Human stem cells have been isolated from embryos as well as diverse somatic tissues. Much efforts have been made to apply those stem cells for therapeutic purpose. Molecular dissection of "stemness" and differentiation process will provide us a clue to further understanding of stem cell biology. The fate of stem cell is determined in part by internal regulation mediated by transcriptional control. A set of genes related to specific functions might be expressed and suppressed upon external or internal signaling. Therefore, it is necessary to identify the complete gene expression profile that defines the stem cell. Moreover, we should verify the potential of therapeutic stem cells regarding differentiation, specific function, tumorigenecity, and toxicity rigorously before the clinical application. At present we have only limited information on "stemness" and differentiation into specific lineages. In the genome era, we can draw a molecular portrait on these functional and morphologic changes along the differentiation, trans-differentiation as well as de-differentiation using the DNA chip technology. We need to accumulate database for gene expression at various steps of stem cell differentiation, which will enhance our knowledge for research on and medical application of stem cell.
Biology ; Embryonic Structures ; Gene Expression ; Gene Expression Profiling ; Genome ; Genomics ; Humans ; Oligonucleotide Array Sequence Analysis ; Stem Cells* ; Transcriptome

The ideal restorative material should mimic the properties of the tissues it replaces. Dental composite resins have been used widely as restorative materials due to its advantages such as excellent esthetics and ease of manipulation. But inadequate wear resistance has been a major factor limiting the use of composite restorative materials. Improved manufacturing techniques have allowed the development of hybrid composites, with a greater percentage volume filler loading, which have improved physical an mechanical properties. However they are lacking the study wear resistance. The purpose of this study was to evaluate the wear of human enamel against ceromer by the use of a pin-on-disk type wear testers. Discs of ceromer(Targis : Ivoclar, Vivadent, Amherst. NY) and discs of type III gold alloy as a control were used for test specimens. Intact cusp of premolar and molar were used for enamel specimens. The wear of enamel was determined by weighing the cusp before and after each test, and the weight converted to volumes by average density of enamel. Surface profilometer was used to quantify wear of the ceromer and gold specimens. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows; 1. Ceromer produced less enamel wear than gold(p<0.05). 2. The wear volume of ceromer was greater than that of gold(p<0.01). 3. The hardess of ceromer was lower than that of gold, but there was no correlation between the hardness and wear of the ceromer and gold. 4. SEM analysis revealed that there were many voids and microcracks in the wear tract of ceromer. in gold group, many minute V-shaped grooves were examined.
Alloys ; Bicuspid ; Composite Resins ; Dental Enamel* ; Esthetics ; Hardness ; Hardness Tests ; Humans* ; Molar

No abstract available.

OBJECTIVE: The accuracy of analytical results of blood and urine heavy metals came out to the main issue on occupational health from late eighties. The discrepancy of the results for same samples from different laboratories made the diagnosis for occupational diseases be unreliable. Therefore, a quality control program for analysis of samples taken from workplace had been introduced in Korea since 1992. This study aims to show the quality control program f'or analysis of blood and urine samples and its proficient rates from 1992 to 1999 and to know how they have been being used in occupational health. METHODS: The quality control program runs twice a year with mandatory items of blood lead and urine hippuvic acid and voluntary items of blood cadmium and manganese and urine mandellic acid and methyl hippuric acid. Participant laboratories are receiving three levels for each items and two out of three samples have to be qualified for being a proficient laboratory for the item. The acceptable range of blood lead and urine hippuric acid is +/-15% and that of the others is within 3 SD(standard deviation) from the reference values. RESULTS: The proficient rates of blood lead and urine hippuric acid was 89%, 90%, repectively, however those of the other voluntary items have been from 51% to 62%. The proficient rates of urine mercury and urine N-methylformamide(NMF), which are introduced since 1999, were very poor. Urine hippuric acid and blood lead were analyzed frequently for the purpose of biological monitoring conducting by special health examination organizations. Urine and blood manganese and urine metabolites of trichloroethylene, urine phenol, methylhippuric acid and cadmium were followed. CONCLUSIONS: In conclusion, the quality control program for biological monitoring has dramatically improve the ability of analysing blood and urine samples and eventually contributes to diagnose occupational diseases and to prevent occupational poisoning. However, some biological monitoring data, such as urine manganese, mercury and NMF, have been still reported from laboratories that were not accepted as a proficient laboratory.
Cadmium ; Diagnosis ; Environmental Monitoring ; Korea ; Manganese ; Metals, Heavy ; Occupational Diseases ; Occupational Health ; Phenol ; Poisoning ; Quality Control ; Reference Values ; Trichloroethylene

BACKGROUND: CD34 positive cell enumeration by flow cytometry is currently used to determine the optimal timing of peripheral blood stem cell collections (PBSC) and to predict engraftment of stem cell transplantation. However, the technical problems and lack of a standardized method are sources of significant variability in the quantitation of the CD34 positive cells. ProCOUNT(TM) (Beckon Dickinson Immuno- cytometry System, USA) kit for three color flow cytometric analysis was introduced to enumerate CD34 positive cells using a standardized method. This study was conducted to evaluate the usefulness of the three color method, ProCOUNT(TM), in comparison with two color method. METHODS: CD34 positive cells from 25 cord blood samples were enumerated by two methods, two color (CD34-PE/CD45-FITC) and three color (ProCOUNT(TM) , nucleic acid dye/CD34-PE/ CD45-PerCP) flow cytometric analysis, in which CD34 positive cells were counted directly in comparison with counting beads introduced in the sample. RESULTS: The count of CD34 positive cells in the cord blood was 28.3(+/-20.0)/uL and 20.9 (+/-16.0) /uL by three color and two color methods, respectively, The number of CD34 positive cells enumerated by ProCOUNTTM kit was well correlated with that by two color method, but the count was significantly higher in the former method (p<0.01). CONCLUSIONS: In the three color method, loss of stem cells was significantly lower than that in the two color method, and it was possible to obtain a direct count of CD34 positive cells by using a standardized procedure.
Fetal Blood* ; Flow Cytometry ; Hematopoietic Stem Cells* ; Stem Cell Transplantation ; Stem Cells

BACKGROUND: CD34 positive cell enumeration by flow cytometry is currently used to determine the optimal timing of peripheral blood stem cell collections (PBSC) and to predict engraftment of stem cell transplantation. However, the technical problems and lack of a standardized method are sources of significant variability in the quantitation of the CD34 positive cells. ProCOUNT(TM) (Beckon Dickinson Immuno- cytometry System, USA) kit for three color flow cytometric analysis was introduced to enumerate CD34 positive cells using a standardized method. This study was conducted to evaluate the usefulness of the three color method, ProCOUNT(TM), in comparison with two color method. METHODS: CD34 positive cells from 25 cord blood samples were enumerated by two methods, two color (CD34-PE/CD45-FITC) and three color (ProCOUNT(TM) , nucleic acid dye/CD34-PE/ CD45-PerCP) flow cytometric analysis, in which CD34 positive cells were counted directly in comparison with counting beads introduced in the sample. RESULTS: The count of CD34 positive cells in the cord blood was 28.3(+/-20.0)/uL and 20.9 (+/-16.0) /uL by three color and two color methods, respectively, The number of CD34 positive cells enumerated by ProCOUNTTM kit was well correlated with that by two color method, but the count was significantly higher in the former method (p<0.01). CONCLUSIONS: In the three color method, loss of stem cells was significantly lower than that in the two color method, and it was possible to obtain a direct count of CD34 positive cells by using a standardized procedure.
Fetal Blood* ; Flow Cytometry ; Hematopoietic Stem Cells* ; Stem Cell Transplantation ; Stem Cells

OBJECTIVE: This study was performed to evaluate the effect of cervical cerclage and the clinical characteristics in incompetent internal os of the cervix (IIOC). METHODS: A study was conducted on 170 patients with IIOC, 199 cases of IIOC were admitted and treated with McDonald operation or modified Shirodkar operation at department of Obstetrics and Gynecology Il Sin Christian Hospital from January 1. 1994 to December 31. 1998, of this 14 cases were follow up lost, so 185 cases were analyzed. RESULTS: 1) The incidence of IIOC was 0.43%, 1 in 233 deliveries. 2) The mean age of IIOC patients was 30.54yrs old and the most frequent age group was in 30-34yrs old group (43.78%). 3) The average number of gravida and parity before operation were 4.71 and 1.62. & the success rate of operation was low at high gravida & parity. 4) The predisposing factor was previous history of dilation & curettage (43.75%), Cx. laceration after delivery (6.49%), midtrimester termination (4.32%) etc. 5) The operation methods were McDonald operation (91.35%) and modified Shirodkar operation (8.65%) & the success rate of McDonald operation and modified Shirodkar operation were 85.80% and 87.50%. 6) The successful fetal salvage rate was 85.95% and the highest success rate was 87.50% in 14-16 weeks of gestation group. 7) The more cervix dilate, the more failure occurred. 8) The causes of operation failure were premature rupture of membrane (50.00%), preterm labor (34.62%), FDIU, anomaly, APH etc. 9) The delivery methods after operation were vaginal delivery (65.54%), cesarean delivery (34.46%). CONCLUSION: The 14-16th weeks of gestation group & no cervical dilatation have higher success rate indicating that early diagnosis and appropriate timing of operation is associated with a greater operation success rate.
Causality ; Cerclage, Cervical ; Cervix Uteri* ; Curettage ; Early Diagnosis ; Female ; Follow-Up Studies ; Gynecology ; Humans ; Incidence ; Labor Stage, First ; Lacerations ; Membranes ; Obstetric Labor, Premature ; Obstetrics ; Parity ; Pregnancy ; Pregnancy Trimester, Second ; Rupture

OBJECTIVE: The goal of this study is to determine the efficacy of rapid karyotyping from fetal ascitic fluid. METHODS: In three cases of isolated fetal ascites diagnosed by prenatal ultrasonography, ultrasound guided fetal paracentesis and amniocentesis were performed and successfully obtained. Fetal karyotyping in each case at 29, 30 and 32 weeks gestation using modified lymphocyte culture method was conducted. RESULTS: The chromosomal analysis was successful within 72 hours and abnormalities were detected in two cases and revealed trisomy 21 in each case. Our study demonstrated that the majority distribution of white blood cells was lymphocytes which ranged from 2.1 * 10(6) cells/ml to 3.7 * 10(6) cells/ml and the cell density for culture was at least than 0.35 * 10(6) cells/ml. CONCLUSION: The use of ascitic fluid as a cell source to achieve rapid fetal karyotyping can be valuable when cordocenteis or amniocentesis would be technically more difficult, or when rapid result is required for planning of perinatal management at late second or third trimester gestational age.
Amniocentesis ; Ascites ; Ascitic Fluid* ; Cell Count ; Cytogenetics* ; Diagnosis* ; Down Syndrome ; Female ; Gestational Age ; Humans ; Karyotyping ; Leukocytes ; Lymphocytes ; Paracentesis ; Pregnancy ; Pregnancy Trimester, Third ; Ultrasonography ; Ultrasonography, Prenatal

In 10 cases with intracranial arterivenous malformation (AVMs) diagnosed by MR spin echo images, MR angiography was evaluated and compared with conventional angiography in regard to depiction of nidus, arterial feeders, and draining veins. Spin echo images demonstrated the nidus of the AVM in all cases, but displayed the feeding vassels inadequately. These vessels were directly visualized with 3 dimensional STAGE(small tip angle gradient echo) MR angiography using rephasing/dephasing pulse sequences. In 5 cases MR angiography and conventional angiography showed the same results. However, in the others, MR angiography showed lower resolution than conventional angiography. MR angiography is useful in preangiographic evaluation of intracranial AVM but improvement in image resolution, which is dependent on MR hard ware and pulse sequence, is still to be desired.
Angiography* ; Intracranial Arteriovenous Malformations* ; Veins

No Abstract Available.