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Biomedical subjects

S K Lee

Publications and source records attributed to S K Lee.

At least 19 recordsLinked to original sources
PubMed1992

Methane monooxygenase component B and reductase alter the regioselectivity of the hydroxylase component-catalyzed reactions. A novel role for protein-protein interactions in an oxygenase mechanism.

The soluble methane monooxygenase (MMO) system, consisting of reductase, component B, and hydroxylase (MMOH), catalyzes NADH and O2-dependent monooxygenation of many hydrocarbons. MMOH contains 2 mu-(H or R)oxo-bridged dinuclear iron clusters thought to be the sites of catalysis. Although rapid NADH-coupled turnover requires all three protein components, three less complex systems are also functional: System I, NADH, O2, reductase, and MMOH; System II, H2O2 and oxidized MMOH; System III, MMOH reduced nonenzymatically by 2e- and then exposed to O2 (single turnover). All three systems give the same products, suggesting a common reactive oxygen species. However, the distribution of products observed for most substrates that are hydroxylated in more than one position is different for each system. For several of these substrates, addition of component B to Systems I, II, or III causes the product distributions to shift dramatically. These shifts result in identical product distributions for Systems I and III in which MMOH passes through the 2e- reduced state ([Fe(II).Fe(II)]) during catalysis. In contrast, System II (in which MMOH probably does not become reduced) generally gives a unique product distribution. It is proposed that changes in MMOH structure occurring upon diiron cluster reduction and/or component complex formation cause substrates to be presented differently to the activated oxygen species. Kinetic studies show that component B strongly activates System I and, in most cases, strongly deactivates System II. The effect of component B on product distribution of System I (and III) occurs at less than 5% of the MMOH concentration, while nearly stoichiometric concentrations are required to maximize the rate of System I. This shows that component B has at least two roles in catalysis. EPR monitored titration of reduced MMOH ([Fe(II).Fe(II)]) with component B suggests that the effect of substoichiometric component B on product distribution is due to hysteresis in the MMOH conformational changes.

Binding Sites↗
PubMed1992

A rheumatoid factor from a normal individual encoded by VH2 and V kappa II gene segments.

OBJECTIVE: To gain insight into the immunoglobulin variable-region repertoire of anti-IgG antibodies (rheumatoid factors [RF]), we characterized the VH and V kappa gene segments utilized in an IgM-RF-secreting lymphoblastoid cell line (SSH23) isolated from a normal individual. METHODS: The cell line SSH23 was established by Epstein-Barr virus transformation of peripheral blood non-T mononuclear cells. First-strand complementary DNA (cDNA) was generated and used for polymerase chain reaction amplification of the heavy and light chain variable domains. The amplified variable domains were sequenced and compared with an extensive database of germline and cDNA V gene segments. RESULTS: The VH sequence was found to be identical to a previously described fetal VH2 incomplete cDNA and to differ by only 3 nucleotides from a JH proximal germline VH2 gene segment. To our knowledge, this is the first example of a VH2 rheumatoid factor. The V kappa 2-J kappa 4 light chain contains an uncommon 10-amino acid third complementarity-determining region (CDR 3). CONCLUSION: Utilization of preimmune fetal VH gene segments and unusual light chain junctional diversity appear to be features shared by many physiologic and pathologic rheumatoid factors.

Amino Acid Sequence↗
PubMed1992

The immunoglobulin kappa light chain repertoire expressed in the synovium of a patient with rheumatoid arthritis.

OBJECTIVE: To analyze the nature of the B cell response in the synovial tissue of a patient with rheumatoid arthritis (RA). Specifically, we sought to determine if the pattern of immunoglobulin expression was consistent with polyclonal stimulation of B cells or an antigen-driven response. METHODS: We generated an unrestricted complementary DNA (cDNA) library from the diseased synovium of a rheumatoid factor (RF)-positive patient with an 18-year history of RA. A random sample of kappa light chain recombinants was identified, and sequence analysis was performed. The variable domains were compared with an extensive database of germline and cDNA kappa sequences. RESULTS: We found a light chain repertoire enriched for kappa transcripts containing 2 V kappa gene segments (Humkv325 and Humkv328) that are frequently associated with paraproteins expressing RF activity. Kappa variable domains from synovium contained numerous somatic mutations which resulted in frequent replacement of amino acids that encode the classic antigen-binding site. Unexpectedly, many of these kappa transcripts contained non-germline-encoded nucleotides (N regions) at the site of V kappa-J kappa joining. The combination of N-region addition and variation in the sites of V kappa-J kappa splicing generated unusually long complementarity-determining region 3 regions and charged amino acids near the V kappa-J kappa splice site. CONCLUSION: The pattern of somatic mutations found in this patient sample supports the hypothesis that these synovium-derived plasma cells are the product of immunoglobulin receptor-dependent (i.e., antigen-driven) selection. The extent of N-region addition raised the additional possibility that these antibodies derive from an unusual set of B lymphocytes that have escaped normal regulation.

Amino Acid Sequence↗
PubMed1992

MRI of sequela of transverse myelitis.

A 4-year-old boy developed acute paraplegia, associated with sensory impairement and bowel and urinary dysfunction after an URI. MRI showed diffuse hyperintensity in T2WI in the spinal cord below the T6 level. Acute transverse myelitis was diagnosed based on the clinical presentations and MRI findings. The patient had poor recovery and two months later, a follow-up MRI disclosed a severe diffuse atrophic change of the spinal cord in the affected segment.

Acute Disease↗
PubMed1992

Immunoarchitecture of normal human bone marrow: a study of frozen and fixed tissue sections.

To provide baseline information on the immunoarchitecture of normal bone marrow, we studied cryostat-cut, frozen, and paraffin-embedded, fixed tissue sections prepared from 21 core biopsies of normal bone marrow obtained during bone marrow harvests for transplantation. A large panel of antibodies was applied that included, for frozen tissue, Leu-6 (CD1), T11 (CD2), Leu-3a (CD4), Leu-1 (CD5), Leu-2a (CD8), J5 (CD10), My7 (CD13), Leu-11 (CD16), B4 (CD19), B1 (CD20), B2 (CD21), Tac (CD25), My9 (CD33), T200 (CD45), NKH-1 (CD56), kappa and lambda chains, beta F1, Ki-67, HLA-DR, TQ1, and keratin, and for fixed tissue, leukocyte common antigen (CD45), L26 (CD20), LN1 (CDw75), LN2 (CD74), LN3, LN4, LN5, MB1 (CD45R), MB2, MT1 (CD43), MT2 (CD45R), UCHL1 (CD45R0), BM1, Ki-1 (CD30), Leu-M1 (CD15), lysozyme, KP1 (CD68), actin, S100, neuron-specific enolase, vimentin, and keratin. On fresh-frozen sections CD19 and CD2 were the most reliable and sensitive markers for B and T cells, staining 5% and 9% of marrow cells, respectively. Immunoglobulins generally showed heavy background staining, which frequently precluded an accurate assessment. The CD4 to CD8 ratio in the bone marrow was reversed from that of peripheral blood. On fixed tissues, leukocyte common antigen was found in 14% of the marrow cells, corresponding roughly to the lymphocyte population. L26, a pan-B-cell marker, stained 3% of the marrow cells. Among the other B-cell markers, LN1 and MB2 stained a large number of cells (40% to 70%), indicating reactivity with cells of the myeloid or erythroid series in addition to lymphocytes. Among the T-cell markers, UCHL1 and MT1 stained 66% and 50% of the cells, respectively, which could be explained by their cross-reactivity with myeloid cells. Nonspecific myelomonocytic markers (Leu-M1, KP1, and lysozyme) also showed reactivity in a high percentage of cells. No particular architectural distribution patterns of B or T lymphocytes were noted in either frozen or fixed bone marrow specimens. The results of this study provide normal baseline data for the immunohistologic application of hematopoietic and lymphoid markers on frozen or fixed bone marrow biopsy specimens.

Adult↗
PubMed1992

HLA-DR expression in human fetal thymocytes.

We analyzed the expression of MHC class I (W6/32) and class II (HLA-DR) antigens on human fetal and postnatal thymocytes by fluorescence-activated cell sorting. Less than 5% of prenatal thymocytes expressed HLA-DR before week 12 of gestation. However, the number of HLA-DR-positive cells significantly increased during the late second and third trimester of gestation, when greater than 50% of prenatal thymocytes expressed HLA-DR. Such high-level expressions of HLA-DR in fetal thymocytes were also demonstrated by Northern-blot analysis and immunohistochemistry. After birth, the percentage of HLA-DR-positive cells in thymocytes decreased gradually. A high-level expression of class I antigen was also observed in thymocytes from the early stages of gestation, but, in contrast to MHC class II, a majority of postnatal thymocytes maintained high levels of class I antigen after birth.

Cell Separation↗
PubMed1992

Prenatal growth pattern of the human maxilla.

Regarding maxillofacial morphogenesis there has been a long debate on the growth of the maxillary structure. Using 120 normal fetal maxillae of gestational ages from 16 to 41 weeks, palatal radiograms and frontal histologic sections were made. We have observed two pairs of accentuated growth areas in the fetal maxillae and named them primary growth centers to formulate the maxillary trapezoid (MT) by radiologic image. The MT is formed by four primary growth centers that are best demonstrated by palatal radiograms of the fetal maxilla as well as by frontal histologic sections. The dimensional increase in the MT during the fetal period is documented and statistically analyzed. From this series of results, we have suggested that the growth centers which demarcate the MT are the basic structures of the developing human maxilla. It was also found that the four primary growth centers are the most active sites for maxilla formation until 20 weeks of gestation and thereafter the growth of the maxilla is enhanced by the participation of the intramembranous bone formation along the periphery. This was in contrast to the central primary growth centers that have already finished maturation in the early fetal period and remain only as a peripherally radiating arrangement of thick trabecular bones.

Bone Development↗
PubMed1992

POEMS syndrome--a case report.

POEMS syndrome is a multisystem disorder associated with polyneuropathy, organomegaly, endocrinopathy, a monoclonal protein (M-protein), and skin changes. The authors describe a patient with POEMS syndrome who had osteosclerotic myeloma confirmed by open bone biopsy. Magnetic resonance imaging (MRI) showed discrete lesions of low signal intensity in both T1 and T2-weighted images. This patient is now being successfully treated with melphalan and prednisone with much improvement in skin thickening and sensory change in the lower extremities.

Adult↗
PubMed1992

A monoclonal antibody to common acute lymphoblastic leukemia antigen (CALLA) and its expression on several human tumor cell lines.

We describe a newly-made murine monoclonal antibody to the common acute lymphoblastic leukemia antigen (CALLA), named SHB-10. The antigen detected by SHB-10 has a molecular weight of about 105 kDa. This antibody is very similar to that of conventional anti-CD10 Ab on indirect flowcytometric analysis using lymphoid malignant cell lines and peripheral lymphocytes of acute lymphoblastic leukemia (ALL) patients. The binding of anti-CD10 to Daudi cell and peripheral lymphocytes of ALL patients is blocked by SHB-10. Thus this monoclonal antibody is thought to detect the CALLA. The distribution of antigen detected by SHB-10 on several cell lines of neuroectodermal tumor and lymphoid malignancy was analysed and a slight difference in their cell surface expression is observed when compared with that by conventional anti-CD10. Further biochemical analysis is now under way for a better characterization of this antigen.

Animals↗
PubMed1992

Extracorporeal shockwave lithotripsy of primary intrahepatic stones.

Extracorporeal shockwave lithothripsy (ESWL) was performed in intrahepatic stone patients (n = 18) by Dornier MPL 9,000 with ultrasound guidance. The patients had T-tube (n = 9) or percutaneous transhepatic biliary drainage tube (n = 9). Average treatment session was four and shock-wave numbers were in the range of 3,064 to 12,000 (average 6,288 shocks). Intrahepatic stones were removed completely in 16 patients over a 3 month period by ESWL and combined stone extraction maneuver such as cholangioscopic or interventional radiologic method. Extracorporeal shockwave lithothripsy was very helpful in facilitating extraction of stones in unfavorable locations or located above the severe stricture. In summary, extracorporeal shockwave lithotripsy, followed by percutaneous stone extraction, will provide an improvement in the success rate and duration of treatment required for complete removal of primary hepatolithiasis.

Bile Ducts, Intrahepatic↗
PubMed1992

[Differentiation between primary hepatocellular carcinoma and hemangioma on MRI].

Most of the primary hepatocellular carcinoma and hemangioma in TIWI are having low signals. Hemangioma is relatively lower in signal intensity than primary hepatocellular carcinoma, but they are really no so easy compare by bare eye. On the contrary, in T2WI, hemangioma is more brighter than primary hepatocellular carcinoma. So, by compare the variety shows from T1WI to T2WI, we can differentiated between primary hepatocellular carcinoma and hemangioma. By measuring the signal intensity in non-tumor area, there are no marked different in T1WI and T2WI, but hemangioma, as compare with primary hepatocellular carcinoma in signal intensity, is lower in T1WI and much higher in T2WI. Such results are all having statistic significant with p value less than 0.05. In measuring the different in signal intensity or ratio between tumor and non-tumor areas, there were mark different in T2WI and whereas there were no different in T1WI. By using two-point method, the T2-relaxation is measured in twenty eight cases of primary hepatocellular carcinoma and thirteen cases (twenty four lesions) of hemangioma. We found that there were nearly equal in nontumor areas, but there were mark different in T2-relaxation. In comparison with intravenous injection of Gd-DTPA in 10 cases of primary hepatocellular carcinoma and six cases of hemangioma, the latter were having similar dynamic CT appearance. Enhancement of signal intensity was found starting from peripheral part to central area. The primary hepatocellular carcinoma were having none of the above phenomenon. The liver MRI study is still expensive and time consuming.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1992

[MRI of adrenal tumors].

Within a two and half years period, we collected a total of twenty three cases of adrenal tumors diagnosed by MRI. They included: one cystic case, twelve cases (13 lesions) of adenoma, two cases (3 lesions) of hyperplasia, four cases of pheochromocytoma, three cases of metastases, and one case of adenocarcinoma. Except for the case of adrenal cyst which was followed for one and a half years, all the other twenty two cases were proved by operation and pathology. The benign adenoma and hyperplasia were small in size, and had relative isointensities to the liver in the T1WI and the T2WI. On the contrary, the malignant tumors and pheochromocytoma, all had inhomogeneous signal intensities, showed relatively lower in signal intensities in T1WI and higher in T2WI as compared with the liver. In T2WI, the tumor to liver signal intensity ratio of adenoma and hyperplasia were less than 1.80, whereas the malignant tumors and pheochromocytoma were larger than 1.80. In comparing fifteen cases with Gd-DTPA intravenous injection, all of the benign adenoma did not show an increase in signal intensity, but the malignant tumors and pheochromocytoma showed increase in signal intensity. We concluded that we could primarily differentiate the nature of adrenal tumors by their change in signal intensities between T1WI and T2WI, by measuring the tumor to liver signal intensity ratio or by Gd-DTPA IV injection. Today, although adrenal gland MRI examination is more time consuming and expensive, it is more valuable for highly clinically suspected adrenal lesions with equivocal results after CT or sonogram study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1992

[Intracranial germ cell tumors].

We report on 19 cases of intracranial germ cell tumors, including 12 male and 7 female patients; the average age was 16.5 +/- 4.9 years. These tumors included germinoma in 15 cases, yolk sac tumor in 3 cases, embryonal cell carcinoma in 1 case, and mixed tumor in 3 cases. Each of 5 cases had 2 to 3 different kinds of tumor cells, either in one tumor or in different tumors. The locations of tumors were pineal region in 13 cases, suprasellar region in 3 cases, basal ganglion-thalamus in 3 cases, and cerebral hemispheres in 4 cases. Six of them had 2 or more locations. One case had spinal seeding and extraneural metastasis to the liver, retroperitoneum and neck lymph nodes. Eighteen cases received CT scan and 6 cases received MRI examinations, all the tumors had good enhancement by iodium content contrast medium in CT and Gadolinium-DTPA in MRI. Alfa-fetoprotein was elevated in yolk sac tumor, AFT and HCG were elevated only slightly or remained normal in germinoma. Germinomas had good response to radiation therapy and chemotherapy, while nongerminoma had poor response and worse prognosis.

Adolescent↗
PubMed1992

Clinical application of ejection fraction by gated MRI.

To evaluate the clinical desired accuracy of the left ventricular ejection fractions (EFs) calculated by magnetic resonance imaging (MRI). Within one to three days post coronary angiography and left ventriculogram, twenty-five adults were studied by MR imaging. They had nuclear medicine studies for left ventricular ejection fractions as well. EKG-gated spin-echo 30-msec echo-delay images were obtained in end systole and end diastole in a plane parallel to the ventricular septum. Analysis of ventricular volumes and ejection fractions were performed using the area-length method. The EFs calculation by gated MRI were compared with that obtained by angiocardiography and nuclear medicine studies. The linear regression line obtained for ejection fraction was y = 0.858x +6.813, r = 0.753, p = 0.009; y' = 1.567x'-24.692, r' = 0.783, p' = 0.002. The above figure indicate a reasonable correlation among these three methods.

Humans↗
PubMed1992

[Detection of the myelination process of Chinese infants by 1.0T MRI].

To establish the myelination process of brain of Chinese infants, our study consisted of seventy-five infants ranging in age from 5 days to 2 years old. They were studied with a 1.0 T superconductive MRI. In the new born, myelination could be seen in the brainstem, middle cerebellar peduncle, and posterior limb of the internal capsule in both T1WI and T2WI. Then the myelination process rapidly progressed month by month. Myelination of the centrum semiovale and optic radiation could be seen in T1WI in the newborn up to 3 months old, and in T2WI at 3-5 months old. The myelination of the splenium and the genu of corpus callosum were seen at 3-6 months in T1WI and 5-6 months in T2WI. Myelination of the occipital lobe and frontal lobe were seen at 3-6 months and 5-10 months in T1WI, and 8-14 months, 10-16 months in T2WI respectively. In 7-10 months, the brain appeared as an "early adult pattern" in T1WI; while, in T2WI, the brain appeared as an "early adult pattern" at 14-18 months old. The understanding of the myelination process in infants is important and essential for the judgement of the infantile brain and for the diagnosis of many CNS diseases of infants.

Age Factors↗