Craig N. Burkhart

Acne: a review of immunologic and microbiologic factors

Acne vulgaris is a self-limiting skin disorder seen primarily in adolescents, whose aetiology appears to be multifactorial. The four main aetiological factors are hypercornification of the pilosebaceous duct, increased sebum production, colonization withPropionibacterium acnes, and subsequently the production of inflammation. Considerable investigation has addressed the immunologic reaction to extracellular products produced by the acne-causing organism, P acnes. The immunologic response involves both humoral and cell-mediated pathways. Further research should clarify the role of complement, cytotoxins, and neutrophils in this acne-forming response.

An assessment of topical and oral prescription and over-the-counter treatments for head lice

A plethora of head lice cases that require optimal therapeutic assessments are developing in elementary schools. Over-the-counter therapies continue to be the mainstream solution for most cases of pediculosis capitis, but the onset of resistant cases dictates a review of available treatment modalities. The increased efficacy of prescription drugs, namely topical 5% permethrin and oral ivermectin, underline the expanding role that physicians will serve in the eradication of head lice in our communities.

Synergistic Activity of Benzoyl Peroxide and Erythromycin

Background: Benzoyl peroxide (BP) is the most widely used topical agent for acne since its introduction in the 1960s. Concomitant topical treatment of BP and erythromycin is stated to be superior to BP alone. However, no synergistic activity has been found with this combination. Instead, such combination therapies are hypothesized to gain their efficacy by the coupled action of two effective treatments. The antibiotic kills all susceptible bacteria and the BP eliminates the resistant strains. Objective: The purpose was to compare radical production by BP alone and with various antibiotics to determine whether certain antibiotics increase radical formation by BP, as the antibacterial activity of BP may correlate with the amount of radicals it forms. Methods: Polymerization of tetraethylene glycol dimethacrylate was used as a test of BP radical activity. Results: The results suggest that radical activity increases upon addition of certain antibiotics, such as erythromycin, to a solution of BP. Conclusion: Radical activity of BP in tetraethylene glycol dimethacrylate is increased when tested in consort with several antibiotics, such as the macrolides. We propose that the tertiary amines contained on certain antibiotics are responsible for catalysis of BP radical formation. If increased radical formation correlates with enhanced biological effect, then these data reveal the possibility of a biological synergism in mixtures of BP and antibiotics. An understanding of the mechanism of catalysis of BP radical formation by antibiotics may lead to the discovery of improved treatments for acne.

Molecular composition of the louse sheath.

Flash pyrolysis-gas chromatography/mass spectrometry was used to assess the chemical composition of the head louses nit sheath. The pyrolyzate of the female insects secretions, which form a cement-like cylinder holding the egg onto the hair, is dominated by amino acid derivatives and fatty acids. No chitin-specific compounds were detected in the sheath. These results, contrary to previous reports, show that the polymeric complex of the sheath is composed of proteinaceous moieties, possibly cross-linked to aliphatic components. This study constitutes the first chemical characterization of the pyrolysis products of insect (louse) glue and unequivocally confirms that louse sheaths are not chitinous, as suggested by earlier histochemical studies. Development of agents that might loosen nits from the hair shaft is dependent on research that addresses the chemical composition of the nit sheath.

Cerumen composition by flash pyrolysis-gas chromatography/mass spectrometry.

Objective To assess the chemical composition of cerumen by flash pyrolysis-gas chromatography/mass spectrometry. Study Design Collected earwax specimens were fractionated into residue and supernatant by means of deoxycholate. This natural bile acid produces significantly better disintegration of earwax in vitro than do presently available ceruminolytic preparations, and also has demonstrated excellent clinical results in vivo to date. Patients The sample for analysis was obtained from a patient with clinical earwax impaction. Results The supernatant is composed of simple aromatic hydrocarbons, C5-C17 straight-chain hydrocarbons, a complex mixture of compounds tentatively identified as diterpenoids, and steroids, in particular cholesterol. The residue, on the other hand, produced simple aromatic compounds (including benzenes, phenols, and benzonitriles), C5-C25 straight-chain hydrocarbons, greater relative quantities of nitrogen compounds and phenol, and lesser importance of the (tentatively identified) diterpenoids. Conclusions Through the use of the detergent deoxycholate, squalene and a tentatively identified diterpenoid were revealed to be present in a free, unbound state, whereas some steroids and hydrocarbons appeared to be bound to a macromolecular structure by nitrogen linkages or other bonds. Additionally, this study reintroduces detergents as a viable method of earwax removal, specifically the bile acids.

OUR SCABIES TREATMENT IS ARCHAIC, BUT IVERMECTIN HAS ARRIVED

The Correspondence Section serves as a forum for opinion exchange about subjects of general interest such as dermatologic training, relations between dermatologists and pharmaceutical houses, governmental control of dermatology and medical practice in general, peculiarities of dermatology related to geographic, climatic, or racial factors, the flow of information and publications, as well as other concerns the readership might have. Contributions are welcome and should conform to the usual format for correspondence. Manuscripts will undergo standard editorial procedures. Submit all correspondence to PO Box 020010, Miami, FL 33102.

Effects of benzoyl peroxide on lipogenesis in sebaceous glands using an animal model.

Background: Benzoyl peroxide is the most widely used topical agent for acne since the 1960s. Concomitant treatment of benzoyl peroxide with oral, or topical antibiotics diminishes the multiplication of antibiotic-resistant strains of Propionibacteria acnes. Besides being antibacterial, the chemical also functions as a peeling agent, has comedolytic activity, reduces free fatty acid levels, and is touted to be sebosuppressive. Objective: The purpose was to determine the ability of topically applied benzoyl peroxide to suppress lipogenesis of the sebaceous glands. Methods: The data were obtained employing an animal model for human sebaceous glands, namely, the flank organs of female golden Syrian hamsters. Results: Our results reveal no inhibition of lipogenesis in sebaceous glands by topical application of benzoyl peroxide. Conclusion: Despite many functions beneficial in acne therapy, benzoyl peroxide does not possess sebosuppressive capabilities. With the advent of water-soluble organic peroxides revealing similar antimicrobial activity to benzoyl peroxide, all therapeutic parameters (save for sebosup-pression) will need to be assessed to weigh the benefits of these second-generation acne-fighting peroxides.

Head Lice Therapy Revisited

To the editor: We would like to second the comments of Bainbridge, Klein, et al,l in their recent article in Clinical Pediatrics, that finetoothed combing of nits and adult lice out of the scalp hair is of paramount importance in treatment of head lice. Although our laboratory is vigorously testing various compounds for clinical effectiveness in nit removal,2 fine-toothed combing of dripping hair after shampooing with conditioners is the best known method for nit removal. The hair should be wet, for this decreases the mobility of the adult lice. In fact, some advocate lengthy sessions of combing by itself as a therapy for head lice.3 A refinement of the nit comb, named the LiceMeister, is available through the National Pediculosis Association. Other nonpesticidal therapies for pediculosis capitis include petrolatum, mayonnaise, pomades (such as Proclaim Conditioning Hair Dress, and Soft Sheen Sporting Wave), and Hair Clear 1-2-3 by Quantum Corporation.4 We would like to clarify that the 100% success rate reported by Bainbridge, Klein, et all with permethrin and pyrethrin is a reflection of the rigorous fine-toothed combing performed by the authors and does not properly reflect insecticidal treatment by itself. A more realistic assessment was reported by Khudobin,5 who treated 1,657 infested school children with 81% cure with one treatment with permethrin. Permethrin, unlike pyrethrin, is detectable on the hair for 14 days and maintains pesticidal capabilities if not coated over by cream rinses or conditioning shampoo. Inasmuch as none of the available topical insecticides are 100% ovicidal, and the developing eggs have no central nervous system for the first 4 days of existence for topical pesticides to attack, patients should be instructed to