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Biomedical subjects

C Song

Publications and source records attributed to C Song.

At least 37 records · Page 2Linked to original sources
PubMed2001

Biodistribution and dosimetry of pretargeted monoclonal antibody 2D12.5 and Y-Janus-DOTA in BALB/c mice with KHJJ mouse adenocarcinoma.

UNLABELLED: Biodistribution and dosimetry of 88Y (and equimolar 90Y) Janus-dodecanetetraacetic acid (DOTA) were performed using a three-step pretargeting protocol in BALB/c mice bearing mouse mammary adenocarcinoma (KHJJ) implants. Pretargeting was performed with mouse monoclonal antibody (mAb) 2D12.5 specific for yttrium-DOTA, and the chase was Y-DOTA-human transferrin conjugate. In this article, we report extensive organ dosimetry and the theoretic limits of the radionuclide physical half-life (T(p)) for pretargeting. METHODS: Organ biodistribution data were obtained from bioassays on tissue taken from tumor mice killed at 3, 24, 48, 72, 96, and 120 h after intravenous injection of 88Y-Janus-DOTA. Uptake and retention of 88Y as a function of time were described by nonlinear least squares fits of the tissue data to multiexponential functions. Radiation dose estimates for equivalent molar amounts of 90Y were subsequently derived from these time-integrated functions. RESULTS: The results were as follows: rapid blood clearance of 88Y-Janus-DOTA; rapid uptake and slow clearance of 88Y-Janus-DOTA from the tumor over 5 d; rapid clearance from all organs and body; largest radiation absorbed dose (AD) per injected dose of 63.52 (cGy/MBq) to tumor; high therapeutic ratios (AD tumor/AD tissue), particularly for blood and bone; and optimal radionuclide T(p) range from 30 min to 10 d. CONCLUSION: Although the absolute concentration of 90Y in the tumor is less using the hapten system than is achieved generally with the chelated radionuclide covalently attached to the mAb, the achievable tumor uptake of radioactivity, coupled with low radioactivity in bone, blood, and other organs, suggests that a three-step pretargeting protocol has considerable promise as a method for 90Y radioimmunotherapy.

Adenocarcinoma↗
PubMed2001

[Analysis of the association between HLA-DRB(1), DQB(1) gene and pulmonary tuberculosis complicated with diabetes mellitus].

OBJECTIVE: To analyze the association between HLA DRB(1), DQB(1) allele and pulmonary tuberculosis complicated with type 2 diabetes mellitus among Han nationality of northern Chinese. METHODS: By using PCR-SSP technique, the genomic DNA typing was applied to compare the difference of the gene frequency between patients and normal controls. The relative risks (RR) of the disease were also estimated. 214 cases were observed, including 123 pulmonary tuberculosis complicated with type 2 diabetes mellitus, 45 type 2 diabetes mellitus, and 46 normal subjects. All these cases were respectively hospitalized in Beijing Thoracic Tumor & Tuberculosis Hospital, Tianjin Lung Disease Hospital, Beijing Thoracic Disease Hospital, Shijiazhuang Diabetes Hospital, from 1998 to 1999. RESULTS: The frequency of DRB(1) * 09 allele in pulmonary tuberculosis complicated with type 2 diabetes mellitus cases was significantly higher than that of DRB(1) * 09 allele in normal controls, 25.10% Vs 14.03%, RR = 2.22, the frequency of DRB(1) * 09 allele in cases was also significantly higher than that of DRB(1) * 09 allele in type 2 diabetes mellitus controls, 25.1% Vs 9.32%, RR = 3.16; the frequency of DQB(1) * 05 allele was significantly lower than that of DQB(1) * 05 allele in normal controls and diabetes mellitus, 7.17% Vs 19.24%, RR = 0.30, 7.17% Vs 21.12%, RR = 0.26. CONCLUSIONS: The results indicate that the DRB(1) * 09 allele is susceptive to the pulmonary tuberculosis complicated with type 2 diabetes mellitus, the DQB(1) * 05 may be protective to the pulmonary tuberculosis complicated with diabetes mellitus. The DRB(1) * 09 allele and DQB(1) * 05 allele may affect the incidence of the pulmonary tuberculosis complicated with type 2 diabetes mellitus, or real effect genes link with them.

Adult↗
PubMed2001

[Association of HLA-DRB1 genes with pulmonary tuberculosis].

OBJECTIVE: To assess the association of HLA-DRB1 genes with pulmonary tuberculosis (PTB) and the correlation between HLA-DRB1 alleles and clinical manifestations of patients with PTB. METHOD: Alleles at the HLA-DRB1 typing were analyzed by polymerase chain reaction with sequence-specific primers (PCR-SSP) in 74 patients and 90 healthy controls. RESULTS: Compared with controls, a significant increased frequency of DRB1 * 15 was found (34.3% vs 17.0%, Pc < 0.05, RR = 2.91). The frequency of DRB1 * 12 was also increased, but the difference was not statistically significant(15.4% vs 7.5%, Pc > 0.05). The frequency of DRB1 * 11 was significantly decreased (1.4% vs 9.9%, Pc < 0.05, RR = 0.12). More retreated and drug-resistant cases were found in DRB1 * 15 positive patients than in DRB1 * 15 negative patients. CONCLUSIONS: These results show that HLA-DRB1 * 15 allele is susceptible gene in PTB, DRB1 * 11 may be a protective allele, HLA-DRB1 * 15 allele may be related to patients with refractory PTB.

Adolescent↗
PubMed2000

Ca2+- and phosphatidylinositol 3-kinase-dependent nitric oxide generation in lung endothelial cells in situ with ischemia.

Endothelial cells generate nitric oxide (NO) in response to agonist stimulation or increased shear stress. In this study, we evaluated the effects of abrupt cessation of shear stress on pulmonary endothelial NO generation and its relationship to changes in intracellular Ca(2+). In situ endothelial generation of NO and changes in intracellular Ca(2+) in isolated, intact rat lungs were evaluated using fluorescence microscopy with diaminofluorescein diacetate, an NO probe, and Fluo-3, a Ca(2+) probe. The onset of increased NO generation in endothelial cells of subpleural microvessels in situ occurred between 30 and 90 s after onset of ischemia and was preceded by an increase in intracellular Ca(2+) due to both influx of extracellular Ca(2+) and release from intracellular stores. Flow cessation-induced NO generation in endothelial cells in situ was Ca(2+)-, calmodulin-, and PI3-kinase-dependent. The similarity of endothelial cell response (increased NO generation) to either increased flow or cessation of flow suggests that cells respond to an imposed alteration from a state of adaptation. This response to flow cessation may constitute a compensatory vasodilatatory mechanism and may play a role in signaling for cell proliferation and vascular remodeling.

Animals↗
PubMed2000

Regulation of a novel human phospholipase C, PLCepsilon, through membrane targeting by Ras.

Phosphoinositide-specific phospholipase C (PI-PLC) plays a pivotal role in regulation of intracellular signal transduction from various receptor molecules. More than 10 members of human PI-PLC isoforms have been identified and classified into three classes beta, gamma, and delta, which are regulated by distinct mechanisms. Here we report identification of a novel class of human PI-PLC, named PLCepsilon, which is characterized by the presence of a Ras-associating domain at its C terminus and a CDC25-like domain at its N terminus. The Ras-associating domain of PLCepsilon specifically binds to the GTP-bound forms of Ha-Ras and Rap1A. The dissociation constant for Ha-Ras is estimated to be approximately 40 nm, comparable with those of other Ras effectors. Co-expression of an activated Ha-Ras mutant with PLCepsilon induces its translocation from the cytosol to the plasma membrane. Upon stimulation with epidermal growth factor, similar translocation of ectopically expressed PLCepsilon is observed, which is inhibited by co-expression of dominant-negative Ha-Ras. Furthermore, using a liposome-based reconstitution assay, it is shown that the phosphatidylinositol 4,5-bisphosphate-hydrolyzing activity of PLCepsilon is stimulated in vitro by Ha-Ras in a GTP-dependent manner. These results indicate that Ras directly regulates phosphoinositide breakdown through membrane targeting of PLCepsilon.

Amino Acid Sequence↗
PubMed2000

Yb14ZnSb11: charge balance in zintl compounds as a route to intermediate Yb valence

The results of thermodynamic, transport, and x-ray diffraction measurements of single crystals of the new compound Yb14ZnSb11 are presented. These data indicate an intermediate Yb valence scenario, with a spin fluctuation temperature of approximately 85 K. The compound is weakly metallic and is isostructural with the charge-balanced Zintl compound Yb14AlSb11. The intermediate Yb valence can be qualitatively accounted for by considering the charge counting arguments of the nonmetallic parent, and charge balance in Zintl-related materials appears to be a viable route to designing other compounds with intermediate valence constituents.

Journal Article↗
PubMed2000

Morphing the shell model into an effective theory

We describe a strategy for attacking the canonical nuclear structure problem-bound-state properties of a system of point nucleons interacting via a two-body potential-which involves an expansion in the number of particles scattering at high momenta, but is otherwise exact. The required self-consistent solutions of the Bloch-Horowitz equation for effective interactions and operators are obtained by an efficient Green's function method based on the Lanczos algorithm. We carry out this program for the simplest nuclei, d and 3He, in order to explore the consequences of reformulating the shell model as a controlled effective theory.

Journal Article↗
PubMed2000

Role of Raf-1 conserved region 2 in regulation of Ras-dependent Raf-1 activation.

Full activation of Raf-1 requires the interaction of its CRD with Ras. The serine/threonine-rich region, CR2, of Raf-1 was implicated in Raf-1 regulation, but the underlying mechanism was unclear. Here we show that CRD loses its Ras-binding activity when expressed in connection with CR2, suggesting that CR2 masks CRD. This masking effect is abolished by substitution of Asp or Ala for Ser-259, a growth factor- and TPA-induced phosphorylation site in CR2. Treatment of COS-7 cells expressing Ha-Ras(Val-12) and Raf-1 with TPA enhances the Ha-Ras(Val-12)-dependent Raf-1 kinase activity. In contrast, the Ha-Ras(Val-12)-dependent activities of the Raf-1(S259D) and Raf-1(S259A) mutants are comparable to that of wild-type Raf-1 stimulated by both Ha-Ras(Val-12) and TPA and cannot be further stimulated by TPA treatment. These results suggest that the in vivo phosphorylation of Ser-259 may comprise a crucial step for Ras-dependent Raf-1 activation by unmasking CRD and promoting its association with Ras.

Animals↗
PubMed2000

Immunosuppressive effects of clozapine and haloperidol: enhanced production of the interleukin-1 receptor antagonist.

In schizophrenic patients, multiple immune abnormalities have been reported, including increased production of proinflammatory cytokines. There is some evidence that antipsychotic drugs may have immunosuppressive effects. The aim of this study was to examine the in-vitro effects of different concentrations of antipsychotic agents on cytokine production by human whole blood. We examined the effects of clozapine and haloperidol, 10(-4), 10(-6) and 10(-8)M, on the unstimulated and stimulated (lipopolysaccharide+phytohemagglutinin) production of interleukin-6 (IL-6), IL-10, interferon-gamma (IFNgamma), and the IL-1 receptor antagonist (IL-1RA). Clozapine, 10(-6) and 10(-8)M, and haloperidol, 10(-4), 10(-6), and 10(-8)M, significantly increased the unstimulated and stimulated production of IL-1RA. Clozapine 10(-6)M significantly increased the stimulated production of IFNgamma. Clozapine 10(-4)M significantly suppressed the unstimulated production of IL-6 and IL-1RA and the stimulated production of IL-6, IL-10, IFNgamma and IL-1RA. The results suggest that both clozapine and haloperidol, at concentrations within the therapeutic range, may exert immunosuppressive effects through an enhanced production of IL-1RA.

Adult↗
PubMed2000

A transcriptional defect underlies B lymphocyte dysfunction in a patient diagnosed with non-X-linked hyper-IgM syndrome.

To establish the underlying cause of hyper-IgM syndrome in one female patient, B cell function was examined in response to CD40- and IL-4-mediated pathways. When CD40-induced functional responses were measured in unfractionated B cells, CD80 up-regulation, de novo Cmu-Cgamma recombination, and Igamma transcription were all found to be relatively unaffected. However, CD40- and IL-4-mediated CD23 up-regulation and VDJ-Cgamma transcription were clearly diminished compared to control cells. IL-4-induced CD23 expression was measurably reduced in the CD20- population as well. These results suggested that the patient's defect is positioned downstream of CD40 contact and affects both CD40- and IL-4 signal transduction pathways. Further analysis of B cell function in CD19+ B cells revealed a clear B cell defect with respect to Igamma and mature VDJ-Cgamma transcription and IgG expression. However, under the same conditions Iepsilon transcription was relatively normal. Partial restoration of B cell function occurred if PBMC or CD19+ B cells were cultured in vitro in the presence of CD154 plus IL-4. Because addition of IL-4 to cocultures containing activated T cells failed to induce B cells to undergo differentiation, the ability of the patient's B cells to acquire a responsive phenotype correlated with receiving a sustained signal through CD40. These findings support a model in which the patient expresses an intrinsic defect that is manifested in the failure of specific genes to become transcriptionally active in response to either CD154 or IL-4 and results in a functionally unresponsive B cell phenotype.

B-Lymphocytes↗
PubMed2000

Superoxide possibly produced in endothelial cells mediates the neutrophil-induced lung injury.

BACKGROUND: The mechanism by which stimulated neutrophils (polymorphonuclear leukocytes [PMNs]) damage pulmonary vascular endothelium was investigated. METHODS: The ability of unstimulated and mechanically stimulated PMNs to adhere to pulmonary endothelial cells and, thereby, alter pulmonary vascular permeability was tested. Each series was conducted on 6 rats. To stimulate PMNs, they were agitated gently in a glass vial for 10 seconds. RESULTS: Perfusing lungs with the stimulated PMNs elicited a fivefold increase in permeability compared with lungs perfused with the unstimulated cells. This increase in permeability was blocked completely by preincubation of stimulated PMNs with CD18 monoclonal antibody. This increase in permeability was also blocked completely by superoxide dismutase (SOD) or the xanthine oxidase (XO) inhibitor allopurinol. Pulmonary vascular hemodynamics were unaffected by any treatment protocol. The accumulation of stimulated PMNs within the lungs was not inhibited by SOD but was partially blocked by allopurinol. CONCLUSIONS: These findings suggest that stimulated PMN-induced increases in pulmonary vascular filtration resulted from endothelial cell injury caused by superoxide anion possibly generated by XO, exclusively present in the endothelial cells.

Animals↗
PubMed2000

Selective activation of liver X receptor alpha by 6alpha-hydroxy bile acids and analogs.

We have found that certain natural 6alpha-hydroxylated bile acids are receptor-specific activators of nuclear liver X receptor alpha (LXRalpha) (NR1H3), a nuclear receptor regulating the expression of the cholesterol 7alpha-hydroxylase gene, coding for the rate-limiting enzyme in the major pathway of bile acid synthesis. The LXR homolog, ubiquitous nuclear receptor (UR/LXRbeta) (NR1H2), was also activated by these bile acids, but at higher concentrations than for LXRalpha. Synthetic 6alpha-hydroxylated bile acid analogs were synthesized with LXRalpha-selective agonistic activity, with potential to modulate cholesterol catabolism in hypercholesterolemia.

Bile Acids and Salts↗
PubMed2000

The in vitro immunosuppressive effects of moclobemide in healthy volunteers.

BACKGROUND: Many studies have demonstrated that major depression is related to an activation of the inflammatory response system (IRS) with an increased production of proinflammatory cytokines. It has been shown that tricyclic antidepressants and serotonin reuptake inhibitors suppress the activation of the IRS in depression and have negative immunoregulatory effects in vitro. Little is known on the immune effects of moclobemide, a reversible monoamine oxidase A inhibitor. METHODS: We examined, in nine normal volunteers, the in vitro effects of moclobemide on the production of interleukin-6 (IL-6), IL-8, tumor necrosis factor-alpha (TNFalpha), interferon-gamma (IFNgamma), IL-10 and the IL-1 receptor antagonist (IL-1RA) by diluted whole blood stimulated or not with lipopolysaccharide (LPS)+phytohemagglutinin (PHA). RESULTS: Moclobemide 10(-3) and 10(-5) M significantly suppressed the unstimulated production of TNFalpha and IL-8, and significantly enhanced the stimulated-production of IL-10. The production of IL-6, IL-1RA and IFNgamma was not significantly affected either in the unstimulated or stimulated conditions. CONCLUSIONS: Moclobemide has negative immunoregulatory capacities through inhibition of the production of proinflammatory cytokines, i.e. TNFalpha and IL-8, and through enhancement of the production of IL-10, an anti-inflammatory cytokine.

Adult↗
PubMed2000

Endothelial signal transduction system enhances neutrophil-induced pulmonary vascular permeability.

The mechanism by which stimulated polymorphonuclear leukocytes and neutrophils (PMNs) damage pulmonary vascular endothelium was investigated. The authors assessed the ability of unstimulated and mechanically stimulated PMNs to adhere to pulmonary endothelial cells and, thereby, alter pulmonary vascular permeability, measured as the pulmonary filtration coefficient (K) and haemodynamics. PMNs were stimulated by gentle agitation in a glass vial for 10 s. Perfusing lungs with the stimulated PMNs (n=6) resulted in significant accumulation of PMNs within the lungs, assessed by myeloperoxidase levels, and elicited a 4-fold increase in K and a 2-fold increase in pulmonary vascular resistance as compared to lungs perfused with unstimulated cells (n=6). The increases in K were completely blocked by GF109203X, a protein kinase C inhibitor (n=6); however, GF109203X only partially attenuated the increase in vascular resistance and had little effect on the accumulation of stimulated PMNs. An agonist of protein kinase C, phorbol myristate acetate, elicited dose dependent increases in both K and pulmonary vascular resistance even in the absence of PMNs (n=6). These findings indicate that the increases in pulmonary filtration coefficient and pulmonary vascular resistance induced by polymorphonuclear neutrophils result from endothelial cell injury mediated by activation of protein kinase C within the endothelial cells themselves.

Animals↗
PubMed2000

A polymorphic CD40 ligand (CD154) molecule mediates CD40-dependent signalling but interferes with the ability of soluble CD40 to functionally block CD154:CD40 interactions.

We report the characterization of a naturally occurring polymorphism in CD40 ligand (CD40L, CD154) expressed by activated T cells from a young female patient. This polymorphism encodes a nonconservative Gly --> Arg substitution in amino acid 219 in the extracellular, CD40 binding domain of the molecule. Studies carried out with 293 epithelial cells ectopically expressing the polymorphic protein (CD154/G219R) revealed reduced levels of binding to different anti-CD154 monoclonal antibodies (mAb) and CD40-immunoglobulin (CD40-Ig). However, recognition of the polymorphic and wild-type CD154 molecules by a polyclonal antiserum was comparable, suggesting that the polymorphism affects the ability of the protein to interact with CD40 but does not significantly alter its surface expression. To determine if reduced cross-linking of CD40 mediated decreased functional effects, three CD40-dependent properties were measured. We found that pathways leading to the induction of surface CD23, CD80, and Igamma transcription were activated in response to CD154/G219R signalling. However, the decrease in affinity for CD40 by the mutated CD154 affected the ability of CD40-Ig to efficiently interfere with the binding and effectively block induced CD80 expression. In contrast, we found that the 5c8 mAb, which recognized the polymorphic molecule to a similar extent as wild-type CD154, effectively blocked the interaction between CD154/G219R and CD40 as measured by CD80 expression. These findings suggest that naturally occurring polymorphisms in the CD154 molecule may affect the ability of CD40-mediated functions to be blocked by soluble CD40 or anti-CD154 mAb in the therapeutic treatment of disease and graft rejection.

B7-1 Antigen↗
PubMed2000

Difference in the effects of low temperatures on the tension of human pulmonary artery and vein ring segments.

BACKGROUND: Although limited data suggest that pulmonary flushing with organ preservation solutions should not be performed at too low temperatures, the influence of temperature on pulmonary vascular tone is unclear. OBJECTIVE: The purpose of this study was to examine the effect of low temperatures of the tension of human pulmonary artery and vein ring segments and the vascular resistance of perfused rat lungs. METHODS: 5 sets of human pulmonary artery and vein ring segments were suspended from a force displacement transducer at 37, 24 and 8 degrees C, and the effect of 30 mM K(+) on the tension was monitored. The effect of 30 mM K(+) on vascular resistance was also examined at low temperatures in 5 perfused rat lungs. RESULTS: Pulmonary artery segments dilated at 24 degrees C, and more significant vasodilatation was observed at 8 degrees C. In contrast, there was a significant constriction of pulmonary veins at 8 degrees C. Vasoconstriction induced by 30 mM K(+) at 37 degrees C was significantly inhibited at low temperatures in both pulmonary arteries and veins. In rat lungs, perfusion at 8 degrees C caused a significant increase in pulmonary vascular resistance, even though no further increase was observed in the presence of 30 mM K(+). CONCLUSIONS: Our data indicate that pulmonary arteries dilate and the veins constrict at 8 degrees C and may increase pulmonary vascular resistance. We conclude that the different effect of low temperatures between pulmonary arteries and veins may explain why pulmonary vascular flushing with organ preservation solutions at room temperature is more satisfactory.

Adult↗
PubMed2000

Cholestenoic acid is a naturally occurring ligand for liver X receptor alpha.

Excessive cholesterol is eliminated from extrahepatic cells by reverse cholesterol transport, a process by which neutral sterols are transferred to extracellular acceptor lipoproteins for further transport to the liver. Another process independent of lipoproteins involves excretion of 3beta-hydroxy-5-cholesten-25(R)-26-carboxylic (cholestenoic) acid, a metabolite of 27-hydroxycholesterol. Physiological concentrations of cholestenoic acid activated the nuclear receptor liver X receptor alpha (LXR alpha; NR1H3), but not other oxysterol receptors. As a ligand, cholestenoic acid modulated interaction of LXR alpha with the nuclear receptor coactivator Grip-1. Cholestenoic acid, therefore, may function as a signaling molecule for regulation of lipid metabolism via LXR alpha.

Cell Line↗