Performance Evaluation of the ARCHITECT i2000 for the Determination of Whole Blood Cyclosporin A and Tacrolimus / 임상검사와정도관리

Maintaining immunosuppressant concentrations within the therapeutic range in organ recipients requires regular monitoring. The blood concentrations of immunosuppressants are routinely measured using one of several automated immunoassays, such as chemiluminescence immunoassays (CLIAs) and liquid chromatography-tandem mass spectrometry (LC-TMS). The ARCHITECT i2000 immunoassay analyzer (Abbott Diagnostics, USA) was developed as an automated CLIA analyzer for the measurement of cyclosporin A and tacrolimus in whole blood. Here, the precision and linearity of the ARCHITECT i2000 analyzer for the detection of cyclosporin A and tacrolimus in whole blood were evaluated according to Clinical and Laboratory Standards Institute guidelines and were compared with those of an LC-TMS detection method. The total coefficient of variation for the two drugs was less than 10%, and they showed linearity values of 0.97 or more, which was within the manufacturer's range. The measurements of both immunosuppressants by the ARCHITECT i2000 were closely correlated with measurements determined by LC-TMS. However, most measurements were lower with LC-TMS than with the ARCHITECT i2000. Measurement of cyclosporin A and tacrolimus in whole blood using the ARCHITECT i2000 showed very satisfactory performance in terms of precision and linearity as well as good correlation with the comparative method.

Rapidly Progressive Small Bowel Necrosis in a Previously Healthy Child without Proven Mechanical Obstruction / 대한소아소화기영양학회지

Bowel ischemia is a life-threatening surgical emergency. We report a case of rapidly progressive bowel necrosis in a previously healthy child without proven mechanical small bowel obstruction. The definite diagnosis was established at the time of an exploratory operation. Of note, imaging studies and even a laparotomy did not reveal any evidence of acute appendicitis or mechanical obstruction such as intussusception or Meckel's diverticulum. During hospitalization, since we could not rule out surgical abdomen after inconclusive image findings, we closely followed the patient and repeated physical examinations carefully. Eventually surgical exploration was performed based on changes in clinical condition, which proved to be the right decision for the patient. We propose that in children with suspected strangulation of small bowel obstruction, especially when imaging findings do not provide a conclusive diagnosis, the timely exploratory surgical approach ought to be chosen based on carefully observed clinical findings and other evaluations.

In vitro Differentiation of Human Embryonic Stem Cells into Definitive Endodermal Cells / 대한이식학회지

PURPOSE: Whole liver transplantation has limitation including donor shortage and fatal surgical complications. Hepatocyte transplantation, which is simpler and less expensive than whole liver transplantation, allows the use of living related donors, permits the use of a single donor organ for multiple recipients. However, hepatocytes have limitation in proliferation and lose their property during culture period. To over come these problems, here we performed differentiation of human embryonic stem cells (hESCs) into definitive endoderm in order to differentiate into hepatocytes efficiently. METHODS: Undifferentiated hESCs were maintained on mouse embryo fibroblast feeder (MEF) layer for 5~7 days. For endoderm differentiation, we used modified Kevin A D'Amour's method that added 100 ng/mL Activin A for 5 days. After differentiation, differentiated endodermal cells were collected and RT-PCR and immunostain analysis were performed. RESULTS: After 5 days of differentiation period, hES cells showed endoderm committed-cells and increased expression of endoderm-specific marker genes (Sox17 and Foxa2). Also differentiated endoderm cells were stained with Sox17 and Foxa2 whereas undifferentiated hES cells were not stained with Sox17, Foxa2. CONCLUSION: In vitro differentiotion from hES cells to definitive endoderm was done repetitively by our methods. Further well defined protocol for differentiation of definitive endoderm to hepatocytes should be made.

In vitro Differentiation of Human Mesenchymal Stem Cells into Hepatocytes / 대한이식학회지

PURPOSE: Whole liver transplantation has limitation including donor shortage and fatal surgical complications. Hepatocyte transplantation, which is simpler and less expensive than whole liver transplantation, allows the use of living related donors, permits the use of a single donor organ for multiple recipients, and makes possible the cryopreser-vation of hepatocytes for future use. However, hepatocytes have limitation of proliferation and lose their property during culture period. To over come this problems, here we performed differentiation of bone marrow derived mesenchymal stem cells into hepatocytes. METHODS: Human bone marrow cells were harvested from posterior iliac spine of male and then mononuclear cells were obtained by Ficoll-Paque density-gradient centrifuge and plated in tissue culture flasks. For hepatogenic differentiation, we used modified Kuan-Der Lee's method. After differentiation, hepatocytes were collected and RT-PCR and PAS stain analysis were performed. RESULTS: After 5 weeks of cultivation period, mesenchymal stem cells showed cuboidal morphology and contained abundant granules in the cytoplasm. RT-PCR analysis showed increased expression of hepatocyte-specific marker genes (albumin,CK18, PERCK, CPS). Undifferentiated MSCs were not stained with PAS and differentiated hepatocytes from human MSCs stained with PAS indicating that hepatocytes contained glycogen in the cytoplasm. CONCLUSION: Hepatocyte transplantation could be one of the most effective treatments for chronic liver disease. However, hepatocyte has several disadvantages and problems. For alternative cell therapy sources, human bone marrow derived MSCs are considered as transplantable cells. Human MSCs are able to differentiate into functional hepatocytes in vitro and can be a possible cell transplantation source for chronic liver disease patients. Further studies should be done for differentiating human MSCs to hepatocytes in vivo condition.