The DR3(w18),DQw4 haplotype differs from DR3(w17),DQw2 haplotypes at multiple class II loci

The polymorphism of HLA class II molecules in man is particularly evident when comparisons between population groups are made. This study describes a DR3 haplotype commonly present in the American black population. Unlike the Northern European population, in which almost all DR3 individuals are DQw2, approximately 50% of DR3-positive American blacks express a DQw4 allelic product. This study characterizes the DR subregion of that haplotype. cDNA sequence analysis has revealed a DR beta gene which differs at several positions from previously described DR3 beta 1 genes. It is postulated that a gene-conversion-like event with a DRw52 beta gene as donor has generated some of these differences. The haplotype carries a DRw52a allele as defined by oligonucleotide hybridization studies. DNA restriction fragment analysis using a family and several unrelated individuals has allowed us to identify DR alpha and beta fragments associated with the DR3(w18),DQw4 haplotype. The most striking observation is that the DR3(w18),DQw4 haplotype differs from DR3(w17),DQw2 haplotypes at multiple class II loci. Several genetic mechanisms including reciprocal recombination, gene conversion, and point mutation were involved in generating the differences between these haplotypes. Once established, the DR3(w18),DQw4 haplotype appears to be relatively stable in the population.     

Bronchial epithelial cells produce lung fibroblast chemotactic factor: fibronectin

The interaction between the epithelial cells and the subjacent mesenchymal cells in the airway is thought to play a major role during tissue repair after airway injury and lung morphogenesis. To evaluate this interaction, we cultured human lung fibroblasts, and bovine and human bronchial epithelial cells, and determined that bronchial epithelial cell-conditioned medium has a chemotactic activity for lung fibroblasts. This activity had the characteristics of protein: it was nondialyzable, heat-labile, pepsin-labile, acid-stable, and lipid-inextractable. Molecular sieve chromatography on Sephadex G-150 and affinity chromatography on gelatin-Sepharose revealed that there was one peak of chemotactic activity in high molecular weight range, which bound to gelatin, thus suggesting that the chemotactic factor might be fibronectin. Production and secretion of fibronectin into the culture media were demonstrated by biosynthetic incorporation of radioactive amino acid into fibronectin followed by immunoprecipitation on SDS-PAGE and autoradiography. Release into the culture medium was confirmed by ELISA. The identity of fibronectin as the chemotactic activity was confirmed by the addition of antifibronectin antibody to the conditioned medium, which inhibited chemotaxis in dose-dependent manner. Thus, bronchial epithelial cells produce fibronectin which can function as a chemotactic factor for lung fibroblasts. This production of fibronectin by bronchial epithelial cells may play an important role in regulating interaction between the bronchial epithelial cells that line the lumenal surface of the bronchial epithelial wall and the mesenchymal fibroblasts that underlie the bronchial epithelial basement membrane.     

Patients' attitudes about rapid oral HIV screening in an urban, free dental clinic

The 2006 Centers for Disease Control recommendations for routine HIV screening in all health care settings could include dental clinics an important testing venue. However, little is known about patients' attitudes regarding the routine use of rapid oral HIV screening at an urban free dental clinic. This pilot study seeks to evaluate the patient perspective on rapid HIV screening in this setting. In June 2007, patients at a free dental clinic in Kansas City, Missouri, were provided an attitude assessment survey prior to their dental visit. This dental clinic serves a diverse patient population consisting of approximately 37% white, 47% black, 6% Hispanic, 4% Asian, and 1% Native American uninsured patients. Results were analyzed for acceptance of testing and potential barriers. Of the 150 respondents, 73% reported they would be willing to take a free rapid HIV screening test during their dental visit. Overall, 91% of Hispanics, 79% of Caucasians, and 73% of African American patients reported they would be willing to be screened. Patients with a history of multiple prior screening tests for HIV were more likely to agree to oral rapid HIV screening in the dental clinic. The majority (62%) reported that it did not matter who provided them with the screening result, although some (37%) preferred their dentist above any other provider. Low self-perception of risk (37%) and having already received screening elsewhere (24%) were the main reasons for not accepting a free, rapid HIV screening. Overall, dental clinic patients widely accepted the offer of rapid oral HIV screening. Rapid HIV screening in the dental clinic setting is a viable option to increase the number of individuals who know their HIV status.