The Keio Journal of Medicine


Stem cell research at The German Primate Centre Goettingen - Projects and perspectives
Thomas Mueller

In June 2005 a new stem cell research group was founded at the German Primate Research Centre (DPZ) in Goettingen, Germany. It is a non-profit organization with service and research function. The DPZ, as a member of the Gottfried Wilhelm Leibniz Science Community, is unique in Europe, internationally acknowledged, providing field stations in Peru, Madagascar and Indonesia. Furthermore, the DPZ is closely connected to the Georg-August-University and clinics in Goettingen, the Max-Planck Society and primate centres in Europe and all over the world. Our researchers utilize non-human primates as model-organisms for human diseases and physiology and to study highly evolved behaviour. The institute is structured in infectious disease research, organismic primate biology and neurosciences comprising 10 subdepartments. The breeding facility of the DPZ sustains roughly 1200 monkeys, comprising rhesus monkey, marmoset monkey, cynomolgus monkey, hamadryas baboon, lion-tailed macaque, tree shrew, squirrel monkey, and cotton-top tamarin. The primary aim of stem cell research group is the establishment of new embryonic stem cell lines from the marmoset monkey. These cell lines will be used as model systems to study germ layer development in early primate embryos. In respect thereof our special interest is on epithelial-mesenchymal-transition (EMT) which is the precondition for gastrulation on the cellular level. Defective gastrulation may cause caudal dysplasia and associated mesodermal anomalies. Furthermore, investigation of EMT in ESC might significantly enhance our general understanding of pluripotency.

Genetic testing in colorectal cancer: Who, when, how and why
Nicholas O. Davidson

Colorectal cancer (CRC) is among the most prevalent and preventable forms of cancer worldwide, accounting for over 600,000 deaths in 2005. Both genetic and environmental factors contribute to cancer etiology and estimates suggest that at least one third of CRC has a familial component. There is increased awareness of a strong genetic component to CRC risk, with the identification of several high penetrance alleles that predict increased CRC susceptibility. These include familial adenomatous polyposis (FAP), linked to mutations or deletions of the APC tumor suppressor gene, as well as Lynch syndrome (formerly known as hereditary non-polyposis colorectal cancer or HNPCC), which is linked to mutations or deletions of one or more mismatch repair genes including MLH1, MSH2 and MSH6. In addition, mutations in genes encoding key signaling molecules have been linked to autosomal dominant hamartomatous syndromes that are associated with increased susceptibility to CRC. These include Peutz-Jeghers syndrome, which is linked to mutations in STK11/LKB and Juvenile polyposis, which is linked to mutations in the genes encoding SMAD4 and BMPR1A. In addition to these high penetrance autosomal dominant alleles, recessive mutations in the MYH mismatch repair gene are associated with a phenotype similar to FAP. With the widespread availability of genetic testing for these alleles, physicians will be faced with a complex array of choices in terms of advocating who should be tested, when should such testing take place, how it should be conducted and interpreted and why it changes the management and outcomes for the patient and his or her family.

Basic aspect and clinical impact of anticancer drug paclitaxel
Woo Man Han

Paclitaxel is an anticancer drug that has mostly come under the spotlight in more than 60 countries in the world as the primary or secondary therapeutic agent in the treatment of ovarian, breast, lung and gastric cancers. The mechanism of anticancer action of this drug is identified as an inhibition of cancer cell mitosis by stabilizing tubulin/microtubule system. In 1967, paclitaxel is extracted from the bark of the Pacific Yew tree (Taxus brevifolia) and identified as an active anticancer substance by the Research Triangle Institute (RTI) of the US Department of Agriculture and the National Cancer Institute (NCI) under the National Institutes of Health (NIH) for the joint research of developing plant-oriented anticancer drugs. Pacific Yew contains only 0.02% of paclitaxel and distributed in a limited area, the Pacific Coast, thus many scientists have tried to synthesize a large quantity of paclitaxel at low cost. However, the chemical structure of paclitaxel (5,20-epoxy-1,2,4,7,10,13- hexahydroxytax-11-en-9-one-4,10-diacetate-2-benzoate-13-ester-(2R,3S)-N-benzoyl-3-phenylisoserine) is required 36 chemical steps to be made. Therefore, the production of this agent by economical artificial synthesis is impossible. In the middle of 1980s, more efficient semi-synthesis of paclitaxel from a taxan ring-containing substance baccatin III has been reported. Currently, a multinational pharmaceutical company produces a large quantity of paclitaxel using this technology. At the Keio Medical Society meeting, we will overview the history regarding this anticancer agent, i.e., identification of anticancer mechanisms, investigation of synthesis technology, identification of clinical implications. In addition, details of our technology of paclitaxel semi-synthesis will be discussed extensively.

Mouse embryo/sperm bank system
at the Center for Animal Resources & Development (CARD), Kumamoto University
Naomi Nakagata

In 1998, the Center for Animal Resources and Development (CARD) at Kumamoto University in Japan expanded their embryo/sperm bank on a large scale. In particular the bank is intended to safeguard unique genetic material and to make it readily available to the scientific community. The bank contains mutant and transgenic stocks, congenic lines and wild mice. Our bank system offers the following essential services. 1. Freezing of embryos and spermatozoa: In general 2-cell embryos obtained by fertilization in vitro are cryopreserved by a simple vitrification. For most strains our goal is to freeze a minimum of 300 embryos. We also freeze epididymal spermatozoa from mutant and transgenic lines. 2. Viability testing of frozen stocks: The viability of all stocks is tested by transferring samples of thawed embryos to foster mothers to assess the proportion capable of normal development to live-born young. The foster mothers and offspring are maintained in an isolator until regular microbiological diagnostic investigations. In the case of frozen spermatozoa, a part of each stock is thawed and the motility and fertilization ability of them are observed. 3. Analysis of DNA: In the transgenic lines, the transgenicity is confirmed by PCR analysis of genomic DNA from the tail tissue of 4-week-old mice. 4. Regular microbiological diagnostic investigations: Some of the offspring from frozen embryos are tested for viral, bacterial and parastic pathogens at 8 weeks of age. We currently have 1,000 cryopreserved strains and more than 500,000 frozen embryos. We also have 15,000 straws containing frozen spermatozoa from transgenic mice.