Trace determination of tetracyclines in water samples by capillary zone electrophoresis combining off-line and on-line sample preconcentration.

In this work, a sensitive and reliable method using capillary zone electrophoresis with UV detection has been developed for trace determination of tetracycline antibiotics in river, spring, and ground waters. A solid-phase extraction method using Oasis HLB was applied for off-line preconcentration and cleanup of water samples, in combination with an on-line preconcentration methodology named large volume sample stacking with polarity switching. Different parameters were optimized in order to obtain an adequate separation combined with the highest sensitivity, using 75 mM sodium carbonate (pH 10) and 1 mM EDTA as separation buffer, applying a voltage of 25 kV at 25°C. The samples were injected in water at 1 bar for 1 min, applying then -25 kV and starting the sample stacking. Sample matrix removal from the capillary was controlled by monitoring the electric current (when the 95% of the separation current is reached the stacking process is completed). The applied voltage was then switched from negative to a positive value of 25 kV in order to separate the compounds. Under optimum conditions, sensitivity enhancement factors ranged from 303 to 428 for the studied compounds. The combination of both off-line and on-line preconcentration procedures provided a total sensitivity enhancement factor about 20 000, obtaining detection limits from 67 to 167 ng/L. The precision (intra- and interday), expressed as %RSD was below 12%. Recoveries obtained from river, spring, and ground waters ranged from 87 to 96%. Thus, this procedure is suitable for monitoring these compounds in water samples.

[Norovirus detection in children with community-acquired or nosocomial diarrhea at Guillermo Grant Benavente Hospital in Concepción, Chile]. / Detección de norovirus en niños con diarrea adquirida en la comunidad o nosocomial en el Hospital Guillermo Grant Benavente de Concepción, Chile.

INTRODUCTION: Norovirus (NoV) are RNA viruses highly contagious, stable in the environment, genetically variable, and the most common cause of viral sporadic acute gastroenteritis worldwide. This is the first study carried out in Concepcion, Chile, to investigate the presence of NoV as an etiologic agent of viral diarrheas in hospitalized children. Objective. To detect the presence and genogroup of NoV in children with diarrhea and to compare it with rotavirus (RV) and adenovirus (AdV). MATERIAL AND METHODS: A one year descriptive, prospective study in children 0-14 years old. A single diarrheic stool sample per patient was analyzed for the presence of NoV, RV and AdV. Clinical data were unknown at the moment of sampling. Real time RT-PCR with Taqman™ probes for NoV and the immunocromatography VIKIA™ kit for RoV /AV detection were used. RESULTS: Infection for NoV (25.5%) was significantly higher than for RV (15.9%) and AdV (6.2%). It was even greater in infants younger than 2yr. old (n: 103): NoV 34%, RV 17.5%, AdV 7.8%. Children 2-4 yr. old had 11.8% infection of NoV and RV. Children older than 4, only had 12% RV and 4% AdV. Children hospitalized for diarrhea (n: 92) had: 21.7% of both NoV and RV, and 7.6% AdV; whereas children hospitalized for other causes (n: 53) had 32.1% NoV,5.7% RV and 3.8% AV. The proportion of infection due to NoV was significantly higher in males (31.5%) than in females (19.4%). The average frequency during the year was higher for NoV (30.3%) than for RV (14.7%) except in summer. CONCLUSION: The presence of NoV was higher than RV in children with diarrhea. NoV infection showed defined characteristics regarding age, gender, seasonal occurrence and nosocomial transmission that are important epidemiological features.

Detección de norovirus en niños con diarrea adquirida en la comunidad o nosocomial en el Hospital Guillermo Grant Benavente de Concepción, Chile / Norovirus detection in children with community-acquired or nosocomial diarrhea at Guillermo Grant Benavente Hospital in Concepción, Chile

Introduction: Norovirus (NoV) are RNA viruses highly contagious, stable in the environment, genetically variable, and the most common cause of viral sporadic acute gastroenteritis worldwide. This is the first study carried out in Concepcion, Chile, to investigate the presence of NoV as an etiologic agent of viral diarrheas in hospitalized children. Objective. To detect the presence and genogroup of NoV in children with diarrhea and to compare it with rotavirus (RV) and adenovirus (AdV). Material and Methods: A one year descriptive, prospective study in children 0-14 years old. A single diarrheic stool sample per patient was analyzed for the presence of NoV, RV and AdV. Clinical data were unknown at the moment of sampling. Real time RT-PCR with Taqman™ probes for NoV and the immunocromatography VIKIA™ kit for RoV /AV detection were used. Results: Infection for NoV (25.5%) was significantly higher than for RV (15.9%) and AdV (6.2%). It was even greater in infants younger than 2yr. old (n: 103): NoV 34%, RV 17.5%, AdV 7.8%. Children 2-4 yr. old had 11.8% infection of NoV and RV. Children older than 4, only had 12% RV and 4% AdV. Children hospitalized for diarrhea (n: 92) had: 21.7% of both NoV and RV, and 7.6% AdV; whereas children hospitalized for other causes (n: 53) had 32.1% NoV,5.7% RV and 3.8% AV. The proportion of infection due to NoV was significantly higher in males (31.5%) than in females (19.4%). The average frequency during the year was higher for NoV (30.3%) than for RV (14.7%) except in summer. Conclusion: The presence of NoV was higher than RV in children with diarrhea. NoV infection showed defined characteristics regarding age, gender, seasonal occurrence and nosocomial transmission that are important epidemiological features.

Introducción: Los norovirus (NoV) son virus ARN altamente contagiosos, resistentes, variables genéticamente y una de las etiologías más frecuente de gastroenteritis viral esporádica mundial. Este es el primer trabajo en Concepción, Chile, de búsqueda de NoV como etiología viral de diarreas en niños hospitalizados. Objetivo: Determinar la presencia y genogrupo de NoV en niños con diarrea y compararla con la frecuencia de rotavirus (RV) y adenovirus (AdV). Material y Método: Estudio descriptivo, prospectivo de un año, en niños de 0-14 años ingresados por diarrea aguda o que la adquirieron dentro del hospital. La muestra de deposiciones diarreica se tomó una sola vez por paciente. Las fichas clínicas se analizaron al finalizar el estudio etiológico. Para la detección de NoV se utilizó RPC-TR a en tiempo real con sondas Taqman® y para detección de RV/AdV, el kit VIKIA® de inmunocromatografia. Resultados: La infección por NoV (25,5%) fue significativamente más frecuente que por RV (15,9%) y AdV (6,2%). La mayor presencia de infección fue en pacientes bajo2 años de edad (n: 103): NoV 34,0%, RV 17,5%, AdV 7,8%. La detección en niños hospitalizados por diarrea fue: NoV y RV 21,7% cada uno; AdV 7,6%. En niños con diarrea nosocomial hospitalizados por otras causas se detectó NoV en 32,1%, RV en 5,7% y AdV en 3,8%. La presencia de NoV fue significativamente mayor en varones (31,5%) que en niñas (19,4%). El promedio de diarreas durante el año fue mayor para NoV (30,3%) que para RV(14,7%), excepto en verano. Discusión y Conclusión: La presencia de NoV fue mayor que la de RoV en niños con diarrea y con una tendencia nosocomial que podría deberse a las características del virus que favorece infecciones de ambiente confinado, como hospitales, asilos y cruceros. La infección por NoV presentó características definidas, en edad, género, ocurrencia estacional y relevancia nosocomial, que aportan datos epidemiológicos importantes.

Genetic effects on obesity assessed by bivariate genome scan: the Mexican-American coronary artery disease study.

OBJECTIVE: To identify the genetic determinants of obesity using univariate and bivariate models in a genome scan. RESEARCH METHODS AND PROCEDURES: We evaluated the genetic and environmental effects and performed a genome-wide linkage analysis of obesity-related traits in 478 subjects from 105 Mexican-American nuclear families ascertained through a proband with documented coronary artery disease. The available obesity traits include BMI, body surface area (BSA), waist-to-hip ratio (WHR), and trunk fat mass as percentage of body weight. Heritability estimates and multipoint linkage analysis were performed using a variance components procedure implemented in SOLAR software. RESULTS: The heritability estimates were 0.62 for BMI, 0.73 for BSA, 0.40 for WHR, and 0.38 for trunk fat mass as percentage of body weight. Using a bivariate genetic model, we observed significant genetic correlations between BMI and other obesity-related traits (all p < 0.01). Evidence for univariate linkage was observed at 252 to approximately 267 cM on chromosome 2 for three obesity-related traits (except for WHR) and at 163 to approximately 167 cM on chromosome 5 for BMI and BSA, with the maximum logarithm of the odds ratio score of 3.12 (empirical p value, 0.002) for BSA on chromosome 2. Use of the bivariate linkage model yielded an additional peak (logarithm of the odds ratio = 3.25, empirical p value, 0.002) at 25 cM on chromosome 7 for the pair of BMI and BSA. DISCUSSION: The evidence for linkage on chromosomes 2q36-37 and 5q36 is supported both by univariate and bivariate analysis, and an additional linkage peak at 7p15 was identified by the bivariate model. This suggests that use of the bivariate model provides additional information to identify linkage of genes responsible for obesity-related traits.

Hypertension genes are genetic markers for insulin sensitivity and resistance.

Insulin resistance is a determinant of blood pressure variation and risk factor for hypertension. Because insulin resistance and blood pressure cosegregate in Mexican American families, we thus investigated the association between variations in 9 previously reported hypertension genes (ACE, AGT, AGTRI, ADDI, NPPA, ADDRB2, SCNN1A, GNB3, and NOS3) and insulin resistance. Families were ascertained via a coronary artery disease proband in the Mexican American Coronary Artery Disease Project. Individuals from 100 Mexican American families (n=656) were genotyped for 14 polymorphisms in the 9 genes and all adult offspring and offspring spouses were phenotyped for insulin sensitivity by hyperinsulinemic euglycemic clamp (n=449). AGT M235T and NOS3 A(-922)G and E298D polymorphisms were significantly associated with insulin sensitivity (P=0.018, 0.036, 0.039) but were not significant after adjusting for body mass index. ADD1 G460W was associated with insulin sensitivity only after adjusting for body mass index. The NPPA T2238C and SCNN1A A663T were associated with decreased fasting insulin levels after adjusting for body mass index (P=0.015 and 0.028). In conclusion, AGT, NOS3, NPPA, ADRB2, ADD1, and SCNN1A may well be genetic markers for insulin resistance, and adiposity was a potential modifier for only some gene/trait combinations. Our data support the hypothesis that genes in the blood pressure pathway may play a role in insulin resistance in Mexican Americans.

A genome-wide scan for carotid artery intima-media thickness: the Mexican-American Coronary Artery Disease family study.

BACKGROUND AND PURPOSE: Carotid artery intima-media thickness (CIMT), a subclinical measure of atherosclerosis, is associated with coronary artery disease (CAD), and stroke. CIMT is also an important predictor of clinical cardiovascular events. To systematically identify the genetic determinants of CIMT, we performed a genome-wide scan using data from 91 2-generation Mexican American families ascertained via a parent with CAD diagnosed. METHODS: CIMT was measured in 274 adult offspring (mean age, 34.6 years) using high-resolution B-mode ultrasound; 413 subjects, including adult offspring and their parents, were genotyped using Marshfield screen set 12 (380 microsatellite markers at approximately 10-cM interval). Heritability was estimated using the variance component approach implemented in SOLAR. Linkage analyses were performed using both the sib-pair regression approach and the variance component approach. RESULTS: The estimated heritability was 0.68, 0.45, and 0.40 for unadjusted, gender- and age-adjusted, and multivariate-adjusted CIMT, respectively. The strongest evidence of linkage was found on chromosome 2 at D2S2944 (logarithm of the odds [LOD]=3.08). Other suggestive linkages were also found on chromosome 6 at D6S1022 to D6S2410 (LOD=2.21) and chromosome 13 at D13S796 to D13S895 (LOD=1.34). CONCLUSIONS: These results show that there is a strong genetic effect on CIMT in these Mexican American CAD families. The linkage peak on chromosome 2 suggests that there is a gene (or genes) at this chromosome location influencing CIMT.

Coronary vasomotor abnormalities in insulin-resistant individuals.

BACKGROUND: Insulin resistance is a metabolic spectrum that progresses from hyperinsulinemia to the metabolic syndrome, impaired glucose tolerance, and finally type 2 diabetes mellitus. It is unclear when vascular abnormalities begin in this spectrum of metabolic effects. OBJECTIVE: To evaluate the association of insulin resistance with the presence and reversibility of coronary vasomotor abnormalities in young adults at low cardiovascular risk. DESIGN: Cross-sectional study followed by prospective, open-label treatment study. SETTING: University hospital. PATIENTS: 50 insulin-resistant and 22 insulin-sensitive, age-matched Mexican-American participants without glucose intolerance or traditional risk factors for or evidence of coronary artery disease. INTERVENTION: 3 months of thiazolidinedione therapy for 25 insulin-resistant patients. MEASUREMENTS: Glucose infusion rate in response to insulin infusion was used to define insulin resistance (glucose infusion rate < or = 4.00 mg/kg of body weight per minute [range, 0.90 to 3.96 mg/kg per minute]) and insulin sensitivity (glucose infusion rate > or = 7.50 mg/kg per minute [range, 7.52 to 13.92 mg/kg per minute]). Myocardial blood flow was measured by using positron emission tomography at rest, during cold pressor test (largely endothelium-dependent), and after dipyridamole administration (largely vascular smooth muscle-dependent). RESULTS: Myocardial blood flow responses to dipyridamole were similar in the insulin-sensitive and insulin-resistant groups. However, myocardial blood flow response to cold pressor test increased by 47.6% from resting values in insulin-sensitive patients and by 14.4% in insulin-resistant patients. During thiazolidinedione therapy in a subgroup of insulin-resistant patients, insulin sensitivity improved, fasting plasma insulin levels decreased, and myocardial blood flow responses to cold pressor test normalized. LIMITATIONS: The study was not randomized, and it included only 1 ethnic group. CONCLUSIONS: Insulin-resistant patients who do not have hypercholesterolemia or hypertension and do not smoke manifest coronary vasomotor abnormalities. Insulin-sensitizing thiazolidinedione therapy normalized these abnormalities. These results suggest an association between insulin resistance and abnormal coronary vasomotor function, a relationship that requires confirmation in larger studies.