Comparison of histological measures of skin photoaging.

BACKGROUND: Dermal elastosis is considered the histological 'gold standard' for evaluation of skin photoaging, but the relation of the level of dermal elastosis to other histological indicators of photoaging is not clear. OBJECTIVE: To investigate how various proposed histological measures of photoaging compare with the level of dermal elastosis. METHODS: Prospective, community-based study in Southeast Queensland, Australia, among 89 participants aged 40-82 years. Quantitative histology was used to evaluate 8 biomarkers of photoaged skin, and associations between grades of dermal elastosis and each of the other 7 biomarkers were analysed using ordinal logistic regression models with proportional odds assumption, using histological grades of elastosis as the outcome. RESULTS: Older age, male sex and high outdoor exposure levels were confirmed as predictors of high levels of dermal elastosis. After adjustment for age and sex, the only significant positive association with increasing elastosis grades was the proportion of p53-positive cells. Epidermal thickness, interdigitation index proportion of surface covered with melanin (% Fontana-Masson staining) and glycosaminoglycan content were not associated with elastosis in either crude or adjusted models. CONCLUSIONS: Among a range of suggested biomarkers of photoaged skin, only p53-positive cells appear to be strongly associated with the level of dermal elastosis.

A broad-spectrum sunscreen prevents cumulative damage from repeated exposure to sub-erythemal solar ultraviolet radiation representative of temperate latitudes.

BACKGROUND: We have previously shown the detrimental effects of 19 sub-erythemal exposures to daily ultraviolet radiation (DUVR, which mimics non-extreme exposure conditions), delivered over 4 weeks to volunteers. This source had UVA (320-400 nm) to UVB (290-320 nm) irradiance ratio of 25, instead of that close to 10 that is typically the case with solar-simulated radiation (SSR) that represents summer global sunlight with a clear sky and quasi-zenith solar irradiance. OBJECTIVE: Here, we report on an extension of this previous study, in which we evaluated the photoprotection afforded by a broad-spectrum daily-care product with a low-sun protection factor (SPF 8, UVA-PF 7 and 3* rated UVA protection). We assessed cellular and molecular markers of photodamage that are relevant to skin cancer and photoageing. RESULTS: This study shows that biological effects of repeated exposure to DUVR can be prevented by a broad-spectrum daily-care product and that the level of protection afforded varies with the studied endpoint. CONCLUSION: Efficient daily UVR protection, as provided by a broad-spectrum daily-care product, is necessary to prevent the 'silent' sub-erythemal cumulative effects of UVR from inadvertent sun exposure.

Expression of tie receptor tyrosine kinase in human leukemia cell lines.

The tie gene encodes a receptor tyrosine kinase that together with its thus far unidentified ligand appears to play a distinct role in the regulatory pathway of early hematopoiesis and angiogenesis. Here, we attempted to define the possible involvement of tie in the pathobiology of hematopoietic malignancies by examining tie mRNA expression in human leukemia and lymphoma cells. We used a large panel of 93 well-characterized human continuous leukemia-lymphoma cell lines as model systems for the various hematopoietic cell lineages. At the Northern blot level, none of the 27 lymphoid leukemia or lymphoma-derived cell lines (originating from four B-precursor leukemia, four B-cell leukemia, four B-cell non-Hodgkin's lymphoma, two myeloma, two Burkitt lymphoma, four T-cell leukemia, five Hodgkin lymphoma, two anaplastic large cell lymphoma) tested expressed tie transcripts, whereas 23/42 (55%) of the myeloid cell lines analyzed expressed tie mRNA: in detail, 15 of 20 (75%) megakaryocytic, five of 11 (45%) erythroid, three of seven (43%) myelocytic and none of four monocytic cell lines were tie mRNA positive. In the reverse transcriptase-polymerase chain reaction analysis, which can detect very low levels of mRNA expression, all 12 myeloid cell lines and 19 of 39 (48%) lymphoid cell lines were positive. In experiments aimed at inducing cellular differentiation over an incubation period of 4 days, the phorbol ester PMA strongly enhanced tie mRNA expression in one erythroid and in one myelocytic cell line, but (like thrombopoietin) down-regulated tie mRNA expression in two megakaryocytic cell lines. Taken together these results indicate that tie is predominantly expressed in leukemia cells derived from the myeloid cell lineages (and here in particular in megakaryoblastic cells) and not in lymphoid leukemia cells. These observations provide some evidence for the hypothesis that tie is a receptor for a regulatory factor involved in normal and plausibly also leukemic hematopoiesis.

Histological evaluation of a topically applied retinol-vitamin C combination.

Two double-blind studies versus vehicle were carried out to investigate the effects of a topically applied retinol plus vitamin C combination on epidermal and dermal compartments of aged or photoaged human skin. The two studies were performed on postmenopausal women who were selected for treatment based on the mild level of elastosis of their facial skin. At completion of treatment, skin biopsies were collected and processed for classical histology and immunohistochemistry. In the first study (aged skin), 8 volunteers applied the retinol- and vitamin C-containing preparation on the ventral side of one elbow and the vehicle on the other elbow twice daily for 3 months. After the 3-month treatment we observed histological changes mainly within the epidermis. The stratum corneum was thinner with a compact pattern, whereas the epidermal proliferation increased, resulting in a thickening of the viable epidermis. Moreover, the interdigitation index was increased. In the second study (photoaged skin), 11 volunteers were divided in two groups; one applied the retinol- and vitamin C-containing preparation and the other one the vehicle on their face twice daily for 6 months. Facial skin samples presented histologic hallmarks of photoaging, i.e. accumulation of elastotic material in the papillary dermis. After the 6-month topical treatment, the observed histological changes were mainly concentrated at the dermal level. Both treated and control groups showed the same distribution pattern of type I procollagen, however, the high level of type III procollagen originally observed in photoaged skin was reduced in the retinol- and vitamin C-treated group, resulting in a lower type III-to-type I procollagen ratio. Furthermore, a wide band of eosinophilic material just beneath the epidermis, devoid of oxytalan fibers and forming the 'grenz zone', appeared more frequently and was larger in the retinol- and vitamin C-treated group. In conclusion, our results show that repeated topical application of a preparation containing both retinol and vitamin C is able to reverse, at least in part, skin changes induced by both chronologic aging and photoaging.