Gender Differences in the Predictive Value of Obesity Indices for Insulin Resistance in Adult Mexican Individuals

BACKGROUND

Obesity-linked insulin resistance (IR) is an important risk factor for metabolic diseases, and anthropometric indices are commonly used for risk assessment.

AIM

The study aimed to assess possible differences between women and men in the predictive value and association of nine obesity indices with IR, as assessed by HOMA-IR, in a nondiabetic adult population.

METHODS

The cross-sectional study included individuals recruited from a hospital in Mexico City. Indices evaluated were waist circumference (WC), hip circumference (HC), body mass index (BMI), waist-to-hip ratio, waist-to-height ratio, visceral adiposity index, body adiposity index (BAI), relative fat mass (RFM), and conicity index (CI). Fasting plasma glucose and insulin were measured to calculate HOMA-IR. Correlation analysis was performed between obesity indices and HOMA-IR. Receiver operating characteristics curve analyses were performed to determine predictive accuracy and cut-off values of obesity indices for IR. A binary logistic regression (BLR) analysis with OR calculation was performed to determine the strength of association with HOMA-IR.

RESULTS

We included 378 individuals (59% females, mean age 46.38 ±12.25 years). The highest Pearson coefficient value was observed for BMI among women, while among men, the highest values were found for BMI and BAI. WC among women, and BAI and RFM among men showed the highest sensitivity, while the highest specificity was observed for WHR among women and WC among men with respect to insulin prediction. In the adjusted BLR model, BMI, WC, and WHR among women and WC and RFM and BAI among men were independently associated with IR, showing the highest odds ratio (OR).

CONCLUSION

In Mexican adults, WC, WHR, RFM and BAI could be complementary tools for BMI in screening for IR.

Effect of APOB gene polymorphisms on body mass index, blood pressure, and total cholesterol levels: A cross-sectional study in Mexican population

APOB gene polymorphisms are considered risk factors for the development of dyslipidemia, hypertension, and cardiovascular disease (CVD) in several populations. In Mexico, these pathologies are frequent and studies regarding this gene are scarce. The aim of this cross-sectional study was to determined genotype, allele, and haplotype frequencies of APOB polymorphisms and performed analyses of association among the biochemical, hemodynamic, anthropometrical, and genetic variables. Blood samples were taken from 361 subjects from unselected Mexican population for biochemical analysis and for deoxyribonucleic acid extraction; besides blood pressure and body mass index (BMI) were measured. APOB polymorphisms rs934197, rs533617, rs693, and rs1042031 were genotyped by polymerase chain reaction (PCR)-restriction fragment length polymorphism; whereas, rs17240441 and c.66_67insCTGCTG were genotyped by PCR followed by electrophoresis. Genotype and allele frequencies were obtained by simple counting and deviations from Hardy-Weinberg equilibrium (HWE) were calculated by chi-square test. The effect of the polymorphisms on the quantitative variables was determined using analysis of variance, Student's t test, Pearson's and Spearman's correlations and multiple linear regression models. All the polymorphisms were within HWE. Frequencies of mutated alleles were highly heterogeneous: rs934197-T 33.6%, rs17240441-D 39.3%, c.66_67insCTGCTG-I 3.9%, rs533617-G 0.9%, rs693-T 40.5%, and rs1042031-G 17.3%. Chronic degenerative diseases were frequent in the studied population: overweight-obesity 55.1%, dyslipidemia 45.8%, and hypertension 23.5%. The association analyses showed that despite adjustments for age and sex the mutated alleles rs934197-T, rs1042031G, c.66_67-insCTGCTG-I, and rs533617-G, were related to lower values of BMI, total cholesterol (TC), systolic blood pressure, and diastolic blood pressure, respectively. All polymorphisms analyzed except rs533517 and c.66_67insCTGCTG showed high frequencies of the mutated allele, making them useful for association studies. Our results revealed that, APOB gene polymorphisms could be contributing to the development of several chronic diseases, such as essential hypertension, dyslipidemias, obesity, among others. However, specific studies with each pathology are needed to know the possible implications of the polymorphisms.

Association of rs2000999 in the haptoglobin gene with total cholesterol, HDL-C, and LDL-C levels in Mexican type 2 diabetes patients

Recently, studies have shown significant association between the rs2000999 polymorphism in the haptoglobin-encoding gene (HP) and low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels, which are important risk factors for cardiovascular diseases. However, the association of rs2000999 with serum lipids in Latin American diabetic populations is still uncharacterized. Here, we analyzed the association of rs2000999 with TC, high-density lipoprotein cholesterol (HDL-C), and LDL-C levels in 546 Mexican adults with type 2 diabetes (T2D) and in 654 controls without T2D. In this observational case-control study we included adults from 4 centers of the Mexican Social Security Institute in Mexico City recruited from 2012 to 2015. TC, HDL-C, LDL-C, triglycerides (TG), and glucose levels were measured by an enzymatic colorimetric method. The variant rs2000999 was genotyped using TaqMan real time polymerase chain reaction. The percentage of Native-American ancestry showed a negative association with the rs2000999 A allele. In contrast, the rs2000999 A allele had a strong positive association with European ancestry, and to a lesser extent, with African ancestry. Linear regression was used to estimate the association between the variant rs2000999 and lipid concentrations, using different genetic models. Under codominant and recessive models, rs2000999 was significantly associated with TC and LDL-C levels in the T2D group and in controls without T2D. In addition, the group with T2D showed a significant association between the variant and HDL-C levels. In summary, the rs2000999 A allele in Mexican population is positively associated with the percentage of European and negatively associated with Native American ancestry. Carriers of the A allele have increased levels of TC and LDL-C, independently of T2D diagnosis, and also increased concentrations of HDL-C in the T2D sample.

Association between BDNF Val66Met polymorphism and generalized anxiety disorder and clinical characteristics in a Mexican population: A case-control study

The aim of the present case-control study was to explore the association between BDNF Val66Met (rs6265) polymorphism and generalized anxiety disorder in Mexican individuals, and whether this polymorphism plays a role in the symptomatology of anxiety.A total of 212 subjects were included in the study. Around 75 patients with generalized anxiety disorder were diagnosed by psychiatrists based on the DSM-IV instrument and 137 unrelated subjects psychiatrically healthy were used as comparison group. The subclinical symptomatology in patients was assessed with the State-Trait Anxiety Inventory. BDNF rs6265 genotypes were analyzed using the polymerase chain reaction end-point method.The association between BDNF Val66Met with the risk for generalized anxiety disorder was evaluated using 4 inheritance models. The present study showed that carrying the Met allele confers increased risk for the presence of generalized anxiety disorder (χ = 4.7, P = .03; OR (95%) 1.96 (1.05-3.56)) when patients with generalized anxiety disorder were compared with the comparison group.Our results provide evidence of an association between the Val66Met polymorphism of the BDNF gene and generalized anxiety disorder in a Mexican population. However, no association was observed between this polymorphism and the symptomatology of anxiety.

The UCP2 -866G/A, Ala55Val and UCP3 -55C/T polymorphisms are associated with premature coronary artery disease and cardiovascular risk factors in Mexican population

We examined the role of UCP gene polymorphisms as susceptibility markers for premature coronary artery disease (pCAD). The UCP2 Ala55Val (C/T rs660339), UCP2 -866G/A (rs659366), and UCP3 -55C/T (rs1800849) polymorphisms were genotyped in 948 patients with pCAD, and 763 controls. The distribution of the UCP2 A55V (C/T rs660339) and UCP3 -55 (rs1800849) was similar in patients and controls. However, under a recessive model, the UCP2 -866 (rs659366) A allele was associated with increased risk of developing pCAD (OR = 1.43, Pc = 0.003). On the other hand, patients with pCAD and UCP2 A55V (rs660339) TT showed high levels of visceral abdominal fat (VAF) (Pc = 0.002), low levels of subcutaneous abdominal fat (SAF) (Pc = 0.001) and high VAT/SAT ratio (Pc < 0.001). Also, patients with UCP2 -866 (rs659366) AA showed increased levels of VAF (Pc = 0.003), low levels of SAF (Pc = 0.001) and a high VAT/SAT ratio (Pc = 0.002), whereas patients with the UCP3 -55 (rs1800849) TT presented high levels of VAF (Pc = 0.002). The results suggest the association of the UCP2 -866 (rs659366) polymorphism with risk of developing pCAD. Some polymorphisms were associated with abdominal fat levels and cardiovascular risk factors.

CAPN3, DCT, MLANA and TYRP1 are overexpressed in skin of vitiligo vulgaris Mexican patients

Vitiligo is a disorder causing skin depigmentation, in which several factors have been proposed for its pathogenesis: Environmental, genetic and biological aspects of melanocytes, even those of the surrounding keratinocytes. However, the lack of understanding of the mechanisms has complicated the task of predicting the development and progression. The present study used microarray analysis to characterize the transcriptional profile of skin from Vitiligo Vulgaris (VV) patients and the identified transcripts were validated using targeted high-throughput RNA sequencing in a broader set of patients. For microarrays, mRNA was taken from 20 skin biopsies of 10 patients with VV (pigmented and depigmented skin biopsy of each), and 5 biopsies of healthy subjects matched for age and sex were used as a control. A signature was identified that contains the expression pattern of 722 genes between depigmented vitiligo skin vs. healthy control, 1,108 between the pigmented skin of vitiligo vs. healthy controls and 1,927 between pigmented skin, depigmented vitiligo and healthy controls (P<0.05; false discovery rate, <0.1). When comparing the pigmented and depigmented skin of patients with vitiligo, which reflects the real difference between both skin types, 5 differentially expressed genes were identified and further validated in 45 additional VV patients by RNA sequencing. This analysis showed significantly higher RNA levels of calpain-3, dopachrome tautomerase, melan-A and tyrosinase-related protein-1 genes. The data revealed that the pigmented skin of vitiligo is already affected at the level of gene expression and that the main differences between pigmented and non-pigmented skin are explained by the expression of genes associated with pigment metabolism.

Should the dose of folic acid be adjusted for Mexican population? The pilot prevention program implemented in Nuevo Leon, Mexico

In 1980 Smithells et al. reported that the intake of folic acid (FA) prevents the recurrence of neural tube defects (NTDs) [1]. After this and several other studies were conducted, the intake of 400 micrograms of folic acid per day, at least three months before and three months during pregnancy for prevention of NTD, was proposed [2,3,4]. Other strategies were also developed to increase folate blood levels in woman of childbearing age such as promoting the consumption of folate rich foods and food fortification (flour and most recently rice) [5]. Nevertheless, results have not been as expected due to poor consumption of folic acid supplements [6]. As a result, in the year 2000, a novel strategy was developed in order to increase folate blood levels in Mexican women. The results of the strategy are presented, as well as, a discussion about how to personalize a program for different populations.

Study on genes of the serotonergic system and suicidal behavior: protocol for a case-control study in Mexican population

BACKGROUND

Suicidal behavior is a leading cause of injury and death worldwide. Several studies have provided a possible relationship between genetic factors and suicidal behavior. Also, these studies have shown evidence for altered serotonergic neural transmission in the pathogenesis of suicidal behavior. In addition, genes pertaining to the serotonergic system have been proposed as candidates to establish biological correlates between suicidal behavior and the serotonergic system. The most studied genes are SCL6A4, HTR2A, HTR2C, HTR1A, HTR1B, TPH-1, and TPH-2. To get a comprehensive understanding of the association with suicidal behavior we will conduct genotype assays studies in a Mexican population.

METHODS/DESIGN

We will conduct a case-control study. The population sample will comprise adolescent and adult patients admitted for attempted of suicide and diagnosed by a psychiatrist. A peripheral blood sample will be taken from all the subjects (cases and controls). Genomic DNA from the leukocytes blood sample will be extracted. The genotypes of interest are distributed in the following genes: SCL6A4, HTR2A, HTR1A, HTR1B, HTR2C, TPH-2 and TPH-1. All the samples will be analyzed using a polymerase chain reaction (PCR) end-point method. We will evaluate the Hardy-Weinberg Equilibrium. The chi-squared test or Fisher's exact test will be used to compare genotype and allele frequencies between control and case groups. The Quanto 1.2 software will measure the sample size of the association. For all the association analyses the level of significance will be set at p = 0.05 and the confidence interval at 95%.

DISCUSSION

Suicidal behavior has been increase in Mexico, principally in young population. Our study will demonstrate the association between serotoninergic genes and suicide behavior in Mexican population.

A systematic review and meta-analysis of Toxoplasma gondii infection among the Mexican population

BACKGROUND

Toxoplasmosis is a disease caused by Toxoplasma gondii and at least one-third of the world's population has detectable T. gondii antibodies. The seroprevalence of T.gondii ranges from 15% to 50% among the Mexican general population. The aim of this work was to determine the mean prevalence and weighted mean prevalence of T. gondii infection, and to evaluate the epidemiological transition of infection in Mexico.

METHODS

Pub Med, Lilacs, Medline, Latindex, Google Scholar data bases were searched to retrieve reports from 1951 up to 2012 regarding prevalence data, diagnostic tests and risk factors of infection among the adult population. Data collection and criteria eligibility was established in order to determine the crude prevalence (proportion of positive cases) of each study, together with weighted population prevalence according to individual research group categories to limit the bias that may impose the heterogeneous nature of the reports. A Forest Plot chart and linear regression analysis were performed by plotting the prevalence of infection reported from each study over a period of sixty years.

RESULTS

A total of 132 studies were collected from 41 publications that included 70,123 individuals. The average mean prevalence was 27.97%, and weighted mean prevalence was 19.27%. Comparisons among different risk groups showed that the weighted prevalence was higher in women with miscarriages (36.03%), immunocompromised patients (28.54%), mentally-ill patients (38.52%) and other risk groups (35.13%). Toxoplasma infection among the Mexican population showed a downward trend of 0.1%/year over a period of sixty years that represents a 5.8% reduction in prevalence.

CONCLUSIONS

This analysis showed a downward trend of infection; however, there are individuals at high risk for infection such as immunocompromised patients, mentally-ill patients and pregnant women. Further research is required to provide better prevention strategies, effective diagnostic testing and medical management of patients. Educational efforts are required to avoid the transmission of infection in populations that cannot be controlled by drugs alone.