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B Lu

Publications and source records attributed to B Lu.

At least 145 records · Page 8Linked to original sources
PubMed1998

Targeted disruption of the interferon-gamma receptor 2 gene results in severe immune defects in mice.

To study the role of the interferon- (IFN) gammaR2 chain in IFN-gamma signaling and immune function, IFN-gammaR2-deficient mice have been generated and characterized. Cells derived from IFN-gammaR2 -/- mice are unable to activate either JAK/STAT signaling proteins or gene transcription in response to IFN-gamma. The lack of IFN-gamma responsiveness alters IFN-gamma-induced Ig class switching by B cells from these mice. In vitro cultures of T cells demonstrate that the T cells from the IFN-gammaR2 -/- mice have a defect in Th1 cell differentiation. The IFN-gammaR2 (-/-) mice also produce lower amounts of IFN-gamma in response to antigenic challenge. In addition, IFN-gammaR2 -/- mice are defective in contact hypersensitivity and are highly susceptible to infection by Listeria monocytogenes. These results demonstrate that the IFN-gammaR2 is essential for IFN-gamma-mediated immune responses in vivo.

Animals↗
PubMed1998

Intersubunit interactions allowing a carboxylate mutant coat protein to inhibit tobamovirus disassembly.

Tobacco mosaic tobamovirus (TMV) coat protein (CP) mutant E50Q lacks a repulsive intersubunit carboxylate group and can effectively inhibit the disassembly of wild-type TMV (Culver et al, 1995, Virology 206,724). To investigate the ability of this mutant CP to block disassembly, a series of second-site amino acid substitutions were added to the E50Q CP. These second-site mutations were designed to disrupt specific intersubunit stabilizing interactions involving hydrophobic or polar residues, salt bridges, and CP-RNA contacts. Results showed substitutions disrupting intersubunit interactions that face the disassembling surface of the virion dramatically reduced the ability of CP E50Q to inhibit TMV disassembly. Substitutions that disrupted the CP inner loop, RNA binding capabilities, or intersubunit interactions that faced away from the disassembling surface did not dramatically interfere with CP E50Q's ability to inhibit disassembly. Taken together, these findings suggest that intersubunit interactions made by 5' terminal E50Q subunits, not associated with RNA, provide the stabilizing forces that prevent virion disassembly. The role of these stabilizing interactions in TMV disassembly and their potential use for creating disassembly inhibiting CPs are discussed.

Capsid↗
PubMed1998

Neurokinin-1 (NK-1) receptor is required in Clostridium difficile- induced enteritis.

Toxin A, a 308,000-Mr enterotoxin from Clostridium difficile, mediates antibiotic-associated diarrhea and colitis in humans. Injection of toxin A into animal intestine triggers an acute inflammatory response characterized by activation of sensory neurons and immune cells of the intestinal lamina propria, including mast cells and macrophages, and migration of circulating neutrophils in the involved intestinal segment. In this study we show that mice genetically deficient in the neurokinin-1 receptor are protected from the secretory and inflammatory changes as well as from epithelial cell damage induced by toxin A. The protective effect of neurokinin-1R deletion correlates with diminished intestinal levels of the cytokine TNF-alpha and its mRNA and the leukocyte enzyme myeloperoxidase. These results demonstrate a major requirement for substance P receptors in the pathogenesis of acute inflammatory diarrhea.

Animals↗
PubMed1998

Estrogen receptor-beta mRNA variants in human and murine tissues.

Estrogen receptor (ER)-beta mRNA splice variants have been identified in human breast tumors as well as normal human and mouse ovarian, uterine and mammary tissues. In both species transcripts deleted in exons 5 or 6, or 5 + 6 have been characterized by RT-PCR followed by cloning and sequencing. In mouse tissues an ER-beta transcript containing 54 nucleotides inserted in frame between exons 5 and 6 was identified. Interestingly, no equivalent of the mouse inserted transcript was detected in any of the four human tissues analyzed.

Amino Acid Sequence↗
PubMed1998

Molecular cloning and expression of ps20 growth inhibitor. A novel WAP-type "four-disulfide core" domain protein expressed in smooth muscle.

We previously reported the purification of ps20 (Rowley, D. R., Dang, T. D., Larsen, M., Gerdes, M. J., McBride, L., and Lu, B. (1995) J. Biol. Chem. 270, 22058-22065), a urogenital sinus mesenchymal cell secreted protein having growth-inhibitory properties. We report here cloning of the 1.03-kilobase rat ps20 cDNA clone from the PS-1 (adult rat prostate smooth muscle) cDNA library. Partial clones were obtained by nested polymerase chain reaction with degenerate primers, and full-length ps20 cDNA clones were isolated by plaque hybridization. Sequence analysis revealed that ps20 protein contains a WAP-type "four-disulfide core" motif and is a novel member of the WAP signature protein family composed primarily of secreted serine protease inhibitors. Native ps20 immunoprecipitated from smooth muscle cells and recombinant ps20 both resolved on SDS-polyacrylamide gel electrophoresis with apparent molecular mass of 27-29 kDa under reducing conditions and 21-23 kDa under non-reducing conditions, respectively. Stable ps20-transfectant COS-7 cell lines secreted ps20 and were growth-inhibited relative to mock transfectants. In addition, COS-7 and prostate carcinoma PC-3 cells were growth-inhibited by bacterially expressed ps20. Northern analysis indicated differential expression by tissue with highest expression in the heart. Immunohistochemical localization of ps20 protein showed cell-specific expression by both visceral and vascular smooth muscle in all tissues, including the prostate gland. These results indicate ps20 is a novel growth-regulatory member of the WAP signature family expressed by smooth muscle cells.

Amino Acid Sequence↗
PubMed1998

Abnormalities in monocyte recruitment and cytokine expression in monocyte chemoattractant protein 1-deficient mice.

Monocyte chemoattractant protein 1 (MCP-1) is a CC chemokine that attracts monocytes, memory T lymphocytes, and natural killer cells. Because other chemokines have similar target cell specificities and because CCR2, a cloned MCP-1 receptor, binds other ligands, it has been uncertain whether MCP-1 plays a unique role in recruiting mononuclear cells in vivo. To address this question, we disrupted SCYA2 (the gene encoding MCP-1) and tested MCP-1-deficient mice in models of inflammation. Despite normal numbers of circulating leukocytes and resident macrophages, MCP-1(-/-) mice were specifically unable to recruit monocytes 72 h after intraperitoneal thioglycollate administration. Similarly, accumulation of F4/80+ monocytes in delayed-type hypersensitivity lesions was impaired, although the swelling response was normal. Development of secondary pulmonary granulomata in response to Schistosoma mansoni eggs was blunted in MCP-1(-/-) mice, as was expression of IL-4, IL-5, and interferon gamma in splenocytes. In contrast, MCP-1(-/-) mice were indistinguishable from wild-type mice in their ability to clear Mycobacterium tuberculosis. Our data indicate that MCP-1 is uniquely essential for monocyte recruitment in several inflammatory models in vivo and influences expression of cytokines related to T helper responses.

Animals↗
PubMed1998

Response patterns with indirect UV detection in capillary zone electrophoresis.

Capillary zone electrophoresis with indirect UV-detection was used to separate mixtures containing both positively and negatively charged species. In order to understand the dependence of detector response patterns on the changes in compositions of the background electrolytes and the charge of marker ions (UV-absorbing ions), the separations were performed in two different systems. In a three-ion system (analyte ion, coion and counterion) a marker ion was the major ionic component of a buffer solution and in a two-coion or counterion system the marker ion was used as an additive. In the three-ion system the response profile of an analyte was in good agreement with the mathematical treatment based on the Kohlrausch regulation function. In the two-coion or counterion system the response patterns were more complicated; however, the experimental results agree well with data obtained from a computer simulation program. Peak directions of the analytes were not only determined by their relative charge to the marker ion, but were also associated with their relative mobilities to the buffer coion and the marker ion. The analytes with higher effective mobilities compared to the marker ion were detected as positive peaks and the ones with lower effective mobilities as negative peaks. Similarly to the three-ion system, the detector response of an analyte was stronger by applying a marker coion compared to a counterion. An interesting result was obtained in the separation of a mixture of quaternary ammonium ions and sugars by using a cationic marker ion. The highest and most symmetrical peak was not a cation, but raffinose anion, which appeared most closely to the system peak. The observation suggests that the electromigration dispersion in its zone was eliminated by migrating close to the electroosmosis. A system peak with the mobility corresponding to the electroosmotic flow was obtained in both systems, and an additional system peak with a mobility close to that the marker ion was present in the systems using marker ions as additives.

Electrophoresis, Capillary↗
PubMed1998

Stimulation of 125I-transferrin binding and 59Fe uptake in rat adipocytes by vanadate: treatment time determines apparent tissue sensitivity.

Vanadium compounds have been documented to stimulate a number of insulin biological effects in vitro and in vivo. We previously demonstrated stimulation of glucose transport and insulin-like growth factor-II (IGF-II) binding in rat adipocytes. These actions are associated with translocation of glucose transporters and IGF-II receptors from an intracellular compartment to the plasma membrane. The transferrin receptor is also recruited to the plasma membrane in response to insulin. Freshly isolated rat adipocytes were incubated with vanadate and insulin at 37 degrees C, and after treating the cells with KCN to inhibit further receptor movement, diferric 125I-transferrin binding was assayed. Vanadate stimulated a dose- and time-dependent increase in 125I-transferrin binding, reaching maximum (approximately threefold) stimulation at 1 mmol/L after a 4-hour incubation. This was equivalent to the maximum insulin effect that was obtained with 10(-8) mol/L after 30 minutes. A similar degree of stimulation was achieved with 0.1 mmol/L vanadate after 8 hours of exposure. Dose-response data showed that the apparent sensitivity to vanadate was time-dependent and increased with the duration of exposure (EC50: 30 minutes, 1 mmol/L; 3 hours, 0.35 mmol/L). Scatchard analysis of 125I-transferrin binding showed that both insulin and vanadate increased receptor binding capacity with no effect on receptor affinity. Total cellular transferrin receptor content measured by immunoblotting with monoclonal anti-transferrin receptor antibody (OX-26) was not altered by insulin or vanadate, consistent with receptor translocation. Assessment of 59Fe uptake from 59Fe-labeled diferric transferrin showed that vanadate augmented 59Fe uptake in a dose-dependent manner to an extent similar to insulin, demonstrating the functional activity of the receptors (percent of control: 10(-8) mol/L insulin, 175% +/- 23.8%, P < .02; 0.3 mmol/L vanadate, 188% +/- 17.3%, P < .01). We conclude that vanadate mimics insulin to augment cell surface transferrin receptors and increase Fe uptake in rat adipocytes. The time-dependent apparent increase in sensitivity is consistent with the effectiveness of very low concentrations of vanadate in vivo after several days of administration, and suggests a requirement for vanadate entry into cells to mediate this biological response.

Adipocytes↗
PubMed1998

Cloning and characterization of glial cell line-derived neurotrophic factor receptor-B: a novel receptor for members of glial cell line-derived neurotrophic factor family of neurotrophic factors.

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor with diverse biological functions. Signal transduction of GDNF is mediated by binding to a glycosyl-phosphatidylinositol (GPI)-linked receptor GDNFR-alpha and activation of c-RET tyrosine kinase. The recent discovery of a new GDNF homolog neurturin raises the possibility that multiple receptors exist for the members in the GDNF family. Here we report isolation of the gene encoding a new receptor called GDNFR-beta. Sequence analysis indicated that GDNFR-beta is also a GPI-linked protein, with 47% identity to GDNFR-alpha. The GDNFR-beta transcript was preferentially expressed in the brain, spleen and lung, but moderate levels of GDNFR-beta mRNA were also found in kidney and the entire gastrointestinal track. In situ hybridization revealed high expression levels in the entorhinal cortex and olfactory bulb, followed by cortex, septum, inferior and superior colliculus, and zona inserta. A laminar pattern of expression was detected in layer III of the cortex. Treatment with GDNF of PC12 cells transfected with the GDNFR-beta gene activated mitogen-activated protein kinase (MAPK) and elicited neurite outgrowth. GDNFR-alpha and GDNFR-beta together form a new family of GPI-linked receptors for GDNF-like molecules.

Amino Acid Sequence↗
PubMed1998

Asymmetric cell division: lessons from flies and worms.

Insights into the mechanisms of asymmetric cell division have recently been obtained from studies in genetically amenable systems such as Drosophila and Caenorhabditis elegans. These studies have emphasized the importance of cortically localized polarity organizing molecules, adapter molecules, and the actin cytoskeleton in controlling unequal segregation of cell-fate determinants and spindle orientation. The control of asymmetric cell divisions by Wnt signaling in C. elegans and Frizzled signaling in Drosophila reveals additional mechanisms for modulating cellular polarity and suggests that there are some similarities between the two systems.

Actin Cytoskeleton↗
PubMed1998

Electron-beam CT angiography with three-dimensional reconstruction in the evaluation of coronary artery bypass grafts.

RATIONALE AND OBJECTIVES: The authors evaluated the use of electron-beam computed tomographic (CT) angiography and three-dimensional (3D) reconstruction for evaluation of coronary artery bypass grafts (CABGs). MATERIALS AND METHODS: Sixty patients (53 men and seven women; mean age, 56 years +/- 8) with 152 CABGs (29 internal mammary artery and 123 saphenous vein grafts) underwent electron-beam CT with 3D reconstruction. The time from bypass surgery to CT scanning was 7 days to 120 months (mean, 17 months +/- 28). Enhanced single-section and flow mode studies were performed in all cases. The results were correlated with CABG operation records, and patency was determined with time-attenuation curves. RESULTS: All patients were successfully examined. On the basis of time-attenuation curve criteria, 124 (81.6%) of 152 grafts were patent. The patency rate for the internal mammary artery subgroup was 93% (27 of 29 grafts); for the saphenous vein graft subgroup, 78.9% (97 of 123 grafts). CONCLUSION: Used in contrast-enhanced, single-section mode and flow studies with time-attenuation curves, electron-beam CT angiography with 3D reconstruction can provide quantitative data for evaluation of CABG patency.

Adult↗
PubMed1998

Polyamine inhibition of estrogen receptor (ER) DNA-binding and ligand-binding functions.

Polyamines are known to inhibit sequence specific DNA-binding activity of several zinc-finger transcription factors, including estrogen receptor (ER) binding to its cognate estrogen response element (ERE). The mechanism accounting for this disruption of protein-DNA interaction is unknown, although polyamine induction of DNA conformational changes has been suggested. To determine if polyamines can directly impair ER action, we compared the effects of putrescine (Putr), spermidine (Spd), and spermine (Spm) on ER DNA-binding (ER-ERE complex formation), ER ligand-binding (estradiol), ER structure (circular dichroism and sucrose gradient sedimentation), and the capacity of ER to transactivate an ERE-tk-CAT reporter in transient transfection assays. Polyamine concentrations causing 50% inhibition of ER-ERE formation (IC50 values) were found to be 1 mM for Putr, 4 mM for Spd, and 3 mM for Spm. This loss of ER DNA-binding was associated with a direct and irreversible effect on the ER DNA-binding domain (ER-DBD). Additionally, polyamines were observed to inhibit ER ligand-binding with IC50 values of 10 mM for Putr, 2 mM for Spd, and < 0.1 mM for Spm; and this correlated with a measureable change in higher-order ER structure (5S to 3.5S sedimentation) and inhibition of intracellular ER transactivation. These findings suggest that in ER-positive human breast tumors with increased polyamine (especially Spm) content, ER structure and function may be directly altered by tight-ion polyamine complexing that results in loss of ER-mediated gene regulation.

Breast↗
PubMed1998

Expression of the tpr protease gene of Porphyromonas gingivalis is regulated by peptide nutrients.

The Tpr protease of Porphyromonas gingivalis W83 is a membrane-associated enzyme capable of hydrolyzing chromogenic substrates for trypsin and bacterial collagenases. A previous study by us indicated that Tpr expression was increased under conditions of nutrient limitation. In the present study, we further characterized expression of the tpr gene using a tpr::lacZ reporter gene construct under a range of nutrient conditions. In P. gingivalis, transcription of tpr was initiated 215 bp upstream of the coding region and regulation of tpr expression was at the level of transcription. Deletion mutations in the tpr upstream region identified the promoter region immediately upstream of the transcription start site, determined by primer extension analysis. Three identical 17-bp direct repeats identified within the 5' end of tpr mRNA were involved in tpr regulation. In an Escherichia coli background, tpr transcription was initiated after an AT-rich region upstream of tpr but not at the P. gingivalis start site. Tpr expression in P. gingivalis was suppressed by the addition of peptide and protein nutrients to a peptide-limited growth medium but was only slightly affected by addition of free amino acids. Low-molecular-weight fractions of brain heart infusion rich in phenylalanine, proline, and alanine had the greatest inhibitory effects on expression of the tpr::lacZ construct. Addition of the dipeptide phenylalanyl-phenylalanine to the growth medium resulted in a 10-fold decrease in tpr expression. This suggests that specific phenylalanine-containing peptides are a major factor controlling Tpr expression. Neither hemin starvation, heat shock, nor pH change had significant effects on Tpr expression.

Base Sequence↗
PubMed1998

Localization of transforming growth factor-beta1 and type II receptor in developing normal human prostate and carcinoma tissues.

Transforming growth factor-beta1 (TGF-beta1) is implicated in prostate development, and elevated expression of TGF-beta1 has been correlated with prostate carcinogenesis. In this study, cell type specificity of TGF-beta1 and TGF-beta receptor Type II (RcII) protein expression was determined by immunocytochemistry in human normal prostate and compared to prostate carcinoma tissues. Heterogeneous localization patterns of LAP-TGF-beta1 (TGF-beta1 precursor) and RcII were observed in both epithelial and mesenchymal cells in fetal prostate, with LAP-TGF-beta1 localizing to more basal epithelial cells. Homogeneity of LAP-TGF-beta1 staining was increased in neonatal, prepubertal, and adult prostate, with elevated immunoreactivity noted in epithelial acini relative to stromal tissue for both LAP-TGF-beta1 and RcII proteins. In stromal tissues, RcII cell localization exhibited staining patterns nearly identical to smooth muscle alpha-actin. In prostate carcinoma, LAP-TGF-beta1 localized to carcinoma cells with an increased staining heterogeneity relative to normal prostate. In contrast to normal epithelial cells, carcinoma epithelial cells exhibited low to nondetectable RcII staining. Stromal cell staining patterns for LAP-TGF-beta1 and RcII in carcinoma, however, were identical to those of normal prostate stromal cells. These studies implicate both epithelial and stromal cells as sites of TGF-beta1 synthesis and RcII localization in the developing and adult normal human prostate. In addition, these data indicate a loss of epithelial expression of RcII concurrent with altered LAP-TGF-beta1 expression in human prostate carcinoma cells.

Adolescent↗
PubMed1998

[Causative ananlysis for redislocation after operative reduction of congenital dislocation of hip].

Redislocation of the femoral head may be occured after its operative reduction in the congenital dislocation of the hip, therefore, it is greatly important to disclose the causes of the redislocation in order to avoid this every complication and improve the curative effect of this operation. Seven cases of redislocation from 106 cases (128 sides) of the congenital dislocation of the hip which had been reduced operatively were studied with relative measurements of the hip joints on roentgenogram, associated their pathologic conditions described in operation. The results showed that, in these cases, there were (0.843 +/- 0.692) cm upward displacement of the femoral head beyond the horizontal Y line, (68.86 +/- 0.692) degree of the femoral anteversion, the more lateral displacement of the femoral head compared to the opposite side and the acetabular index increasing up to (33.86 +/- 3.72) degree from (26.14 +/- 2.73) degree of the operative correction. These phenomena indicate that the redislocation after operative reduction of the femoral head in congenital dislocation of the hip is mainly related to four causes which include the existence of large pressure between acetabulum and femoral head, the uncorrected abnormal femoral anteversion, the residue of the pathologic tissues in the acetabulum and the reascending of the acetabular index having been corrected in operation.

Child↗
PubMed1998

[The application of low tidal volume pressure-controlled ventilation in patients with acute respiratory distress syndrome].

Low tidal volume pressure-controlled ventilation therapy was used in 32 patients with ARDS. There were resulted a lower peak inspiratory pressure (PIP) level than that of control group, thus a decline in incidence of overventilation and the overventilation induced mortality. The results suggest that low tidal volume pressure-controlled ventilation may consider as preferred ventilation mortality in management of ARDS.

Adolescent↗
PubMed1998

[Comparative study of tetracycline-estrone and estrone effects on bone histomorphometric parameters in ovariectomized rats].

OBJECTIVE: To compare the effects of tetracycline-estrone (TE) and estrone (E) on bone histomorphometric parameters of femoral distal diaphysis in ovariectomized (OVX) rats. METHODS: Twenty female rats were randomly allocated into four groups, 5 rats in each: tetracycline-estrone (TE), estrone (E), OVX and sham operation (S). The OVX rats were used as a model for osteoporosis. After being fed with TE or E for 13 weeks, all rats were sacrificed. The effects of TE and E on bone microarchitecture and dynamics were studied by bone histomorphometry. RESULTS: The histomorphometric data showed that the connectivity of trabecular bone in TE and E groups was significantly improved in comparision with that in S group (P < 0.05). The dynamic data indicated that in TE and E group, the tetracycline labelled and osteoid surfaces were remarkably increased in comparision with those in OVX group, especially the data in TE group were significantly higher than those in E group and other two groups (P < 0.05). CONCLUSIONS: The connectivity of trabecular bone could be significantly improved by both TE and E. The activation frequency seemed to be higher in TE group than that in E group.

Animals↗