Biomedical subjects

K Kaidbey

Publications and source records attributed to K Kaidbey.

13 recordsLinked to original sources

PubMed2004

Histological effects of tazarotene 0.1% cream vs. vehicle on photodamaged skin: a 6-month, multicentre, double-blind, randomized, vehicle-controlled study in patients with photodamaged facial skin.

BACKGROUND: Topical tazarotene has been shown to offer efficacy in ameliorating multiple effects of photodamage. OBJECTIVES: To evaluate the histological effects of tazarotene cream on photodamaged skin. METHODS: In this multicentre, double-blind, randomized, vehicle-controlled study, 50 patients with photodamaged facial skin (at least mild fine wrinkling and mottled hyperpigmentation, with at least one of these being moderate) were randomized to apply tazarotene 0.1% cream or vehicle cream to their face, once daily for 24 weeks. RESULTS: Blinded assessments showed that tazarotene was less likely than vehicle to be associated with an increase in keratinocytic and melanocytic atypia, and more likely than vehicle to be associated with a reduction in atypia. Between-group comparisons in distribution of change from baseline categories of severity were in favour of tazarotene (P = 0.055 for keratinocytic atypia, P = 0.034 for melanocytic atypia, and P < 0.001 for the number of granular cell layers). Compared with vehicle, tazarotene was associated with an increase in epidermal polarity (P = 0.008) and epidermal thickness (P = 0.012), and a tendency for stratum corneum compaction. Tazarotene was also associated with widened intercellular spaces (reported as epidermal oedema) relative to vehicle (P < 0.001). CONCLUSIONS: Treatment of photodamaged skin with tazarotene is associated with an amelioration of keratinocytic and melanocytic atypia, an improvement in epidermal polarity, and an increase in epidermal thickness.

Adult↗

PubMed2001

A pilot study to determine the effect of tazarotene gel 0.1% on steroid-induced epidermal atrophy.

BACKGROUND: Repeated applications of a corticosteroid can induce epidermal atrophy. This study was performed to investigate whether the adjunctive use of tazarotene gel 0.1% might help to minimize the development of steroid-induced epidermal atrophy. METHODS: Each of 24 healthy volunteers received the following six treatments (applied 6 days per week for 4 weeks), which were randomized to each of six sites on their forearms: no treatment, tazarotene vehicle, tazarotene vehicle + tazarotene gel 0.1%, diflorasone diacetate 0.05% ointment, diflorasone diacetate 0.05% ointment + tazarotene vehicle, or diflorasone diacetate 0.05% ointment + tazarotene gel 0.1%. RESULTS: The mean epidermal thickness was increased by 20% (NS) and 62% (P < or = 0.0005) after applications of tazarotene vehicle and tazarotene gel 0.1%, respectively. Application of diflorasone diacetate reduced the mean epidermal thickness by 43% (P < or = 0.0005). Concomitant application of tazarotene gel 0.1% with diflorasone diacetate did not entirely prevent atrophy, but was shown to ameliorate 37% of the epidermal atrophy induced by diflorasone diacetate alone (P < or = 0.003 compared with steroid monotherapy). CONCLUSIONS: Tazarotene gel 0.1% significantly reduces epidermal atrophy induced by diflorasone diacetate 0.05% ointment.

Adrenal Cortex Hormones↗

PubMed2001

The combination formulation of clindamycin 1% plus benzoyl peroxide 5% versus 3 different formulations of topical clindamycin alone in the reduction of Propionibacterium acnes. An in vivo comparative study.

BACKGROUND: Isolates of Propionibacterium acnes resistant to one or more anti-acne antibiotics (most commonly erythromycin) are being increasingly reported, and the emergence of resistant strains can be associated with therapeutic failure of topical treatment. OBJECTIVE: Comparison of the in vivo effectiveness of the combination of clindamycin 1% plus benzoyl peroxide 5% in a gel formulation to that of each of 3 clindamycin 1% preparations (gel, lotion, and solution) with respect to reduction in counts of P. acnes cultured from the foreheads of healthy volunteers. METHODS: The effects of treatment with the 4 study drugs were compared in an open-label study. Cultures were collected before, after 1 week and after 2 weeks of treatment. RESULTS: Treatment with the combination formulation resulted in a 99.8% (> 2 logs) reduction in total propionibacterial numbers after 1 week of therapy compared with 30 to 62% (< 1 log) decreases for the different formulations of topical clindamycin alone. By the end of week 2, the combination had decreased P. acnes counts by more than 99.9% (> 3 logs) relative to reductions of from 88 to 95% (< or > 1 log) for the single agent formulations. CONCLUSIONS: Under the conditions of the present study, the combination of clindamycin 1% plus benzoyl peroxide 5% gel produced more rapid and highly significant reductions in P. acnes compared with formulations containing clindamycin alone.

Adolescent↗

PubMed1997

The spectral dependence for UVA-induced cumulative damage in human skin.

The wavelength dependence for UVA-induced cumulative damage was investigated in human skin. Epidermal changes (stratum corneum thickening, viable epidermal thickening sunburn cell production), as well as dermal alterations (lysozyme deposition, inflammation), were used as indices of cumulative photoperturbation. UVA wavelengths between 320 nm and 345 nm were more effective than longer wavelengths (360-400 nm) in inducing viable epidermal thickening. Similarly, the shorter wavelengths (320-345 nm) elicited more sunburn cells, although these differences did not reach statistical significance. All UVA bands were equally effective in inducing the dermal markers. At equal fluences, wavelengths > 400 nm produced no measurable cutaneous alterations. These findings suggest that (i) chronic epidermal and dermal damages have different spectral dependence and (ii) the action spectrum for dermal damage in the UVA is broad, extending up to 400 nm, and is different from the acute erythema spectrum in humans.

Adolescent↗

PubMed1993

An ultraviolet radiation action spectrum for immediate pigment darkening.

The wavelength dependence for immediate pigment darkening (IPD) was investigated by exposing the midback skin of volunteers to a series of incremental fluences of narrow waveband radiation isolated by band-pass filters in the 310-400 nm region. The threshold IPD fluence for each waveband was determined by visual assessment of the skin responses immediately after each exposure. The action spectrum, constructed from the mean threshold fluences, was broad and extended from 320 nm to 400 nm with a peak at around 340 nm. No IPD could be evoked at 310 nm, even after erythemogenic fluences. The spectrum was similar in each of the three skin types investigated (III, IV, V). The broad nature of the action spectrum within the UVA region suggests that IPD may serve as an alternative endpoint for measuring photoprotection against these wavelengths.

Adult↗

PubMed1992

Effects of topical ammonium lactate on cutaneous atrophy from a potent topical corticosteroid.

BACKGROUND: Topical corticosteroids produce atrophic changes in skin, including thinning of the epidermis and decrease in dermal ground substance. We observed that 12% ammonium lactate produced an increase in the thickness of epidermis and increased amounts of dermal glycosaminoglycans. OBJECTIVE: Our purpose was to determine whether 12% ammonium lactate could minimize cutaneous atrophy produced by a potent topical corticosteroid. METHODS: Clobetasol propionate, 12% ammonium lactate, and both agents were repetitively applied under occlusive patches as well as in open patches on the forearms of human volunteers for 3 to 4 weeks. Biopsy specimens were analyzed for thickness of the epidermis and dermal glycosaminoglycans by image analysis. RESULTS: Twelve percent ammonium lactate produced a significant sparing of atrophy in both the epidermis and dermis without any influence on the bioavailability or antiinflammatory properties of the corticosteroid. CONCLUSION: Twelve percent ammonium lactate may be useful in mitigating the adverse effects of corticosteroid on skin.

Administration, Topical↗

PubMed1990

Persistent light reactivity from systemic quinine.

A 41-year-old black female with psoriasis developed photosensitivity and a Koebner reaction while receiving phototherapy. She had been receiving oral quinine intermittently for muscle cramps. Photobiological evaluation revealed a strongly positive photopatch test to quinine sulfate and a marked persistent reduction in the minimal erythema dose to solar-simulated radiation in the uninvolved skin. There were no abnormal reactions to UVA. The photosensitivity is still present 3 years after the withdrawal of quinine. These features are similar to those observed previously in persistent light reactors to topical photosensitizers.

Adult↗

PubMed1988

Wavelength dependence for DNA synthesis inhibition in hairless mouse epidermis.

Exposure of mammalian skin to ultraviolet radiation (UVR) results in a transient inhibition of scheduled DNA synthesis. The wavelength dependence for this response was investigated in the epidermis of albino hairless mice. Groups of animals were exposed to narrow wavebands of UVR (HPBW 6.6 nm) from a monochromator in the 260-335 nm range. A dose-dependent inhibition of DNA synthesis was observed following exposure to all test wavebands except that centered at 335 nm. An action spectrum constructed from dose-response regression lines showed peak effectiveness at 290 nm. This spectrum bears a close resemblance to published action spectra for the induction of pyrimidine dimers in vivo, suggesting that DNA is the primary chromophore for both events. The DNA synthesis inhibition spectrum bears little resemblance to a published therapeutic action spectrum for the clearing of psoriasis.

Animals↗

PubMed1987

Comparison of methods for assessing photoprotection against ultraviolet A in vivo.

Photoprotection against ultraviolet A (UVA) by three sunscreens was evaluated in humans, with erythema and pigmentation used as end points in normal skin and in skin sensitized with 8-methoxypsoralen and anthracene. The test sunscreens were Parsol 1789 (2%), Eusolex 8020 (2%), and oxybenzone (3%). UVA was obtained from two filtered xenon-arc sources. UVA protection factors were found to be significantly higher in sensitized skin compared with normal skin. Both Parsol and Eusolex provided better and comparable photoprotection (approximately 3.0) than oxybenzone (approximately 2.0) in sensitized skin, regardless of whether 8-methoxypsoralen or anthracene was used. In normal unsensitized skin, Parsol 1789 and Eusolex 8020 were also comparable and provided slightly better photoprotection (approximately 1.8) than oxybenzone (approximately 1.4) when pigmentation was used as an end point. The three sunscreens, however, were similar in providing photoprotection against UVA-induced erythema. Protection factors obtained in artificially sensitized skin are probably not relevant to normal skin. It is concluded that pigmentation, either immediate or delayed, is a reproducible and useful end point for the routine assessment of photoprotection of normal skin against UVA.

Adolescent↗

PubMed1985

UV suppression of mast cell-mediated wealing in human skin.

Prior exposure of normal skin to subthreshold doses of UVR from a "UVA" phototherapy cabinet resulted in a small but significant reduction of the wealing response to intradermally injected codeine phosphate, a mast cell degranulating agent. The flare component of the reaction was not affected, nor were the responses to intradermally injected histamine. Both UVA and UVB from banks of filtered fluorescent tubes appeared to produce a similar but less pronounced effect. Dose-response studies revealed that the inhibition of mast cell-mediated wealing required a certain cumulative threshold dose of UVR (about 35 J/cm2 UVA + 20 mJ/cm2 UVB). The observed reduction in wealing could not be entirely explained by differences in the content of tissue histamine. It is concluded that repeated exposure to a broad range of UV wavelengths can depress the response of mast cells in vivo to degranulating agents by an unknown mechanism. This finding may have relevance to some of the observed therapeutic effects of phototherapy in certain inflammatory dermatoses and especially cutaneous mast cell disorders.

Adult↗

PubMed1982

Experimental photoallergic contact dermatitis: a mouse model.

We have induced photoallergic contact dermatitis in mice to 3,3',4',5 tetrachlorosalicylanilide (TCSA), chlorpromazine and 6-methylcoumarin. These compounds are known to produce photoallergic contact dermatitis in humans. The photoallergic contact dermatitis reaction in the mouse is immunologically specific viz. mice photosensitized to TCSA react, by photochallenge, to that compound and not to chlorpromazine, and conversely. The reaction requires UVA at both sensitization and challenge. It appears to be T-cell mediated in that it can be passively transferred to syngeneic mice by lymph node cells from actively sensitized mice, the histology of the reactions resembles that of classic allergic contact dermatitis in mice, challenge reactions are seen at 24 but not at 4 hr, and photoallergic contact dermatitis can be induced in B-cell deficient mice. The availability of a mouse model for the study of photo-ACD will facilitate the identification of pertinent control mechanisms and may aid in the management of the disease. It is likely that a bioassay for photoallergens of humans can be based on this mouse model.

Animals↗

PubMed1979

Persistent photosensitivity following occupational exposure to epoxy resin.

Persistent photosensitivity developed in eight men following occupational exposure to hot epoxy resin fumes. The condition was limited to sites the resin contacted. Small doses of ultraviolet-A light (2 to 5 joules/sq cm) evoked abnormal reactions consisting of erythema, edema, and papules in the clinically involved skin. Positive photopatch tests to epoxy resin were observed in four subjects, and to 4, 4'-isopropylidenediphenol (Bisphenol A) in all. The photosensitivity is most probably due to photocontact allergy to 4,4'-isopropylidenediphenol or to a closely related chemical.

Adult↗

PubMedDate not supplied

Use of topical corticosteroid pretreatment to reduce the incidence and severity of skin reactions associated with testosterone transdermal therapy.

Local skin reactions at the application site are the most common adverse events associated with the testosterone transdermal delivery (TTD) systems used to treat postpubertal hypogonadism in males. This open-label, controlled pilot study was conducted to determine whether topical pretreatment with triamcinolone acetonide 0.1% cream might be useful in reducing the incidence and/or severity of chronic skin irritation when used in healthy volunteers receiving TTD systems. Adult male volunteers wore three topical systems, which were applied to the upper back daily (Monday through Friday) for 6 weeks: (1) TTD with no pretreatment of application site; (2) TTD with pretreatment of application site using triamcinolone acetonide 0.1% cream; and (3) an inactive occlusive dressing (control). On Monday through Thursday, systems were removed 24 hours after application. Patches applied on Friday were worn continuously for 72 hours until their removal on Monday. Skin reactions were graded on a scale from 0 to 4 (0 = none, 4 = severe) and were assessed daily by research personnel, beginning at the time of system removal (assessment 1) and on the two subsequent clinic visits (assessments 2 and 3). All skin irritation scores of all subjects were totaled for each treatment regimen to obtain a cumulative score per treatment regimen. The cumulative scores were also analyzed by assessment time and study week (weeks 1-6). Eighty-two subjects were enrolled in the study, and 65 completed the 6-week treatment course. Mean age of subjects was 24 years (range, 18-69 years), and mean weight was 79.0 kg (range, 58.9-127.3 kg). All subjects were white males. At assessment 1, pretreatment with triamcinolone acetonide 0.1% cream (compared with no pretreatment) was associated more often with scores of 0 (no erythema), with comparable occurrences of mild skin irritation, and with fewer occurrences of moderate erythema. At all three assessments, more subjects had lower cumulative scores with pretreatment than without pretreatment. At every assessment and in each week of the study, total weekly cumulative skin irritation scores were also lower with pretreatment than without pretreatment. No adverse experiences other than skin irritation were reported. Results of this study suggest that in patients using TTD systems, the incidence and severity of skin irritation at application sites may be reduced through pretreatment with triamcinolone acetonide 0.1% cream.

Administration, Cutaneous↗