Ovariectomy is sufficient to accelerate spontaneous skin ageing and to stimulate ultraviolet irradiation-induced photoageing of murine skin.

BACKGROUND: Wrinkling and sagging of the skin during photoageing is physiologically associated with diminished elasticity, which can be attributed to increased fibroblast-derived elastase activity. This degrades the dermal elastic fibres needed to maintain the three-dimensional structure of the skin. We previously reported that ovariectomy accelerates ultraviolet (UV)B-induced wrinkle formation in rat hind limb skin by altering the three-dimensional structure of elastic fibres. OBJECTIVES: In this study, we used hairless mice to assess the effects of ovariectomy with or without chronic UVA or UVB radiation on sagging and wrinkling of skin, on the elasticity of skin, as well as on matrix metalloproteinase activities in the skin. METHODS: Ovariectomies or sham operations were performed on 6-week-old female ICR/HR hairless mice. RESULTS: Even in the ovariectomy group without UV irradiation, the skin elasticity was significantly decreased during the 3-13 weeks after ovariectomy, which was accompanied by a significant increase in elastase activity in the skin. After UVA or UVB irradiation, skin elasticity was significantly decreased to a greater extent in the ovariectomy group than in the sham operation group, and this was accompanied by a reciprocal increase in elastase activity but not in the activities of collagenases I or IV in the skin. Consistent with the decreased skin elasticity, UVA irradiation for 12 weeks elicited more marked sagging in the ovariectomy group than in the sham operation group. UVB irradiation for 12 weeks also induced more marked wrinkle formation in the ovariectomy group than in the sham operation group. CONCLUSIONS: These results suggest that ovariectomy alone is sufficient to accelerate skin ageing and to increase UV sensitivity, which results in the further deterioration of the skin and photoageing, and may account for the accelerated skin ageing seen in postmenopausal women.

Establishment of human cementifying fibroma cell lines by transfection with temperature-sensitive simian virus-40 T-antigen gene and hTERT gene.

Human cementifying fibroma (HCF) is a benign fibro-osseous neoplasm of periodontal ligament (PDL) origin containing varying amounts of mineralized material resembling cementum. In the present study, we established cell lines from HCF, which were detected in the mandible of a 54-year-old Japanese man. To obtain immortalized cell clones, we undertook transfection with temperature-sensitive simian virus-40 (SV40) T-antigen and hTERT into HCF cells. Cells transfected with SV40 T-antigen entered "crisis" state between passages 22 and 35, but activation of telomerase by transfection with hTERT in the SV40-transformed HCF cells resulted in bypass of the crisis and maintenance over passage 200. HCF cell lines decreased the expression of SV40 T-antigen and the activity of cell proliferation at a nonpermissive temperature (39 degrees C) in comparison with that at a permissive temperature (33 degrees C). High activities of alkaline phosphatase and mineralization and the expression of type I collagen, osteocalcin, osteopontin, and bone sialoprotein by reverse transcription-polymerase chain reaction (RT-PCR) were observed in HCF cells at 39 degrees C. Overall, these findings suggest that: (i) HCF cell lines may represent a novel in vitro human cell model for the study of the regulatory mechanism of differentiation and proliferation of the human PDL; and (ii) transfection of plasmids encoding the temperature-sensitive SV40 T-antigen gene and hTERT gene may be useful for obtaining immortalized cell lines from benign human tumor and, probably, nonneoplastic human tissues.

Human is a unique species among primates in terms of telomere length.

TRF (terminal restriction fragments) length in various tissues of non-human primates such as Macaca mulatta (rhesus monkey), Macaca fuscata (Japanese monkey), Macaca fascicularis (crab-eating monkey), Pan troglodytes (common chimpanzee), and Pongo pygmaeus (orangutan) was at least 23 kb without exception, which was quite different from that of human somatic tissues (smaller than 10 kb). The distribution pattern of telomerase activity among tissues was similar between human and non-human primates, while the activity level showed some differences such as that strong telomerase activity was observed in gastrointestinal and lymphocytic tissues from non-human primates. The human appears to be a unique species among primates in terms of telomere length.