New Approaches in the Differentiation of Human Embryonic Stem Cells and Induced Pluripotent Stem Cells toward Hepatocytes

Orthotropic liver transplantation is the only established treatment for end-stage liver diseases. Utilization of hepatocyte transplantation and bio-artificial liver devices as alternative therapeutic approaches requires an unlimited source of hepatocytes. Stem cells, especially embryonic stem cells, possessing the ability to produce functional hepatocytes for clinical applications and drug development, may provide the answer to this problem. New discoveries in the mechanisms of liver development and the emergence of induced pluripotent stem cells in 2006 have provided novel insights into hepatocyte differentiation and the use of stem cells for therapeutic applications. This review is aimed towards providing scientists and physicians with the latest advancements in this rapidly progressing field

Present state and future perspectives of using pluripotent stem cells in toxicology research

The use of novel drugs and chemicals requires reliable data on their potential toxic effects on humans. Current test systems are mainly based on animals or in vitro–cultured animal-derived cells and do not or not sufficiently mirror the situation in humans. Therefore, in vitro models based on human pluripotent stem cells (hPSCs) have become an attractive alternative. The article summarizes the characteristics of pluripotent stem cells, including embryonic carcinoma and embryonic germ cells, and discusses the potential of pluripotent stem cells for safety pharmacology and toxicology. Special attention is directed to the potential application of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) for the assessment of developmental toxicology as well as cardio- and hepatotoxicology. With respect to embryotoxicology, recent achievements of the embryonic stem cell test (EST) are described and current limitations as well as prospects of embryotoxicity studies using pluripotent stem cells are discussed. Furthermore, recent efforts to establish hPSC-based cell models for testing cardio- and hepatotoxicity are presented. In this context, methods for differentiation and selection of cardiac and hepatic cells from hPSCs are summarized, requirements and implications with respect to the use of these cells in safety pharmacology and toxicology are presented, and future challenges and perspectives of using hPSCs are discussed

Persistent Spontaneous Pneumothorax for Four Years: A Case Report

Pneumothorax, defined as the presence of air in the pleural space, is usually classified as spontaneous or traumatic; it is unusual for pneumothorax to be categorized as being acute or chronic. Even if conservative treatment is chosen, the pneumothorax is cured when air in the pleural space dissolves into the venous blood. A 50-years-old Japanese man with no prior medical history was referred to our department with a right pneumothorax and two rightsided pulmonary nodules on chest X-ray and CT. The chest radiographs of past mass screening which was taken four years ago showed right pneumothorax and right-sided pulmonary nodules. From then, all chest radiograph and chest computed tomography showed right pneumothorax and pulmonary nodules. But he underwent no medical interventions. We designed to perform an operation for a treatment of right pneumothorax and the diagnosis of pulmonary tumors. We underwent right upper lobectomy and pleural decortication under video assisted thoracic surgery. We obtained pathological diagnosis of inflammatory pseudotumor and surrounding atelectasis. He was cured from pneumothorax and pulmonary tumors. A unique case of spontaneous pneumothorax presenting with a pleural air space that was confirmed by chest radiographs and computed tomography examinations over a 4-year period is reported

Search for sequential heavy leptons in e+e- collisions at √s¯=52 GeV

We have searched for new sequential heavy leptons L± in e+e- collisions at √s =52 GeV using the TOPAZ detector at the KEK storage ring TRISTAN. In the collected data with an integrated luminosity of 3.6 pb-1, no evidence for L± production has been observed. A lower mass limit for L± is determined to be 25.5 GeV/c2 at 95% confidence level

Search for Top Quark in e+e- Collisions at sqrt[s]=52 GeV

We searched for possible signatures of top-quark production in 508 e+e- hadronic annihilation events collected at sqrt[s]=52 GeV by the TOPAZ detector at the KEK e+e- collider TRISTAN. The observed hadronic cross section and shape of hadronic events are consistent with the standard-model predictions without top quarks. A lower limit (95% confidence level) on the mass of the lightest top meson is set at 25.8 GeV