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Biomedical subjects

M E Valencia

Publications and source records attributed to M E Valencia.

At least 19 recordsLinked to original sources
PubMed2007

Body composition by the four-compartment model: validity of the BOD POD for assessing body fat in Mexican elderly.

OBJECTIVE: The aims of this study were to validate BOD POD in a wide sample of healthy and independent Mexican elderly men and women subjects using the 4 compartment (4C) model as the reference method, and to evaluate the assumptions of the densitometric two-compartment (2C) model. DESIGN: Cross-sectional study designed to assess body composition and validation of a method based on 2C model (BOD POD). SETTING: Urban and rural regions of Sonora, Mexico. SUBJECTS: Two hundred and two free-living subjects >or=60 years old were completed in this study. METHODS: Body density and body fat were measured by the BOD POD, total body water by deuterium dilution and total body bone ash by dual energy X-ray absorptiometry. Body composition was determined using Baumgartner's equation. RESULTS: Percent body fat by the 4C model was 31.2 and 42.5% in men and women, respectively (P<0.001). Group mean accuracy of body fat by BOD POD against that of the 4C model showed an effect of sex (P<0.001), but not the method (P=0.27). Results of individual accuracy showed no significant difference with the identity line and the slope was significantly different from zero or a slope similar to one. Precision assessed by model R (2) was high for all subjects and for men and women by separate. The standard error of the estimate was low for all and for men and women by separate. Bland and Altman analysis showed no significant bias. CONCLUSION: The BOD POD technique is a valid and reliable method compared to the 4C model and it could be applied in subjects with similar physical and anthropometric characteristics to subjects of this study.

Absorptiometry, Photon↗
PubMed2006

Total energy expenditure, resting metabolic rate and physical activity level in free-living rural elderly men and women from Cuba, Chile and México.

OBJECTIVE: The objective of this study was to assess total energy expenditure (TEE), resting metabolic rate (RMR) and physical activity level (PAL), and to estimate energy requirements (ERs) in free-living elderly subjects from Cuba, Chile and Mexico. DESIGN: Cross-sectional study designed to estimate ERs. SETTING: Rural regions of Cuba, Chile and Mexico. SUBJECTS: Forty subjects >60 years old were selected to participate in this study. INTERVENTIONS: A dose of doubly labeled water (DLW) was administered and urine samples were collected in the following 12-14 days. From the isotopic analysis, TEE was derived. RMR was measured by indirect calorimetry. RESULTS: TEE in Chilean (8.8+/-1.6 MJ/day) and Cuban (8.3+/-1.3 MJ/day) elderly was not different, and was higher for the Mexican group (9.5+/-1.5 MJ/day) (P < 0.0001). RMR was not different between countries. PAL and activity energy expenditure (AEE) were only different between Chile and Mexico (P < 0.002). For the three regions, overall PALs were 1.70+/-0.16 for male and 1.62+/-0.13 for female subjects (P < 0.02), and AEE was 3.05+/-0.66 and 2.27+/-0.66 MJ/day for male and female subjects, respectively (P < 0.001). Predictive equations (MJ/day) were RMR = 1.6447 + 0.05714 x weight (kg) + 0.449 sex (male = 1; female = 0) (R2 = 0.75; SEE = 0.479) and TEE = 3.414 + 0.0795 x weight (kg) + 1.227 x sex (male = 1; female = 0) (R2 = 0.75; SEE = 0.668). CONCLUSIONS: There were differences in TEE and PAL owing to sex and region. The average PAL in men was higher than the PAL reported either with factorial approach or with the DLW method in elderly. Predictive ER equations based on RMR and TEE gave very similar results to calculations from the 2004 FAO/WHO/UNU report.

Aged↗
PubMed2006

Reduction in liver-related hospital admissions and deaths in HIV-infected patients since the year 2002.

Since the advent of highly active antiretroviral therapy (HAART), complications of chronic liver disease (CLD) have emerged as one of the leading causes of hospital admission and death among HIV-infected patients with chronic hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infections. The impact of CLD on hospital admissions and deaths in HIV-infected patients attended at one reference HIV hospital in Madrid during the last 9 years was analysed. All clinical charts from January 1996 to December 2004 were retrospectively examined. Demographics, discharge diagnosis, complications during inhospital stay and causes of death were recorded. A total of 2527 hospital admissions in 2008 distinct HIV-infected persons were recorded. Overall, 84% were iv drug users; mean age was 37 years and the mean CD4 count was 224 cells/muL. Both mean age and CD4 count significantly increased during the study period (P < 0.01). Overall, 42% of hospitalized patients were on antiretroviral therapy. Decompensated CLD was the cause of admission and/or developed during hospitalization in 345 patients (14%). Admissions caused by decompensated CLD increased significantly from 9.1% (30/329) in 1996 to 26% (78/294) in 2002. A significant steady decline occurred since then, being 11% (29/253) in the year 2004. Similarly, inhospital liver-related deaths were 9% (5/54) in 1996, peaked to 59% (10/17) in 2001 and declined to 20% (3/15) in the year 2004. Chronic hepatitis C was responsible for admissions and/or deaths in 73.5% of CLD cases. In conclusion, the rate of liver-related hospital admissions and deaths among HIV-infected patients peaked in the year 2002 and has steadily declined since then. A slower progression to liver cirrhosis in patients on HAART, avoidance of hepatotoxic antiretroviral drugs and more frequent use of anti-HCV therapy in HIV/HCV-coinfected patients could account for this benefit.

Adult↗
PubMed2004

Prevalence and intensity of intestinal parasitic infections in relation to nutritional status in Mexican schoolchildren.

Undernutrition and intestinal parasitic infections affect childhood development and morbidity in many developing countries. Undernutrition may increase susceptibility to parasitic infections which in turn impair the nutritional status of the host. The relationship between intestinal parasitic infections and nutritional status in 400 Mexican schoolchildren was investigated. More than half of the children in the study showed intestinal parasites and polyparasitism. The prevalence of helminth infections was significantly higher in Oaxaca than in Sinaloa (P < 0.05). Z scores for weight-for-age (WA) and height-for-age (HA) were much lower in children of Oaxaca than in Sinaloa (P < 0.001). A significantly higher Z score for weight-for-height (WH), WA, and HA were found in non-infected versus infected children (P < 0.05). Higher prevalences of intestinal infections were found in children with lower HA and WA than in normally nourished children (P < 0.05). Higher intensities of Ascaris lumbricoides and Trichuris trichiura were found in the schoolchildren of Sinaloa than in Oaxaca (P < 0.01). Negative and significant associations were found between Hymenolepis nana and T. trichiura infection (eggs per gram) and nutritional status. Intestinal parasitic infections may be regarded as main risk factors associated with poor nutritional status in Mexican schoolchildren.

Analysis of Variance↗
PubMed2004

Determination of body composition using air displacement plethysmography, anthropometry and bio-electrical impedance in rural elderly Mexican men and women.

BACKGROUND AND AIMS: Air displacement plethysmography with the BOD-POD is a new densitometry technique, and has been found to be an accurate method to measure body composition. The aim of this study was to assess body composition in a group of free living healthy subjects 60 years of age or older from a rural area of Northwest Mexico, and to evaluate body composition by anthropometry and bioelectrical impedance (BIA) using equations reported for other elderly populations. METHODS: Body composition was evaluated in 21 women and 26 men with the BOD-POD, by anthropometry, and BIA and compared to different equations using the Bland- Altman procedure. RESULTS: Body fat in elderly women and men was 42.7 and 30.2 % respectively. In women, Segal's equation using BIA 1, based on standing height, showed no significant differences with the BOD-POD. There was satisfactory agreement between Segal's equation and BOD-POD. In men similar results was found with Deurenberg's equation using B1A 2 based on recumbent length. CONCLUSIONS: Segal's and Deurenberg's equations were accurate and precise for the estimation of body fat in the elderly of this study. The use of these equations could improve the estimation of body composition for similar elderly subjects. Further studies are recommended with a larger size samples to include elderly subjects from other Latin American countries.

Aged↗
PubMed2004

The usefulness of stable isotopes in nutrition and human health: the application of mass spectrometry and 13C-breath tests to detect helicobacter pylori infection.

The interest in Helicobacter pylori has escalated in recent years. H. pylori may produce a chronic gastric infection which is usually life-long and many epidemiological studies have shown that this is the most common bacterial infection throughout the world involving 50% of the world population. Thus, it is clear that the diagnosis of H. pylori infection represents at least a key step in the management of many of the patients referred to the gastroenterologist. Additionally, due to the wide range and relevance of pathologies possibly related to this infection, from micronutrient malnutrition and co-infections to malignancies, there is the potential for H. pylori to be a major health problem. Improved methods for the diagnosis and follow up treatment of the infection have been developed. Use of stable isotopes as non-invasive and safe diagnostic methods, namely (13C) breath tests, has been the key to a new era of research in H. pylori epidemiology and diagnosis as well as the establishment of eradication therapies. This non-invasive nuclear technique, that is considered the gold standard for the diagnosis of this bacterial infection, has successfully been standardized and implemented along Latin America. Taking into account the high prevalence of this bacterial infection, the impact of this technique in the whole region is very high. In this article we discuss several aspects of this methodology in order to harmonize the application of this method in developing regions.

Breath Tests↗
PubMed2003

Estimation of body fatness from body mass index and bioelectrical impedance: comparison of New Zealand European, Maori and Pacific Island children.

OBJECTIVE: To compare percentage body fat (%BF) for a given body mass index (BMI) among New Zealand European, Maori and Pacific Island children. To develop prediction equations based on bioimpedance measurements for the estimation of fat-free mass (FFM) appropriate to children in these three ethnic groups. DESIGN: Cross-sectional study. Purposive sampling of schoolchildren aimed at recruiting three children of each sex and ethnicity for each year of age. Double cross-validation of FFM prediction equations developed by multiple regression. SETTING: Local schools in Auckland. SUBJECTS: Healthy European, Maori and Pacific Island children (n=172, 83 M, 89 F, mean age 9.4+/-2.8(s.d.), range 5-14 y). MEASUREMENTS: Height, weight, age, sex and ethnicity were recorded. FFM was derived from measurements of total body water by deuterium dilution and resistance and reactance were measured by bioimpedance analysis. RESULTS: For fixed BMI, the Maori and Pacific Island girls averaged 3.7% lower %BF than European girls. For boys a similar relation was not found since BMI did not significantly influence %BF of European boys (P=0.18). Based on bioimpedance measurements a single prediction equation was developed for all children: FFM (kg)=0.622 height (cm)(2)/resistance+0.234 weight (kg)+1.166, R(2)=0.96, s.e.e.=2.44 kg. Ethnicity, age and sex were not significant predictors. CONCLUSIONS: A robust equation for estimation of FFM in New Zealand European, Maori and Pacific Island children in the 5-14 y age range that is more suitable than BMI for the determination of body fatness in field studies has been developed.

Adipose Tissue↗
PubMed2003

Body composition by hydrometry (deuterium oxide dilution) and bioelectrical impedance in subjects aged >60 y from rural regions of Cuba, Chile and Mexico.

BACKGROUND: In Latin American and Caribbean countries such as Chile, Mexico and Cuba, the population over 60 y has increased steadily. In this age group, there is scarce information about body composition, particularly for those living in rural areas. OBJECTIVE: The purpose of this study was to determine body composition in free-living and healthy elderly subjects >60 y from rural areas of Chile, Cuba and Mexico using deuterium oxide dilution and bioelectrical impedance (BIA) and to develop and cross-validate a predictive equation for this group of subjects by BIA for future use as a field technique. SUBJECTS: The study included 133 healthy subjects (73 males and 60 females) >60 y from rural regions of Cuba, Chile and Mexico. MEASUREMENTS: Total body water, body weight, height and other anthropometric and BIA variables (resistance and reactance) were measured. METHODS: Total body water was determined by deuterium oxide dilution, and fat-free mass (FFM)/fat mass were derived from this measurement. The total sample was used in a split-sample internal cross-validation. BIA and other anthropometric variables were integrated to multiple regression model to design the best predictive equation, which was validated in the other sample. ANOVA, multiple regression and Bland and Altman's procedure were used to analyze the data. RESULTS: Body weight, percentage of fat and fat-free mass were lower in the Cuban men and women compared with Chilean and Mexican men and women. The best predictive equation of the FFM was: FFM kg=(-7.71+(H(2)/R x 0.49)+(country or ethnicity x 1.12)+(body weight x 0.27)+(sex x 3.49)+(Xc x 0.13)), where H(2) is height(2) (cm); R is resistance (Omega); country: Chile=1, Mexico=2 and Cuba=3; sex: women=0 and men=1; body weight (kg) and Xc is reactance (Omega). R(2) was 0.944 and the root mean square error (RMSE) was 2.08 kg. The mean+/-s.d. of FFM prediction was 44.2+/-9.2 vs 44.6+/-10.1. The results of cross-validation showed no significant difference with the line of identity, showing that the predicted equation was accurate. The intercept (=-0.32) was not significantly different from zero (P=0.89) and the slope (=1.02) not significantly different from 1.0 (P>0.9). The R(2) was 0.86, RMSE=3.86 kg of FFM and the pure error was 3.83. CONCLUSION: The new BIA equation is accurate, precise and showed good agreement. The use of this equation could improve the estimates of body composition for the elderly population for these regions, as well as enhancing the opportunity to conduct studies in the elderly population from Latin America.

Aged↗
PubMed2002

Measuring the intakes of foods and nutrients of marginal populations in north-west Mexico.

OBJECTIVE: To describe methodological issues regarding the measurement of food intake of marginal populations in the north-west of Mexico. METHODS: Dietary data from three sources were analysed. The Sonora State Food Basket Study (505 individuals from all ages, both sexes, high, medium and low income, and from urban and rural settings), 144 individuals from rural Indian communities, and 152 low-income urban women. Methods of dietary data collection were single 24-hour recalls for the first two studies, and four non-consecutive 24-hour recalls as well as a food-frequency questionnaire (FFQ) for low-income urban women. RESULTS: The food patterns in the three studies showed similar core foods; however, food diversity resulted in 19, 13 and 57 different foods reported by 90% of the population in the state, Indian communities and urban women, respectively. Mean intakes of selected food components in the sample of urban women vs. a representative sample of the population of the state were similar, although smaller variation in consumption was observed in urban women with repeated 24-hour recalls. Inter-individual variation in intake of food components was similar in the state and urban women samples, but the Indian communities showed lower coefficients of variation (CVs). Use of four 24-hour recalls decreased the inter-individual variation in food component intakes of low-income urban women, especially for vitamin intakes. The FFQ did not show an additional decrease in inter-individual variation for macronutrients, but reduced even more the CVs for vitamins. Intra-individual variation was higher than inter-individual variation for urban women's intakes when estimated by repeated 24-hour recalls. This effect was reversed when estimated by duplicate food frequencies. Ratios of intra-individual to inter-individual variation in food intake were lower for Mexican when compared with US women. These results should be considered, especially for association analysis of low-income women's diets and health outcomes.

Adult↗
PubMed2001

Dietary fiber and lifestyle influence serum lipids in free living adult men.

OBJECTIVE: The aim of this study was to determine the effect of dietary fiber consumption and lifestyle on serum lipids in adult men with non-restricted diet and physical activity. METHODS: Two groups of 19 men were classified as high (48 g/day) and low fiber groups (27 g/day). Anthropometry, food frequency, daily weighed intakes and physical activity were done for a seven-day period. Fasting blood was collected and serum was analyzed for triglycerides, total cholesterol and lipoprotein cholesterol fractions. RESULTS: Crude correlation coefficients showed that total cholesterol was negatively associated with physical activity, total dietary fiber and P/S ratio (r = 0.52; p < 0.001. r = -0.44; p < 0.01, r = 0.51, p < 0.001). LDL-C was also correlated negatively with total dietary fiber and P/S ratio (r = -0.34, p < 0.03; r = -0.53, p < 0.01). It was also positively associated with dietary cholesterol and body weight (r = 0.34, p < 0.03; r = 0.31, p < 0.05). Serum triglycerides had an inverse association with total dietary fiber and physical activity (r = -0.30: p < 0.05; r = -0.45, p < 0.004). After controlling for energy intake, total fat, saturated fat, dietary cholesterol, physical activity and body mass index, LDL-C/HDL-C, and TC/HDL-C, remained significantly associated with dietary fiber (r = 0.34; p < 0.05 and r = -0.38; p < 0.02, respectively). CONCLUSIONS: This study provides evidence in free living men that there is an association between dietary fiber intake and favorable lipid status and that lifestyle defined by socioeconomic status, physical activity and the quality of the dietary fat intake can play an important role. Public health nutrition advice and policy should continue to emphasize the importance of these factors.

Adult↗
PubMed2001

Protein quality evaluation in rats of typical diets for 4- to 6-year-old children from different socioeconomic areas living in Oaxaca, Mexico.

Legumes and cereals are principal sources of energy and protein in developing countries. In Oaxaca, Mexico, corn is the primary agricultural crop, therefore corn tortillas and beans are the main energy and protein sources. The objective of this study was to evaluate the protein quality in rats of typical diets for 4- to 6-year-old children from different socioeconomic areas in Oaxaca, Mexico. Composite diets representing the typical diets were formulated and fed to male weanling rats for 10 days. A control diet using casein as the reference diet and one free of nitrogen were included in the study. The apparent protein digestibility was determined in rats using the chromic oxide marker technique and the data was statistically analyzed for differences between control and experimental diets. Rats fed the diet of low income children gained about 2 g/day compared to about 3.8 g/day for the rats fed the control (casein) diet and had the lowest weight gain/g of protein intake. The NPR was 3.52 compared to 4.31 for the control diet. This diet is 67% vegetable protein and 33% animal protein. The diet for the medium income group contained a higher percentage of animal protein, 76% and thus higher digestibility, 78%. The results of this study indicate that the protein quality of children's diets in Oaxaca, Mexico, need to be improved.

Animals↗
PubMed2000

Daily energy expenditure in Mexican and USA Pima indians: low physical activity as a possible cause of obesity.

BACKGROUND: Obesity is caused by an imbalance between energy intake and energy expenditure. However, it is unknown whether increased physical activity protects susceptible populations against the development of obesity and type 2 diabetes. OBJECTIVE: To investigate the potential protective role of environment and physical activity against obesity by measuring total energy expenditure in Mexican and USA Pima Indians. METHODS: We compared the physical activity level of 40 (17 female and 23 male; 37+/-11 y, 66+/-13 kg) Mexican Pima Indians from a remote, mountainous area of Northwest Mexico, with 40 age-and-sex matched (17 female and 23 male; 37+/-12 y, 93+/-22 kg) Pima Indians from the Gila River Indian Community in Arizona, USA. We measured total energy expenditure (TEE) by doubly labeled water and calculated physical activity by different methods: physical activity level (PAL) as the ratio of TEE on resting metabolic rate (RMR), TEE adjusted for RMR by linear regression, activity energy expenditure adjusted for body weight (AEE), and activity questionnaire. RESULTS: Physical activity was higher in Mexican Pima Indians when compared with USA Pima Indians as assessed by PAL (1.97+/-0.34 vs 1.57+/-0.16, P<0.0001), TEE adjusted for RMR (3289+/-454 vs 2671+/-454 kcal/day, P<0.0001) and AEE adjusted for body weight (1243+/-415 vs 711+/-415 kcal/day, P<0. 0001). Questionnaires revealed more time spent on occupational activities among Mexican Pima compared with USA Pima (23.9+/-13.3 vs 12.6+/-13.9 h/week, P<0.001). CONCLUSION: These data support a significant role for physical activity in the prevention of obesity in genetically susceptible populations. International Journal of Obesity (2000)24, 55-59

Adult↗
PubMed2000

Diagnostic utility of a multiplex herpesvirus PCR assay performed with cerebrospinal fluid from human immunodeficiency virus-infected patients with neurological disorders.

We used a multiplex nested-PCR assay for the simultaneous detection in cerebrospinal fluid (CSF) of five human herpesviruses (HVs) (cytomegalovirus [CMV], Epstein-Barr virus [EBV], varicella-zoster virus [VZV], herpes simplex virus [HSV], and human herpesvirus 6 [HHV-6]) in a clinical evaluation of human immunodeficiency virus (HIV)-infected patients with neurological disorders. This method, which has the advantages of being rapid and economical, would be of particular interest for the diagnosis of neurological syndromes caused by more than one HV. We studied 251 CSF samples from 219 patients. HV DNA was demonstrated in 93 (37%) of the CSF samples (34% of the patients). CMV was the HV most frequently detected in our patients (25%), while EBV, VZV, HSV, and HHV-6 DNAs were present in significantly fewer cases (7, 4, 3, and 1%, respectively). When results were compared with the final etiological diagnoses of the patients, the multiplex HV PCR showed high specificity for the diagnosis of CMV and VZV neurological diseases and for cerebral lymphoma (0.95, 0.97, and 0.99, respectively). The sensitivity of the assay was high for CMV disease (0.87), was low for cerebral lymphoma (0.33), and was not evaluable for VZV disease due to the small number of patients with this diagnosis. Nevertheless, detection of VZV DNA had possible diagnostic value in four of the nine cases, and EBV DNA amplification always predicted the diagnosis of cerebral lymphoma in patients with cerebral masses. Detection of HSV DNA was frequently associated with CMV amplification and fatal encephalitis. HHV-6 was not considered to have a pathogenetic role in the three cases in which it was detected. This multiplex HV PCR assay is a specific and clinically useful method for the evaluation of HIV-infected patients with neurological disorders related to HV.

AIDS-Related Opportunistic Infections↗