Normal Skin Thickness Research Articles

Accelerated vascularization of a novel collagen hydrogel dermal template.

Full thickness skin loss is a debilitating problem, most commonly reconstructed using split thickness skin grafts (STSG), which do not reconstitute normal skin thickness and often result in suboptimal functional and esthetic outcomes that diminish a patient's quality of life. To address the minimal dermis present in most STSG, engineered dermal templates were developed that can induce tissue ingrowth and the formation of neodermal tissue. However, clinically available dermal templates have many shortcomings including a relatively slow rate and degree of neovascularization (∼2-4weeks), resulting in multiple dressing changes, prolonged immobilization, and susceptibility to infection. Presented herein is a novel composite hydrogel scaffold that optimizes a unique scaffold microarchitecture with native hydrogel properties and mechanical cues ideal for promoting neovascularization, tissue regeneration, and wound healing. In vitro analysis demonstrated the unique combination of improved mechanical attributes with native hydrogel properties that promotes cell invasion and remodeling within the scaffold. In a novel 2-stage rat model of full thickness skin loss that closely mimics clinical practice, the composite hydrogel induced rapid cell infiltration and neovascularization, creating a healthy neodermis after only 1week onto which a skin graft could be placed. The scaffold also elicited a gradual and favorable immune response, resulting in more efficient integration into the host. We have developed a dermal scaffold that utilizes simple but unique collagen hydrogel architectural cues that rapidly induces the formation of stable, functional neodermal tissue, which holds tremendous promise for the treatment of full thickness skin loss.

Aliskiren: Preclinical evidence for the treatment of hyperproliferative skin disorders

Psoriasis is a complex inflammatory and hyperproliferative skin disease. The pathogenesis and mechanisms involved are not completely understood, which makes treatment a difficult issue. Angiotensin II, the most active peptide of the renin-angiotensin system, seems to be involved in processes related to psoriasis pathogenesis, such as inflammation and cell proliferation. The aim of this study was to investigate the influence of renin inhibition on inflammation parameters and keratinocyte proliferation in a mouse model of chronic skin inflammation induced by croton oil. Aliskiren had anti-inflammatory effects by reducing levels of tumor necrosis factor-α and interleukin -6, and by inhibiting myeloperoxidase activity. Aliskiren also showed antiproliferative activity by reducing epidermal hyperplasia and proliferating cell nuclear antigen levels. Aliskiren treatment did not induce alterations in the cardiovascular system, normal skin thickness, and organ weight. These results suggest that aliskiren could be a valuable tool to be incorporated in the treatment of hyperproliferative and inflammatory skin disorders such as psoriasis.

Upper and Lower Eyelid Full Thickness Reconstruction Using a Retrograde Postauricular Island Flap.

Upper and lower eyelid full-thickness reconstruction in a patient without available adjacent tissue because of burns or trauma is a surgical challenge. Our patient had severe thermal burns with complete unilateral defects in both the upper and lower eyelids. Although the skin grafts survived, contraction occurred quickly, subsequent ectropion of both the upper and lower eyelids, which could have lead to exposure keratitis and blurred vision. A retrograde postauricular island flap was harvested to provide skin eyelid coverage, and the donor site was directly closed. After another 2 surgeries, normal skin thickness and a color-matched appearance were achieved, and the donor-site scar was almost invisible from the anterior view. To our knowledge, it is rare to use a retrograde postauricular island flap in a full-thickness reconstruction of both the upper and lower eyelids, but the authors have ascertained that this method may be a reliable option in such selected and challenging situations.

A clinicopathologic study of morphea in Korean patients.

The exact pathogenesis of morphea is poorly understood, and only a few clinical or histopathological studies have been conducted in Asian patients. The aim of this study was to identify the clinical and histopathological characteristics of morphea in Korean patients. We retrospectively reviewed the medical records of 101 patients whose clinicopathologic findings were compatible with morphea and analyzed demographic characteristics, number of lesions, disease subtype and histopathological findings. Overall, circumscribed morphea (52.5%) was the most common clinical type, followed by linear (28.7%), mixed (13.9%) and generalized (5.0%) type. Disease duration was positively correlated with increased thickness of the skin in 54 patients (p < 0.001). Inflammatory cell infiltration was absent in 54, mild in 30 and moderate in 14 patients. There was no significant difference in the mean ratio of lesional to normal skin thickness (L/N ratio) among four types of morphea. Disease duration was not correlated with the density of inflammatory cell infiltration (p = 0.68). There were statistically significant differences in the duration of disease according to plasma cell counts (p < 0.05). A positive correlation was found between skin thickness and disease duration, but mean L/N ratio was not significantly different among various types of morphea.

Morphology and Epidermal Thickness of Normal Skin Imaged by Optical Coherence Tomography

Background: Optical coherence tomography (OCT) is an optical imaging technology with a potential in the non-invasive diagnosis of skin cancer. To identify skin pathologies using OCT, it is of prime importance to establish baseline morphological features of normal skin. Aims: The aim of this study is to describe normal skin morphology using OCT and polarization-sensitive OCT (PS-OCT), which is a way of representing birefringent tissue such as collagen in OCT images. Anatomical locations in 20 healthy volunteers were imaged, and epidermal thickness (ET) was measured and compared to age, gender and skin colour. Methods: OCT imaging is based on infrared light reflection/backscatter from tissue. PS-OCT detects birefringence of tissue. Imaging was performed in 12 skin regions. ET was calculated from the OCT images. Results: Normal skin has a layered structure. Layering is less pronounced in adults. In glabrous skin the stratum corneum is visible. Children had larger ET (p < 0.0001). Age had a negative correlation with ET (p < 0.05). No gender- or skin-type-related differences in ET were found. Conclusion: This study contributes to understanding OCT and PS-OCT images of normal skin and indicates that OCT can be used for both the qualitative and quantitative assessment of skin.

Efficacy of spheroplastic and cell-wall competent vaccines for Mycobacterium avium subsp. paratuberculosis in experimentally-challenged baby goats

A Mycobacterium avium subspecies paratuberculosis (MAP) vaccine that reduced the incidence of clinical disease or reduced fecal shedding of MAP would aid control of Johne's disease (JD). The objective of the present study was to evaluate the efficacy of four MAP vaccine combinations, including cell-wall competent (CWC) alum adjuvant, CWC-QS21 adjuvant, cell-wall deficient (CWD) alum adjuvant and CWD-QS21 adjuvant vaccines. Eighty baby goats were vaccinated at 1 and 4 weeks of age with one of these vaccines or a sham control vaccine consisting of alum adjuvant. Kids were challenged orally with approximately 6.0 × 10 9 organisms in four divided doses of 1.5 × 10 9 organisms using a goat isolate of MAP. Vaccinated challenged and challenged control groups had 10 and 6 kids per group, respectively. Half of the kids within each group were necropsied at either 6 or 9 months post-challenge. Gross and microscopic lesions and relative number of acid-fast bacilli were evaluated and scored at necropsy. Results indicated all challenged kids had some lesions compatible with JD suggesting none of the vaccines prevented infection. Three vaccines (CWC-alum, CWC-QS21 and CWD-QS21) reduced lesion scores by 46–51% at 9 months. CWD-alum vaccine resulted in a more severe (+33.5%) lesion score than sham-vaccinated challenged control. Lesion scores were greater at 9 months than at 6 months post-challenge in the sham-vaccinated challenged group and CWD-alum vaccinated group, while lesion scores were generally stable with remaining vaccines. Mean fecal CFU/g were significantly different across time from challenge to 9-month necropsy ( p = 0.043) and the CWC-QS21 vaccine group had a marked reduction in fecal CFU/g at all time points post-challenge. A reduction in MAP CFU/g was also detected in necropsy tissues from kids given the CWC-alum, CWC-QS21 and CWD-QS21 vaccines, and increased CFU/g were detected in tissues from kids given the CWD-alum vaccine. Immunological tests evaluated included, humoral response evaluation by AGID, ELISA and Western blot, and cell mediated response by comparative PPD skin testing ( M. avium, Old Johnin, M. bovis and Lot 2 Johnin PPD's), and production of MAP induced γ-interferon. Vaccination also resulted in false-positive PPD skin test reactions for M. avium PPD, Old Johnin PPD and γ-interferon tests. When a 2-mm cutoff above normal skin thickness was used to define positive skin test reactions, false-positive reactions for M. bovis were detected in only 2 of 32 kids given a vaccine with QS21 adjuvant.

Extramammary Paget's disease treated with topical and systemic photodynamic therapy

Surgical excision and radiotherapy for extramammary Paget's disease (EMPD) at specific sites such as the groin and genitalia is often inappropriate. An 80-year-old man with histologically proven EMPD of the left groin and scrotum was referred for PDT. The lesion and normal skin thickness were measured by a 20MHz, two-dimensional 'B' ultrasound scanner (US). δ-5-Aminolaevulinic acid (ALA), was applied followed 6h later by irradiation using a filtered xenon-arc lamp. Clinical improvement was apparent four weeks after first PDT session with a reduction in ulceration and lesion size and moderate thickness reduction on US. Superficial ulceration recurred 9 months after the fifth treatment. This recurrence was treated with intravenously administered porfimer sodium. This, followed by one topical PDT treatment resulted in significant clinical and US cure and the patient remains disease free at 1-year follow-up.

Effects of tacrolimus ointment on type I (immediate and late) and IV (delayed) cutaneous allergic reactions in mice

The effects of tacrolimus ointment on immediate, late and delayed-type cutaneous allergic reactions and normal skin thickness were investigated in mice and compared with those of steroid ointments. Tacrolimus ointment had no effect on ear edema in the immediate phase of the biphasic reaction and did not inhibit passive cutaneous anaphylaxis, but in the late phase of the biphasic reaction, it inhibited the ear edema. It also showed a clear inhibitory effect on the delayed-type reaction. These evidence suggest that the clinical effect of tacrolimus ointment against atopic dermatitis (AD) may be mainly due to its inhibitory action on late and delayed-type reactions. The steroid ointments inhibited all the reactions mentioned above, and the effects were more potent than those of tacrolimus. Moreover, they also decreased the normal ear thickness, suggesting that the inhibitory effect of the steroid ointments was partially due to skin atrophic action. The same ointments applied to the ears during the induction phase showed an enhancement of delayed-type reaction at the effector phase. Tacrolimus ointment did not show such a rebound effect or skin atrophy. Thus, tacrolimus ointment was expected to be more useful than the steroids for the treatment of AD.

Ultrasound of normal skin.

The authors have used a commercially available real-time sector scanner and a 10-MHz probe with a built-in water path for B-mode imaging of the normal skin. Measurements have been performed in 10 volunteers at 18 sites on the body surface. Normal skin thickness ranges from 1.4 mm at the dorsal aspect of hand to 4.8 mm at the heel. Clinical applications of B-mode imaging of the skin are discussed.

Late Nonstochastic Changes in Pig Skin after β Irradiation

Late radiation-induced changes in pig skin have been assessed following irradiation with beta-rays from a 22.5- or 15-mm-diameter 90Sr/90Y source and a 19- or 9-mm-diameter 170Tm source. Late damage, in terms of dermal atrophy, was assessed 2 years after irradiation from measurements of dermal thickness in irradiated and normal skin. After 90Sr irradiation maximum atrophy, a dermal thickness of 40-50% of the control value, occurred at a dose of approximately 40 Gy from the 22.5-mm source and approximately 75 Gy from the 15-mm source. In the case of 170Tm the 19- and 9-mm sources produced similar degrees of atrophy at equal doses. Maximum atrophy occurred at approximately 70 Gy, when the dermis was approximately 70% of the thickness of normal skin. Significant late tissue atrophy was seen at doses, from both types of radiation, which only produced minimal erythema in the early reaction. Such late reactions need to be taken into account when revised radiological protection criteria are proposed for skin.

Microsomal enzyme induction and gingival enlargement in subjects taking phenytoin

Subjects taking the anticonvulsant phenytoin were examined for gingival enlargement and skin-fold thickness. Induced synthesis of their hepatic microsomal enzymes was estimated by measuring urinary D-glucaric acid. Gingival enlargement was positively correlated ( p < 0.05) with urinary D-glucaric acid. Although skin-fold thickness was not correlated with either urinary D-glucaric acid or gingival enlargement, mean gingival enlargement was greater in some subjects who did have an increased skin thickness than in those with normal skin thickness. The results suggest that induction of microsomal enzyme synthesis, as estimated by urinary D-glucaric acid, is related to taking phenytoin, as is gingival enlargement, and that there are other factors that affect both phenomena.

The effect of occlusive and semipermeable dressings on the mitotic activity of normal and wounded human epidermis.

Summary.— Occulusion has been shown to increase the rate of closure of superficial woulds. However, it has laos been shown to inhibit cell division both of psoriatic lesions and stripped skin. This work was undertaken to investigate further this appartent anomaly. Forur dressings—an occulsice, adhesive tape; the adhesive backing from thsi tape; a less occlusive adhesive tape; and an occulsive, non-adhesive film, were used to cover regions of normal and stripped skin for periods from 2 to 6 days. The results show a slight increase in mitotic rate and epidermal thickness of normal skin, under all dressings. These results are discussed and it is suggested that the less occlusive films might be of benefit in accelkerating the healing of wounds without adding the risk of infection seen under complete occulusion.

Skin collagen and thickness in simple obesity.

The effects of stretching of the skin on its collagen content and thickness have been studied in a group of subjects with chronic obesity. Despite the increase in skin surface a normal skin thickness, collagen content, and density were maintained. It is concluded that the skin stretching induced by prolonged obesity led to hypertrophy of collagen and that this had maintained both skin thickness and collagen content. It is not known whether this is due to enhanced synthesis or decreased degradation.