Dyslipidemia without obesity in indigenous Argentinean children living at high altitude

mTOR in the Development of Hypoxic Pulmonary Hypertension Associated with Cardiometabolic Risk Factors

The pathophysiology of pulmonary hypertension is complex and multifactorial. It is a disease characterized by increased pulmonary vascular resistance at the level due to sustained vasoconstriction and remodeling of the pulmonary arteries, which triggers an increase in the mean pulmonary artery pressure and subsequent right ventricular hypertrophy, which in some cases can cause right heart failure. Hypoxic pulmonary hypertension (HPH) is currently classified into Group 3 of the five different groups of pulmonary hypertensions, which are determined according to the cause of the disease. HPH mainly develops as a product of lung diseases, among the most prevalent causes of obstructive sleep apnea (OSA), chronic obstructive pulmonary disease (COPD), or hypobaric hypoxia due to exposure to high altitudes. Additionally, cardiometabolic risk factors converge on molecular mechanisms involving overactivation of the mammalian target of rapamycin (mTOR), which correspond to a central axis in the development of HPH. The aim of this review is to summarize the role of mTOR in the development of HPH associated with metabolic risk factors and its therapeutic alternatives, which will be discussed in this review.

Epidemic trends of dyslipidemia in young adults: a real-world study including more than 20,000 samples

BACKGROUND

There is an urgent need to learn more about the epidemiological features of dyslipidemia in youth to address the high burden of cardiovascular disease.

METHODS

This experiment was an observational, cross-sectional study. The samples were collected from 22,379 college students at Xinjiang Medical University.

RESULT

The overall prevalence of dyslipidemia was 13.17%, which was significantly higher in men (23%) than in women (7.2%), p < 0.01. Similarly, the prevalence rate of obesity in men (11.4%) was significantly higher than that in women (3.4%). The composition of blood lipids, such as triglyceride (TG), total cholesterol (TC), and low density lipoprotein cholesterol (LDL-C), began to increase gradually from the age of 22 and showed a sharp increase after the age of 30; however, a reverse trend was present in high density lipoprotein cholesterol (HDL-C). In terms of the proportion of dyslipidemia in both men and women, low HDL-C accounted for the largest proportion (74%), followed by elevated TGs (14.5%). The overall distribution of rates of dyslipidemia and excess weight showed a U-shaped trend with increasing age, with the lowest rates seen in the 20-24 age group.

CONCLUSION

Our study sheds light on the epidemiological features of dyslipidemia in young adults and enriches the limited data available on dyslipidemia, providing a reference for the close monitoring and control of risk factors to reduce the occurrence and progression of atherosclerotic cardiovascular disease events.

Prevalence of Dyslipidemia among School-Age Children and Adolescents in Addis Ababa, Ethiopia

Objective Lipid abnormalities during childhood might be associated with a higher risk of atherosclerosis development in adulthood. In Ethiopia, there were no data on this area. The present work was aimed at assessing the lipid profile abnormalities among children and adolescents aged between 5 and 17 years, in Addis Ababa, Ethiopia.

Materials and Methods The present school-based cross-sectional study was done from March 2019 to October 2019 in the capital city, Addis Ababa. A total of 504 students were randomly recruited for this study. The total cholesterol, triglyceride, low-density lipoprotein, and high-density lipoprotein-cholesterol levels were determined using the Cobas c501 automated chemistry analyzer. The prevalence of lipid abnormalities was described in percentages. Bivariate and multivariate analyses were performed, and data with p-value less than 0.05 was considered statistically significant.

Results Dyslipidemia in at least one of the lipid profiles was observed in 322 (63.9%) school children, whereas only one of the participants had an abnormality in all four lipid profile tests. The prevalence of total cholesterol 200 mg/dL or higher, low-density lipoprotein 130 mg/dL or higher, high-density lipoprotein less than 40 mg/dL, and triglycerides 130 mg/dL or higher was in 14 (2.8%), 16 (3.2%), 294 (58.4%), and 46 (19.1%) participants, respectively.

Conclusion In the current work, the majority of the study participants had a normal lipid profile except increased prevalence of a reduced concentration of high-density lipoprotein-cholesterol. The overall prevalence of serum lipid abnormalities was 63.9%. Serum lipid levels did not show significant differences with sex, age, fasting habits, or obesity.

Analysis of Excess Mortality Data at Different Altitudes During the COVID-19 Outbreak in Ecuador

Ortiz-Prado, Esteban, Raul Patricio Fernandez Naranjo, Eduardo Vasconez, Katherine Simbaña-Rivera, Trigomar Correa-Sancho, Alex Lister, Manuel Calvopiña, and Ginés Viscor. Analysis of excess mortality data at different altitudes during the COVID-19 outbreak in Ecuador. High Alt Med Biol. 22:406-416, 2021. Background: It has been speculated that living at high altitude confers some risk reduction in terms of SARS-CoV-2 infection, reduced transmissibility, and arguable lower COVID-19-related mortality. Objective: We aim to determine the number of excess deaths reported in Ecuador during the first year of the COVID-19 pandemic in relation to different altitude categories among 221 cantons in Ecuador, ranging from sea level to 4,300 m above. Methods: A descriptive ecological country-wide analysis of the excess mortality in Ecuador was performed since March 1, 2020, to March 1, 2021. Every canton was categorized as lower (for altitudes 2,500 m or less) or higher (for altitudes >2,500 m) in a first broad classification, as well as in two different classifications: The one proposed by Imray et al. in 2011 (low altitude <1,500 m, moderate altitude 1,500-2,500 m, high altitude 2,500-3,500 m, or very high altitude 3,500-5,500 m) and the one proposed by Bärtsch et al. in 2008 (near sea level 0-500 m, low altitude 500-2,000 m, moderate altitude 2,000-3,000 m, high altitude 3,000-5,500 m, and extreme altitude 5,500 m). A Poisson fitting analysis was used to identify trends on officially recorded all-caused deaths and those attributed to COVID-19. Results: In Ecuador, at least 120,573 deaths were recorded during the first year of the pandemic, from which 42,453 were catalogued as excessive when compared with the past 3 years of averages (2017-2019). The mortality rate at the lower altitude was 301/100,000 people, in comparison to 242/100,000 inhabitants in elevated cantons. Considering the four elevation categories, the highest excess deaths came from towns located at low altitude (324/100,000), in contrast to the moderate altitude (171/100,000), high-altitude (249/100,000), and very high-altitude (153/100,000) groups. Conclusions: This is the first report on COVID-19 excess mortality in a high-altitude range from 0 to 4,300 m above sea level. We found that absolute COVID-19-related excess mortality is lower both in time and in proportion in the cantons located at high and very high altitude when compared with those cantons located at low altitude.

Stroke-Related Mortality at Different Altitudes: A 17-Year Nationwide Population-Based Analysis From Ecuador

Introduction: Worldwide, more than 5.7% of the population reside above 1,500 m of elevation. It has been hypothesized that acute short-term hypoxia exposure could increase the risk of developing a stroke. Studies assessing the effect of altitude on stroke have provided conflicting results, some analyses suggest that long-term chronic exposure could be associated with reduced mortality and lower stroke incidence rates.

Methods: An ecological analysis of all stroke hospital admissions, mortality rates, and disability-adjusted life years in Ecuador was performed from 2001 to 2017. The cases and population at risk were categorized in low (<1,500 m), moderate (1,500–2,500 m), high (2,500–3,500 m), and very high altitude (3,500–5,500 m) according to the place of residence. The derived crude and direct standardized age-sex adjusted mortality and hospital admission rates were calculated.

Results: A total of 38,201 deaths and 75,893 stroke-related hospital admissions were reported. High altitude populations (HAP) had lower stroke mortality in men [OR: 0.91 (0.88–0.95)] and women [OR: 0.83 (0.79–0.86)]. In addition, HAP had a significant lower risk of getting admitted to the hospital when compared with the low altitude group in men [OR: 0.55 (CI 95% 0.54–0.56)] and women [OR: 0.65 (CI 95% 0.64–0.66)].

Conclusion: This is the first epidemiological study that aims to elucidate the association between stroke and altitude using four different elevation ranges. Our findings suggest that living at higher elevations offers a reduction or the risk of dying due to stroke as well as a reduction in the probability of being admitted to the hospital. Nevertheless, this protective factor has a stronger effect between 2,000 and 3,500 m.

Physical growth and body adiposity patterns in children and adolescents at high altitudes in Peru: Proposed percentiles for assessment

OBJECTIVES

This study's purpose was to compare physical growth (PG) patterns of children and adolescents living at high elevations with those of other geographic regions, relate body adiposity indicators, and develop percentile reference tables for assessing physical growth and body adiposity.

METHODS

The sample included 1536 children and adolescents ages 5.0 to 17.9 years from Puno (Peru) located between 3821 and 4349 m above sea level. Weight, height, arm and waist circumferences (WC), and three skinfolds measurements were recorded. Body mass index (BMI) and waist-height Index (WHI) were calculated.

RESULTS

PG patterns for children living at a high altitude reflected similar values for weight, height, and arm circumference (AC) to those of their counterparts living in Puno (Peru) and La Paz (Bolivia). When compared with children living at moderate altitudes in Peru, they showed slightly lower PG values. BMI explained between 41% and 64% of the variance in sum of the skinfolds, while WC explained between 47% and 66%. HWI was not a strong predictor of variation in sum of skinfolds. Percentiles were generated for WC and the sum of skinfolds.

CONCLUSION

Weight, height, and, arm and waist circumference patterns for children and adolescents living at high altitudes were similar to those of La Paz (Bolivia). WC and the sum of the skinfolds were better indicators for analyzing abdominal obesity compared to BMI and WHI. The percentiles proposed may be a useful tool for identifying high risk of developing overweight disorders in pediatric populations living at high altitudes.

The predictive value of anthropometric indices for cardiometabolic risk factors in Chinese children and adolescents: A national multicenter school-based study

Objectives

This study aimed to assess the accuracy of body mass index (BMI) percentile, waist circumference (WC) percentile, waist-height ratio, and waist-hip ratio for identifying cardiometabolic risk factors in Chinese children and adolescents stratified by sex and BMI categories.

Methods

We measured anthropometric indices, fasting plasma glucose, lipid profile and blood pressure for 15698 participants aged 6–17 in a national survey between September and December 2013. The predictive accuracy of anthropometric indices for cardiometabolic risk factors was examined using receiver operating characteristic (ROC) analyses. The DeLong test and Z test were used for the comparisons of areas under ROC curves (AUCs).

Results

The prevalence of impaired fasting glucose, dyslipidemia, hypertension and cluster of risk factors were 2.9%, 27.3%, 10.5% and 5.7% respectively. The four anthropometric indices showed poor to fair discriminatory ability for cardiometabolic risk factors with the AUCs ranging from 0.53–0.72. Each index performed significantly better AUCs for dyslipidemia (0.59–0.63 vs. 0.56–0.59), hypertension (0.62–0.70 vs. 0.55–0.65) and clustered risk factors (0.70–0.73 vs. 0.60–0.64) in boys than that in girls. BMI percentile performed the best accuracy for hypertension in both sexes; WC percentile had the highest AUC for dyslipidemia and BMI percentile and waist-height ratio performed similarly the best AUCs for clustered risk factors in boys while BMI percentile, WC percentile and waist-height ratio performed similar and better AUCs for dyslipidemia and clustered risk factors in girls; whereas waist-hip ratio was consistently the poorest predictor for them regardless of sex. Though the anthropometric indices were more predictive of dyslipidemia, hypertension and clustered risk factors in overweight/obese group compared to their normal BMI peers, the AUCs in overweight/obese group remained in the poor range below 0.70.

Conclusions

Anthropometric indices are not effective screening tools for pediatric cardiometabolic risk factors, even in overweight/obese children.

Prevalence of Dyslipidemia in Students from Han, Uygur, and Kazakh Ethnic Groups in a Medical University in Xinjiang, China

In the present study, we aimed to evaluate the prevalence of dyslipidemia in students from different ethnic groups in Xinjiang. It is an observational, cross-sectional study. The sample of 7096 students aged 21-25 years was randomly selected from the clinic of Xinjiang Medical University. Baseline data, serum concentration of total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and fasting plasma glucose (FPG) were reported. The prevalence of changes in lipid profile according to Body mass index (BMI) in three ethnic groups was calculated. Compared with Han and Uygur students, TC, LDL-C, TG and FPG levels were lower in kazakh sutdents, while HDL-C level was lower in Uygur students. The prevalence of high TC change was higher in Uygur students, and high LDL-C change was higher in Han students. The prevalence of low HDL-C change was higher in Uygur students, and high TG change was lower in Kazakh students. The prevalence of high TC, LDL-C, TG and low HDL-C changes was observed in normal weight, overweight and obesity groups according to the nutritional status by BMI among students of each ethnic group. The present study demonstrated the prevalence of dyslipidemia in students from different ethnic groups, and enriched the limited data on the early prevention and treatment of dyslipidemia and cardiovascular diseases in Xinjiang medical students crowd.

Blood pressure level increase with altitude in three argentinean indigenous communities

Objective

To compare blood pressure (BP) levels in three groups of Argentinean Indigenous schoolchildren from similar ethnic backgrounds but living at three different altitudes.

Methods

A cross-sectional study compared 185 (83 females) children aged 5–14 years from San Antonio de los Cobres (SAC), 3750 m above sea level; 46 (23 females) from Cobres, 3450 m; and 167 (83 females) from Chicoana (CH), 1400 m. Anthropometric and BP measurements were performed.

Results

The prevalence of overweight/obesity was lower in SAC (6.5% [12]) and Cobres (4.3% [2]) than in CH (24% [24]) (BMI > 85 percentile per CDC norms). Systolic BP increased significantly with altitude: (SAC 86 mm Hg, Cobres 77 mm Hg, and CH 69 mm Hg). Similar results were obtained with diastolic BP (SAC 57 mm Hg, Cobres 51 mm Hg, and CH 47 mm Hg) and with median arterial pressure (MAP) (SAC 67 mm Hg, Cobres 60 mm Hg, and CH 55 mm Hg). Multiple linear regression analyses showed that altitude was significantly and independently associated with children's systolic BP (beta 10.56; R² = 0.40), diastolic BP (beta 6.27; R² = 0.25) and MAP (beta 7.69; R² = 0.32); adjusted for age, sex, and BMI.

Conclusions

We found that as altitude increased, BP levels increased significantly in indigenous children from similar backgrounds living permanently at different altitudes.

Activity of Lipoprotein-Associated Enzymes in Indigenous Children Living at Different Altitudes

BACKGROUND

High altitude is associated with hypobaric hypoxia, and metabolic modifications. In particular, alterations to lipoprotein-associated enzymes have been reported under hypoxia.

OBJECTIVE

To determine the association between paraoxonase 1 (PON-1) and Cholesteryl-ester transfer protein (CETP) activities and altitude in two groups of Argentinean Indigenous schoolchildren living at different altitudes.

METHODS

A cross-sectional study compared 151 schoolchildren from San Antonio de los Cobres (SAC), 3,750 m, with 175 schoolchildren from Chicoana (CH), 1,400 m. Anthropometric data, lipids, apolipoprotein (apo) A-I, apo B, plus PON-1 and CETP activities were determined.

RESULTS

The prevalence of overweight/obesity was significantly lower in SAC than in CH. Z- BMI (0.3 vs 0.7), Apo A-I/Apo B (1.67 vs. 1.85) and PON-1 (170 vs. 243 nmol/mL.min) were significantly lower in SAC than in CH, respectively. Total cholesterol (156 vs 144 mg/dL), triglycerides (TG) (119 vs. 94 mg/dL), apo A-I (133 vs. 128 mg/dL), apo B (84 vs. 73 mg/dL), hematocrit (48 vs. 41%), transferrin (295 vs. 260 mg/dL) and CETP (181 vs. 150%/mL.h) were significantly higher in SAC than in CH. There was a significant univariate association between altitude and transferrin (r0.38), hematocrit (r0.75), TG (r0.24), apo B (r0.29), PON-1 (r-0.40), and CETP (r0.37). Multiple linear regression analyses showed that altitude was significantly associated with children's TG (β = 0.28, R² = 0.14), HDL-C (β = ‒0.27; R² = 0.23), apo B (β = 0.32; R² = 0.14), CETP (β = 0.38; R² = 0.15) and PON-1 (β = ‒0.36; R² = 0.16), adjusted for age, gender and BMI.

CONCLUSION

SAC children presented a more atherogenic lipid profile, plus lower PON1 and higher CETP activities, than CH children.

The increase in hemoglobin concentration with altitude varies among human populations

Decreased oxygen availability at high altitude requires physiological adjustments allowing for adequate tissue oxygenation. One such mechanism is a slow increase in the hemoglobin concentration ([Hb]) resulting in elevated [Hb] in high-altitude residents. Diagnosis of anemia at different altitudes requires reference values for [Hb]. Our aim was to establish such values based on published data of residents living at different altitudes by applying meta-analysis and multiple regressions. Results show that [Hb] is increased in all high-altitude residents. However, the magnitude of increase varies among the regions analyzed and among ethnic groups within a region. The highest increase was found in residents of the Andes (1 g/dL/1000 m), but this increment was smaller in all other regions of the world (0.6 g/dL/1000 m). While sufficient data exist for adult males and females showing that sex differences in [Hb] persist with altitude, data for infants, children, and pregnant women are incomplete preventing such analyses. Because WHO reference values were originally based on [Hb] of South American people, we conclude that individual reference values have to be defined for ethnic groups to reliably diagnose anemia and erythrocytosis in high-altitude residents. Future studies need to test their applicability for children of different ages and pregnant women.

Regulation of Serum Sphingolipids in Andean Children Born and Living at High Altitude (3775 m)

Recent studies on Andean children indicate a prevalence of dyslipidemia and hypertension compared to dwellers at lower altitudes, suggesting that despite similar food intake and daily activities, they undergo different metabolic adaptations. In the present study, the sphingolipid pattern was investigated in serum of 7 underweight (UW), 30 normal weight (NW), 13 overweight (OW), and 9 obese (O) Andean children by liquid chromatography-mass spectrometry (LC-MS). Results indicate that levels of Ceramides (Cers) and sphingomyelins (SMs) correlate positively with biochemical parameters (except for Cers and Vitamin D, which correlate negatively), whereas sphingosine-1-phosphate (S1P) correlates negatively. Correlation results and LC-MS data identify the axis high density lipoprotein-cholesterol (HDL-C), Cers, and S1P as related to hypoxia adaptation. Specifically UW children are characterized by increased levels of S1P compared to O and lower levels of Cers compared to NW children. Furthermore, O children show lower levels of S1P and similar levels of Cers and SMs as NW. In conclusion, our results indicate that S1P is the primary target of hypoxia adaptation in Andean children, and its levels are associated with hypoxia tolerance. Furthermore, S1P can act as marker of increased risk of metabolic syndrome and cardiac dysfunction in young Andeans living at altitude.

Differential regulation of the unfolded protein response in outbred deer mice and susceptibility to metabolic disease

Endoplasmic reticulum (ER) stress has been causatively linked to the onset of various pathologies. However, whether and how inherent variations in the resulting unfolded protein response (UPR) affect predisposition to ER-stress-associated metabolic conditions remains to be established. By using genetically diverse deer mice (Peromyscus maniculatus) as a model, we show that the profile of tunicamycin-induced UPR in fibroblasts isolated at puberty varies between individuals and predicts deregulation of lipid metabolism and diet-induced hepatic steatosis later in life. Among the different UPR targets tested, CHOP (also known as Ddit3) more consistently predicted elevated plasma cholesterol and hepatic steatosis. Compared with baseline levels or inducibility, the maximal intensity of the UPR following stimulation best predicts the onset of pathology. Differences in the expression profile of the UPR recorded in cells from different populations of deer mice correlate with the varying response to ER stress in altitude adaptation. Our data suggest that the response to ER stress in cultured cells varies among individuals, and its profile early in life might predict the onset of ER-stress-associated disease in the elderly.

This article has an associated First Person interview with the first author of the paper.

Summary: By using genetically diverse deer mice, we show that the expression of different chaperones is highly coordinated in individual animals and its profile predicts the onset of metabolic pathology.

Vitamin D Levels and Cardiometabolic Markers in Indigenous Argentinean Children Living at Different Altitudes

The objective of this study was to assess the association between vitamin D and cardiometabolic markers in 2 indigenous communities from similar ethnic backgrounds, but living at different altitudes. A cross-sectional study compared 152 (72 females) indigenous schoolchildren from San Antonio de los Cobres (SAC), 3750 m above sea level, with 175 (86 females) from Chicoana (CH), 1400 m above sea level, mean age 9 years. Anthropometry, blood pressure, lipids, glucose, insulin, and vitamin D were assessed in spring season. The prevalence of children’s overweight/obesity was significantly lower in SAC, 9.2% (13), than in CH, 41.5% (71). There was a significantly higher prevalence of vitamin D deficiency (<20 ng/mL) in SAC (n = 103, 67.7%) than in CH (n = 62, 36.3%). SAC showed an inverse correlation between vitamin D and insulinemia (r = −0.17, P < .05), whereas CH showed an inverse correlation between vitamin D and systolic blood pressure (r = −0.19, P < .05), z-BMI (body mass index; r = −0.25, P < .01), triglycerides (r = −0.15, P < .05), glucose (r = −0.35, P < .05), and insulinemia (r = −0.24, P < .01). Multiple linear regression analysis showed that vitamin D (β = −.47; R² = .21) was significantly associated with SAC location, adjusted for confounding variables. Vitamin D levels were significantly and directly associated with altitude and inversely with metabolic markers, suggesting that populations living at high altitudes are at higher risk for future cardiovascular diseases.

Blood pressure levels among Indigenous children living at different altitudes

The objective was to compare blood pressure (BP) levels in 2 groups of Indigenous Argentine school children from similar ethnic backgrounds but living at different altitudes. One hundred and fifty-two (46.3%) children (age, 4-14 years) from San Antonio de los Cobres (SAC), at 3750 m above sea level, and 176 children (53.7%) from Chicoana (CH), at 1400 m above sea level, participated in this cross-sectional study. Data for children's anthropometry, BP, glucose, lipids, vitamin D, and insulin, as well as mothers' height and weight were assessed. Hypertension was defined as BP ≥ 95th percentile. The prevalence of overweight/obesity among children was significantly lower in SAC (n = 17, 11.2%) than in CH (n = 74, 42%) (body mass index (BMI) > 85th percentile per US Centers for Disease Control and Prevention norms). However, the prevalence of hypertension was significantly higher among children in SAC (n = 15, 9.9%) than among those in CH (n = 2, 1.1%). Children were divided into 4 groups by mean arterial BP quartiles for comparison by ANOVA. As mean arterial BP increased, age, BMI, glucose, triglycerides, triglycerides/high-density lipoprotein cholesterol, and insulin levels increased significantly. Multiple linear regression analyses showed that children's mean arterial BP was significantly associated with altitude adjusted for confounding variables (R² = 0.42). Furthermore, when mean arterial BP was replaced by systolic BP (R² = 0.51) or diastolic BP (R² = 0.33), similar results were obtained. Our results suggest that Indigenous children who live permanently at high altitude have higher levels of BP, adjusted for confounding variables. Routine BP measurements conducted in the SAC community could be essential for the prevention of cardiovascular disease.

Type 2 diabetes markers in indigenous Argentinean children living at different altitudes

BACKGROUND

Exposure to hypoxia at high altitude is increasingly being recognized as a risk factor for metabolic diseases.

OBJECTIVE

To determine the association between Type 2 diabetes (T2D) risk factors and altitude in two groups of Argentinean indigenous schoolchildren who live permanently at different altitudes.

METHODS

This cross-sectional study compared 142 schoolchildren from San Antonio de los Cobres (SAC), 3750 m above sea level, with 171 from Chicoana (CH), 1400 m. Data for children's anthropometry, blood pressure and lipids, as well as mothers' height and weight were assessed.

RESULTS

There was not a significant difference in age between SAC (9.0 + 2y) and CH (9.4 + 2y) children. However, mean children's weight (29 vs. 38 kg), height (130 vs. 138 cm), BMI (17 vs. 19 kg/m2), and HDL-C (46 vs. 48 mg/dL) were significantly lower in SAC than in CH, respectively. In contrast, systolic blood pressure (87 vs. 70 mmHg), cholesterol (157 vs. 148 mg/dL), and triglycerides (104 vs. 88 mg/dL) were significantly higher in SAC than in CH, respectively. There was not a significant difference in age (33.2 + 7y vs. 34.4 + 8y) and BMI (26.2 + 4y vs. 28 + 5y) between SAC and CH mothers. Multiple linear regression analyses showed that children's blood pressure (R2 = 0.38), triglycerides (R2 = 0.21), and HDL-C (R2 = 0.16) were significantly associated with altitude, adjusted for confounding variables.

CONCLUSION

This study shows that indigenous Argentinean children living at 3750 meters have higher T2D risk compared with those living at 1400 meters above sea level.

Activity of the antioxidant enzyme paraoxonase in Argentinean children living at high altitude

Background: Children living at high altitude in San Antonio de los Cobres (SAC), Argentina, were shown to have lower high-density lipoprotein cholesterol (HDL-C) levels than Buenos Aires (BA) children. HDL antioxidant capacity is mainly attributed to paraoxonase1 (PON1).

Objective: To compare PON1 activity in indigenous SAC vs. BA children.

Methods: A cross-sectional study compared 158 SAC vs. 97 BA children (6–16 years). Anthropometric data and lipoprotein profile were measured. PON1 was evaluated employing paraoxon (PON) and phenylacetate (ARE) activity.

Results: The prevalence of overweight/obesity was lower in SAC than in BA children (18.3 vs. 30.9%). Triglycerides (1.34 vs. 0.90 mmol/l), apo B (0.84 vs.0.72 g/l), apo A-I (1.33 vs. 1.27 g/l), and ARE activity (100 vs. 90 µmol/ml/min) were higher, while HDL-C (1.16 vs. 1.32 mmol/l) and PON activity (170 vs. 203 nmol/ml/min) were lower in SAC than in BA. Separate multiple linear regression analyses showed that SAC children had significantly higher triglyceride (Beta −0.38), apo B (Beta −0.34), and ARE (Beta −0.36) plus lower HDL-C (Beta 0.33) and PON (Beta 0.25) compared with BA; adjusted for age, gender, and BMI.

Conclusion: SAC showed an unfavorable lipoprotein profile, lower PON and higher ARE activities compared with BA children, suggesting the presence of altered HDL metabolism and antioxidant capacity.

Comparison Between HDL-C Levels in Argentine Indigenous Children Living at High Altitudes and U.S. Children

BACKGROUND

Studies have shown low levels of high-density lipoprotein cholesterol (HDL-C) in indigenous children versus urban children from Argentina. We hypothesized that indigenous children living at high altitudes might have lower HDL-C levels compared with U.S. children, probably due to ambient hypoxia, lifestyle conditions, or ethnicity. This study was designed (1) to compare HDL-C levels in Argentinean indigenous children with those reported in the 2011-2012 National Health and Nutrition Examination Survey (NHANES) for U.S. children and (2) to determine the association between HDL-C and adiposity in both groups.

SUBJECTS AND METHODS

A cross-sectional study of 1,232 (631 females) Argentinean indigenous schoolchildren (4-14 years old) from San Antonio de los Cobres (SAC) was performed between November 2011 and November 2014. Anthropometric measures were performed in the whole group and compared with those of 2,151 U.S. children (1,034 females). However, HDL-C concentrations were measured in 905 SAC children and compared with those of 1,451 U.S. children. Analyses were done incorporating sampling weights for age in both samples to obtain unbiased estimates. In the case of NHANES the weights provided by each individual in the 2011-2012 NHANES demographic file were used, whereas in the SAC sample the weights were obtained using the census data provided by the 2010 National Statistics and Censuses Institute of Argentina.

RESULTS

The prevalence of overweight/obesity was significantly lower in SAC (135/1,232; 11%) than in the United States (759/2,151; 35%). However, the prevalence of low levels of HDL-C was significantly higher in SAC (298/905; 33%) than in the United States (142/1,451; 10%). The prevalence of low levels of HDL-C increased significantly in both groups as body mass index categories increased. Multiple logistic regression analysis showed that SAC children had nine and a half times the odds of having low levels of HDL-C compared with U.S. children, adjusted for confounding variables (odds ratio = 9.55; 95% confidence interval, 7.18-12.71).

CONCLUSIONS

This study shows a high prevalence of low levels of HDL-C in indigenous Argentinean children 4-14 years of age living at high altitudes compared with U.S. children.

Cardiometabolic risk factors in native populations living at high altitudes

BACKGROUND

It is generally accepted that metabolic changes that take place in individuals exposed to high elevation are because of ambient hypoxia, which occurs as a consequence of a low total atmospheric pressure. The discovery of hypoxia inducible factor 1 (HIF1), a transcription factor, has been a breakthrough in the understanding of adaption to high altitudes.

OBJECTIVE

The purpose of the present review was to discuss specific epidemiological aspects of cardiovascular disease (CVD) risk factors and their mechanisms in vulnerable, understudied populations living at high altitudes.

RESULTS

Obesity prevalence has been inversely associated with elevation. HIF1 has been related to plasma leptin--a hormone secreted by adipose tissue that produces negative feedback on appetite--and inversely associated with obesity. Diverse factors, such as genetics, chronic hypoxia, diet and lifestyle behaviours, could have an influence on the high dyslipidaemia rates of high-altitude natives. Hypoxia could mediate the effects of altitude on human physiology, including lipid metabolism. Genetic studies suggest that dyslipidaemia could be related to the HIF1. Hypoxia inhibits oxidative phosphorylation and stimulates the oxygen signalling pathway through the HIF1. Low fasting glycaemia in individuals at high altitudes has been shown. An increased GLUT4 protein content in skeletal muscle in response to hypoxia has been reported and could be associated with lower glucose levels. Given the high prevalence of dyslipidaemia and the low prevalence of obesity and diabetes in these impoverished high-altitude communities, changes in lifestyle including decreased physical activity and the consumption of a more westernised diet would likely increase the prevalence of CVD related mortality.

CONCLUSIONS

Control over major CVD risk factors, when identified early, could be the key to reducing morbidity and mortality in patients with limited access to medical services such as Native populations.

Waist Circumference Percentiles in Indigenous Argentinean School Children Living at High Altitudes

BACKGROUND

Central obesity is associated with increased risk of type 2 diabetes.

OBJECTIVES

The study objectives were to develop waist circumference (WC) percentiles, to determine if WC is associated with metabolic risk, and to compare our WC percentiles with those reported in the 2007-2010 National Health and Nutrition Examination Survey (NHANES).

METHODS

A cross-sectional study of 1232 children (606 boys ) 5-14 years was performed from 2011 to 2014 in indigenous Koya children from northwestern Argentina. Anthropometric characteristics, glucose, lipids, and insulin levels were measured. Sex-specific reference percentiles were computed using the Lambda-Mu-Sigma (LMS) method. We obtained 2007-2010 NHANES data for comparison with our results.

RESULTS

Compared with the NHANES 90th percentile, WC values for children in this study were lower by an average of 11.05 cm for girls and 12.66 cm for boys. The prevalence of low high-density lipoprotein cholesterol (HDL-C) was 11.8% in children with WC ≤50th percentile, 10.3% in children with WC >50th-70th percentile, 17.5% in children with WC >70th-90th percentile, and 21.3% in children with WC >90th percentile. The prevalence of high triglycerides (TG) was 19.5% in children with WC ≤50th percentile, 19.9% in children with WC >50th-70th percentile, 28.8% in children with WC >70th-90th percentile, and 39.7% in children with WC >90th percentile. Multiple logistic regression analyses showed that high TG values (>150 mg/dL) were significantly associated with WC [odds ratio (OR)] 1.05; 95% confidence interval (CI) 1.03-1.08; and low HDL-C values (<35 mg/dL) were significantly associated with WC (OR 1.04; 95% CI 1.01-1.06), adjusted for age and gender.

CONCLUSION

We present for the first time WC reference data for indigenous Koya children ages 5-14 years. There was a significant association between WC and dyslipidemia in this community. Compared with the NHANES WC percentiles, our WC values were lower. These differences possibly reflect ethnicity or the lower prevalence of obesity.

Association between triglyceride to HDL-C ratio and insulin resistance in indigenous Argentinean children

BACKGROUND

Insulin resistance is considered one of the major risk factors for the development of type 2 diabetes mellitus (T2DM). Thus, early identification, preferably by using simple and inexpensive diagnostic tools, is essential for preventing T2DM. Triglyceride (TG) to high-density lipoprotein cholesterol (HDL-C) ratio (TG/HDL-C) has been proposed as an inexpensive tool to identify individuals at high risk of T2DM. The objective of this study was to determine the relationship between insulin resistance and TG/HDL-C in indigenous Argentinean children.

METHODS

A cross-sectional study of 501 (243 boys) indigenous school children aged 10.0 ± 2.4 yr were assessed for anthropometry, lipids, glucose, and insulin levels from November 2011 to November 2013. Insulin resistance was defined as the upper third quartile of homeostasis model assessment (HOMA-IR).

RESULTS

The prevalence of overweight/obesity was 11.4% per Centers for Disease Control. Mean levels of various characteristics were: body mass index (BMI) 17.2 ± 2.6, HDL-C 39 ± 9 mg/dL, TGs 121 ± 58 mg/dL, TG/HDL-C 2.9 ± 1.8, glucose 77 ± 8 mg/dL, HOMA-IR 1.0 ± 0.8, and insulin 44 ± 9 mUI/L. Children in the higher quartiles of TG/HDL-C had significantly higher HOMA-IR values than children in the lower quartiles. Multiple linear regression analysis showed that TG/HDL-C was significantly associated with HOMA-IR (r² = 0.19) adjusted for age, gender, and BMI. Furthermore, for a 1-unit increase in log TG/HDL-C, the odds of being insulin resistant (HOMA-IR>III quartile) increased by 2.58 times [odds ratio (OR), 2.58 (1.63-4.05); p < 0.01], adjusted for age, gender, and BMI.

CONCLUSION

This study suggests that TG/HDL-C may be a good marker to identify insulin resistant indigenous Argentinean children.

Altitude and cold weather: are they vascular risks?

PURPOSE OF REVIEW

The relationship of altitude and cold to cardiovascular risk is complex. Cold is hard to separate from altitude. This review highlights the latest information on cardiovascular disease associated with high altitude and cold; both represent unique clinical situations.

RECENT FINDINGS

Evolution and genetics are relevant to high altitude, with much new information available. Specific physiology explains some congenital heart disease at altitude. New reports of hematological changes associated with altitude and cold help clarify thrombosis, which is relevant to reports of very late in-stent thrombosis at altitude. Multiple cardiovascular risk factors are affected by altitude and cold, and an increased incidence of myocardial infarction occurs. There is new research on acute mountain sickness associated with inflammation with relevance for clinical study of pulmonary edema. Socioeconomics plays a part in altitude and cold effects on cardiovascular disease. In addition to acute disease, high altitude involves chronic mountain sickness with new knowledge of associated cardiovascular endothelial abnormalities.

SUMMARY

High altitude and cold involve acute disease, chronic disease, and public health issues. Continued research is essential to enable the best clinical management in this era of rapid worldwide travel.

Glucose homeostasis during short-term and prolonged exposure to high altitudes

Most of the literature related to high altitude medicine is devoted to the short-term effects of high-altitude exposure on human physiology. However, long-term effects of living at high altitudes may be more important in relation to human disease because more than 400 million people worldwide reside above 1500 m. Interestingly, individuals living at higher altitudes have a lower fasting glycemia and better glucose tolerance compared with those who live near sea level. There is also emerging evidence of the lower prevalence of both obesity and diabetes at higher altitudes. The mechanisms underlying improved glucose control at higher altitudes remain unclear. In this review, we present the most current evidence about glucose homeostasis in residents living above 1500 m and discuss possible mechanisms that could explain the lower fasting glycemia and lower prevalence of obesity and diabetes in this population. Understanding the mechanisms that regulate and maintain the lower fasting glycemia in individuals who live at higher altitudes could lead to new therapeutics for impaired glucose homeostasis.

Improvement in high-density lipoprotein cholesterol levels in argentine Indian school children after vitamin D supplementation

BACKGROUND/AIMS

Low vitamin D levels correlate with dyslipidemia, but limited data exist on indigenous children. The objective was to determine whether vitamin D supplementation improves high-density lipoprotein cholesterol (HDL-C) levels among Koya children.

METHODS

A prospective 1-year study evaluated a treated cohort of 70 (38 males) children aged 10.3 ± 2.1 years who received 5,000 U of vitamin D weekly during 8 weeks, and a control group of 20 (8 males) children aged 9.2 ± 1.1 years who did not receive vitamin D.

RESULTS/CONCLUSIONS

At baseline, 18 (20%) had severe vitamin D deficiency (<10 ng/ml), 66 (73.3%) had deficiency (10 to <20 ng/ml), and 6 (6.6%) had insufficiency (20 to <30 ng/ml). At baseline, there was no significant difference in the prevalence of hypovitaminosis D between groups. After 1 year, the prevalence of severe vitamin D deficiency decreased from 20 to 0%, and that of insufficiency increased from 6 to 19% (p < 0.001) only in the treated group. The prevalence of low HDL-C also decreased in the treated group only (35.7-5.7%; p < 0.01). Multiple linear regression analysis showed that treated children improved HDL-C levels by 4 mg/dl (R(2): 0.13) adjusted for confounding factors, suggesting that vitamin D supplementation among Indian children improved HDL-C levels.

Association between nontraditional risk factors and metabolic syndrome in indigenous Argentinean schoolchildren

BACKGROUND

Whether apolipoproteins (Apos) are better cardiovascular disease (CVD) markers than metabolic syndrome (MS) is widely debated. Measurement of Apo B is standardized, simple, and inexpensive and does not require fasting. The aim of this study was to compare the ability of nontraditional CVD markers such as Apo B, Apo B/Apo A, non-high-density lipoprotein cholesterol (HDL-C), vitamin D, and homeostasis model assessment of insulin resistance (HOMA-IR) to identify children with MS.

SUBJECTS AND METHODS

A cross-sectional study of 355 Argentinean Koya schoolchildren (166 boys) 9.6±2.3 years old was performed in November 2011. Anthropometric measures, blood pressure, Tanner stages, and serum levels of glucose, lipids, insulin, Apo A, Apo B, and vitamin D were measured.

RESULTS

The prevalence of overweight/obesity was 10.7% (n=38), and that of underweight was 14.6% (n=52) using Centers for Disease Control and Prevention criteria. The prevalence of central obesity was 10.9% (38/355), high triglycerides was 11.1% (39/355), low HDL-C was 44.9% (158/355), hypertension was 12.8% (45/355), hyperglycemia was 0.3% (1/355), and MS was 4.2% (15/355). Several multiple logistic regression analyses showed that MS was significantly associated with HOMA-IR (odds ratio [OR], 3.6 [95% confidence interval (CI) 1.51-8.52]), non-HDL-C (OR, 1.03 [95% CI 1.007-1.049]), Apo B (OR, 1.06 [95% CI 1.03-1.09]), and Apo B/Apo A (OR, 78.3 [95% CI 3.67-1,674.4]) adjusted for age and gender. Furthermore, the areas under the receiver operator characteristic curves were as follows: Apo B, 0.77 (95% CI 0.63-0.90); Apo B/Apo A, 0.76 (95% CI 0.63-0.88); non-HDL-C, 0.72 (95% CI 0.57-0.85); and HOMA-IR, 0.69 (95% CI 0.49-0.90). These values indicate that these variables were acceptable predictors for MS.

CONCLUSIONS

This is the first study of nontraditional markers in South American Indian children. MS was associated with multiple nontraditional markers of future CVD risk such as non-HDL-C, Apo B, and Apo B/Apo A. However, Apo B was the best predictor for MS, suggesting that it could be used as a risk marker of future CVD in this community.

Association between vitamin D and Apo B concentrations in Argentinean Indian children

OBJECTIVE

The objective of the study was to determine the prevalence of vitamin D insufficiency and its association with non-traditional cardiovascular disease (CVD) risk factors such as Apo B in South American Indian school children.

METHODS

A cross-sectional study of 355 children (166 Males) aged 9.6±2.3 y was performed. Anthropometric measures, glucose, lipids, insulin, Apo B, Apo A, and vitamin D concentrations were measured.

RESULTS

The prevalence of overweight and obesity was 10.7% (38) per CDC. One child (0.3%) had optimal vitamin D concentrations [25(OH)D[>30 ng/ml. Univariate analysis showed significant associations between vitamin D and HDL-C (r=0.12 p<0.05), age (r=-0.11 p<0.05) BMI (r=-0.22 p<0.05), LDL-C (r=-0.22 p<0.01), triglycerides (r=-0.16 p<0.01), non HDL-C (r=-0.21 p<0.01), Apo B (r=-0.23 p<0.01), Apo B/Apo A (r=-0.21 p<0.01), insulin (r=-0.17 p<0.05), and HOMA-IR (r=-0.16 p<0.05). Multiple linear regression analysis showed that female gender and Apo B were significantly associated with vitamin D adjusted for confounding factors (R(2) 0.12).

CONCLUSION

Vitamin D deficiency was associated with increased Apo B among Indian children, suggesting that it could be used as a risk marker of CVD.

Cardiovascular medicine at high altitude

Altitude physiology began with Paul Bert in 1878. Chronic mountain sickness (CMS) was defined by Carlos Monge in the 1940s in the Peruvian Andes as consisting of excess polycythemia. Hurtado et al performed studies in the Peruvian Andes in the 1950s to 1960s which defined acclimatization in healthy altitude natives, including polycythemia, moderate pulmonary hypertension, and low systemic blood pressure (BP). Electrocardiographic changes of right ventricular hypertrophy (RVH) were noted. Acclimatization of newcomers to altitude involves hyperventilation stimulated by hypoxia and is usually benign. Acute mountain sickness (AMS) in travelers to altitude is characterized by hypoxia-induced anorexia, dyspnea, headache, insomnia, and nausea. The extremes of AMS are high-altitude cerebral edema and high-altitude pulmonary edema. The susceptible high-altitude resident can lose their tolerance to altitude and develop CMS, also referred to as Monge disease. The CMS includes extreme polycythemia, severe RVH, excess pulmonary hypertension, low systemic BP, arterial oxygen desaturation, and hypoventilation.