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T J Kim

Publications and source records attributed to T J Kim.

At least 37 records · Page 2Linked to original sources
PubMed2000

Differential activation of MAP kinase family members triggered by CD99 engagement.

The molecular basis for the modulatory properties of CD99 is not well understood. Treatment of human Jurkat T lymphocytes with anti-CD99 antibody led to activation of three mitogen-activated protein kinase (MAPK) members, ERK, JNK, and p38 MAPK, along with homotypic aggregation. While phosphorylation of ERK and JNK was inhibited by the pretreatment of a PKC inhibitor, bisindolylmaleimide I, activation of p38 MAPK was upregulated by the same pretreatment. The signaling pathways to MAPKs by CD99 engagement were independent of PI-3 kinase, distinguishing from those by CD3 engagement. Among MAPKs, ERK pathway was essential for homotypic aggregation together with intracytoplasmic Ca(2+).

Antibodies, Monoclonal↗
PubMed2000

Kinetics and inhibition of cyclomaltodextrinase from alkalophilic Bacillus sp. I-5.

The cyclomaltodextrinase from alkalophilic Bacillus sp. I-5 (CDase I-5) was expressed in Escherichia coli and the purified enzyme was used for characterization of the enzyme action. The hydrolysis products were monitored by both HPLC and high-performance ion chromatography analysis that enable the kinetic analysis of the cyclomaltodextrin (CD)-degrading reaction. Analysis of the kinetics of cyclomaltodextrin hydrolysis by CDase I-5 indicated that ring-opening of the cyclomaltodextrin was the major limiting step and that CDase I-5 preferentially degraded the linear maltodextrin chain by removing the maltose unit. The substrate binding affinity of the enzyme was almost same for those of cyclomaltodextrins while the rate of ring-opening was the fastest for cyclomaltoheptaose. Acarbose and methyl 6-amino-6-deoxy-alpha-d-glucopyranoside were relatively strong competitive inhibitors with K(i) values of 1.24 x 10(-3) and 8.44 x 10(-1) mM, respectively. Both inhibitors are likely to inhibit the ring-opening step of the CD degradation reaction.

Acarbose↗
PubMed2000

Endothelium-dependent vasorelaxant and antiproliferative effects of apigenin.

This study was designed to determine whether the relaxant effect of apigenin was endothelium dependent and to examine the possible antiproliferative effect of apigenin. Apigenin relaxed the phenylephrine-precontracted endothelium-intact aortic rings with IC(50) value of 3.7+/-0.5 microM and removal of a functional endothelium significantly attenuated this relaxation (IC(50)=8.2+/-0.9 microM). However, apigenin did not affect the 0.1 microM phorbol 12,13-dibutyrate-induced contraction (IC(50)=34.6+/-1.2 microM) within the concentration range that relaxed the phenylephrine-contracted arteries, suggesting that apigenin did not influence protein kinase C-mediated contractile mechanisms in rat aorta. Pretreatment of apigenin significantly potentiated the relaxant effect of acetylcholine on phenylephrine-induced contraction. Pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME) or methylene blue reduced the relaxant effect of apigenin. Apigenin (10 microM) increased the guanosine 3',5'-cyclic monophosphate (cGMP) content of endothelium-intact tissues. Pretreatment with L-NAME (100 microM) or removal of endothelium significantly suppressed the effect of apigenin on cGMP production. In addition, apigenin significantly inhibited [3H]thymidine incorporation into DNA of primary cultured rat aortic smooth muscle cell in a dose-dependent manner. These findings suggest that besides influx and release of Ca(2+), nitric oxide (NO) and cGMP may account for the apigenin-induced endothelium-dependent relaxation and hypotensive activity. Both vasorelaxant and antiproliferative activities may contribute to a benefit of apigenin in the vascular system.

Animals↗
PubMed2000

Cerebral hemodynamics after exogenous surfactant administration for respiratory distress syndrome in piglet model.

OBJECTIVE: The rapid improvement of lung function after exogenous surfactant treatment for respiratory distress syndrome (RDS) can affect the functions of several other systems, which includes cerebral blood flow volume (CBF). To evaluate the change in CBF after treatment with exogenous surfactant, we measured CBF in a newborn piglet model with RDS. METHOD: After the lung lavage with normal saline, ten animals under mechanical ventilation were administered either 120 mg/kg surfactant-TA (Surfacten) or air placebo. Heart rate, blood pressure, dynamic lung compliance (Cdyn), PaO2, PaCO2, and CBF were recorded before and every 15 min after surfactant treatment up to 120 min. RESULTS: Cdyn was improved significantly at 45 min and later after treatment; that of the control group remained unchanged. PaO2 increased and PaCO2 decreased significantly after surfactant treatment in both groups. However, the improvement was significantly less in the control group. CBF significantly decreased by about 30% in the control group, and by about 50% in the treated group at 120 min, with a significant difference between groups. Almost 70% of the changes in CBF were attributable to changes in PaCO2 by multivariate regression analysis. CONCLUSIONS: Treatment with exogenous surfactant improves lung compliance, and has little effect on CBF itself. The drop in levels of PaCO2 after treatment, however, had a strong relationship with decreases in CBF.

Animals↗
PubMed1999

Crystal structure of a maltogenic amylase provides insights into a catalytic versatility.

Amylases catalyze the hydrolysis of starch material and play central roles in carbohydrate metabolism. Compared with many different amylases that are able to hydrolyze only alpha-D-(1,4)-glycosidic bonds, maltogenic amylases exhibit catalytic versatility: hydrolysis of alpha-D-(1,4)- and alpha-D-(1,6)-glycosidic bonds and transglycosylation of oligosaccharides to C3-, C4-, or C6-hydroxyl groups of various acceptor mono- or disaccharides. It has been speculated that the catalytic property of the enzymes is linked to the additional approximately 130 residues at the N terminus that are absent in other typical alpha-amylases. The crystal structure of a maltogenic amylase from a Thermus strain was determined at 2.8 A. The structure, an analytical centrifugation, and a size exclusion column chromatography proved that the enzyme is a dimer in solution. The N-terminal segment of the enzyme folds into a distinct domain and comprises the enzyme active site together with the central (alpha/beta)(8) barrel of the adjacent subunit. The active site is a narrow and deep cleft suitable for binding cyclodextrins, which are the preferred substrates to other starch materials. At the bottom of the active site cleft, an extra space, absent in the other typical alpha-amylases, is present whose size is comparable with that of a disaccharide. The space is most likely to host an acceptor molecule for the transglycosylation and to allow binding of a branched oligosaccharide for hydrolysis of alpha-D-(1,4)-glycosidic or alpha-D-(1,6)-glycosidic bond. The (alpha/beta)(8) barrel of the enzyme is the preserved scaffold in all the known amylases. The structure represents a novel example of how an enzyme acquires a different substrate profile and a catalytic versatility from a common active site and represents a framework for explaining the catalytic activities of transglycosylation and hydrolysis of alpha-D-(1,6)-glycosidic bond.

Amino Acid Sequence↗
PubMed1999

Accelerated emigration of B lymphocytes in the Xid mouse.

The B cell receptor is required for the emigration of newly generated B lymphocytes and for their maintenance in the periphery. A specific maintenance defect was noted in fraction I (IgDhighIgMlow) B cells in Xid mice (which harbor a mutation in Btk). Although Bcl-2 levels in fractions I and II (IgDhighIgMhigh) are equivalent in normal and Xid B cells, a novel peak of Bcl-2low fraction III (IgDlowIgMhigh) B cells was noted in the Xid mouse. Since this B cell population resembled bone marrow immature B cells, we examined the emigration of newly formed B cells in normal and Xid mice. These studies revealed the accelerated emigration of newly formed Xid B cells. We conclude that distinct Btk-independent and Btk-dependent signals mediate emigration and maintenance events during peripheral B cell maturation.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1999

Clinical evaluation of follow-up methods and results of atypical glandular cells of undetermined significance (AGUS) detected on cervicovaginal Pap smears.

OBJECTIVES: The aim of this study was to evaluate the efficacy of the follow-up methods and results of atypical glandular cells of undetermined significance (AGUS) detected on cervicovaginal Pap smears. METHODS: From May 1991 to December 1996, we have performed 407, 451 cervicovaginal Pap smears, of which 326 patients were identified as AGUS. Of the 326 patients, 268 patients were followed by repeat Pap smears, colposcopy, cone biopsy, or endometrial curettage. RESULTS: The incidence of AGUS on Pap smears is approximately 0.08%. The mean age of the patients was 43 years (range 22-79 years). The most common complaint was abnormal vaginal bleeding. The gross findings of the cervix were normal to mild erosion. The following past histories of patients could affect the AGUS results on Pap smear: 30 had cone biopsy, 21 had Pap smears on pregnancy and within 8 weeks after delivery or evacuation, 3 were on hormonal replacement therapy, 2 had intrauterine devices for contraception, and 5 were undergoing follow-up after treatment of cervical cancer. The benign lesions detected during follow-up periods were 6 microglandular hyperplasia of the cervix, 5 atypical squamous metaplasia of the cervix, 2 cervical endometriosis, 2 tubal metaplasia, 10 cervical myoma, 11 cervical polyps, 9 endometrial polyps, 3 uterine myoma, 1 pelvic endometriosis, 1 ovarian endometriosis, and 4 uterine adenomyosis. The premalignant or malignant lesions of the cervix were 4 low-grade squamous intraepithelial lesions, 24 high-grade squamous intraepithelial lesions, 8 glandular atypia/dysplasia, 5 adenocarcinoma in situ, 3 microinvasive adenocarcinoma, and 4 invasive adenocarcinoma. The neoplastic lesions of the uterus were 6 endometrial hyperplasia, 11 endometrial adenocarcinoma, 1 malignant mixed Müllerian tumor, and 1 metastatic endometrial adenocarcinoma. Sixty-seven (25%) of 268 patients followed up were identified as having clinically significant lesions of the cervix or uterus. The detection rates of abnormal lesions were 3.1% with repeated Pap smears (3/98), 28.4% with colposcopic-directed biopsy (31/109), 63.6% with cone biopsy (35/55), and 29.7% with endometrial curettage (19/64). CONCLUSION: AGUS on Pap smears showed various benign and malignant lesions of the cervix or uterus. The clinicians must communicate with the pathologists regarding the patient's clinical information as well as the origin of the atypical glandular cells in Pap smears. We recommend that patients with AGUS on Pap smear should undergo immediate intensive diagnostic studies, including colposcopic-directed biopsy with endocervical curettage or cone biopsy, to detect cervical lesions and endometrial curettage to detect endometrial lesions.

Adult↗
PubMed1999

Solid-phase microextraction for the determination of pethidine and methadone in human urine using gas chromatography with nitrogen-phosphorus detection.

A simple and rapid analytical method is presented for the determination of pethidine (meperidine) and methadone in human urine using solid-phase microextraction (SPME) and gas chromatography with nitrogen-phosphorus detection (GC-NPD). After the analytes had been partitioned between an extracting phase and the aqueous sample matrix, the needle of the coating fiber assembly was injected directly into the GC injector. The analytes were thermally desorbed in the heated injector (240 degrees C) and subsequently separated and detected by the GC-NPD system. The factors influencing the SPME method, such as the salt (NaCl) effect (15%), pH (pH 11), and equilibration time (30 min), were optimized. The calibration graphs for urine samples showed a good linearity. The detection limit was below 1 ng ml-1 for both drugs.

Chromatography, Gas↗
PubMed1999

Major histocompatibility complex differentiation in Sacramento River chinook salmon.

The chinook salmon of the Sacramento River, California, have been reduced to a fraction of their former abundance because of human impact and use of the river system. Here we examine the genetic variation at a major histocompatibility complex class II exon in the four Sacramento chinook salmon runs. Examination of the alleles found in these and other chinook salmon revealed nucleotide patterns consistent with selection for amino acid replacement at the putative antigen-binding sites. We found a significant amount of variation in each of the runs, including the federally endangered winter run. All of the samples were in Hardy-Weinberg proportions. A significant amount of genetic differentiation between runs was revealed by several measures of differentiation. Winter run was the most genetically divergent, while the spring, late-fall, and fall runs were less differentiated.

Alleles↗
PubMed1999

Modes of action of acarbose hydrolysis and transglycosylation catalyzed by a thermostable maltogenic amylase, the gene for which was cloned from a Thermus strain.

A maltogenic amylase gene was cloned in Escherichia coli from a gram-negative thermophilic bacterium, Thermus strain IM6501. The gene encoded an enzyme (ThMA) with a molecular mass of 68 kDa which was expressed by the expression vector p6xHis119. The optimal temperature of ThMA was 60 degrees C, which was higher than those of other maltogenic amylases reported so far. Thermal inactivation kinetic analysis of ThMA indicated that it was stabilized in the presence of 10 mM EDTA. ThMA harbored both hydrolysis and transglycosylation activities. It hydrolyzed beta-cyclodextrin and starch mainly to maltose and pullulan to panose. ThMA not only hydrolyzed acarbose, an amylase inhibitor, to glucose and pseudotrisaccharide (PTS) but also transferred PTS to 17 sugar acceptors, including glucose, fructose, maltose, cellobiose, etc. Structural analysis of acarbose transfer products by using methylation, thin-layer chromatography, high-performance ion chromatography, and nuclear magnetic resonance indicated that PTS was transferred primarily to the C-6 of the acceptors and at lower degrees to the C-3 and/or C-4. The transglycosylation of sugar to methyl-alpha-D-glucopyranoside by forming an alpha-(1,3)-glycosidic linkage was demonstrated for the first time by using acarbose and ThMA. Kinetic analysis of the acarbose transfer products showed that the C-4 transfer product formed most rapidly but readily hydrolyzed, while the C-6 transfer product was stable and accumulated in the reaction mixture as the main product.

Acarbose↗
PubMed1999

Cerebral blood flow during treatment for pulmonary hypertension.

AIM: To determine if the haemodynamics of systemic and cerebral circulation are changed during treatment for persistent pulmonary hypertension of the newborn (PPHN). METHODS: Fifteen term newborn piglets with hypoxia induced pulmonary hypertension were randomly assigned either tolazoline infusion (Tz), hyperventilation alkalosis(HAT), and inhaled nitric oxide (iNO). Mean pulmonary arterial pressure (PAP), mean systemic arterial pressure (SAP), and cerebral blood flow volume (CBF) were measured. RESULTS: During hypoxic breathing, PAP increased significantly in all groups. After treatment PAP decreased significantly in all groups, but no significant difference was observed between groups. SAP decreased significantly only in the Tz group, and CBF reduced significantly only in the HAT group. On the other hand, iNO did not change SAP or CBF. CONCLUSION: Inhaled NO might be ideal for the resolution of pulmonary hypertension.

Alkalosis, Respiratory↗
PubMed1999

Postnatal change of renal artery blood flow velocity and its relationship with urine volume in very low birth weight infants during the first month of life.

Although the renal artery blood flow velocity has been investigated recently using the ultrasound Doppler method, little is known about the longitudinal change of renal artery blood flow velocity and its relationship with urine volume in very low birth weight infant. Thus, we measured renal artery blood flow velocities by means of the pulse Doppler method in 28 very low birth weight infants. Maximum, minimum, and mean blood flow velocities were determined at postnatal days 0, 1, 2, 3, 4, 5, 6, 13, 20, and 27. The resistance index was also calculated. The maximum and mean blood flow velocities increased gradually after birth, and were significantly higher at 13, 20, and 27 days after birth. The minimum blood flow velocity and the resistance index were relatively constant during the study period. The mean blood flow velocities were also analyzed for any correlation with urine volume. There was a poor correlation between urine volume (ml/kg/day) and mean blood flow velocity (cm/s) (Y = 2.38X + 57.4, Y: urine volume, X: mean blood flow velocity, n = 161, r = 0.338, P < 0.01). However, if the mean renal artery blood flow velocity was less than 10 cm/s, oliguria was observed in most cases. The measurement of the renal artery blood flow velocities appears to be useful in understanding the background condition of renal function in very low birth weight infants.

Aging↗
PubMed1999

High CD99 expression in memory T and B cells in reactive lymph nodes.

We investigated the expression of CD99 in 35 hyperplastic perigastric lymph nodes, which were resected for gastric carcinoma or chronic peptic ulcer. Essentially, all lymphocytes in lymph nodes expressed CD99, but there were two populations with respect to the intensity of CD99 expression--CD99high and CD99low cells. We showed CD99high cells were distributed in paracortical and medullary cords by immunohistochemical study while germinal center cells were CD99low. Using three-color flow cytometric analysis with CD3, CD4, CD8, CD19, CD23, CD45RA, CD45RO, CD69, CD138, IgM, IgD, and IgG, most of CD99high cells were shown to be activated/memory T cells. CD4+CD45RO+ T cells were the subset revealing the highest intensity of CD99 expression while CD4+CD45RA+ T cells were CD99low. Among B cells, IgG+ B cells revealed a higher level of CD99 molecules than IgM+ B cells. These results suggest that CD99 is one of activation-related molecules which are upregulated in recently activated lymphocytes.

12E7 Antigen↗
PubMed1998

Generation of cells with Hodgkin's and Reed-Sternberg phenotype through downregulation of CD99 (Mic2).

Despite the fact that Hodgkin's and Reed-Sternberg (H-RS) cells are morphological hallmarks of Hodgkin's disease (HD), the nature of H-RS cells still remains to be resolved. Here we report that downregulation of CD99 (Mic2) leads to the generation of cells with an H-RS phenotype. IM9 and BJAB B-cell lines that were transfected with an antisense CD99 expression construct showed the morphological and immunological characteristics of H-RS cells such as multinuclearity, expression of CD15, decreased expression of major histocompatibility complex (MHC) class I and CD45RB, and deregulated secretion of cytokines. The reduced expression of CD99 was also confirmed in H-RS cells of patient's lymph nodes and three HD-derived cell lines, L428, KM-H2, and HDLM-2. Moreover, features characteristic of H-RS cells were completely abolished by forced expression of CD99 and by a constitutively active form of Rac, which functions downstream of CD99. We suggest that CD99 molecules play a crucial role in regulating functions and morphology of cells through a Rac-Rho signaling pathway and that the loss of CD99 expression is a significant molecular event to generate H-RS cells.

12E7 Antigen↗
PubMed1998

Determination of amphetamine, methamphetamine and dimethamphetamine in human urine by solid-phase microextraction (SPME)-gas chromatography/mass spectrometry.

A simple and rapid assay method for three stimulant drugs (amphetamine, methamphetamine, and dimethamphetamine) in human urine using solid-phase microextraction was developed. In solid-phase microextraction, the drugs were equilibrated between the adsorbent coated-fiber and aqueous sample matrix. After adsorption of the analytes, the fiber was directly transferred to the injector of a gas chromatograph, where the analytes were thermally desorbed and subsequently separated by the gas chromatograph and detected by mass spectrometer. The solid-phase microextraction method, which did not require solvents, was found to be a fast and simple analytical method. We optimized the solid-phase microextraction technique, for factors such as the NaCl salt effect (30%), pH effect (pH=12.4), equilibration time (30 min), desorption time (1 min) and coated-fiber type (100 microm poly(dimethylsiloxane)) and detected the stimulants in human urine, obtained from human subjects. The detection limits of each drug were below 1-10 ng/ml. The developed method can be applied to the abused drug test.

Amphetamine↗
PubMed1998

Analysis of the gene encoding cyclomaltodextrinase from alkalophilic Bacillus sp. I-5 and characterization of enzymatic properties.

The gene encoding cyclomaltodextrinase (CDase) was cloned from alkalophilic Bacillus sp. I-5. The nucleotide sequence of the gene was determined and the physicochemical properties of the enzyme were investigated. The gene had an open reading frame of 559 amino acids with a predicted molecular weight of 64,884. The enzyme was purified to near homogeneity from Escherichia coli cells carrying a recombinant plasmid that contained the CDase gene. The enzyme hydrolyzed cyclomaltoheptaose (beta-CD) 13 times better than starch and 33 times better than pullulan, and it had transglycosylation activity. The enzyme also hydrolyzed acarbose, a pseudotetrasaccharide inhibitor of glucosidases. The enzyme was stabilized by Ca2+ and the activity was increased more than twofold in the presence of 5 mM EDTA. The optimum temperature of the enzyme was elevated from 40 to 50 degrees C by Ca2+ ion and the thermal activity was maintained more than 80% at 60 degrees C in the presence of Ca2+. Comparison of known amino acid sequences of several amylolytic enzymes with cyclomaltodextrinase activity, site-directed mutagenesis of the enzyme, and substrate specificity of the enzyme imply that the region between the third and the fourth conserved regions of the enzyme may play an important role in binding and degradation of cyclomaltodextrin.

Acarbose↗
PubMed1998

Changes in the expression of c-myc, RB and tyrosine-phosphorylated proteins during proliferation of NIH 3T3 cells induced by hyaluronic acid.

We have shown that hyaluronic acid stimulates the proliferation of quiescent NIH 3T3 cells. We have shown that treatment of 1 mg/ml hyaluronic acid results in increase of tyrosine phosphorylation of two proteins, MW 124 kDa and 60 kDa as detected by anti-tyrosine antibodies by Western blot analysis. Maximum phosphorylation occurred within 2 h after addition of 1 mg/ml hyaluronic acid. Stimulation of proliferation was also accompanied by increase in c-Myc protein, which was inhibited by amlloride, an inhibitor of Na+/H+ antiporter and EGTA and increase in the steady state level of pRb, the RB gene product. These results suggest that the intracellular signal transduction pathways that mediate the stimulatory effects of hyaluronic acid on cellular proliferation are similar to those of growth factors.

3T3 Cells↗