Pancreatic Exocrine and Endocrine Cell Differentiation during Pancreatic Regeneration / 한양의대학술지

Pancreatic tissue is maintained by a simple proliferation of the preexisting cells in adulthood, whereas, they are dynamically derived from precursor/ stem cells from ductal epithelia during prenatal life. It has been known that tissue regeneration rarely occurs in the normal adult pancreas, particularly in the human pancreas. However, regeneration can be experimentally induced in the adult pancreas in response to various tissue injuries such as partial resection, pancreatitis by obstruction of the duct, and chemical insults. Regenerating pancreatic tissue shares a common morphogenic feature of "neogenic regeneration" in all regenerating animal models. Neogenic regeneration occurs at the site of tissue injury by forming small tubular structures with elongated epithelial cells (ductules) which grow to form pancreatic ducts and acini. The endocrine cells, including insulin secreting beta cells, are also derived from these ductules. As a sequential process of neogenesis, the regenerating tissue becomes heterogeneous in composition. Some areas were composed by tubules and ductules in surrounding loose connective tissue while others were denser with differentiating acini derived from tubules or ductules. Such neogenic regeneration mimics tissue development during fetal pancreatic organogenesis. In the process of pancreatic neogenesis, we found unique expressions of bioactive proteins such as nestin and clusterin as morphogenic factors. It is likely that the stem/precursor cells could be recapitulated and regenerated to functional cells, including endocrine and exocrine pancreatic cells with acinar and ductal cells during neogenic regeneration of the pancreas.

Superficial Cutaneous Mycoses in Korea / 한양의대학술지

Superficial cutaneous mycosis is mycotic infection of the epidermis of the skin, and one of common dermatoses in Korea. They have close relationship between host (human) and fungi. Their clinical patterns and incidence, and their causative fungi may change with social environments and life patterns. Since 1945, GNP has been increased explosively, more than 243 folds, and economic developments brought abrupt changes of social environments and life patterns in Korea. Furthermore, there had been great social events during this period; Korean War in 1950-1953, the Asian Game in 1986, the Olympic Game in 1988 and the World Cup in 2002. Those events gave much chances for dermatophytes to move and change. Tinea pedis is the most common dermatophytosis and has been increased from 26% of all dermatophytosis in late 1950s to 40.9-42.2%. And tinea unguium(onychomycosis) has been increased as tinea pedis does; Its proportion was 2.8% in late 1950s, and 17% in 1990s. The patients with tinea pedis have high family infection rate and also have high coexisting dermatophytosis. The most common isolate was Trichophyton(T.) rubrum, followed by T. mentagrophytes and Epidermophyton floccosum. Tinea capitis showed the most dramatic changes; its incidence was the highest just after Korean war and decreased abruptly since 1970s. Microsporum(M.) ferrugineum was the most common isolates till 1970s, and abruptly decreased and now nearly disappeared. Trichophyton(T.) violaceum was isolated in Cheju island. After Korean war, T. schoenleinii was isolated from favus and is disappeared. M. canis was isolated for the first time in 1959 and has been the most common isolates since late 1970s. T. verrucosum was isolated in 1986, and T. tonsurans was isolated for the first time in 1995 and spread among wrestlers, Judo players and Korean wrestlers. It might be imported by wrestlers with sport exchanging program. In cidence of tinea cruris was dramatically changed and was 5% of all dermatophytosis in 1940s, and 26.6-39.1% in 1990s. Those changes might be related to change of life patterns. Proportion of cutaneous candidiasis among superficial cutaneous mycosis was 1.9% in 1960s, 6.7% in 1973, 14.6% in 1976-1985, and 7.4% in 1989-1992. Proportion of pityriasis versicolor among superficial cutaneous mycosis was 12.1% in 1973, 7.7% in 1976-1985, and 7.7% in 1989-1992. Research for Malassezia have been increasing since late 1990s and that will bring us many new informations.

Malassezia(Pityrosporum) Infections of the Skin / 대한의진균학회지

The lipophilic yeast Pityrosporum ovale (Malassezia sp.) is a member of the normal human cutaneous flora in adults but also associated with several skin diseases. Treatment of P. ovale related diseases include topical and systemic antifungal therapy In pityriasis versicolor, under the influence of predisposing factors, P. ovale changes from the round blastospore form to the mycelial form. Pityriasis versicolor may be treated with topical treatment. However, with more extensive lesions, in patients with recurrence of the disease or patients not responding to topical therapy short term treatment with oral antifungal drugs is very effective. Recurrence is a great problem in pityriasis versicolor with a recurrence rate of 60% within 1 year. To avoid this oral ketoconazole 400mg once monthly or 200mg on 3 consecutive days every months have a documented effect. Pityrosporum folliculitis is a chronic disease characterized by pruritic follicular papules and pustules located primarily on the upper trunk, neck and upper arms. In direct microscopy clusters of round budding yeast cells are found. The same treatments used for pityriasis versicolor are effective in the treatment of Pityrosporum folliculitis. However, the treatment period has to be prolonged. With topical therapy 3 to 4 weeks of daily treatment and then prophylactic therapy once or twice weekly is often necessary to first clear the disease and then to avoid recurrence. However, due to the presence of P. ovale deep down in the follicle several patients will not be completely cleared with topical therapy and systemic therapy may be necessary. There are now many studies indicating that J9 ovale plays an important role in seborrheic dermatitis. Many of these are treatment studies showing a good effect of antimycotics parallelled by a reduction in number of organisms. Severe seborrheic dermatitis often difficult to treat is associated with AIDS. In peripheral blood from a high number of patients with seborrheic dermatitis we found an increase in number of natural killer T-cells and decreased PHA and Con-A stimulation. Secondary we found low serum IgG antibody titres in patients compared to controls. Other studies have found a reduced lymphocyte stimulation reaction when lymphocytes from patients with seborrheic dermatitis were stimulated with a P. ovale extract. Additionally, IL-2 and IFN gamma pruduction by lymphocytes from patients was markedly depressed and IL-10 sythesis were increased after stimulation with p. ovale extract. Several studies have clearly documented that antifungal therapy is very effective in the treatment of seborrheic dermatitis.