Genetic relationships between clinical isolates of Streptococcus pneumoniae, Streptococcus oralis, and Streptococcus mitis: characterization of "Atypical" pneumococci and organisms allied to S. mitis harboring S. pneumoniae virulence factor-encoding genes.

The oral streptococcal group (mitis phylogenetic group) currently consists of nine recognized species, although the group has been traditionally difficult to classify, with frequent changes in nomenclature over the years. The pneumococcus (Streptococcus pneumoniae), an important human pathogen, is traditionally distinguished from the most closely related oral streptococcal species Streptococcus mitis and Streptococcus oralis on the basis of three differentiating characteristics: optochin susceptibility, bile solubility, and agglutination with antipneumococcal polysaccharide capsule antibodies. However, there are many reports in the literature of pneumococci lacking one or more of these defining characteristics.

Population biology of Streptococcus pneumoniae isolated from oropharyngeal carriage and invasive disease.

The population structure of Streptococcus pneumoniae in a sample of 134 carried antibiotic-susceptible isolates, and 53 resistant and susceptible invasive isolates, was examined using a DNA-based version of multilocus enzyme electrophoresis: multilocus restriction typing (MLRT). This involved RFLP analysis of PCR products generated from nine loci of housekeeping genes located around the pneumococcal chromosome. The combination of alleles at each of the nine loci gave an allelic profile or restriction type (RT).

Semi-quantitative analysis of interleukin-1 alpha, interleukin-6 and interleukin-8 mRNA expression by human thyrocytes.

It has been suggested that the thyroid itself may contribute to the inflammatory process observed in autoimmune thyroiditis by releasing the cytokines interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8), but studies of cytokine gene expression in thyrocytes have been limited and conflicting. A semi-quantitative reverse transcription-PCR technique has been used to investigate the expression of IL-1 alpha, IL-6 and IL-8 mRNA in the human thyroid cell line HTori3 and in cultures of primary human thyroid follicular cells (TFCs). Cytokine mRNA levels were examined over a 24-h period, and the modulatory effects of exogenous IL-1 alpha, interferon-gamma (IFN-gamma) and TSH investigated.

Lack of association between a polymorphism in the coding region of the thyrotropin receptor gene and Graves' disease.

Using a combination of polymerase chain reaction amplification, oligonucleotide mismatch hybridization, and direct sequencing, we analyzed the distribution of a recently described TSH receptor gene polymorphism in 88 patients with Graves' disease but no clinically apparent eye disease, 53 patients with Graves' disease and associated ophthalmopathy, 39 patients with autoimmune hypothyroidism, and 156 control subjects. No significant difference in the distribution of this polymorphism was found between either group of Graves' patients, the hypothyroid patients, or the control group. These results suggest that this coding region polymorphism is not associated with the occurrence of Graves' disease or Graves' ophthalmopathy.

Analysis of cytokine gene expression in Graves' disease and multinodular goiter.

Cytokines have a central role in the generation of an autoimmune response and can directly affect the target organ. In Graves' disease, both the infiltrating mononuclear cells and the thyroid follicular cells produce certain cytokines, but the relative contribution of each is unclear, and there are conflicting data on the exact profile of cytokines expressed within the thyroid. To clarify these issues, we used the method of reverse transcription-polymerase chain reaction amplification to analyze cytokine gene expression by intrathyroidal lymphocytes (ITL) and purified thyroid follicular cells (TFC) from six patients with Graves' disease.