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Robertino Mera

Publications and source records attributed to Robertino Mera.

9 recordsLinked to original sources
PubMed2006

Interleukin-1beta and interleukin-1 receptor antagonist gene polymorphisms and gastric cancer: a meta-analysis.

BACKGROUND: Polymorphisms of interleukin-1B (IL1B) and its receptor antagonist (IL1RN) genes have been inconsistently associated with gastric cancer risk. We examined these associations by performing meta-analyses. MATERIALS AND METHODS: Twenty-five studies testing the association between IL1B and/or IL1RN gene polymorphisms and gastric cancer were examined: 14 studies of IL1B-511, 14 studies of IL1B-31, 8 studies of IL1B+3954, and 23 studies of IL1RN. Overall and ethnicity-specific summary odds ratios and corresponding 95% confidence intervals for gastric cancer associated with these polymorphisms were estimated using fixed- and random-effects models. Heterogeneity and publication bias were evaluated. RESULTS: IL1B-511T and IL1RN*2 were associated with gastric cancer risk in Caucasians, but not in Asians. For IL1B-511T, the association in Caucasians was stronger when intestinal-subtype and noncardia gastric cancer cases were examined. A nonsignificant trend was observed between IL1B-31C and gastric cancer in Caucasians. No significant association of IL1B+3954T and gastric cancer risk was detected. Studies with better methodologic characteristics reported stronger effects. There was no evidence of publication bias. CONCLUSION: IL1B-511T is associated with gastric cancer susceptibility in Caucasians. The meta-analyses suggest that the conflicting results among studies may be explained by variation in allele frequencies among the ethnic groups and variation in tumor types, as well as by the methodologic quality of the studies.

Gene Frequency↗
PubMed2005

Predicting the future Streptococcus pneumoniae resistance landscape.

Streptococcus pneumoniae resistance to antibiotics is considered a public health problem, and yet the link between year-to-year increases in resistance and antimicrobial consumption has been difficult to prove. Mathematical models and epidemiological studies have shown that there is no linear relationship between consumption and resistance, and that increasing resistance is caused by the removal of susceptible strains from the population. Pneumococcal conjugate vaccine has also been shown to have an impact over resistance. A model that relates resistance with the cumulative consumption of antibiotics over time explains low resistance rates in countries such as Germany and plateaus in resistance in the US. Moreover, understanding this temporal relationship allows us to predict that if the cumulative consumption stabilizes so will the resistance rates.

Anti-Infective Agents↗
PubMed2004

13C-urea breath test for Helicobacter pylori in young children: cut-off point determination by finite mixture model.

The 13C-urea breath test (UBT) is currently regarded as one of the most important noninvasive diagnostic methods for detecting Helicobacter pylori (H. pylori) infection in adults and children. However, for infants and young children, the standard for UBT interpretation has not been validated, and its reliability has not been established for diagnosing H. pylori infection in this group. The primary outcome data from UBT consist of mixture data, which come from subjects whose H. pylori infection classifications are unconfirmed. In this paper, we propose the finite mixture distribution method to identify a reliable UBT cut-off value in a large baseline sample in which gastric biopsy is not available to confirm the H. pylori infection in younger children. Maximum likelihood estimators of the parameters in the mixture model were obtained using an expectation maximization (EM) algorithm. The standard deviation of the cut-off point was estimated by bootstrap methods. We applied the same analytical methods to the UBT results yielded from the follow up, as well as the overall UBT results in the longitudinal cohort data. The cut-off points from those UBT data sets are similar. The advantage of the finite mixture model is that it may be used to calculate sensitivity and specificity in the absence of other diagnostic tests.

Breath Tests↗
PubMed2003

Analyzing data in which the outcome is time to an event part II: The presence of multiple covariates.

In this article, the second of a series on the analysis of time to event data, we address the case in which multiple predictors (covariates) that may influence the time to an event are taken into account. The hazard function is introduced, and is given in a form useful for assessing the impact of multiple covariates on time to an event. Methods for the assessment of model fitting are also discussed and an example with cancer survival as outcome with the presence or absence of multiple genes as covariates is presented.

Humans↗
PubMed2003

Impact of Helicobacter pylori infection on growth of children: a prospective cohort study.

OBJECTIVE: The aim of this study was to prospectively follow a cohort of children without Helicobacter pylori infection and to compare growth velocity in the children who become infected during follow-up with that of children who remained infection-free. METHODS: Three hundred forty-seven children in general good health, aged 12 to 60 months, who tested negative for H. pylori by the 13C-urea breath test, from three daycare centers in a lower-middle class borough of Cali, Colombia, were monitored for 2.5 years. Anthropometric measurements were performed every 2 months and breath tests every 4 months. Linear mixed models were used to analyze growth velocity in relation to onset of H. pylori infection. RESULTS: One hundred five (30.3%) children who were uninfected at the start of the study became infected during follow-up. Growth velocity in infected children was reduced by 0.042 +/- 0.014 cm/mo (P = 0.003) (approximately 0.5 cm/yr) after adjusting for age. The rate of deceleration in growth velocity was relatively constant over time. CONCLUSIONS: Among these lower-middle class children aged 12 to 60 months from a population with high prevalence of H. pylori infection, a new and sustained infection was followed by significant growth retardation.

Body Height↗