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Biomedical subjects

S M Puhvel

Publications and source records attributed to S M Puhvel.

33 records · Page 2Linked to original sources
PubMed1977

A reevaluation of fatty acids as inflammatory agents in acne.

The currently widely held theory that intrafollicular free fatty acids (FA) are the primary agents instigating inflammatory changes in acne is based on circumstantial evidence. There is no direct evidence that FA in physiologic concentrations are inflammatory. In the present study the quantities of FA present in isolated pilosebaceous ducts and in isolated comedones were analyzed. Using these values, the effect of FA on intracutaneous injection into human skin was investigated. The range of FA in 257 isolated pilosebaceous ducts from skin of the upper back of 10 male subjects was 0.19 to 2.43 mug, with an average of 0.89 +/- 0.75 mug of FA per duct. The mean FA content in 45 open comedones was 63.6 +/- 24.8 mug per comedone. Fatty acids for intracutaneous testing were isolated from human skin surface lipids and from hydrolyzed triglycerides purified from pooled isolated sebaceous glands. Twenty-six subjects received 100 mug of FA intracutaneously in the upper back. The response to FA injections could not be distinguished from the response to saline control injections. By 24 hr no erythema, induration, or any visible marks of inflammation were present in the skin of any of the subjects tested. At the histologic level a mild inflammatory infiltrate consisting perdominantly of lymphocytes was slightly more marked in the FA injection site than in the saline control injection site. Increasing the amount of FA injected to 500 mug still produced no visible inflammatory response in human skin. We conclude that intracutaneous injections of FA in physiologic concentrations do not produce more than a very mild inflammatory reaction in human skin and suggest that the role of Propionibacterium acnes in the pathogeneisis of acne may be more complex than merely as a source of intrafollicular lipases.

Acne Vulgaris↗
PubMed1977

Lymphocyte transformation in subjects with nodulo cystic acne.

Patients with severe nodulo-cystic acne are known to have elevated serum antibody levels and increased immediate hypersensitivity reactions to Propionibacterium acnes. This organism is the predominant bacterium in normal pilosebaceous follicles of human skin, and can be consistently isolated from pustular lesions in acne. Previously it had been observed that delayed cutaneous hypersensitivity reactions to P. acnes were negative in patients with acne. The present study investigated the proliferative response of lymphocytes from patients with nodulo-cystic acne to phytohaemagglutinin (PHA) and P. acnes antigen stimulation. The response to PHA stimulation was within normal limits. The response to P. acnes antigen showed a significant increase over control values obtained by testing lymphocytes from acne-free subjects. Thus cell mediated immunity to P. acnes may be present in subjects with severe inflammatory acne. These findings raise the possibility that reactions to P. acnes may contribute to intensifying the inflammatory response in acne lesions.

Acne Vulgaris↗
PubMed1976

Acne from an immunological perspective.

Patients with acne vulgaris, particularly those with severe inflammatory forms of the disease, are known to have high titers of serum antibodies, and intensified immediate hypersensitivity reactions to P. acnes antigens. The significance of this fact has not been clarified, but it is possible that antigen-antibody reactions involving P. acnes in the perifollicular dermis could intensify the inflammatory response in certain forms of acne. Further studies utilizing newer, more sophisticated techniques are needed to identify the role of P. acnes antigens in affecting such fundamental phenomena as chemotaxis, cell-mediated immunity, activation of the complement cascade and reticuloendothelial system stimulation. Answers to these basic questions have the pathogenesis of that common but even more complex disease, acne.

Acne Vulgaris↗
PubMed1975

Esterification of (4--14C)cholesterol by cutaneous bacteria (Staphylococcus epidermidis, Propionibacterium acnes, and Propionibacterium granulosum).

Cholesterol and cholesteryl esters constitute 3 to 5% of the lipids derived from human sebaceous glands. The present study demonstrates that cutaneous bacteria, Staphylococcus epidermidis, and to a lesser extent Propionibacterium acnes, and Propionibacterium granulosum, esterify [4--14C]cholesterol to steryl esters in vitro. The degree of esterification is a characteristic of the strain of organism, ranging from 0 to 32.7% in the organisms tested. Cholesterol esterification in these experiments was dependent on the addition of homogenates of isolated, pooled sebaceous glands to the incubation medium. Indirect evidence suggests that the fatty acids from sebaceous triglycerides are utilized for cholesterol esterification by the bacteria. These results indicate that the proportion of steryl esters in skin surface lipids may be influenced by the density of the microbial population in the skin.

Carbon Radioisotopes↗
PubMed1975

Analysis of lipid composition of isolated human sebaceous gland homogenates after incubation with cutaneous bacteria. Thin-layer chromatography.

The effects of specific species of skin bacteria on human sebaceous gland lipids in vitro were analyzed. Isolated dissected sebaceous glands were pooled, homogenized, and sterilized, then incorporated into peptone-yeast extract medium and used as substrate for growth of Propionibacterium acnes, P. granulosum, and Staphylococcus epidermidis subgroup II. The sebaceous lipids were analyzed by thin-layer chromatography before and after bacterial growth. The most striking effect of bacteria on sebaceous gland lipid composition was the hydrolysis of sebaceous triglycerides. The degree of hydrolysis varied with bacterial strain but was most complete with P. acnes and P. granulosum. Staphylococci were not effective in hydrolyzing sebaceous triglycerides at pH 4.5 although, when the pH of the medium was raised to pH 6.4, some strains of staphylococci were as effective as the propionibacteria in hydrolyzing sebaceous triglycerides to free fatty acids. Thus minor changes in acidity may play asignificant role in controlling the lipolytic activity of staphylococci on skin. Another effect of bacterial action on sebaceous gland lipids was the esterification of sebaceous cholesterol to cholesteryl esters. Thus, bacterial action must be taken into account in evaluating studies of alterations in cutaneous cholesterol and cholesteryl esters in skin surface lipids in normal and disease states.

Bacteriological Techniques↗
PubMed1975

Quantification of bacteria in isolated pilosebaceous follicles in normal skin.

A technique for quantitating bacteria in isolated pilosebaceous follicles is described. This involves microdissection of the follicles from biopsies of skin, using the method of chemical pretreatment of skin to facilitate the separation of the epidermis and epidermal appendages from the dermis. The aerobic cocci and anaerobic diphtheroids in pilosebaceous follicles in 66 biopsies of scalp and 48 biopsies of skin of the upper back were quantitated using this technique. On the back, aerobic staphylococci were very sparse in normal follicles, indicating that their primary habitat on the skin must be on the skin surface rather than within follicles. Of 138 isolated follicles from skin of the upper back, 94 contained no aerobic cocci. Anaerobic organisms were present in high numbers within normal follicles. The geometric mean density of anaerobes in 138 isolated follicles from skin of the upper back was 3.8 X 10(4) diphtheroids per follicle. Eighty-eight follicles contained more than 10(4) anaerobic diphtheroids. Using data from scalp biopsies we found that there was a correlation between the weight of sebaceous glands and the density of anaerobes within the follicles attached to these glands (coefficient of correlation = 0.6).

Acne Vulgaris↗
PubMed1965

Levels of antibody to Staphylococcus epidermidis in patients with acne vulgaris.

Sera from 23 patients with acne vulgaris of varying degrees and sera from 15 patients with skin diseases other than acne were tested for antibody levels to Staphylococcus epidermidis by use of bacterial agglutination and agar-gel immunodiffusion. Antibody levels to S epidermidis varied from 0 to 1:160 in both the patients with acne and in the control groups. There was no correlation between the antibody level to S epidermidis and the degree of acne. In a previous investigation it was found that antibody levels to Corynebacterium acnes are significantly increased in serum from patients with papulopustular and cystic acne. Both S epidermidis and C acnes can frequently be isolated from lesions in acne. The fact that antibody levels are increased to C acnes but not to S epidermidis may indicate that the mere presence of an organism in the acne lesion is not sufficient stimulation for antibody formation. The increase of antibody to C acnes which was demonstrated previously in patients with severe acne vulgaris may therefore reflect a direct involvement of the organism in the acne process.

Acne Vulgaris↗