Cyclic mechanical pressure-loading alters epithelial homeostasis in a three-dimensional in vitro oral mucosa model: clinical implications for denture-wearers

Denture-wearing affects the quality and quantity of epithelial cells in the underlying healthy oral mucosa. The physiologic mechanisms, however, are poorly understood. This study aimed to compare histologic changes and cellular responses of an epithelial cell layer to cyclic mechanical pressure-loading mimicking denture-wearing using an organotypic culture system to develop a three-dimensional in vitro oral mucosa model (3DOMM). Primary human oral keratinocytes and fibroblasts were serially grown in a monolayer culture, and cell viability was measured under continuous cyclic mechanical pressure (50 kPa) for 7 days (cycles of 60 min on, 20 s off to degas and inject air). Upon initiation of an air-liquid interface culture for epithelial stratification, the cyclic pressure, set to the mode above mentioned, was applied to the 3DOMMs for 7 days. Paraffin-embedded 3DOMMs were examined histologically and immunohistochemically. In the monolayer culture, the pressure did not affect the viability of oral keratinocytes or fibroblasts. Few histologic changes were observed in the epithelial layer of the control and pressure-loaded 3DOMMs. Immunohistochemical examination, however, revealed a significant decrease in Ki-67 labelling and an increase in filaggrin and involucrin expression in the suprabasal layer of the pressure-loaded 3DOMMs. Pressure-loading attenuated integrin β1 expression and increased matrix metalloproteinase-9 activity. Incomplete deposition of laminin and type IV collagen beneath the basal cells was observed only in the pressure-loaded 3DOMM. Cyclic pressure-loading appeared to disrupt multiple functions of the basal cells in the 3DOMM, resulting in a predisposition towards terminal differentiation. Thus, denture-wearing could compromise oral epithelial homeostasis.

Human papillomavirus genotype distribution in cervical intraepithelial neoplasia grade 2/3 and invasive cervical cancer in Japanese women

OBJECTIVE

Human papillomavirus vaccines are being introduced worldwide and are expected to reduce the incidence of cervical cancer. Here we report a cross-sectional study using a validated human papillomavirus genotyping method to reveal the human papillomavirus prevalence and genotype distribution in Japanese women with cervical intraepithelial neoplasia Grade 2/3 and invasive cervical cancer.

METHODS

Cervical exfoliated cells were collected from 647 patients with abnormal cervical histology (cervical intraepithelial neoplasia Grade 2, n = 164; cervical intraepithelial neoplasia Grade 3, n = 334; and invasive cervical cancer, n = 149), and subjected to the PGMY-PCR-based genotyping assay. The association between human papillomavirus infection and lesion severity was calculated using a prevalence ratio.

RESULTS

Overall, the prevalence of human papillomavirus deoxyribonucleic acid was 96.3% in cervical intraepithelial neoplasia Grade 2, 98.8% in cervical intraepithelial neoplasia Grade 3 and 88.0% in invasive cervical cancer (97.8% in squamous cell carcinoma and 71.4% in adenocarcinoma). The three most prevalent types were as follows: human papillomavirus 16 (29.3%), human papillomavirus 52 (27.4%) and human papillomavirus 58 (22.0%) in cervical intraepithelial neoplasia Grade 2; human papillomavirus 16 (44.9%), human papillomavirus 52 (26.0%) and human papillomavirus 58 (17.4%) in cervical intraepithelial neoplasia Grade 3; and human papillomavirus 16 (47.7%), human papillomavirus 18 (23.5%) and human papillomavirus 52 (8.7%) in invasive cervical cancer. The prevalence ratio of human papillomavirus 16 was significantly higher in cervical intraepithelial neoplasia Grade 3 compared with cervical intraepithelial neoplasia Grade 2 (prevalence ratio, 1.62; 95% confidence interval, 1.26-2.13) and in squamous cell carcinoma compared with cervical intraepithelial neoplasia Grade 3 (prevalence ratio, 1.55; 95% confidence interval, 1.25-1.87). Multiple infections decreased from cervical intraepithelial neoplasia Grade 2/3 (38.4/29.6%) to invasive cervical cancer (14.1%), whereas co-infections with human papillomavirus 16/52/58 were found in cervical intraepithelial neoplasia Grade 2/3.

CONCLUSIONS

The results of this study provide pre-vaccination era baseline data on human papillomavirus type distribution in Japanese women and serve as a reliable basis for monitoring the future impact of human papillomavirus vaccination in Japan.

Genotype distribution of human papillomaviruses in Japanese women with abnormal cervical cytology

We report the prevalence and genotype distribution of human papillomaviruses (HPVs) among Japanese women with abnormal cervical cytology using the PGMY-CHUV assay, one of PGMY-PCR-based lineblot assays that was validated and shown to be suitable for the detection of multiple HPV types in a specimen with minimum bias. Total DNA was extracted from cervical exfoliated cells collected from 326 outpatients with abnormal Pap smears. Overall, 307 specimens (94%) were HPV-positive, 30% of which contained multiple genotypes. The prevalence of HPV DNA was 83% (49/59 samples) in atypical squamous cells of undetermined significance (ASC-US); 91% (20/22 samples) in atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (ASC-H); 97% (130/134 samples) in low-grade squamous intraepithelial lesion (LSIL); and 99% (85/86 samples) in high-grade squamous intraepithelial lesion (HSIL). Three most frequent HPV types detected in HSIL were HPV16 (36%), HPV52 (24%), and HPV58 (14%). Our results suggest that multiple HPV infections are more prevalent in Japanese women than previously reported, and confirm that HPV52 and 58 are more dominant in their cervical precancerous lesions when compared to those reported in Western countries.

[A case of stage IVb vulvar cancer effectively treated by concurrent chemoradiotherapy with cisplatin]

A 72-year-old woman was hospitalized because of a 10 cm tumor in her right inguinal area. Furthermore, a 6 cm tumor mass was observed in her right vulva. Computed tomography revealed multiple swollen lymph nodes in the para-aortic and pelvic areas. On the basis of these findings, the patient was diagnosed with stage IVb squamous cell carcinoma of the vulva. Radiation therapy of 67.4 Gy/33 Fr was administered to the pelvis, inguinal area and vulva. Four courses of chemotherapy with cisplatin (40 mg/m(2)) were concurrently administered every week during radiation therapy. The response to chemoradiotherapy was assessed to be complete. The patient has been doing well without any recurrence for 24 months.

228 EXPRESSION OF zag1 IN MOUSE PRE-IMPLANTATION EMBRYOS

Embryonic gene activation (EGA) first occurs during the second half of the mouse 1-cell embryo (Latham KE 1999 Int. Rev. Cytol. 193, 71–124). Moreover, precise regulation of EGA is considered to be essential for normal embryo development. To understand the molecular basis for the regulation of EGA, we have focused on the identification and functional characterization of genes activated at the late 1-cell stage of the mouse embryo. Recently, we have identified and isolated a novel gene, termed zag1 (zygotic activating gene 1), transcribed specifically at the EGA, using a fluoro-differential display method with oocytes and embryos at 15 h post-insemination. Messenger RNA of zag1 expressed at lower level in the oocyte than that in the embryo at 15 h post-imsemination. In this study, we investigated the potential function of zag1 by analysis of mRNA expression and protein distribution in mouse tissues and pre-implantation embryos. Nucleotide sequence analysis of zag1 cDNA revealed that the open reading frame of 1726 bps encodes a protein of 575 amino acids with a predicted molecular mass of 66 kDa. The deduced amino acid sequence indicated that zag1 protein might be a soluble protein with a bipartite nuclear targeting sequence, a NACHT NTP domain, and an APT/GTP binding site motif as a predicted functional domain. Two μg of Poly(A)+ RNA from various tissues of adult mice were subjected to Northern blot analysis using the mouse zag1 cDNA probe. We detected this gene abundantly expressed in mouse testis and ovary by approximately 2- to 3-fold compared with one in other mouse tissues (heart, liver, kidney, lung, brain, skeletal muscle, and spleen). zag1 transcript and protein, as assessed by RT-PCR and immunoblotting, respectively, were slightly present in ovulated oocytes, gradually decreased in the early 1-cell embryos, but re-expressed in the late 1-cell and early 2-cell stage embryos which coincided with the mouse EGA. Subsequent to microinjection of an expression vector encoding zag1-enhanced green fluorescent protein (EGFP), fused protein into male pronucleus of 1-cell embryos was detected in the nuclei of 2-cell embryos. These findings suggest that zag1 may be functionally associated with early embryonic development. This study was supported by a Grant-in-Aid for the 21st Century COE Program of the Japan MEXT, and by a grant from the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence of the JST.

Muscle activities in the hand and arm during tooth brushing and the regulation of brushing movements by oral sensory perception

Investigations were made of the forces during brushing of the teeth, the patterns of brushing movements, and muscle activities, with and without blockage of sensory perception in the oral cavity, while each subject brushed by the rolling method, scrubbing method, and by his own individual habitual brushing method. We learned from electromyograms that the scrubbing method primarily used the muscles of the palm of the hand and the forearm, while the rolling method cleaned principally by action of the muscles of the upper arm and shoulder. With the rolling method, the rhythmic pattern of the brushing movement and muscle activity were lost when sensory perception in the oral cavity was blocked and, in those subjects who had a low periodontal membrane tactile threshold, the brushing force was greater than when sensory perception was not blocked. However, no effect was observed with blockage of the sensory perception in the oral cavity when the scrubbing method was used. Since brushing movements with the scrubbing method resemble the movements of writing, we also carried out investigations on the relationship between the forces during writing and brushing. As a result we found that with the scrubbing method, the brushing forces were strong for the subjects who had strong writing forces, while they were weak for those with weak writing forces. It was clear from the above results that the force of brushing with the rolling method was affected more by factors relating to oral sensory perception than muscle activity, while with the scrubbing method it was affected more by factors relating to muscle activity of the palm of the hand and forearm than by oral sensory perception. There was a clear difference in the brushing forces, pattern of brushing movements, and muscle activity between experienced and inexperienced subjects with both the scrubbing and rolling methods. Thus we learned that the effect of brushing instructions could be evaluated not only by the efficiency of plaque removal, brushing force or skill of brushing movements, but also by muscle activity. The phenomena observed with the scrubbing and rolling methods were not seen with the subjects' individual habitual brushing method.