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Biomedical subjects

B A Gilchrest

Publications and source records attributed to B A Gilchrest.

195 records · Page 11Linked to original sources
PubMed1980

Prior chronic sun exposure decreases the lifespan of human skin fibroblasts in vitro.

The relationship of actinically-induced "premature aging" to chronologic aging was studied in paired fibroblast cultures obtained from the habitually sun-exposed (lateral) and nonexposed (medial) aspects of the arm of eight male donors, aged 41 to 80 years. In each case, the fibroblast strain derived from the medial, nonexposed aspect of the arm underwent more cumulative population doublings than did the paired strain from the lateral sun-exposed aspect, and this discrepancy increased with donor age and severity of clinical aging changes. Hence, chronic sun exposure does accelerate aging in human skin by at least one established in vitro criterion: it decreases the lifespan of cultured fibroblasts. The data underline the difficulty of distinguishing environmental effects from intrinsic aging changes.

Adult↗
PubMed1979

Relationship between actinic damage and chronologic aging in keratinocyte cultures of human skin.

The relationship of actinically-induced "premature aging" to chronological aging was studied in paired keratinocyte cultures obtained from the habitually sun-exposed (lateral) and nonexposed (medial) aspects of the arm of 5 male donors, aged 41 to 80 yr. In all cases, the number of cell generations in vitro was greater for cultures derived from sun-exposed skin, and this discrepancy increased with donor age and the severity of clinical aging changes. Hence, chronic sun exposure does accelerate aging in human skin by at least one previously established in vitro criterion: it decreased the lifespan of cultured keratinocytes. Plating efficiency was 11- to 32-fold higher for keratinocytes from chronically sun-exposed skin than nonexposed controls, perhaps reflecting the recognized carcinogenic potential of actinic radiation. Keratinocyte cultures appear to be as amenable to gerontologic studies as the already widely used human fibroblast cultures.

Adult↗
PubMed1979

Effects of aging and chronic sun exposure on melanocytes in human skin.

Both aging and sun exposure have well-documented effects on the human melanocyte system. Paired biopsies of habitually exposed and nonexposed skin from adjacent anatomic sites were obtained from 8 donors aged 28 to 80 yr in order to study the combined effect of chronic actinic irradiation and chronologic aging. Density of dopa-positive melanocytes was roughly twofold higher in the exposed than in the nonexposed skin at all ages, suggesting an irreversible effect of sun exposure. Melanocyte density declined approximately 6 to 8% of the surviving population per decade in both sites. Dopa-positivity of individual melanocytes was consistently greater in the chronically exposed skin than in the nonexposed skin of the same subject and did not vary with age. These data strengthen and expand earlier observations of age-related melanocyte changes, and explain the apparent paradox of a generalized increase in pigmentation and simultaneous decrease in melanocyte density which frequently accompany advancing age. In addition, the present study suggests that the principal effect of chronic sun exposure on the human pigmentary system is not premature "aging" as currently recognized histologically, but rather activation and/or proliferation of the exposed melanocytes.

Adult↗
PubMed1979

Ultraviolet phototherapy of uremic pruritus.

Repeated exposure to mid-range ultraviolet light (UVB) can dramatically relieve the pruritus associated with uremia. The efficacy of UVB phototherapy in uremic pruritus has been established in a controlled trial; experience with 38 patients suggests that 80 to 90% of those receiving 6 to 8 exposures respond favorably within the treatment period (2 to 5 weeks). Treatment frequency appears not to influence the remission rate, although patients on more intensive schedules experience relief sooner than those treated once weekly. Remissions are long-lasting in many patients, sometimes longer than 2 years. Patients with recurrent pruritus respond to phototherapy at least as well as previously untreated patients and tend to improve more rapidly. UVB phototherapy appears to exert its beneficial effect systemically rather than locally, but its mechanism of action is otherwise unknown.

Adult↗
PubMed1979

Ultraviolet phototherapy of uremic pruritus. Long-term results and possible mechanism of action.

The beneficial effect of sunburn-spectrum ultraviolet (UVB) phototherapy on uremic pruritus was studied. Seven patients were treated twice weekly for 4 weeks with UVB to one half of the body and placebo phototherapy to the other half. All patients noted generalized improvement without localization of benefit to the UVB side, suggesting a systemic effect of UVB. A comparison of three schedules varying from one to three treatments weekly showed that the percentage of patients responding was not influenced by frequency of UVB exposure, although patients treated more intensively improved faster. In three patients, improvement was delayed until 2 weeks after completion of a course of six treatments over 2 weeks, indicating a delayed onset of benefit in at least some patients. Overall 32 of 38 patients improved after a course of six or eight UVB exposures. Pruritus has recurred in 15 patients after a mean remission of 3 months. Sixteen patients are known to remain in remission for a mean of at least 10.6 months after the first or second course of treatment. The present evidence indicates a systemic mechanism of action for the long-lasting relief of uremic pruritus afforded by UVB phototherapy.

Adult↗
PubMed1979

Methoxsalen photochemotherapy for mycosis fungoides.

Methoxsalen photochemotherapy (PUVA; psoralen plus ultraviolet light) is effective in the treatment of mycosis fungoides (MF). The mechanism of this beneficial effect is unknown but probably involves covalent photo-binding of methoxsalen molecules to pyrimidine bases in DNA at the cellular level and impaired T-cell function or survival at the tissue level. Eleven patients (seven with plaques and four with erythroderma) were referred for PUVA therapy because of poor response to conventional therapy. Seven patients had complete clearing of skin lesions and three improved markedly. All ten of these patients experienced good to excellent control of the disease while receiving maintenance therapy, resulting in a virtual remission lasting for greater than 2 years in four patients. Of the six patients who discontinued PUVA during the followup period, three died within 1 year and three experienced progression of MF despite conventional therapy. The very promising results in this small patient group should encourage further studies of PUVA for cutaneous T-cell lymphomas.

Aged↗
PubMed1979

Some gerontologic considerations in the practice of dermatology.

Gerontology and geriatrics are areas of increasing importance in medicine today. Although changes in the appearance and behavior of human skin have long been noted to accompany aging, physicians have only recently begun to consider the impact of such an age-associated change on the manifestations of dermatologic disease and on the dermatologic management of elderly patients. Gerontologic studies in such fields as immunology, epidermal cell kinetics, DNA damage and repair, and therapeutics are potentially of great relevance to the practicing dermatologist and deserve increased emphasis within our specialty.

Age Factors↗
PubMed1977

Relief of uremic pruritus with ultraviolet phototherapy.

We studied the effect of ultraviolet-light phototherapy on severe persistent pruritus in 18 adult patients on hemodialysis. Patients were randomly assigned to one of two light sources. The experimental group received conventional sunburn-spectrum light in gradually increasing doses. The control group received time-matched exposures to long-wave ultraviolet light. All patients received eight exposures to the entire skin surface over a four-week treatment period. Nine of 10 patients in the sunburn-spectrum group reported marked decrease in pruritus as opposed to two of eight in the placebo group (P less than 0.01). of those responding to sunburn-spectrum light, improvement usually occurred two to three weeks into treatment. Mild sunburn, noted by some patients in this group, was the only side effect. The response to phototherapy was unaffected by the presence of secondary hyperparathyroidism. Ultraviolet phototherapy is a safe, convenient, inexpensive and effective treatment for uremic pruritus.

Adult↗
PubMed1977

Localization of malanin pigmentation in the skin with Wood's lamp.

Examination of the skin or hair with Wood's lamp has long been used to aid in the clinical diagnosis of some cutaneous disorders. A new observation reported here illustrates that Wood's light can be used to determine the depth of melanin pigmentation in the skin: contrast in epidermal pigmentation is increased while contrast in dermal pigmentation is decreased under Wood's lamp illumination compared to ambient visible light. The principles underlying this phenomenon are discussed. Use of the Wood's lamp to localize abnormal melanin pigmentation in the skin can be a guide to clinical diagnosis of hypermelanosis.

Diagnosis, Differential↗
PubMed1976

Oral methoxsalen photochemotherapy of mycosis fungoides.

The cutaneous manifestations of mycosis fungoides have been successfully treated in nine patients for 16 to 28 months with oral methoxsalen and subsequent irradiation with longwave ultraviolet light. The efficacy of this therapy was confirmed in one patient, who showed complete clearing of generalized plaques after 1 month (12 treatments) except for a shielded control area which worsened during this period. Methoxsalen photochemotherapy may prove a valuable addition to therapies currently available for mycosis fungoides and may obviate some of the problems associated with conventional management of this disorder.

Administration, Oral↗