PubMed Health⌕ Search

Biomedical subjects

Y Gall

Publications and source records attributed to Y Gall.

At least 19 recordsLinked to original sources
PubMed2003

[Lipids and skin inflammation: role of phospholipases A2].

Phospholipases A2 (PLA2) are enzymes that catalyse the hydrolysis of glycerophospholipids at the sn-2 position, generating free fatty acids and lysophospholipids. At present, PLA2 family consists of 12 groups. PLA2 are involved in many pathophysiological processes such as barrier function, eicosanoid production, and inflammation. They are implicated in inflammatory diseases of the skin: psoriasis, eczema, atopy. The presence of PLA2 activity has been demonstrated several years ago, however the precise localization of all these PLA2 in the epidermis and its appendages has to be determined. Further studies have shown that these enzymes are expressed in various layers of epidermis. This differential localization suggests different roles for each PLA2 in skin physiology and during inflammation.

Dermatitis↗
PubMed2003

Radiation-induced skin fibrosis after treatment of breast cancer: profilometric analysis.

BACKGROUND/AIM: Treatment of breast cancer involves an association of conservative surgery and radiotherapy. This implies various cutaneous complications, well known for their clinical and histological aspects. Little data are available concerning modifications of the cutaneous microrelief after radiotherapy. We have done a profilometric analysis of the skin of breast cancer patients treated with surgery and radiotherapy. The results obtained on the irradiated breast have been compared with the ones of the controlateral normal breast. METHODS: Twenty women, 43-55 year old were enrolled in the study 6-16 months after the end of a treatment associating conservative surgery and radiotherapy for breast cancer. Imprints using a silicone rubber material were performed over symmetrical areas of the treated breast and the controlateral one. All measures were performed over the upper-medial quadrant of each breast. The imprints are then blindly analysed using an image analyser. The following parameters were measured: RA (average roughness of the skin), RZ (average of the furrows depth), RS (residual length), Rn (number of furrows) and AR (space between the furrows). RESULTS: The comparison of the imprints shows important modifications of the microrelief after irradiation. We observe a slight increase of the skin roughness (RA: 26, 39 +/- 2, 58 versus 21, 84 +/- 1, 59), a significantly increase of the furrows depth (RZ: 121, 66 +/- 10, 46 versus 101, 26 +/- 6, 99) along with an increase of the residual length (RS: 580, 60 +/- 60, 60 versus 450, 46 +/- 48, 43). The number of furrows has not significantly decreased but the space between the furrows has increased on the irradiated breast. CONCLUSION: This study shows a breakdown effect of irradiation on the skin in correlation with the fibrosis inducing by ionising radiation. The imprints modifications are clearly different from those usually observed in the ageing process. Our results can be a basis for studying the effects of treatments on cutaneous complications linked to the radiation-induced fibrosis.

Adult↗
PubMed2002

Environmental pollutants and skin cancer.

We are increasingly exposed to environmental pollution. Pollutants can be inhaled, ingested or come into contact with the skin depending on the form in which they occur. On metabolization, activation, or accumulation, pollutants can become extremely toxic for the vital organs and this is often related to a strong genotoxic effect. Since the skin acts as a barrier between the organism and the environment, it is frequently directly exposed to pollution. It is very often degraded by polluting agents and acts as an inlet toward other tissues. Numerous studies in man recognize and demonstrate the carcinogenic power of certain pollutants in the digestive and respiratory tracts. The "pollutants" that react most specifically with the skin are: ultraviolet radiation, polycyclic aromatic hydrocarbons (e.g., benzo[a]pyrene), volatile organic compounds (e.g., benzene), heavy metals, and ozone. Ultraviolet radiation, a "physical" pollutant, has been described as being the factor responsible for most skin cancers in man. The genotoxicity of UV light is well documented (type of lesion or mutation, etc.) and its carcinogenic effect is clearly demonstrated in vivo in man. A few epidemiological studies describe the carcinogenicity of certain pollutants such as arsenic or lead on the skin. However, most of the evidence for the role of pollutants in skin cancers comes from in vivo animal studies or from in vitro studies (e.g., PAHs). In this report, different studies are presented to illustrate the research strategies developed to investigate the mechanism of action of "chemical" pollutants and their potential role in human skin pathology. All the study models and the associated techniques of investigation are tools for a better understanding and thus more efficient prevention of the deleterious effects caused by the environment.

Animals↗
PubMed2002

[Implication of VEGF, steroid hormones and neuropeptides in hair follicle cell responses].

Human hair follicles progress independently through the anagen, catagen, telogen and latency phases that correspond to growth arrest and hair shedding before initiation of a new anagen phase. Hair follicles are self-renewing and contain reservoirs of multi-potent stem cells. Identification of the messenger molecules and pathways operating in the growth and cycling of hair follicles, have provided substantial data. However, only a limited number of these signals is well understood. The specific response of hair follicle cells to these signals is correlated with the expression of their corresponding receptors. What regulates these responses? In this review, we will focus on the hair cycle and its control mechanisms. We will provide some elements in answer to these questions and present some of the markers of hair follicle cells, and hormonal and vascular growth factors, which may regulate respectively hair follicle cell metabolism and cycle, and the neuropeptide impact on hair follicle response and hair growth. The results of our study show the modifications in various expression patterns of receptors in dermal papilla cells, and demonstrate the cross-interaction between these different components. In conclusion, we present an accumulation of evidence suggesting that the regulation of hair growth requires a combination of hormonal, vascular and neuropeptide approaches that will provide further insight in defining new treatments for hair loss.

Alopecia↗
PubMed2001

Use of thigh pressure cuffs to modulate simulated microgravity-induced changes in the skin measured with high-resolution B-scan ultrasound.

OBJECTIVE: The aim of the present study was to evaluate the fluid shift in a simulated microgravity experiment and to test the use of thigh cuffs to help alleviate the problem. METHODS: The change in skin thickness was assessed by a 20 MHz B-scan ultrasound device. This was performed on eight volunteers who underwent two successive 7-day periods of -6 degrees anti-orthostatic bed-rest, with or without the daytime use of thigh cuffs. The thigh cuffs were used to counteract the development of facial oedema. RESULTS: In the control group (without thigh cuffs), the results showed a steady increase in skin thickness of the combined dermis and hypodermis of the forehead and a reduction of the thickness of this tissue on the tibia. For the countermeasure group, although thigh cuffs were only employed during the daytime - being removed at night - their use reduced the amplitude and kinetics of the fluid shift, resulting in greater beneficial effects at the end of the day than early in the morning. CONCLUSION: These results of objective measurements of skin made using a non-invasive high frequency ultrasonography method confirm reports by cosmonauts of a reduction in facial oedema and a more 'comfortable' adaptation to microgravity by the use of thigh cuffs during space flight. This system is potentially promising for investigating fluid shifts in the skin and may prove useful in the evaluation of some oedematous skin diseases, as well as their therapy.

Adult↗
PubMed2001

Skin topography measurement by interference fringe projection: a technical validation.

BACKGROUND/AIMS: The quantitative analysis of skin topography is frequently used in cosmetology to evaluate the efficacy of hydrating or anti-wrinkle creams (micro-topography studies) or creams for slimming or to alleviate stretch marks (macro-topography studies). Numerous methods involving the three-dimensional (3-D) reconstruction of the topography from silicone replicas have been developed. Some of the main techniques applied include optical profilometry based on the reflection of oblique lighting or on transparency, and profilometry by laser focusing or triangulation. METHODS: We chose to test the Dermatop system developed by Eotech Co., which is based on interference fringe projection profilometry associated with the Toposurf surface processing software. Owing to the system's principle of operation, we first ran three experiments to evaluate the influence of ambient lighting on the 3-D reconstruction and the surface roughness parameters, the influence of the calibration device built into the acquisition system and the influence of calibration in terms of ambient lighting correction. We then evaluated the accuracy, the repeatability and the reproducibility of the measurements provided by the system from known metal topographic standards and skin replicas. RESULTS: It was seen that external lighting can cause variations in the calculation of parameters SPa, SPt and SPtm which can reach error levels of about 5% if the operator does not almost systematically calibrate the apparatus between each measurement. These three experiments enabled us to standardise the protocol for the acquisition of 3-D information, in order to minimise the lighting problems and yet respect the requirements for routine studies. The correlation coefficient between the theoretical values and the mean of experimental values was 0.9955 for parameter SPa and 0.9983 for parameter SPtm. Repeatability presented variations of under 4%, irrespective of the parameters, and reproducibility of under 6%. CONCLUSIONS: The technique provides very satisfactory results from the point of view of accuracy, repeatability and reproducibility. It is an excellent compromise between cost, accuracy and the time required.

Dermatology↗
PubMed2001

Nonablative remodeling: clinical, histologic, ultrasound imaging, and profilometric evaluation of a 1540 nm Er:glass laser.

BACKGROUND: Nonablative remodeling has been recently proposed as an alternative to CO2 and Er:YAG resurfacing. OBJECTIVE: To evaluate the efficacy and safety of a 1540 nm Er:glass laser with contact cooling in nonablative skin remodeling, focused on perioral and periorbital rhytides. METHODS: Sixty patients (mean age 47 years), Fitzpatrick skin types I-IV were treated four times over 6-week intervals. Patients were evaluated using digital photographs, histology, ultrasound imaging, and profilometry with silicone imprints in order to quantitate the degree of clinical improvement. RESULTS: All subjects reported subjective improvement in the quality and visual aspect of their skin. This was confirmed by a 40.2% reduction of anisotropy (P <.001) 6 weeks after the fourth treatment. Ultrasound imaging demonstrated a 17% increase of dermis thickness (P <.005). Biopsy specimens showed evidence of new collagen formation. CONCLUSION: This study has clearly demonstrated that irradiation with 1540 nm Er:glass laser can lead to new collagen formation, dermis thickening, reduction of anisotropy of the skin, and clinical improvements. The lack of adverse effects confirmed that this 1540 nm laser emitting in a pulsed mode coupled with an efficient cooling system is safe.

Adult↗
PubMed2000

Microrelief of the skin using a light transmission method.

The recently developed Skin Visiometer, based on light transmission through blue-coloured silicone replicas, was used to study skin microrelief. Calibrated metal plates displaying lines with depths between 6 and 361 microns, were used to determine the accuracy, sensitivity and reproducibility of the technique as well as the parameters of importance during measurement. The precision of the measurements was particularly good between 10 microns and 361 microns. The sensitivity of the method was between 10 and 20 microns. Replicas of volar forearm skin were taken from four groups (n = 15) of male and female volunteers in the age ranges 20 to 30 years and 55 to 65 years. In addition to the instrumental roughness parameters (Rz, Rt, Rm and Ra), the surface of the furrows, the number of primary and secondary lines and the number of intersections were determined. For both sexes, significantly lower values were observed for Rz, Rm and Rt in the younger age group than in the older age group. In addition, the numbers of primary and secondary lines and the number of intersections were higher, pointing to a more structured microrelief in younger forearm skin. Diurnal rhythm, the relative humidity of the measuring room and the position of the forearm were found to be significant factors, while room temperature and precleansing of the skin with mild products were not. Following the application of a hydrating cream (twice daily for 14 days) to the forearm skin of the older female age group, the Rz, Rt, Rm and Ra decreased, while the other parameters measured, except for the surface taken in by the lines, increased, indicating that the microrelief was modified towards the typical pattern observed in young skin.

Adult↗
PubMed2000

Characterisation of gravity-induced facial skin oedema using biophysical measurement techniques.

BACKGROUND/AIMS: In humans, the microgravity environment can be expected to induce swelling of facial tissues and shrinking of the tissues in the lower limbs, together with a loss in body weight. To evaluate fluid shifts in skin, the head-down bed-rest model was used. The aim of the present study was to evaluate the appearance of facial oedema in subjects undergoing anti-orthostatic bed-rest at an angle of -10 degrees. METHODS: The forehead of each of four subjects was measured before and after 1, 10 and 24 h in this head-down tilt position. At these time points, interstitial fluid migration and facial oedema were assessed using a high resolution B-scan ultrasound and a device for measuring the skin's mechanical properties. RESULTS: The results obtained showed a progressive increase in dermal thickness and initial stress, and a reduction in stiffness and elasticity of the skin during the study period. CONCLUSIONS: This preliminary study has demonstrated the feasibility of the method in measuring fluid displacement and retention in the skin. Furthermore, it highlights the influence of fluids on the mechanical behaviour of the skin. These techniques could be used for studying the redistribution of liquid masses during periods spent in space.

Aerospace Medicine↗
PubMed2000

Identification of pancreatic type I secreted phospholipase A2 in human epidermis and its determination by tape stripping.

Phospholipases A2 (PLA2) catalyse the release of fatty acids from the sn-2 position of phospholipids and have been suggested to play a key part in permeability barrier homeostasis. Using a sensitive and versatile fluorometric method, significant PLA2 activity has been detected in both human skin homogenates and tape strippings of stratum corneum. Based on various properties (resistance to heat and sulphuric acid treatment, neutral optimal pH, absolute requirement for millimolar calcium concentrations, inhibition by dithiothreitol and p-bromophenacyl bromide, and resistance to a trifluoromethyl ketone derivative of arachidonic acid, AACOCF3, a specific inhibitor of cytosolic PLA2), this enzyme was characterized as a secretory PLA2 (sPLA2). Immunohistochemistry revealed strong labelling of type I pancreatic sPLA2 at the stratum corneum-stratum granulosum junction, type II sPLA2 being undetectable. An increase in PLA2 activity in tape-stripped material from the deepest level of the stratum corneum was correlated with partial morphological disappearance of type I sPLA2 immunolabelling. Our data thus provide the first convincing evidence that pancreatic sPLA2 is significantly expressed in human epidermis, where it might participate in the accumulation of free fatty acids contributing to the permeability barrier. In addition, our method for determining PLA2 activity in easily available tape strippings should allow further clinical studies aimed to explore possible PLA2 abnormalities in various dermatoses.

Adolescent↗
PubMed2000

Studies on epidermis reconstructed with and without melanocytes: melanocytes prevent sunburn cell formation but not appearance of DNA damaged cells in fair-skinned caucasians.

To assess the photoprotective role of melanocytes in the epidermis, we studied the effects of ultraviolet B on an epidermis reconstructed with and without melanocytes. To address more specifically the role of melanin in fair-skinned individuals, experiments were done with cells obtained from human skin of low phototypes (II-III). To study the effect of constitutive melanin and possibly that of newly synthesized melanin precursors, a single dose of ultraviolet B (0.10 or 0.15 J per cm2, corresponding to a 4-5 minimal erythema dose in vivo) was administered to reconstructs and the effects were monitored over the first 24 h. When reconstructs with and without melanocytes were compared, no difference was found for DNA damage/repair assessed with antibodies to cyclobutane pyrimidine dimers and 6-4 photoproducts. More necrotic/apoptotic cells, however, were noted 24 h following ultraviolet B irradiation in reconstructs lacking melanocytes. Twenty-four hours following ultraviolet B irradiation the number of necrotic/apoptotic cells and the number of cyclobutane pyrimidine dimer positive cells was coarsely concentration-dependent. The number of cyclobutane pyrimidine dimer positive cells, however, was independent of the type of reconstruct used (with/without melanocytes). In conclusion, low phototype melanocytes seem to protect epidermal basal cells against ultraviolet B-induced apoptosis/necrosis and may preserve the overall integrity of the epidermis after ultraviolet B irradiation. On the contrary, such melanocytes do not seem to have a protective role against DNA damage and may not prevent cancer.

Adult↗
PubMed2000

Evaluation of cutaneous modifications in seventy-seven growth hormone-deficient children.

Cutaneous parameters such as dermal thickness, stiffness, elasticity, skin surface lipid and hydration were evaluated using noninvasive methods in 77 growth hormone-deficient (GHD) children before replacement therapy and in 70 non-GHD children. We showed that in GHD children, dermis was thinner (0.70 +/- 0.10 vs. 0.80 +/- 0.10 mm, p < 0.0001 for prepubertal children and 0.81 +/- 0.10 vs. 0.94 +/- 0.11 mm, p < 0.0001 for pubertal children), stiffer (178.5 +/- 57.3 vs. 113.09 +/- 37 kPa, p < 0.0001 for prepubertal children and 172.5 +/- 61.7 vs. 117.3 +/- 42.5 kPa for pubertal children, p < 0.001) and less elastic (0.44 +/- 0.09 vs. 0.39 +/- 0.06 (nonelasticity index), p < 0.01 for prepubertal children and 0.39 +/- 0.05 vs. 0.33 +/- 0.04, p < 0.001 for pubertal children) compared to controls. Fourteen GHD children were re-evaluated after 1 year of GH treatment: dermal thickness and skin stiffness were significantly improved (p < 0.001 and p < 0.05 respectively) while elasticity was not modified. During the same period, 11 controls did not show any significant cutaneous modification. IGF-1 values, but not IGFBP-3 values, correlated positively with dermal thickness in GHD children, before and after 1 year of GH treatment. To conclude, GHD children exhibited specific cutaneous modifications. In a subset of GHD children, we showed that these modifications were influenced by GH treatment. More extensive studies are needed to see if these changes correlated with other GH effects.

Adolescent↗
PubMed1999

In vitro main pathways of steroid action in cultured hair follicle cells: vascular approach.

The known role of steroids on the hair follicle leads us to investigate their effects on hair follicle cell angiogenic responses in vitro. We verified, using the immunohistochemical technique, whether human occipital scalp follicle cells express steroid receptors in vitro. We showed that androgen and estrogen receptors were expressed by dermal papilla cells (DPC) and keratinocytes from the outer root sheath in vitro. With regard to steroidal enzymes (type I and II 5alpha-reductases and Cytochrome-p-450-aromatase), the type I 5alpha-reductase gene is much more expressed in DPC than in dermal fibroblasts; however, the type II 5a-reductase gene is transcribed more in dermal fibroblasts than in DPC. The transcription of the two 5alpha-reductase isoform genes in cultured DPC is regulated by a 5alpha-reductase inhibitor. We also demonstrated that DPC, dermal fibroblasts, and outer root shealth keratinocytes expressed cytochrome-p-450-aromatase. Using ELISA and reverse transcriptase-polymerase chain reaction, we investigated the role played by some steroids (estrogens, androgens, antiandrogens) in the modulation of vascular endothelial growth factor (VEGF) expression by DPC. The association of different treatments of DPC (5alpha-reductase inhibitor and androgen receptor antagonist) shows a great stimulation of VEGF and aromatase expression. Strong stimulation of VEGF protein and gene expression is observed in the presence of 17beta-estradiol. Also, the concentration-dependent inhibition of VEGF expression by DPC using the cytochrome-p-450-aromatase inhibitor, confirms the involvement of this estrogenic pathway in the regulation of VEGF expression in vitro.

Androgens↗
PubMed1999

A mineral sunscreen affords genomic protection against ultraviolet (UV) B and UVA radiation: in vitro and in situ assays.

Ultraviolet (UV) radiation has been shown to be responsible for different biological effects on human skin, including the initiation of photocarcinogenesis. Both UVB and UVA have been described as mutagenic, but the processes by which they alter the DNA are different. Although cells can repair DNA damage, some deleterious mutations nevertheless appear and can promote cancer. The risk of photocarcinogenesis is acknowledged and the frequency of photogenodermatosis is increasing. In order to evaluate the protection efficacy of a high sun protection factor (SPF) mineral sunscreen against UVB- and UVA-induced genomic alterations, we have followed two approaches. First, we have tested the sunscreen for its ability to decrease the unscheduled DNA synthesis response in vitro in human fibroblasts, as an indirect measure of UVB-induced lesions (0.005 and 0.01 J/cm2), and second, we have verified its ability to reduce the in situ end-labelling intensity in human skin as a direct measure of UVA-induced single-strand breaks (10 J/cm2). Microscopic analysis clearly demonstrated the protective effect of the sunscreen against UVB and UVA. A dose-dependent effect of mineral sunscreens was observed. There was also a relationship between the SPF and genomic protection. By limiting the accumulation of UV-induced lesions on DNA, this mineral sunscreen could limit the mutation frequency.

Adult↗
PubMed1999

Inhibitory effects of retinoids on vascular endothelial growth factor production by cultured human skin keratinocytes.

BACKGROUND: Vascular endothelial growth factor (VEGF), a potent angiogenic factor and vasodilator, is strongly expressed by epidermal keratinocytes in many angiogenesis-dependent skin disorders. Retinoids may modulate VEGF in skin and this may be related to an effect on rosacea. AIM: To investigate the effect of retinaldehyde on VEGF production by human keratinocytes. METHODS: The effects of different concentrations of retinoids (all-trans-retinal and all-trans-retinoic acid) on VEGF production by cultured human skin keratinocytes in both cell extracts and supernatants were determined. Expression of VEGF was analyzed by enzyme-linked immunosorbent assay (ELISA) and RT-PCR. RESULTS: The amount of cell-associated and secreted VEGF strongly decreased with retinoid concentration (e.g. 48, 69% inhibition at 0.1 microM all-trans-retinal and -retinoic acid, respectively, in the supernatants). In parallel, approximately 25% inhibition of VEGF mRNA expression was obtained in the presence of 0.01 microM all-trans-retinal. CONCLUSION: The decrease in VEGF expression by keratinocytes on contact with retinoids may prevent skin neoangiogenesis in certain skin diseases.

Cells, Cultured↗
PubMed1999

Retinaldehyde alleviates rosacea.

BACKGROUND: Anecdotal observations suggest that retinoic acid may be effective in mild rosacea. AIM: Our aim was to investigate, by an exploratory clinical and instrumental study, the effects of a topical formulation with the retinoic acid precursor retinaldehyde, in patients with vascular signs of facial rosacea. METHODS: Female patients were treated with a 0.05% retinaldehyde cream that was applied once daily for 6 months. Clinical assessments of persistent erythema and telangiectasia were performed every month, using a 4-point severity score (absent to severe). The clinical response for each parameter was defined as a decrease of at least 1 grade in the severity score. In addition, erythema was further evaluated by measurement of the a* parameter, using a spectrophotometer on lesional and nonlesional areas. RESULTS: A total of 23 women comprised the study population. At baseline, 10 patients had diffuse erythema, 3 patients had isolated telangiectasia and 10 patients had both. During retinaldehyde treatment, a clinical response was revealed in about 75% of the patients with erythema, after 5 months (p < 0.05). Similarly, isolated telangiectasia responded to retinaldehyde, although to a lesser extent and after a longer period of treatment (46% responders after 6 months, nonsignificant). Using the spectrophotometer, the a* parameter diminished in patients with erythema by about 15%, after 2 months of treatment (p = 0.001). CONCLUSION: This study indicates that retinaldehyde has beneficial effects on the vascular component of rosacea.

Administration, Topical↗
PubMed1998

An in vivo method for measuring the mechanical properties of the skin using ultrasound.

In this study, we report a new and original device called the "echorheometer," comprising a suction system with an ultrasound scanner (A-mode, TM-mode and B-mode) that enables the simultaneous visualization and measurement of the deformation of skin structures in vivo. With the scanner described here, high resolution is obtained using a strongly focused, wide-band 20-MHz center frequency transducer, with an axial resolution of 0.07 mm. This device can determine, noninvasively, not only those skin structures that are involved in the deformation, but also their morphological variation and their extent of involvement with the degree of stress applied. Using this device, the behavior of the dermis and subcutaneous fat, while under suction, was investigated on the volar forearm of 10 volunteers. The results showed that the resistance to the applied vertical stress is essentially due to the dermis rather than the subcutaneous fat, and that there is a certain amount of infiltration of fluid into the tissues under suction. In addition, it was shown that the dermal response to an applied suction is initially due to its own natural tension and that, with increasing deformation, the intrinsic dermal elasticity has a greater contribution to the resistance of stress. With this information, we hope to develop a mechanical model to define appropriate mechanical parameters for skin. This will allow the evaluation of changes in the dermis and also enable therapeutic intervention to be assessed. Furthermore, it could also be applied to studies of skin ageing and the assessment of cosmetic product efficacy (emolliency, hydratation, etc.).

Adult↗