Highly sensitive detection of HPV-DNA in paraffin sections of human oral carcinomas.

Background: Although human papillomavirus (HPV) infection has been shown to be a significant carcinogen in cervical squamous cell carcinoma (SCC), its significance in oral SCC remains unclear.

Methods: We developed highly sensitive detection methods for HPV to elucidate the prevalence and localization of HPV in paraffin sections from human oral SCC using modified in situ polymerase chain reaction (PCR) and in situ hybridization AT tailing (ISH-AT). Analyses revealed a high prevalence of several HPV types (HPV-16, -18, -22, -38 and -70) under optimal conditions.

Root nodule Bradyrhizobium spp. harbor tfdAalpha and cadA, homologous with genes encoding 2,4-dichlorophenoxyacetic acid-degrading proteins.

The distribution of tfdAalpha and cadA, genes encoding 2,4-dichlorophenoxyacetate (2,4-D)-degrading proteins which are characteristic of the 2,4-D-degrading Bradyrhizobium sp. isolated from pristine environments, was examined by PCR and Southern hybridization in several Bradyrhizobium strains including type strains of Bradyrhizobium japonicum USDA110 and Bradyrhizobium elkanii USDA94, in phylogenetically closely related Agromonas oligotrophica and Rhodopseudomonas palustris, and in 2,4-D-degrading Sphingomonas strains. All strains showed positive signals for tfdAalpha, and its phylogenetic tree was congruent with that of 16S rRNA genes in alpha-Proteobacteria, indicating evolution of tfdAalpha without horizontal gene transfer.

Detection of HPV in Japanese and Chinese oral carcinomas by in situ PCR.

Human papillomavirus (HPV) is established as the cause of almost 100% of cervical carcinomas. However, the association of HPV with oral squamous cell carcinomas (SCCs) is less well understood. We examined the prevalence of HPV in oral SCCs in samples of Japanese and Chinese populations.

A novel immunohistochemical technique for the detection of human oral carcinomas transplanted in nude mice using mouse monoclonal antibodies.

We have developed a new immunostaining technique specifically for the detection of human tumors transplanted into nude mice using mouse monoclonal antibodies (MoAbs) produced in our laboratory. The formation of a molecular complex consisting of three components (mouse MoAb or hybridoma supernatant, biotin-labeled anti-mouse immunoglobulins, and normal nude mouse serum) markedly reduced background staining and enhanced specific reaction with the transplanted tumors in nude mice. When MoAb production by electrofusion was screened with this new method, the incidence of hybridoma supernatant reactive with sections of transplanted tumor was 2.

Cytoplasmic crystalloids in the periodontal tissue of beige mice.

The periodontal tissue of beige mice has been examined by electron microscopy. Specimens of the periodontal tissue from the right mandibular first molars of 10 male beige (bg/bg) and 5 male non-beige (bg/+, controls) mice, were fixed in a mixture of glutaraldehyde and paraformaldehyde, and then decalcified in EDTA. After fixation in osmium tetroxide, the specimens were dehydrated and embedded in epon resin.