Engineered Cx26 variants established functional heterotypic Cx26/Cx43 and Cx26/Cx40 gap junction channels.

Gap junction (GJ) channels mediate direct intercellular communication and are composed of two docked hemichannels (connexin oligomers). It is well documented that the docking and formation of GJs are possible only between compatible hemichannels (or connexins). The mechanisms of heterotypic docking compatibility are not fully clear. We aligned the protein sequences of docking-compatible and -incompatible connexins with that of connexin26 (Cx26). We found that two docking hydrogen bond (HB)-forming residues on the second extracellular domain (E2) of Cx26 and their equivalent residues are well conserved within docking-compatible connexins, but different between docking-incompatible connexins. Replacing one or both of these residues of Cx26 into the corresponding residues in the docking incompatible connexins (K168V, N176H or K168V-N176H) increased the formation of morphological and functional heterotypic GJs with connexin43 (Cx43) or connexin40 (Cx40), indicating that these two residues are important for docking incompatibility between Cx26 and these connexins. Our homology structure models predict that both HBs and hydrophobic interactions at the E2 docking interface are important docking mechanisms in heterotypic Cx26 K168V-N176H/Cx43 GJs and probably other docking compatible connexins. Revealing the key residues and mechanisms of heterotypic docking compatibility will assist us in understanding why these putative docking residues are hotspots of disease-linked mutants.

Nontypeable Haemophilus influenzae isolated from intractable acute otitis media internalized into cultured human epithelial cells.

OBJECTIVES: The aim of this study is to examine the internalization of nontypeable Haemophilus influenzae (NTHi) into human epithelial cells. METHODS: Bactericidal assay was applied to examine the effects of antibiotics against cell-adherent NTHi using HEp-2 cells. A trans-well chamber assay was applied to examine the internalization and penetration of NTHi using Detroit562 cells. RESULTS: The adherence of NTHi to HEp-2 cells was noted after 2h of incubation. Azithromycin had a strong bactericidal effect against both cell-associated and non-adherent NTHi, while ceftriaxone did not show bactericidal effects on NTHi adhered to the HEp-2 cells. Three (60.0%) out of five NTHi isolates from the nasopharynx of children with intractable acute otitis media (AOM) internalized into and subsequently penetrated through the epithelial cells at various degrees. Azithromycin had a strong bactericidal effect against the cell-internalized NTHi, while ceftriaxone was bactericidal only against extracellular NTHi. CONCLUSION: The potential of NTHi as the intracellular pathogen may contribute to the persistent existence of this pathogen that result in the prolonged and intractable clinical course of AOM. Azithromycin may be a therapeutically significant antibiotic for patients with prolonged respiratory tract infections due to NTHi.

Pathogenic role of tonsillar lymphocytes in associated with HSP60/65 in Pustulosis palmaris et plantaris.

OBJECTIVE: We aimed to define role of tonsillar lymphocytes (TL) and immune cross-reactivity between bacterial-HSP65 and human-HSP60 in Pustulosis palmaris et plantaris (PPP), an intractable chronic disease characterized with pustules and cornification of palms and soles. METHODS: Two sets of crossover trials were designed by employing SCID mice model. In the first trial, mice were transplanted with tonsillar lymphocytes and skin-grafts from PPP patients (TL group). In the second trial, mice were transplanted with tonsillar lymphocytes from PPP patients and injected with recombinant human HSP60. Control groups were designed for each step. Comparisons were performed for immunologic analyses including infiltration of CD4+ lymphocytes in skin-grafts by immunostaining, and levels of anti-HSP65-IgG and cytokines in mice sera by enzyme-linked immunosorbent assay (ELISA). RESULTS: In TL group, infiltration of CD4+ lymphocytes in skin-grafts were significantly higher than mice transplanted with blood lymphocytes (p<0.05), while anti-HSP65-IgG levels in sera showed non-significant tendency to increase in the TL group. CD4+ cells and anti-HSP65-IgG levels were also well-correlated with each other in TL group (p<0.01). Besides, anti-HSP65-IgG levels were significantly correlated with cytokine levels (IL-6, IFN-gamma) in mice sera (p<0.01). We found strong expression of HSP60 in PPP lesions. Finally, HSP60-stimulation in mice transplanted with TL from PPP patients induced significantly higher anti-HSP65-IgG levels in serum compared to control groups including mice without HSP60-stimulation or peripheral blood lymphocytes-transplanted mice or transplanted with TL from control patients (p<0.05). CONCLUSION: Our results indicate the pathogenic role of TL and immune cross-reaction between human-HSP60 and bacterial-HSP65 in PPP.

Comprehensive loss of heterozygosity analysis and identification of a novel hotspot at 3p21 in salivary gland neoplasms.

OBJECTIVES: We sought to assess loss of heterozygosity (LOH) profiles of 3p, 6q, 8q, 10q, 12q, 13q, and 17p and to identify the tumor suppressor genes involved in salivary gland neoplasms. STUDY DESIGN: LOH analysis was performed using 26 microsatellite markers by polymerase chain reaction-polyacrylamide gel electrophoresis method in 20 benign and 6 malignant salivary gland tumors. RESULTS: Overall, LOH was detected in at least one informative locus in 18 of 20 (90%) of benign tumors and in all of 6 cases of malignant tumors. High LOH frequencies were revealed at the loci D3S1307 (22%, 3p26), D3S966 (41%, 3p21), D6S255 (27%, 6q25), D8S166 (25%, 8q12), D8S199 (21%, 8q24), and D10S1765 (28%, 10q23) in benign tumors, defining the hotspot regions for putative tumor suppressor genes. CONCLUSIONS AND SIGNIFICANCE: The hotspot regions defined by the present study suggest that new tumor suppressor genes related to the development of salivary gland tumors may reside at several chromosomal loci, including loci at 3p, 6q, 8q and 10q.

Identification of a candidate tumor suppressor gene RHOBTB1 located at a novel allelic loss region 10q21 in head and neck cancer.

PURPOSE: Aims of the study are to narrow-down the hotspot region on 10q21 defined by previous genome-wide loss of heterozygosity (LOH) analysis in head and neck squamous cell carcinomas (HNSCC) and to define candidate tumor suppressor genes (TSG) concerned with 10q21. MATERIALS AND METHODS: LOH analysis was carried out with ten polymorphic microsatellite markers. Expression analysis was performed by semi-quantitative RT-PCR, and mutation analysis by PCR and direct sequencing. RESULTS: LOH analysis on 10q21 in 52 HNSCC indicated distinctive and frequent allelic loss at D10S589 (42%). Among flanking genes, we found the RHOBTB1 gene as a candidate TSG, since an intragenic marker demonstrated the highest LOH (44%). Expression analysis revealed down-regulation of RHOBTB1 mRNA in 37% of tumors. Interestingly, all the five tumors that showed decreased expression of RHOBTB1 were accompanied with LOH, supporting the haploinsufficiency and class 2 TSG characteristics of RHOBTB1. No pathogenic mutation of RHOBTB1 was found. Furthermore, another gene within the region, EGR2, was also taken under scope. LOH frequencies around the EGR2 gene were relatively low (23 and 33%). Albeit semi-quantitative expression analysis of EGR2 demonstrated downregulation in 45% of tumor samples, no relation was found between the expression levels and LOH status. CONCLUSION: Frequent allelic loss and decreased expression of RHOBTB1 suggested that this gene has a role in tumorigenesis of a subset of HNSCC.

Subdiaphragmatic abscesses: myths and realities. A report on sixty-two cases.

The main cause (60.8%) of subdiaphragmatic abscesses in a series of 62 patients (of which 46 were males), was found to be hepatobiliary in nature. Radiology proved to be helpful in correct diagnosis (61%), as did ultrasonography (60%). Right sided subdiaphragmatic abscesses were (55/62) 88.7% of the total. Mean abscess volume was 500 ml while culturing efforts were in vain in 32% of the abscess cases (able to be cultured). The incidence of morbidity was (12/62) 19.4% and mortality (3/62) 4.8% in this series, where the treatment was solely through surgical drainage. Though closed drainage using ultrasonic guidance has been popular in the past decade, it has its drawbacks. Open surgical drainage therefore, as a well established mode of treatment, is recommended.