Biomedical subjects
N L Sykes
Publications and source records attributed to N L Sykes.
Acne. A review of optimum treatment.
Acne vulgaris is a disease of the pilosebaceous unit of the skin. It may have profound psychological sequelae. The lesions are due to abnormally adherent keratinocytes causing plugging of the follicular duct followed by accumulation of sebum and keratinous debris. This results in the formation of the primary lesion of acne, the comedo. Inflammation of comedones produces papules, pustules and nodules, which often prompt patients to seek treatment. Various effective treatments include topical anti-inflammatory, antibiotic and peeling agents, oral antibiotics, topical and oral retinoids, and hormonal agonists and antagonists. Useful combination regimens are discussed, and treatment approaches suggested. Mild cases of comedonal acne may respond to a topical retinoid or benzoyl peroxide, while inflammatory lesions benefit from topical antibiotics. More severe inflammatory acne is treated with systemic antibiotics. Recalcitrant cases often require oral isotretinoin or hormonal manipulation.
Non-calcium environmental sensitivity of intracellular Indo-1.
Several mechanisms might account for the difference between spectra of Indo-1 measured on intracellular and on extracellular dye. Experiments to discriminate between various possibilities used quantitative analyses of intracellular and extracellular Indo-1 spectra. Intracellular calcium-free dye showed a 20-nm blue shift, when compared with the extracellular case. However, the calcium-bound spectrum was unaffected by the intracellular milieu. This eliminated the possibility that the spectral shift was due to calcium-independent unhydrolyzed dye. The spectral shift was reversible and was seen in resting cells as well as calcium-depleted cells. Since the apparent dissociation constant for calcium was not detectably different inside the cell, the possibility of competitive binding to another divalent cation, such as Zn2+, was eliminated as the principle source of the spectral shift. The shift appears to be due to a noncompetitive solvent effect on the emission of the calcium-free dye that is absent in the calcium-bound form.
Magnetic labeling and cell sorting.
Magnetic labeling by a magnetite-antibody conjugate has been combined with magnetic filtration (high gradient magnetic separation) to effect a rapid and efficient separation of a selected cell population from a suspension of single cells. Samples of more than 10(8) cells could be fractionated in about 5 min with complete recovery. The system has been applied to a model system using red blood cells (sheep or chicken) and commercial antibodies against species-determined cell surface antigens. Enrichments of labeled cells by factors of up to 37-fold were observed. The approach was relatively insensitive to details in the experimental protocol and to the number of unlabeled cells which were in the sample. Thus, the method was easy to use and can readily be scaled up to handle large samples containing 10(8) labeled cells in a total of 10(11) or more. It should be useful as a pre-enrichment scheme for suspensions in which cells of interest are rare and, consequently, very inefficiently sorted by fluorescence-activated instruments.