Biomedical subjects

B Shroot

Publications and source records attributed to B Shroot.

58 records · Page 4Linked to original sources

PubMed1985

Psoriatic hair-follicle cells. II. Morphological differentiation of outer root-sheath cells in culture.

Psoriatic human hair-follicle keratinocytes were cultured and then examined using light and electron microscopy. In comparison to control cultures derived from non-psoriatics, there were significant differences: stratification in general was more extensive; suprabasal cells were flat instead of round; there were almost no depositions of basal lamina or of cellular debris on the growth substrate; numerous membrane coating granules and a few keratohyalin granules were present earlier in psoriatic cultures than in control cultures; and the differentiation pattern resulted in an earlier appearance of corneocyte-like cells, and clusters of these corneocyte-like cells appeared to have been shed into the culture medium. As in control cultures, no distinct stratum corneum was found. Whether these differences between psoriatic cultures and control cultures reveal an aberrant differentiation pattern for psoriatic cells in vitro is as yet unknown: due to the faster outgrowth in psoriatic cultures, a multilayered and therefore further-differentiated structure near the hair follicle could be obtained more rapidly in psoriatic than in normal skin.

Adult↗

PubMed1985

The in vivo fate of topically applied dithranol in the skin of the hairless rat. A comparison of continuous and short contact application.

The fate in vivo of topically applied 1,8-dihydroxy-9-anthrone (dithranol, anthralin) was investigated in the skin of the hairless rat, using a specially designed drug delivery system (film). The film was applied on intact skin as well as on skin with an impaired barrier function (stripped skin). The distribution of the drug was examined either after continuous application or at selected times after short contact periods. The exposed skin was extracted with diisopropylether and free dithranol, its dimer and quinone assayed by quantitative HPLC analysis. The incorporation of trace amounts of 3H-dithranol and 14C-dithranol in the vehicle made it possible to quantify the fraction of penetrated drug which was insoluble in ether. With continuous application to intact skin (up to 24 h), extractable dithranol rapidly reached a plateau level (15 min) and was concentrated in the stratum corneum. Substantial dimer formation occurred in both normal and stripped skin. Ether insoluble material rapidly predominated over soluble material, especially when the stratum corneum was absent. However, on short contact application (0.5-1 h), ether soluble material (dithranol in the stratum corneum) was quantitatively predominant in the intact skin. Removal of the vehicle after a short contact time resulted in the disappearance of dithranol from the skin (normal and stripped). In intact skin, the drug was converted into ether insoluble material. In the stripped skin, this insoluble fraction remained constant over the duration of the experiment (24 h).

Administration, Topical↗

PubMed1983

Characterization of the beta-adrenergic receptors of cultured human epidermal keratinocytes.

The presence of beta-adrenergic receptors has been demonstrated in membrane preparations from passaged human epidermal keratinocytes. The receptors were characterized in terms of density and binding properties. Using the titrated beta-adrenergic antagonists dihydroalprenolol and propranolol, the equilibrium dissociation constant (Kd) was found to be about 1.4 nM for the two antagonists with a receptor density of approximately 280 fmol/mg membrane protein. Stereospecificity of the binding sites was shown by the much lowered affinity to D-isoproterenol as compared to that of L-isoproterenol. By the use of subtype specific antagonists, the receptors were classified as beta 2 adrenoceptors. This finding is supported by the relative order of affinities of the agonists isoproterenol greater than epinephrine greater than norepinephrine. The Kd value for dihydroalprenolol was approximately the same when determined from equilibrium binding studies or from association and dissociation kinetics, suggesting that the ligand binding is a single step bi-molecular reaction.

Binding, Competitive↗

PubMed1983

Relative potencies of several non-steroidal anti-inflammatory drugs against soya bean 15-lipoxygenase.

The 15-lipoxygenase from soya bean has been claimed to represent a rapid assay procedure for drugs and chemical agents that inhibit other lipoxygenase products (Kingston, 1981). Although the exact role of products derived from skin lipoxygenase enzymes is not well established, many of these products, e.g. leukotriene B4, have inflammatory characteristics that warrant further examination (Camp, 1982). We have therefore started to evaluate anti-inflammatory drugs in vitro for their ability to inhibit soya bean 15-lipoxygenase, before appraising their effects in vivo in animal and human skin.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗