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Biomedical subjects

F Urbach

Publications and source records attributed to F Urbach.

At least 19 recordsLinked to original sources
PubMed1991

Evaluation of halobetasol propionate ointment in the treatment of plaque psoriasis: report on two double-blind, vehicle-controlled studies.

The results of two studies are presented that reveal the efficacy and safety of 0.05% halobetasol ointment in the treatment of patients with plaque psoriasis of at least moderate severity. Both multicenter studies were randomized, double-blind, and vehicle controlled, and study medications were applied twice daily for 2 weeks. One study was a paired-comparison (PC); the other study was of parallel-group (PG) design. Both studies called for evaluations at entry (week 0) and after 1 and 2 weeks of treatment. The PC study enrolled 100 patients; the PG study enrolled 110 patients; 204 patients provided efficacy data over both studies. In the PC study, plaque elevation, erythema, and scaling, at least moderately severe at entry, showed at the end of treatment both statistical (p less than or equal to 0.0003) and clinical significance (all greater than 1-unit difference on the rating scale) favoring 0.05% halobetasol ointment over vehicle. Pruritus (initially mild) and total score also showed statistically significant treatment differences favoring halobetasol at the final evaluation. Patient global responses for "effectiveness" and "overall rating" favored 0.05% halobetasol ointment over vehicle. In the PG study, induration, erythema, and scaling, at least moderately severe at entry, showed at the end of treatment both statistically and clinically significant differences favoring 0.05% halobetasol ointment over vehicle. Physician's global evaluation favored 0.05% halobetasol ointment over vehicle after 2 weeks of use. No patients were released from either study because of adverse events. No systemic adverse events or findings of skin atrophy were reported in these studies. Reports of "stings" or "burns" were equally divided between halobetasol and its vehicle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Potential health effects of climatic change: effects of increased ultraviolet radiation on man.

There is scientific evidence that stratospheric ozone concentration has declined over the Northern Hemisphere in the past 20 years, and projections based on various assumptions about future release of chlorofluorocarbon gases and other contaminants suggest that this decline will continue into the next century. The effects on human health secondary to increase in biologically effective ultraviolet radiation are expected to consist of increases in nonmelanoma skin cancer and malignant melanoma of the skin, possible alteration of immune response, and development of lens cataracts. The recent and projected increases in skin cancer and changes in human immune responses are discussed.

Adaptation, Physiological↗
PubMed1991

Incidence of nonmelanoma skin cancer.

Nonmelanoma skin cancers are the most common malignant neoplasms of fair-skinned people, in many sunny countries exceeding the total of all other neoplasms. The evidence that the primary causal agent is chronic repeated exposure to solar ultraviolet radiation is overwhelming. The incidence of basal cell carcinoma is always greater than that of squamous cell carcinoma, varying by latitude from 10:1 to 2.5:1. The incidence of nonmelanoma skin cancer has been increasing by 2% to 3% per year, at least in the United States. Most likely, this is caused by greater outdoor exposure for leisure and social reasons.

Africa↗
PubMed1979

Bowen's disease and squamous cell carcinoma. Occurrence in a patient with psoriasis after topical, systemic, and PUVA therapy.

Multiple lesions of Bowen's disease and squamous cell carcinoma on the penis and pubic areas developed in a 32-year-old patient with psoriasis who was undergoing treatment with psoralen and long-wave ultraviolet radiation (PUVA). A cumulative dose of more than 3,700 joules/sq cm of UVA had been administered over a three-year period. This case may be an early warning of possible carcinogenicity of PUVA therapy, alone or as part of sequential therapy with other agents.

Adult↗
PubMed1979

Enhancement of experimental photocarcinogenesis by topical retinoic acid.

Topical application of retinoic acid (RA) solutions greatly enhanced the response of hairless mouse skin to a moderate dose of simulated sunlight. Tumors appeared much earlier, and in much greater numbers, in animals treated daily with 1 or 10 micrograms of RA in methanol immediately after 2 h exposure to a xenon arc filtered through 2 mm of Schott WG 320 glass (approximately equivalent in human erythema effectiveness to 5 min of mid-summer noon solar exposure in northern mid-latitudes), compared to mice treated with light and methanol only. The higher amount of RA, in combination with light, produced moderate epidermal hyperplasia and some scaling and transient erythema, but no gross ulceration or inflammation of skin. The lower amount of RA, though about equally effective in carcinogenesis, produced minimal epidermal hyperplasia compared to the ultraviolet radiation + methanol control.

Administration, Topical↗
PubMed1979

Normal T-lymphocyte function in psoriatic patients undergoing methoxsalen photochemotherapy.

Peripheral blood lymphocytes from psoriatic patients undergoing photochemotherapy using oral 8-methoxypsoralen and high-intensity long-wave ultraviolet radiation, were isolated and their ability to respond to phytohemagglutinin and to form spontaneous rosettes with sheep red blood cells was measured in vitro. Seventeen patients were investigated who had received 200 to 3700 Joules/cm2 of ultraviolet radiation over a 6- to 33-month period. No significant defects in lymphocyte blastogenesis or E-rosette formation were detected in these patients.

Adult↗
PubMed1979

Aging, environmental influences, and photocarcinogenesis.

Repeated exposure of human skin to solar ultraviolet radiation (UVR) over a period of many years is responsible for the induction of most nonmelanoma skin cancers in man. The tumors are progressively more common in chronologically older people. Is this fact purely a function of adequate dose accumulation and development time, or is tumor expression influenced by "physiological age"? The answer to this question influences risk estimates of the results of atmosphere modification. Data from animal studies indicate that the tumor incidence is affected by dose-delivery factors and not just by the accumulated lifetime dose. In addition, young mice are more prone to tumor induction by a given UVR dose than are older animals. Because the quanlity and quantity of the stimulus (UVR) can be readily manipulated and accurately described, studies on photocarcinogenesis offer distinct possibilities for untangling some of the interactive variables in the aging process.

Aged↗
PubMed1978

Mycosis fungoides, nitrogen mustard and skin cancer.

The prevalence of epithelial cancer was determined in 202 patients with mycosis fungoides and the Sézary syndrome and was found to be 10.5%. In an attempt to establish a possible association with topically applied nitrogen mustard, it was noted that 4.0% of these patients had lesions prior to nitrogen mustard therapy (although over half subsequently developed further lesions) and 6.5% of the patients developed them de novo after therapy. In two patients in this latter group, malignancies developed in are as not usually associated with solar-induced cancer. These findings indicate that epidermal neoplasia is not uncommon in these patients and that nitrogen mustard may function as a carcinogen or a co-carcinogen.

Administration, Topical↗
PubMed1978

The correlation of indoor solar simulator and natural sunlight: testing of a sunscreen preparation.

To determine the equivalence of xenon arc solar simulator and natural sunlight test results, the sun protection factor (SPF) for an experimental sunscreen preparation was determined using each light source. The minimal erythemal doses (MEDs) were shown to be equivalent on unprotected skin. It was necessary to supply additional heat to the treated skin prior to solar simulator exposures to obtain comparable SPFs. By careful control of the subjects' environment, natural sunlight effects can be duplicated with a solar simulator.

Dermatology↗
PubMed1978

Recommendations for future research on ultraviolet radiation carcinogenesis.

Recommendations for future research on photocarcinogenesis were developed during an international conference on UVR carcinogenesis. Areas covered in the recommendations include research at the molecular biology level, human (especially epidemiologic aspects), physical (including instrumentation), and biologic studies (stressing animal models). The recommendations also propose the establishment of central supply and service sources for photocarcinogenesis research as well as the establishment of interdiscipilinary training programs related to research in photocarcinogenesis.

Animals↗
PubMed1978

Experimental ultraviolet photocarcinogenesis: wavelength interactions and time-dose relationships.

Tumors were induced in the skin of SKH hairless mice by exposure to fluorescent FS sun lamps or to a long-arc xenon solar simulator. Tumores developed about equally well with varying amounts of UV-A radiation (lambda greater than 320 nm) given simultaneously. In contrast, incremental changes in the UV-B region (lambda less than 320 nm) led to substantial increases in carcinogenic effectiveness. A tumor-"initiating" dose of UV-B (4-10 wk of daily FS lamp exposures) was rendered less effective by subsequent exposures of the mice to UV-A (6 hr/day, F-40 T12BL lamps). The mechanism for this effect is not known. Most tumors induced by a short course (10 wk) of FS lamp exposure grew slowly or regressed, whereas mice exposed for a longer period (30 wk) developed more tumors, and many of those that appeared early grew aggressively. Effects of daily dose fractionation were less clear, and the subject requires further study. These and other variables are being tested in a program designed to yield useful information on the effects of changing spectrum, dose, and dose delivery rates on sunlight-induced cancer.

Animals↗
PubMed1976

Modification of photocarcinogenesis by two immunosuppressive agents.

The carcinogenic effect of ultraviolet radiation (UVR) on the skin of hairless (hr) mice was modified by two immunosuppressive agents, rabbit anti-mouse lymphocytic serum (ALS), and 6-mercaptopurine (6MP). Daily exposure of mice to UVR resulted in multiple tumor production. Carcinogenesis was measured in terms of affected mice (prevalence) and numbers of tumors produced. By both criteria, photocarcinogenesis was enhanced by ALS but inhibited by 6MP.

Animals↗
PubMed1976

Cutaneous photobiology: past, present and future.

The history and origin of the science of photobiology are reviewed. Interest in the biologic effects of light gradually increased, beginning with the discovery of ultraviolet and infrared radiation early in the 19th century. The basis of experimental photobiology was laid by the studies of Raab and Tappeiner on photodynamic action and the early uses of phototherapy by Finsen and Dorno. The discovery of the association of porphyrins with some light-related skin diseases and of the capability of chemical agents such as coal tar and bergamot to induce phototoxic contact dermatitis resulted in a flurry of clinical investigations leading to better understanding of the processes of phototoxicity and photoallergy. The early epidemiologic studies of Unna and Dubreuilh relating solar radiation exposure to the formation of actinic keratoses and non-melanoma skin cancer were experimentally confirmed in animals by Findlay, Roffo, and Blum. In the most recent quarter century (1950-1975), cellular and molecular photobiology has been refined. The studies on photochemistry of nucleic acid and of damage and repair mechanisms in DNA have set the stage for understanding the basic processes of biologic effects of light and promise the development of useful applications of specifically directed phototherapy and prevention of such light-induced diseases as skin cancer.

Animals↗