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Biomedical subjects

A J Vermorken

Publications and source records attributed to A J Vermorken.

At least 19 recordsLinked to original sources
PubMed1988

The suitability of saliva for detection of glucose-6-phosphate dehydrogenase deficiency.

Saliva was investigated for its suitability as a biopsy tissue for the determination of glucose-6-phosphate dehydrogenase deficiency. It appears that there is a significant difference between the activity of the enzyme in patients and controls. However, some controls have very low values making discrimination between patients and controls using a qualitative method impossible. Glucose-6-phosphate dehydrogenase deficiency is a relevant clinical problem in many rural areas in developing countries. Existing methods for determination of the deficiency in blood and hair follicles do not meet the criteria necessary for their large scale introduction in the areas of the world that are concerned by the problem. The present study shows that saliva is not a suitable alternative. Between the three biopsy tissues compared: blood, hair follicles and saliva, hair follicles remain most attractive since their isolation hardly involves the risk of infection. A simplified method for the detection of glucose-6-phosphate dehydrogenase activity in hair follicles that would allow health service workers in the field to determine the carrier status of pregnant women might form the basis for a future kernicterus prevention programme.

Glucosephosphate Dehydrogenase↗
PubMed1987

Determination of glycogen and enzymes of glycogen metabolism in human hair follicles.

The skin epithelium and its organelles use glycogen as well as glucose as source of energy. Therefore the characterisation of glycogen metabolism and the enzymes involved is important in the study of mechanisms regulating the normal or abnormal differentiation of skin organelles such as sebaceous glands and hair follicles. The present paper describes fluorimetric methods for the determination of glycogen and for the measurements of phosphorylase and phosphorylase kinase activity in one and the same lysate of minute tissue samples. The methods were tested for their suitability on freshly isolated human hair follicles and cultured hair follicle cells. The possible use of these techniques for studies on the pathophysiology of acne and hirsutism is discussed.

Cells, Cultured↗
PubMed1987

Is increased 5 alpha-reductase activity a primary phenomenon in androgen-dependent skin disorders?

Testosterone metabolism was investigated in fractions of human skin, enriched in epidermis, dermis, sebaceous glands, and sweat glands, by histologic sectioning of skin punch biopsies, and the results were compared with two culturable skin cells, i.e., keratinocytes and fibroblasts. Since sebocytes could not be brought in culture, metabolism was also investigated in the hamster flank model. In the epidermal tissue of the skin biopsies the predominant metabolite was androstenedione, formed by the enzyme 17 beta-hydroxysteroid dehydrogenase. The same was true for cultured hair follicle keratinocytes. In the deeper skin layers the formation of androstenedione was markedly reduced, whereas the formation of 5 alpha-reduced metabolites was highly increased, with a maximum in the skin fractions containing large sebaceous glands. Cultured shoulder skin fibroblasts showed a markedly different testosterone metabolism compared with the sectioned skin biopsies, suggesting that dermal fibroblasts play a less important role in the overall skin testosterone metabolism. The present approach, allowing the comparison of testosterone metabolism in different substructures of the same skin biopsy provides new evidence that the high 5 alpha-reductase activity in the specific skin fractions must be mainly ascribed to the sebaceous glands. These results render a previous hypothesis, stating that the elevated level of 5 alpha-reductase and subsequent formation of dihydrotestosterone in androgenetic alopecia and acne (usually accompanied by seborrhea) could therefore simply be the consequence of sebaceous gland enlargement, much stronger. This hypothesis is further evaluated by quantitative correlation of sebaceous gland size with enzyme activity in the hamster flank model.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1987

Psoriatic hair follicle cells. III. Characterization of aberrant morphology in differentiating cultures.

Psoriatic and control human hair follicle keratinocytes were cultured on bovine eye lens capsules in Epicult dishes for a period of 5-6 weeks and examined using light microscopy. The following morphological differences between cultures were observed: 1. The lower cell layers contained predominantly flattened cells in psoriatic cultures instead of roundish in control cultures. 2. The differentiation pattern was irregular in psoriatic cultures instead of regular in control cultures. 3. The differentiated zone of psoriatic cultures was more compact and thicker in comparison to normal cultures. These differences might allow discrimination between normal and psoriatic cultures.

Cells, Cultured↗
PubMed1987

Substrate specific sulfatase activity from hair follicles in recessive X-linked ichthyosis.

Recessive X-linked ichthyosis (RXLI) has its biochemical basis in a defect of the enzyme steroid sulfatase. Since several studies have reported a simultaneous deficiency of arylsulfatase C and steroid sulfatase it has been hypothesized that both enzymes are identical. In human hair follicles, however, hydrolytic activity for 4-methylumbelliferone sulfate, the substrate for arylsulfatase C, is found, while dehydroepiandrosterone sulfate is not hydrolyzed at all. These findings suggested the possible existence of two different enzymes. In the present paper structure-activity studies and molecular energy calculations are used for the demonstration that the remaining sulfatase activity in hair follicles of RXLI patients can be explained on the basis of the assumption that the enzyme has not lost its total function but has become less efficient.

Adolescent↗
PubMed1986

Studies on the local activity of antiandrogens at the molecular and histological level.

Androgen dependent skin disorders are important in clinical practice. Effective topical antiandrogens would lead to a breakthrough in their treatment. Although many attempts have been performed to develop such compounds, major successes have not been forthcoming. In the present study three existing antiandrogenic molecules have been compared with regard to their effect on androgen metabolism, receptor competition and on histological parameters in the hamster flank organ test. It appears that the effect on the hamster pigmented spot can be predicted on the basis of molecular mechanism. However, the effects on histological parameters are apparently dependent on additional factors such as metabolism of the active substance before reaching the sebaceous structure or limited penetration through the skin surface. The results indicate that in the development of new antiandrogens pre-screening can be performed with the aid of metabolic and receptor studies, while the histological parameters in the hamster flank organ test provide an animal model with a good predictive value.

Androgen Antagonists↗
PubMed1986

Actin distribution patterns in patients with adenomatosis of colon and rectum.

The actin cytoskeleton was examined in cultured skin fibroblasts of control individuals and patients with adenomatosis of colon and rectum using a fluorescent dye specific for F-actin, NBD-phallacidin. We confirmed that the actin distribution pattern differs significantly between the group of controls and the group of patients. However, the method is not practicable for the diagnosis of individual patients due to the number of false positives and negatives to be expected.

Actin Cytoskeleton↗
PubMed1986

Psoriatic hair follicle cells. IV. Calmodulin levels in freshly isolated and cultured human scalp hair follicle cells.

Calmodulin levels were measured by radioimmuno-assay in freshly isolated and cultured psoriatic human scalp hair follicle cells. The mean value +/- SEM for calmodulin was 1.97 +/- 0.15 ng calmodulin micrograms-1 protein for 16 control subjects whereas calmodulin levels were significantly increased in psoriatic hair follicles, 2.93 +/- 0.26 ng calmodulin micrograms-1 protein (uninvolved skin) for 18 patients and 3.09 +/- 0.21 ng calmodulin micrograms-1 protein for involved skin derived hair follicles for 17 of these patients. In vitro, 3-week-old cultures of psoriatic keratinocytes contained less DNA and more calmodulin per DNA than their normal counterparts. When 6 week-old cultures of psoriatic and control hair follicle keratinocytes were compared, this difference disappeared. These results are related to the state of differentiation of these cultures.

Calmodulin↗
PubMed1986

Glutathione-S-epoxide transferase in human hair follicles.

A fluorometric assay for determination of glutathione-S-epoxide transferase (GSH-T) activity in freshly isolated human hair follicles or cultured cells is described. With this assay, basal levels of the enzyme in hair follicles have been compared between smokers and non-smokers. No significant difference between both groups could be detected. GSH-T was not elevated after treatment of cultured hair follicle keratinocytes with benz[a]anthracene or clotrimazole. The same result was obtained with cultured skin fibroblasts from Ah-responsive and Ah-non-responsive mice. The possible significance of basal GSH-T levels for assessment of the risk of individuals for the carcinogenic action of polycyclic aromatic hydrocarbons is discussed.

Adult↗
PubMed1986

Phosphoglycerate kinase deficiency: biochemical studies on hair follicles.

A fluorimetric procedure for the determination of phosphoglycerate kinase in single human hair follicles is described. Enzyme studies on different parts of hair follicles after dissection show that the distribution of glucose-6-phosphate dehydrogenase matches that of phosphoglycerate kinase. Glucose-6-phosphate dehydrogenase can therefore be used as a reference enzyme to compensate for differences in hair follicle sizes. It was shown that the variation in the values found in individual hair follicles is improved by relating phosphoglycerate kinase to glucose-6-phosphate dehydrogenase activity. In areas of the world where glucose-6-phosphate dehydrogenase deficiency occurs frequently, an autosomally inherited reference enzyme may be preferred. It is shown that 6-phosphogluconate dehydrogenase is useful in this respect. Upon storage a gradual drop in the activity of all three enzymes was observed, but the rate of decrease was about equal: the enzyme activity ratio was, therefore, almost unaffected for a period of one week. This allows the determination of phosphoglycerate kinase even in mailed hair follicles.

Enzyme Stability↗
PubMed1985

Covalent binding of BP-metabolites to DNA of cultured human hair follicle keratinocytes.

Primary cultures of human hair follicle keratinocytes were established by using a basement membrane-like growth substrate, the bovine eye lens capsule. A method was adapted for the isolation of 3H-benzo(a)pyrene (BP)-modified DNA from the cellular outgrowth of only one hair follicle (approximately 2 X 10(5) cells). In a routine procedure hair follicle keratinocytes were incubated with 0.5 microM 3H-BP for 24 h. The purified DNA was subjected to enzymic hydrolysis and the adducts were analyzed by Sephadex LH-20 column chromatography followed by HPLC. Only one major adduct, which represented 60-80% of the total radioactivity which can be confined to modified nucleosides in the LH-20 chromatograph, could be identified. This adduct co-chromatographed with the marker adducts resulting from the trans-addition of the N-2-amino group of guanine to the 10-position of (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene. Co-incubation with 7,8-benzoflavone (0.3 microM), an inhibitor of cytochrome P-448, and with 1,1,1-trichloropropene-2,3-oxide (0.2 microM), an inhibitor of epoxide hydrolase, resulted in a marked inhibitory effect (15% of the control binding) and a large increase (300% of the control value) in BP-DNA binding respectively. Induction of aryl hydrocarbon hydroxylase activity in the cultures with 5,6-benzoflavone (10 microM) or benz(a)anthracene (10 microM) caused a decrease (75 and 46% of the control value respectively) in BP-DNA binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzo(a)pyrene↗
PubMed1985

Growth and differentiation of human keratinocytes cultured on eye lens capsules.

The efficiency of the outgrowth of human epidermal and hair-follicle-sheath keratinocytes was studied using three different growth substrates: plastic, type-I collagen and bovine eye lens capsules (the Epicult system). It was shown that the eye lens capsule is the best substrate, since a higher percentage of cultures showed outgrowth, and the outgrowth of epidermal keratinocytes was much more rapid. This effect is related to the faster migration (not proliferation) of cells grown on lens capsules as compared to the two other substrates. The view that lens capsules can replace the basement membrane present in vivo was supported by the finding that two basement-membrane components, i.e., laminin and fibronectin, are present on lens capsules. It was shown that, in cultures grown on lens capsules, bullous-pemphigoid antigen is restricted to the basal layer, indicating that the differentiation of these cells is comparable to that of keratinocytes grown on irradiated, non-viable pig dermis.

Animals↗
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

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↗
PubMed1984

Interaction of crystallins with the cytoskeletal-plasma membrane complex of the bovine lens.

The isolated lenticular plasma membrane-cytoskeleton complex, when analysed by sodium dodecylsulphate-polyacrylamide gel electrophoresis, shows reproducibly a significant amount of crystallins, mainly alpha-crystallin. Evidence is provided that purified plasma membranes from the bovine lens also associate selectively with a limited number of newly synthesized polypeptides on cell-free translation of calf lens polyribosomes and addition of the membranes to the incubation medium. This capability is retained by purified lens membrane junctions. The polypeptides that are selected comprise alpha-crystallin chains (in particular alpha A2-crystallin), actin, vimentin and beta B1a-crystallin. Sequence analysis revealed that the latter has in its N-terminal extension a characteristic Pro-Ala track. The designation 'PAPA-arm' is proposed for this N-terminal region, comprising the alternating Pro-Ala sequence, that has previously also been found in rabbit myosin and might be responsible for anchoring beta B1a-crystallin to lens membranes.

Amino Acid Sequence↗
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↗