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Biomedical subjects

C N Burkhart

Publications and source records attributed to C N Burkhart.

At least 19 recordsLinked to original sources
PubMed2001

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.

Carbon↗
PubMed2001

Recommendation to standardize pediculicidal and ovicidal testing for head lice (Anoplura: Pediculidae).

Pediculosis capitis is a prevalent and highly communicable condition infesting millions of elementary school students annually. Topical insecticides are the present standard treatment for this condition. Because resistance of head lice to insecticides is a growing concern, assessment of efficacy of pediculicidal and ovicidal activity of the various agents is needed for public health interests. Given the number of anecdotal and market-driven reported studies, assessment of topical lice therapies requires standardized testing. Evaluations based on adaptations of World Health Organization guidelines are not ideal, whereas a protocol reflecting clinical exposure to insecticides is preferable.

Animals↗
PubMed2000

In pursuit of ceruminolytic agents: a study of earwax composition.

OBJECTIVE: To assess the protein and simple sugar content of earwax in pursuit of better ceruminolytic agents. STUDY DESIGN: Collected earwax specimens were tested in several media for dissolution before being analyzed for amino acid and carbohydrate content. PATIENTS: The samples were obtained from eight random patients requiring ear plug removal. RESULTS: The amino acid composition differs considerably from hair and stratum corneum of glabrous skin. Sugar analysis revealed high levels of galactosamine and galactose. CONCLUSIONS: This analysis of proteins and carbohydrates further characterizes earwax. Future ceruminolytic agents must dissolve lipid, keratin, and a monolayer of lipid covalently bound to the epidermal cells, which encourages cellular aggregation.

Amino Acids↗
PubMed2000

Scanning electron microscopic examination of the egg of the pubic louse (Anoplura: Pthirus pubis).

OBJECTIVE: The purpose of the study was to examine the eggs of pubic lice with consideration of their clinical relevance. STUDY DESIGN: Pubic lice eggs were examined by scanning electron microscopy (SEM). RESULTS: The egg is totally encased by a proteinaceous sheath, except for the operculum, by which oxygen exchange occurs. CONCLUSION: Pubic lice have proved resilient to human therapies through the ages. The anatomical target of topical insecticides for ovicidal kill is the operculum and the protective layers that surround the developing embryo. More research into these structures is warranted.

Animals↗
PubMed2000

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 sebosuppression) will need to be assessed to weigh the benefits of these second-generation acne-fighting peroxides.

Acne Vulgaris↗
PubMed2000

Clinical evidence of lice resistance to over-the-counter products.

BACKGROUND: Over-the-counter insecticidal solutions continue to be the mainstream treatment for most cases of head lice. Recorded insecticidal activity 15 years ago was at 100%, with ovicidal kill at 80%. Recently scattered accounts of possible resistance have surfaced. OBJECTIVE: This article is to document the general consensus that head lice are becoming resistant to standard over-the-counter therapies. METHODS: Direct testing of lethality of adult lice with permethrin and pyrethroid was assessed. RESULTS: Present over-the-counter products proved to be successful in only 9 of 32 head lice tested (28% insecticidal activity). CONCLUSIONS: Our series of cases further documents that over-the-counter head lice preparations no longer achieve high levels of insecticidal activity, suggesting increased resistance to these insecticides.

Animals↗
PubMed2000

Ivermectin: an assessment of its pharmacology, microbiology and safety.

Ivermectin (IVM) is the drug of choice for a variety of parasitic diseases due to its broad spectrum of activity and wide margin of safety. More than 18 million people are treated with IVM each year. Delivery modes include oral, topical, and s.c. injections. Its anti-parasitic activity depends upon species and developmental stages. Although IVM is believed to act mainly through interactions with invertebrate glutamate-gated chloride (GluCl) channel, other targets such as spleen cells and aminobutyric acid receptors may play important roles in the anti-parasitic activity of IVM. As several organisms have evolved resistance to IVM through mutations in p-glycoproteins and/or the GluCl channel itself, research continues on improvement of IVM either through mode of administration or the feasibility of alternative macrolides. An understanding of IVM's pharmacology is essential before improved therapeutics are created.

Administration, Oral↗
PubMed2000

An epidemiologic and therapeutic reassessment of scabies.

Scabies is a highly contagious infestation that causes considerable discomfort. Newer information concerning therapeutics and epidemiologic dogma needs assessment. An epidemiologic evaluation of available world data is analyzed, as well as an assessment of therapeutic alternatives. Using epidemiologic techniques, the following points are proven: scabies is not primarily a sexually transmitted disease; 30-year cycles of scabies do not exist; scabies spreads in households and neighborhoods in which there is a high frequency of intimate personal contact or sharing of inanimate objects; and fomite transmission is a major factor in household and nosocomial passage of scabies. Epidemiologic evaluation proves the necessity of fomite precautions and of treatment of asymptomatic family members and physical contacts of all cases of scabies. Single oral-dose therapy of ivermectin (Stromectol) appears to be the treatment panacea for this infestation.

Animals↗