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Biomedical subjects

D J Van Neste

Publications and source records attributed to D J Van Neste.

14 recordsLinked to original sources
PubMed1998

Peeling skin syndrome with hair changes.

A 13-year-old boy with typical peeling skin syndrome (PSS) is described. The clinical picture corresponded to the inflammatory variant of PSS (type B). In addition, the patient had gross and microscopic hair anomalies such as trichorrhexis invaginata-like changes, irregular hair shaft torsions and moniliform hair shaft diameter reductions. The observed dysmorphic hair changes are discussed and interpreted as being an integral component of the dermatosis in this case. To the best of our knowledge, such hair anomalies have not yet been described in PSS.

Adolescent↗
PubMed1994

Human hair production by scalp samples grafted onto nude mice. Biochemical data on normal human hair and the genetic defect trichothiodystrophy.

The authors report on a laboratory model for continuous production of human hair during long periods of time. This study shows that the amino acid composition of hairs collected in situ from human scalp was similar to that of terminal hairs produced by the donors' scalp follicles grafted and maintained onto nude mice. A similar experiment was performed with scalp samples from a foetus with trichothiodystrophy (TTD). The amino acid analysis of TTD lanugo hairs and of the TTD shafts produced by grafted scalp specimens was consistent with findings published in the literature: severe decrease of cys (< 50% of control values) and moderate decrease of thr and pro (80% of control values or less) with an increase of ala-asp-ile-leu-lys-met-phe (120% of control values or more). These changes indicate a decrease of high sulphur proteins (HSP) and consequently a relative increase of keratins. Furthermore, when foetal scalp samples were grafted, the lanugo hairs transformed into terminal hairs along with normal initiation of melanisation. Hence, keratin and HSP gene expression and regulation of melanogenesis in the normal and genetically defective TTD human hair follicle grafts appear to be independent of systemic host-related factors, at least during a 6 months follow-up period after grafting. The present experimental evidence further supports conclusions gained from previous assays with normal and TTD variant scalp grafts, i.e. that the nude mouse bearing human scalp specimens may serve as a clinically relevant laboratory model for evaluating regulation of normal and abnormal gene expression in the hair follicle under well controlled experimental conditions.

Adult↗
PubMed1994

The phototrichogram: analysis of some technical factors of variation.

Photographic methods for hair evaluation are frequently proposed as an alternative to more invasive methods (trichogram or biopsy). The reliability in terms of quantitative follow-up of hair growth has not been evaluated properly. We report results of comparative studies of scalp hair evaluation with various photographic methods. Statistically significant findings were a better detection of scalp hairs using the original enlargement x 3 as compared to x 2 (212 vs. 167 hair follicles/cm2) and a more acceptable estimate of linear hair growth rate with 'scalp immersion proxigraphy' (SIP) (0.317 mm/day) as compared with classical phototrichogram pictures where this variable was underestimated by 30% on average (0.27 mm/day). SIP-generated linear hair growth rates were very close to the micrometric method (0.37 mm/day). Therefore SIP x 3 images appear preferable for hair growth monitoring during clinical trials.

Alopecia↗
PubMed1993

Morphological and biochemical characteristics of trichothiodystrophy-variant hair are maintained after grafting of scalp specimens on to nude mice.

Trichothiodystrophy (TTD) is a hair defect associated with abnormal composition of the high-sulphur proteins (HSP). HSP can be modified quantitatively (reduced amount of qualitatively normal HSP: TTD-variant) and qualitatively (TTD). In this study we show that the amino acid composition of hairs collected from the scalp of a patient with TTD-variant (donor) was preserved in hairs produced by donor scalp follicles maintained up to 6 months as grafts on to nude mice. It is the first time that an exceptionally rare, clinically and biochemically well-characterized hair dysplasia has been maintained under laboratory conditions for a long period of time. The linear growth rate of TTD-variant hairs was similar to that of control hairs grown under comparable conditions. The persistence of disease-specific abnormalities in the hair shaft indicates that the TTD-variant mutation is expressed without significant quantitative modifications, and appears independent of systemic host-related factors. This model may serve as a clinically relevant working platform for evaluating regulation of abnormal gene expression in the hair follicle under well-controlled experimental conditions.

Amino Acids↗
PubMed1989

Quantitative time course study of the skin response to histamine and the effect of H1 blockers. A 3-week crossover double-blind comparative trial of cetirizine and terfenadine.

A controlled, randomized, double-blind, crossover study was performed in 10 healthy volunteers to compare changes of cutaneous blood flow values (CBFV) determined by laser Doppler flowmetry before and after intake of a capsule containing either 10 mg cetirizine or 60 mg terfenadine. After the determination of the initial response to the anti-H1 agents, drugs were taken daily (cetirizine 10 mg, terfenadine 120 mg) over a 3-week period and the cutaneous response to histamine and saline was evaluated weekly, exactly 4 h after the last drug intake. The following significant variations were observed (analysis of variance for repeated measurements, p less than 0.05): (1) there is a decrease of histamine-induced wheal and flare under antihistamines (anti-H1), cetirizine being more potent than terfenadine; (2) CBFV, measured on the usual flare area, i.e. at 1 cm of the site of agonist injection, decreased after drug intake. There was a gradual increase of the CBFV inhibition over the 3-week follow-up, cetirizine being more effective than terfenadine, and (3) at the site of agonist injection, reduction of the edematous wheal was associated with significant increases of CBFV after drug intake. This quantitative pharmacologic in vivo assay on the agonist action indicates that at lower doses, cetirizine has a significantly higher anti-H1 activity than terfenadine and that this effect is maintained over a 3-week period. There was no tachyphylaxis.

Adult↗
PubMed1989

[Invasive and non-invasive studies of the protective action of a silicon-containing cream and its excipient in skin irritation induced by sodium laurylsulfate].

The purpose of our study was to evaluate the protective effect of a new silicone-containing barrier-cream (Anthydro) and its vehicle (Anthydro without silicone) in the prevention of cutaneous irritation by detergents. We therefore planned a study in several stages, using an anionic surfactant well known for its irritant properties: sodium laurylsulphate (SLS) in aqueous solution. In a first series of experiments, the protective effect of the Anthydro cream against SLS was studied by invasive methods on guinea-pigs in order to determine histologically the protective effect of the cream when a 10 p. 100 SLS solution was applied on the skin under occlusion during 24 hours (Square chambers, Van der Bend). Typical and reproducible lesions were apparent, and the protected sites were compared with the unprotected sites. In parallel, we used non-invasive methods (conductivity, transepidermal water loss and cutaneous blood flow) to determine in humans the protective effect of Anthydro cream in comparison with unprotected sites after application during 24 hours of patches soaked with a 5 p. 100 SLS solution on the forearms of 13 adult and healthy volunteers (Silver patch tests, Van der Bend). In both experiments the Anthydro cream was effective in reducing the SLS-induced cutaneous irritation. In a second series of experiments, the Anthydro barrier-cream was compared with its "base" (Anthydro without silicone) in terms of effectiveness, following the same experimental procedure (invasive on guinea-pigs, and non-invasive on humans). The base was shown to be effective in protecting against irritation. However, the histological lesions were less intense when the skin was protected by Anthydro than by its vehicle. Concerning the non-invasive methods in humans, no significant statistical differences appeared in the measurement of various parameters between the sites protected by Anthydro and the sites protected by the vehicle. These results lead us to suggest the existence of an essentially mechanical protective effect in which the silicone plays a very small part in terms of effectiveness. These experimental results necessitates further investigations to be extrapolated to occupational conditions without tests performed in industries and well-conducted epidemiological investigations.

Animals↗
PubMed1988

Distribution pattern of psoriatic keratoblasts: computer-assisted image-analysis for combined evaluation of DNA synthesis and expression of 67 kD keratin polypeptides in the epidermis of stable plaques of psoriasis.

Psoriatic epidermis is characterized by increased DNA synthesis and disturbed differentiation. Even though these processes are closely associated, most investigations do not give insight into temporal/spatial relationships between both events. We previously developed a double labeling method for the simultaneous demonstration of the germinative and differentiated epidermal compartments in normal human skin by using tritium-labeled thymidine ([3H] Thd) incorporation and immunoperoxidase staining of 67 kD keratin polypeptides. In this paper we report the results of combined evaluation of these compartments in stable plaques of psoriasis. Scanning of skin sections with an automatic image analyzer allows objective quantification of areas of total epidermis, 67 kD+ differentiated epidermis and numbers of [3H] Thdr+ nuclei. Our data indicate that the 67 kD- undifferentiated psoriatic epidermis is expanded. Increased numbers of [3H] Thd+ basal and suprabasal psoriatic keratinocytes are present and most of them (97.9%) pertain to the 67 kD- compartment. Keratin identification in scales taken from the same sites showed a variable but distinct decrease of 67 kD keratin polypeptides. Hence, the hyperplastic epidermis of stable plaques of psoriasis is characterized by the presence of increased numbers of [3H] Thd+ cells, which primarily belong to the undifferentiated (67 kD-) basal and suprabasal compartments, especially in the lowermost parts of the elongated interpapillary rete ridges. These changes are associated with a relative decrease of synthesis of 67 kD polypeptides and the presence in the scales of keratins that confer a characteristic hyperproliferative epidermal keratin pattern to the psoriatic plaque.

Cell Differentiation↗
PubMed1986

Similar epidermal changes in hyperkeratotic scabies of humans and pigs.

We compared some morphological and biochemical aspects of the epidermal changes occurring in hyperkeratotic scabies in humans and domestic pigs. Clinically and histologically, pig skin alterations look very similar to those observed in humans, i.e., brittle hyperkeratosis with parakeratotic crusting and thickening of the epidermis. Parakeratosis seems to correspond to previous passage of scabies mites through the incompletely differentiated layers of the epidermis. Indeed, by serial sectioning we observed beneath the stratum corneum cellular lysis some distance ahead of the mouth parts of the parasites. Epidermal cells surrounding this initial epidermolytic focus finally underwent disturbed terminal differentiation and appeared as parakeratotic cells. In pigs we observed intraepithelial microabscesses, but we rarely observed these in our human subjects.

Animals↗
PubMedDate not supplied

Contrast enhanced phototrichogram (CE-PTG): an improved non-invasive technique for measurement of scalp hair dynamics in androgenetic alopecia--validation study with histology after transverse sectioning of scalp biopsies.

Global changes of scalp hair represent the cumulative end result of discrete changes of individual hair follicle structure and/or function. Monitoring of such changes requires an accurate non-invasive method. The phototrichogram (PTG) appears to be an appropriate choice to do so. However, a known weakness of the method is the lack of detection of less pigmented or thinning hair. Balding scalp of male subjects with androgenetic alopecia (AGA) was analysed with our previously published PTG method and with contrast enhanced (CE-)PTG followed by biopsy and transverse section examination with the light microscope. As compared with PTG, the CE-PTG method significantly improved detection not only of thin but also of thick hair. Equal numbers of thick (diameter > 40 mm) hair were detected with CE-PTG and with histology. CE-PTG was also able to detect the severely miniaturised hair fiber (down to 8 mm diameter) and was comparable to scalp biopsy analysis. The latter could identify hair fibres, which did not reach the scalp surface, a measure that is considered as not clinically significant. All growth stages - anagen, catagen and telogen - as well as the empty follicle stage could clearly be observed with CE-PTG. Staging of the more severely affected hair follicles was not always possible neither with CE-PTG nor histology - even with serial sectioning. The finding of such technological advantages makes the CE-PTG a first choice method for detailed analysis of hair cycling in androgenetic alopecia - a scalp disorder characterised by extreme hair follicle miniaturisation, decreased hair pigmentation and hair thinning.

Adult↗
PubMedDate not supplied

pH influence of surfactant-induced skin irritation. A non-invasive, multiparametric study with sodium laurylsulfate.

Even though various experimental methods have been proposed for in vitro testing of detergents such as LSL (sodium laurylsulfate) no absolutely relevant clinical information can be inferred from them as to the irritancy of a given compound. In particular the relative importance of pH needs further assessment. This study reports on in vivo evaluation of skin function changes under given experimental conditions with SLS applied at 3 different pH values. There is a dramatic increase of transepidermal water loss (TEWL), i.e. a substantial reduction in the barrier function of the skin, when SLS is applied under occlusion for 48 H. The alkaline control solution (NaOH pH 9) induced low-grade, but significant TEWL increases, as compared to the other controls (distilled water pH 7; HCl pH 5), which had no influence on TEWL. The changes obtained with the controls were much lower than those observed with SLS. The barrier-function changes induced by the surfactant SLS could, however, promote transepidermal passage of acid and/or alkaline molecules, hence increasing toxic damage of the skin; yet no such effects could be observed, indicating that the main effects are due to detergency. Assessment of cutaneous blood flow values (CBFV) by laser Doppler velocimetry showed increased values after SLS. When pH-adjusted SLS solutions were compared, there was neither a difference in relation to pH nor did the control solutions induce any significant CBFV change. This study reveals that TEWL and CBFV are probably the most reliable methods to investigate acute irritancy by SLS. Accordingly, pH cannot be considered as a major contributive factor of irritancy when SLS solutions are applied under occlusion (48 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗