Zero-inflated Poisson regression models for QTL mapping applied to tick-resistance in a Gyr x Holstein F2 population

Nowadays, an important and interesting alternative in the control of tick-infestation in cattle is to select resistant animals, and identify the respective quantitative trait loci (QTLs) and DNA markers, for posterior use in breeding programs. The number of ticks/animal is characterized as a discrete-counting trait, which could potentially follow Poisson distribution. However, in the case of an excess of zeros, due to the occurrence of several noninfected animals, zero-inflated Poisson and generalized zero-inflated distribution (GZIP) may provide a better description of the data. Thus, the objective here was to compare through simulation, Poisson and ZIP models (simple and generalized) with classical approaches, for QTL mapping with counting phenotypes under different scenarios, and to apply these approaches to a QTL study of tick resistance in an F2 cattle (Gyr x Holstein) population. It was concluded that, when working with zero-inflated data, it is recommendable to use the generalized and simple ZIP model for analysis. On the other hand, when working with data with zeros, but not zero-inflated, the Poisson model or a data-transformation-approach, such as square-root or Box-Cox transformation, are applicable.

Sepse neonatal precoce: níveis de citocinas no sangue de cordão umbilical no diagnóstico e durante o tratamento / Early-onset neonatal sepsis: cord blood cytokine levels at diagnosis and during treatment

OBJETIVO: Avaliar parâmetros clínicos, laboratoriais e citocinas séricas em 55 neonatos que desenvolveram sepse precoce. MÉTODOS: Avaliamos os parâmetros clínicos dos neonatos relacionados com sepse precoce. No dia do diagnóstico de sepse e 48 horas após, foram realizados o leucograma diferencial e a dosagem de proteína C reativa e glicemia. As citocinas IL-1β, IL-10, IL-6 e TNF-α foram determinadas no sangue do cordão, no dia do diagnóstico de sepse, 48 e 96 horas após o início do tratamento. RESULTADOS: O tempo de internação dos neonatos foi inversamente proporcional ao peso no nascimento. Os parâmetros clínicos foram variados, especialmente a temperatura corpórea. Alterações de glicemia foram frequentes, principalmente a hipoglicemia. A alteração de hemograma mais prevalente foi a leucopenia, devido principalmente à neutropenia. Os níveis de proteína C reativa se mostraram correlacionados com o índice neutrofílico. Observamos uma correlação positiva entre os níveis de TNF-α e IL-10 entre o curso da sepse precoce e os níveis observados no cordão umbilical. CONCLUSÕES: As alterações clínicas e laboratoriais entre os neonatos com sepse são variadas. Neonatos que apresentam elevações no padrão de citocinas no momento do parto permanecem com seus níveis elevados durante o processo infeccioso.

OBJECTIVE: To assess clinical and laboratory parameters and serum cytokine levels in 55 neonates who developed early-onset sepsis. METHODS: Clinical parameters associated with early-onset neonatal sepsis were assessed. White blood cell differential and serum C-reactive protein and glucose levels were measured upon diagnosis of sepsis and 48 hours later. IL-1β, IL-10, IL-6, and TNF-α levels were measured in cord blood samples obtained on the day of diagnosis and from samples collected 48 and 96 hours after treatment onset. RESULTS: Among newborns with early-onset sepsis, the length of hospital stay was inversely correlated with birth weight. Clinical parameters varied widely, especially body temperature. Blood glucose changes - particularly hypoglycemia - were common. Leukopenia, usually due to neutropenia, was the most prevalent change in blood cell count. C-reactive protein levels correlated with the immature-to-total neutrophil ratio. Serum TNF-α and IL-10 levels measured early in the course of sepsis were positively correlated with those detected in cord blood. CONCLUSIONS: Clinical and laboratory parameters varied widely among neonates with sepsis in this sample. In neonates who presented with increased cytokine levels at birth, this abnormality persisted throughout the infectious process.

Human toxocariasis: a seroepidemiological survey in schoolchildren of Sorocaba, Brazil

A seroepidemiological survey for toxocariasis, among 180 schoolchildren of the public schools of Sorocaba City, state of São Paulo, Brazil, was carried out from August 2000 to July 2001. ELISA test was performed using excretory and secretory antigens for the detection of IgG anti-Toxocara antibodies. Information regarding the children was obtained from the parents or legal guardians. The results showed that the mean age was 5.4 ± 1.4 years, the infection coefficient (IC) was 38.3 and the infection risk was higher among the children living in the city outskirts (IC = 47.4) where the socioeconomic conditions were worse than in the central region of the city (IC = 11.1). There was an association between higher frequency of seroreactivity in the ELISA test and the condition of living in a house with a yard and/or unpaved street. The same was observed in relation to a history of enteroparasitism. There was also an association between a seronegative ELISA test and previous treatment of pet dogs and/or cats with vermifuge. Based on these results, the authors propose that public health programs should include anthelmintic for dogs and cats during the antirabies vaccination campaigns, in order to diminish environmental contamination with Toxocara spp. eggs and consequently human infection.