PubMed Health⌕ Search

Biomedical subjects

B Shroot

Publications and source records attributed to B Shroot.

At least 91 records · Page 5Linked to original sources
PubMed1985

Differentiation of keratinocytes in vitro: a new culture vessel mimicking the in vivo situation.

A culture vessel consisting of two independent chambers separated only by the growth substrate is described. Cells may be cultured on both sides of the growth substrate. Culture medium and gas exposure can independently be controlled in both compartments. Human hair follicles have been used as source of keratinocytes and the bovine eye lens capsule has been explored as growth substrate. The presence of 5% CO2 in air in the lower compartment appears to have a significant effect on the morphology of the cultures. When the cultures are being exposed to air with 5% CO2, the culture medium being applied in the lower compartment, formation of corneocytes characteristic for adult stratum corneum is induced, as evidenced by light and electron microscopy. To the knowledge of the authors, this stage of differentiation in vitro has not been obtained with previously described systems. Differentiation of the lower cell layers has been characterised with specific antibodies. The possible use of the system for applied and pure scientific research is discussed.

Animals↗
PubMed1985

Lipoxygenase products of arachidonic acid in human inflamed skin.

Monohydroxy acids (HETEs) and leukotriene B4 (LTB4) metabolites of arachidonic acid were measured in skin of healthy volunteers after ultraviolet B irradiation, and in the uninvolved skin of psoriatics after topical dithranol application. Exudate was collected from suction bullae on control and inflamed abdominal skin, and analysed for 12-HETE and PGE2 by GC-MS and LTB4 by bioassay. 12-HETE and PGE2 were raised at 24 h but not at 72 h after u.v.B irradiation: control and 24 h values were 13.7 and 41.5 ng ml-1 (P less than 0.05, n = 6) for 12-HETE respectively, and 4.5 and 30.2 ng ml-1 (P less than 0.01, n = 6) for PGE2. Dithranol application raised PGE2 levels from 23.1 ng ml-1 in control exudate to 62 ng ml-1 (P less than 0.01, n = 6) at 24 h before declining to base levels at 72 h. However, 12-HETE was raised at 72 h (200 ng ml-1, P less than 0.01, n = 5) but not at 24 h (104 ng ml-1) compared to control levels (50 ng ml-1, n = 5). The levels of the LTB4 were low (less than 100 pg ml-1), and no significant increases were observed. Arachidonic acid in inflamed skin can be metabolised by the cyclo-oxygenase and lipoxygenase pathway. It is probable that the lipoxygenase product 12-HETE is involved in these inflammatory reactions.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
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↗
PubMed1984

Determination of partition coefficients of glucocorticosteroids by high-performance liquid chromatography.

Two high-performance liquid chromatographic (HPLC) techniques have been used for the determination of the lipophilicity of 50 glucocorticosteroids. For a log P range of 1 to 3, we used a persilylated octadecylsilane phase saturated with 1-octanol, which was eluted with 1-octanol saturated phosphate buffer (pH = 7). For log P values greater than or equal to 3.00, the same phase was used without 1-octanol saturation and was eluted with different methanol-buffer mixtures. These two procedures allowed the determination of log P values ranging from 1.00 to greater than 5.00. Good agreement was found between these procedures and others described in the literature. The effect of different structural changes in the glucocorticosteroid molecule on the lipophilicity is discussed.

Chemical Phenomena↗
PubMed1984

Psoriatic hair follicle cells. I. Biochemistry and behavior in culture.

It is generally accepted that in psoriasis there is an alteration of epidermal cell proliferation. It has been reported that an increased rate of thymidine incorporation into keratinocytes is found in the upper part of the hair follicle in involved skin, but this is not the case in the lower part. Here we show that cells from psoriatic hair follicles could be brought in culture under the same conditions as those of normal hair follicles. Cells, whether originating from the upper or lower part of the hair follicle sheath either from involved or uninvolved psoriatic skin, show a faster rate of outgrowth in the first days of culture. Moreover, a large number of psoriatic cells have an increased motility in the early stages of culture, as compared to control cells. These properties can no longer be observed after several days in culture. The activity of glucose-6-phosphate dehydrogenase known to be increased in psoriatic plaques is normal in hair follicles isolated from these plaques. Protein gel electrophoretic investigations showed that there is no difference in gel patterns between normal and psoriatic hair follicles. In conclusion, the isolation of human hair follicles represents a simple method that allows psoriatic keratinocytes to be brought in culture and permits the study of certain aspects of the disease.

Cell Movement↗
PubMed1984

Psoriatic hair follicle cells in culture.

Psoriatic human hair follicle keratinocytes can be brought to culture under the same conditions as normal control hair follicle keratinocytes. In comparison with control cultures derived from non-psoriatics there are significant differences. However, no significant differences are found between cultures derived from either psoriatic involved or uninvolved skin. Some characteristics of psoriatic lesions are also encountered in the cultures. However, in contrast to the situation in a psoriatic lesion, cultures of psoriatic keratinocytes differentiate to a higher extent than comparable control cultures. A psoriatic morphology is therefore not completely formed. Whether this is due to the absence of a psoriatic dermis or to the fact that differentiation in culture is incomplete remains to be investigated.

Cell Differentiation↗
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↗
PubMed1982

Anthralin: chemical instability and glucose-6-phosphate dehydrogenase inhibition.

The chemical stability of the antipsoriatic drug, anthralin (1,8-dihydroxy-9-anthrone), in solution has been studied using high-performance liquid chromatographic analysis. The time course for decomposition in solution has been correlated with that of the inhibition of glucose-6-phosphate dehydrogenase, one of the most widely documented biochemical properties associated with anthralin. Solutions of anthralin in aqueous buffer (37 degrees, pH 7.5, under light protection) completely within 4 hr giving the 10,10'-dimer (40%), no detectable 1,8-dihydroxy-9,10-anthraquinone, and a greatly increased potency of inhibition of glucose-6-phosphate dehydrogenase. This increased inhibitory potency could not be explained by formation of the dimer which, like anthralin and its quinone, were shown to be only weak inhibitors of the enzyme. In acetone solution exposed to light and air, anthralin decomposed completely within 4 days, in part via the dimer as intermediate. The final solution had the characteristic color of anthralin-brown, contained the quinone (20%), and like decomposed aqueous solutions of anthralin, completely inhibited glucose-6-phosphate dehydrogenase. The results show that neither anthralin, nor either of its two identified decomposition products, is the potent toxic species against glucose-6-phosphate dehydrogenase.

Acetone↗
PubMed1982

On the interaction between anthralin and DNA: a revision.

The interaction between anthralin and DNA in vitro was examined. According to our data, there is no evidence for a specific interaction between these substances. However, we found that the addition of small quantities of DNA or albumin significantly enhanced the stability of aqueous solutions of anthralin and markedly affected the rate of anthralin decomposition.

Animals↗
PubMed1981

High-pressure liquid chromatographic determination of anthralin in ointments.

Anthralin concentration was determined in different ointments by high-pressure liquid chromatography, and results were compared with those of the USP assay technique. Significant differences existed between the claimed and the actual levels of anthralin in some preparations. Varying quantities of anthralin breakdown products were found, and their concentrations appear to be related to the nature of the formulation.

Anthracenes↗