Biomedical subjects

Wonbae Lee

Publications and source records attributed to Wonbae Lee.

6 recordsLinked to original sources

PubMed2005

Surface functional group effect on atomic force microscope anodization lithography.

The lithographic effect of surface chemical functional groups of organic resists on atomic force microscope (AFM) anodization lithography is investigated using mixed self-assembled monolayers (SAMs). The SAM resist films were prepared with 1,12-diaminododecane dihydrochloride (DAD.2HCl), n-tridecylamine hydrochloride (TDA.HCl), and 1,12-diaminododecane hydrochloride (DAD.HCl), and their film characteristics were evaluated by ellipsometry, zeta-potential measurements, and AFM. The lithographic results indicate that the most dominant factor of the surface functional group effect is the electrochemical property of the surface groups as an anode surface in the anodization reaction, and the dimensions of the protruded patterns are critically determined by the wetting property of the resist surface. By controlling the surface chemical groups with considerations of their effects, high-speed patterning at 2 mm/s was achieved successfully using the mixed SAM resist of DAD.2HCl and TDA.HCl.

Journal Article↗

PubMed2005

Significance of cerebrospinal fluid sIL-2R level as a marker of CNS involvement in acute lymphoblastic leukemia.

Soluble IL-2 receptor (sIL-2R), total protein, uric acid, glucose, aspartate aminotransferase (AST) and lactate dehydrogenase (LD) levels were analyzed in 153 (19 cytology(+), 134 cytology(-)) pairs of CSF and serum samples and the data were compared with the results of cytologic examination to find new CSF markers of CNS involvement in 77 patients with acute lymphoblastic leukemia (ALL). The CSF leukocyte count of cytology(+) samples averaged 107.6+/-362.4 cells/microl, and was higher than that of cytology(-) samples (1.0+/-3.4 cells/microl, p=0.001). The CSF sIL2-R level of cytology(+) samples averaged 162.1+/-247.7 U/ml, and was higher than that of cytology(-) samples (11.2+/-44.6 U/ml, p <0.001). The CSF total protein, uric acid, glucose, AST, and LD levels were not significantly different in cytology(+) and cytology(-) samples (p >0.05). ROC curves showed that the discrimination power of CSF sIL2-R for the presence of leukemic blasts was better than that of CSF leukocyte counts. With a cut-off value for CSF sIL2-R at 10 U/ml, the sensitivity was 89.5% and the specificity was 89.6%. With a cut-off value for CSF leukocyte count at 4 cells/microl, the sensitivity and specificity were 47.4% and 63.2%, respectively. In conclusion, CSF sIL2-R level is a valuable marker of CNS involvement in ALL patients; a level of >10 U/ml may serve as an objective indicator of CNS involvement in conjunction with conventional cytology and the CSF leukocyte count.

Biomarkers, Tumor↗

PubMed2003

Gastrointestinal tract cancer screening using fecal carcinoembryonic antigen.

There is a great need to detect gastrointestinal tract cancer at an early stage. It is well known that most carcinoma tissues of the gastrointestinal tract contain carcinoembryonic antigen (CEA). Stools are a rich source of cells derived from the gastrointestinal tract. We analyzed total fecal CEA in 60 gastrointestinal tract cancer patients, 20 benign gastrointestinal tract disorder patients, and 240 normal controls, using a simple, reliable method. We compared the sensitivity and specificity of fecal CEA with those of serum CEA and fecal occult blood test (FOBT). The level of fecal CEA in gastrointestinal tract cancer was much higher than controls (44.1 +/- 70.1 ng/mg stool vs 3.7 +/- 3.5 ng/mg stool, p < 0.001) and was not increased in benign gastrointestinal disorders (4.5 +/- 8.2 ng/mg stool). Fecal CEA level was > 10 ng/mg stool in 22 of 32 samples (69%)from stomach cancer patients and 24 of 28 samples (86%)from colorectal cancer patients. The sensitivity of serum CEA (> 5 ng/ml) was 19% in stomach cancer and 39% in colorectal cancer, whereas the sensitivity of FOBT was 13% in stomach cancer and 21% in colorectal cancer. The specificity of fecal CEA was 90% in benign gastrointestinal tract disorders and 93% in normal controls. This specificity was similar to those of serum CEA and FOBT. In conclusion, fecal CEA measurement is superior to serum CEA or FOBT for detection of gastrointestinal tract cancer. Fecal CEA may become the screening test of choice for gastrointestinal tract cancer.

Adult↗

PubMed2002

Quantities of receptor molecules for colony stimulating factors on leukocytes in measles.

We analyzed the comparative amounts of granulocyte-colony stimulating factor (G-CSFr) and granulocyte macrophage CSF (GM-CSFr) receptors expressed on neutrophils and monocytes in measles patients to investigate the role of these CSFrs in the development of leukopenia including neutropenia and monocytopenia in measles. EDTA-anticoagulated peripheral blood of 19 measles patients, 10 children with other infections showing leukopenia and 16 children with normal complete blood cell counts (CBC)s were analyzed using flow cytometry and QuantiBRITE. The leukocyte (5260 +/- 2030/uL vs. 9900 + 2680/uL, p=0.000), neutrophil (2580 +/- 960/uL vs. 4250 +/- 2750/uL, p=0.024) and the lymphocyte counts of measles patients (1810 +/- 1430/uL vs. 4530 +/- 3450/uL, p= 0.006) were lower than in the normal controls. The neutrophils of measles patients expressed similar amounts of G- CSFr (1858 +/- 355) as normal children (1764 +/- 477, p= 0.564) and leukopenic patients (1773 +/- 673, p=0.713), but lower levels of GM-CSFr (535 +/- 118) than normal children (957 +/- 344, p=0.000) and leukopenic patients (832 +/- 294, p=0.002). The monocytes of measles patients expressed similar amounts of G-CSFr (916 +/- 336) and GM-CSFr (3718 +/- 906) as normal children (1013 +/- 391 and 4125 (2645, p > 0.05) but less than leukopenic patients (1454 +/- 398 and 5388 +/- 806, p > 0.05). The neutrophil and monocyte counts of measles patients did not correlate with the amount of G-CSFr or GM-CSFr expressed on neutrophils or monocytes (p > 0.05), but in the normal children, the monocyte count correlated with the levels of GM-CSFr on monocytes (r=0.951, p=0.049). In conclusion, neutropenia is one of the more important characteristics of measles patients, which could be due to the decreased GM-CSFr expression on neutrophils. However, the monocytopenia found in measles patients is not due to the decreased expression of CSFr on the monocytes.

Humans↗

PubMed2002

Rapid, sensitive diagnosis of hemolytic anemia using antihemoglobin antibody in hypotonic solution.

We have developed a new and simple flow cytometric method to detect damaged red blood cells (RBCs) using anti-Hb in hypotonic solution. We studied a total of 200 patients, including 62 patients with schistocytosis, 8 postsplenectomy patients, and 108 healthy controls. Peripheral blood (2 microl) was stained with phycoerythrin-conjugated (PE) antihemoglobin antibody (anti-Hb) in 0.6% (w/v) NaCl solution, and analyzed by flow cytometry omitting the washing step. The proportion of RBCs stained by anti-Hb was 0.55% (SD +/-0.23%) in normal controls and was significantly higher in patients with schistocytosis (2.95+/-2.95%, p <0.001). Six of 108 blood samples from normal controls and 60 of 62 samples from schistocytosis patients showed > or =1.01% stained RBCs (ie, values > mean+2SD of normal controls). The number of schistocytes counted by microscopic examination correlated with the proportion of RBCs stained by anti-Hb (r = 0.637, p <0.001). The proportions of stained RBCs in blood samples with malaria, spherocytosis, and elliptocytosis were also significantly higher than in normal controls. However, the results in postsplenectomy and iron-deficiency anemia (IDA) patients were not significantly different from the normal controls; the number of schistocytes in postsplenectomy patients was not related to the proportion of RBCs stained by anti-Hb. Based on these findings, flow cytometry of damaged RBCs using anti-Hb in hypotonic solution is a simple, sensitive, and accurate method to detect active hemolysis.

Anemia, Hemolytic↗

PubMed2002

Evaluation of early post-transplant leukocyte recovery using the undiluted erythrocyte lysing technique.

The undiluted erythrocyte lysing technique was evaluated to see if it provides more accurate total leukocyte counts and differential leukocyte counts of severely leukopenic blood samples, in order to detect the onset of hematopoietic recovery after stem cell transplantation. Leukocyte counts using the conventional automated cell counting technique were found to be inaccurate, especially in blood samples with total leukocyte counts < 500/microl. In cases where the difference between results by the two methods was >100/microl, a positive correlation was found between the difference value and the blood reticulocyte count (r = 0.39, p = 0.002). Hematopoietic recovery after stem cell transplantation in a group of patients with chronic myelogenous leukemia (CML) was different from that of non-CML groups. In the CML group, the initial leukocyte counts were higher and the number of days until neutrophil recovery was higher than in the non-CML groups. Also, the day on which the absolute neutrophil count (ANC) exceeds 100/microl could serve as an indicator of neutrophil recovery. This study shows that the undiluted erythrocyte lysing technique can be used to count leukocytes accurately, especially in severely leukopenic samples. This new method can detect neutrophil recovery at ANC > 100/microl, as well as at an earlier date than the conventional method.

Erythrocytes↗