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Biomedical subjects

H I Maibach

Publications and source records attributed to H I Maibach.

At least 19 recordsLinked to original sources
PubMed1992

In vitro percutaneous absorption of cadmium from water and soil into human skin.

The objective was to determine percutaneous absorption of cadmium as the chloride salt from water and soil into and through human skin. Soil (Yolo County 65-California-57-8) was passed through 10-, 20-, and 48-mesh sieves. Soil retained by 80 mesh was mixed with radioactive cadmium-109 at 13 ppb. Water solutions of cadmium-109 at 116 ppb were prepared for comparative analysis. Human cadaver skin was dermatomed to 500-microns, and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/hr flow rate) for a 16-hr skin application time. Cadmium in water (5 microliters/cm2) penetrated skin to concentrations of 8.8 +/- 0.6 and 12.7 +/- 11.7% of the applied dose from two human skin sources. Percentage doses absorbed into plasma were 0.5 +/- 0.2 and 0.6 +/- 0.6%, respectively. Cadmium from soil (0.04 g soil/cm2) penetrated skin at concentrations of 0.06 +/- 0.02 and 0.13 +/- 0.05% for the two human skin sources. Amounts absorbed into plasma were 0.01 +/- 0.01 and 0.07 +/- 0.03%. Most of the nonabsorbed cadmium was recovered in the soap and water skin surface wash. Binding of cadmium from water to soil was greater than binding from water to powdered human stratum corneum, supporting the lower absorption from soil than from water. Short-term exposure of cadmium in water to human skin for 30 min (bath or swim) resulted in skin uptake, which upon further perfusion (48 hr), absorbed into the plasma receptor fluid (systemic). Cadmium in soil was increased from 6.5 to 65 ppb.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1992

In vivo percutaneous absorption of hydrocortisone: multiple-application dosing in man.

Percutaneous absorption of hydrocortisone was measured in six healthy adult men from whom informed consent had been obtained. The study compared a single topical dose to multiple-topical dose treatments (one vs three applications) on the same day. 14C-Labeled hydrocortisone in acetone was applied to 2.5 cm2 of ventral forearm skin and protected with a nonocclusive polypropylene chamber. The amount of 14C measured in urine collected over 7 days was used to determine hydrocortisone absorption. The treatments, performed 2 to 3 weeks apart, each utilized adjacent sites on the same individuals. A single dose of 13.33 micrograms/cm2 delivered 0.056 microgram/cm2 of hydrocortisone through the skin. When the single dose was tripled to 40 micrograms/cm2, the amount delivered through the skin increased by nearly three times, from 0.056 to 0.140 micrograms/cm2; the expected delivery was 3 x 0.056 micrograms/cm2 = 0.168 microgram/cm2. Three serial doses of 13.33 micrograms/cm2 (total, 40 micrograms/cm2) were also expected to deliver 0.168 micrograms/cm2 with or without soap and water washing between doses, but the observed amount of hydrocortisone delivered through the skin significantly exceeded our expectations. This indicates that multiple-dosing treatments resulted in a significant increase in bioavailability. It is postulated that increased vehicle application and washing dissolved and mobilized previously dosed hydrocortisone and increased bioavailability.

Administration, Cutaneous↗
PubMed1992

Percutaneous absorption of drugs.

The skin is an evolutionary masterpiece of living tissue which is the final control unit for determining the local and systemic availability of any drug which must pass into and through it. In vivo in humans, many factors will affect the absorption of drugs. These include individual biological variation and may be influenced by race. The skin site of the body will also influence percutaneous absorption. Generally, those body parts exposed to the open environment (and to cosmetics, drugs and hazardous toxic substances) are most affected. Treating patients may involve single daily drug treatment or multiple daily administration. Finally, the body will be washed (normal daily process or when there is concern about skin decontamination) and this will influence percutaneous absorption. The vehicle of a drug will affect release of drug to skin. On skin, the interrelationships of this form of administration involve drug concentration, surface area exposed, frequency and time of exposure. These interrelationships determine percutaneous absorption. Accounting for all the drug administered is desirable in controlled studies. The bioavailability of the drug then is assessed in relationship to its efficacy and toxicity in drug development. There are methods, both quantitative and qualitative, in vitro and in vivo, for studying percutaneous absorption of drugs. Animal models are substituted for humans to determine percutaneous absorption. Each of these methods thus becomes a factor in determining percutaneous absorption because they predict absorption in humans. The relevance of these predictions to humans in vivo is of intense research interest. The most relevant determination of percutaneous absorption of a drug in humans is when the drug in its approved formulation is applied in vivo to humans in the intended clinical situation. Deviation from this scenario involves the introduction of variables which may alter percutaneous absorption.

Animals↗
PubMed1992

Objective prick test evaluation: non-invasive techniques.

Prick test reactions are evaluated and quantified, comparing visual assessment with two non-invasive techniques: remittance spectroscopy and pulsed ultrasound for erythema and skin thickness measurements. Different information is provided by the two methods. Remittance spectroscopy discriminates well between negative and positive reactions (+ or ++), while failing to differentiate stronger reactions, where edema is a prominent feature. The latter reactions are better evaluated by skin thickness measurements, which, on the contrary, are less sensitive in revealing small skin thickness increases in weak reactions.

Adult↗
PubMed1979

Black and white human skin differences.

This review of black and white human skin differences emphasizes the alleged importance of factors other than the obvious, i.e., skin color. Physicochemical differences and differences in susceptibility to irritants and allergens suggest a more resistant black than white skin. Differences appear to exist in the frequency of which several skin diseases occur among blacks and whites. A striking feature in this literature is the disagreement between authors. Common for much of this information is difficulty of interpretation, because of socioeconomic influences and other environmental factors.

Africa↗
PubMed1979

Scabies, a current pandemic.

Scabies, caused by the itch mite and transmitted by skin-to-skin contact, is being seen in pandemic proportion. In the United States this infestation is seen in patients of all ages and socioeconomic levels. Scabies is often misdiagnosed, and the classic form occurs less frequently in the current cycle. Differential diagnosis includes most pruritic dermatoses. Diagnosis should be made with certainity, preferably by identification of the mite, before therapy is begun. Modern scabicides are high effective.

Acute Disease↗
PubMed1979

Evaporation of diethyltoluamide from human skin in vivo and in vitro.

Relative evaporation and penetration of the insect repellent, N,N-diethyl-m-toluamide, has been measured by 3 methods, 2 in vivo and 1 in vitro. The evaporation rate 30 min after application was found to be similar by all 3 methods. At an applied dose of 0.25 microgram/cm2, 9.6% in vivo and 9.7% in vitro evaporated from the skin in the first hour after application. Although the techniques used produced similar results in vivo and in vitro for diethyltoluamide, studies are being conducted to further elucidate kinetics of loss by evaporation.

Benzamides↗
PubMed1979

Quantitative microbiology of human vulva.

The microbial flora of the vulva is described and compared with the flora of the forearm by utilizing the detergent scrub method. Microbial counts were higher on the vulva (2.8 x 10(6)/cm2) than on the forearm (6.4 x 10(2)/cm2). Lipophilic diphtheroids, coagulase negative staphylococci, micrococci, non-lipophilic diphtheroids and lactobacilli formed the dominant flora of the vulva. Streptococci, Gram negative rods and yeasts were also noted. The highest incidence of S. aureus was noted on the vulva (67%) followed by perianal (30%), nose (30%), and the forearm (11%).

Adult↗
PubMed1979

Contact dermatitis and gastrointestinal symptoms from hydroxyethylmethacrylate.

A laboratory technician developed allergic contact dermatitis to hydroxyethylmethacrylate associated with nausea, diarrhoea and persistent paresthesiae of the fingertips. The gastrointestinal symptoms were reproduced by patch testing. Hydroxyethylmethacrylate was demonstrated to pass through vinyl gloves. Cross reactions occurred to methyl-, ethyl-, propyl- and isopropylmethacrylate but not to butyl- or isobutylmethacrylate.

Acrylates↗
PubMed1979

Detection of environmental depigmenting substances.

We systematically screened the depigmenting capacity of several phenols, catechols and organic antioxidants. Clear-cut depigmentation was achieved with monomethyl ether of hydroquinone (MMH) and tertiary butyl catechol (TBC) using black guinea pigs and black mice as animal models. A goal was to establish a reliable in vivo method to demonstrate or to predict the depigmenting action of chemicals on mammalian melanocytes. There was no universal solvent or optimal body site, although all tested areas could be depigmented. Irritation induced by some vehicles and test materials produced false positive responses. False negative responses with known depigmenting chemicals were observed. Utilizing these observations, we propose a model for screening medicinal and industrial chemicals for depigmenting capacity.

Animals↗
PubMed1979

Human cutaneous vulvar reactivity to irritants.

To better understand the cutaneous reactivity of vulvar skin, two chemical irritants were applied topically to 21 subjects. The forearm of each subject served as a comparative control. Test sites remained open and were read at 24 hours. A significantly increased response to the irritants was noted on the vulvar skin.

Administration, Topical↗