Biomedical subjects

J Hu

Publications and source records attributed to J Hu.

At least 199 records · Page 11Linked to original sources

PubMed2001

[Study on the direct interaction between aminoacylase and Cu(II) ions by spectroscopic analysis].

In this paper, the method of reconstitution was used to investigate the interaction between metalloenzymes (containing Zn (II) and metal ions. Electron paramagnetic resonance(EPR), visible spectrum (Vis) and enzyme activity assay have been employed to study the direct interactions between aminoacylase (ACY) and Cu(II) ions added in aqueous solution. The results show that a dynamic equilibrium exists between the Zn(II) in the active site of native enzymes and the added Cu(II), the added Cu(II) partly replaces the Zn(II), forming Cu(II)-enzyme derivatives. As a result, the activity of the native enzymes is influenced. In addition, the influences of pH value on this kind of interaction have also been investigated, and the results demonstrate that the decrease in the intensity of the Cu (II) EPR signal and the change of place signal in Vis were observed as increase of pH value. These results suggest that the derivative of Cu(II)-ACY exists in solution with two different conformations, and this two conformations exchanged each other depending on pH.

Alkaline Phosphatase↗

PubMed2001

[Clinical significance of antibiotic prophylaxis for transrectal prostate biopsy].

OBJECTIVE: To evaluate the efficacy and safety of single-dose oral antibiotic prophylaxis in the METHODS: Between prevention of post-procedure infections in patients undergoing transrectal prostate biopsy. September 1998 and March 2001, a total of 192 patients who had an abnormal digital rectal examination and/or prostate specific antigen 4 ng/ml or greater underwent transrectal ultrasound guided systematic 13 cores prostate biopsy. The patients were randomly divided into three groups. Group A (62) received a placebo (Vit C) tablet twice a day for 3 days, group B (64) a single dose of ciprofloxacin (0.5 g) and metronidazole (0.4 g), and group C (66) the same combination twice a day for 3 days. Urine cultures were obtained 48 h after the biopsy and blood cultures when patients who developed fever. RESULTS: Noninfective complications included were rectal bleeding, haematuria and pain. Infective complications included urinary tract infection and fever. There was no significant difference among the three groups in noninfective complications but the incidence of infective complications in group A was significantly higher than in groups B and C (P < 0.01). There was no significant difference among group B and C in infective complications (P > 0.05). CONCLUSIONS: Our study shows single-dose oral antibiotic prophylaxis is effective and safe to prevent infectious complications follow transrectal prostate biopsy.

Aged↗

PubMed2001

[Prognosis of patients with primary liver carcinoma treated with local resection].

OBJECTIVE: To discuss the prognosis of primary liver carcinoma treated with local resection and factors affecting prognosis. METHODS: The data on 130 patients who had been treated from October 1989 to October 1995 were reviewed retrospectively. RESULTS: Curative local resection was performed in 130 patients. Death rate of operation was 0.7%, and the incidence of complications 16.1% (n = 18). The overall 1-, 3- and 5-year survival rates were 82.1%, 60.6% ,48.2%, respectively. Involvement of blood vessels or liver capsules as well as the increase of AST before operation are the significant factors affecting prognosis (P < 0.05). CONCLUSIONS: Local resection is a method characterized by little damage, less bleeding, less complication and good prognosis.

Adult↗

PubMed2000

Enhanced delivery of AZT to macrophages via acetylated LDL.

It is known that infected macrophages play an important role in HIV pathogenesis acting as a reservoir for dissemination of the virus to various organs. Enhanced and/or specific delivery of anti-HIV agents to infected cells is expected to improve their therapeutic index by increasing efficacy and reducing toxicity. Acetylated low density lipoproteins (AcLDL) are known to be taken up by macrophages via scavenger receptors and appear to be good carriers for targeting drug molecules to macrophages. This study investigated the delivery of 3'-azido-3'-deoxythymidine (AZT), an anti-HIV agent, to macrophages using AcLDL. Since the incorporation of AZT into AcLDL was found to be low, several derivatives of AZT including 5'-O-13-oxamyristate-AZT (5'-O-oxaMyr-AZT) have been synthesized as prodrugs. The prodrugs were incorporated into AcLDL using two different methods, namely the contact method and the microemulsion method. Our results demonstrated that the microemulsion method was more effective. The physicochemical properties of the AcLDL/prodrug complex were evaluated by electrophoresis and electron microscopy (EM). Incubation of the complex with plasma resulted in little distribution of the incorporated drug molecules from AcLDL to other components of the plasma, suggesting that the complex was quite stable. Cellular uptake studies using J774.A and U937 demonstrated that AcLDL/prodrug was taken up about 10 times more than AZT. The presence of excess AcLDL was found to inhibit the cellular uptake of AcLDL/5'-O-oxaMyr-AZT by macrophages while excess high density lipoprotein (HDL) or low density lipoprotein (LDL) was found to have little effect, suggesting that the AcLDL/prodrug complex is taken up into macrophages via the scavenger receptor.

Animals↗

PubMed2000

Impaired endothelial function and increased carotid stiffness in 9-year-old children with low birthweight.

BACKGROUND: Low birthweight (LBW) has been associated with an increased incidence of adult cardiovascular disease. Endothelial dysfunction and loss of arterial elasticity are early markers of hypertension and atherosclerosis. We studied the prevalence of these markers in 44 healthy, prepubertal (age 9+/-1.3 years) children, 22 with LBW for age. METHODS AND RESULTS: Endothelial function in skin was tested with the local application of acetylcholine (inducing endothelium-dependent vasodilation) and nitroglycerin (endothelium-independent vasodilation), and local perfusion changes were measured with the laser Doppler method. The elastic properties of the abdominal aorta and common carotid artery were measured with an ultrasonic vessel-wall tracking system. Endothelium-dependent vasodilation was lower in children with LBW (88+/-33 perfusion units [PU]) than in normal-birthweight controls (133+/-34 PU, P<0.001). There was no difference in aortic or carotid elasticity between the 2 groups, but a negative correlation was found between birthweight and stiffness of the carotid artery wall (r=-0.45, P<0.01). Endothelium-independent vasodilation and blood pressure were similar in the 2 groups. CONCLUSIONS: Schoolchildren with a history of LBW show impaired endothelial function and a trend toward increased carotid stiffness. These findings may be early expressions of vascular compromise, contributing to susceptibility to disease in adult life.

Acetylcholine↗

PubMed2000

Expression of functional formyl peptide receptors by human astrocytoma cell lines.

Activation of astrocytes is important in the pathogenesis of a variety of diseases in the central nervous system, such as infection and neurodegeneration. We found that the bacterial chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLF) induced potent migration and Ca(2+) mobilization in human astrocytoma cell lines. The effect of fMLF was pertussis toxin-sensitive, suggesting the involvement of seven transmembrane, G protein-coupled receptor(s) for fMLF. Scatchard analyses revealed that astrocytoma cell lines express both high- and low-affinity binding sites for [3H]fMLF. RT-PCR confirmed the expression of transcripts of fMLF receptors, the high-affinity FPR and the low-affinity FPRL1 by these cells. Both fMLF and F peptide, a synthetic peptide domain of HIV-1 envelope protein which specifically activates FPRL1, increased secretion of IL-6 by astrocytoma cells. Our study demonstrates for the first time that FPR and FPRL1 expressed by astrocytoma cell lines are functional, and suggests a molecular basis for the involvement of these receptors in host defense in the brain.

Astrocytoma↗

PubMed2000

Fourier-transform Raman and infrared spectroscopic analysis of novel biliverdin compounds.

The vibrational spectroscopy of novel biliverdin compounds were studied by Fourier-transform Raman (FT-Raman) and infrared (FT-IR) spectroscopy. The effects of type, length and position of substituents at C(8) and C(12) or C(1) and C(19) of tetrapyrroles on FT-Raman and FT-IR spectra of these compounds, are discussed. The marker bands are developed in order to distinguish between etiobiliverdin and mesobiliverdin.

Biliverdine↗

PubMed2000

Apolipoprotein E receptors mediate the effects of beta-amyloid on astrocyte cultures.

We have previously shown that beta-amyloid (Abeta) induces astrocyte activation in vitro and that this reaction is attenuated by the addition of exogenous apolipoprotein E (apoE)-containing particles. However, the effects of Abeta on endogenous apoE and apoJ levels and the potential role of apoE receptors in astrocyte activation have not been addressed. Three activating stimuli (lipopolysaccharide, dibutyryl cAMP, and aged Abeta 1-42) were used to induce activation of rat astrocyte cultures, as assessed by changes in morphology and an increase in interleukin-1beta. However, only Abeta also induced approximately 50% reduction in the amount of released apoE and apoJ and an 8-fold increase in the levels of cell-associated apoE and apoJ. Experiments using two concentrations of receptor-associated protein, an inhibitor of apoE receptors with a differential affinity for the low density lipoprotein receptor (LDLR) and the LDLR-related protein (LRP), suggest that LRP mediates Abeta-induced astrocyte activation, whereas LDLR mediates the Abeta-induced changes in apoE levels. Receptor-associated protein had no effect on apoJ levels or on activation by either dibutyryl cAMP or lipopolysaccharide. These data suggest that apoE receptors translate the presence of extracellular Abeta into cellular responses, both initiating and modulating the inflammatory response induced by Abeta.

Amyloid beta-Peptides↗

PubMed2000

Interleukin-1beta increases binding of the iron regulatory protein and the synthesis of ferritin by increasing the labile iron pool.

This study was undertaken to begin to elucidate the mechanisms by which cytokines influence intracellular iron homeostasis. Intracellular iron homeostasis is maintained by the coordinated regulation of ferritin and transferrin receptor synthesis. The synthesis of these proteins is coordinated by cytoplasmic iron regulatory proteins (IRP), which bind to iron responsive elements (IRE) on their mRNAs. We evaluated the effects of interleukin-1beta (IL-1beta) on iron metabolism in human astrocytoma cells (SW1088). Exposure to IL-1beta for 16 h increased binding of the IRPs to the IRE and also increased ferritin synthesis. Using the iron sensitive dye calcein, we determined that the intracellular labile iron pool increased within 4 h of IL-1beta exposure and continued to increase for 8 h, returning to normal by 16 h. We propose that the cytokine induced increase in the labile iron pool stimulates ferritin synthesis resulting in a subsequent decrease in the labile iron pool. The decrease in the labile iron pool is consistent with the increase in IRE/IRP interaction measured at 16 h. These results indicate that cytokines can influence the labile iron pool and the post-transcriptional regulatory mechanism for maintaining iron homeostasis. These results contribute to understanding the response of ferritin to inflammation by suggesting ferritin synthesis may reflect changes in the labile iron pool. The approach used in this study may provide a model system for studying relations between the labile iron pool and proteins responsible for maintaining intracellular homeostasis

Aconitate Hydratase↗

PubMed2000

Regulation of gene expression of murine MD-1 regulates subsequent T cell activation and cytokine production.

The immunoadhesin (OX2:Fc) comprising the extracellular domain of murine OX2 linked to IgG2aFc, inhibits production of IL-2 and IFN-gamma by activated T cells and increases allograft and xenograft survival in vivo. Increased expression of OX2 on dendritic cells (DC) in vivo following preimmunization via the portal vein is also associated with elevated expression of MD-1. We have used antisense oligodeoxynucleotides (ODNs) to MD-1 to investigate the effect of inhibition of expression of MD-1 by DC on their function as allostimulatory cells. We also investigated by FACS analysis the cell surface expression of OX2, CD80, and CD86 on DC incubated with ODN-1 blocking MD-1 expression. Blocking MD-1 gene expression inhibits surface expression of CD80 and CD86, but not of OX2. DC incubated with ODN-1 to MD-1 did not stimulate IL-2 or IFN-gamma production, but generated cells able to suppress, in a second culture of fresh DC plus allogeneic T cells, production of IL-2 and IFN-gamma. This inhibition was blocked by anti-OX2 mAb. Infusion of DC preincubated with ODN-1 prolonged renal allograft survival, an effect also reversed by anti-OX2 mAb. By FACS, incubation of DC with anti-MD-1 Ab to promote capping eliminated cell surface expression of MD-1 and CD14 without altering DEC205, DC26, CD80, CD86, or OX2 expression. Thus OX2 and MD-1 are independent surface molecules on DC that may reciprocally regulate T cell stimulation. MD-1 is linked to CD14, a "danger receptor complex," and activation of this complex can regulate cell surface expression of CD80/CD86, which signal T cells.

Animals↗

PubMed2000

Characterization of interleukin-1 receptor-associated kinase in normal and endotoxin-tolerant cells.

Interleukin-1 receptor-associated kinase (IRAK), a signal transducer for interleukin-1, has also been suggested to participate in the Toll-like receptor-mediated innate immune response to bacterial endotoxin lipopolysaccharide (LPS). Using the human promonocytic THP-1 cell line, we demonstrated that the endogenous IRAK is quickly activated in response to bacterial LPS stimulation, as measured by its in vitro kinase activity toward myelin basic protein. LPS also triggers the association of IRAK with MyD88, the adaptor protein linking IRAK to the Toll-like receptor/interleukin-1beta receptor intracellular domain. Macrophage cells with prolonged LPS treatment become tolerant to additional dose of LPS and no longer express inflammatory cytokines. Endotoxin tolerance is a common phenomenon observed in blood from sepsis patients. We observed for the first time that the quantity of IRAK is greatly reduced in LPS-tolerant THP-1 cells, and its activity no longer responds to further LPS challenge. In addition, IRAK does not associate with MyD88 in the tolerant cells. Furthermore, application of AG126, a putative tyrosine kinase inhibitor, can substantially alleviate the LPS-induced cytokine gene expression and can also decrease IRAK level and activity. Our study indicates that IRAK is essential for LPS-mediated signaling and that cells may develop endotoxin tolerance by down-regulating IRAK.

Adaptation, Physiological↗

PubMed2000

Multiple roles for the twin arginine leader sequence of dimethyl sulfoxide reductase of Escherichia coli.

Dimethyl sulfoxide (Me(2)SO) reductase of Escherichia coli is a terminal electron transport chain enzyme that is expressed under anaerobic growth conditions and is required for anaerobic growth with Me(2)SO as the terminal electron acceptor. The trimeric enzyme is composed of a membrane extrinsic catalytic dimer (DmsAB) and a membrane intrinsic anchor (DmsC). The amino terminus of DmsA has a leader sequence with a twin arginine motif that targets DmsAB to the membrane via a novel Sec-independent mechanism termed MTT for membrane targeting and translocation. We demonstrate that the Met-1 present upstream of the twin arginine motif serves as the correct translational start site. The leader is essential for the expression of DmsA, stability of the DmsAB dimer, and membrane targeting of the reductase holoenzyme. Mutation of arginine 17 to aspartate abolished membrane targeting. The reductase was labile in the leader sequence mutants. These mutants failed to support growth on glycerol-Me(2)SO minimal medium. Replacing the DmsA leader with the TorA leader of trimethylamine N-oxide reductase produced a membrane-bound DmsABC with greatly reduced enzyme activity and inefficient anaerobic respiration indicating that the twin arginine leaders may play specific roles in the assembly of redox enzymes.

Amino Acid Sequence↗

PubMed2000

Interleukin-6 modulates interferon-regulated gene expression by inducing the ISGF3 gamma gene using CCAAT/enhancer binding protein-beta(C/EBP-beta).

Although interleukin-6 (IL-6) alone does not induce the expression of IFN stimulated genes (ISG), a low dose priming of cells with IL-6 strongly enhances the cellular responses to interferon-alpha (IFN-alpha). This effect of IL-6 is not due to superstimulation of the JAK-STAT pathway. Rather, IL-6 induces expression of ISGF3 gamma (p48), a subunit of the multimeric transcription factor ISGF3. As a result IFN-alpha robustly activates gene transcription in IL-6 primed cells. We have shown earlier that the transcription of ISGF3 gamma gene is regulated through a novel element GATE (gamma-IFN activated transcriptional element). We show here IL-6 induces the ISGF3 gamma gene through GATE. Transcription factor C/EBP-beta is required for inducing ISGF3 gamma gene expression through GATE. A mutant C/EBP-beta inhibits the IL-6 inducible ISGF3 gamma gene expression through GATE. Together, these results establish a molecular basis for the synergy between IFNs and IL-6.

CCAAT-Enhancer-Binding Protein-beta↗

PubMed2000

Identification and characterization of cell lines with a defect in a post-adsorption stage of Sendai virus-mediated membrane fusion.

In the early stage of infection, Sendai virus delivers its genome into the cytoplasm by fusing the viral envelope with the cell membrane. Although the adsorption of virus particles to cell surface receptors has been characterized in detail, the ensuing complex process that leads to the fusion between the lipid bilayers remains mostly obscure. In the present study, we identified and characterized cell lines with a defect in the Sendai virus-mediated membrane fusion, using fusion-mediated delivery of fragment A of diphtheria toxin as an index. These cells, persistently infected with the temperature-sensitive variant Sendai virus, had primary viral receptors indistinguishable in number and affinity from those of parental susceptible cells. However, they proved to be thoroughly defective in the Sendai virus-mediated membrane fusion. We also found that viral HN protein expressed in the defective cells was responsible for the interference with membrane fusion. These results suggested the presence of a previously uncharacterized, HN-dependent intermediate stage in the Sendai virus-mediated membrane fusion.

Animals↗

PubMed2000

Three novel TBX5 mutations in Chinese patients with Holt-Oram syndrome.

Holt-Oram syndrome (HOS) is an autosomal dominant syndrome that comprises upper limb and cardiac defects. The gene responsible for HOS, TBX5, was isolated and many mutations have been identified in HOS patients. We analyzed 11 Chinese HOS patients (7 from three families and 4 sporadic cases) for TBX5 mutation by single strand conformation polymorphisms (SSCPs). Three SSCP changes were detected in two of the three familial cases and one sporadic case. Sequence analysis identified three novel, heterozygous mutations in TBX5: a frameshift mutation caused by one base deletion [C416del] in one family, a mis-sense mutation (Gln49Lys) induced by a base substitution (C145A) in another family, and the other mis-sense mutation (Ile54Thr) by T161C in one sporadic case. The patients with the frameshift mutations had severer clinical manifestations that involved aplasia/hypoplasia of the arm and thumbs, while those with the mis-sense mutations presented with milder anomalies such as absent or hypoplastic thumbs but without arm abnormalities. These observations may support a genotype-phenotype correlation in HOS patients with TBX5 mutation.

Amino Acid Substitution↗

PubMed2000

[Determination of trichlosan in cosmeticy by high-performance liquid chromatography].

A method was developed for the determination of an antiseptic-trichlosan in cosmeticy by HPLC followed by diode-array detection. The chromatographic separation was performed on C18 column with a mobile phase of acetonitrile-water(60: 40, V/V) which was adjusted to pH3.0 by glacialacetic acid. The UV wavelength was 280 nm. Retention time as well as UV spectrum were used for the qualitation of trichlosan, and peak area or peak height for quantitation. The method showed good accuracy and precision average recovery of trichlosan from different cosmetics was between 91.86% and 98.83%. Relative standard deviation was between 0.72% and 2.75%.

Anti-Infective Agents, Local↗

PubMed2000

Human Ca2+ receptor cysteine-rich domain. Analysis of function of mutant and chimeric receptors.

The 612-residue extracellular domain of the human Ca(2+) receptor (hCaR) has been speculated to consist of a Venus's-flytrap domain (VFT) and a cysteine-rich domain. We studied the function of the hCaR Cys-rich domain by using mutagenesis and chimera approaches. A chimeric hCaR with the sequence from residues 540-601 replaced by the corresponding sequence from the Fugu CaR remained fully functional. Another chimeric hCaR with the same region of sequence replaced by the corresponding sequence from metabotropic glutamate receptor subtype 1 (mGluR1) still was activated by extracellular Ca(2+) ([Ca(2+)](o)), but its function was severely compromised. Chimeric receptors with the hCaR VFT and mGluR1 seven-transmembrane domain plus C-tail domain retained good response to [Ca(2+)](o) whether the Cys-rich domain was from hCaR or from mGluR1. Mutant hCaR with the Cys-rich domain deleted failed to respond to [Ca(2+)](o), although it was expressed at the cell surface and capable of dimerization. Our results indicate that the hCaR Cys-rich domain plays a critical role in signal transmission from VFT to seven-transmembrane domain. This domain tolerates a significant degree of amino acid substitution and may not be directly involved in the binding of [Ca(2+)](o).

Amino Acid Sequence↗

PubMed2000

CCAAT/enhancer-binding protein-beta regulates interferon-induced transcription through a novel element.

We have described previously a novel interferon (IFN)-responsive cis-acting enhancer element called gamma-IFN-activated transcriptional element (GATE). GATE is distinct from the known IFN-stimulated elements and binds to novel transacting factors. To identify the gamma-IFN-responsive transacting factors that interact with GATE, we have screened a cDNA expression library derived from IFN-gamma-stimulated murine macrophage cell line and isolated three different cDNAs. Among these is a gene coding for the pleiotropic transcription factor, CCAAT/enhancer-binding protein-beta (C/EBP-beta). We report here that the gene for C/EBP-beta binds to GATE and induces gene expression. A mutant C/EBP-beta interferes with the IFN-gamma-stimulated transcription of the ISGF3gamma (p48) promoter. Other members of the C/EBP family do not cause these effects. Interestingly, the expression of C/EBP-beta, not the other members of its family, is induced by IFN-gamma. These studies thus identify a novel role for C/EBP-beta in the IFN-signaling pathways.

Animals↗