Biomedical subjects

M C Robertson

Publications and source records attributed to M C Robertson.

At least 19 recordsLinked to original sources

PubMed1995

Oxidation of low density lipoproteins from patients with renal failure or renal transplants.

Peroxidation of low density lipoproteins (LDL) may be involved in the development of atherosclerosis which is prevalent in patients with chronic renal failure and renal transplant recipients. We determined the copper ion catalyzed oxidation in vitro, vitamin E content, and chemical and fatty acid composition of LDL isolated from 38 patients with renal disease and 15 healthy subjects. Also the acute effect of hemodialysis treatment on LDL oxidation variables was tested. The lag time in conjugated diene formation during oxidation was significantly (P = 0.011) shorter in LDL from renal transplant recipients (66 min, N = 18) mainly due to significantly (P < 0.05) shorter times in women (47 min, N = 7), compared with healthy subjects (83 min, N = 15), patients on hemodialysis (91 min, N = 13) and patients treated by continuous ambulatory peritoneal dialysis (CAPD) (82 min, N = 7). The maximum rate and the extent of LDL oxidation were significantly (P < 0.01) lower in all patients with renal disease compared with healthy subjects. The triglyceride content of LDL was significantly (P < 0.001) higher in women with kidney grafts (7.3%) compared with levels in the corresponding men (5.3%) and healthy women (5.0%), and was correlated significantly with the lag time in LDL oxidation in renal transplant recipients (Spearmans r = -0.502, P = 0.034). The percentage oleic acid in LDL was significantly higher (P = 0.002) and the percentage linoleic acid was significantly lower (P = 0.046) in patients with renal disease, and may largely account for their lower rates and extent of LDL oxidation. Levels of the LDL oxidation variables and organic lipid peroxide content of LDL were not significantly different before and after hemodialysis and 24 hours later. These results suggest that LDL from women with renal transplants may be abnormally susceptible to oxidation possibly due to increased triglyceride content.

Adult↗

PubMed1995

Control over future health in old age: characteristics of believers and sceptics.

In a cross-sectional study of a total population aged 70 years and over in a rural New Zealand township (sample size 682) we investigated factors which characterize those who felt they had a great deal of control and those who felt they had little or no control over future health. In a significant logistic regression model those with a feeling of a great deal of control over future health had a lower prevalence of chronic obstructive lung disease, higher prevalence of diabetes, took less alcohol, were more likely to be satisfied with bowel function, had a lower protein intake, were more likely to participate in strenuous to moderate activity and were less likely to have features of depression. Different perceptions of control were associated with significant differences in health practices and health status.

Aged↗

PubMed1995

Plasma clearance, tissue uptake and expression of pituitary peptide 23/pancreatitis-associated protein in the rat.

The secretion of peptide 23 by rat pituitary cells is stimulated by growth hormone-releasing hormone and inhibited by somatostatin. Recent cloning of the cognate cDNA for peptide 23 revealed that it is identical to pancreatitis-associated protein (PAP). In the present study, the clearance and tissue uptake of recombinant peptide 23/PAP in normal adult male rats was assessed. The plasma half-life of recombinant peptide 23/PAP was 4.8 +/- 1.4 (S.D.) min. Maximal accumulation of radio-labelled peptide 23/PAP was observed in the kidney, stomach, small intestine and pancreas whereas negligible uptake was seen in the liver, lung or heart. Peptide 23/PAP was detected in a variety of tissue extracts using a radioimmunoassay. Extracts of ileum contained the highest concentrations of peptide 23/PAP. In situ hybridization analysis showed that peptide 23/PAP mRNA was highly expressed in the columnar epithelial cells of ileum, jejunum and duodenum. These observations demonstrate that peptide 23/PAP, a protein previously thought to be of pituitary origin, is widely expressed in the gastrointestinal tract and that it is rapidly removed from the circulation by the kidney and by tissues which express peptide 23/PAP.

Animals↗

PubMed1995

Cholesterol precursor concentration in plasma from patients with chronic renal failure or kidney grafts.

Plasma lathosterol concentration which is an index of cholesterol synthesis rate was measured in 36 patients with chronic renal failure (CRF) including 13 who were dialysis independent, 12 receiving hemodialysis and 11 on continuous ambulatory peritoneal dialysis (CAPD), 17 renal transplant recipients and 27 healthy control subjects. Concentrations of plasma lathosterol were significantly (ANOVA p = 0.03) lower in all categories of renal patients excepting those treated by CAPD, compared with control values. In normolipidemic subjects (cholesterol < or = 6.50 mmol/l and triglycerides < or = 2.0 mmol/l) plasma lathosterol levels in hemodialysis patients and renal transplant recipients were still significantly (ANOVA p = 0.02) lower than control values. In transplant recipients, the plasma lathosterol/cholesterol ratio was significantly (p = 0.02) lower than those treated with azathioprine and prednisone compared with those treated with these drugs and cyclosporin. Significant (p < 0.001) positive correlations were recorded between plasma lathosterol concentration and plasma levels of apolipoprotein B (apoB) and very low density lipoprotein (VLDL) lipids in the renal patients. These data suggest that the rate of cholesterol synthesis may be low in undialysed and hemodialysed patients with CRF and in renal transplant recipients, particularly those treated with double therapy, and may be linked to the metabolism of apoB and VLDL.

Adolescent↗

PubMed1995

Cell cholesterol transport to plasma in blood from patients with renal failure or a kidney transplant.

Accumulation and distribution of cell cholesterol in plasma lipoproteins of incubated blood was examined in 36 patients with chronic renal failure including 13 who were dialysis-independent, 12 on haemodialysis, and 11 on continuous ambulatory peritoneal dialysis (CAPD), 17 renal transplant recipients, and 8 healthy controls. In addition, transport of cholesterol between red blood cells and high-density lipoprotein subfraction 3 (HDL3) isolated from a subgroup of patients with chronic renal failure was determined. Significantly less cell cholesterol appeared in plasma (P < 0.002) and HDL (P = 0.03), the main recipient of cell cholesterol, in patients with chronic renal failure compared with healthy subjects. Corresponding values in blood from renal transplant recipients were similar to controls. In patients with chronic renal failure, plasma HDL3 cholesterol levels (P < 0.02), HDL3 phospholipid content (P < 0.001) and net transport of red cell cholesterol to isolated HDL3 (P < 0.001) were significantly lower compared with controls. The data suggest that in patients with chronic renal failure, low levels of plasma HDL3 of abnormal composition may restrict the incorporation of cell cholesterol into the antiatherogenic HDL fraction potentially leading to inefficient transport of cholesterol from peripheral tissues and the development of atherosclerosis. These abnormalities appear to be reversed by renal transplantation.

Adolescent↗

PubMed1995

Urban/rural differences in red blood cell fatty acid composition, plasma lipids and diet in Melanesian Fijians.

OBJECTIVE: The aim of the study was to compare red blood cell (RBC) fatty acid composition, plasma lipids and lipoproteins and dietary intake between urban and rural Melanesian Fijians. DESIGN: A cross-sectional study was performed in a random subsample (n = 154) from a total survey population of 589 subjects. SETTING: Melanesian Fijians living in the relatively urban settlement of Nabua, Suva and On the remote island of Qamea (rural) were studied. RESULTS: The proportions of myristic acid (1.4% versus 0.3%, P < 0.001) and arachidonic acid (10.1% versus 11.4%, P < 0.01) were significantly higher and proportions of oleic acid (14.4% versus 13.2%, P < 0.05) and linoleic acid (11.9% versus 8.1%, P < 0.001) were significantly lower in RBC from rural compared with urban men, and a similar pattern was seen in women. Plasma cholesterol levels were significantly (P < 0.05) higher in the rural subjects. Urban/rural differences in plasma cholesterol levels were not significant when the proportion of RBC myristate was taken into account. CONCLUSIONS: The results suggest that consumption of myristic acid from coconut fat is greater and the intake of linoleic acid is less in Fijians living on a remote island and may contribute to their higher plasma cholesterol levels compared with their urban counterparts.

Adolescent↗

PubMed1994

Cholesteryl ester transfer in patients with renal failure or renal transplants.

Plasma newly-synthesized cholesteryl ester transfer (NCET) rate and concentrations of lipids, lipoproteins and apolipoproteins A1 and B were measured in chronic renal failure patients (dialysis independent and dialysis dependent), patients with a functioning renal transplant and in healthy control subjects with comparable ages and plasma triglycerides. Plasma NCET rates and apoB concentrations were significantly higher in patients treated by continuous ambulatory peritoneal dialysis (CAPD) compared with controls. In normolipidemic subjects (cholesterol < 6.5 mmol/liter, triglycerides < 2.0 mmol/liter), plasma NCET rates did not differ significantly from rates in the corresponding control subjects. In hyperlipidemic subjects, plasma NCET rates were significantly higher than rates in the normolipidemic subgroup. Plasma NCET rates were correlated closely with plasma apoB levels in all renal patients combined (r = 0.754, N = 53, P < 0.001) and with plasma cholesteryl ester mass transfer (r = 0.853, N = 13, P < 0.001). We conclude that, in the absence of hyperlipidemia, plasma NCET rate is normal in patients with chronic renal failure irrespective of the treatment for uremia, and when hyperlipidemia is present NCET rates are raised and may contribute to elevated levels of the proatherogenic apoB-containing lipoproteins.

Adolescent↗

PubMed1994

Is low blood pressure in elderly people just a consequence of heart disease and frailty?

Low blood pressure has been associated with increased mortality in older people, but it is unclear whether the hypotension is a risk in its own right or just a marker of disease. In this study we investigated the extent to which those in the lowest decile of systolic and diastolic pressures could be predicted by measures of cardiovascular disease and frailty. We studied 782 people 70 years and over drawn from the only group of general practices in a rural township. Hypotension was defined separately for systolic and diastolic blood pressures as a pressure less than the tenth percentile for the sample as a whole. This was a systolic pressure of < or = 122 mmHg and a diastolic pressure of < or = 68 mmHg. There was a significant relationship between low systolic blood pressure and male sex, history of myocardial infarction by questionnaire and low body mass index (BMI), and between low diastolic pressure and male sex, history of angina and myocardial infarction, use of one or more hypotensive drugs, low BMI, low corrected arm muscle area, low self-maintenance score and the use of two or more home services. There was no association with ECG abnormalities. In the multivariate analysis only 4.2% of those with low diastolic pressure and none of those with low systolic pressure could be correctly classified. Hypotension in old age is only partially explained by established cardiovascular disease and frailty.

Activities of Daily Living↗

PubMed1994

Expression, purification, and characterization of recombinant rat placental lactogen-I: a comparison with the native hormone.

Rat placental lactogen-I (rPL-I), a member of the PRL/GH gene family, is produced by giant cells in the early trophoblast. The small amount of early placental tissue has limited the purification of rPL-I from this source. To obtain sufficient material for in vitro studies we have used a rPL-I cDNA to express this protein in Chinese hamster ovary (CHO) cells and in these studies have compared the recombinant protein with the native rPL-I. Using an affinity column composed of monoclonal antibody to rPL-I coupled to Sepharose 4B, we have purified rPL-I from four sources: 1) recombinant rPL-I produced and secreted in rPL-I-transfected CHO cells, 2) nonglycosylated recombinant PL-I produced by adding tunicamycin (10 microM/ml medium) to rPL-I-transfected CHO cells, 3) native rPL-I secreted by rat choriocarcinoma (RCHO) cells, and 4) serum rPL-I isolated from day 12 pregnant rats. Analysis by two-dimensional polyacrylamide gel electrophoresis and Western blotting revealed nine subforms with increasing mol wt [approximately 34 kilodaltons (kDa)] and acidic pI for recombinant rPL-I and RCHO-derived rPL-I. Four major species of lower mol wt (approximately 23 kDa) were evident in the nonglycosylated rPL-I, suggesting additional peptide cleavage sites. Serum rPL-I contained four additional forms of higher mol wt (approximately 37 kDa) and more acidic pI. When analyzed by the Nb2 lymphoma cell bioassay, RCHO rPL-I, serum rPL-I, and nonglycosylated rPL-I were equipotent with ovine and human PRL. Recombinant rPL-I was 1.5-2.0 times as active as ovine PRL in the Nb2 assay. A RIA was established for rPL-I. The variant rPL-Iv, displayed nonparallel displacement of [125I]rPL-I from the antibody. There was no cross-reactivity with other pituitary or placental members of the GH/PRL family. Measurement of serum levels of rPL-I by RIA after the injection of recombinant-rPL-I into adult female Sprague-Dawley rats revealed a half-life of 9 min for the recombinant protein compared to 7.8 min for the choriocarcinoma-derived hormone. In conclusion, we have shown that although CHO cells will glycosylate the recombinant protein differently than normal placental cells, the biological properties of our recombinant rPL-I are similar to those of the native, placenta cell-derived hormone.

Animals↗

PubMed1993

Relation of age, exercise, anthropometric measurements, and diet with glucose and insulin levels in a population aged 70 years and over.

A community-based sample of people > or = 70 years from Mosgiel, New Zealand, was investigated to determine the relation of age, diet, exercise, drugs, and anthropometric measurements with glucose and insulin. From an initial sample of 856 subjects on August 1, 1988, 782 (91.4%) completed the questionnaires and physical examination. Glucose was estimated in 726 subjects and insulin in 607 subjects 2 hours after a standardized meal. In the multivariate analysis for women, glucose was related to age and exercise, and insulin was related to glucose levels, triceps skinfold thickness, and waist/hip ratios. In the multivariate analysis for men, none of the variables was related to glucose levels; insulin levels were related to glucose and waist/hip ratio. Impaired glucose tolerance in women was associated with high body mass index, waist/hip ratio, lower exercise levels, and the taking of thiazide drugs or oral steroids. In men, no significant model to identify those with impaired glucose tolerance could be developed. Glucose and insulin levels in women were related to age and external factors, particularly exercise and anthropometric measurements. In men, external factors were less clearly related to glucose and insulin levels, but this lack of association in men may be due to the smaller number of men in the sample, their younger age, and the narrower range of values found in the men.

Age Factors↗

PubMed1993

Over 80 years and no evidence of coronary heart disease: characteristics of a survivor group.

OBJECTIVE: To determine factors that characterize those 80 years and over free of clinical coronary heart disease (CHD). DESIGN: Cross-sectional intergroup comparison. SETTING: Rural New Zealand town. SUBJECTS: All those 70 years and over registered with the sole health center. Seven hundred eighty-two subjects were seen, a 91.4% response rate. Subjects were divided by World Health Organization cardiovascular questionnaire criteria, history, examination, and coded 12-lead electrocardiogram into four groups: 1) those 70-79 years of age with evidence of CHD; 2) those 80 years and older with evidence of CHD; 3) those 70-79 years of age free of CHD; and 4) those 80 years and older free of clinical CHD. MEASUREMENTS: Mean values and distributions of cholesterol, high-density lipoprotein (HDL) cholesterol, apolipoproteins (apos), triglycerides, insulin, glucose, anthropometric measurements, and psychosocial variables. RESULTS: In the initial analysis of variance there was a significant difference in the mean values among the four groups for body mass index (BMI), HDL cholesterol, apo A1, and triglycerides. Using the Duncan procedure, the mean value of HDL cholesterol in the group 80 years and older with no evidence of clinical CHD was significantly higher than in each of the other groups. The group 80 years and older without clinical CHD had a significantly higher mean value for apo A1 and significantly lower mean values for triglycerides and BMI than the group 70-79 years old with CHD (p < 0.05). Three-factor analysis of variance showed those free of clinical CHD had significantly higher values of HDL cholesterol (P = 0.024) and apo A1 (P = 0.022), and lower values of BMI (P = 0.017) and triglycerides (P = 0.018) compared with those who had CHD after controlling for age and sex. Those 80 years and older had lower values of BMI (P = 0.001) and triglycerides (P = 0.018) than those 70-79 years old after controlling for CHD and sex. The group who were 80 years and older and free of clinical CHD had a significantly narrower distribution of values for insulin (P < 0.001), glucose (P = 0.001), diastolic blood pressure (P = 0.001), BMI (P = 0.001), and waist-hip ratio (P = 0.002) when compared with those 80 years and older with CHD; a significantly narrower distribution of values for insulin (P = 0.024), glucose (P = 0.003), and BMI (P = 0.002) when compared with those 79-79 years old with CHD and a significantly narrower distribution of glucose (P = 0.002) and BMI (P = 0.014) when compared with those 70-79 years old and free of clinical CHD. CONCLUSION: Those 80 years and older who were free of clinical CHD were characterized by differences in lipid and anthropometric values, particularly higher HDL cholesterol and apo A1 levels. Results were also consistent with this survivor group maintaining tighter homeostatic control over a number of variables.

Aged↗

PubMed1993

A factor(s) from a trophoblast cell line increases tyrosine hydroxylase activity in fetal hypothalamic cell cultures.

We previously reported that a factor(s) from rat choriocarcinoma (Rcho-1) cells suppresses circulating PRL levels and increases tyrosine hydroxylase activity in tuberoinfundibular dopaminergic neurons in vivo. The purposes of this study were to determine whether this factor(s) increases tyrosine hydroxylase activity in fetal hypothalamic cells in vitro and to evaluate its chemical nature. The Rcho-1 cells are of placental origin and have the capacity to differentiate into giant cells and produce members of the placental PRL family. MMQ cells, a pituitary cell line that secretes PRL, and HRP-1, a placental cell line that does not produce any known members of the PRL family, were used as control cells. Tyrosine hydroxylase activity was assessed by incubation of hypothalamic cells for 1 h with 100 microM brocresine, an inhibitor of aromatic L-amino acid decarboxylase. Tyrosine hydroxylase activity was increased in a density-dependent manner when Rcho-1, but not HRP-1 or MMQ, cells were cocultured with hypothalamic cells for 24 h. Control and Rcho-1-stimulated tyrosine hydroxylase activities were markedly reduced with 1 mM alpha-methyl-p-tyrosine, a specific inhibitor of tyrosine hydroxylase. Tyrosine hydroxylase activity was not altered when hypothalamic cells were incubated for 24 h with rat PRL or recombinant rat placental lactogen-I, whereas a 24-h stimulation with 100,000 Rcho-1 cells and a 1-h stimulation with 5 mM (Bu)2cAMP increased tyrosine hydroxylase activity 3.7- and 3-fold, respectively. The magnitudes of the increase in tyrosine hydroxylase activity were similar when hypothalamic cells were cocultured with Rcho-1 cells for 1 and 24 h. Acetic acid extracts of Rcho-1, but not HRP-1 or MMQ, cells increased tyrosine hydroxylase activity within 1 h in a concentration-dependent manner. The 3-fold increase in tyrosine hydroxylase activity observed with 500,000 Rcho-1 cell equivalents was markedly reduced with 1 mM alpha-methyl-p-tyrosine. The mol wt range of the tyrosine hydroxylase-activating factor(s) (THAF) was estimated using ultrafiltration membranes. The majority of activity was found in the eluate from a 1,000 mol wt cut-off membrane. THAF activity in Rcho-1 cell extracts was decreased by preincubation with pronase, a nonspecific proteolytic enzyme, suggesting that the factor(s) is a peptide. THAF was resistant to inactivation by trypsin or chymotrypsin pretreatment. However, both enzymes destroyed the ability of pituitary adenylate cyclase-activating peptide, either alone or with Rcho-1 cell extracts, to increase tyrosine hydroxylase activity. Oxidation of Rcho-1 cell extracts with performic acid abolished THAF activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1993

Rat placental lactogen-I binds to the choroid plexus and hypothalamus of the pregnant rat.

Recent findings suggest that placental lactogen has a role in the regulation of hypothalamic function during pregnancy. To explore the mechanisms by which placental hormones may exert effects in the maternal central nervous system, we have examined the binding of rat placental lactogen-I (rPL-I) to brain slices from pregnant rats at mid- and late gestation. The binding of rPL-I to maternal rat brain was compared with that of human GH (hGH). Radiolabelled rPL-I bound specifically to ependymal cells of the choroid plexus in the lateral ventricles and in the roof of the third ventricle. The binding of 125I-labelled rPL-I was inhibited by unlabelled rPL-I, hGH or rat prolactin but not by rat GH, indicating that rPL-I and rat prolactin interact with a common binding site in maternal rat brain. Radiolabelled hGH bound to the choroid plexus and to ependymal cells lining the third ventricle in the region of the arcuate nucleus. In addition, hGH bound specifically to the ventromedial nuclei and to the medial preoptic area of the hypothalamus. The binding of radiolabelled hGH to all brain regions was inhibited by unlabelled rPL-I as well as hGH, indicating that rPL-I competes for lactogenic binding sites in the hypothalamus as well as the choroid plexus of the pregnant rat. These findings suggest potential mechanisms by which placental hormones may exert direct effects on the maternal central nervous system during pregnancy. The precise functions and roles of the PL-I binding sites in maternal choroid plexus and hypothalamus remain to be explored.

Animals↗

PubMed1992

Plasma non-cholesterol sterols in patients with non-insulin dependent diabetes mellitus.

Plasma plant sterol concentrations (an index of cholesterol absorption efficiency) and plasma lathosterol concentration (an index of cholesterol synthesis rate) were measured in 52 patients with non-insulin dependent diabetes mellitus (NIDDM) and 36 non-diabetic controls. Plasma plant sterol concentrations were significantly (P less than 0.01) lower in diabetic patients (campesterol: men -36%, women -48%; betasitosterol: men -35%, women -42%). Fasting serum insulin levels were inversely correlated with plasma plant sterol concentrations in diabetic patients (campesterol: r = -0.347, P = 0.012; betasitosterol: r = -0.345, P = 0.012) and in non-diabetic men (campesterol: r = -0.578, P = 0.039; betasitosterol: r = -0.702, P = 0.008). Serum insulin levels were also correlated significantly with plasma lathosterol concentration in diabetic patients (r = 0.295, P = 0.034). The results of this study suggest that absorption of plant sterols and possibly cholesterol from the diet may be reduced in hyperinsulinemic diabetics.

Adult↗

PubMed1992

Cholesterol metabolism in distance runners.

Faecal steroid excretion, including betasitosterol excretion, whole-body cholesterol synthesis, plasma lipids, and lipoprotein concentrations and habitual diet, were determined in 14 male distance runners and 14 sedentary men. The proportion of cholesterol-derived steroids excreted as bile acids, and the quantity of betasitosterol excreted in the faeces were significantly (P less than 0.05) higher in the runners compared with the sedentary men. Faecal betasitosterol excretion and the proportion of cholesterol-derived steroids excreted as bile acids were correlated significantly in the distance runners and the sedentary men (r = 0.774, n = 28, P less than 0.001). These results suggest that greater dietary intake of plant sterols may contribute to the higher proportion of cholesterol-derived steroids excreted as bile acids in distance runners.

Adult↗

PubMed1991

Plasma noncholesterol sterols in male distance runners and sedentary men.

Plasma lathosterol concentration is taken to be an index of the rate of cholesterol synthesis and plasma concentrations of plant sterols just as campesterol and betasitosterol are taken to be indeces of cholesterol absorption efficiency. These noncholesterol sterols were measured in plasma from 14 male distance runners and 10 sedentary men. Plasma lathosterol concentration was 30% lower (P less than 0.02) and plasma betasitosterol concentration was 33% higher (P less than 0.02) in the runners compared to the sedentary men. Plasma concentrations of lathosterol and plant sterols were inversely and significantly (P less than 0.05) correlated in both the runners and the sedentary men. Plasma plant sterol concentrations were correlated positively and significantly (P less than 0.01) with plasma high density lipoprotein cholesterol (HDL-C) concentrations in the runners and sedentary men combined. These findings suggest that more efficient cholesterol absorption may lead to higher plasma plant sterol concentrations and may contribute to lower cholesterol synthesis rates, reduced concentrations of plasma lathosterol and higher plasma HDL-C concentration in distance runners.

Adult↗

PubMed1991

Use of benzodiazepines in private nursing homes: a drug 'index' as an indicator of quality in nursing home care.

Benzodiazepines have attracted criticism as drugs on which patients can become dependent. This paper examines how widely these drugs were prescribed by GPs to patients in 15 Oxfordshire nursing homes during 1987. About one in three patients was found to have such a prescription. The potential relationship between benzodiazepine prescribing and rate of incidents in the homes did not prove clear-cut, although pointing toward a slight negative correlation. Duration of action of the type of benzodiazepine had relevance. An index of benzodiazepine prescriptions per resident was derivable (the 'benzodiazepine index'). This provided an indicator of quality of care which could be used to compare practice between different nursing homes.

Aged↗

PubMed1991

Fecal bile acid concentration in distance runners.

Fecal bile acid concentration, fecal characteristics, bowel habits and habitual food intake were measured in male distance runners (n = 14) and sedentary men (n = 14). Fecal bile acid concentration was significantly (p less than 0.05) lower and stool weight, frequency of defecation and daily intake of fibre, carbohydrate, and protein were significantly (p less than 0.01) higher in the runners. After adjustment for differences in dietary fibre intake, fecal bile acid concentration was no longer significantly different between the distance runners and the sedentary men, but frequency of defecation remained significantly (p less than 0.05) higher in the runners. This study has identified lower fecal bile acid concentration in distance runners, which was probably due mainly to dilution of colon contents by higher consumption of dietary fibre. These findings may be relevant to the reduced incidence of colon cancer in physically active subjects.

Adult↗