Gentaro Uchida

The mechanism of epidermal hyperpigmentation in café-au-lait macules of neurofibromatosis type 1 (von Recklinghausen's disease) may be associated with dermal fibroblast-derived stem cell factor and hepatocyte growth factor

Summary Background The mechanism of the accentuated melanization in café‐au‐lait macules (CALMs) in patients with neurofibromatosis type 1 (NF1; von Recklinghausens disease) has not been elucidated.

Effects of all-trans retinoic acid on melanogenesis in pigmented skin equivalents and monolayer culture of melanocytes

The effects of all-trans retinoic acid (RA) on melanogenesis and the mechanism of its action in topical treatment have not been elucidated. The purpose of this study was to determine the effects of RA on melanogenesis in the pigmented skin equivalent as well as in monolayer culture of melanocytes, and to determine whether RA, hydroquinone (HQ), and hydrocortisone (HC) show synergistic depigmenting effects in combined treatments of each other. The suppressing effect of RA on melanogenesis was not observed in pigmented skin equivalents and monolayer culture of murine and human melanocytes, although HQ showed strong inhibition of melanogenesis. The synergistic effects between RA, HQ, and HC were not particularly seen. The results suggested that RA neither has direct inhibitory effects on melanogenesis of melanocytes, nor influences the cell-cell interactions between melanocytes, keratinocytes and fibroblasts, such as paracrine actions with regard to melanin production. The role of RA in bleaching treatments appears to be in other specific actions, such as promotion of keratinocytes proliferation and acceleration of epidermal turnover.

Lower extremity lymphedema index: a simple method for severity evaluation of lower extremity lymphedema.

Measurement of the circumference is the most commonly used method for evaluating extremity lymphedema. However, comparison between different patients is difficult with this measurement. To resolve this problem, we have formulated a new index, lower extremity lymphedema (LEL) index, which can be easily obtained from measurements of the body. We evaluated correlation between lower LEL index and clinical stage in patients with LEL. The LEL indices were significantly correlated with clinical stages and could be used as a severity scale. The LEL index makes objective assessment of the severity of lymphedema through a numerical rating, regardless of the body type. This numerical rating makes the index useful for evaluation of lymphedema severities between different cases.

Tretinoin reverses upregulation of matrix metalloproteinase-13 in human keloid-derived fibroblasts

Abstract Keloids are skin abnormalities that are characterized by excessive deposition of collagen bundles in the dermis. Patients with keloids complain not only about their cosmetic appearance, but also about continuous itching and/or tenderness associated with chronic inflammation. Degradation of extracellular matrix (ECM) may be upregulated, associated with the expansion of keloids into circumferential skin, and high metabolic activity of keloid tissues may be due to increased matrix metalloproteinase (MMP) activity. Based on these hypotheses, we examined differences in expression of MMP‐1, MMP‐8, and MMP‐13 between keloid‐derived and normal dermal fibroblasts. Since retinoids are potent inhibitors of MMPs in the treatment of photoaged skin and cancers, we also examined whether or not tretinoin affects MMP expression of keloid‐derived fibroblasts. The results of real‐time polymerase chain reaction and ELISA demonstrated significant upregulation of MMP‐13 and significant downregulation of MMP‐1 and MMP‐8 in keloid‐derived fibroblasts, at both mRNA and protein levels. MMP‐1 mRNA expression in the control group was significantly upregulated after the addition of tretinoin, whereas no significant change was observed in the keloid group. MMP‐8 mRNA expression in the control group was significantly upregulated by tretinoin, with the peak at 12 h, while no significant change was observed in the keloid‐derived fibroblasts. In contrast, the remarkably elevated MMP‐13 mRNA expression in the keloid group was significantly suppressed, with the peak suppression at 12 h after addition of tretinoin, while MMP‐13 mRNA expression in the control group was not significantly changed. The decrease in MMP‐1 and MMP‐8 may contribute to accumulation of type I and type III collagen in keloid tissues, and this mechanism may be modulated by molecular interaction with MMP‐13. Tretinoin appeared to reverse the abnormal expression profile of MMPs in keloid‐derived fibroblasts, such as markedly elevated expression of MMP‐13, partly through inactivation of AP‐1 pathway. The present results suggest that tretinoin may be clinically useful to improve the chronic inflammation seen in keloids and prevent expansion of keloid tissues into circumferential normal skin.

Correlation between age and the secretions of melanocyte-stimulating cytokines in cultured keratinocytes and fibroblasts

Background  The majority of skin changes associated with ageing are caused by photoageing and reflect cumulative sun exposure. Although the actinic damage plays a major role in skin pigmentation, it is also important to examine the effects of chronological cellular ageing on the pigmentation. The chief cellular components of the skin other than melanocytes are keratinocytes and fibroblasts, and the influences of age‐related changes in those cells on skin pigmentation have not been elucidated.

Intravascular stenting (IVaS) for safe and precise supermicrosurgery.

The diameter of very small vessels (about 0.5 mm or less) causes difficulties in placing forceps into the lumen and in completing anastomosis without inadvertently catching the back wall during supermicrosurgery. The insertion of nylon monofilaments into small vessels has overcome this problem. We implanted superficial inferior epigastric arterial (SIEA) flaps in 10 rats and also performed supermicroanastomosis (diameter, 0.15 mm) using SIEA flaps in mice. The back wall was never inadvertently caught using the intravascular stenting (IVaS) method, and the immediate patency rate was 100%. An advantage of using nylon for IVaS is that various sizes can be selected. We successfully anastomosed vessels with a minimum diameter of 0.15 mm. Even smaller vessels can be precisely and safely anastomosed using the IVaS method.

Elevated expression of hepatocyte and keratinocyte growth factor in cultured buccal-mucosa-derived fibroblasts compared with normal-skin-derived fibroblasts

Oral mucosa heals faster with less scar formation than skin and a hypertrophic scar is very rare in the oral cavity, but its mechanism has not been elucidated enough. To elucidate whether or not there are differences in growth factor expression between fibroblasts derived from buccal mucosal and normal skin, we investigated the expression of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF) and stem cell factor (SCF) by cultured fibroblasts. The semiquantitative RT-PCR revealed that the expression of HGF and KGF transcripts by buccal mucosal fibroblasts was significantly elevated compared with that by dermal fibroblasts. In parallel, ELISA revealed the significant increase of HGF production by buccal mucosal fibroblasts. The level of production of SCF protein did not differ significantly. Our study suggests that increased expression of HGF and KGF by buccal mucosal fibroblasts may partly be responsible for the faster wound healing with less scar formation in the oral cavity compared with normal skin.

Pretreatment with topical all-trans-retinoic acid is beneficial for wound healing in genetically diabetic mice

Abstract Objective: Topical pretreatment with all- trans -retinoic acid (atRA) is known to improve healing of cutaneous wounds. We tested the effect of atRA on wound healing of genetically diabetic db/db mice. It is known that cutaneous wounds of db/db mice show delayed wound healing due to impaired wound contraction, delayed granulation tissue formation and underexpression of keratinocyte growth factor (KGF). Methods: 0.1% atRA in 100 mg aqueous gel was applied to the back skin of db/db mice as well as to their normal heterozygous littermates, db/+ mice, for five consecutive days, and 2 days after completion of the atRA treatment, two round excisional wounds were created down the panniculus carnosus with a 6-mm punch biopsy on the back skin of each mouse. Results: After 5 days treatment with 0.1% atRA, significant hypertrophy of the epidermis and dermis, neovascularization, and inflammatory cell invasion were seen in the skin of the db/db mice, but these effects were seen only weakly in db/+ mice. Wounds in atRA-treated db/db mice closed more rapidly than those in vehicle-treated db/db mice. KGF mRNA expression, which is usually significantly lower in db/db mice than in normal mice, in wounds of atRA-treated db/db mice on day 1 of treatment was as strong as in db/+ mice. Conclusion: Pretreatment with atRA reversed the impaired wound healing in db/db mice.

Differential expression of heparin-binding EGF-like growth factor (HB-EGF) mRNA in normal human keratinocytes induced by a variety of natural and synthetic retinoids

Abstract It was recently revealed that epidermal growth following topical treatment with all‐trans retinoic acid (atRA) was at least partly induced by heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF) released from suprabasal keratinocytes. Since proliferation of keratinocytes appears to be one of the critical roles of atRA in depigmentation treatment and promotion of wound healing, HB‐EGF is considered suitable for assessing the therapeutic value of topical retinoids. In this study, HB‐EGF mRNA expression in normal human keratinocytes after atRA treatment was examined, and the effects of a variety of natural and synthetic retinoids were compared. The results of reverse transcription polymerase chain reaction (RT‐PCR) suggested that induction of differentiation increased HB‐EGF mRNA expression in cultured keratinocytes. Real‐time PCR analyses revealed that HB‐EGF mRNA expression was elevated dose‐dependently with atRA, peaking at 12 h. This elevation was more prominent in confluent keratinocytes than in subconfluent cells, suggesting that differentiated keratinocytes are more subject to stimulation of HB‐EGF expression by atRA than proliferating keratinocytes. HB‐EGF mRNA was upregulated in differentiation‐induced keratinocytes by all retinoids used in this study at 1 µmol/l, and marked upregulation was seen when treated with three isotypes of retinoic acid (atRA, and 9‐cis and 13‐cis retinoic acid). RARα‐selective agonists (Am80, Am580, ER‐38925, and TAC‐101) and a panagonist of RARs (Re80) caused relatively low elevation of HB‐EGF transcripts, as did all‐trans retinol (Rol) and all‐trans retinal (Ral). Although another panagonist (Ch55) showed the highest elevation of HB‐EGF mRNA, it was relatively cytotoxic at the concentration employed. Ral and Rol were found to upregulate HB‐EGF when used at 100 µmol/l to 1 mmol/l, to a similar extent of atRA at 1–10 µmol/l. The capacity of retinoids to upregulate HB‐EGF may be an important index for investigation and development of an ideal synthetic retinoid, which has maximum benefits and minimum side‐effects

Topical negative pressure using a drainage pouch without foam dressing for the treatment of undermined pressure ulcers.

Abstract:Topical negative pressure is gaining popularity as an acute and chronic wound management technique. In general, foam dressing is applied to the wound surface to maintain negative pressure. Due to the potential for clogging by the foam dressing, topical negative pressure cannot be used when there is a high volume of necrotic tissue or massive infection present. In this study, topical negative pressure was applied using a drainage pouch without any dressing. Topical negative pressure was applied to 8 patients with 9 pressure ulcers complicated by undermining. This approach was effective in the treatment of all 9 ulcers and allowed the wounds to be visualized while maintaining negative pressure. Since this technique can be performed without foam dressing, it can be used to treat early-stage infectious pressure ulcers in which there is a lot of necrotic tissue. Conclusion:Topical negative pressure without dressing is an extremely effective treatment of pressure ulcers complicated by undermining.