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Biomedical subjects

H Maibach

Publications and source records attributed to H Maibach.

At least 19 recordsLinked to original sources
PubMed1992

Effect of occlusive dressings on the stratum corneum water holding capacity.

Occlusion of the skin is used in clinical dermatology to promote wound healing and to increase the transcutaneous penetration of topically applied drugs. These effects are related to the degree of occlusion exerted and depend on the physicochemical nature of the dressing. We have evaluated the effects of four different materials on the skin barrier and the stratum corneum water holding capacity (WHC) using the Plastic Occlusion Stress Test (POST). The following materials were compared: hydrocolloid dressing, polyurethane film, polyethylene film, and a plastic chamber. These devices were applied on the volar forearm for 24 hours in 10 healthy volunteers (mean age 32 +/- 4 years). Upon their removal, the stratum corneum WHC, measured as skin surface water loss (SSWL), was recorded continuously for 25 minutes using an Evaporimeter. SSWL decay curves showed significant differences between the occlusive materials (analysis of variance, p less than 0.01). Higher SSWL values were recorded in sites occluded with the plastic chamber, whereas the polyurethane film resulted in poor occlusive capacity. Hydrocolloid dressing and polyethylene gave similar responses with higher WHC values compared to polyurethane (p less than 0.05). The relevance of these findings to clinical dermatology in terms of wound healing and drug absorption is discussed.

Adult↗
PubMed1992

Ultraviolet B dose-dependent inflammation in humans: a reflectance spectroscopic and laser Doppler flowmetric study using topical pharmacologic antagonists on irradiated skin.

Normal skin responds acutely to ultraviolet (UV) light exposure with complex inflammatory mechanisms. In the present study UVB irradiation ranging from subclinical erythema doses to twice the minimal erythema dose (24 mJ/cm2 to 96 mJ/cm2) was delivered to the skin of 8 volunteers. Pre-irradiated sites were immediately afterwards exposed to a 24-h occlusive patch containing 1 of 4 anti-inflammatory agents or vehicle control. The resultant change in erythema (vascular reaction) was measured objectively using laser Doppler flowmetry (LDF) and reflectance spectroscopy (RS). The 4 anti-inflammatory compounds reduced the UVB-induced vascular reactions in different and dose-dependent ways. Betamethasone-17-valerate and diphenhydramine were most effective at the 24 mJ/cm2 dose site and indomethacin and acetylsalicylic acid were more effective at sites > or = 48 mJ/cm2. Ranking the reduction in oxygenized hemoglobin (OH) content was as follows: betamethasone-17-valerate (OH reduction = 37.4%) > indomethacin (OH reduction = 21.5%) > acetylsalicylic acid (ASA) (OH decrease = 21.0%) > diphenhydramine (OH reduction = 18.4%). Using LDF, the total ranking of the cutaneous blood flow (BF) reduction was: indomethacin (BF reduction = 39.7%) > betamethasone-17-valerate (BF reduction = 32.7%) > acetylsalicylic acid (BF decrease = 17.5%) > diphenhydramine (BF reduction = 12.3%). Diphenhydramine significantly reduced erythema only at the lowest irradiation dose (24 mJ/cm2) and the decrease in OH was associated with an increased amount of deoxygenized hemoglobin (DOH). A similar slight venous dilatation was present at acetylsalicylic acid-exposed sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1991

Controlled release of benzoyl peroxide from a porous microsphere polymeric system can reduce topical irritancy.

Skin absorption of benzoyl peroxide from a topical lotion containing freely dispersed drug was compared with that from the same lotion in which the drug was entrapped in a controlled-release styrene-divinylbenzene polymer system. In an in vitro diffusion system, statistically significant (p = 0.01) differences were found in the content of benzoyl peroxide in excised human skin and in percutaneous absorption. In vivo, significantly (p = 0.002) less benzoyl peroxide was absorbed through rhesus monkey skin from the polymeric system. This controlled release of benzoyl peroxide to skin can alter the dose relation that exists between efficacy and skin irritation. Corresponding studies showed reduced skin irritation in cumulative irritancy studies in rabbits and human beings, whereas in vivo human antimicrobial efficacy studies showed that application of the formulations containing entrapped benzoyl peroxide significantly reduced counts of Propionibacterium acnes (p less than 0.001) and aerobic bacteria (p less than 0.001) and the free fatty acid/triglyceride ratio in skin lipids. These findings support the hypothesis that, at least for this drug, controlled topical delivery can enhance safety without sacrificing efficacy.

Administration, Cutaneous↗
PubMed1991

In vivo transcutaneous penetration of nicotinates and sensitive skin.

Proclivity to develop irritant reactions and transcutaneous penetration of nicotinates has been investigated in 20 subjects of both sexes, divided into reactors and nonreactors on the basis of the responses to irritant stimuli. 1% sodium lauryl sulphate (patch application for 24 h) and 5% lactic acid in aqueous solutions were used to detect chemical and sensory (subjective) irritation. The vasodilatation induced was measured using a chromameter for 1 h after topical application of the chemical. The area-under-the-curve response and the peak response was used to assess the in vivo penetration of methyl nicotinate (10 mM in aqueous solution). Significant differences were found between reactors and non-reactors. Non-reactors showed a significantly decreased area-under-the-curve response and peak response to methyl nicotinate compared to reactors. Nicotinate-induced vasodilatation has been used as a model to study transcutaneous penetration of chemicals; the correlation between increased penetration of nicotinates and skin hyperreactivity to irritant substances may suggest an increased transcutaneous penetration of water-soluble chemicals in individuals with sensitive skin.

Administration, Cutaneous↗
PubMed1991

Second-generation tetracyclines, a dermatologic overview: clinical uses and pharmacology.

Tetracycline and its derivatives are frequently used in the treatment of acne, soft tissue bacterial infections, Lyme disease (borreliosis), chlamydial-infections, and respiratory tract infections. Several pharmacologic and microbiological properties of these antibiotics make them particularly suitable for such uses. First-generation tetracyclines have long been in use; however, the second-generation tetracyclines minocycline, doxycycline hyclate, and doxycycline monohydrate have also become widely prescribed, and can offer advantages to the dermatologist over tetracycline. This paper reviews the important pharmacologic and microbiological characteristics of these three commonly used second-generation tetracyclines, and their clinical applications in dermatology.

Adult↗
PubMed1991

A time-correlation study of ultraviolet B-induced erythema measured by reflectance spectroscopy and laser Doppler flowmetry.

Ultraviolet B (UVB)-irradiated skin pigmentation was quantified using 2 objective and noninvasive techniques. Ten healthy volunteers were exposed to increasing UVB doses in the interval from 6 mJ/cm2 to 120 mJ/cm2 and the resultant vascular and pigmentary changes were evaluated using laser Doppler flowmetry (LDF) and reflectance spectroscopy (RS). Measurements were made 0.25 h, 1 h, 4 h, 8 h, 24 h, 72 h and 192 h post-irradiation. Visual scores were determined 24 h post-irradiation. Both RS and LDF revealed an early and rapid erythematous response to UVB irradiation, peaking between 8 h and 24 h, with no single UVB dose showing any significant increase until 4 h post-irradiation. LDF showed a peak increase in blood flow at 8 h post-irradiation for sites with low UVB exposure (less than or equal to 36 mJ/cm2). Doses greater than or equal to 42 mJ/cm2 showed maximal increase at 24 h. After this increase in blood flow, a slow normalization began that was not complete at 192 h post-irradiation at sites exposed to greater than or equal to 60 mJ/cm2. The present RS analysis is able to distinguish between oxygenized (OH) and deoxygenized hemoglobin (DOH). The only significant increase in DOH was found for the averaged 6 mJ/cm2 and 12 mJ/cm2 UVB dose sites 24 h after irradiation. OH peaked 24 h post-irradiation and resolution was still incomplete after 192 h. RS revealed no dose, as did the LDF, below which the vascular response peaked earlier. LDF measures dermal blood flow and RS measures hemoglobin content in the skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

In vivo hydration and water-retention capacity of stratum corneum in clinically uninvolved skin in atopic and psoriatic patients.

Hydration and the water-retention capacity of stratum corneum have been investigated in uninvolved psoriatic and atopic skin and compared with that of healthy controls. Thirty-three subjects of either sex and matched for age entered the study. The subjects were free from all signs of skin disease and skin dryness. Hydration was evaluated by means of transepidermal water loss and skin capacitance measurements. Water-retention capacity was investigated using the plastic occlusion stress test. Atopic skin differed significantly from uninvolved psoriatic and control skin which had a reduced water content and an increased transepidermal water loss. Furthermore, the skin surface water loss profile representing the stratum corneum water-retention capacity was significantly lower in normal atopic skin. The data suggest that clinically normal skin may be functionally abnormal, resulting in a defective barrier that could lead to higher risk of irritant or contact dermatitis.

Adult↗
PubMed1989

Cutaneous reactive hyperaemia: racial differences induced by corticoid application.

The postocclusive hyperaemic reaction before and after a single 1 h application of a potent corticoid (clobetasol 0.05% in ointment) was recorded by means of laser Doppler velocimetry in order to elucidate different racial responses in skin vasoconstriction. Fourteen young male subjects entered the study (eight Caucasians, six Blacks). Reactive hyperaemia was recorded after 4 min of occlusion of the forearm blood flow. The following parameters of the hyperaemic reaction were investigated: area under the curve response, peak response, rise of blood flow slope to peak and decay of blood flow slope after peak. Different responses were recorded in the Black subjects after the vasoconstrictive stimulus compared to the Caucasians, namely: decreased area under the curve response (P less than 0.04); decreased peak response (P less than 0.01); decreased decay slope after peak blood flow (P less than 0.04). These data are consistent with a different reactivity of blood vessels in black skin and possibly not related to the transcutaneous penetration of the chemical compound.

Adult↗
PubMed1988

Restriction of bacterial growth under commercial catheter dressings.

The effect on the normal cutaneous flora after iodine and alcohol disinfection of the skin of three commercially available moisture-permeable polyurethane dressings was compared with that of a gauze-and-tape dressing. Dressings also were evaluated clinically for membrane adhesion and skin erythema, pruritus, hyperpigmentation, vesiculitis, and tenderness. Each of 50 healthy volunteers and 49 long-term inpatients, 25 of whom were receiving antibiotic therapy, received simultaneously on their volar forearm patches of Op-Site, Tegaderm, Uniflex, and gauze dressings. Controls consisted of one exposed skin site and one covered with moisture-retaining vinylidene film (Saran Wrap). Although after 3 days of adhesion, commercial dressings prevented indigenous flora from returning to normal population densities, no significant quantitative differences were found between them and the gauze-and-tape dressing. Generally, all clinical dressings maintained normal flora at one tenth the population of the uncovered site; the Saran Wrap control supported 100-fold more bacteria than the exposed site. No differences were discovered in the levels of gram-negative bacteria, or among patient groups and between patients and healthy subjects, except for the lower incidence of erythema and itching among patients compared with healthy subjects.

Adult↗
PubMed1988

Study of irritant contact dermatitis produced by repeat patch test with sodium lauryl sulfate and assessed by visual methods, transepidermal water loss, and laser Doppler velocimetry.

Eleven subjects received patch tests with 2% sodium lauryl sulfate on a total of 34 anatomic sites. The irritant effect was monitored by visual means, laser Doppler velocimetry, and measurement of transepidermal water loss. After 1 week, repeat patch tests with 2% sodium lauryl sulfate were performed on the same site, and the effect was monitored as before. Although the skin had returned to normal or near normal before the repeat patch test, an augmented response to irritation was generally seen after the repeat patch test, particularly in transepidermal water loss, which showed an augmented response in 29 of the 34 anatomic sites. The clinical implications regarding the healing of contact irritant dermatitis are discussed.

Adolescent↗
PubMed1985

The Finn chamber methylene blue ring.

Metallic aluminium and methylene blue applied to human skin interact and give a strong resistant coloration, obtained neither with methylene blue itself nor with other dyes. The reaction proves that aluminium is not an inert material and that the aluminium in Finn chambers can be expected to interact with other patch test substances.

Aluminum↗
PubMed1985

Clonidine: irritant and allergic contact dermatitis assays.

Clonidine in petrolatum, clonidine transdermal device, and its placebo device were assayed for relative irritancy potential (21-day cumulative irritancy assay) and allergic contact dermatitis potential (Draize repeat insult patch test assay). Both clonidine in petrolatum and the clonidine transdermal device appear to be of minimal irritancy potential. Only the clonidine device demonstrated, in the Draize assay (and in clinical trials), allergic contact dermatitis potential. Its relatively delayed onset of demonstration of allergic contact sensitization in clinical trials requires investigation as to mechanism.

Administration, Topical↗
PubMed1985

Aluminium in Finn chambers reacts with cobalt and nickel salts in patch test materials.

Aluminium has a greater affinity for electrons than cobalt and nickel. Therefore, cobalt and nickel ions would be expected to exchange with metallic aluminium in Finn chambers. This theory has been proven to be valid, as shown in 2 series of experiments: first, cobalt and nickel salt solutions (0.25 M) etch a metallic aluminium surface; secondly, aluminium Finn chambers kept in 10(-3) M nickel salt solutions significantly reduce the concentration of dissolved nickel. Dichromate solutions do not etch an aluminium metal surface significantly. Petrolatum, which is routinely used as vehicle in standard patch tests, probably protects the aluminium of Finn chambers from the interaction of cobalt and nickel salts. The interaction may have significance in tests with solutions.

Aluminum↗
PubMed1984

Lindane binding to sections of human skin: skin capacity and isotherm determinations.

Human autopsy skin was sliced into three sections; an outer epidermis-rich layer, a middle dermis layer, and an inner dermis and subcutaneous fat layer. Each slice was bathed in lindane solutions over a 50-fold concentration range for 48 h at 37 degrees C. Lindane uptake by the skin was extensive (less than 90%) for all concentrations and all skin slices. Equilibrium dialysis with lindane at 37 degrees C for 24 h showed binding affinities by the skin sections to exceed 98%. The binding constants of the outer skin section (epidermis-rich) were higher than those of the middle and inner sections. The binding attraction for lindane by United States Pharmacopeia (USP) human plasma protein fraction (mean 90.5% bound) resulted in its competitive extraction from the skin slices in a three-compartment dialytic procedure. Since the least binding constants were in the middle and inner layers, and since lindane has a preference for plasma over skin, the two (inner skin and plasma) may combine to create the sink conditions necessary for lindane percutaneous absorption into the body. This plus the high epidermis capacity for lindane explains why in some instances (such as occlusion) high levels of lindane can be percutaneously absorbed.

Biological Transport, Active↗
PubMed1984

Deposition of 3,4,4'-trichlorocarbanilide on human skin.

For rinse-off products such as soaps, quantitating the deposition of ingredients left behind on the skin following rinsing may be important particularly if the ingredient is biologically active, e.g. germicides, perfumes. The residue comprises the major portion of material which is available for percutaneous penetration. A method is described for quantitating the deposition of the soap germicide, 3,4,4'-trichlorocarbanilide (TCC) as the result of direct application of bar soap on human skin. A soap pellet containing 1.5% [14C]TCC was gently rubbed on a small area of the volar forearm for 30 s. 90 s after soap application the site was thoroughly rinsed with water. After rinsing, 1.4% of the applied [14C]TCC, or 0.33 micrograms/cm2, remained on the treated site as determined by cellophane tape stripping followed by scintillation counting. The amount of TCC deposited from a simulated wash with a bar soap onto human skin is compared to the amount deposited onto the skin of other species.

Animals↗