AIMTo investigate whether consumption of an energy drink will acutely impair endothelial function in young healthy adults.METHODSEnergy drinks are being consumed more and more worldwide, and have been associated with ...AIMTo investigate whether consumption of an energy drink will acutely impair endothelial function in young healthy adults.METHODSEnergy drinks are being consumed more and more worldwide, and have been associated with some deaths in adolescents and young adults, especially when consumed while exercising. After fasting and not smoking for at least 8 h prior, eleven medical students (9 males) received an electrocardiogram, blood pressure and pulse check, and underwent baseline testing (BL) of endothelial function using the technique of endothelium-dependent flow mediated dilatation (FMD) with high-resolution ultrasound (according to recommended guidelines of the University of Wisconsin Atherosclerosis Imaging Research Program Core Laboratory). The subjects then drank an energy beverage (EB), a 24-oz can of Monster Energy, and the above was repeated at 90 min after consumption. The relative FMD (%) was calculated as the ratio between the average post-cuff release and the baseline diameter. Each image was checked for quality control, and each artery diameter was measured from the media to media points by two experts, 3 measurements at the QRS complex, repeated on 3 separate beats, and then all were averaged.RESULTSSubjects characteristics averages (given with standard deviations) include: Age 24.5 ± 1.5 years, sex 9 male and 2 female, weight 71.0 ± 9.1 kg, height 176.4 ± 6.0 cm, BMI 22.8 ± 2.7 kg/m<sup>2</sup>. The hemodynamics were as follows, BL vs EB group respectively (mean ± SD): Heart rate 65.2 ± 11.3 vs 68.2 ± 11.8 beats per minute, systolic blood pressure 114.0 ± 10.4 mmHg vs 114.1 ± 10.4 mmHg, diastolic blood pressure 68.8 ± 9.3 mmHg vs 70.6 ± 7.1 mmHg; all were not significantly different. However after drinking the EB, a significantly attenuated peak FMD response was measured (mean ± SD): BL group 5.9% ± 4.6% vs EB group 1.9% ± 2.1%; P = 0.03). Given the increased consumption of energy beverages associated with exercise in young adults, more research is needed.CONCLUSIONEnergy beverage consumption has a negative impact on arterial endothelial function in young healthy adults.展开更多
The validity of the flow-mediated dilation (FMD) test has been doubted due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using a simplified mathematical model based...The validity of the flow-mediated dilation (FMD) test has been doubted due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using a simplified mathematical model based on Poiseuille’s law. Poiseuille’s law assumes that the blood velocity profile is parabolic. The presence of turbulence will violate this assumption. The Reynolds number (RE) is used to define critical values for the transition from laminar to turbulent flow. Between RE values of 2000 and 4000, flow enters a transitional phase where turbulence is possible. Purpose: To determine whether brachial artery blood flow becomes turbulent during reactive hyperemia following forearm ischemia. Methods: Eleven healthy male subjects (25 ± 5 years) were tested. Brachial artery diameters and blood velocities were measured continuously following 2, 4, 6 and 10 minutes ischemia. The peak post-ischemic RE (REpeak) and RE integrated over 40 seconds (RE40) post-ischemia were calculated. Results: There was a significant change in REpeak (F4,7 = 98.573, p = ≤ 0.001) and RE40) (F4,7) = 50.613, p = ≤ 0.001) in response to ischemia. Within-subjects contrasts revealed a significant increase in REpeak and RE40 for each duration of ischemia versus baseline (p = ≤ 0.001). Following 4 minutes of ischemia there was approximately 12 seconds of potentially turbulent flow. Conclusion: Blood flow transitions between laminar and turbulent flow during ischemia-induced reactive hyperemia. This may limit the efficacy of estimating shear stress when using the standard FMD test protocol.展开更多
Background: Many factors can contribute to atherosclerotic-type vascular changes in older individuals or men. Thus, confining the investigation to young women with no clinical evidence of the condition could enhance u...Background: Many factors can contribute to atherosclerotic-type vascular changes in older individuals or men. Thus, confining the investigation to young women with no clinical evidence of the condition could enhance understanding of the early stages of cardiovascular disease. The aim of this study was to determine whether carotid mean/max intima-media thickness (IMT) and brachial flow-mediated dilation (FMD) values, which are well-known event-related indices, are associated with laboratory data and the other vascular indices of atherosclerosis in healthy young women. Methods: Carotid mean/max IMT and brachial FMD were measured in young women with no clinical evidence of atherosclerosis (n = 110;mean age, 39 years) who were instructed not to eat, drink or smoke after 9 PM the evening before testing. All participants also underwent laboratory assessment, including simultaneous measurements of arterial stiffness such as augmentation index (AI), cardioankle vascular index (CAVI) and brachial-ankle pulse wave velocity (baPWV). Results: Mean IMT was signifi-cantly and positively associated with age (p = 0.002), CAVI (p = 0.044), low-density lipoprotein-cholesterol (LDL-C, p = 0.047) and high-sensitive C-reactive protein (hs-CRP, p = 0.002) values but was not related to FMD, AI, baPWV or triglycerides (TG) in the multivariate regression analysis. Similarly, max IMT was positively associated with age (p p = 0.003) and hs-CRP (p = 0.005) values but was not related to FMD, AI, CAVI, baPWV, TG or blood pressure level in the multivariate regression analysis. The association between LDL-C and max IMT was much stronger than that between LDL-C and mean IMT. Brachial FMD was positively associated only with heart rate in the multivariate regression analysis. Conclusions: These results suggest that mean IMT more closely represents the sclerotic aspect of vascular change, whereas max IMT represents the atherotic aspect in healthy young women. Although the relationship between the autonomic nervous system and heart rate is well-known, there may be a complex interaction between the autonomic nervous system and endothelial function.展开更多
Aim: The aim of this study was to determine the effect of training on endothelium-dependent vasodilatation in patients with coronary artery disease (CAD) after revascularization and healthy young men. Background: Impa...Aim: The aim of this study was to determine the effect of training on endothelium-dependent vasodilatation in patients with coronary artery disease (CAD) after revascularization and healthy young men. Background: Impaired endothelial function has been observed in patients with CAD and those with CAD risk factors. Studies have shown that exercise can enhance endothelial function. Methods: This experimental cross-sectional study was conducted on patients with CAD (3 months after CABG and PCI) and students of medical school in 2011. Endothelium dependent dilation of the brachial artery was determined by using high-resolution vascular ultrasonography through flow-mediated vasodilatation (FMD) after induction of ischemia, and the data were analyzed using SPSS, dependent t-test and ANCOVA. Findings: The findings showed that at baseline, FMD was reduced in revascularized patients, when compared with healthy young men, after 8 weeks, and exercise training significantly improved FMD in patients underwent training group [from 4.31 ± 1.45 (SD)% to 6.15 ± 0.773 (SD)%, p p ed unchanged, and even after aerobic training, it did not significantly modify the brachial artery diameter in these groups. Conclusion: Our study demonstrates that endothelial dysfunction persisting in CAD patients after revascularization and aerobic training can improve endothelial function in different vascular beds in CAD patients and healthy young men. This may contribute to the benefit of regular exercise in preventing and restricting cardiovascular disease.展开更多
Background Carotid artery intima-media thickness （CIMT） and brachial artery flow-mediated dilation percentage （FMD%） are common parameters used for detecting subclinical atherosclerosis. This study compared subcli...Background Carotid artery intima-media thickness （CIMT） and brachial artery flow-mediated dilation percentage （FMD%） are common parameters used for detecting subclinical atherosclerosis. This study compared subclinical atherosclerosis of the carotid and brachial arteries in rheumatoid arthritis （RA） patients and healthy controls using high resolution ultrasonography. We also investigated their correlation with clinical factors and the association between FMD% and CIMT.展开更多
Objective:Vascular dilation dysfunction has been linked with risk of cardiovascular disease.This study was undertaken to investigate the relationship between physical activity and vascular dilation function in healthy...Objective:Vascular dilation dysfunction has been linked with risk of cardiovascular disease.This study was undertaken to investigate the relationship between physical activity and vascular dilation function in healthy middle-aged adults to help explaining the effect of physical activity on preventing cardiovascular disease.Method:We recruited 91 healthy middle-aged adults to complete a self-report 7-day physical activity recall questionnaire and an exam of brachial artery flow-mediated dilation(FMD) and Nitroglycerin-mediated dilation(NMD) detected by ultrasound.The relationship between physical activity level(PAL) and FMD and NMD were explored.Result:Physical activity showed a significant and positive relationship with the brachial artery FMD,even after adjustment for possible confounding factors(r=0.363,P<0.01).The group of high physical activity level had the highest FMD.The means of FMD(%) in low,moderate and high PAL groups were respectively 8.70%±3.93%,9.01%±3.22% and 12.38±5.67% with significant difference between individuals of low and high PAL and between moderate and high PAL group(P<0.01).The means of NMD(%) is 25.13%±6.52%,24.38%±5.44% and 29.50%±7.25% respectively(P> 0.05) and there was no significant difference among three groups.There was no positive relation between PAL and FMD in premenopausal females but in men and postmenopausal females.Although individuals of high PAL have the best FMD,the moderate PAL can also retard FMD decrease with ageing.Conclusion:Maintaining high physical activity level can enhance endothelial-dependent vascular dilation,and moderate or high physical activity level can prevent endothelial-dependent vascular dilation declining with aging,which may contribute to decrease risk of cardiovascular disease in healthy middle-aged adults.展开更多
基金Supported by McGovern Medical School,The University of Texas Health Science Center at Houston,7000 Fannin St#1200,Houston,TX 77030,University of Texas,No.130744
文摘AIMTo investigate whether consumption of an energy drink will acutely impair endothelial function in young healthy adults.METHODSEnergy drinks are being consumed more and more worldwide, and have been associated with some deaths in adolescents and young adults, especially when consumed while exercising. After fasting and not smoking for at least 8 h prior, eleven medical students (9 males) received an electrocardiogram, blood pressure and pulse check, and underwent baseline testing (BL) of endothelial function using the technique of endothelium-dependent flow mediated dilatation (FMD) with high-resolution ultrasound (according to recommended guidelines of the University of Wisconsin Atherosclerosis Imaging Research Program Core Laboratory). The subjects then drank an energy beverage (EB), a 24-oz can of Monster Energy, and the above was repeated at 90 min after consumption. The relative FMD (%) was calculated as the ratio between the average post-cuff release and the baseline diameter. Each image was checked for quality control, and each artery diameter was measured from the media to media points by two experts, 3 measurements at the QRS complex, repeated on 3 separate beats, and then all were averaged.RESULTSSubjects characteristics averages (given with standard deviations) include: Age 24.5 ± 1.5 years, sex 9 male and 2 female, weight 71.0 ± 9.1 kg, height 176.4 ± 6.0 cm, BMI 22.8 ± 2.7 kg/m<sup>2</sup>. The hemodynamics were as follows, BL vs EB group respectively (mean ± SD): Heart rate 65.2 ± 11.3 vs 68.2 ± 11.8 beats per minute, systolic blood pressure 114.0 ± 10.4 mmHg vs 114.1 ± 10.4 mmHg, diastolic blood pressure 68.8 ± 9.3 mmHg vs 70.6 ± 7.1 mmHg; all were not significantly different. However after drinking the EB, a significantly attenuated peak FMD response was measured (mean ± SD): BL group 5.9% ± 4.6% vs EB group 1.9% ± 2.1%; P = 0.03). Given the increased consumption of energy beverages associated with exercise in young adults, more research is needed.CONCLUSIONEnergy beverage consumption has a negative impact on arterial endothelial function in young healthy adults.
文摘The validity of the flow-mediated dilation (FMD) test has been doubted due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using a simplified mathematical model based on Poiseuille’s law. Poiseuille’s law assumes that the blood velocity profile is parabolic. The presence of turbulence will violate this assumption. The Reynolds number (RE) is used to define critical values for the transition from laminar to turbulent flow. Between RE values of 2000 and 4000, flow enters a transitional phase where turbulence is possible. Purpose: To determine whether brachial artery blood flow becomes turbulent during reactive hyperemia following forearm ischemia. Methods: Eleven healthy male subjects (25 ± 5 years) were tested. Brachial artery diameters and blood velocities were measured continuously following 2, 4, 6 and 10 minutes ischemia. The peak post-ischemic RE (REpeak) and RE integrated over 40 seconds (RE40) post-ischemia were calculated. Results: There was a significant change in REpeak (F4,7 = 98.573, p = ≤ 0.001) and RE40) (F4,7) = 50.613, p = ≤ 0.001) in response to ischemia. Within-subjects contrasts revealed a significant increase in REpeak and RE40 for each duration of ischemia versus baseline (p = ≤ 0.001). Following 4 minutes of ischemia there was approximately 12 seconds of potentially turbulent flow. Conclusion: Blood flow transitions between laminar and turbulent flow during ischemia-induced reactive hyperemia. This may limit the efficacy of estimating shear stress when using the standard FMD test protocol.
文摘Background: Many factors can contribute to atherosclerotic-type vascular changes in older individuals or men. Thus, confining the investigation to young women with no clinical evidence of the condition could enhance understanding of the early stages of cardiovascular disease. The aim of this study was to determine whether carotid mean/max intima-media thickness (IMT) and brachial flow-mediated dilation (FMD) values, which are well-known event-related indices, are associated with laboratory data and the other vascular indices of atherosclerosis in healthy young women. Methods: Carotid mean/max IMT and brachial FMD were measured in young women with no clinical evidence of atherosclerosis (n = 110;mean age, 39 years) who were instructed not to eat, drink or smoke after 9 PM the evening before testing. All participants also underwent laboratory assessment, including simultaneous measurements of arterial stiffness such as augmentation index (AI), cardioankle vascular index (CAVI) and brachial-ankle pulse wave velocity (baPWV). Results: Mean IMT was signifi-cantly and positively associated with age (p = 0.002), CAVI (p = 0.044), low-density lipoprotein-cholesterol (LDL-C, p = 0.047) and high-sensitive C-reactive protein (hs-CRP, p = 0.002) values but was not related to FMD, AI, baPWV or triglycerides (TG) in the multivariate regression analysis. Similarly, max IMT was positively associated with age (p p = 0.003) and hs-CRP (p = 0.005) values but was not related to FMD, AI, CAVI, baPWV, TG or blood pressure level in the multivariate regression analysis. The association between LDL-C and max IMT was much stronger than that between LDL-C and mean IMT. Brachial FMD was positively associated only with heart rate in the multivariate regression analysis. Conclusions: These results suggest that mean IMT more closely represents the sclerotic aspect of vascular change, whereas max IMT represents the atherotic aspect in healthy young women. Although the relationship between the autonomic nervous system and heart rate is well-known, there may be a complex interaction between the autonomic nervous system and endothelial function.
文摘Aim: The aim of this study was to determine the effect of training on endothelium-dependent vasodilatation in patients with coronary artery disease (CAD) after revascularization and healthy young men. Background: Impaired endothelial function has been observed in patients with CAD and those with CAD risk factors. Studies have shown that exercise can enhance endothelial function. Methods: This experimental cross-sectional study was conducted on patients with CAD (3 months after CABG and PCI) and students of medical school in 2011. Endothelium dependent dilation of the brachial artery was determined by using high-resolution vascular ultrasonography through flow-mediated vasodilatation (FMD) after induction of ischemia, and the data were analyzed using SPSS, dependent t-test and ANCOVA. Findings: The findings showed that at baseline, FMD was reduced in revascularized patients, when compared with healthy young men, after 8 weeks, and exercise training significantly improved FMD in patients underwent training group [from 4.31 ± 1.45 (SD)% to 6.15 ± 0.773 (SD)%, p p ed unchanged, and even after aerobic training, it did not significantly modify the brachial artery diameter in these groups. Conclusion: Our study demonstrates that endothelial dysfunction persisting in CAD patients after revascularization and aerobic training can improve endothelial function in different vascular beds in CAD patients and healthy young men. This may contribute to the benefit of regular exercise in preventing and restricting cardiovascular disease.
文摘Background Carotid artery intima-media thickness （CIMT） and brachial artery flow-mediated dilation percentage （FMD%） are common parameters used for detecting subclinical atherosclerosis. This study compared subclinical atherosclerosis of the carotid and brachial arteries in rheumatoid arthritis （RA） patients and healthy controls using high resolution ultrasonography. We also investigated their correlation with clinical factors and the association between FMD% and CIMT.
文摘Objective:Vascular dilation dysfunction has been linked with risk of cardiovascular disease.This study was undertaken to investigate the relationship between physical activity and vascular dilation function in healthy middle-aged adults to help explaining the effect of physical activity on preventing cardiovascular disease.Method:We recruited 91 healthy middle-aged adults to complete a self-report 7-day physical activity recall questionnaire and an exam of brachial artery flow-mediated dilation(FMD) and Nitroglycerin-mediated dilation(NMD) detected by ultrasound.The relationship between physical activity level(PAL) and FMD and NMD were explored.Result:Physical activity showed a significant and positive relationship with the brachial artery FMD,even after adjustment for possible confounding factors(r=0.363,P<0.01).The group of high physical activity level had the highest FMD.The means of FMD(%) in low,moderate and high PAL groups were respectively 8.70%±3.93%,9.01%±3.22% and 12.38±5.67% with significant difference between individuals of low and high PAL and between moderate and high PAL group(P<0.01).The means of NMD(%) is 25.13%±6.52%,24.38%±5.44% and 29.50%±7.25% respectively(P> 0.05) and there was no significant difference among three groups.There was no positive relation between PAL and FMD in premenopausal females but in men and postmenopausal females.Although individuals of high PAL have the best FMD,the moderate PAL can also retard FMD decrease with ageing.Conclusion:Maintaining high physical activity level can enhance endothelial-dependent vascular dilation,and moderate or high physical activity level can prevent endothelial-dependent vascular dilation declining with aging,which may contribute to decrease risk of cardiovascular disease in healthy middle-aged adults.
