Respiratory syncytial virus (RSV) is the major pathogen responsible for acute bronchiolitis in infancy. However, evaluation of the relative importance of rhinovirus or multiple viral infections has been hampered by the lack of sensitive diagnostic methodologies. Therefore, in this study we used the reverse transcription-polymerase chain reaction for 11 respiratory pathogens to assess the etiology in infants with acute bronchiolitis and correlate it with clinical characteristics of the disease. Viruses were detected in 73.7% of patients. RSV was identified in 72.4% of virologically confirmed cases, rhinovirus in 29%, whereas multiple infections represented 19.5% of cases, most of which (69%) were combinations of rhinovirus with RSV. In a logistic regression model controlling for age, sex, birth weight, presence of fever, and day of disease on admission, the presence of rhinovirus was found to increase by approximately five-fold, the risk for severe disease. Multiple pathogens had a similar trend in the univariate analysis, which was eliminated in the multivariate model. Multiple virus cases were admitted to the hospital later in the course of their disease than unique pathogen cases, suggesting successive infections. In conclusion, rhinovirus is second only to RSV as a causative agent of bronchiolitis and is associated with more severe disease. The presence of more than one pathogen may influence the natural history of acute bronchiolitis.

The high prevalence of viral and mixed viral-bacterial infections supports the notion that the presence of a virus, acting either as a direct or an indirect pathogen, may be the rule rather than the exception in the development of CAP in school-age children requiring hospitalization.

The disturbance of apoptosis molecular signaling pathways is involved in carcinogenesis. BCL2 family of proteins is the hallmark of apoptosis regulation. In the last decade, new members of BCL2 gene family were discovered and cloned and were found to be differentially expressed in many types of cancer. BCL2 protein family, through its role in regulation of apoptotic pathways, is possibly related to cancer pathophysiology and resistance to conventional chemotherapy. It is well known that leukemias are haematopoietic malignancies characterized by biological diversity, varied cytogenetics, different immunophenotype profiles, and diverse outcome. Current research focuses on the prognostic impact and specific role of these proteins in the pathogenesis of leukemias. The understanding of the molecular pathways that participate in the biology of leukemias may lead to the design of new therapies which may improve patients' survival. In the present paper, we describe current knowledge on the role of BCL2 apoptosis regulator proteins in acute and chronic leukemias.

PCR revealed the presence of hMPV in 16% of bronchiolitis cases, whereas respiratory syncytial virus (RSV; 67.9%) was the most frequently encountered viral pathogen. hMPV was identified either as a unique viral pathogen or co-existed with RSV, with whom they shared a similar seasonal distribution. There were no differences in disease characteristics, either clinical or laboratory, between bronchiolitis cases where hMPV was present and those caused by RSV or other viral pathogens. These findings suggest that hMPV is a common and important causative agent in infants with bronchiolitis, with clinical characteristics similar to that of RSV.

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Respiratory syncytial virus (RSV) subtypes A and B are present either simultaneously or alternate during yearly epidemics. It is still not clear whether clinical severity of acute bronchiolitis differs between the two subtypes. Reverse transcription polymerase chain reaction was used to subtype RSV in previously healthy infants hospitalized with RSV bronchiolitis during a winter epidemic. A severity index based on heart rate, respiratory rate, wheezing, difficulty in feeding and oxygen saturation was calculated upon admission. Infants infected with RSV subtype-A were found to have a significantly higher (more severe) clinical score than those infected with RSV-B. There was no statistically significant difference in duration of hospitalization or need of intensive care. Boys and infants younger than 3 months of age were also more severely affected than girls or older infants, respectively. These results support the notion that RSV-A-induced bronchiolitis is more severe than RSV-B-induced one, in agreement with the majority of previously published studies.

Background: Human rhinoviruses (RV), the most common triggers of acute asthma exacerbations, are considered not cytotoxic to the bronchial epithelium. Recent observations, however, have questioned this knowledge. The aim of this study was to evaluate the ability of RV to induce epithelial cytotoxicity and affect epithelial repair in-vitro.

Under the influence of an atopic environment, the epithelial inflammatory response to RV is down-regulated, associated with increased viral proliferation and augmented cell damage, while TGF is up-regulated. These changes may help explain the propensity of atopic asthmatic individuals to develop lower airway symptoms after respiratory infections and indicate a mechanism through which viral infections may promote airway remodelling.