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Biomedical subjects

R Marks

Publications and source records attributed to R Marks.

607 records · Page 34Linked to original sources

Non-melanotic skin cancer and solar keratoses in Victoria.

The light-exposed areas of the head and neck, forearms, and dorsum of each hand were examined in 2113 adults during a one-week study. The study was conducted in the isolated Victorian rural city of Maryborough which is situated in the northern part of the Central Highlands district. Of 2113 subjects, 49 (2.32%) had at least one skin cancer and 1202 (56.9%) had at least one solar keratosis. Histological confirmation of all skin cancers and doubtful solar keratoses was obtained. Age, skin type, and sunlight exposure were the major factors influencing the prevalence of solar keratoses and skin cancers.

Adult↗

Photoprotection and prevention of melanoma.

This article summarizes the current position on primary prevention of melanoma, including what is the evidence relating sunlight exposure to the development of melanoma, what forms of photoprotection there are and what are their relative values. There have been increasing incidence and mortality rates due to melanoma in most countries where they are being recorded. The initial approach in many countries has been to develop some form of early detection program in an attempt to diagnose and treat at a curable stage the melanomas that are occurring now. Primary prevention of melanoma is the more long term approach to the problem which many countries are now considering and a number are actively pursuing. Recent concern about stratospheric ozone depletion has contributed to the desire for the primary prevention approach. There are epidemiological data associating the risk of melanoma with increased exposure to sunlight in people with fair skin. They show that it is sunlight exposure in childhood and in doses sufficient to cause sunburn remembered many years later, that is particularly associated with risk of melanoma in adulthood. The exact spectrum of radiation in sunlight which is responsible for these tumours is not known, although the ultraviolet range is believed to be most important, particularly UVB but probably also UVA. The approach to photoprotection is a reduction in the overall exposure to sunlight, not just a single component of it. The natural protection of shade, clothing and hats is promoted as the best protection. Sunscreens have assumed a major component of primary prevention programs based on their convenience of use and also on their widespread promotion by those people who have a commercial interest in them. These products protect predominantly in the UVB range for which there is a sun protection factor (SPF) grading, as well as having some activity in the UVA range (for which there is not yet a satisfactory grading method).

Humans↗

The proteolytic activity of strains of T. mentagrophytes and T. rubrum isolated from tinea pedis and tinea unguium infections.

To understand the significance of proteolytic enzymes in the pathogenesis of dermatophyte infections, we have studied the expression of proteolytic activity in vitro. Cultures were extracted after 1, 2, 3, 4 and 5 weeks of growth and the proteolytic activity measured by a peptide release assay using human stratum corneum as a substrate. Maximum activity was noted at 3 weeks which corresponded to the dissolution of the stratum corneum particles. Isolates of Trichophyton mentagrophytes and Trichophyton rubrum from 42 patients with tinea pedis or tinea unguium were established on 2% glucose peptone plates. Using the peptide release assay it was found that after 3 weeks culture, T. mentagrophytes showed higher activity that T. rubrum in tinea pedis (2044 +/- 1067 micrograms protein released h-1 mg-1, n = 13 compared to 828 +/- 614 micrograms protein released h-1 mg-1, n = 13). In tinea unguium, the values at 3 weeks were generally lower. Trichophyton mentagrophytes activity was 837 +/- 121 micrograms protein released h-1 mg-1 (n = 3) compared to 470 +/- 271 micrograms protein released h-1 mg-1 (n = 13) for T. rubrum. Thus, as well as a variation in activity between the two species, there appears to be a variation in site in terms of expression of activity.

Female↗

Comparison between the surface electromyogram of the quadriceps surrounding the knees of healthy women and the knees of women with osteoarthrosis.

The purpose of this study was to compare the electromyographic (EMG) activity of the quadriceps femoris (QF) muscles of women with osteoarthrosis (OA) of the knee with the EMG activity of the QF muscles of healthy women. To this end, a total of 14 subjects attended a single test session during which full-wave rectified surface electromyograms were recorded from the rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) muscles during maximum voluntary isometric quadriceps contractions performed at knee angles of 30 degrees and 60 degrees flexion. A comparison of the resultant normalized peak EMG ratios using independent t-tests demonstrated significantly higher composite QF muscle activation for the osteoarthrotic subjects (p < 0.05). A higher RF activation also differentiated the two groups. The findings raise the possibility of a direct correlation between abnormal activation of the QF and joint status. They also suggest that patients with knee OA may benefit functionally from rehabilitation designed to improve QF coordination and endurance, and not merely strength.

Adult↗