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Biomedical subjects

J D Guin

Publications and source records attributed to J D Guin.

At least 37 records · Page 2Linked to original sources
PubMed1997

Patch testing for contact dermatitis.

Patch testing is perhaps not an exact science, but it is the best method available for identifying and confirming contact sensitivity. Illustrated step-by-step instructions for the procedure are presented, with helpful hints to avoid some of the pitfalls.

Dermatitis, Contact↗
PubMed1996

Comparative percutaneous absorption of lindane and permethrin.

BACKGROUND AND DESIGN: Because of the concern for potential neurotoxic effects (central nervous system excitation, convulsions) in the treatment of scabies using 1% lindane lotion, 5% permethrin cream has been suggested as an alternative scabicide. Using the finite dose technique, in vitro percutaneous absorption of 5% permethrin cream or 1% lindane lotion was measured in human and guinea pig skin following a single application. In vivo blood and brain levels of the scabicides were measured in guinea pigs following three daily applications of 5% permethrin cream or 1% lindane lotion. Permethrin and lindane levels were quantified by gas chromatography/mass spectroscopy. RESULTS: In vitro percutaneous absorption of the two scabicides was identical in guinea pig skin; however, human skin was 20-fold more permeable to lindane than to permethrin. In vivo guinea pig blood and brain levels of lindane were fourfold greater than permethrin levels. CONCLUSION: The risk for toxic effects, as assessed by systemic exposure during overuse conditions, is projected to be 40 to 400 times lower for 5% permethrin cream than for 1% lindane lotion.

Animals↗
PubMed1993

Quantitative vasoconstrictor assay for topical corticosteroids: the puzzling case of fluocinolone acetonide.

BACKGROUND: The validity of the vasoconstrictor test has been questioned because of the apparent nonequivalence of some generic corticosteroid products. OBJECTIVE: Our purpose was to determine the vasoconstrictor activity of a generic 0.025% fluocinolone acetonide ointment by two different methods, dilution by volume and dilution by area of application. METHODS: Vasoconstrictor activity on a visual 4-point scale was measured in 20 volunteers. Topical fluocinolone acetonide ointment (0.025%) was tested by comparing dilution by volume (1:1, 1:3, and 1:7) in petrolatum and dilution by area of application. Fluocinolone release from the diluted ointments was also measured with an in vitro method. RESULTS: Dilution by area gave the expected results, a decreasing average vasoconstrictor score; but dilution by volume did not. Both the 1:1 and 1:3 dilutions inexplicably showed greater activity than the full-strength product; this finding was similarly reflected in the in vitro studies that showed a greater rate of drug release from the 1:1 and 1:3 dilutions. CONCLUSION: Dilution by area provides a useful quantitative assay for comparative vasoconstrictor activity.

Adult↗
PubMed1993

Hand eczema herpeticum.

Eczema herpeticum consists of a primary herpes simplex virus infection superimposed on a pre-existing dermatosis. Localized forms of this condition also occur. A twenty-three-year-old woman showed a primary herpes simplex virus infection in the areas of her residual atopic hand eczema after contact with her eighteen-month-old son's oral cavity, which was infected with herpes simplex type I. Possible theories about pathogenesis include a temporary deficit in cell-mediated immunity, defective interleukin production, or persistent alteration of the affected skin. Use of acyclovir resulted in rapid clearing of the eruption. Herpes simplex virus infection should be considered in the differential diagnosis when a flare or vesiculation occurs in patients with atopic hand eczema.

Adult↗
PubMed1992

Aquagenic urticaria.

Aquagenic urticaria is a rare form of physical urticaria characterized by small follicular wheals with an erythematous flare upon exposure to water. We describe typical lesions in a seven-year-old boy with aquagenic urticaria, cholinergic urticaria, and symptomatic dermatographism, who responded to treatment with ultraviolet B and oral antihistamines.

Child↗
PubMed1991

Pathogenesis of onychoschizia (lamellar dystrophy).

Onychoschizia or lamellar dystrophy of the nails is common, especially in adult women, but little information is available about its cause. Most theories involve environmental factors, but supportive experimental data are scarce. Therefore we studied the in vitro nail changes produced by several organic solvents, detergents, water, other polar materials, and both acidic and basic solutions. Challenged and control fingernail clippings were examined grossly, microscopically, and by scanning electron microscopy at regular intervals. There was a progressive increase in severity with prolonged wetting and drying. By 3 weeks, scanning electron microscopy demonstrated unattached individual cells in empty spaces in which separation was more prominent. Basic solutions caused some softening, but layering (peeling) was seen only after repeated hydration and dehydration. Although other factors may influence onychoschizia, the typical changes can be produced in normal nails after a 21-day challenge of repeated exposure to water followed by dehydration. These findings suggest a probable cause for the condition and a logical approach to management.

Adult↗
PubMed1991

Making your own videotapes for patient instruction.

Producing your own videotapes can be both fun and clinically helpful. They are extremely effective for patient instruction and for obtaining informed consent. This article discusses the production, presentation, and effective use of videotapes in office practice.

Humans↗
PubMed1990

Magnolia grandiflora dermatitis.

A patient is described who had allergies to several sesquiterpene lactone-containing plants, but the reaction to Magnolia grandiflora was extremely severe. The condition was a chronic lichenified dermatitis that was unresponsive to treatment but cleared with protective measures. Primary allergy to Magnolia is rarely reported, even though some studies of cross-reactivity suggest that sensitivity is far from rare.

Clobetasol↗
PubMed1989

Bioequivalence (bioavailability) of generic topical corticosteroids.

A new, quantitative modification of the vasoconstrictor assay was used to measure bioavailability of generic topical corticosteroid products in two categories: betamethasone valerate 0.1% cream and triamcinolone 0.1% cream. Betamethasone valerate products could be separated into two distinct categories, and triamcinolone acetonide products could be grouped into three categories of activity. A survey of local pharmacies showed that generic substitution would be made for the prescribed brand of betamethasone valerate in 58% of cases and for the prescribed triamcinolone acetonide 75% of the time. Because of the prevalence of generic substitution of products that may not have equivalent bioavailability, some standardization of the bioavailability of topical products is needed.

Administration, Topical↗
PubMed1989

Erythroderma from systemic contact dermatitis: a complication of systemic gentamicin in a patient with contact allergy to neomycin.

A patient who was sensitive to potassium dichromate and neomycin showed a universal exfoliative erythroderma following intravenous gentamicin therapy. When his ear canals were later treated with a neomycin-containing topical medication, he reacted so severely that the skin of his ears was temporarily depigmented. Withdrawal of aminoglycoside antibiotics along with use of a topical steroid preparation under occlusion brought the eruption under control. Since approximately half of the persons with contact allergy to neomycin will also react to gentamicin, it seems unwise to treat such patients with other intravenous aminoglycosides that are closely related chemically. In our patient, multiple patch tests to other aminoglycosides caused positive reactions to all reagents containing a deoxystreptamine ring, but there was no reaction to streptomycin, which lacks that structure.

Aged↗
PubMed1988

The tanning salon: an area survey of equipment, procedures, and practices.

Because so little data are available on practices and procedures used by tanning salons, we studied, as customers, salons in a major city in Arkansas, the state where the practice began. We measured both ultraviolet A (UVA) and ultraviolet B (UVB) output at multiple reference points and found UVB always to be present, but at lower-than-expected levels. The highest irradiance was always at the umbilicus and the lowest was on the face. We evaluated compliance with accepted safety principles and federal guidelines and regulations; too often we found no eye protection and sometimes we found inadequate limits of exposure time. Persons with skin types I and II were sometimes promised a safe, effective UVA tan that would protect against sunburn. From our experience we concluded that if the industry is to continue, there is need for closer supervision and regulation.

Equipment and Supplies↗
PubMed1988

Isolation, via activity-directed fractionation, of mercaptobenzothiazole and dibenzothiazyl disulfide as 2 allergens responsible for tennis shoe dermatitis.

Although contact dermatitis from shoes is common, the causative allergen is frequently not known. Reliance cannot be placed on standard screening trays because such testing can be negative when testing to shoe materials is positive. Furthermore, the relevance of positive screening tests is almost never proven by extracting that allergen from the patient's shoes. We present a case of insole dermatitis to tennis shoes in which we directly isolated the causative allergens by step-by-step patch-test monitoring of active fractions. Chromatographic separation of the active fractions led to the isolation of 2 allergens, mercaptobenzothiazole (Captax) (MBT) and its dimer, dibenzothiazyl disulfide (Altax) (DBTD). Patch tests to DBTD were noticeably more potent than those to MBT. In what might be considered an obvious case of contact sensitivity to MBT, the actual allergen is DBTD. Using this method, unknown shoe allergens can be isolated, identified, and added to the shoe test tray of potential allergens.

Benzothiazoles↗