Emergent cardiovascular risk factor: homocysteine

Involvements of Hyperhomocysteinemia in Neurological Disorders

Homocysteine (HCY), a physiological amino acid formed when proteins break down, leads to a pathological condition called hyperhomocysteinemia (HHCY), when it is over a definite limit. It is well known that an increase in HCY levels in blood, can contribute to arterial damage and several cardiovascular disease, but the knowledge about the relationship between HCY and brain disorders is very poor. Recent studies demonstrated that an alteration in HCY metabolism or a deficiency in folate or vitamin B12 can cause altered methylation and/or redox potentials, that leads to a modification on calcium influx in cells, or into an accumulation in amyloid and/or tau protein involving a cascade of events that culminate in apoptosis, and, in the worst conditions, neuronal death. The present review will thus summarize how much is known about the possible role of HHCY in neurodegenerative disease.

Predictors of cardiorespiratory fitness in female and male adults with different body mass index: National Health and Nutrition Examination Survey 1999-2004 dataset

BACKGROUND

The aim of this study was to explore factors affecting cardiorespiratory fitness in males and females with different body mass index (BMI).

METHODS

The National Health and Nutrition Examination Survey 1999-2004 data were used for this retrospective study. Estimated maximal oxygen uptake (VO_2max) is surrogate for cardiorespiratory fitness (CRF). Univariate and multivariate linear regression analyses were performed to explore whether study variables were associated with estimated VO_2max stratified by gender and BMI categories.

RESULTS

A total of 3292 subjects 20-49 years of age were included in the analysis. CRF significantly decreased as BMI increased in both females and males. Ethnic difference was found in normal BMI in both genders and obese females; homocysteine was significantly negatively associated with estimated VO_2max, as was total cholesterol. Obese male subjects with diabetes had a lower estimated VO_2max than those without diabetes, and C-reactive protein (CRP) level and vitamin B12 level were significantly negatively associated with CRF. Female subjects with diabetes had higher estimated VO_2max than those without diabetes. Folate was significantly positively correlated with estimated VO_2max, whereas CRP was negatively correlated in obese female.

CONCLUSIONS

There are different predictors of CRF in males and females, and in individuals with different BMI. Key messages Different BMI classes are associated with different predictors of cardiorespiratory fitness. Indicators of cardiorespiratory fitness differ between sexes.

Differences in Mexican American and Non-Hispanic White veterans' homocysteine levels

PURPOSE

To compare homocysteine (Hcy) levels and possible modulatory factors, such as nutrient or supplement intake, between Mexican American and Non-Hispanic White (NHW) male military veterans scoring at high- versus low-risk for stroke.

DESIGN

A cross-sectional survey with a high and low stroke risk biomarkers substudy.

METHODS

Voluntary participants were Mexican American (n=109) and NHW (n=120) veteran outpatients 54 to 85 years of age at a Southwestern Veterans Administration (VA) medical center. Measures included food frequency, health history, and stroke risk scale derived from the Framingham Study. Biomarker subgroups, 30 Mexican American and 30 NHW, half of each group scoring high or low on stroke risk, who were tested for morning fasting blood levels of Hcy, B12, and folate.

FINDINGS

In the cross-sectional study (n=229), nutrient intake was comparable between ethnic groups. In the substudy, Mexican Americans (n=30) with high or low stroke risk scores and NHW (n=30) with high stroke risk scores had elevated Hcy levels (12.5; 11.9; 11.4 micromol/L respectively) compared to NHW veterans with low stroke risk scores (7.8 micromol/L) even after controlling for age, education, folate, diabetes, and smoking pack-years (p=.001). Mexican Americans compared to NHW were significantly more likely to be in the preclinical (17% versus 3% >10 micromol/L) and clinical ranges (69% versus 35% >15 micromol/L) for Hcy.

CONCLUSIONS

Mexican Americans showed higher levels of Hcy whether they scored high or low for stroke, and greater representation in clinical and preclinical Hcy ranges compared to NHW veterans. The Framingham-derived, predominantly NHW population-based stroke risk measure might require ethnically relevant stroke risk factors for Mexican Americans.

Influence of Age and Coronary Artery Disease on Homocysteine Levels in the Young Old Compared With the Old Old and the Oldest Old

A total of 172 elderly individuals, divided into case and control groups based on the diagnosis of coronary artery disease, underwent coronary angiography to investigate the influence of age and coronary artery disease on homocysteine levels. The subjects were divided into three age ranges: 65-74 years, 75-79 years, and 80 years and older. Continuous homocysteinemia was associated with a risk ratio for coronary artery disease of 1.07 for each micromol/L increase in homocysteine level. Hyperhomocysteinemia (values above 14 micromol/L) constituted an independent risk factor for coronary artery disease, with a risk ratio of 2.03. There was a progression of homocysteine levels between the young old and the oldest old only among the case group elderly. There was no difference among the control group elderly. There were no significant differences in vitamin levels. The rise in homocysteine levels from the young old to the oldest old may be considered not a normal pattern, but rather a pattern associated with coronary artery disease.