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B Min

Publications and source records attributed to B Min.

At least 37 records · Page 2Linked to original sources
PubMed1999

Sophoricoside analogs as the IL-5 inhibitors from Sophora japonica.

Fruits of Sophora japonica L. (Leguminosae) exhibited an inhibitory effect in the IL-5 bioassay of mIL-5-dependent Y16 proliferation. The isoflavonoids of sophoricoside, genistein, orobol, and genistin were isolated as the IL-5 inhibitors from fresh fruits of the plant by activity-guided fractionation. Among the IL-5 inhibitors, sophoricoside exhibited the highest inhibitory effect with 89% inhibition at 12.5 microM, 82% at 6.3 microM, 72% at 3.1 microM, 59% at 1.6 microM, and 24% at 0.8 microM where the 50% inhibition (IC50) was shown at the concentration of 1.5 microM. Oxyphenylbutazone as the positive control exhibited the IC50 value at the concentration of 31.7 microM. In the order of IC50 values the inhibitory potency in the IL-5 bioassay was sophoricoside > orobol (9.8 microM) approximately equal to genistin (10.6 microM) > genistein (51.9 microM). The position of O-glycosylation and number of hydroxy groups in the isoflavonoids seem to play an important role in the inhibitory effect in the IL-5 bioassay.

Animals↗
PubMed1999

Archaeal aminoacyl-tRNA synthesis: diversity replaces dogma.

Accurate aminoacyl-tRNA synthesis is essential for faithful translation of the genetic code and consequently has been intensively studied for over three decades. Until recently, the study of aminoacyl-tRNA synthesis in archaea had received little attention. However, as in so many areas of molecular biology, the advent of archaeal genome sequencing has now drawn researchers to this field. Investigations with archaea have already led to the discovery of novel pathways and enzymes for the synthesis of numerous aminoacyl-tRNAs. The most surprising of these findings has been a transamidation pathway for the synthesis of asparaginyl-tRNA and a novel lysyl-tRNA synthetase. In addition, seryl- and phenylalanyl-tRNA synthetases that are only marginally related to known examples outside the archaea have been characterized, and the mechanism of cysteinyl-tRNA formation in Methanococcus jannaschii and Methanobacterium thermoautotrophicum is still unknown. These results have revealed completely unexpected levels of complexity and diversity, questioning the notion that aminoacyl-tRNA synthesis is one of the most conserved functions in gene expression. It has now become clear that the distribution of the various mechanisms of aminoacyl-tRNA synthesis in extant organisms has been determined by numerous gene transfer events, indicating that, while the process of protein biosynthesis is orthologous, its constituents are not.

Amino Acyl-tRNA Synthetases↗
PubMed1999

[Leukocyte glucocorticoid receptor and its mRNA levels in leukemia patients].

OBJECTIVE: To explore factors for differentiating non-Hodgkin's lymphoma cell leukemia (NHLCL) and acute lymphoblastic leukemia (ALL). METHODS: Leukocyte glucocorticoid receptor (GR) and GR mRNA levels were measured in 22 NHLCL, 18 ALL, 10 chronic lymphocytic leukemia (CLL) patients and 6 healthy subjects by using radio-ligand binding assay and molecular hybridization using GR cDNA as the probe. RESULTS AND CONCLUSIONS: The leukocyte GR and GR mRNA levels were significantly different between NHLCL and ALL(P < 0.01), and could be used as parameters for differential diagnosis of these two types of leukemia.

Adult↗
PubMed1998

Neonatal exposure to a self-peptide-immunoglobulin chimera circumvents the use of adjuvant and confers resistance to autoimmune disease by a novel mechanism involving interleukin 4 lymph node deviation and interferon gamma-mediated splenic anergy.

Induction of neonatal T cell tolerance to soluble antigens requires the use of incomplete Freund's adjuvant (IFA). The side effects that could be associated with IFA and the ill-defined mechanism underlying neonatal tolerance are setbacks for this otherwise attractive strategy for prevention of T cell-mediated autoimmune diseases. Presumably, IFA contributes a slow antigen release and induction of cytokines influential in T cell differentiation. Immunoglobulins (Igs) have long half-lives and could induce cytokine secretion by binding to Fc receptors on target cells. Our hypothesis was that peptide delivery by Igs may circumvent the use of IFA and induce neonatal tolerance that could confer resistance to autoimmunity. To address this issue we used the proteolipid protein (PLP) sequence 139-151 (hereafter referred to as PLP1), which is encephalitogenic and induces experimental autoimmune encephalomyelitis (EAE) in SJL/J mice. PLP1 was expressed on an Ig, and the resulting Ig-PLP1 chimera when injected in saline into newborn mice confers resistance to EAE induction later in life. Mice injected with Ig-PLP1 at birth and challenged as adults with PLP1 developed T cell proliferation in the lymph node but not in the spleen, whereas control mice injected with Ig-W, the parental Ig not including PLP1, developed T cell responses in both lymphoid organs. The lymph node T cells from Ig-PLP1 recipient mice were deviated and produced interleukin (IL)-4 instead of IL-2, whereas the spleen cells, although nonproliferative, produced IL-2 but not interferon (IFN)-gamma. Exogenous IFN-gamma, as well as IL-12, restored splenic proliferation in an antigen specific manner. IL-12-rescued T cells continued to secrete IL-2 and regained the ability to produce IFN-gamma. In vivo, administration of anti-IL-4 antibody or IL-12 restored disease severity. Therefore, adjuvant-free induced neonatal tolerance prevents autoimmunity by an organ-specific regulation of T cells that involves both immune deviation and a new form of cytokine- dependent T cell anergy.

Adjuvants, Immunologic↗
PubMed1998

Glutamyl-tRNA(Gln) amidotransferase in Deinococcus radiodurans may be confined to asparagine biosynthesis.

Asparaginyl-tRNA (Asn-tRNA) and glutaminyl-tRNA (Gln-tRNA) are essential components of protein synthesis. They can be formed by direct acylation by asparaginyl-tRNA synthetase (AsnRS) or glutaminyl-tRNA synthetase (GlnRS). The alternative route involves transamidation of incorrectly charged tRNA. Examination of the preliminary genomic sequence of the radiation-resistant bacterium Deinococcus radiodurans suggests the presence of both direct and indirect routes of Asn-tRNA and Gln-tRNA formation. Biochemical experiments demonstrate the presence of AsnRS and GlnRS, as well as glutamyl-tRNA synthetase (GluRS), a discriminating and a nondiscriminating aspartyl-tRNA synthetase (AspRS). Moreover, both Gln-tRNA and Asn-tRNA transamidation activities are present. Surprisingly, they are catalyzed by a single enzyme encoded by three ORFs orthologous to Bacillus subtilis gatCAB. However, the transamidation route to Gln-tRNA formation is idled by the inability of the discriminating D. radiodurans GluRS to produce the required mischarged Glu-tRNAGln substrate. The presence of apparently redundant complete routes to Asn-tRNA formation, combined with the absence from the D. radiodurans genome of genes encoding tRNA-independent asparagine synthetase and the lack of this enzyme in D. radiodurans extracts, suggests that the gatCAB genes may be responsible for biosynthesis of asparagine in this asparagine prototroph.

Acylation↗
PubMed1998

TCR agonist and antagonist exert in vivo cross-regulation when presented on Igs.

Ig-PLP1 and Ig-PLP-LR are chimeric Igs expressing proteolipid protein (PLP)-derived T cell agonist (PLP1) and antagonist (PLP-LR) peptides, respectively. Both chimeras, like free PLP1 and PLP-LR peptides, induce in vivo-specific T cell responses. However, the responses induced by Ig-PLP1 and Ig-PLP-LR were cross-reactive with both PLP1 and PLP-LR peptides, while those induced by free peptides were not. Surprisingly, despite the cross-reactivity of the responses, when Ig-PLP1 and Ig-PLP-LR were administered together into mice, a dose-dependent down-regulation of both T cell responses and a reduction of IL-2 production to background levels was observed. In contrast, when T cells induced by either Ig chimera were stimulated in vitro with mixtures of free PLP1 and PLP-LR peptides, there was no down-regulation of proliferation or decrease in IL-2 production. These data indicate that Ig-PLP1 and Ig-PLP-LR exert adverse reactions on one another at the level of naive T cells, resulting in an opposite antagonism. However, naive T cells experiencing either chimera develop into cross-reactive cells, acquire resistance to TCR triggering by closely related but different peptides, and support responsiveness.

Animals↗
PubMed1997

Presentation of a T cell receptor antagonist peptide by immunoglobulins ablates activation of T cells by a synthetic peptide or proteins requiring endocytic processing.

T cell receptor (TCR) antagonism is being considered for inactivation of aggressive T cells and reversal of T cell-mediated autoimmune diseases. TCR antagonist peptides silence aggressive T cells and reverse experimental allergic encephalomyelitis induced with free peptides. However, it is not clear whether free antagonist peptides could reverse natural disease where the antigen is presumably available for endocytic processing and peptides gain access to newly synthesized class II MHC molecules. Using an efficient endocytic presentation system, we demonstrate that a proteolipid protein (PLP) TCR antagonist peptide (PLP-LR) presented on an Ig molecule (Ig-PLP-LR) abrogates the activation of T cells stimulated with free encephalitogenic PLP peptide (PLP1), native PLP, or an Ig containing PLP1 peptide (Ig-PLP1). Free PLP-LR abolishes T cell activation when the stimulator is free PLP1 peptide, but has no measurable effect when the stimulator is the native PLP or Ig-PLP1. In vivo, Ig-PLP1 induces a T cell response to PLP1 peptide. However, when coadministered with Ig-PLP-LR, the response to PLP1 peptide is markedly reduced whereas the response to PLP-LR is normal. Free PLP-LR coadministered with Ig-PLP1 has no effect on the T cell response to PLP1. These findings indicate that endocytic presentation of an antagonist peptide by Ig outcompete both external and endocytic agonist peptides whereas free antagonist hinders external but not endocytic agonist peptide. Direct contact with antagonist ligand and/or trans-regulation by PLP-LR-specific T cells may be the operative mechanism for Ig-PLP-LR-mediated downregulation of PLP1-specific T cells in vivo. Efficient endocytic presentation of antagonist peptides, which is the fundamental event for either mechanism, may be critical for reversal of spontaneous T cell-mediated autoimmune diseases where incessant endocytic antigen processing could be responsible for T cell aggressivity.

Animals↗
PubMed1997

[IL-2, IFN-gamma, and TNF-alpha mRNA expression in peripheral blood mononuclear cells in patients with multiple sclerosis].

We determined the cytokine messenger RNA (mRNA) expression patterns of peripheral blood mononuclear cells from 17 patients with multiple sclerosis (MS) and 11 normal controls, by using a quantitative reverse transcription in combination with polymerase reaction (RT/PCR) and Southern blot hybridization method. A significantly higher levels of IL-2, IFN-gamma mRNA in patient with MS compared to normal controls and significantly higher level of expressions of IFN-gamma, TNF-alpha mRNA were detected in active MS patients compared to those with stable desease (P < 0.05). These data further support the central role of some cytokines in the pathophysiology of this autoimmune disease.

Adult↗
PubMed1997

[An approach to operative treatment for acute abdomen complicated by malignant hemopathy].

The experience of operative treatment in 14 cases of acute abdomen complicated by malignant hemopathy was reported. Primary diseases consisted of AL, NHL, MM, MH and MDS-RA, 13 cases of them were at progressing stage. The acute abdominal conditions included acute appendicitis, acute pancreatitis, acute cholecystitis, peritonitis secondary to intestinal perforation, intestinal obstruction, primary peritonitis and ileocecal syndrome. The type of acute abdomen was related with primary desease and chemotherapy. 8 cases were operated and 2 of them died of complications after operation. Biopsy of excised tissue showed tumor cells in 2 cases. The rate of correllation between preoper active and postoperative diagnosis was 62.5%. These findings suggest that malignant infiltration in the viscera, duration of abdominal pain before operation and the change of blood picture are the major factors for determining operative indication and the postoperative prognosis.

Abdomen, Acute↗
PubMed1996

The effect of probenecid on the pharmacokinetics of zalcitabine in HIV-positive patients.

PURPOSE: The purpose of this study was to determine the potential effect of probenecid on the pharmacokinetics of zalcitabine in HIV-positive patients. METHODS: Twelve patients received single oral 1.5 mg doses of zalcitabine alone and during probenecid treatment (500 mg at 8 and 2 hours before and 4 hours after zalcitabine dosing) in an open-label, randomized two-way crossover study with a one-week washout period between treatments. Serial blood and urine samples were collected over a 24 hour period and assayed for zalcitabine by a modified GC/MS method. RESULTS: Coadministration of probenecid with zalcitabine resulted in a decrease in mean (%CV) renal clearance of zalcitabine from 310 (28%) ml/min when zalcitabine was given alone to 180 (22%) ml/min with probenecid and a prolonged half-life from 1.7 hours to 2.5 hours. Mean AUCs increased from 59 ng.h/ml when zalcitabine was given alone to 91 ng.h/ml when given with probenecid. Considering the short half-life of zalcitabine (1-3 hours) relative to its dosing schedule, the pharmacokinetic changes observed in this study are not expected to result in significant accumulation during chronic dosing. CONCLUSIONS: The results of this study show that co-administration of probenecid with zalcitabine results in a moderate decrease in renal clearance of zalcitabine due to inhibition of renal tubular secretion and a 50% increase in drug exposure. Although well tolerated in this single-dose study, patients taking this combination should be monitored closely for signs of toxicity and dosage reduction should be considered if warranted.

Administration, Oral↗
PubMed1995

The influence of orlistat on the pharmacokinetics and pharmacodynamics of glyburide in healthy volunteers.

To assess the influence of orlistat on the pharmacokinetics and pharmacodynamics (the blood glucose-lowering effect) of glyburide, an open-label, placebo-controlled, randomized, two-way crossover study was done in 12 healthy male volunteers. Each subject received single 5-mg oral doses of glyburide (Micronase; The Upjohn Company, Kalamazoo, MI) on the fifth day of treatment with placebo (treatment A) and 80-mg orlistat (treatment B) three times a day for 4 1/3 days; the two treatments were separated by a five-day washout period. Serial blood samples were collected before and at appropriate intervals after each glyburide dose to determine plasma concentrations and blood glucose levels. Values of Cmax and AUC of glyburide showed an equality of the two treatments by the analysis of variance. There was an apparent correlation between blood glucose level and the logarithm of plasma glyburide concentration; this relationship appeared to not be altered when glyburide was administered with orlistat. In conclusion, orlistat administered at doses of 80-mg three times daily does not significantly alter the pharmacokinetics and blood glucose-lowering effect of a single 5-mg oral dose of glyburide in healthy volunteers.

Adult↗
PubMed1995

Surface characteristics and properties of lumbrokinase-immobilized polyurethane.

Potent and novel fibrinolytic enzymes (lumbrokinase [LK]) were extracted from the earthworm, Lumbricus rubellus. These enzymes were very stable and showed greater antithrombotic activity than other currently used fibrinolytic proteins. An LK fraction showing the most potent fibrinolytic activity was immobilized onto a polyurethane (PU) surface to investigate its enzymatic activity and antithrombotic activity. A methanol-extracted PU surface was coated with 3% (wt/vol) maleic anhydride methylvinyl ether copolymer (MAMEC)/tetrahydrofuran (THF) solution, and the surface was incubated in an LK solution/phosphate-buffered saline (PBS, pH 7.4). The surface properties were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA), and dynamic contact angle. The stability of immobilized LK was determined by caseinolytic activity assay and the specificity of immobilized LK on fibrinogen/fibrin was observed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The antithrombotic activity of immobilized LK was evaluated using an ex vivo rabbit A-A shunt experiment. LK immobilization was confirmed by ATR-FTIR and ESCA. Immobilized LK demonstrated stable proteolytic activity during various incubation periods. Immobilized LK proteolyzed fibrinogen and fibrin almost specifically, while it hardly hydrolyzed other plasma proteins including plasminogen and albumin. In the ex vivo A-A shunt experiment, the LK-immobilized surface significantly prolonged occlusion time over control surfaces. This is primarily due to the high thrombolytic activity of immobilized LK. In this work, a highly efficient surface modification method on the PU surface was developed, and this LK immobilization technique will be very useful in improving the blood compatibility of blood-contacting devices.

Animals↗
PubMed1995

Characterization of a Chlamydomonas reinhardtii gene encoding a protein of the DNA photolyase/blue light photoreceptor family.

The organization and nucleotide sequence of a gene from Chlamydomonas reinhardtii encoding a member of the DNA photolyase/blue light photoreceptor protein family is reported. A region of over 7 kb encompassing the gene was sequenced. Northern analysis detected a single 4.2 kb mRNA. The gene consists of eight exons and seven introns, and encodes a predicted protein of 867 amino acids. The first 500 amino acids exhibit significant homology with previously sequenced DNA photolyases, showing the closest relationship to mustard (Sinapis alba) photolyase (43% identity). An even higher identity, 49%, is obtained when the Chlamydomonas gene product is compared to the putative blue-light photoreceptor (HY4) from Arabidopsis thaliana. Both the Chlamydomonas and the Arabidopsis proteins differ from the well characterized DNA photolyases in that they contain a carboxyl terminal extension of 367 and 181 amino acids, respectively. However, there is very little homology between the carboxyl terminal domains of the two proteins. A previously isolated Chlamydomonas mutant, phr1, which is deficient in DNA photolyase activity, especially in the nucleus, was shown by RFLP analysis not to be linked to the gene we have isolated. We propose this gene encodes a candidate Chlamydomonas blue light photoreceptor.

Amino Acid Sequence↗
PubMed1995

The effect of food on pharmacokinetics of zalcitabine in HIV-positive patients.

PURPOSE: The purpose of this study was to determine the effect of food on the pharmacokinetics of zalcitabine in HIV-positive patients. METHODS: Twenty patients received single oral 1.5 mg doses of zalcitabine with and without a standard breakfast in an open-label, randomized crossover study with at least a one week washout period between treatments. Serial blood and urine samples were collected over 24 hours and assayed for zalcitabine by a modified GC/MS method. RESULTS: Administration with food delayed and prolonged absorption resulting in a decrease of approximately 39% in maximal plasma concentrations compared to dosing under fasting conditions. Comparison of plasma AUC values indicated a small (14%) reduction in bioavailability when given with food. Approximately 59% and 45% of the dose were excreted unchanged in the urine under fasting and fed conditions, respectively. CONCLUSIONS: The results of this study show that the administration of zalcitabine with food results in a mild reduction in bioavailability. Although these changes are not expected to be of clinical importance, further studies must be conducted for confirmation.

AIDS-Related Complex↗
PubMed1995

PDGF and TGF-beta mediate collagen production by mesangial cells exposed to advanced glycosylation end products.

Deposition of type III collagen protein is increased when cultured rat mesangial cells are cultured in media containing high glucose concentrations. Possible mechanisms for this effect include the production of growth factors, such as PDGF and TGF-beta, and the formation of abnormal glucose-protein adducts called advanced glycosylation end products (AGEs). In our studies, neutralizing antibodies to PDGF and TGF-beta prevented increased type III collagen deposition by mesangial cells exposed either to high glucose media or to low glucose media containing AGEs. Daily addition of PDGF or TGF-beta stimulated type III collagen production. However, while co-incubation with the TGF-beta Ab prevented PDGF-stimulated type III collagen production, the PDGF Ab did not prevent TGF-beta-stimulated type III collagen production. Daily addition of PDGF or TGF-beta stimulated, while AGEs inhibited, mesangial cell proliferation after 96 hours. We propose that high extracellular glucose and AGEs stimulate type III collagen production by pathways that involve the intermediate formation of PDGF and TGF-beta by mesangial cells. PDGF may increase type III collagen production by stimulating the intermediate production of TGF-beta. Exposure to high glucose, AGEs, or TGF-beta also leads to impaired mesangial cell proliferation. The autocrine effects of TGF-beta and PDGF play important roles in the effects of high extracellular glucose and AGEs on cultured mesangial cells.

Analysis of Variance↗
PubMed1995

[Risk factors for Guillain-Barre syndrome in northern China: a case-control study].

We conducted a case-control study in northern China to estimate possible risk factors for Guillain-Barre Syndrome (GBS). Forty patients were consecutively seen at the PUMC hospital and the Second Hospital of Hebei Medical College between July and September 1991. The diagnosis was established following the NINCDS criteria for GBS. Among 36 patients with measurements of motor evoked potentials, 34 had evidences of demyelination. Eighty controls chosen from spouses or siblings, and neighbors or work/school mates, were matched by sex and age (+/- 3 years). Using the Mantel-Haenszel estimate of the odds ratio, cold rain, overloaded activities, a history of diarrhea, common cold, and exposure to organophosphorus one month before onset, significantly increased, at least six-fold, the risk for development of GBS. Cases and controls did not differ in the number of previous vaccinations. We suggest that a single antigent is less likely of etiological importance in GBS.

Adolescent↗
PubMed1994

Antithrombogenicity of lumbrokinase-immobilized polyurethane.

Lumbrokinase is a potent fibrinolytic enzyme purified from the earthworm, Lumbricus rubellus. We immobilized 18 IU/cm2 of lumbrokinase to polyurethane using maleic anhydride methylvinyl ether copolymer (MAMEC) as an enzyme carrier, and the proteolytic and fibrinolytic activities of immobilized lumbrokinase were assayed. Immobilized lumbrokinase retained about 34% of its activity, compared with soluble lumbrokinase activity. Immobilized lumbrokinase showed stability against thermal inactivation and degradation and within a various pH range. The optimal pH of immobilized lumbrokinase shifted 1.0 pH unit upward compared with soluble enzyme. Upon exposure to the human whole blood, less amount of 125I-fibrinogen was adsorbed to lumbrokinase-immobilized surface than to the polyurethane control surface. The lumbrokinase-immobilized surface showed less platelet adhesion than did the MAMEC-grafted surface. At the early stage of platelet adhesion, the number of adhered platelets increased on the lumbrokinase-immobilized surface with increasing time; yet, the platelet number drastically decreased on the lumbrokinase-immobilized surface after 80 min incubation. This suggests that lumbrokinase-immobilized polyurethane digested the adsorbed fibrinogen and inhibited platelet adhesion on the surface, probably by inhibiting fibrinogen adsorption to be highly antithrombogenic. Clinical applications of this material to artificial organs should be developed in the near future.

Adsorption↗