Microcirculatory Rarefaction in South Asians — A Potential Mechanism for Increased Cardiovascular Risk and Diabetes

Hughes, Alun D.; Bathula, Raj; Park, Chloe; Tillin, Therese; Wit, Nicholas; Thom, Simon; Chaturvedi, Nish

doi:10.1371/journal.pone.0076680

Cited by 8 publications

(6 citation statements)

References 44 publications

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“…The difference in TSI% between South Asians and Europeans persisted after adjustment for type 2 diabetes or HbA 1c (though significance was lost) and, although the difference was slightly attenuated by adjusting for other mediators alongside V O 2 and type 2 diabetes (age, sex, physical activity level, CVD, WHR, smoking, haemoglobin, hypertension and β-blocker use), the β coefficient for ΔTSI% in South Asians vs Europeans changed by only 0.3, from −0.8 (p = 0.051) to −0.5 (p = 0.274). These data suggest that underlying vascular dysfunction contributes to impaired exercise capacity in South Asians, consistent with previous observations of impaired macro-and microvascular function in South Asian individuals [31,32].…”

Section: Discussionsupporting

confidence: 92%

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults

et al. 2019

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Aims/hypothesis The aim of this study was to compare exercise capacity, strength and skeletal muscle perfusion during exercise, and oxidative capacity between South Asians, African Caribbeans and Europeans, and determine what effect ethnic differences in the prevalence of type 2 diabetes has on these functional outcomes. Methods In total, 708 participants (aged [mean±SD] 73 ± 7 years, 56% male) were recruited from the Southall and Brent Revisited (SABRE) study, a UK population-based cohort comprised of Europeans (n = 311) and South Asian (n = 232) and African Caribbean (n = 165) migrants. Measurements of exercise capacity using a 6 min stepper test (6MST), including measurement of oxygen consumption (V O 2) and grip strength, were performed. Skeletal muscle was assessed using near infrared spectroscopy (NIRS); measures included changes in tissue saturation index (ΔTSI%) with exercise and oxidative capacity (muscle oxygen consumption recovery, represented by a time constant [τ]). Analysis was by multiple linear regression. Results When adjusted for age and sex, in South Asians and African Caribbeans, exercise capacity was reduced compared with Europeans (V O 2 [ml min −1 kg −1 ]: β = −1.2 [95% CI-1.9, −0.4], p = 0.002, and β −1.7 [95% CI-2.5, −0.8], p < 0.001, respectively). South Asians had lower and African Caribbeans had higher strength compared with Europeans (strength [kPa]: β = −9 [95% CI-12, −6), p < 0.001, and β = 6 [95% CI 3, 9], p < 0.001, respectively). South Asians had greater decreases in TSI% and longer τ compared with Europeans (ΔTSI% [%]: β = −0.9 [95% CI-1.7, −0.1), p = 0.024; τ [s]: β = 11 [95% CI 3, 18], p = 0.006). Ethnic differences in V O 2 and grip strength remained despite adjustment for type 2 diabetes or HbA 1c (and fat-free mass for grip strength). However, the differences between Europeans and South Asians were no longer statistically significant after adjustment for other possible mediators or confounders (including physical activity, waist-to-hip ratio, cardiovascular disease or hypertension, smoking, haemoglobin levels or β-blocker use). The difference in ΔTSI% between Europeans and South Asians was marginally attenuated after adjustment for type 2 diabetes or HbA 1c and was also no longer statistically significant after adjusting for other confounders; however, τ remained significantly longer in South Asians vs Europeans despite adjustment for all confounders. Conclusions/interpretation Reduced exercise capacity in South Asians and African Caribbeans is unexplained by higher rates of type 2 diabetes. Poorer exercise tolerance in these populations, and impaired muscle function and perfusion in South Asians, may contribute to the higher morbidity burden of UK ethnic minority groups in older age. Keywords Ethnicity. Exercise capacity. Skeletal muscle. Type 2 diabetes Abbreviations ATT Adipose tissue thickness CVD Cardiovascular disease FFM Fat-free mass Hb diff Difference between the oxygenated and deoxygenated haemoglobin signal 6MST 6 min stepper test MVPA Moderate-to-vigorous physic...

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Section: Discussionsupporting

confidence: 92%

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults

et al. 2019

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“…Capillary or microvascular rarefaction has been noted in other tissues like retina and skin along with kidney and is more prevalent among the South Asian individuals as compared to other population. It has also been proposed as an independent risk factor for diabetes mellitus and cardiovascular diseases like hypertension [ 30 31 32 ]. A larger population based studies with renal perfusion correlation with standardized protocol needs to be conducted to establish the prevalence of capillary rarefaction in kidney and its role in renal cortical elasticity values in Nepalese population.…”

Section: Discussionmentioning

confidence: 99%

Renal Cortical Elastography: Normal Values and Variations

Singh

Panta

Khanal

et al. 2017

Journal of Medical Ultrasound

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IntroductionRenal cortical elastography has shown conflicting but promising results in evaluation of chronic kidney disease and other renal disorders. The purpose of this study was to establish a normogram of renal cortical elasticity values and assess their variation between right and left kidney and their relation with age, gender, body mass index, renal dimensions and skin to cortex distance.MethodsThe study was a hospital based cross sectional study performed at Tribhuvan University Teaching Hospital, a tertiary care center in Kathmandu, Nepal. All individuals referred for Ultrasound from General Health Check up clinic were included in the study. Patient with abnormal ultrasound findings and abnormal renal function test were excluded from the study. Renal morphometry including length, cortical thickness, and skin to cortex distance were measured in B mode imaging and renal cortical elastography was measured with region of interest box of 1 × 0.5 cm. All analyses were done using Statistical Package for Social Sciences 20.0 soft ware.ResultsA total of 95 individuals who met the inclusion criteria were included in the study. The mean values of right and left renal cortical shear wave velocity were 1.49 ± 0.19 m/s and 1.54 ± 0.19 m/s respectively. Statistical significant difference was observed between the renal cortical shear wave velocity of right and left kidney. The renal shear wave velocity was seen to decrease with age, however the correlation was not statistically significant. No significant difference was also noted in renal shear wave velocity among various sex or Body mass index groups. Statistically significant negative correlation was noted between skin to cortex distance and renal cortical shear wave velocities. However no statistically significant correlation was noted between renal dimensions and renal cortical shear wave velocities.ConclusionsThe normal cortical elasticity values in terms of shear wave velocity of right and left kidney were established. Renal elasticity is independent of the age, gender, Body mass index and renal dimensions.

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“…Since, in agreement with previous studies we did not find significant differences in HRV indices between Indians and Caucasians and between Indian and African subjects, 16,23 the differences in the response to slow breathing and blood pressure cannot be attributed to altered autonomic regulation, but possibly might be related to reduced capillary density, or, rarefaction, reported for healthy normotensive individuals of South Asian origin. 24,25 Further study of this population would elucidate this matter.…”

Section: Ethnic/racial Differences In Hemodynamic and Hrv Indicesmentioning

confidence: 97%

Slow breathing has unequal effects on prehypertensives from different ethnic/racial groups

Shekh

2017

Ann Med Physiol.

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In this study, we investigated whether slow breathing reduces blood pressure (BP) in individuals at risk of developing hypertension and if slow breathing has the same effect on Caucasian, African, Arabian and Indian subjects. Also we assessed ethnic/racial differences in low frequency (LF) power and high frequency (HF) power of heart rate variability (HRV). A total of 40 Caucasian men from Ukraine, 39 West African men mostly from Nigeria, 38 Arabic men from Palestine and Israel and 41 South Asian men from India studying at V. N. Karazin Kharkiv National University were recruited in this study. The subjects were further classified into normotensive and prehypertensive groups. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), LF power, HF power of HRV were recorded at spontaneous breathing and at paced breathing of 10 and 6 breaths per minute. It was found that slowing respiratory rate to 6 breaths per minute reduces SBP in prehypertensive Caucasians, Arabs, Indians, but not in Africans. At 6 breaths per minute, natural logarithm of HF (LnHF) power indicating cardiovagal activity was less in normotensive Arabs than in Caucasians, Africans and Indians possibly suggesting an increased risk of developing hypertension; while prehypertensive Africans demonstrated LnHF power higher than Arabs and Indians. When covariates like age and body mass index (BMI) were considered, prehypertensive Africans demonstrated LnHF power higher than in Caucasians also. It is suggested that in prehypertensive Africans the control of autonomic nervous activity is reset to a higher level of parasympathetic outflow.

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Microcirculatory Rarefaction in South Asians — A Potential Mechanism for Increased Cardiovascular Risk and Diabetes

Cited by 8 publications

References 44 publications

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults

Renal Cortical Elastography: Normal Values and Variations

Slow breathing has unequal effects on prehypertensives from different ethnic/racial groups

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