Streptococcus pneumoniae isolates from middle ear fluid and nasopharynx of children with acute otitis media exhibit phase variation.

Pneumococcal phase variation of 37 middle ear and 31 nasopharyngeal isolates obtained from children with acute otitis media was examined in the absence of intervening culture. The fraction of the opaque colonies was significantly higher in middle ear isolates than in nasopharyngeal isolates. The difference is probably the result of the pneumococci adapting to differential selective environments.

[Implication of vascular endothelial growth factor (VEGF) in human head and neck cancer].

PURPOSE: Metastatic activity is one parameter indicating the malignancy of tumor cells. Angiogenesis has now been extensively studied to clarify the mechanisms of tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is an angiogenic cytokine expressed by many human and animal tumors. We studied the role of VEGF in tumor growth by transfecting the VEGF gene into tumor cells and analyzing the survival period of nude mice implanted with these transfected tumor cells. MATERIALS AND METHODS: Cell line: The tumor cell line, OKK-LN, was established from human maxillary squamous cell carcinoma and used in this study. The tumor cells did not produce VEGF in the culture supernatant. Transfection: OKK-LN cells were stably transfected with sense VEGF165 cDNA or with the vector alone. The full-length VEGF165 cDNA was cloned into an expression vector (pCIneo). The DNA transfection was performed by the lipofection method, and the limiting dilution method was used for cloning. ELISA was used to measure VEGF in the culture supernatant. As a control, OKK-LN cells were transfected with the vector alone without VEGF (OKK-LN/pCIneo). The tumor cells were subcutaneously injected into nude mice (Balb/c nu/nu, 6W), and the survival period and tumor volume were analyzed. Effects of angio-suppressive agent, TNP-470, and anti-VEGF antibody on tumor growth and angiogenesis: TNP-470 (supplied by Takeda Pharmaceutical Co., Ltd.) and monoclonal anti-human VEGF antibodies were intraperitoneally administered to mice implanted with tumor cells once a week and twice a week for 5 weeks, respectively. The effects of TNP-470 and anti-VEGF antibodies were analyzed by examining tumor size and survival rate and immunohistologically using CD31 monoclonal antibody. RESULTS: Tumor cells transfected with sense VEGF 165 cDNA (referred to as OKK-LN/pCIneo VEGF ) produced VEGF in the supernatant permanently, confirming the establishment of a VEGF-producing human cancer cell line. We observed marked tumor growth and a shortened survival period by nine days in the OKK-LN/pCIneo-VEGF group, compared to the control group. The administration of TNP-470 and anti-VEGF antibody significantly suppressed tumor growth. The immunohistological study showed the significant suppression of a number of tumor vessels in anti-VEGF antibody-administered mice. CONCLUSION: Our data strongly suggests that VEGF plays an important role in tumor growth and that treatment by anti-VEGF antibody may be a promising strategy against head and neck cancers.

[Roles of beta-catenin overexpression and adenomatous polyposis coli mutation in head and neck cancer].

Beta-catenin is an undercoat protein of cadherin, a cellular adhesion molecule. Beta-catenin also functions as a transcriptional activator downstream of the Wnt signaling pathway. Intracellular beta-catenin is regulated by the formation of a complex with APC (adenomatous polyposis coli) protein. The activation of this pathway by stabilization with beta-catenin has been shown to be an important step in the development of colorectal carcinoma, which is mainly caused by inactivating mutations in the APC tumor suppressor gene or by activating mutations in exon 3 of the beta-catenin gene. This study was conducted to clarify the contribution of beta-catenin accumulation and the mutation of the beta-catenin gene to the carcinogenesis of head and neck cancer. Beta-catenin accumulation was examined immunohistochemically in 49 frozen or formalin-fixed, paraffin-embedded samples of head and neck tumors. We also performed a direct sequence analysis of APC and beta-catenin to examine the cause of beta-catenin accumulation. Genomic DNA was extracted and purified from fresh tissue samples of head and neck cancers. We examined the APC mutation cluster region in 15 samples and analyzed beta-catenin exon 3 mutations in 31 cases. Twelve out of 49 (24.5%) cases exhibited beta-catenin accumulation in our histochemical study. The 5 year survival rate was 0% in the beta-catenin accumulation group, compared to 50% in the non-accumulation group, (p < 0.01). This finding strongly suggests that beta-catenin may play an important role in the carcinogenesis or progression of head and neck cancer. One of the 15 cases exhibited an APC missense mutation that led to the replacement of amino acids; this case died in 12 months. Regarding the beta-catein mutation, non of the 31 samples exhibited a gene mutation in beta-catenin exon 3. Thus, the rate of APC and beta-catenin mutation in head and neck cancer may be very low.