mean glomerular filtration rate (GFR) of 10 +/- 4 ml/min x 1.73 m2. These patients were compared to a control group of 8 patients (5 men, 3 women). The observation period was 3 months. The EPO group received 300 U/kg body weight i.v. once a week. The EPO group increased their total hemoglobin (THb) from 323 +/- 89 to 466 +/- 128 g (p less than 0.001) and their hemoglobin concentration from 86 +/- 8 to 117 +/- 11 milligrams (p less than 0.001). Their exercise capacity, measured by a standardized exercise test on a bicycle ergometer, increased from 128 +/- 45 to 147 +/- 57 W (p less than 0.01). The control group did not change their THb (349 +/- 124 and 357 +/- 131 g), hemoglobin (93 +/- 8 and 94 +/- 10 milligrams) or exercise capacity (98 +/- 49 and 101 +/- 50 W) during the observation period. There was a significant correlation between the increase in THb and the increase in exercise capacity in the EPO group (r = 0.81, p less than 0.005). The GFR was unchanged in both groups (EPO group: 10 +/- 4 and 10 +/- 6 ml/min x 1.73 m2; control group: 8 +/- 3 and 8 +/- 3 ml/min x 1.73 m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Binding of dietary cobalt to sarcoplasmic reticulum proteins.

It has previously been shown that cobalt accumulates in the myocardium of rats, mainly the sarcoplasmic reticulum (SR) and the mitochondrial inner membrane. In order to investigate the mode of accumulation of cobalt in the SR, rats were given a dietary cobalt supplementation of 40 mg of CoSO4 x 7H2O kg-1 body wt, after which the rats were sacrificed and the sarcoplasmic reticulum was isolated. The SR proteins were subjected to analysis by polyacrylamide gel electrophoresis followed by protein staining and determination of the content of cobalt in each protein band. The major cobalt-binding protein was found to have a molecular weight of about 100,000; a 200,000 molecular weight protein was also found to bind cobalt, although less extensively. These results suggest that cobalt is bound to the monomeric and dimeric forms of Ca(2+)-ATPase in the SR of the myocardium.

Animals↗
PubMed1991

Effects of exercise training in predialytic uremic patients.

We examined the effects of physical training in 10 predialytic uremic patients (7 men, 3 women, mean age 47 +/- 8 years) with an average glomerular filtration (GFR) of 15 +/- 7 ml/min x 1.73 m2. All 10 patients participated in an exercise programme 3 times/week for 3 months and were compared to a control group of 9 patients with comparable baseline variables. The exercise group increased its maximal exercise capacity measured by standardized exercise test on a bicycle ergometer, from an average 159 +/- 49 to 174 +/- 57 W (p less than 0.01). They also showed a decrease in heart rate at equal load (138 +/- 29-123 +/- 18 beats/min, p less than 0.05). The control group did not change its exercise capacity (171 +/- 60 and 171 +/- 65 W, respectively, NS), nor its heart rate at equal load (124 +/- 24 and 123 +/- 24 beats/min, respectively, NS). Thigh muscular function assessed by static endurance increased from a median 77 s (range 27-197) to 113 s (range 66-201), p less than 0.002. Dynamic muscular endurance increased from a median number of 41 movements (range 28-105) to 93 movements (range 45-139), p less than 0.001. The corresponding figures for the controls were: static endurance 60 (range 20-209) and 47 s (range 9-203), respectively, NS; dynamic endurance 53 (range 19-190) and 43 movements (range 10-126), respectively, NS. Total hemoglobin, blood volume, GFR, blood pressure and echocardiographic variables remained unchanged during the observation period. We conclude that in predialytic uremic patients, physical training improves exercise capacity mainly due to an improved muscular function.

Adult↗
PubMed1990

The effect of cobalt on mitochondrial ATP-production in the rat myocardium and skeletal muscle.

Cobalt has been shown to accumulate in the myocardium of uraemic patients and has been suggested as a myocardial toxin inhibiting mitochondrial respiration. In order to study the cellular effects of cobalt exposure three groups of rats (n = 12 per group) were fed a diet containing 12% protein without supplementation or with 20 mg and 40 mg CoSO4 7 H2O/kg body weight/day respectively. After 8 weeks the hearts and soleus muscles were removed. Cobalt in tissues and in four cell fractions were analysed with neutron-activation analysis (ng/g wet weight and ng/mg protein respectively). Mitochondrial respiration was analysed as ATP-production rate using pyruvate + malate and palmitoyl-carnitine + malate as substrate. The ATP-production from pyruvate + malate was unchanged in both heart and skeletal muscle in the exposed animals. With palmitate as substrate, the heart muscle showed a slightly lower ATP-production rate (p less than 0.05) after the 20 mg cobalt dose, but the rate was unchanged in the group with higher cobalt intake. No changes in ATP-production rate from palmitate was observed in soleus muscle. The microsomal (100,000 g) fraction in the myocardial cells contained significantly higher cobalt concentrations compared to the mitochondrial fraction in both the unexposed (1.4 ng/mg protein vs 0.19, p less than 0.05) and exposed rats (53.4 ng/mg protein vs 13.2, p less than 0.005). In conclusion, cobalt showed a large accumulation in myocardial cells, without significant effects on mitochondrial ATP-formation rate from oxidation of pyruvate or palmitate and with the highest cobalt content contained in the microsomal (100,000 g) fraction.

Adenosine Triphosphate↗
PubMed1990

The intracellular distribution of cobalt in exposed and unexposed rat myocardium.

The intracellular distribution of cobalt was analysed in the myocardium of exposed and unexposed rats. The exposed rats were given a dietary cobalt supplementation of 40 mg CoSO4.7 H2O/kg body weight for 8 weeks. The mitochondrial fraction showed the greatest relative increase in cobalt: 0.09 ng/mg protein in the unexposed rats to 8.43 ng/mg protein in the exposed rats. In the exposed rats the submitochondrial particles had the highest levels of cobalt: 19.43 ng/mg protein, followed by the sarcoplasmatic reticulum: 12.3 ng/mg protein. The microsomal 44,000 g supernatant also showed an increase, although the levels remained low (0.51 ng/mg protein in the exposed animals). Apparently the calcium-storing organelles had the highest levels of cobalt. This could affect calcium flux in myocardial cells and, secondarily, tension development in cardiac muscle.

Animals↗
PubMed1989

Factors influencing physical working capacity in renal transplant patients.

Clyne N, Jogestrand T, Lins L-E & Pehrsson SK. Division of Nephrology and Cardiology, Department of Medicine and Department of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden. We have examined uraemic patients' exercise capacity, and the factors influencing this capacity, before and after successful renal transplantation. Eleven uraemic patients (mean age 41 +/- 10 years) with an average glomerular filtration rate (GFR) of 5 +/- 4 ml/min x 1.73 before and 45 +/- 19 ml/min x 1.73 after transplantation participated in the study. The maximal exercise capacity, measured by standardized exercise test on a bicycle ergometer, averaged 106 +/- 25 W before and 126 +/- 35 W (p less than 0.05) after transplantation. The patients interrupted the tests prior to and after transplantation because of general fatigue, leg tiredness or both. No patient experienced angina pectoris. All, but one, had a normal ECG reaction during exercise. Total haemoglobin (THb) was 55 +/- 8% of the expected normal before and 84 +/- 19% after transplantation (p less than 0.01). The increase in working capacity was linearly correlated to the increase in THb (r = 0.84, p less than 0.01), but not to the improvement in GFR nor to the decrease in parathyroid hormone. In conclusion, successful renal transplantation improves working capacity. The results indicate that an increased THb is a major determinant for this increase in working capacity.

Adult↗
PubMed1987

Factors limiting physical working capacity in predialytic uraemic patients.

The exercise capacity of 20 predialytic uraemic patients (mean age 43 +/- 12 years) was studied prospectively. Nine of these patients were examined twice in a longitudinal study. The maximal working capacity, measured by standardized exercise test on a bicycle ergometer, averaged 74 +/- 19% of the expected normal. Normal exercise ECG were registered in 16 out of 20 patients. Total hemoglobin/kg body weight (THb) was 67 +/- 16% of the expected normal and serum parathyroid hormone concentration (PTH) was 39 +/- 39 micrograms/l (normal range 0.5-1.5). Partial correlation showed a correlation between exercise capacity and PTH (p less than 0.05). In the longitudinal study the decrease in steady state exercise capacity was correlated to the decrease in THb (p less than 0.05), but not to the increase in PTH. In conclusion, patients with predialytic uraemia have a reduced maximal working capacity, due to several possible factors one of which is a reduced THb. Ischaemic heart disease seems to be of minor importance.

Adult↗
PubMed1986

Occurrence and significance of heart disease in uraemia. An autopsy study.

The occurrence of heart disease in uraemic patients was evaluated from study of 94 autopsied cases of chronic renal failure. The most common autopsy-ascertained causes of death were congestive heart failure (37%), acute myocardial infarction (13%) and tamponading pericarditis (8%). Death from congestive heart failure was significantly more common among the patients aged 60 or more than in the younger group. Hypertension was recorded in 59% of the patients, including all those with fatal myocardial infarction. Coronary arteriosclerosis was graded as absent to mild in about 40% of the patients. More severe grades occurred predominantly in the older patients. Tamponading pericarditis almost exclusively affected patients in haemodialysis. The authors conclude that most deaths among patients with end-stage renal failure were due to congestive heart failure. Ischaemic heart disease did not seem to be a more common cause of death than in the general population.

Adult↗
PubMedDate not supplied

Improving the nurse-patient relationship: a multi-faceted approach.

AIM: A Corporate Education Session was held to provide concrete strategies for overcoming several specific barriers in the daily nurse-patient relationship that negatively affect the patient, nurse, or both, and to provide the latest information about best practice as it affects nurses in renal care. METHODOLOGY: The session was led by a moderator who presented three video case studies to the audience. Communication strategies for recognising and overcoming nurse-patient communication barriers were presented. The audience expressed their views about each case study using voting pads, and a panel of experts addressed the comments of the audience and discussed guidelines for best practice in renal care. The panel comprised three experienced renal nurses, a senior nephrologist, and an expert in social interaction. CONCLUSIONS: Optimal treatment of patients with renal disease should include early treatment of anaemia, adequate levels of dialysis, and a multidisciplinary approach, responding to both the medical and the social needs of the patient.

Aged↗