Effects of mold proteases on the biological activity of allergenic pollen extracts.

OBJECTIVE: To determine the effect of mold extracts with high protease activity on the biological activity of allergenic tree, grass, and weed extracts, using in vivo and in vitro methods, in atopic dogs. ANIMALS: 15 dogs with history and clinical signs of atopy. All dogs had strong positive reactions (3+ or 4+) to 1 or more preselected allergens and negative reactions (O) to molds. PROCEDURE: Mold extracts and saline solution were coincubated separately with tree, grass, and weed pollen extracts at 4 C for 30 and 80 days. Skin end-point titration (30-day incubation) and ELISA inhibition (30- and 180-day incubations) tests were performed on all samples. The biological activity of pollen extracts coincubated with mold extracts was compared with that of pollen extracts coincubated with saline solution. RESULTS: In the skin end-point titration test, weed pollen extracts coincubated with a mixed mold extract lost a statistically significant amount of biological activity, compared with saline coincubated controls. In the ELISA inhibition test, grass and weed pollen extracts incubated with a mixed mold extract lost a significant amount of biological activity, compared with saline coincubated controls. A significant correlation in the measurement of biological activity was found between a loss of end-point dilution in the skin end-point titration test and a decrease in relative potency, as measured by the ELISA inhibition test for allergenic grass and weed extracts. CONCLUSION AND CLINICAL RELEVANCE: Mold proteases can decrease the biological activity of certain grass and weed pollen extracts when coincubated in the same vial for 30 days. Separation of mold and pollen extracts, when preparing immunotherapy vaccines, may help prevent loss of pollen extract potency and increase the vaccine's stability and efficacy.

The Mexican hairless dog as a model for assessing the comedolytic and morphogenic activity of retinoids.

The skin of the Mexican hairless dog is covered with comedones, and this animal therefore provides a potentially useful model to assess the comedolytic activity of topical anti-acne drugs. We treated an animal with three different formulations of tretinoin for a 14-week period, and all produced a similar clinical response. There was a striking reduction in the number of comedones, and the skin became lighter and more uniform in colour. Histological changes were similar to those reported in humans treated with tretinoin, but a novel finding was incomplete neogenesis of hair follicles. We suggest that the Mexican hairless dog may be a useful model for screening novel molecules for retinoid activity.

Zoonoses of dermatological interest.

The zoonoses are those diseases transmitted from animals to humans. Although commonly thought to be infectious in origin such as scabies or dermatophytosis, inflammatory processes may also be zoonotic. Contact dermatitis may result from allergens being carried from animals to humans. Although the scabies mite is somewhat species specific, various mites sometimes have the opportunity of producing skin disease on man (ie, canine scabies, porcine scabies, and feline scabies [notoedric mange]); cheyletiellosis is caused by a similar mite, often found in rabbits. The index case of superficial fungal infections may be the household pet, whereas the cause of flea bite dermatitis (papular urticaria) may be the lack of an animal, resulting in the flea choosing a human for feeding. Understanding zoonotic skin diseases will improve the clinician's diagnostic skills. Both the human and animal patient will then receive more effective treatment in a quicker fashion.

An evaluation of ivermectin in the treatment of sarcoptic mange in dogs.

A colony of mixed-breed dogs (n = 298) naturally infested with Sarcoptes scabiei was treated, twice, with 200 micrograms of ivermectin/kg of body weight subcutaneously at 14-day intervals. After the initial injection, positive skin scrapings from 20 treated dogs decreased from 7 to 1 and the degree of pruritus decreased. In contrast, positive skin scrapings from 22 nontreated dogs increased from 10 to 14, and there was an additional deterioration in the condition of the skin and an increase in the degree of pruritus. Complete control was noticed in all treated dogs by posttreatment day 28 (14 days after a 2nd injection) based on negative skin scrapings.

Immunologic studies of progeny of atopic dogs.

Atopic dogs were bred to establish a colony of progeny predisposed to develop type I hypersensitivity. In a 2-year period, 72 pups were born and were monitored for clinical evidence and immunologic "markers" of atopic disease. Thirteen dogs in the colony, belonging to the oldest age group, manifested clinical signs compatible with atopic disease. Immunologic variables relative to serum IgE levels, parasitic infection, and duration of severity of clinical signs of disease were studied in this group. Analysis of this data did not identify indicators which could be used to predict the development of the atopic state in dogs.

The atopic dog model: report of an attempt to establish a colony.

In an attempt to establish a colony of atopic dogs as a research resource, dogs with seasonal dermatitis - a reported manifestation of naturally occurring allergy in that species - were identified, acquired, and inbred. Progeny were studied during their first 2 years of life to determine if the trait could be genetically transmitted and to investigate the hypothesis that this spontaneously occurring dermatitis correlates with positive laboratory measurements for specific IgE to airborne allergens. (Serial immunoglobulin levels, including total IgE, end-point titration of histamine, and results of fecal examinations for identification of parasites were also investigated and are to be the subject of a separate publication.) Only a weak correlation between positive direct skin test results and the appearance of seasonal dermatitis was found in initial studies. Neither the results of testing by passive cutaneous anaphylaxis nor radioallergosorbent procedures correlated with positive clinical findings. Independently conducted clinical examinations and direct skin testing using selected antigens, as well as additional bronchial challenges of representative animals from the colony, also failed to furnish evidence of atopy in the dogs. Therefore, the goal of establishing an inbred line of atopic animals was not accomplished within the allotted 2-year period. Also, the data did not show a positive correlation between the seasonal dermatitis and measurements for specific IgE to airborne allergens.

Effects of hormonal therapy on the microbiology of seborrheic dogs.

Quantitative and qualitative bacterial assays were performed on the skin of three dogs with endocrine-related primary metabolic seborrhea. After the dogs were treated (thyroid supplementation or castration, bacterial analyses were again performed on the same sites. Before therapy, the dogs had a cutaneous flora composed mainly of Staphylococcus aureus coagulase-positive organisms. After therapy, there was a significantly lower bacterial count, and two of the dogs had floras consisting mainly of coagulase-negative cocci. During the study, the two dogs that reverted bacteriologically to a normal cutaneous microenvironment became normal dermatologically. The third dog improved, but continued to have minor signs of seborrhea.

Microbiology of normal and seborrheic canine skin.

Quantitative and qualitative bacterial assays were performed on the skin of 15 normal and 32 seborrheic dogs. Nonionic detergent scrubs were made on areas demarcated by glass sidearm cylinders. Quantitative analysis was accomplished by the serial dilution technique, and the bacteria were identified by individual and colonial morphology and by enzyme production. Areas measured on control dogs had a markedly lower total bacterial count than similar areas measured on seborrheic animals. Control dogs had a flora consisting primarily of coagulase-negative cocci, whereas seborrheic dogs usually had a cutaneous flora composed primarily of Stahylococcus aureus, coagulase-positive.

Dapsone for treatment of pruritic dermatitis (dermatitis herpetiformis and subcorneal pustular dermatosis) in dogs.

Pruritic dermatitis in 4 dogs was not responsive to treatment with corticosteroids and antibiotics. Histologic findings in 3 cases were suggestive of subcorneal pustular dermatosis, and those in the 4th case were compatible with dermatitis herpetiformis. All 4 dogs responded rapidly and completely to treatment with dapsone.

Subacute administration of Plak-Lite sodium fluorescein solution in hamsters.

The purpose of this research was to evaluate the potential toxic effects of Plak-Lite disclosing solution, which contains 0.75% sodium fluorescein U.S.P. in buffered glycerol in hamsters under defined and exaggerated conditions. In oral dosing experiments, volumes calculated at least 50, 200 or 1000 times the human daily use level were administered. For intraoral application the 1000 X human use level was selected. The control group was dosed orally with the 1000 X dose volume of water. All animals were treated once a day for 31 or 92 days. Daily examination of animals revealed no overt drug or dosing-related effects. Weights recorded at 31 or 92 days were similar for all groups. Histological evaluation performed on tongue, oral mucosa, cheek pouch, stomach (3 sections), liver, kidney, spleen, small intestine (3 sections), large intestine and bladder revealed no pathological changes. This study demonstrates the safety of Plak-Lite disclosing solution when administered at exaggerated dose levels via routes simulating human use.

Thin-layer chromatographic assays of histamine and its metabolites in urine of man and dog.

A method for the extraction and quantitation of histamine and its metabolites from relatively small volumes of urine is described. It employs primarily ion-exchange and thin-layer chromatography and allows for quantitation in the mug range. Studies of atopic man and dog that employed this procedure yielded values comparable to those reported with gas chromatographic methods.