Biomedical subjects

B H McArdle

Publications and source records attributed to B H McArdle.

5 recordsLinked to original sources

PubMed2006

Effect of high-fat meals and fatty acid saturation on postprandial levels of the hormones ghrelin and leptin in healthy men.

OBJECTIVE: Ghrelin and leptin play a role in control of food intake and adiposity but mechanisms regulating these hormones in man are poorly defined and evidence that dietary fats may have adverse effects is inconclusive. We investigated whether high-fat meals, which differed in saturated fatty acid (SFA) content acutely modified these hormones. DESIGN: Randomised, double-blind, crossover trial. A high-fat (HF) test meal (59 +/- 4 g fat; 71% of energy as fat) was given for breakfast on two occasions. Meals comprised either high (approximately 70:30) or low (approximately 55:45) saturated:unsaturated fatty acid (SFA:USFA) ratio. Fasting and postprandial measurements of serum total ghrelin (RIA), leptin (enzyme-linked immunosorbent assay (ELISA)) and insulin (RIA) were made over 6 h. Postprandial measurements were also made at 10 and 24 h following a fat-exclusion lunch, snack and dinner. SUBJECTS: A total of 18 lean, healthy men. RESULTS: There was no significant effect of the fatty meal (time, P > 0.05), nor a differential effect of SFA:USFA ratio (treatment*time, P > 0.05) on ghrelin over 6h. Leptin decreased in response to both HF treatments (time, P < 0.001) but increased SFA content did not further inhibit hormone secretion (treatment*time, P > 0.05). There was no significant correlation between ghrelin or leptin and circulating insulin (P>0.05). CONCLUSION: We conclude that HF diets may adversely effect serum leptin, although the circadian decrease may account in part for this response. Increasing dietary SFAs had no deleterious effects on leptin or total ghrelin.

Adult↗

PubMed2004

Effect of moderate changes in dietary fatty acid profile on postprandial lipaemia, haemostatic and related CVD risk factors in healthy men.

OBJECTIVE: To investigate the effect of moderate changes in dietary fatty acid profile on postprandial risk factors for cardiovascular disease (CVD). DESIGN: Double-blind, randomised, crossover, intervention trial. SETTING: : University of Auckland Human Nutrition Unit, New Zealand. SUBJECTS: A total of 18 lean healthy men. INTERVENTION: A dairy butter fat modified to reduce the saturated:unsaturated fatty acid ratio and a conventional high saturated butter fat were given on two separate occasions as a high-fat test meal (59+/-4 g fat; 71 en% fat) at breakfast. A fat exclusion lunch, dinner and snacks were also given. Blood samples were collected at 0 (baseline), 1, 3, 6, 10 and 24 h. RESULTS: Maximum peak in total triacylglycerol (TAG) occurred 3 h postprandially and was highest on modified treatment (diet, P<0.05) due predominantly to increased TAG within the chylomicron-rich fraction. Transient peaks in total-, LDL- and HDL-cholesterol occurred postprandially, but did not differ between dietary treatments (P>0.05). There were no differential effects of diet on postprandial free fatty acids, apo A, apo B, glucose, insulin, amylin or haemostatic clotting factors (P>0.05). CONCLUSIONS: In a group of healthy young men, replacement of 16% of total saturated fatty acids by mono- and polyunsaturated fats within a dairy lipid did not induce postprandial changes in CVD risk that may be considered beneficial for health. SPONSORSHIP: Fonterra, Wellington; New Zealand.

Butter↗

PubMed2002

Lipid-lowering effects of a modified butter-fat: a controlled intervention trial in healthy men.

OBJECTIVE: To investigate the lipid-lowering potential of a butter-fat modified through manipulations in bovine feeding to increase the unsaturated:saturated fatty acid ratio. DESIGN: Double-blind, randomised, cross-over intervention trial. SETTING: University of Auckland Human Nutrition Unit, New Zealand. SUBJECTS: Twenty healthy, male subjects. INTERVENTION: A residential trial in which all foods and beverages were provided during two intervention periods, comprising 3 weeks of high unsaturated 'modified' vs. 3 weeks of saturated 'control' butter feeding separated by a 4 week washout. Diets were of typical composition of 39 percentage energy (en%) fat (20 en% butter-fat), 48 en% CHO, 13 en% protein. RESULTS: There was a significant decrease in both total (P<0.05, -7.9%) and LDL-cholesterol (P<0.01, -9.5%) during modified butter feeding. There was no significant effect of treatment on a range of other risk factors including HDL-cholesterol, triglyceride, apolipoprotein A or B, nonesterified fatty acids (NEFA), haemostatic clotting factor VII and fibrinogen or glucose (P>0.05). Subjects were maintained in energy balance and there was no significant change in body weight during intervention. Butter-fat composition alone differed between treatments. CONCLUSIONS: A significant improvement in cardiovascular risk can be achieved by moderate changes in dietary fatty acid profile, achieved through a common and well accepted food source, butter-fat.

Analysis of Variance↗

PubMed2002

Pressure in the cuffs of tracheal tubes at altitude.

Pressures in the cuffs of three commonly used tracheal tubes (Portex Profile Softseal, Mallinckrodt Lo-Contour and Mallinckrodt Hi-Contour, size 8.0 mm and 9.0 mm internal diameter), inflated with air, were measured during simulated ascents in an altitude chamber to 10 000 ft. There was no detectable difference in performance between sizes for each type of tracheal tube. When averaged over the two sizes for each type of tube, cuff pressure reached the critical perfusion pressure 50 cmH2O (37 mmHg) for tracheal mucosa at a higher altitude in the Portex Profile Softseal (2837 ft, 95% CI 2488-3186 ft) than in the Mallinckrodt Lo-Contour (2128 ft, 95% CI 1779-2476 ft; p = 0.02) and Mallinckrodt Hi-Contour (1820 ft; 95% CI 1471-2168 ft; p = 0.002) tracheal tubes. When the cuffs of the 9.0-mm tracheal tubes were inflated with saline, much smaller increases in pressure were measured with increasing altitude, although inflation of the cuffs with saline was technically difficult. Commonly used tracheal tubes with air-inflated cuffs can be used for aeromedical retrieval, but air should be evacuated from the cuffs after increases in altitude of as little as 2000-3000 ft.

Aerospace Medicine↗

PubMed1987

The significance of differences between means. A simulation study.

1. Three tests of statistical significance: the confidence interval (C), Student's t, and Satterthwaite's corrected t were compared using a computer generated sampling experiment. 2. The C-test was shown to be extremely inefficient at detecting differences between pairs of means. The t-test performed as expected and Satterthwaite's correct t was slightly conservative. 3. When the population variances are different Satterthwaite's corrected t performed extremely well, the t-test was slightly liberal, while the C-test remained extremely insensitive. 4. It is concluded that the C-test should not be used (i.e. against Scheer, 1986, Comp. Biochem. Physiol. 83A, 405-408). 5. It is noted that when many t-tests are performed on one data set, alternative methods are appropriate.

Biometry↗