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Mice with a null mutation of the TGF alpha gene have abnormal skin architecture, wavy hair, and curly whiskers and often develop corneal inflammation.

Mice homozygous for a disrupted transforming growth factor alpha (TGF alpha) gene are healthy and fertile, although some older mice show evidence of corneal inflammation. In contrast with TGF alpha +/- and +/+ animals, TGF alpha -/- mice have a pronounced waviness of the coat. Histological examination of the skin from TGF alpha -/- mice reveals a dramatic derangement of hair follicles. Mice with a disrupted TGF alpha gene also have curly whiskers, first evident on the day of birth. The phenotype of TGF alpha -/- mice is remarkably similar to that of the mouse mutant waved-1 (wa-1). Offspring resulting from crosses between TGF alpha -/- and wa-1 mice display the curly whisker-coat phenotype, indicating that the basis of the wa-1 phenotype is a mutation in the TGF alpha gene. These observations suggest that TGF alpha plays a pivotal role in determining skin architecture and in regulating hair development.

Animals↗

Skin abnormalities generated by temporally controlled RXRalpha mutations in mouse epidermis.

Nuclear receptors for retinoids (RARs) and vitamin D (VDR), and for some other ligands (TRs, PPARs and LXRs), maybe critical in the development and homeostasis of mammalian epidermis. It is believed that these receptors form heterodimers with retinoid X receptors (RXRs) to act as transcriptional regulators. However, most genetic approaches aimed at establishing their physiological functions in the skin have been inconclusive owing either to pleiotropic effects and redundancies between receptor isotypes in gene knockouts, or to equivocal interpretation of dominant-negative mutant studies in transgenic mice. Moreover, knockout of RXRalpha, the main skin RXR isotype, is lethal in utero before skin formation. Here we have resolved these problems by developing an efficient technique to create spatiotemporally controlled somatic mutations in the mouse. We used tamoxifen-inducible Cre-ER(T) recombinases to ablate RXRalpha selectively in adult mouse keratinocytes. We show that RXRalpha has key roles in hair cycling, probably through RXR/VDR heterodimers, and in epidermal keratinocyte proliferation and differentiation.

Alleles↗

Abnormal skin development in pupoid foetus (pf/pf) mutant mice.

At 13 days of development the epidermis of mice homozygous for the pupoid foetus (pf/pf) mutation varies in thickness between one and ten cell layers. By 16 days of development cells from the dermis have invaded the epidermis and may be found throughout the epidermis and on its surface. Among these cells are nerve fibres and Schwann cells as well as other unidentified cells. Antibodies directed against fibronectin bind to these abnormal groups of cells in the mutant epidermis and on its surface. A basal lamina, as determined by ultrastructure and by the immunofluorescent localization of laminin, was always found at the interface of the mutant epidermis and the invading cell population. By 19 days of development the mutant epidermis is thickened and is permeated by a network of cells including nerve fibres, Schwann cells, blood vessels, and collagen and fibronectin-secreting cells. A basal lamina always separates these groups of invading cells from the epidermal cell population.

Animals↗

Partial (localized) lipodystrophy. Report of a case with muscle and skin abnormalities.

The light and electron microscopic myopathologic and dermatopathologic features in one patient with the partial (localized) type of lipodystrophy are described. The myopathologic changes involve both the contractile elements and the intracellular organelles, especially mitochondria that show hyperplasia and structural alterations of cristae. The dermatopathologic changes consist of a reduction in subcutaneous fat, intercellular edema, and the presence of intracytoplasmic lipid droplets. This is the first report in the literature in which the myopathologic features and detailed electron microscopy of skin in this condition are described. The myopathologic features of partial lipodystrophy are compared with those of congenital generalized lipodystrophy. It is proposed that a myopathy may be one of the manifestations of partial lipodystrophy.

Adult↗

Histopathologic and morphometric evaluation of the skin abnormalities induced by erbium:YAG and carbon dioxide lasers in 10 patients.

In the 1960s, carbon dioxide (CO2) laser therapy started to be applied to eliminate wrinkles, actinic scars, and acne because of its capacity of induce intracellular water vaporization. However, recent studies have shown the efficacy of the erbium laser in removing delicate and moderate scars. Furthermore, the postoperative lesions induced by the erbium laser seem to resolve faster and with less erythematous pattern compared with lesions induced by the CO2 laser. The purpose of this study was to determine the immediate pathologic alterations caused by single applications of CO2 and erbium lasers and their association in human skin shreds. Ten white female patients aged 30 to 63 years underwent rhytidectomy, and their respective shreds, which were prepared for excision, were tattooed with the CO2 laser, the erbium laser, or a combination of both in random order and number of applications, before final removal. This project was approved by the local ethical committee. After surgical removal, these tattooed shreds were fixed in 10% buffered formalin and submitted to histopathologic analysis. Morphometric studies demonstrated the normal skin thickness and thickness of the laser-treated area, and their subtraction resulted in the ablation damage values. Residual thermal damage corresponded to the thickness of the affected skin from the most superficial layer of tissue in the laser-treated area down to the deepest dermal area with basophilic degeneration of collagen fibers. Our results showed that two CO2 applications resulted in greater ablation and residual thermal damage when compared with only one CO2 application. The same was true in comparisons of one and two applications of the erbium laser. Both results were statistically significant (p < 0.05). When one isolated erbium and one isolated CO2 application were compared, ablation damage was greater in the former group, although with no statistical significance. One CO2 plus one erbium application compared with one isolated CO2 application showed similar ablation damage but greater residual thermal damage in the latter group (p < 0.05). These observations might contribute to our understanding of the lesions caused in the human skin by erbium and CO2 lasers and eventually help determine the ideal laser combination for the appropriate surgical treatment.

Adult↗

Skin abnormalities in the National Portrait Gallery.

Pathological changes in the human body have long been recognised in painting. To assess the frequency of potential physical abnormalities reflected in paintings, we reviewed portraits on display at one visit in the National Portrait Gallery in London. We identified a number of possible abnormalities, most of them dermatological, with the commonest finding being small facial papular lesions, most likely representing either common warts or dermal naevi. This exercise however, reflects a subjective interpretation of the different artists's perceptions of their models' physical appearances.

History, 16th Century↗

Sparse hair, short stature, hypoplastic thumbs, single upper central incisor and abnormal skin pigmentation: a possible "new" form of ectodermal dysplasia.

A family is described where a mother and three sons have an unusual form of ectodermal dysplasia that may have been described in the medical literature only once before. The unusual manifestations in this family are mild short stature, sparse scalp hair, skin pigmentation and a transient urticarial-like reaction on the hands and arms. The mother and one son demonstrated a single, upper central incisor and the mother and another son had hypoplastic thumbs. The mother alone had hyperkeratosis of the palms and soles. The inheritance pattern is most likely autosomal dominant, although X-linked dominant inheritance cannot be excluded.

Adult↗

Vitamin D3 intoxication in naked mole-rats (Heterocephalus glaber) leads to hypercalcaemia and increased calcium deposition in teeth with evidence of abnormal skin calcification.

Naked mole-rats have no access to obvious sources of vitamin D and therefore have an impoverished vitamin D status. In an investigation into the effects of vitamin D supplementation, inadvertently supraphysiological doses of 130,000 times the normal dose of vitamin D were administered. Within 5 days animals appeared lethargic, with reduced food intake. All but one of the seven animals were killed and blood was collected. Plasma vitamin D metabolites 25(OH)D and 1,25(OH)2D and calcium were determined. Both vitamin D metabolite concentrations exceeded the upper limits of sensitivity of the assays (> 100 ng/ml 25(OH)D and > 210 pg/ml 1,25(OH)2D). Active calcium uptake in the intestine was evident along with concomitant increases in calcium concentration in plasma, bone, and teeth. The remaining animal survived, but showed scab-like formations in the skin around the lower jaw and along the nipple line. X-ray analyses revealed calcium deposition in these cornified regions, although there was no evidence of metastatic calcification in other tissues. Deposition of excess calcium in skin that is regularly sloughed off and in teeth that are continuously worn down and replaced may reduce the vitamin D-induced hypercalcaemia and thus alleviate the effects of vitamin D intoxication.

Animals↗

Abnormal skin wrinkling in the less affected side in hemiparkinsonism-a possible test for sympathetic dysfunction in Parkinson's disease.

Some patients with Parkinson's disease (PD) suffer from autonomic dysfunction, even in the early stage of the disease. We examined the skin wrinkling response following immersion of the hands in warm water in 18 patients with hemiparkinsonism. This test evaluates the function of the sympathetic autonomic system. Mean age of the patients was 61 +/- 10 and mean disease duration 5.5 +/- 3.5 years. Both hands of each patient were immersed in warm water for 30 minutes and the number of skin ridges of the fingertip of each finger was counted. The results of each hand were compared to those of nine healthy controls. The mean number of the ridges of the less affected hand was significantly decreased as compared to the affected hand and controls (6.1 +/- 6.8 vs 13.1 +/- 6.8 and 15.3 +/- 8.5, respectively; P < 0.01). These results suggest that autonomic dysfunction is prevalent in the less affected side of patients with PD and can be simply tested by the skin response test.

Adult↗

Cathepsin L-deficient mice exhibit abnormal skin and bone development and show increased resistance to osteoporosis following ovariectomy.

The role of cathepsin L in normal physiological processes was assessed using cathepsin L homozygous knockout mice (B6;129-Ctsl(tm1Alpk)). These mice were generated using gene targeting in embryonic stem cells. Null mice fail to express mRNA and protein to cathepsin L. They developed normally and were fertile. The distinct phenotypic change exhibited was a progressive hair loss, culminating in extensive alopecia by 9 months of age. Histological analysis of the skin from homozygous mice revealed diffuse epithelial hyperplasia, hypotrichosis, hair shaft fragmentation and utricle formation. These findings provide evidence that cathepsin L is involved in the regulation of epithelial cell proliferation and differentiation in the skin. In addition, the role of cathepsin L in bone remodelling was evaluated. Using bone histomorphometric measurements, trabecular, but not cortical, bone volume was found to be significantly decreased in the cathepsin L heterozygote and homozygote mice compared to the wild-type mice. Following ovariectomy, it was observed that loss of trabecular bone, the most metabolically active component of bone, occurred to a lesser extent in homozygote, and heterozygote mice, than was seen in wild-type mice. These observations suggest that cathepsin L is likely to have a role in controlling bone turnover during normal development and in pathological states.

Animals↗