Biomedical subjects

G Liu

Publications and source records attributed to G Liu.

At least 181 records · Page 10Linked to original sources

PubMed2001

[The risk of sustained amenorrhea in patients with systemic lupus erythematosus receiving intermittent pulse cyclophosphamide therapy].

OBJECTIVE: To determine the risk of sustained amenorrhea in premenopausal women with systemic lupus erythematosus (SLE) receiving intermittent pulse cyclophosphamide (CTX) therapy. METHODS: Prospectively comparing the amenorrhea rate of 51 cases receiving intermittent pulse cyclophosphamide therapy versus that of 22 cases receiving intermittent pulse methylprednisolone (MP) therapy. RESULTS: The amenorrhea rate was higher in the CTX group (19.6%) than in the MP group (P = 0.025). In the CTX group, the amenorrhea rate of patients aged over 30 was higher than that of patients aged 30 or below 30 (P = 0.0018). CONCLUSION: Pulse CTX therapy in fertile women with SLE is associated with increased rate of sustained amenorrhea, and the older the patient is, the higher risk for sustained amenorrhea the patient runs.

Adult↗

PubMed2001

[Study on bolus cyclosphamide treatment for 64 cases of lupus nephritis].

OBJECTIVE: To report on the dosing, efficacy and side-effects of bolus cyclosphamide treatment for lupus nephritis (LN). METHODS: 64 consecutive cases of LN with 10 or more erythrocytes per high-power field, proteinuria (> 1 g of protein per day) and serum creatinine increased (> 133 mumol/L) were treated by bolus therapy with cyclophosphamide (CTX) given monthly for 6 months and then quarterly for 18 months. RESULTS: 49 patients had renal remission (defined as < 10 erythrocytes per high-power field, absence of cellular casts, excretion of < 1 g of protein per day and normal serum creatinine). The mean of doses was 1.1 g for each time (0.6-1.6 g), the mean of times of bolus CTX needed was 3.6 (1-8 times). The adverse events were amenorrhea (in 41% female patients), herpes zoster (in 13% patients) and hemorrhagic cystitis (in 1 patient). CONCLUSION: The results indicate that monthly bolus CTX therapy is effective and safe for patients with LN. Its adverse effect is relatively not a serious problem.

Amenorrhea↗

PubMed2001

[The experimental study of intratemporal facial nerve regeneration in chitin chamber].

OBJECTIVE: To investigate the feasibility of intratemporal facial nerve regeneration in a chitin chamber. METHODS: A left 6 mm intratemporal facial nerve gap was created in adult white rabbit, and a total of 48 animals were used. The proximal and distal stumps were bridged with chitin chamber (experimental group) and silicone chamber (control group). Regeneration of the nerve was assessed by gross observation, nerve electrophysiological test, histological examination and digital morphological analysis in both groups. RESULTS: 1. Three months after implantation, the proximal transected neural stump was connected with the distal stump in the chitin chamber. Five months after operation, the regenerated nerve exhibited a more nature fascicular organization and the chitin tubes were completely absorbed. 2. Nerve evoked potentials showed better conduction ability in the chitin chamber. There were no significant difference in electrophysiological indices between the two chamber groups. 3. Most of the regenerated nerve fibers were myelinated nerve fibers, and axons and myelins had similar histograms between the experimental and control groups. 4. Five months after operation, the mean percentage of recovery of the regenerated nerve fiber area, axonal area and axonal number were more than 71% in the experimental group. There was no significant difference between the control and experimental groups. CONCLUSION: These results suggested that intratemporal facial nerve could regenerate effectively within the chitin chamber in rabbits and such kind of chamber may be clinically useful.

Animals↗

PubMed2001

[The fluorescent properites of the complexes of 1,3-diphenyl-4-acyl-5-pyrazolones with Eu(III)].

The binary and ternary Eu(III) complexes have been prepared with four 1,3-diphenyl-4-acyl-5-pyazolones as ligands (where the four acyls are benzoyl, phenylacetyl, butyryl and choroacetyl, and the compounds are represented by DPBZP, DPPAP, DPBTP, DPCAP respectively). The composition of the complexes was determined by chemical and elementary analysis, and the structure of the complexes was characterized by FTIR spectra. The fluorescence spectra of the complexes were measured. It is indicated that the complexes emit with the characteristic fluorescence of Eu(III), the fluorescence intensity of the complexes are closely related to the substituents at the acyl at 4-position in pyrazolone ring of the ligands, depending on the ligands, the descending order of the fluorescence intensity is DPBZP > DPPAP > DPBTP > DPCAP, and that the second ligand, 1, 10-phenanthroline, remarkably intensifies the fluorescence of the complexes.

English Abstract↗

PubMed2001

[Establishment and characterization of human inflammatory breast carcinoma neoplasm transplantation in nude mice].

OBJECTIVE: To establish and characterize human inflammatory breast cancer xenograft in nude mice. METHODS: Animal studies, Northern and Western blot, zymograms and immunohistochemistry were used in our studies. RESULTS: Human transplantable inflammatory carcinoma were established in nude mice. This xenograft as its human counterpart exhibited striking erythema of the overlying skin, lympho-vascular invasion and other similar biological characteristics. It also exhibited lung metastasis 4-6 weeks after growth. This xenograft was ER, PR, Her-2/neu negative and p53, EGFR positive. Comparative studies of inflammatory breast cancer xenograft with non-inflammatory xenograft indicated 10-20 fold overexpression of E-cadherin and MUC1. CONCLUSIONS: This human inflammatory breast carcinoma xenograft will provide an excellent animal model to allow us to further dissect out both the upstream regulatory machinery and downstream effector molecules responsible for the inflammatory carcinoma phenotype.

Animals↗

PubMed2000

Roles of Se and NO in apoptosis of hepatoma cells.

Mice inoculated with hepatoma cell (H22) suspension subcutaneously at their right axilla were administered orally with kappa-selenocarrageenan (Se) solution, the inoculated hepatoma's growth was suppressed. Different concentrations of Se solution added in human hepatoma cell line culture could inhibit proliferation and induce apoptosis in hepatoma cells. Meanwhile Se solution could increase the activity of glutathione peroxidase (GSH-Px) in the mice's plasma and the content of NO in the mice's sera and the hepatoma cell culture supernatant as well. Therefore, apoptosis in hepatoma cell induced by Se solution may be associated with the increase in antioxidative activity, the suppression free radical's intervention, and the excessive release of NO by stress.

Animals↗

PubMed2000

Graphite microparticles as coatings for quartz crystal microbalance-based gas sensors.

The use of graphite particles (1-2 microm) as coatings on quartz crystal microbalances (QCMs) for detection and monitoring of toluene and other volatile organic compounds (VOCs) is described. Unlike the more commonly used polymeric coatings with low glass transition temperatures (Tg), particulate graphitic coatings are not as susceptible to loss of acoustic energy when coating thickness or operational temperature increases. This situation enables the use of relatively thick coatings, which increases the absolute amount of vapor sorbed in the coating and, consequently, lowers the level of detection and enhances operation over a wide temperature range. The use of small size particles also results in a coating with a more porous structure, which facilitates uptake and release of VOCs in comparison to coatings made from high Tg polymers, which have a lower porosity. These attributes, coupled with the inherent stability of graphitic materials, make particulate graphite coatings especially suitable for applications at high temperatures. The advantages of using particulate graphite as a coating on QCMs are demonstrated by comparison to the performance of a few low-Tg polymers [i.e., poly(isobutylene) and poly(diphenoxyphosphazene)] and high-Tg polymers (i.e., polystyrene).

Crystallization↗

PubMed2000

Enhanced multispecificity of arabidopsis vacuolar multidrug resistance-associated protein-type ATP-binding cassette transporter, AtMRP2.

Recent investigations have established that Arabidopsis thaliana contains a family of genes encoding ATP-binding cassette transporters belonging to the multidrug resistance-associated protein (MRP) family. So named because of the phenotypes conferred by their animal prototypes, many MRPs are MgATP-energized pumps active in the transport of glutathione (GS) conjugates and other bulky amphipathic anions across membranes. Here we show that Arabidopsis MRP2 (AtMRP2) localizes to the vacuolar membrane fraction from seedlings and is not only competent in the transport of GS conjugates but also glucuronate conjugates after heterologous expression in yeast. Based on the stimulatory action of the model GS conjugate 2,4-dinitrophenyl-GS (DNP-GS) on uptake of the model glucuronide 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG) and vice versa, double-label experiments demonstrating that the two substrates are subject to simultaneous transport by AtMRP2 and preloading experiments suggesting that the effects seen result from cis, not trans, interactions, it is inferred that some GS conjugates and some glucuronides reciprocally activate each other's transport via distinct but coupled binding sites. The results of parallel experiments on AtMRP1 and representative yeast and mammalian MRPs indicate that these properties are specific to AtMRP2. The effects exerted by DNP-GS on AtMRP2 are not, however, common to all GS conjugates and not simulated by oxidized glutathione or reduced glutathione. Decyl-GS, metolachlor-GS, and oxidized glutathione, although competitive with DNP-GS, do not promote E(2)17betaG uptake by AtMRP2. Reduced glutathione, although subject to transport by AtMRP2 and able to markedly promote E(2)17betaG uptake, neither competes with DNP-GS for uptake nor is subject to E(2)17betaG-promoted uptake. A multisite model comprising three or four semi-autonomous transport pathways plus distinct but tightly coupled binding sites is invoked for AtMRP2.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2000

A family of peptidoglycan recognition proteins in the fruit fly Drosophila melanogaster.

Peptidoglycans from bacterial cell walls trigger immune responses in insects and mammals. A peptidoglycan recognition protein, PGRP, has been cloned from moths as well as vertebrates and has been shown to participate in peptidoglycan-mediated activation of prophenoloxidase in the silk moth. Here we report that Drosophila expresses 12 PGRP genes, distributed in 8 chromosomal loci on the 3 major chromosomes. By analyzing cDNA clones and genomic databases, we grouped them into two classes: PGRP-SA, SB1, SB2, SC1A, SC1B, SC2, and SD, with short transcripts and short 5'-untranslated regions; and PGRP-LA, LB, LC, LD, and LE, with long transcripts and long 5'-untranslated regions. The predicted structures indicate that the first group encodes extracellular proteins and the second group, intracellular and membrane-spanning proteins. Most PGRP genes are expressed in all postembryonic stages. Peptidoglycan injections strongly induce five of the genes. Transcripts from the different PGRP genes were found in immune competent organs such as fat body, gut, and hemocytes. We demonstrate that at least PGRP-SA and SC1B can bind peptidoglycan, and a function in immunity is likely for this family.

Amino Acid Sequence↗

PubMed2000

Molecular cloning, genomic organization, and mapping of PRKAG2, a heart abundant gamma2 subunit of 5'-AMP-activated protein kinase, to human chromosome 7q36.

5'-AMP-activated protein kinase (AMPK) acts as a major regulator of cellular ATP levels and protects cells against stresses that cause ATP depletion. AMPK is a protein heterotrimer composed of a catalytic alpha subunit and two regulatory subunits, beta and gamma. In the present study, a homologue of the AMPK gamma1-subunit cDNA with an open reading frame encoding 328 amino acids was identified. The putative protein sequence is about 76% identical to the 331-amino-acid gamma1 subunit and also has four consecutive cystathionine-beta-synthase (CBS) domains, a characteristic structure of AMPK gamma subunits from various species. This cDNA (tentatively termed PRKAG2-b) is identical to a recently reported cDNA (tentatively termed PRKAG2-a) of human AMPK gamma subunits except in their 5'-end regions, suggesting that these two cDNAs are two different transcripts of the same gene. To determine the expression pattern of the gene, two probes, one from the 3'-UTR of PRKAG2-b and the other from the 5'- unique region of PRKAG2-a, were used to hybridize MTN membranes. Three transcripts (3.8, 3.0, and 2.4 kb) were observed when the first probe was used, whereas only 3.8- and 3.0-kb transcripts were seen when the second probe was used. Thus, the PRKAG2-b corresponded to the 2.4-kb transcript, which is ubiquitously expressed except in liver and thymus. The highest level was detected in heart, while abundant expression also existed in placenta and testis. The expression pattern of PRKAG2-b is completely different from those of PRKAG2-a and PRKAG1, whose expression patterns were also determined in the current study. The PRKAG2 gene was located to human chromosome 7q36 between markers D7S2439 and D7S2462 by radiation hybrid mapping. The genomic organization of PRKAG2-b was identified by comparing its cDNA sequence with two genomic sequences AC006358 and AC006966, which showed that PRKAG2-b spanned an approximately 80-kb region and was composed of 12 exons.

AMP-Activated Protein Kinases↗

PubMed2000

Transmembrane redox sensor of ryanodine receptor complex.

Inositol 1,4,5-trisphosphate receptors (IP(3)R) and ryanodine receptors (RyR) mediate the release of endoplasmic and sarcoplasmic reticulum (ER/SR) Ca(2+) stores and regulate Ca(2+) entry through voltage-dependent or ligand-gated channels of the plasma membrane. A prominent property of ER/SR Ca(2+) channels is exquisite sensitivity to sulfhydryl-modifying reagents. A plausible role for sulfhydryl chemistry in physiologic regulation of Ca(2+) release channels and the fidelity of Ca(2+) release from ER/SR is lacking. This study reveals the existence of a transmembrane redox sensor within the RyR1 channel complex that confers tight regulation of channel activity in response to changes in transmembrane redox potential produced by cytoplasmic and luminal glutathione. A transporter selective for glutathione is co-localized with RyR1 within the SR membrane to maintain local redox potential gradients consistent with redox regulation of ER/SR Ca(2+) release. Hyperreactive sulfhydryls previously shown to reside within the RyR1 complex (Liu, G., and Pessah, I. N. (1994) J. Biol. Chem. 269, 33028-33034) are an essential biochemical component of a transmembrane redox sensor. Transmembrane redox sensing may represent a fundamental mechanism by which ER/SR Ca(2+) channels respond to localized changes in transmembrane glutathione redox potential produced by physiologic and pathophysiologic modulators of Ca(2+) release from stores.

Animals↗

PubMed2000

Down-regulation of the Diphthamide biosynthesis protein 2-like gene during retinoid-induced differentiation and apoptosis: implications against its tumor-suppressor activity.

Retinoids, synthetic and natural analogs of retinoic acid (RA) have profound effects on the proliferation and differentiation of many cell types; this accounts for their beneficial effects in the treatment of certain neoplasias. We have employed mRNA differential display to characterize genes associated with differentiation and apoptosis induced by all-trans RA in human lung cancer cells. We have identified a cDNA corresponding to the sequence of the known gene diphthamide biosynthesis protein 2-like (DPH2L). Although the function of this gene remains unknown, as it was first isolated from the critical region of deletion on chromosome 17p13.3 in human ovarian carcinoma, it has been regarded as a candidate tumor-suppressor gene. In this report, we provide evidence that DPH2L is down-regulated during differentiation or apoptosis in several cancer cell lines after treatment with all-trans RA or N-(4-hydroxyphenyl)retinamide and during cell-cycle arrest. Moreover, stable expression of DPH2L-specific anti-sense construct leads to inhibition of cell proliferation. Our results suggest that DPH2L in not a conventional tumor-suppressor gene. Instead, it may be a growth regulator and its down-regulation might be permissive for the transition from cell growth to differentiation or apoptosis. DPH2L might be a useful tool in the prognosis of neoplastic diseases.

Adenosine Diphosphate Ribose↗

PubMed2000

Discovery of novel p-arylthio cinnamides as antagonists of leukocyte function-associated antigen-1/intracellular adhesion molecule-1 interaction. 1. Identification of an additional binding pocket based on an anilino diaryl sulfide lead.

The interaction between leukocyte function-associated antigen-1 (LFA-1), a member of the beta(2)-integrin family of adhesion molecules, and intracellular adhesion molecule ICAM-1 (cd54) is thought to play a critical role in the inflammatory process. On the basis of an anilino diaryl sulfide screening lead 1, in combination with pharmacophore analysis of other screening hits, we have identified an adjacent binding pocket. Subsequently, a p-ethenylcarbonyl linker was discovered to be optimal for accessing this binding site. Solution-phase parallel synthesis enabled rapid optimization of the cinnamides for this pocket. In conjunction with fine-tuning of the diaryl substituents, we discovered a novel series of potent, nonpeptide inhibitors of LFA-1/ICAM-1 interaction, exemplified by A-286982 (28h), which has IC(50) values of 44 and 35 nM in an LFA-1/ICAM-1 binding assay and LFA-1-mediated cellular adhesion assay, respectively.

Animals↗

PubMed2000

Lipoprotein lipase activity is associated with severity of angina pectoris. REGRESS Study Group.

BACKGROUND: Raised triglyceride-rich lipoproteins significantly increase the risk for cardiovascular disease. Variation in the activity of the enzyme lipoprotein lipase (LPL), which is crucial in the removal of these lipoproteins, may therefore modulate this risk. METHODS AND RESULTS: Postheparin levels of LPL activity and mass were measured in a large cohort of male coronary artery disease patients participating in the Regression Growth Evaluation Statin Study (REGRESS), a lipid-lowering regression trial. In addition, the relationships between LPL activity and mass and severity of angina pectoris according to the NYHA classification and silent ischemia on 24-hour ambulatory ECG monitoring were assessed. Patients in different LPL activity quartiles and mass had different severities of angina; a total of 47% of patients in the lowest LPL quartile reported class III or IV angina. In contrast, only 29% in the highest activity quartile (P:=0.002) had severe angina. These parameters were supported by ambulatory ECG results, for which the total ischemic burden in the lowest LPL activity quartile was 36. 5+/-104.1 mm x min compared with 14.8+/-38.8 mm x min in the highest quartile of LPL activity (P:=0.001). LPL activity levels were strongly correlated with LPL mass (r=0.70, P:<0.0001). A significant association between the LPL protein mass and NYHA class (P:=0.012) was also demonstrated. CONCLUSIONS: We have demonstrated a significant relationship between LPL mass and activity and severity of ischemia as defined by angina class and ambulatory ECG. These results suggest that LPL influences risk for coronary artery disease by both catalytic and noncatalytic mechanisms.

Aged↗

PubMed2000

Assessment of physical activity with a single global question in a large, multiethnic sample of midlife women.

This study compared responses from 13,621 African-American, Chinese, Hispanic, Japanese, and White women to a single, global physical activity question. Respondents aged 40-55 years were randomly selected from seven geographic locations in the United States for the 1996-1997 cross-sectional survey of the Study of Women's Health Across the Nation, a longitudinal, observational study of the menopause transition. Respondents rated their activity level as much less, less, the same as, more, or much more than other women their age. Physical activity rating varied minimally by race/ethnicity. The proportions of women who rated themselves much less active and much more active ranged from 3.1% for Whites to 4.8% for Japanese and from 13.6% for Japanese to 16.4% for African Americans, respectively. Multiple logistic regression models, stratified by race/ethnicity, showed independent associations between a low level of activity and higher body mass index, poor health, functional impairment, perceived stress, difficulty sleeping, and not being employed. A high level of activity was associated with excellent health, single marital status, higher education, lower body mass index, and older age. These findings suggest that a comparative rating of physical activity may rank women by activity level within a specific racial/ethnic group but may not capture differences across racial/ethnic groups.

Adult↗

PubMed2000

Refinement of the locus for autosomal dominant hereditary gingival fibromatosis (GINGF) to a 3.8-cM region on 2p21.

Hereditary gingival fibromatosis (HGF, MIM 135300; approved gene symbol GINGF) is an oral disease characterized by enlargement of gingiva. Recently, a locus for autosomal dominant HGF has been mapped to an 11-cM region on chromosome 2p21. In the current investigation, we genotyped four Chinese HGF families using polymorphic microsatellite markers on 2p21. The HOMOG test provided evidence for genetic homogeneity, with evidence for linkage in four families (heterogeneity versus homogeneity test HOMOG, chi(2) = 0. 00). A cumulative maximum two-point lod score of 5.04 was produced with marker D2S390 at a recombination frequency of θ = 0 in the four linked families. Haplotype analysis localized the hereditary gingival fibromatosis locus within the region defined by D2S352 and D2S2163. This region overlaps by 3.8 cM with the previously reported HGF region. Single-strand conformation polymorphism and sequence analysis of the coding region of cytochrome P450 1B1 (CYP1B1) excluded it as a likely candidate gene.

Aryl Hydrocarbon Hydroxylases↗

PubMed2000

Fully processed lysyl oxidase catalyst translocates from the extracellular space into nuclei of aortic smooth-muscle cells.

Lysyl oxidase (LO), a secreted protein, was recently identified within the nuclei of vascular smooth-muscle cells (SMC) and 3T3 fibroblasts. A possible pathway by which LO can enter cell nuclei was explored in the present study. SMC were incubated with purified 32-kDa bovine aorta LO that had been fluorescently labeled with rhodamine (TRITC-LO). TRITC-LO entered the cytosol and then rapidly concentrated within the nuclei of preconfluent cultures of these cells, whereas carbonic anhydrase, a protein of similar molecular weight and similarly labeled, did not enter the cells under these conditions. LO that had been reductively methylated at lysine residues with [(14)C]HCHO was also taken up into the cytosolic and nuclear compartments. Intracellular uptake and intracellular distribution were not altered by inhibiting LO activity with beta-aminopropionitrile. An excess of native LO but not of carbonic anhydrase competitively inhibited the uptake of the isotopically labeled enzyme. Thus, once secreted and proteolytically processed, mature LO can enter the cells and concentrate within nuclei in a manner that appears to be specific and independent of its catalytic activity.

3T3 Cells↗

PubMed2000

Novel synthesis of photochromic polymers via ROMP.

[reaction: see text] Ring-opening metathesis polymerization (ROMP) of a photochromic 1, 2-bis(3-thienyl)cyclopentene monomer generated a series of novel polymers. All polymers exhibit reversible light-activated interconversion between their colorless-open and their colored-closed forms.

Journal Article↗