Laboratory diagnosis of Mycoplasma pneumoniae infections: data analysis from clinical practice

An etiological diagnosis of respiratory infections caused by Mycoplasma pneumoniae is particularly challenging due to the lack of a definite standard test. This study aimed to analyse the correlation and combination of diagnostic results obtained from direct and indirect assays (Mycoplasma pneumoniae DNA by PCR and serology) in use at a first level diagnostic laboratory. Samples from patients with respiratory infections tested for M. pneumoniae during routine clinical practice were retrospectively analysed. In pediatric patients <15 years old, we documented a significantly higher proportion of IgM positive results (23.6% versus 3.9% in ≥15-year-old patients, p<0.0001) but a lower IgM specificity (false positive IgM 34.8% versus 12.2% in ≥15 years old patients, p 0.01), as verified by seroconversion. A small percentage (4%) of respiratory samples were positive for M. pneumoniae DNA regardless of age and type of sample. Assuming IgM positivity as the reference standard, PCR showed a total lack of sensitivity in patients <15 years old and 20% sensitivity in children <15 years old; specificity was 95% in both age groups. Agreement between PCR and IgM serology was slight (Cohen's kappa 0.09). According to our data, no single diagnostic test could be considered optimal for M. pneumoniae detection and improved assays are required.

Sheep (Ovis aries) Macrophage Migration Inhibitory Factor: molecular cloning, characterization, tissue distribution and expression in the ewe reproductive tract and in the placenta

Macrophage Migration Inhibitory Factor (MIF) is a pivotal regulator of innate and acquired immunity affecting the response and behavior of macrophages and lymphocytes. However, a number of studies indicated wider physiological functions for this cytokine to include key-roles in reproductive biology. The present study was designed to clone the coding sequence of sheep MIF, to examine the characteristics of the protein in vitro, and to evaluate its expression in sheep tissues and in the ewe reproductive tract in vivo. Ovine MIF cDNA consisted of 348 nucleotides encoding a 115 amino acids protein with an estimated molecular mass of 12,343 Da and an isoelectric point of 7.68. Sheep MIF shared high amino acid identity with the other mammalian MIF family members and showed parallel functions to human MIF, displaying enzymatic oxoreductase activity and inducing monocyte transmigration. Expression studies detected a MIF transcript in all the sheep tissues examined. Among reproductive tissues, MIF mRNA and protein were detected in the ovary, oviduct, uterus and placenta. These results indicate that sheep MIF shares crucial features with other MIF family members and delineate its potential involvement in several aspects of ovine physiology.

Establishment and characterization of murine small cell lung carcinoma cell lines derived from HPV-16 E6/E7 transgenic mice

We have established two murine cell lines derived from Small Cell Lung Carcinomas (SCLCs) developed by HPV-E6/E7 transgenic mice. These cells named PPAP-9 and PPAP-10 were isolated from mice bearing tumors, 9 and 10 months old, respectively. The cells, 5 microm in diameter, express HPV oncoproteins and sustain tumor formation after subcutaneous injection in syngenic mice. A detailed analysis indicated the epithelial origin and the neuroendocrine differentiation of these cells. We showed by confocal immunofluorescence the expression of the epithelial marker cytokeratin 5, whose gene promoter was used to direct the expression of HPV E6/E. Cells express several neuroendocrine markers such as CGRP, MAP-2, Ash1, CgrA, Scg2. The neuroendocrine differentiation of these cells was further confirmed by electron microscopy demonstrating neuropeptides secreting granules in their cytoplasm. Furthermore, in agreement with the altered expression observed in the majority of human SCLC we showed in these cells the absence of both p53 and pRB and a dramatic reduction in the expression of Caveolin-1.