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At least 109 records · Page 6Linked to original sources
PubMed1996

Evaluation of human skin reconstituted from composite grafts of cultured keratinocytes and human acellular dermis transplanted to athymic mice.

This study evaluates the use of composite grafts of cultured human keratinocytes and de-epidermalized, acellular human dermis to close full-thickness wounds in athymic mice. Grafts were transplanted onto athymic mice and studied up to 8 wk. Graft take was excellent, with no instances of infection or graft loss. By 1 wk, the human keratinocytes had formed a stratified epidermis that was fused with mouse epithelium, and by 8 wk the grafts resembled human skin and could be freely moved over the mouse dorsum. Immunostaining for keratins 10 and 16 and for involucrin revealed an initial pattern of epithelial immaturity, which by 8 wk had normalized to that of mature unwounded epithelium. Mouse fibroblasts began to infiltrate the acellular dermis as early as 1 wk. By 8 wk fibroblasts had completely repopulated the dermis, and blood vessels were evident in the most superficial papillary projections. Dermal elements, such as rete ridges and elastin fibers, which were present in the starting dermis, persisted for the duration of the experiment. Grafts using keratinocytes from dark-skinned donors as opposed to light-skin donors had foci of pigmentation as early as 1 wk that progressed to homogenous pigmentation of the graft by 6 wk. These results indicate that melanocytes that persist in vitro are able to resume normal function in vivo. Our study demonstrates that composite grafts of cultured keratinocytes combined with acellular dermis are a useful approach for the closure of full-thickness wounds.

Animals↗
PubMed1980

The ultrastructure of collagen in the dermis of tight-skin (Tsk) mutant mice.

A recently discovered dominant mutation in C57/B10 mice called tight-skin (Tsk) results in hypertrophy of certain collagenous tissues including the dermis and hypodermis. The skin of heterozygotes (Tsk/+) is indurated and substantially stiffer than that of the normal animals (+/+). In this study, an electron microscopical comparison of the skin of these animals revealed that the fibrous architecture of the hypertrophic reticular dermis of Tsk/+ mice is more disorganized than that of the +/+ mice and in many areas, the collagen fibrils are more densely packed. The abundance of fibroblasts with distended endoplasmic reticulum in both the dermis and hypodermis of Tsk/+ mice is consistent with increased collagen synthesis. Several of the changes in the dermis and hypodermis of the Tsk/+ mice are similar to changes reported in sclerodermatous skin of man. Surprisingly, an apparent abnormality in the morphology of some of collagen fibrils in the skin of Tsk/+ mice was found to be at least as prevalent in the "normal" +/+ mice. The reticular dermis of both animals contain scattered fibrils which are much larger in diameter than normal and often have a twisted appearance resulting from either helical grooves in the surface of the fibril or discrete branches which twist about one another.

Animals↗
PubMed1992

Immunohistochemical study of basement membrane reconstruction by an epidermis-dermis recombination experiment using cultured chick embryonic skin: induction of tenascin.

The production of extracellular matrix components such as laminin, Type IV collagen, fibronectin, and tenascin during the formation of basement membrane in cultured epidermis-dermis recombinant skin of 13-day-old chick embryo was analyzed immunohistochemically. The epidermis and dermis were separated from each other by treatment with EDTA and/or dispase. The basal lamina of the basement membrane was thus removed from both epidermis and dermis. The isolated epidermis was overlaid onto the isolated dermis, i.e., recombined, and then cultured for 1-7 days in a chemically defined medium (BGJb) on a Millipore filter. Immunofluorescence labeling was used for light microscopy and HRP or colloidal gold labeling for electron microscopy. In specimens from 2-day cultures, positive sites of anti-laminin and anti-fibronectin reaction were observed light microscopically as patches which, at the electron microscopic level, corresponded to fragments of the basal lamina located immediately beneath and in the vicinity of the attachment plaques of the hemidesmosomes. The staining pattern became continuous 7 days after recombination. Fluorescence labeling of laminin and fibronectin appeared somewhat earlier than that of Type IV collagen and tenascin. All of the four components were found localized primarily in the basal lamina. Furthermore, fibronectin and tenascin were also distributed in the extracellular matrix of the dermis. The expression of tenascin, which does not exist in the basement membrane of 13-day-old intact embryonic skin, was induced in vitro. These results suggest that hemidesmosomes may play an important role in the reconstruction of the basement membrane and that various components of the basement membrane appeared at different times during the reconstruction.

Animals↗
PubMed1990

Cellular elements of the dermis and collagen remodelling during larval life of anurans.

The differentiation of the collagenous dermis has been followed by electron microscopy in larvae of three anuran species. Events can be divided into five phases, depending on the organization of the cellular elements. Initial secretion of collagen appears to be from the epidermis but fibroblasts are present from early stages. Apart from secretion, there is phagocytosis of fibrils by fibroblasts, seen most frequently when the operculum is formed and at metamorphosis. In most larval stages, the dermis consists of regular plies of collagen fibrils, penetrated by processes from underlying fibroblasts and crossed by nerves, with a cellular layer defining the deep face. In Rana, these cells contain enormous vacuoles and have been called "compartmented cells", but the vacuoles are absent in Bufo and Xenopus. Just before metamorphosis, fibroblasts and chromatophores migrate into the dermis, and establish a stratum laxum. A few plies of larval collagen fibrils are left under the epidermis, the bulk of the larval dermis becomes the stratum compactum. During larval life, the hypodermis contains chromatophores, blood capillaries and wandering leucocytes. The dermis gains a blood circulation only at metamorphosis, when subdermal lymph sacs and vertical smooth muscles are established.

Animals↗
PubMed1989

Biochemical, morphological and stereological study of the dermis in three members of a large family with type IV Ehlers-Danlos syndrome.

Biochemical, morphological and stereological studies were carried out on dermal biopsies obtained from three members of a large family with a positive clinical history of type IV Ehlers-Danlos syndrome. Ultrastructural analysis showed that fibroblasts from two affected individuals presented abnormally dilated rough endoplasmic reticulum cisternae engorged by microfilamentous material. When cultured, fibroblasts from two affected individuals synthesized and secreted normal amounts of type I procollagen, but only a very low percentage of type III procollagen was secreted. Cellular retention of type III procollagen was confirmed by immunofluorescence. Also the secretion of fibronectin appeared delayed. Stereological analysis carried out on semithin sections of dermis by the point counting method showed that the relative volume of collagen fibers was decreased in the reticular dermis and the relative volume of elastin fibers was increased mainly in the upper layer of reticular dermis, in comparison to normal controls (P less than 0.01). Collagen fiber sizes were significantly (P less than 0.01) reduced in all dermis layers. No alterations were seen in the dermis and in cultured fibroblasts from the clinically normal individual.

Adolescent↗
PubMed1992

Changes in the ventral dermis and development of iridophores in the anadromous sea lamprey, Petromyzon marinus, during metamorphosis: an ultrastructural study.

The ultrastructural changes that take place in the ventral dermis along with the development of iridophores were examined in the anadromous sea lamprey, Petromyzon marinus, during metamorphosis. There is a disruption of all components of the ventral dermis and a reformation that results in a structure very similar to that prior to metamorphosis. Although not a dermal component, a layer of iridophores develops directly beneath the dermis during late metamorphosis. The dermal endothelium is lost by mid metamorphosis (stage 4) and the highly organized collagenous lamellae making up the bulk of the dermis become disrupted by the migration of fibroblasts into the region. Many of these fibroblasts are involved in the degradation of the lamellae. By stage 5 of metamorphosis some fibroblasts become highly active collagen synthesizing cuboidal shaped cells that align to form a layer above the reformed dermal endothelium. New lamellae are formed by these cuboidal cells which then divide and migrate into the lamellae where they assume the characteristic attenuated appearance of fibroblasts in the adult dermal lamellae region. Iridophores first appear during stage 5 directly beneath the dermal endothelium. Reflecting platelets develop from double membraned vesicles associated with the Golgi apparatus. By late metamorphosis, stacks of trapezoidal shaped platelets fill the cytoplasm of the iridophores. The significance of the changes in the dermis during metamorphosis are discussed. This work is part of a continuing series of studies on the connective tissues in the anadromous sea lamprey.

Animals↗
PubMed1982

Transplantation of the reversed dermis from skin leading to repair of the buccal mucosal epithelium.

Skin grafting or mucosal grafting has been widely applied as the established method to compensate mucosal defects. However, in the grafted skin the epidermis never transformed into the mucosal epithelium; the original nature of the transplant was maintained as skin. The available donor of mucosa is also strictly limited. Therefore, an improvement in method has been much needed in the field of oral surgery. We tried to transplant the dermis freed completely from the epidermis instead of the full-thickness skin, and succeeded in compensation of the mucosal defect. The defects of the buccal mucosa in 30 dogs were repaired, one side with reversed dermis graft (RDG) in which the dermis was turned inside out and sutured onto the bed. On the other side, the ordinary free full-thickness skin graft (FTSG) was carried out as a control. Comparative clinical and histological observations were conducted to analyze the healing processes. In RDG the graft was covered by the surrounding mucosal epithelium to form the mucosal tissue, while the implanted tissue inhibited the wound constricture. Histological examination revealed that the epithelial elements underwent degeneration, presumably through being embedded by the grafting of the dermis inside out. The epithelium covering the dermis graft seems to be nothing but normal oral mucosal epithelium.

Animals↗
PubMed1994

Modifications of the dermis during scale regeneration in the lizard tail.

During scale morphogenesis in the regenerating tail of lizards (Anolis and Lampropholis) the structure of the dermis undergoes changes in relation to the ingrowth of epidermal papillae to form the new scales. Cell proliferation in the dermis, as revealed by the uptake of 3H-thymidine, is high in the prescaling region of the regenerating tail but lower than the proliferation in the epidermis. Under the epidermis of the scaling region dermal cell proliferation rapidly drops down under the distal (apical) and proximal (caudal) sides of the infolding epidermal papillae. Dermal fibroblasts take up 3H-proline in high amounts, especially in the forming deep dermal layer, where many collagen fibrils are laid down forming dense connective. Electron microscopic study revealed that "anchoring filaments" link the basement membrane of the epidermis with the deep dermis, in particular in the sinking hinge region. As a result of the higher proliferation of the epidermis with respect to the dermis (heterochrony) and the presence of dermo-epithelial "anchoring filaments", the superficial laminar epidermis sinks into the dermis to produce new scales. The epidermal downpushing is evidenced by a characteristic distortion of the dermal fibrils under the distal and the proximal sides, and in the hinge region of the forming scales.

Animals↗
PubMed2005

Fluconazole distribution in rat dermis following intravenous and topical application: a microdialysis study.

The objective of this study was to investigate the skin distribution of fluconazole, a water-soluble antifungal agent, following intravenous (i.v.) and topical administration in the awake freely moving rat. Following i.v. bolus injection of fluconazole (10 mg/kg), a dual-site microdialysis sampling was performed in jugular vein and dermis in five rats. In addition, cutaneous absorption was studied by dermal microdialysis sampling following topical application of Diflucan Gel 0.5% to 12 rats. Fluconazole microdialysate concentrations were measured by on-line HPLC. To calibrate in vivo the probes, a fluorinated analog (UK-54737) of fluconazole was used as retrodialysis marker after demonstrating that recoveries were no different. Following i.v. bolus injection, fluconazole rapidly penetrates into the dermis. Cutaneous microdialysis sampling provided dermal concentrations of fluconazole, which were very similar to the unbound plasma concentrations determined by vascular microdialysis. The distribution equilibrium was rapidly achieved with a dermis-to-plasma partition coefficient of 1.02+/-0.04 (n=5). Following topical application of 0.5 g of Diflucan Gel containing 0.5% of fluconazole, active unbound concentrations in dermis were measured by cutaneous microdialysis for 11 h after application. The area under the curve (AUC) of fluconazole in dermal dialysate was relatively constant to an implantation depth of approximately 350 microm. Below this depth, the AUC progressively decreased with increasing implantation depth of the probe. Finally, this study shows that cutaneous microdialysis is an effective and minimally invasive tool to evaluate the dermal pharmacokinetics of fluconazole following intravenous or topical administration.

Administration, Topical↗
PubMed2006

[The reversed dermis flap soon to be forgotten as a major filler?].

In his paper entitled "The reversed dermis flap" published in 1978, Pakiam explained the advantages of de-epithelialising local flaps and applying them dermis-side down. We present a ten-year series of 107-reversed dermis flaps used to raise depressed scars. There have been no significant complications in this series except two cases of infection and six cases of postoperative haematoma. All patients were satisfied with the cosmetic outcome. We do not use this flap as much as we used to since Coleman demonstrated how efficient lipostructure could be especially when applied to thin depressed scars. The reversed dermis flap remains invaluable in cases of widespread scars or when lipostructure is dangerous or impossible.

Dermis↗
PubMed2005

Nerve fibre and sensory end organ density in the epidermis and papillary dermis of the human hand.

Quantification of sensory recovery after peripheral nerve surgery is difficult and no accurate techniques are available at present. Quantification of reinnervated skin has been used experimentally, and in some clinical studies, but the lack of knowledge about the normal sensory distribution has been a problem. The purpose of this study was, therefore, to map the density of sensory end organs, nerve fibres and free nerve endings in the glabrous skin of the human hand. Skin biopsies were taken from patients undergoing acute and elective hand surgery. Nerve fibres were stained in the epidermis and papillary dermis and quantified in five sites on the palm of the hand, using protein gene product 9.5 immunoreactivity-a panneuronal marker. The finger tip skin was found to have more than twice the nerve fibre density in the papillary dermis than the skin of the palm, and the number of Meissner corpuscles in the finger tip was also higher than in the palm. We found a reduction in innervation density with increasing age in the dermis, however, that was not the case for the epidermis. The innervation of the epidermis showed high interindividual variability and unlike the papillary dermis did not display any pattern of distribution in the hand.

Adult↗
PubMed2001

The effect of mechanical forces (vibration or external compression) on the dermal water content of the upper dermis and epidermis, assessed by high frequency ultrasound.

An ultrasound scanner, is used to detect changes in water content of the upper dermis. This has previously been found to vary with age and to show diurnal variation. Furthermore, oedema due to venous disease can be shown, using this technique, to respond to elevation. In this study, the water content of the upper dermis and epidermis of the leg in 16 subjects is increased following vibration for 10 minutes using a passive exercise system. A study of pressure applied to the skin of the heel for 10 minutes in 14 volunteers also showed an increase in water content of epidermis and dermis in young persons, but less so in the elderly. It is postulated that the anatomical structure of the vascular bed of the upper dermis predisposes to transsudation when pressure to the skin is applied, thereby maintaining the resilience of the skin in the young, but less so in the elderly.

Adult↗
PubMed2001

Aging- and photoaging-dependent changes of enzymic and nonenzymic antioxidants in the epidermis and dermis of human skin in vivo.

This is a comprehensive study of the changes in major antioxidant enzymes and antioxidant molecules during intrinsic aging and photoaging processes in the epidermis and dermis of human skin in vivo. We show that the activities of superoxide dismutase and glutathione peroxidase are not changed during these processes in human skin in vivo. Interestingly, the activity of catalase was significantly increased in the epidermis of photoaged (163%) and naturally aged (118%) skin (n = 9), but it was significantly lower in the dermis of photoaged (67% of the young skin level) and naturally aged (55%) skin compared with young (n = 7) skin. The activity of glutathione reductase was significantly higher (121%) in naturally aged epidermis. The concentration of alpha-tocopherol was significantly lower in the epidermis of photoaged (56% of young skin level) and aged (61%) skin, but this was not found to be the case in the dermis. Ascorbic acid levels were lower in both epidermis (69% and 61%) and dermis (63% and 70%) of photoaged and naturally aged skin, respectively. Gluta thione concentrations were also lower. Uric acid did not show any significant changes. Our results suggest that the components of the antioxidant defense system in human skin are probably regulated in a complex manner during the intrinsic aging and photoaging processes.

Adult↗
PubMed2003

SPARC-null mice display abnormalities in the dermis characterized by decreased collagen fibril diameter and reduced tensile strength.

Although collagen and elastic fibers are among the major structural constituents responsible for the mechanical properties of skin, proteins that associate with these components are also important for directing formation and maintaining the stability of these fibers. We present evidence that SPARC (secreted protein acidic and rich in cysteine) contributes to collagen fibril formation in the dermis. The skin of SPARC-null adult mice had approximately half the tensile strength as that of wild-type skin. Moreover, the collagen content of SPARC-null skin, as measured by hydroxyproline analysis, was substantially reduced in adult mice. At 2 weeks of age, no differences in collagen content were observed; within 2 months, however, the dermis of SPARC-null mice displayed a reduced collagen content that persisted through adulthood until approximately 20 months, when collagen levels of SPARC-null skin approximated those of wild-type controls. The collagen fibrils present in SPARC-null skin were smaller and more uniform in diameter, in comparison with those of wild-type skin. At 5 months of age, the average fibril diameter in SPARC-null versus wild-type skin was 60.2 nm versus 87.9 nm, respectively. Extraction of soluble dermal collagen revealed a relative increase in collagen VI, accompanied by a decrease in collagen I, in SPARC-null mice. A reduction in the relative amounts of higher-molecular weight collagen complexes was also observed in extracts of dermis from SPARC-null animals. Thus the absence of SPARC compromises the mechanical properties of the dermis, an effect that we attribute, at least in part, to the changes in the structure and composition of its collagenous extracellular matrix.

Acetic Acid↗
PubMed1998

Effect of temperature on the optical properties of ex vivo human dermis and subdermis.

The effect of temperature on the optical properties of human dermis and subdermis as a function of near-infrared wavelength has been studied between 25 degrees C and 40 degrees C. Measurements were performed ex vivo on a total of nine skin samples taken from the abdomen of three individuals. The results show a reproducible effect of temperature on the transport scattering coefficient of dermis and subdermis. The relative change of the transport scattering coefficient showed an increase for dermis ((4.7+/-0.5) x 10(-3) degrees C(-1)) and a decrease for subdermis ((-1.4+/-0.28) x 10(-3) degrees C(-1)). Note that the magnitude of the temperature coefficient of scattering was greater for dermis than subdermis. A reproducible effect of temperature on the absorption coefficient could not be found within experimental errors. System reproducibility in transport scattering coefficient with repeated removal and repositioning of the same tissue sample at the same temperature was excellent at +/-0.35% for all measurements. This reproducibility enabled such small changes in scattering coefficient to be detected.

Biophysical Phenomena↗
PubMed2001

Optical properties of porcine skin dermis between 900 nm and 1500 nm.

The weak absorption of shortwave infrared light by skin tissues between 700 and 1500 nm offers an important window for diagnosis by optical means. The strong scattering of shortwave infrared light by the skin, however, presents a challenge to the modelling of light propagation through the skin and the understanding of skin optics. We have measured the collimated and diffuse transmittance and diffuse reflectance of porcine skin dermis samples within 30 h post-mortem. Monte Carlo simulations have been performed to inversely determine the absorption coefficient, scattering coefficient and anisotropy factor of the dermis samples in the spectral range from 900 to 1500 nm. We further analyse the sensitivity of the values of the parameters to the experimental errors and inverse calculation procedures. The state of the cellular integrity of the skin samples following optical measurements was verified using transmission electron microscopy. These results were correlated to study post-mortem effects on the in vitro optical properties of porcine dermis. We concluded that for samples stored within crushed ice for up to 30 h post-mortem the wavelength dependence of optical properties of the dermis remains unchanged while the values of the parameters vary moderately due to modification of the water content of the tissue.

Animals↗
PubMed2000

Application of artificial dermis graft to correct a depression after tissue resection.

The authors present 7 cases of artificial dermis implantation to correct a depression after tissue resection. Four of the seven cases resulted from resection of a malignant tumor (N = 3) and from a benign subcutaneous tumor (N = 1). The other 3 cases were the result of temporal muscle harvest to reconstruct facial palsy. In 1 patient a mild degree of bone deformity also existed. The pieces of artificial dermis employed varied from 35 x 40 to 40 x 80 mm in size. In 5 patients two sheets were implanted, and in 2 patients three sheets were implanted. In 2 patients the dermis sheets were covered by a pedicled temporal fascial flap with a free split-thickness skin graft because whole skin was resected as a result of a malignant skin tumor. There was no postoperative infection or allergic reaction in any of the patients. In all cases there was no postoperative contracture, and the implanted area was soft. An adequate or acceptable thickness of subcutaneous tissue was obtained. Artificial dermis may be a useful option as implantation material to correct a depression after tissue resection, especially for wide and comparatively shallow depressions.

Aged↗
PubMed2001

The dermis-prelaminated scapula flap for reconstructions of the hard palate and the alveolar ridge: a clinical and histologic evaluation.

Ideal reconstructions of complex defects in the midface require the restitution not only of bone and soft tissue, but also of a thin and durable lining of the oral cavity. So far, split-thickness skin grafts, intestinal grafts, and in vitro cultured mucosal grafts have been used for the reconstruction of the oral lining. The use of skin as a substitute for oral mucosa is controversial because contraction, hair growth, maceration, and dysplastic changes can occur. This clinical and histologic study was performed to evaluate the suitability of dermis as a substitute for oral lining. Twelve complex defects of the midface were reconstructed with dermis-prelaminated scapula flaps. A bony flap from the lateral border of the scapula was prepared, and osseointegrated implants were placed. The bone flap was then prelaminated with dermis and covered with a Gore-Tex membrane to prevent adhesions. The composite flap was transferred to the midface 2 to 3 months later. The oral lining of the flap was evaluated clinically and histologically at 2, 4, and 6 weeks and at 3 to 41 months after the reconstruction. In all patients, the reconstructed bone was covered with a thin and lubricated surface without hair growth. None of the patients showed any signs of maceration. Histologically, these findings corresponded to a keratinized stratified squamous epithelium with highly developed connective-tissue papillae. These features closely resemble those of the normal mucosa of the hard palate and the gingiva. Thus, dermis prelamination is an effective method for reconstructing the mucosa of the alveolar ridge and the hard palate.

Adolescent↗