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Biomedical subjects

Michael F Wilson

Publications and source records attributed to Michael F Wilson.

7 recordsLinked to original sources
PubMed2006

Cortisol responses to mental stress, exercise, and meals following caffeine intake in men and women.

Caffeine elevates cortisol secretion, and caffeine is often consumed in conjunction with exercise or mental stress. The interactions of caffeine and stress on cortisol secretion have not been explored adequately in women. We measured cortisol levels at eight times on days when healthy men and women consumed caffeine (250 mg x 3) and underwent either mental stress or dynamic exercise protocols, followed by a midday meal, in a double blind, placebo-controlled, crossover design. Men and women had similar cortisol levels at the predrug baselines, but they responded differently to mental stress and exercise. The cortisol response to mental stress was smaller in women than in men (p=.003). Caffeine acted in concert with mental stress to further increase cortisol levels (p=.011), the effect was similar in men and women. Exercise alone did not increase cortisol, but caffeine taken before exercise elevated cortisol in both men and women (ps<.05). After a postexercise meal, the women had a larger cortisol response than the men, and this effect was greater after caffeine (p<.01). Cortisol release in response to stress and caffeine therefore appears to be a function of the type of stressor and the sex of the subject. However, repeated caffeine doses increased cortisol levels across the test day without regard to the sex of the subject or type of stressor employed (p<.00001). Caffeine may elevate cortisol by stimulating the central nervous system in men but may interact with peripheral metabolic mechanisms in women.

Adult↗
PubMed2005

Quality of life in octagenarians after coronary artery bypass grafting.

Efficacy of coronary artery bypass grafting is well accepted, but its role in octogenarians remains unclear. Therefore, quality of life was evaluated in 73 consecutive octogenarians who underwent coronary artery bypass grafting (1996 to 2001) with data collected in terms of age, gender, New York Heart Association status, co-morbidities, and intra- and postoperative complications. Quality of life was evaluated by a standardized questionnaire to assess postoperative outcomes in terms of functional status (Karnofsky scale), morbidity, and mortality.

Activities of Daily Living↗
PubMed2005

Caffeine tolerance is incomplete: persistent blood pressure responses in the ambulatory setting.

BACKGROUND: Caffeine in dietary doses is a well-established pressor agent. Tolerance to this pressor effect occurs in only about half of regular consumers in acute laboratory tests. The clinical significance of this incomplete tolerance depends on whether the pressor effect is maintained throughout the day with repeated intake. Therefore, we examined the ability of a standard dose of caffeine (250 mg x 3) to maintain a blood pressure (BP) elevation during 18 hours of ambulatory BP monitoring (ABPM) after 5 days of regular daily intake of varying background doses. METHODS: Eighty-five men and women completed a four-week double blind, crossover trial. During each week, subjects consumed capsules totaling 0, 300, or 600 mg/day of caffeine in 3 divided doses. On day 6, they consumed capsules with either 0 or 250 mg at 9:00 am and 1:00 pm, in the laboratory, and again at 6:00 pm during ABPM. Tolerance was defined as a reduction in the diastolic BP response to two challenge doses given in the lab in response to increasing daily intake. Data were analyzed using multivariate repeated measures analysis of variance. RESULTS: BP responses to caffeine above those found on placebo-placebo (P-P) week were found for both tolerance groups when caffeine was consumed after a week of receiving a placebo. However, only the low tolerance group showed increases, above those found on P-P week, after 300 mg/day in systolic/diastolic BP during the waking hours (mean +/- standard error of the mean = 2.8 +/- 1.1, P = .01/2.2 +/- 0.9, P = .02) and in systolic BP during sleep (2.3 +/- 1, P = .03). CONCLUSIONS: Persistent elevations in BP occurring on a daily basis in some habitual caffeine consumers may hold clinical significance.

Adult↗
PubMed2004

Blood pressure response to caffeine shows incomplete tolerance after short-term regular consumption.

Caffeine acutely raises blood pressure (BP). The clinical significance of this effect depends on whether BP responses persist in persons who consume caffeine on a daily basis. Accordingly, the ability of caffeine to raise BP after 5 days of regular daily intake was tested in a randomized controlled trial. Individual differences in tolerance formation were then examined. Men (n=49) and women (n=48) completed a double-blind, crossover trial conducted over 4 weeks. During each week, subjects abstained for 5 days from dietary caffeine and instead used capsules totaling 0 mg, 300 mg, and 600 mg of caffeine per day in 3 divided doses. On day 6, in the laboratory, they used capsules with either 0 mg or 250 mg of caffeine at 9:00 am and 1:00 pm. Systolic/diastolic BP increases as a result of 250 mg of caffeine remained significant (P<0.006/0.001) at all levels of previous daily consumption. Individual difference comparisons found that although half the subjects had complete loss of systolic and diastolic BP responses to the challenge doses, the other half showed no loss in BP response, even after using 600 mg of caffeine per day for the previous 5 days (F >7.90, P <0.001). The sexes did not differ in degree of tolerance formation. Daily caffeine consumption failed to eliminate the BP response to repeated challenge doses of caffeine in half of the healthy adults who were tested. Caffeine may therefore cause persistent BP effects in persons who are regular consumers, even when daily intake is at moderately high levels.

Adult↗
PubMed2004

Anti-inflammatory and profibrinolytic effect of insulin in acute ST-segment-elevation myocardial infarction.

BACKGROUND: The clinical benefits of insulin previously observed in acute ST-segment-elevation myocardial infarction (STEMI) may be partially explained by an anti-inflammatory effect. We assessed this potential effect of insulin in STEMI patients treated with fibrinolytics. METHODS AND RESULTS: Thirty-two patients receiving reteplase were randomly assigned infusions of either insulin at 2.5 U/h, dextrose, and potassium (GIK) or normal saline and potassium (C) for 48 hours. Plasma concentrations of high-sensitivity C-reactive protein (CRP), serum amyloid A (SAA), plasminogen activator inhibitor-1 (PAI-1), creatine kinase (CK), and CK-MB were measured at baseline and sequentially for 48 hours. Total p47phox protein in mononuclear cells was measured in a subgroup of 13 subjects. Baseline CRP and SAA were significantly increased (2- to 4-fold) at 24 and 48 hours in each group (P<0.01). However, in the insulin group, there was a significant (P<0.05) attenuation of the absolute rise in concentration of CRP and SAA from baseline. The absolute increase of CRP and SAA was reduced by 40% (CRP) and 50% (SAA) at 24 hours and at 48 hours compared with the control group. The absolute increase in PAI-1 from baseline and the percentage increase in p47phox over 48 hours were significantly (P<0.05) lower in the insulin-treated group. CK-MB peaked earlier and tended to be lower in insulin-treated subjects, especially in patients with inferior MI. CONCLUSIONS: Insulin has an anti-inflammatory and profibrinolytic effect in patients with acute MI. These effects may contribute to the clinical benefits of insulin in STEMI.

Aged↗
PubMedDate not supplied

Caffeine stimulation of cortisol secretion across the waking hours in relation to caffeine intake levels.

OBJECTIVE: Caffeine increases cortisol secretion in people at rest or undergoing mental stress. It is not known whether tolerance develops in this response with daily intake of caffeine in the diet. We therefore tested the cortisol response to caffeine challenge after controlled levels of caffeine intake. METHODS: Men (N = 48) and women (N = 48) completed a double-blind, crossover trial conducted over 4 weeks. On each week, subjects abstained for 5 days from dietary caffeine and instead took capsules totaling 0 mg, 300 mg, and 600 mg/day in 3 divided doses. On day 6, they took capsules with either 0 mg or 250 mg at 9:00 AM, 1:00 PM, and 6:00 PM, and cortisol was sampled from saliva collected at 8 times from 7:30 AM to 7:00 PM. RESULTS: After 5 days of caffeine abstinence, caffeine challenge doses caused a robust increase in cortisol across the test day (p < .0001). In contrast, 5 days of caffeine intake at 300 mg/day and 600 mg/day abolished the cortisol response to the initial 9:00 AM caffeine dose, although cortisol levels were again elevated between 1:00 PM and 7:00 PM (p = .02 to .002) after the second caffeine dose taken at 1:00 PM. Cortisol levels declined to control levels during the evening sampling period. CONCLUSION: Cortisol responses to caffeine are reduced, but not eliminated, in healthy young men and women who consume caffeine on a daily basis.

Adult↗