Skin diseases are associated with environmental factors and a public health approach is particularly important. We determined the prevalence of skin conditions and associated socioeconomic factors in primary school children in Turkey. A questionnaire for determining the socioeconomic level and a complete dermatologic examination were performed in 785 children in two primary schools in different socioeconomic areas of suburban and central Manisa, Turkey. The study included 345 (43.9%) girls and 440 (56.1%) boys with a mean age of 9.25 +/- 1.55 (range 6-14 years). Infectious skin diseases were frequently observed: pediculosis capitis in 74 children (9.4%), scabies in 17 (2.2%), viral skin diseases in 30 (3.8%), and fungal infections in 6 (0.7%). The other common conditions were melanocytic nevi (14.4%), keratosis pilaris (12.5%), pityriasis alba (12%), xerosis (11.8%), and atopic dermatitis (6.8%). Pediculosis capitis, acne, and dandruff were more common in girls. The rate of infections, atopic dermatitis, xerosis, and pityriasis alba were significantly higher in the school children with poor socioeconomic conditions. Improvement in socioeconomic conditions along with education may be needed to decrease the prevalence of some of these skin disorders in order to decrease costs related to treatment.

Although there have been numerous reports describing the isolation of liver progenitor cells from adult liver, their exact origin has not been clearly defined; and the role played by mature hepatocytes as direct contributors to the hepatic progenitor cell pool has remained largely unknown. Here we report strong evidence that mature hepatocytes in culture have the capacity to dedifferentiate into a population of adult liver progenitors without genetic or epigenetic manipulations. By using highly-purified mature hepatocytes, which were obtained from untreated, healthy rat liver and labeled with fluorescent dye PKH2, we found that hepatocytes in culture gave rise to a population of PKH2-positive liver progenitor cells. These cells, Liver Derived Progenitor Cells or LDPCS, which share phenotypic similarities with oval cells, were previously reported to be capable of forming mature hepatocytes both in culture and in animals. Studies done at various time points during the course of dedifferentiation cultures revealed that hepatocytes rapidly transformed into liver progenitors within one week through a transient oval cell-like stage. This finding was supported by lineage-tracing studies involving double-transgenic AlbuminCreXRosa26 mice expressing β-galactosidase exclusively in hepatocytes. Cultures set up with hepatocytes obtained from these mice resulted in generation of β-galactosidase-positive liver progenitor cells demonstrating that they were a direct dedifferentiation product of mature hepatocytes. Additionally, these progenitors differentiated into hepatocytes in vivo when transplanted into rats that had undergone retrorsine pretreatment and partial hepatectomy. Conclusion Our studies provide strong evidence for the unexpected plasticity of mature hepatocytes to dedifferentiate into progenitor cells in culture; and this may potentially have a significant impact on the treatment of liver diseases requiring liver or hepatocyte transplantation.

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Widespread use of liver transplantation in the treatment of hepatic diseases is restricted by the limited availability of donated organs. One potential solution to this problem would be isolation and propagation of liver progenitor cells or stem cells. Here, we report on the isolation of a novel progenitor cell population from unmanipulated (that is, no prior exposure to chemicals and no injury) adult rat liver. Rat liver cells were cultured following a protocol developed in our laboratory to generate a unique progenitor cell population called liver-derived progenitor cells (LDPCs). LDPCs were analyzed by fluorescence-activated cell sorting, real-time polymerase chain reaction (RT-PCR), immunostaining and microarray gene expression. LDPCs were also differentiated into hepatocytes and biliary epithelium in vitro and examined for mature hepatic markers and urea and albumin production. These analyses showed that, LDPCs expressed stem cell markers such as cluster domain (CD)45, CD34, c-kit, and Thy 1, similar to hematopoietic stem cells, as well as endodermal/hepatic markers such as hepatocyte nuclear factor (HNF)3␤, hematopoietically-expressed homeobox gene-1, c-met, and transthyretin. LDPCs were negative for OV-6, cytokeratins (CKs), albumin, and HNF1␣. The microarray gene expression profile demonstrated that they showed some similarities to known liver progenitor/stem cells such as oval cells. In addition, LDPCs differentiated into functional hepatocytes in vitro as shown by albumin expression and urea production. In conclusion, LDPCs are a population of unique liver progenitors that can be generated from unmanipulated adult liver, which makes them potentially useful for clinical applications, especially for cell transplantation in the treatment of liver diseases. Liver Transpl 14: [333][334][335][336][337][338][339][340][341][342][343][344][345] 2008 Diseases of the liver are common causes of morbidity and mortality in the world. 1 Despite the high incidence of liver diseases that result in liver dysfunction and failure, current medical therapies are limited to supportive care, rather than curative approaches, with the possible exception of liver transplantation.Liver transplantation is considered to be the standard treatment for end-stage liver disease. 2 Unfortunately, its extensive application is restricted by the limited availability of donor organs. In addition, liver transplantation is associated with significant morbidity and mortality. As most liver disorders result from hepatocyte dysfunction, there has been great interest in transplantation of isolated hepatocytes. However, their clinical application is also dependent on the availability of good quality donor livers.To overcome the problem of limited donor organs and to make hepatocytes available for other applications, several approaches to isolate and propagate liver stem cells or progenitor cells have been developed. 3,4 It is