Exercise training enhances endothelial function in young men.
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OBJECTIVES: The present study was designed to assess whether exercise training can enhance endothelium-dependent dilatation in healthy young men. BACKGROUND: Exercise has been shown to reduce cardiovascular morbidity and mortality, but the mechanisms for this benefit are unclear. Endothelial dysfunction is an early event in atherogenesis, and animal studies have shown that exercise training can enhance endothelial function. METHODS: We have examined the effect of a standardized, 10-week, aerobic and anaerobic exercise training program on arterial physiology in 25 healthy male military recruits, aged 17 to 24 (mean 20) years, of average fitness levels. Each subject was studied before starting, and after completing the exercise program. Baseline vascular reactivity was compared with that of 20 matched civilian controls. At each visit, the diameter of the right brachial artery was measured at rest, during reactive hyperemia (increased flow causing endothelium-dependent dilation) and after sublingual glyceryltrinitrate (GTN; an endothelium-independent dilator), using high-resolution external vascular ultrasound. RESULTS: At baseline, flow-mediated dilatation (FMD) and GTN-mediated dilatation were similar in the exercise and control groups (FMD 2.2+/-2.4% and 2.4+/-2.8%, respectively, p = 0.33; GTN 13.4+/-6.2 vs. 16.7+/-5.9, respectively, p = 0.53). In the military recruits, FMD improved from 2.2+/-2.4% to 3.9+/-2.5% (p = 0.01), with no change in the GTN-mediated dilation (13.4+/-6.2% vs. 13.9+/-5.8%, p = 0.31) following the exercise program. CONCLUSION: Exercise training enhances endothelium-dependent dilation in young men of average fitness. This may contribute to the benefit of regular exercise in preventing cardiovascular disease. (+info)
A retrospective study of buprenorphine and norbuprenorphine in human hair after multiple doses.
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The analysis of hair has been proposed as a tool for monitoring drug-treatment compliance. This study was performed to determine if buprenorphine (BPR) and norbuprenorphine (NBPR) could be detected in human hair after controlled administration of drug and to determine if segmental analysis of hair was an accurate record of the dosing history. Subjects with dark hair (six males, six females) received 8 mg sublingual BPR for a maximum of 180 days. Single hair collections were made once after BPR treatment and stored at -20 degrees C until analysis. Hair was aligned scalp-end to tip and then segmented in 3-cm sections. For this study, it was assumed that the mean hair growth rate was 1.0 cm/month. Deuterated internal standard was added to hair segments (2-20 mg of hair) and digested overnight at room temperature with 1 N NaOH. Specimens were extracted with a liquid-liquid procedure and analyzed by liquid chromatography-tandem mass spectrometry. The limits of quantitation for BPR and NBPR were 3 pg/mg and 5 pg/mg, respectively, for 20 mg of hair. BPR and NBPR concentrations were highest for all subjects in hair segments estimated to correspond to the subject's period of drug treatment. With one exception, NBPR was present in higher concentrations in hair than was the parent compound. BPR concentrations in hair segments ranged from 3.1 pg/mg to 123.8 pg/mg. NBPR concentrations ranged from 4.8 pg/mg to 1517.8 pg/mg. In one subject, BPR and NBPR were not detected in any hair segment. In some subjects, BPR and NBPR were detected in hair segments that did not correspond to the period of drug treatment, suggesting that drug movement may have occurred by diffusion in sweat and other mechanisms. The data from this study also indicate that there is a high degree of intersubject variability in measured concentration of BPR and NBPR in hair segments, even when subjects receive the same dose for an equivalent number of treatment days. Future prospective studies involving controlled drug administration will be necessary to evaluate whether hair can serve as an accurate historical record of variations in the pattern of drug use. (+info)
Premedication with melatonin: a double-blind, placebo-controlled comparison with midazolam.
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We have evaluated the perioperative effects of melatonin with those of midazolam in 75 women in a prospective, randomized, double-blind, placebo-controlled study. Patients were given sublingual midazolam 15 mg, melatonin 5 mg or placebo, approximately 100 min before a standard anaesthetic. Sedation, anxiety and orientation were quantified before, and 10, 30, 60 and 90 min after premedication, and 15, 30, 60 and 90 min after admission to the recovery room. Psychomotor performance was evaluated at these times also, using the digit-symbol substitution test (DSST) and the Trieger dot test (TDT). Patients who received premedication with either midazolam or melatonin had a significant decrease in anxiety levels and increase in levels of sedation before operation compared with controls. Midazolam produced the highest scores for sedation at 30 and 60 min after administration and significant psychomotor impairment in the preoperative period compared with melatonin or placebo. After operation, patients who received midazolam or melatonin premedication had increased levels of sedation at 30 min and impairment in performance on the DSST at 15, 30 and 90 min compared with controls. There were no significant differences between the three groups for anxiety levels or TDT performance after operation. Amnesia was notable only in the midazolam group for one preoperative event (entry into the operating room). Patient satisfaction was noted in the midazolam and melatonin groups only. We have demonstrated that melatonin can be used effectively for premedication of adult patients. (+info)
The impact of heavy passive smoking on arterial endothelial function in modernized Chinese.
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OBJECTIVES: The study evaluated whether heavy exposure to environmental tobacco smoke (passive smoking) might damage arterial function in modernized Chinese. BACKGROUND: Heavy passive smoking is associated with arterial endothelial dysfunction in Caucasian, but not rural Chinese, subjects. METHODS: We studied 20 young (mean age 36.6 +/- 7.0 years) nonsmoking asymptomatic casino workers (9 men) in Macau who were exposed to environmental tobacco smoke for over 8 h/day for at least two years and 20 normal subjects (control subjects). These two groups were carefully matched for age, gender, body mass index (BMI), blood pressure, vessel diameter, cholesterol and glucose levels. Brachial artery diameter was measured by high-resolution B-mode ultrasound at rest, after flow increase (causing flow-mediated endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator). RESULTS: Flow-mediated dilation (mean +/- SD% of diameter changes) was significantly lower in passive smokers (6.6 +/- 3.4%) compared with the controls (10.6 +/- 2.3%) (p < 0.0001). Nitroglycerin-induced dilation of the two groups were similar. Upon multivariate analysis, passive smoking exposure was the strongest independent predictor (beta = -0.59; p = 0.0001) for impaired flow-mediated endothelium-dependent dilation (model R2 = 0.75, F value = 6.1, p = 0.0001). CONCLUSIONS: In modernized Chinese, as in Caucasians, exposure to heavy environmental tobacco smoke causes arterial endothelial dysfunction, a key early event in atherosclerosis. This may have serious implications for cardiovascular health in China, currently in a process of rapid modernization. (+info)
Responses to the prolonged head-up tilt followed by sublingual nitrate provocation in asymptomatic older adults.
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BACKGROUND: prolonged head-up tilt testing and sublingual nitrate provocation are increasingly used in the diagnosis of neurocardiogenic syncope. However there are few data regarding the results of these tests in asymptomatic older subjects. OBJECTIVE: to assess the responses to the prolonged head-up tilt test followed by sublingual glyceryl trinitrate provocation in asymptomatic subjects over the age of 60 years. DESIGN: observational study. METHODS: we recruited 64 asymptomatic subjects over the age of 60 (39 men, 25 women) from two general practice lists in Nottingham and Leicester. Exclusion criteria were: history of syncope, ischaemic heart disease, cerebrovascular disease, marked aortic stenosis, carotid artery disease and being unable to stand for the duration of the test. All subjects underwent a full clinical examination, a 12-lead electrocardiogram and a 30-40-min head-up tilt test, during which we monitored the heart rate and blood pressure continuously. We ended the test prematurely if the subjects developed syncope or symptoms of presyncope associated with hypotension with or without bradycardia. If they remained asymptomatic at the end of this period, they received 400 microg of sublingual glyceryl trinitrate and monitoring continued for another 15 min. SETTINGS: two teaching hospitals in Nottingham and Leicester. RESULTS: six (9%) of the subjects had a positive response (syncope or presyncope) to the prolonged head-up tilt test prior to glyceryl trinitrate provocation. After provocation, 30 (52%) of the remaining 58 subjects had a positive response. CONCLUSION: the role of sublingual glyceryl trinitrate provocation following prolonged head-up tilt testing in the diagnosis of neurocardiogenic (vasovagal) syncope in older people is questionable, as many asymptomatic older subjects demonstrate syncopal or presyncopal symptoms. (+info)
Venous pooling during nitrate-stimulated tilt testing in patients with vasovagal syncope.
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AIMS: To investigate the importance of venous pooling and variation in venous tone during nitrate-stimulated tilt testing in patients. METHODS: Ten patients with a history of vasovagal syncope underwent an upright tilt test after an injection of 99mTc-labelled albumin. A gamma camera was positioned at the level of the lower legs. The patients were tilted to 90 degrees for 30 min or until symptoms developed. In those subjects who did not show any symptoms before the end of the 30-min period, isosorbide dinitrate (ISDN) 5 mg was given sublingually and the test was prolonged for a maximum of 15 min. RESULTS: Nine of 10 patients needed nitrate stimulation to develop symptoms, and one patient remained symptom free following ISDN administration. Measurement of radioactivity revealed no significant increase in calf volume after nitrate stimulation (the mean volume increase was 77% before ISDN stimulation and a further 0.9% afterwards). CONCLUSIONS: The higher sensitivity for vasovagal syncope during upright tilt testing after administration of sublingual ISDN is not due to an increase in venous pooling in the lower extremities. (+info)
Relationship between the angiotensin-converting enzyme genotype and the forearm vasodilator response to estrogen replacement therapy in postmenopausal women.
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OBJECTIVES: We sought to evaluate the relationship between the angiotensin-converting enzyme (ACE) genotype and the change in forearm vasoreactivity in response to a three-month course of oral estrogen in postmenopausal women. BACKGROUND: The ACE genotype is a known predictor of the response to an ACE inhibitor drug; however, it is not clear whether it can modify the effect of estrogen replacement therapy (ERT) on endothelial function in postmenopausal women. METHODS: Fifty-five postmenopausal women received 0.625 mg of conjugated equine estrogen daily for three months. Forearm blood flow (FBF) was measured by strain-gauge plethysmography. RESULTS: Twenty-one, 25 and 9 patients had the insertion/deletion (ID), II and DD genotypes, respectively. Plasma ACE activity was significantly higher at baseline in patients with either the DD or ID genotype than in those with the II genotype (p < 0.05). A significant decrease in plasma ACE activity with ERT was seen in the ID and II genotypes (p < 0.05), but not in the DD genotype. There were no significant differences in the FBF responses to reactive hyperemia at baseline between the three groups. Estrogen replacement therapy did not alter the FBF response to reactive hyperemia in the DD genotype (4.0 +/- 1.3%), although ERT significantly increased the FBF response in the ID and II genotypes (32.6 +/- 7.5% and 30.6 +/- 6.5%, respectively; p < 0.05). Forearm blood flow after administration of sublingual nitroglycerin did not change over three months in any of the three groups. CONCLUSIONS: These findings suggest that the effect of ERT in postmenopausal women on forearm endothelial function may be determined in part by the genotype of the ACE gene. (+info)
Evaluation of the method for nifedipine administration for a rapid onset of clinical effect: a clinical study in normal volunteers.
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Nifedipine is frequently used for patients who require an immediate reduction of blood pressure elevated temporarily by various administration techniques including sublingual route without administrating intravenous infusion of vasodilator. A cross-over clinical study was conducted to investigate the optimal administration method of nifedipine for rapid management of hypertension. Four method of administering 10 mg nifedipine (the capsule was bitten and swallowed, sublingually with a hole in it or the contents administered orally or intranasally with a syringe) were evaluated with regarded efficacy, safety, and usefulness in 6 normal volunteers. Systolic and diastolic blood pressures were correlated with the nifedipine serum concentration in each method. Nifedipine pharmacokinetic parameters differed among the 4 administration methods. Nifedipine was absorbed rapidly by not only intestinal mucosa but also the nasal or oral mucosa. The pharmacological effect of intranasal or sublingual administration was superior. However, mint oil which is present in nifedipine capsules stimulates nasal mucosa when administered intranasally. For clinical usage, nifedipine capsules in which a hole is made with a needle, administered sublingually, can be effectively and safely used for rapid management of systemic hypertension. (+info)