Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Skin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed1986

Evaluation of monkey skin as a model for in vitro percutaneous penetration and metabolism of [3H]T-2 toxin in human skin.

Discs of abdominal skin (obtained from humans and hybrid monkeys at autopsy) were mounted on diffusion cells. The epidermal surfaces were dosed with [3H]T-2 dissolved in dimethyl sulfoxide (DMSO). The rate of [3H]T-2 penetration (expressed as ng/cm2/hr) through human skin was 0.38 +/- 0.10 and 3.85 +/- 0.96 (means +/- 95% confidence limit) when dosed with 74 and 582 ng/cm2, respectively. [3H]T-2 penetrated through monkey skin at the rate of 0.37 +/- 0.14, 0.80 +/- 0.43, 4.13 +/- 1.71, and 6.55 +/- 3.45 when dosed with 70, 155, 555 and 1063 ng/cm2, respectively. Analysis of the receptor fluid bathing human skin revealed 15% of the radioactivity was associated with T-2, 71% with HT-2 toxin (HT-2), and 6.3% with an unknown metabolite more polar than HT-2. The radioactivity in the receptor fluid bathing monkey skin was associated with T-2 (87%) and HT-2 (1.0%). The results are consistent with the hypothesis that metabolism of T-2 occurred during penetration through the excised skin and did not occur in the receptor fluid due to enzymes leaching out of the skin. These findings indicate that excised monkey skin is a good model for T-2 penetration through human skin when DMSO is the vehicle, but that dermal metabolism of T-2 is different in these two species.

Animals↗
PubMedDate not supplied

Other uses of homologous skin grafts and skin bank bioproducts.

The main use of homologous skin grafts or grafts of related bioproducts is in the treatment of severe burns. However, various new clinical and experimental sectors, in which this type of skin substitute can be useful, have recently emerged. The main new clinical indications for skin allografts include: skin loss, surgical wounds and bullous diseases. In these fields donor skin can be used for different purposes: as a physiological biological dressing to control pain and protect deep structures such as tendons, bones, cartilage and nerves, and to promote reepithelization with a significant reduction in healing time, and as skin substitute with dermal tissue to guide repair and make it as physiological as possible. In particular, skin bank bioproducts are currently used in the treatment of several conditions such venous and arterial leg ulcers, pressure ulcers, diabetic foot ulcers, pyoderma gangrenosum, post traumatic lesions, Mohs surgery, reconstructive surgery, wound cover in critical areas, aesthetic surgery, congenital epidermolysis bullosa and Lyell's syndrome. Skin bank bioproducts have also been used for experimental indications, to study in vitro toxicology and in vitro skin biology. Recently the demonstration that de-epidermized dermis (DED) has all the characteristics of an excellent dermal substitute into which various types of cells can be introduced and made to develop, opens exciting new possibilities of research in the field of wound healing and tissue engineering. Our preliminary observations seems to indicate that CD 34+ stem cells from umbilical cord blood can survive in DED and in a few weeks populate collagen bundles. The observation of tubular structures without lumina close to collagen bundles as well as clusters of epithelioid or fibroblast-shaped cells may represent aspects of differentiation of CD 34+ stem cells. More detailed and sophisticated studies are clearly needed to answer all the questions that these initial observations pose. Anyway the 3-dimensional model proposed seems to be suitable for the study of the behaviour of peripheral CD 34+ and perhaps also other types of stem cells in 3-dimensional dermal matrix.

Humans↗
PubMed2003

The SCID-hu Skin mouse as a model to investigate selective chemokine mediated homing of human T-lymphocytes to the skin in vivo.

Here we report the establishment of an in vivo mouse model that allows monitoring of human T cell migration into human skin. This model is based on the use of severe combined immunodeficiency (SCID) mice transplanted with human skin (SCID-hu Skin mice). Adoptively transferred human T helper (Th)2 cells obtained from atopic dermatitis skin lesions or peripheral blood T cells selectively migrate to the human skin grafts of these SCID mice in response to defined chemokines locally injected in the human skin grafts. Homing of human T cells into the human skin on SCID-hu Skin mice is a specific process since it only occurs in response to chemokine ligands that are specific for the chemokine receptors expressed on the migrating T cells. This mechanistic model allows analysis of the relevant steps involved in human T-lymphocyte migration into inflamed skin. In addition, it is successfully used for preclinical testing of drug candidates that are highly selective for human target molecules associated with the different steps of T cell migration in an environment that resembles the physiologic or pathologic conditions occurring in man.

Animals↗
PubMed2002

Skin constructs for replacement of skin tissues for in vitro testing.

Reconstructed human skin equivalents as an alternative to animal experimentation offer not only a way to concede to demands of regulatory authorities, animal welfare organizations, consumers and scientists, but also provide a means to improve and extend our knowledge on biological processes in the skin. Presently, various skin reconstructs are available composed either of the epidermal compartment only or of both the epidermal and dermal compartments. Within each compartment various types of cells can be incorporated, including keratinocytes, melanocytes and Langerhans cells in the epidermal, and fibroblasts and endothelial cells in the dermal compartment. The quality of the human skin equivalents has now reached a point that their suitability for skin toxicity testing will make great progress. Next to the field of toxicity and safety standards, skin equivalents offer a well-characterized model for studies of the basic skin biology, wound repair, regulation of melanogenesis, pathogenesis of skin diseases and skin cancer.

Biomedical Research↗
PubMed2000

Skin and laboratory tests in amoxicillin- and penicillin-induced morbilliform skin eruption.

BACKGROUND: Cutaneous amoxicillin- and penicillin-mediated reactions can be classified as immediate and delayed-type reactions. Immediate reactions are thought to involve IgE antibodies and have been studied extensively. In contrast only few data exist about delayed reactions such as morbilliform or maculopapular rash. OBJECTIVE: To assess the predictive value of immediate skin tests, skin-patch tests, specific IgE and lymphocyte transformation tests with regard to the diagnosis of delayed skin eruptions. METHODS: Skin and in vitro tests were performed in 18 subjects. Twelve subjects had penicillin- or amoxicillin-induced morbilliform exanthema and six were controls without hypersensitivity reaction, tested before and after exposure. RESULTS: Specific IgE to penicillin and immediate penicillin skin tests were negative in amoxicillin- or penicillin-induced delayed skin eruptions. In contrast, skin-patch testing and LTT were positive in 9/12 or 10/12, respectively, but negative in all six controls. CONCLUSION: These findings substantiate a T-cell-mediated immune pathomechanism in the majority of penicillin-induced delayed skin reaction. Moreover, they underline the necessity to adapt the test procedures to underlying pathomechanisms and support the diagnostic value of skin-patch testing and LTT in delayed cutaneous reactions to penicillins.

Adult↗
PubMedDate not supplied

Skin physiology of the neonate and young infant: a prospective study of functional skin parameters during early infancy.

Although neonatal and adult epidermis are similar with respect to thickness and lipid composition, skin development is not complete at birth. Previous studies indicate that the skin undergoes a process of adaptation and maturation postnatally. Postnatal skin physiology has not yet been evaluated comprehensively in a prospective study. We assessed skin function parameters prospectively in a cohort of 202 healthy term neonates (98 boys) of Caucasian descent. Measurements were performed at 3 days, 4 weeks, and 12 weeks of age and at four different body sites (frontal area, cheek, volar forearm, and gluteal surface). The following parameters were assessed: skin surface pH, corneal layer hydration (capacitance), epidermal desquamation, and surface roughness. Data were presented in box and whisker plots. Our results were as follows. Surface pH decreased by 0.3-1.1 units (p < 0.001), while desquamation increased significantly during the observation period (p < 0.001), but only on the facial areas. There was a significant increase in stratum corneum hydration (p < 0.001) which was paralleled by decreasing skin roughness, indicating smoothing of the skin surface (p < 0.001). No significant differences were found between male and female infants. These findings reflect significant cutaneous adaptation processes, particularly during the neonatal period. Reference values for functional skin parameters may be helpful in delineating normal from pathologic skin conditions such as ichthyosis or atopic dermatitis at an early stage when intervention might help to prevent exacerbations. The usefulness of these reference values will have to be evaluated in clinical practice.

Body Water↗
PubMedDate not supplied

Current trends in the use of allograft skin for patients with burns and reflections on the future of skin banking in the United States.

Cadaveric allograft skin can play a critical role in the care of patients with massive burns. It is difficult, however, to estimate current use and levels of enthusiasm for allograft skin in the United States. We report on a survey of 40 skin banks and 140 United States burn center medical directors as listed in the American Burn Association's Directory of Burn Care Resources for North America 1991-1992. Response rate was 45% for skin banks and 38% for burn directors. Overall, 12% of admitted patients were treated with allograft skin at the responding burn centers. Sixty-nine percent of burn center directors preferred to use fresh skin, although only 47% of skin banks were able to supply fresh cadaver skin. Tabulated survey results and a review and discussion of future directions in skin banking and replacement research are discussed in this paper and were presented to the Tissue Bank Special Interest group at the 1993 American Burn Association annual meeting.

Burn Units↗
PubMedDate not supplied

Storage media and temperature maintain normal anatomy of cadaveric human skin for transplantation to full-thickness skin wounds.

Cadaveric human skin provides an optimal temporary cover after early excision of full-thickness burns; however, engraftment is reduced greatly by cryopreservation. Refrigerated skin is generally preferred because of its rapid revascularization, presumably caused by its greater viability. In this study, the effects of storage solutions, temperature, and the changing of the storage media on skin graft anatomy were evaluated as an indicator of graft viability. Split-thickness human skin grafts (0.012-0.015 mm) were retrieved from cadaveric donors and grafted to circumferential, full-thickness skin wounds on athymic mice. After clinical determination of engraftment 3 months after grafting, 6-mm punch biopsy samples of the human skin were harvested and separated into two groups. Biopsy samples were stored in either saline or Eagle's minimal essential medium. Media were not changed or were changed every 3 days. All groups were stored at either 4 degrees C or room temperature (RT). After 5, 10, and 21 days of storage, biopsy samples were grafted onto athymic mice for 20 days. The biopsy grafts were then collected and prepared for histologic scoring on a scale of +4 (normal anatomy) to 0 (no epithelial cells). Significant differences in histologic scores were found by the nonparametric Kruskal-Wallis test followed by Wilcoxon pairwise comparison. Skin stored in media maintained better histologic anatomy than skin in saline, suggesting better maintenance of viability. There was also better preservation of anatomy after storage at RT for 21 days with media changes every 3 days when compared to unchanged media and all conditions at 4 degrees C. These results support the hypothesis that increased availability of nutrients and increased storage temperature maintain higher viability of cadaveric human skin for transplantation to full-thickness cutaneous wounds.

Animals↗
PubMed2002

Skin colour and skin cancer - MC1R, the genetic link.

Pigmentary traits such as red hair, fair skin, lack of tanning ability and propensity to freckle (the RHC phenotype) have been identified as genetic risk factors for both melanoma and non-melanocytic skin cancers when combined with the environmental risk factor of high ultraviolet light exposure. The human melanocortin-1 receptor (MC1R) is a key determinant of the pigmentation process and can account in large part for the diverse range of variation in human pigmentation phenotypes and skin phototypes. The coding sequence is highly polymorphic in human populations, with several of these variant forms of the receptor now known to be associated with the RHC phenotype. We have examined variant allele frequencies in the general population and in a collection of adolescent dizygotic and monozygotic twins with defined pigmentation characteristics. Variant allele frequencies have also been determined in several case-control studies of sporadic melanoma, basal cell carcinoma and squamous cell carcinoma, and in familial melanoma kindreds collected within Australia. These studies have shown that three RHC alleles - Arg151Cys, Arg160Trp and Asp294His - were associated with increased risk in all forms of skin cancer and with penetrance and age of onset in familial melanoma in mutation carriers. There is a significant RHC allele heterozygote carrier effect on skin phototype and skin cancer risk, which indicates that variant alleles do not behave in a strictly recessive manner. Ultimately, the genetic and chemical assessment of melanin synthesis rather than skin colour will be the best indicator for skin cancer risk, and such genetic association studies combined with functional analysis of variant alleles should provide the link to understanding skin phototypes.

Alleles↗
PubMed2004

Skin nitric oxide and its metabolites are increased in nonburned skin after thermal injuries.

Local and systemic inflammation can lead to progression of burn wounds, converting second- to third-degree wounds or extending the burn to adjacent areas. Previous studies have suggested that the skin is an important site of production of nitric oxide (NO), synthesized by inducible nitric oxide synthase (iNOS) activation after injury. NO increases in burned wounds, but its formation in noninjured skin has not been investigated. We hypothesized that after severe burns, NO and cytotoxic peroxynitrite would increase in noninjured skin. We also tested the hypothesis that BBS-2, a specific inhibitor of iNOS, would impair NO formation after burn. Thirteen female sheep were randomized into burn injury and smoke inhalation (n = 5, group 1), burn and smoke treated with BBS-2 (n = 3, group 2), and sham (saline treatment, no injury) (n = 5, group 3). All the animals, including the sham-injury group, were mechanically ventilated for 48 h. Samples of nonburned skin and plasma were collected from each animal, and levels of NO and its metabolites were evaluated using a NO chemiluminescent detector. Nitrotyrosine and iNOS expression were determined in the skin by Immunoperoxidase staining, and scoring of masked slides (epidermis, hair follicles, vessels, glands, and stroma) was performed. Skin NO and metabolites significantly increased in the burn and smoke injury group, and this was inhibited by BBS-2. Nitrotyrosine expression also increased significantly in the skin of burned animals. BBS-2 prevented the increase of NOx but not the increase of nitrotyrosine expression in skin. Plasma levels of NO increased in burned animals when compared with sham, but this increase was not significant. The increase of NO and its metabolites after burn in noninjured skin is followed by a significant increase in peroxynitrite, a potent cytotoxic mediator.

Animals↗
PubMed2005

Localization of haptoglobin in normal human skin and some skin diseases.

BACKGROUND: Haptoglobin (Hp) is an acute-phase reactant, known to be produced mainly in the liver. Haptoglobin can also be detected in the cytoplasm of normal epidermal Langerhans cells (LCs), and can prevent their functional maturation. The synthesis of Hp in skin cells has not been well studied. METHODS: We examined Hp expression at mRNA and protein levels by in situ hybridization and immunohistochemistry, respectively, in normal human skin and in the skin of patients with psoriasis, lichen planus, erythroderma, seborrheic keratosis, verruca vulgaris, basal cell carcinoma, systemic lupus erythematosus, pemphigus and bullous pemphigoid. RESULTS: (1) Haptoglobin mRNA was expressed in the epidermal keratinocytes (KCs), the epithelial cells of hair follicles, sebaceous glands and eccrine glands in normal skin and all dermatoses investigated. (2) Whereas compared with normal skin, the Hp mRNA in KCs of patients with psoriasis, lichen planus, erythroderma, seborrhoea keratosis and verruca vulgaris was significantly intensified, it was weaker in patients with systemic lupus erythematosus, pemphigus and bullous pemphigoid. (3) Haptoglobin protein only stained positively in some KCs of patients with psoriasis, lichen planus and erythroderma. (4) Although some but not all epidermal LCs were positively stained with anti-Hp antibody in normal skin and in skin samples from all patients, the ratios of Hp-positive LCs/total LCs were significantly higher in those diseases with intensified Hp mRNA in KCs. CONCLUSIONS: Skin is another extrahepatic organ where Hp can be synthesized by KCs. The expression of Hp mRNA in KCs and the Hp protein in both LCs and KCs appears to be correlated with the amount of inflammation, which might indicate that skin itself is involved in down-regulating the local inflammatory reaction by KC-synthesized Hp.

Haptoglobins↗
PubMedDate not supplied

Characteristics of skin wrinkling and dermal changes induced by repeated application of squalene monohydroperoxide to hairless mouse skin.

We have studied the effect of squalene monohydroperoxides (Sq-OOH), initial products of UV-peroxidated squalene, on the skin of hairless mice. Repeated topical application of 10 mM Sq-OOH to hairless mice for 15 weeks induced definite skin wrinkling. When image analysis was used to compare wrinkle formation induced by ultraviolet B (UVB) irradiation and Sq-OOH treatment, the degree of wrinkling in exposed skin was seen to be similar. However, the characteristics of wrinkles induced by either method differed markedly with regard to direction and distribution. Biochemical analysis revealed a significant decrease in collagen content per unit area and mass in Sq-OOH-treated skin, whereas no changes per unit area and decrease in collagen per unit mass were observed in UVB-irradiated skin. As for glycosaminoglycan (GAG) content per unit area, significant increases were observed in both Sq-OOH-treated skin and UVB-irradiated skin. These changes were not induced by organic hydroperoxides such as TERT-butylhydroperoxide or cumene hydroperoxide treatment. Histological observation revealed epidermal hyperplasia and dermal alterations such as collagen degradation and GAG increases in Sq-OOH-treated skin. Histological changes induced by Sq-OOH were not as pronounced as those induced by UVB irradiation. These results clearly suggest that the wrinkling and changes in dermal collagen content induced by Sq-OOH are qualitatively different to those induced by UVB exposure. This may provide a useful model for the study of skin aging, particularly with regard to collagen content.

Administration, Topical↗
PubMed2001

The regulation of skin proliferation and differentiation in the IR null mouse: implications for skin complications of diabetes.

Impaired wound healing of skin is one of the most serious complications of diabetes. However, the pathogenesis of this process is not known, and it is unclear whether impaired insulin signaling could directly affect skin physiology. To elucidate the role of insulin in skin, we studied skin insulin receptor (IR) null mice. The morphology of the skin of newborn IR null mice was normal; however, these mice exhibited decreased proliferation of skin keratinocytes and changes in expression of skin differentiation markers. Due to the short life span of the IR null mice, further characterization was performed in cultured skin keratinocytes that can be induced to differentiate in vitro, closely following the maturation pattern of epidermis in vivo. It was found that despite a compensatory increase in the insulin-like growth factor I receptor autophosphorylation, differentiation of cultured IR null keratinocytes was markedly impaired. In vitro proliferation was not affected as much. Furthermore, although the basal glucose transport system of the null mice was not defective, the insulin-induced increase in glucose transport was abrogated. These results suggest that insulin regulates, via the IR, the differentiation and glucose transport of skin keratinocytes, whereas proliferation is affected by the diabetes milieu of IR knockout mice.

Animals↗
PubMed2006

Skin penetration flux and lag-time of steroids across hydrated and dehydrated human skin in vitro.

To study the effect of hydration on skin absorption, we investigated penetration across human skin of twelve model chemicals having steroidal structure but different molecular weight and compared the steady-state penetration rate (J) and lag-time (t) across hydration intact skin (Jh and th) with that across dehydrated intact skin (Jd and td). Stratum corneum (SC) thickness of hydrated (52 microm) is 3.3 times that of dehydrated skin (16 microm). Transepidermal water loss (TEWL) of hydrated (7.6+/-2.1 g/m2/h) is twice that of dehydrated skin (3.4+/-1.6 g/m2/h, p<0.05) which are similar to in vivo values, suggesting the SC barrier function was recovered. The ratio of Jh/Jd ranged between 0.7 and 3.6 (average of 1.9). On the other hand, the ratio of th/td was almost constant (average of 0.8). Ratios of Jh/Jd and th/td were independent of MW and Ko/w. In percutaneous absorption experiments in vitro, skin was preserved in culture medium until use and SC might swell during that time. Therefore, we consider the possibility that J and t varied between hydrated and dehydrated skin. We confirmed the difference of J and t between hydrated and dehydrated skin in vitro and now need to define these results under in vivo condition.

Adult↗
PubMed2004

Newly explored electrical properties of normal skin and special skin sites.

Skin impedance measurements at various skin sites yield different impedance loci for normal skin and special skin sites. The results of skin impedance measurements taken at such sites with a two-electrode measurement system are presented herein. Some of these sites can be identified as acupuncture points. Data from 4 volunteers were acquired by means of a data acquisition board and a measuring system consisting of the measurement circuit, including several electrode types, and a power supply. The Cole model is a model for an equivalent electrical circuit of the skin-electrode system. The system was used to derive skin-typical parameters from the Bode plot of the whole system. These parameters are the fractional power a, the pseudo-capacity K, the parallel resistance Rp, and the serial resistance Rs of the equivalent electrical circuit. The results show that the measured parameters differ between normal skin and special skin sites. These effects have not previously been discovered by other authors, since there has been no systematic investigation of many acupuncture points to date, and there has been no apparent need for such an investigation. A number of necessary criteria for acupuncture point detection can be derived from the results obtained.

Acupuncture↗
PubMed1999

Sun exposure, skin cancers and related skin conditions.

Skin cancer is the most commonly occurring cancer in humans. Solar keratoses are related benign tumours that are at least ten times commoner than skin cancers and photoageing of the skin is still more common. Descriptive studies show that incidence rates of the main types of skin cancer, basal cell carcinoma, squamous cell carcinoma and melanoma are maximal in populations in which ambient sun exposure is high and skin (epidermal) transmission of solar radiation is high, suggesting strong associations with sun exposure. Analytic epidemiological studies confirm that exposure to the UV component of sunlight is the major environmental determinant of skin cancers and associated skin conditions and evidence of a causal association between cumulative sun exposure and SCC, solar keratoses and photodamage is relatively straightforward. Results for BCC and melanoma are complicated by several factors including the existence of subgroups of these diseases which do not appear to be caused by sun exposure yet have been included in most aetiological studies to date. Complementary to epidemiological data is the molecular evidence of ultraviolet (UV) mechanisms of carcinogenesis such as UV-specific mutations in the DNA of tumour suppressor genes in skin tumours. With increased UV irradiation resulting from thinning of the ozone layer, skin cancer incidence rates have been predicted to increase in the future--unless, as is hoped, human behaviour to reduce sun exposure can offset these predicted rises.

Australia↗
PubMed1999

Sun and skin. Role of phototype and skin colour.

The study of the biological effects of sun on the skin is one of the most topical questions in the recent dermatological literature. Interest in these effects has grown since it was demonstrated that the sun accelerates intrinsic skin ageing and is a principal factor for skin cancer. Skin damage caused by the sun is mainly due to UV radiation. Skin damage certainly has ancient roots, but has undergone sudden changes since man began to migrate to different geographical areas, for example when northern European populations colonised sunny areas close to equator. It is not a coincidence that the highest incidence of sun induced neoplasias is observed among white population of Australia. This epidemiological finding focused the interest towards the identification of phenotypic factors conditioning skin response to sunlight, and hence towards the definition of the so called phototype. After the fundamental work of Fitzpatrick based on sun exposure history more recent studies have shown that skin response to UV-rays can be predicted, to a good approximation, by skin colorimetry. Therefore this simple, cheap and non invasive measurement enables to predict sun reactivity skin type and to evaluate the melanoma risk.

Colorimetry↗
PubMed1977

Multiple granulocytic tumors of the skin: report of six cases of myelogenous leukemia with initial manifestations in the skin.

The clinical and pathologic findings in six patients with myelogenous leukemia presenting initially as multiple granulocytic tumors of the skin were reviewed. The skin of the trunk was most commonly involved with multiple, confluent erythematous plaques and soft, tender, non-ulcerated, violaceous nodules. Two patients had been treated for malignant lymphoma eight and nine years prior to the onset of skin lesions (Hodgkin's disease and nodular lymphocytic lymphoma, respectively), and cutaneous granulocytic leukemia developed in sites of irradiated skin. The skin biopsies in all cases were originally misinterpreted by the pathologist as malignant lymphoma and the correct diagnosis of granulocytic leukemia was not established in any of the cases until overt extracutaneous involvement was detected. The interval in the six patients from skin biopsy to definite involvement of blood and bone marrow by acute granulocytic leukemia ranged from three weeks to six months with a mean interval of 3.8 months. The mean duration of survival from the diagnosis of extracutaneous dissemination was 12.7 months (range of three months to two and one-half years). Poorly differentiated myelogenous leukemia was demonstrated at postmortem examination in all cases. Cytochemical stains of formalin-fixed, paraffin-embedded tissues confirmed the granulocytic origin of the neoplasm: leukemic cells in skin biopsies, bone marrow aspirates, and autopsy specimens contained abundant naphthol AS-D chloracetate esterase. The findings indicate that granulocytic leukemia may rarely present with skin tumors as the original manifestation of the disease. Recognition of the distinctive clinical, histopathologic, and enzyme histochemical features of the lesion provide a basis for distinguishing granulocytic sarcoma of the skin from mycosis fungoides and other cutaneous malignant lymphomas.

Acetates↗