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Biomedical subjects

Z P Ren

Publications and source records attributed to Z P Ren.

4 recordsLinked to original sources
PubMed1995

Ultraviolet light induces expression of p53 and p21 in human skin: effect of sunscreen and constitutive p21 expression in skin appendages.

It has been suggested that p53 plays an important role in skin carcinogenesis. The p21 molecule acts as a downstream effector of wild-type p53 by enacting cell cycle arrest. We studied p53 and p21 expression in sun-exposed skin. Healthy volunteers were exposed to ultraviolet irradiation (UVA + UVB) in normal, previously non-sun-exposed skin, and skin biopsies were taken. Immunohistochemically detectable p53 and p21 were quantified, and the pattern of distribution was recorded. p53 was induced in epidermal cells 4 h after irradiation and returned to nearly normal levels after 120 h. Suprabasal cells showed a peak at 4 h, whereas basal cells peaked later, at 48 h. In epidermis, the expression of p21 was induced with a pattern that mirrored that of p53. In addition, p21 was induced in mesenchymal cells of the upper dermis, where there was no p53, suggesting an alternative pathway for p21 induction. Topical sunscreen and pigmentation (skin type 5) nearly eliminated UV-induced expression of p53 and p21. In contrast to the complete absence of p53 in skin never exposed to UV radiation, p21 reactivity was found in sharply demarcated areas of anagen hair follicles and sebaceous glands, as well as in scattered epidermal cells. The prevalence and distribution suggest a physiologic role of p21 in stopping the cell cycle in terminally differentiating skin epithelium. Archival skin material from the vicinity of skin lesions with variable sun exposure were also stained for p53. There was an increased "disperse" reactive staining pattern in skin samples excised in the summer as compared with less sunny seasons. Intensely stained p53 foci were detected as "compact bands" in morphologically normal epidermis, predominantly in sun-exposed areas of the skin, suggesting the existence of clonal proliferation of p53 mutated keratinocytes. These data show that p53 and p21 play a role in the human skin response to UV exposure and that p21 is implicated in the homeostasis of differentiating skin appendages.

Adult↗
PubMed1995

Ischemia-induced transplant arteriosclerosis in the rat.

The effect of cold graft ischemia time on the development of transplant arteriosclerosis was investigated. Aorta grafts from DA or PVG rats were stored in a cold perfusion solution for 1, 4, or 24 hours before being orthotopically transplanted to PVG recipients. After observation times ranging from 2 to 8 weeks, the grafts were examined for various cell populations. Regional changes in the intima and media layers were measured by using an image analysis system. The arteriosclerosis-like changes seen in syngeneic grafts with the longest ischemia time could be almost as prominent as those seen in the allogeneic transplants. The magnitude of the regional intima changes in the syngeneic group correlated well with the ischemia time and in the allogeneic group with the observation time. The cell composition found in the intima and media of the allogeneic vessels consisted of macrophages, T-lymphocytes, MHC class II-expressing cells, and smooth muscle cells, whereas the syngeneic grafts contained almost exclusively smooth muscle cells and macrophages. We therefore conclude that the damage due to prolonged cold ischemia time is sufficient to cause pronounced graft arteriosclerosis. The pathophysiological mechanism leading to ischemia-induced arteriosclerosis is different from the one seen in the allogeneic situation.

Animals↗
PubMed1993

Constitutive and inducible expression of PDGF in the human basophilic cell line, KU 812.

The human basophilic cell line KU 812, that also has some mast cell characteristics, was found to express the PDGF-A gene and secrete PDGF-A like activity. After treatment with IL-6+ TNF-alpha, the PDGF-A mRNA expression increased as did cytoplasmic immunostaining with anti-PDGF antibodies. Secretion of PDGF-A was visualized by immunoprecipitation. An augmentation of non-secreted PDGF-like activity after IL-6+ TNF-alpha treatment was not accompanied by induction of the long splice variant of the PDGF-A-chain mRNA. Treatment with TPA caused an increase in PDGF-A expression and in addition, an induction of PDGF-B transcripts were seen. Staining of cytospin preparations with anti-PDGF antibodies visualized a substantial increase in immunostaining of the TPA treated cells and both intracellular and secreted PDGF-AA-like activity was substantially increased as compared to untreated control cultures. There was a concomitant induction of exon 6 specific mRNA, corresponding to a cellular retention signal after TPA treatment. Our results show that PDGF can be produced by a cell line of the basophilic/mast cell lineage, i.e. cells involved in allergic disorders and inflammation.

Basophils↗