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Biomedical subjects

Y Gall

Publications and source records attributed to Y Gall.

At least 37 records · Page 2Linked to original sources
PubMed1998

Minoxidil upregulates the expression of vascular endothelial growth factor in human hair dermal papilla cells.

The hair follicle dermal papilla which controls hair growth, is characterized in the anagen phase by a highly developed vascular network. We have demonstrated in a previous study that the expression of an angiogenic growth factor called vascular endothelial growth factor (VEGF) mRNA varied during the hair cycle. VEGF mRNA is strongly expressed in dermal papilla cells (DPC) in the anagen phase, but during the catagen and telogen phases. VEGF mRNA is less strongly expressed. This involvement of VEGF during the hair cycle allowed us to determine whether VEGF mRNA expression by DPC was regulated by minoxidil. In addition, the effect of minoxidil on VEGF protein synthesis in both cell extracts and DPC-conditioned medium, was investigated immunoenzymatically. Both VEGF mRNA and protein were significantly elevated in treated DPC compared with controls. DPC incubated with increasing minoxidil concentrations (0.2, 2, 6, 12 and 24 mumol/L) induced a dose-dependent expression of VEGF mRNA. Quantification of transcripts showed that DPC stimulated with 24 mumol/L minoxidil express six times more VEGF mRNA than controls. Similarly, VEGF protein production increases in cell extracts and conditioned media following minoxidil stimulation. These studies strongly support the likely involvement of minoxidil in the development of dermal papilla vascularization via a stimulation of VEGF expression, and support the hypothesis that minoxidil has a physiological role in maintaining a good vascularization of hair follicles in androgenetic alopecia.

Cell Culture Techniques↗
PubMed1998

Correlation between percutaneous penetration of methyl nicotinate and sensitive skin, using laser Doppler imaging.

Cutaneous penetration of methyl nicotinate has been investigated in 20 women divided into reactors and non-reactors on the basis of response to 10% aqueous solution of lactic acid. The vasodilation induced was measured using a laser Doppler perfusion imager (LDPI) every 5 min for 1 h after application of methyl nicotinate. The intensity and duration of inflammation generated by methyl nicotinate were used to assess penetration of this chemical in persons with sensitive skin compared to those with normal skin. Significant differences were found between reactors and non-reactors. Reactors showed a significantly increased intensity of response to methyl nicotinate as early as 5 min after application, and for 30 min afterwards, though the duration of inflammation in these 2 groups was the same. Correlation between increased penetration of methyl nicotinate and skin response to lactic acid may suggest increased penetration of water-soluble chemicals in individuals with sensitive skin.

Administration, Cutaneous↗
PubMed1997

pH measurements during lactic acid stinging test in normal and sensitive skin.

Because of the lack of objective signs, the phenomenon of sensitive skin is hard to document. The measurement of the skin pH variations in the nasolabial fold, and on the forearm, after a single application of lactic acid on a preselected sensitive skin population, versus a control one, is proposed as a useful test to detect this kind of population.

Adult↗
PubMed1996

Vascular endothelial cells: targets for studying the activity of hair follicle cell-produced VEGF.

Fetal bovine aortic endothelial cells (FBAEC) were exposed to purified fractions of conditioned medium from cultures of hair dermal papilla cells (DPC) to determine the existence of any vascular endothelial growth factor (VEGF)-like paracrine activity of the latter. Such fractions were tested for stimulation of growth and migration of cultured FBAEC. In addition, VEGF secretion by DPC was measured by radioassay of VEGF receptors using FBAEC as target cells. The results showed that stimulation of FBAEC proliferation and migration following exposure to purified conditioned medium was dose-dependent. Radioreceptor assays of recombinant VEGF and purified DPC-conditioned medium showed competitive VEGF binding in FBAEC.

Animals↗
PubMed1996

Inhibitory effects of bFGF, VEGF and minoxidil on collagen synthesis by cultured hair dermal papilla cells.

Dermal papilla cells of rat vibrissa follicles cultivated in monolayers and in three-dimensional collagen gels show a different morphology in these culture systems. Dermal papilla cells cultured in lattices tend to express morphological features resembling those seen in vivo. Quantification of total collagen by incorporation of 3H-proline in monolayer cultures and in collagen lattices show that the amount of collagen found in dermal papilla cells is higher than that secreted. Moreover, collagen synthesis measured in lattices is reduced to about 50% of that found in monolayer cultures. The influence of growth factors on collagen synthesis by hair dermal papilla cells was investigated. We studied the effects of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and minoxidil on collagen synthesis in monolayers and in lattices. VEGF, bFGF and minoxidil significantly decreased the total amount of collagen. In monolayer cultures, there was approximately a 30% inhibition of collagen production with 5 ng/ml bFGF, 0.1 ng/ml VEGF and 100 ng/ml minoxidil. However, in the lattices this inhibition was reduced to about half. These results suggest that both culture substrate and growth factors influence collagen production by rat hair dermal papilla cells.

Animals↗
PubMed1996

Vascular endothelial growth factor is an autocrine growth factor for hair dermal papilla cells.

The transition of the late anagen to the catagen phase is concomitant with the disappearance of perifollicular capillaries, and therefore cyclical hair growth might depend on the ability of the dermal papilla to synthesize and release soluble growth and differentiation factors toward pre-existing capillaries. We characterized an angiogenic growth factor in the conditioned medium of dermal papilla cells indistinguishable from vascular endothelial growth factor as judged by biochemical and immunologic criteria. In addition, these cells bind vascular endothelial, growth factor on two binding sites and proliferate or migrate in the presence of this growth factor. Moreover, neutralizing antibodies inhibit these biologic effects, confirming that vascular endothelial growth factor might contribute to hair growth either by acting directly on papilla cells or by stimulating the local vascularization.

Animals↗
PubMed1996

Does hormonal skin aging exist? A study of the influence of different hormone therapy regimens on the skin of postmenopausal women using non-invasive measurement techniques.

BACKGROUND AND DESIGN: The skin properties of 98 postmenopausal women with hormone replacement therapy (oestradiol gel or patches) or without hormone replacement therapy were studied using non-invasive techniques: skin thickness with skin echography, skin hydration with a dryness score and measurement of capacitance, skin surface lipids with a Sebumeter and microtopography with image analysis of cutaneous replicas. RESULTS: In this open study we demonstrated an increase in skin thickness and sebum in the treated group in comparison to the untreated group (7-15% according to area for skin thickness, 35% for sebum). Hydration and microtopography were not different in the two groups. CONCLUSIONS: Postmenopausal women who were receiving hormonal substitution have a greater thickness and casual level than untreated women. We therefore suggest that hormonal aging exists and that cutaneous atrophy can be prevented with hormone replacement therapy.

Biopsy↗
PubMed1995

Cell stress and implications of the heat-shock response in skin.

Heat-shock proteins (HSPs), or so-called 'stress proteins' may play an important role in cutaneous pathophysiology. HSPs are a group of highly conserved molecules that are expressed by all cells when subjected to heat or other forms of physical or chemical stress. The physiological roles of stress proteins are varied and are important in stress and nonstress conditions. They bind to other cellular proteins and participate in protein folding pathways during stress and also during the synthesis of new polypeptides. HSPs are also essential for thermotolerance and for prevention and repair of damage caused in DNA after ultraviolet exposure. Although HSPs are expressed in the skin in both epidermis and dermis, HSPs may influence many other cellular processes in the inflammatory and immune skin response. Many authors have speculated on a link between HSPs and human skin disease characterized by inflammation and proliferation.

Heat-Shock Proteins↗
PubMed1994

Confocal microscopy of hair.

Confocal microscopy is an excellent method for studying the localization of fluorescent stains. Used in this way, superior 3D images can be obtained from multiple optical sections with very shallow depth of field. The main advantage of this technique is that the sample is not damaged. We have taken serial confocal sections of hair and via specific image enhancement routines have obtained high-quality 3D images enabling the visualization of cuticle scale and its pattern of distribution. This has been done on various types of hair: bleached, permed and in certain pathological conditions. This first step will allow us to characterize the hair surface in terms of its roughness, and the distribution and form of cuticular scale, parameters that have potential in the assessment of dermocosmetic efficacy.

Hair↗
PubMed1987

[Keratosis follicularis decalvans: nosological discussion of Siemens' disease. Apropos of 3 cases].

We describe 3 cases of keratosis follicularis decalvans (Siemens' disease): a 15 year old boy and a 7 year old boy and his father. They represent 2 different patterns of the disease with different clinical courses and genetic background: an autosomal dominant type of good prognosis with elevated argininemia and absence of follicular atrophy in both father and son, a sporadic type, clinically severe, with follicular atrophy. This raises the question of the nosology of the so-called Siemens' disease, since it includes actually different diseases of variable prognosis.

Adolescent↗
PubMedDate not supplied

Effect of Avène spring water on the activation of rat mast cell by substance P or antigen.

The biological activity of Avène water from two different springs ('Sainte Odile' and 'Val d'Orb') was studied in vitro on rat peritoneal mast cell activation. A dilution-dependent inhibition of both histamine and prostaglandin D2 antigen-induced release was observed when cells were preincubated with both Avène spring waters. They also inhibited histamine release triggered by substance P. The ability of Avène water to inhibit mast cell activation in vitro may be related with its antiallergic and anti-inflammatory properties and its use in hydrotherapy.

Animals↗