Biomedical subjects

H Wang

Publications and source records attributed to H Wang.

At least 451 records · Page 25Linked to original sources

PubMed2001

Fetuin, a negative acute phase protein, attenuates TNF synthesis and the innate inflammatory response to carrageenan.

Activation of the innate immune system, even by relatively innocuous stimuli, stimulates the release of cytokines (e.g. TNF) that can injure or kill the host. To maintain homeostasis, mammals have evolved a counter-regulatory response that suppresses the development of excessively robust inflammation. Fetuin, a 66-kD negative acute phase glycoprotein, was first identified in 1944. We recently discovered an anti-inflammatory role for fetuin, because it suppressed the release of TNF from lipopolysaccharide- (LPS) stimulated macrophages. Here the anti-inflammatory effects of fetuin were studied in vivo in an LPS-independent model of acute inflammation caused by administration of carrageenan. Administration of fetuin (5-500 mg/kg intraperitoneally) dose-dependently attenuated the development of paw edema as compared to either asialofetuin (500 mg/kg) or bovine albumin (500 mg/kg). TNF production in the carrageenan-injected paws was significantly inhibited by administration of fetuin (586+/-98 pg TNF/paw) as compared to either asialofetuin (1018+/-186 pg TNF/paw) or saline (1,005+/-172 pg TNF/paw). When specific anti-fetuin IgG was administered into the paw prior to the application of carrageenan, the development of edema formation was significantly increased as compared to irrelevant IgG, indicating that endogenous fetuin normally attenuates the inflammatory response. These results now reveal a previously unrecognized anti-inflammatory role of fetuin in counter-regulating the innate immune response, and suggest that it may be possible to use fetuin as an experimental anti-inflammatory agent.

Acute-Phase Proteins↗

PubMed2001

HMG-1 rediscovered as a cytokine.

High-mobility group-1 (HMG-1), an abundant, highly conserved cellular protein, is widely known as a nuclear DNA-binding protein that stabilizes nucleosome formation, facilitates gene transcription, and regulates the activity of steroid hormone receptors. We discovered that HMG-1 is a late mediator of delayed endotoxin lethality. When released by activated monocytes, it participates in the development of lethality and it activates downstream cytokine release. This review covers the general features of HMG-1 and its newly appreciated role as a cytokine.

Acute-Phase Reaction↗

PubMed2001

Gene expression profiles during the initial phase of salt stress in rice.

Transcript regulation in response to high salinity was investigated for salt-tolerant rice (var Pokkali) with microarrays including 1728 cDNAs from libraries of salt-stressed roots. NaCl at 150 mM reduced photosynthesis to one tenth of the prestress value within minutes. Hybridizations of RNA to microarray slides probed for changes in transcripts from 15 min to 1 week after salt shock. Beginning 15 min after the shock, Pokkali showed upregulation of transcripts. Approximately 10% of the transcripts in Pokkali were significantly upregulated or downregulated within 1 hr of salt stress. The initial differences between control and stressed plants continued for hours but became less pronounced as the plants adapted over time. The interpretation of an adaptive process was supported by the similar analysis of salinity-sensitive rice (var IR29), in which the immediate response exhibited by Pokkali was delayed and later resulted in downregulation of transcription and death. The upregulated functions observed with Pokkali at different time points during stress adaptation changed over time. Increased protein synthesis and protein turnover were observed at early time points, followed by the induction of known stress-responsive transcripts within hours, and the induction of transcripts for defense-related functions later. After 1 week, the nature of upregulated transcripts (e.g., aquaporins) indicated recovery.

Adaptation, Physiological↗

PubMed2001

Computer-aided dynamic simulation of microwave-induced thermal distribution in coagulation of liver cancer.

To develop a method of dynamic three-dimensional (3-D) simulation of thermal distribution in ultrasound-guided microwave coagulation therapy of liver cancer and to verify its accuracy. The specific absorption rate (SAR) values were established by measuring the temperature in equivalent phantom tests. Those values were different under different power output condition. Dynamic 3-D temperature distributions were reconstructed with a finite-element model. Testing and rectification were performed through animal experiments and clinical trials, respectively. The temperature curves in the experiments corresponded well with simulated ones in vitro--91.4% and 88.9% using single and double electrodes, respectively. The measured coagulated boundary and simulated temperature boundary had a good correspondence in 85.7% of the specimens. In both in vivo experiments and clinical trials, blood perfusion influenced the rise in temperature significantly. Temperature curves between the simulations and actual measured results showed good correspondence--67.8% (19/28) in the patients with hepatocellular carcinoma. Distance between electrodes and combined thermal distributions were both optimized with computer-aided simulation during simultaneous two-electrode coagulation. The results demonstrated that computer-aided simulation of microwave thermal distribution is an accurate and reliable method which provides a theoretical and technical basis for controlling coagulated tissue volume and placement of the electrodes during microwave coagulation therapy of liver cancer.

Animals↗

PubMed2001

High frequency properties of passive materials for ultrasonic transducers.

The acoustic properties of passive materials for ultrasonic transducers have been measured at room temperature in the frequency range from 25 to 65 MHz using ultrasonic spectroscopy. These materials include alumina/EPO-TEK 301 composites and tungsten/EPO-TEK 301 composites. Experimental results showed that the acoustic impedance of the composites monotonically increased with the volume fraction of the particle filler, which is in agreement with the Denavey model. The attenuation, however, peaked between 7 and 9% volume fraction of particle filler. For comparison, several other passive materials were also fabricated and measured. The results suggest that materials that possess a higher attenuation also appear to have a larger velocity dispersion.

Aluminum Oxide↗

PubMed2001

Improved ultrasonic spectroscopy methods for characterization of dispersive materials.

Transmission ultrasonic spectroscopy method has been successfully implemented for the characterization of piezoceramics at high frequencies. There are, however, still some intrinsic error sources that limit the accuracy of the method. In this paper, two improved ultrasonic spectroscopy methods are presented, which can reduce the number of pre-required parameters and reduce another error source. The two improved methods were used to measure the frequency dispersion of phase velocity and attenuation of doped piezoceramic lead zirconate titanate (PZT-5A); results were compared with those obtained from the conventional method. The advantages and limitations of each method are discussed.

Biomedical Engineering↗

PubMed2001

Stem cell engraftment strategies.

The donor stem cell phenotype and host microenvironment determine the outcome of a stem cell transplant. In a series of transplant studies in syngeneic male to female or congenic Ly5.1/Ly5.2 models in which hosts have received no or minimal irradiation (100 cGy), evidence overwhelmingly supports the concept that syngeneic engraftment is determined by stem cell competition. These approaches can be extended to H-2 mismatched allogeneic mouse combination when antigen pre-exposure and CD40-CD40 ligand antibody blockage are employed. A human trial in patients with resistant neoplasia infusing pheresed blood with 10(8) CD3 cells/kg showed that tumor responses and complete chimerism occur with very low levels of CD34+ cells/kg and that the extent of previous treatment is a critical factor in determining chimerism. A major feature of transplants is the phenotype of the donor stem cell. This phenotype shows dramatic reversible plasticity involving differentiation, adhesion protein expression, and engraftment with cytokine-induced cell-cycle transit. Homing is probably also plastic. Marked fluctuations in engraftment capacity are also seen at different points in marrow circadian rhythm.

Adolescent↗

PubMed2001

Stem cell plasticity in muscle and bone marrow.

Recent discoveries have demonstrated the extraordinary plasticity of tissue-derived stem cells, raising fundamental questions about cell lineage relationships and suggesting the potential for novel cell-based therapies. We have examined this phenomenon in a potential reciprocal relationship between stem cells derived from the skeletal muscle and from the bone marrow. We have discovered that cells derived from the skeletal muscle of adult mice contain a remarkable capacity for hematopoietic differentiation. Cells prepared from muscle by enzymatic digestion and 5 day in vitro culture were harvested and introduced into each of six lethally irradiated recipients together with distinguishable whole bone marrow cells. Six and twelve weeks later, all recipients showed high-level engraftment of muscle-derived cells representing all major adult blood lineages. The mean total contribution of muscle cell progeny to peripheral blood was 56%, indicating that the cultured muscle cells generated approximately 10- to 14-fold more hematopoietic activity than whole bone marrow. Although the identity of the muscle-derived hematopoietic stem cells is still unknown, they may be identical to muscle satellite cells, some of which lack myogenic regulators and could respond to hematopoietic signals. We have also found that stem cells in the bone marrow can contribute to cardiac muscle repair and neovascularization after ischemic injury. We transplanted highly purified bone marrow stem cells into lethally irradiated mice that subsequently were rendered ischemic by coronary artery occlusion and reperfusion. The engrafted stem cells or their progeny differentiated into cardiomyocytes and endothelial cells and contributed to the formation of functional tissue.

Age Factors↗

PubMed2001

Expression of multiple subtypes of muscarinic receptors and cellular distribution in the human heart.

Five isoforms of the muscarinic acetylcholine receptor (mAChR) have been identified by molecular cloning and designated m(1)-m(5), of which four correspond to the functional subtypes M(1), M(2), M(3), and M(4) in primary tissues. The presence of M(5) receptors in tissues remains uncertain. The present study was designed to explore the diversity and cellular distribution of various mAChR subtypes in human hearts. Competition binding of [N-methyl-(3)H]-scopolamine methyl chloride with various mAChR antagonists yielded data consistent with the presence of multiple subtypes (M(1)/M(2)/M(3)/M(5)) of mAChRs in both human atrial (HA) and ventricular (HV) tissues. Expression of mRNAs encoding all five subtypes was readily detected by reverse transcription-polymerase chain reaction in both HA and HV samples. Immunoblotting with subtype-specific antibodies confirmed the presence of M(1), M(2), M(3), and M(5), but not M(4), proteins in membrane preparations from both HA and HV. The protein levels of M(1) and M(2) were comparable between HA and HV. Although the density of M(3) appeared approximately 10-fold higher in HV than HA, that of M(5) was approximately 5 times lower in HV than in HA. Positive immunostaining of single ventricular myocytes by M(1), M(2), M(3), and M(5) antibodies, respectively, was consistently detected. Under confocal microscopy, M(5) showed characteristic localization to the intercalated discs, whereas other subtypes were more evenly distributed throughout the surface membrane. Our results provide the first molecular evidence for the presence of multiple subtypes of mAChR, including endogenous M(5) receptors, in human hearts and suggest that different subtypes have different tissue distributions and cellular localization.

Binding, Competitive↗

PubMed2001

Genetic characterization of highly fluoroquinolone-resistant clinical Escherichia coli strains from China: role of acrR mutations.

The genetic basis for fluoroquinolone resistance was examined in 30 high-level fluoroquinolone-resistant Escherichia coli clinical isolates from Beijing, China. Each strain also demonstrated resistance to a variety of other antibiotics. PCR sequence analysis of the quinolone resistance-determining region of the topoisomerase genes (gyrA/B, parC) revealed three to five mutations known to be associated with fluoroquinolone resistance. Western blot analysis failed to demonstrate overexpression of MarA, and Northern blot analysis did not detect overexpression of soxS RNA in any of the clinical strains. The AcrA protein of the AcrAB multidrug efflux pump was overexpressed in 19 of 30 strains of E. coli tested, and all 19 strains were tolerant to organic solvents. PCR amplification of the complete acrR (regulator/repressor) gene of eight isolates revealed amino acid changes in four isolates, a 9-bp deletion in another, and a 22-bp duplication in a sixth strain. Complementation with a plasmid-borne wild-type acrR gene reduced the level of AcrA in the mutants and partially restored antibiotic susceptibility 1.5- to 6-fold. This study shows that mutations in acrR are an additional genetic basis for fluoroquinolone resistance.

Anti-Infective Agents↗

PubMed2001

Phylogenetic and evolutionary relationships among yellow fever virus isolates in Africa.

Previous studies with a limited number of strains have indicated that there are two genotypes of yellow fever (YF) virus in Africa, one in west Africa and the other in east and central Africa. We have examined the prM/M and a portion of the E protein for a panel of 38 wild strains of YF virus from Africa representing different countries and times of isolation. Examination of the strains revealed a more complex genetic relationship than previously reported. Overall, nucleotide substitutions varied from 0 to 25.8% and amino acid substitutions varied from 0 to 9.1%. Phylogenetic analysis using parsimony and neighbor-joining algorithms identified five distinct genotypes: central/east Africa, east Africa, Angola, west Africa I, and west Africa II. Extensive variation within genotypes was observed. Members of west African genotype II and central/east African genotype differed by 2.8% or less, while west Africa genotype I varied up to 6.8% at the nucleotide level. We speculate that the former two genotypes exist in enzootic transmission cycles, while the latter is genetically more heterogeneous due to regular human epidemics. The nucleotide sequence of the Angola genotype diverged from the others by 15.7 to 23.0% but only 0.4 to 5.6% at the amino acid level, suggesting that this genotype most likely diverged from a progenitor YF virus in east/central Africa many years ago, prior to the separation of the other east/central African strains analyzed in this study, and has evolved independently. These data demonstrate that there are multiple genotypes of YF virus in Africa and suggest independent evolution of YF virus in different areas of Africa.

Africa↗

PubMed2001

Macrophage tropism of human immunodeficiency virus type 1 isolates from brain and lymphoid tissues predicts neurotropism independent of coreceptor specificity.

The viral determinants that underlie human immunodeficiency virus type 1 (HIV-1) neurotropism are unknown, due in part to limited studies on viruses isolated from brain. Previous studies suggest that brain-derived viruses are macrophage tropic (M-tropic) and principally use CCR5 for virus entry. To better understand HIV-1 neurotropism, we isolated primary viruses from autopsy brain, cerebral spinal fluid, blood, spleen, and lymph node samples from AIDS patients with dementia and HIV-1 encephalitis. Isolates were characterized to determine coreceptor usage and replication capacity in peripheral blood mononuclear cells (PBMC), monocyte-derived macrophages (MDM), and microglia. Env V1/V2 and V3 heteroduplex tracking assay and sequence analyses were performed to characterize distinct variants in viral quasispecies. Viruses isolated from brain, which consisted of variants that were distinct from those in lymphoid tissues, used CCR5 (R5), CXCR4 (X4), or both coreceptors (R5X4). Minor usage of CCR2b, CCR3, CCR8, and Apj was also observed. Primary brain and lymphoid isolates that replicated to high levels in MDM showed a similar capacity to replicate in microglia. Six of 11 R5 isolates that replicated efficiently in PBMC could not replicate in MDM or microglia due to a block in virus entry. CD4 overexpression in microglia transduced with retroviral vectors had no effect on the restricted replication of these virus strains. Furthermore, infection of transfected cells expressing different amounts of CD4 or CCR5 with M-tropic and non-M-tropic R5 isolates revealed a similar dependence on CD4 and CCR5 levels for entry, suggesting that the entry block was not due to low levels of either receptor. Studies using TAK-779 and AMD3100 showed that two highly M-tropic isolates entered microglia primarily via CXCR4. These results suggest that HIV-1 tropism for macrophages and microglia is restricted at the entry level by a mechanism independent of coreceptor specificity. These findings provide evidence that M-tropism rather than CCR5 usage predicts HIV-1 neurotropism.

Amino Acid Sequence↗

PubMed2001

Isomerization of a uniquely designed amplicon during herpes simplex virus-mediated replication.

Herpes simplex virus (HSV) type 1 DNA isomerization was studied using a uniquely designed amplicon that mimics the viral genomic structure. The results revealed that amplicon concatemers frequently contain adjacent amplicon units with their segments in opposed orientations. These unusual concatemers were generated through homologous recombination, which does not require HSV DNA as the source of homology.

Animals↗

PubMed2001

Detection of direct binding of human herpesvirus 8-encoded interleukin-6 (vIL-6) to both gp130 and IL-6 receptor (IL-6R) and identification of amino acid residues of vIL-6 important for IL-6R-dependent and -independent signaling.

Human herpesvirus 8 (HHV-8) is associated with Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease; in all of these diseases, interleukin-6 (IL-6) has been implicated as a likely mitogenic and/or angiogenic factor. HHV-8 encodes a homologue of IL-6 (viral IL-6 [vIL-6]) that has been shown to be biologically active in several assays and whose activities mirror those of its mammalian counterparts. Like these proteins, vIL-6 mediates its effects through the gp130 signal transducer, but signaling is not dependent on the structurally related IL-6 receptor (IL-6R; gp80) subunit of the receptor-signal transducer complex. However, as we have shown previously, IL-6R can enhance vIL-6 signal transduction and can enable signaling through a gp130 variant (gp130.PM5) that is itself unable to support vIL-6 activity, indicating that IL-6R can form part of the signaling complex. Also, our analysis of a panel of vIL-6 mutants in transfection experiments in Hep3B cells (that express IL-6R and gp130) showed that most were able to function normally in this system. Here, we have used in vitro vIL-6-receptor binding assays to demonstrate direct binding of vIL-6 to both gp130 and IL-6R and vIL-6-induced gp130-IL-6R complex formation, and we have extended our functional analyses of the vIL-6 variants to identify residues important for IL-6R-independent and IL-6R-dependent signaling through native gp130 and gp130.PM5, respectively. These studies have identified residues in vIL-6 that are important for IL-6R-independent and IL-6R-mediated functional complex formation between vIL-6 and gp130 and that may be involved directly in binding to gp130 and IL-6R.

Antigens, CD↗

PubMed2001

Langat virus M protein is structurally homologous to prM.

Langat (LGT) virus M protein has been generated in a recombinant system. Antiserum raised against the LGT virus M protein neutralizes tick-borne encephalitis serocomplex flaviviruses but not mosquito-borne flaviviruses, indicating that the M protein is exposed on the surface of virions. The antiserum recognizes intracellular LGT virus prM/M and binds to prM and M in Western blots of whole-cell lysates and purified virus, respectively. These data suggest that the prM and M proteins are structurally similar under native conditions and support the hypothesis that the "pr" portion of prM facilitates proper folding of the M protein for expression on the virion surface.

Amino Acid Sequence↗

PubMed2001

Inhibition of glioma cell growth and tumorigenic potential by CCN3 (NOV).

AIMS: To establish whether the ectopic expression of CCN3 (NOV) in glioma cells can interfere with their tumorigenic potential and assess its potential value in molecular medicine. METHODS: Glioma cell lines were used to assess whether differences in the degree of intracellular communication induced by the expression of the gap junction protein connexin 43 (Cx43) is related to the differential expression of CCN3 (NOV). The antiproliferative activity of rat CCN3 (rCCN3; NOV) in glioma cells, has been assessed both in vitro and in vivo with glioma cell lines expressing different amounts of CCN3 (NOV). RESULTS: Upon ectopic expression of Cx43, the growth of C6 glioma cells is decreased. An increase of CCN3 (NOV) expression matches the reduced tumorigenic potential of these transfected cells. The localisation of CCN3 (NOV) is affected by the increased expression of Cx43 in the Cx-13 transfected cells, in which it is detected at areas of cell-cell contact. In a xenograft model, CCN3 (NOV) transfected glioma cells were found to induce tumours to a lesser degree than their parental counterparts, which do not express detectable amounts of CCN3 (NOV). CONCLUSIONS: Previous observations had suggested an inverse relation between CCN3 (NOV) expression in glioma cells and their tumorigenicity. These results establish a direct association between the establishment of functional gap junctional intercellular communication and the expression of rCCN3 (NOV). In addition to a negative effect on murine and human cell growth, CCN3 (NOV) has antiproliferative activity on tumour cells in vivo. Thus, the antiproliferative activity of the CCN3 (NOV) protein might involve reorganisation of cellular contacts that play a crucial role in tumorigenesis. The antiproliferative activity of CCN3 (NOV) established in this work sets the stage for the potential use of CCN proteins in molecular oncology.

Animals↗

PubMed2001

alpha1H T-type Ca2+ channel is the predominant subtype expressed in bovine and rat zona glomerulosa.

The low voltage-activated (T-type) Ca2+ channel has been implicated in the regulation of aldosterone secretion from the adrenal zona glomerulosa by extracellular K+ levels, angiotensin II, and ACTH. However, the identity of the specific subtype mediating this regulation has not been determined. We utilized in situ hybridization to examine the distribution of three newly cloned members of the T-type Ca2+ channel family, alpha1G, alpha1H, and alpha1I, in the rat and bovine adrenal gland. Substantial expression of only the mRNA transcript for the alpha1H-subunit was detected in the zona glomerulosa of both rat and bovine. A much weaker expression signal was detected for the alpha1H transcript in the zona fasciculata of bovine. Whole cell recordings of isolated bovine adrenal zona glomerulosa cells showed the native low voltage-activated current to be inhibited by NiCl2 with an IC50 of 6.4 +/- 0.2 microM. Because the alpha1H subtype exhibits similar NiCl2 sensitivity, we propose that the alpha1H subtype is the predominant T-type Ca2+ channel present in the adrenal zona glomerulosa.

Amino Acid Sequence↗

PubMed2001

Regulation of apolipoprotein secretion by long-chain polyunsaturated fatty acids in newborn swine enterocytes.

Long-chain polyunsaturated fatty acids (LC-PUFA) are important in the development of the immature nervous system, and adding these fatty acids to infant formula has been proposed. To determine the effect of n-3 LC-PUFA on apolipoprotein secretion and lipid synthesis in newborn swine enterocytes, differentiated IPEC-1 cells were incubated for 24 h with docosahexaenoic acid (DHA; 22:6) or eicosapentaenoic acid (EPA; 20:5) complexed with albumin at a fatty acid concentration of 0.8 mM or albumin alone (control) added to the apical medium. Oleic acid (OA; 18:1) was used a control for lipid-labeling studies. Both DHA and EPA reduced apolipoprotein (apo) B secretion by one-half, whereas EPA increased apo A-I secretion. The increased apo A-I secretion occurred primarily in the high-density lipoprotein fraction. These changes in apoprotein secretion were not accompanied by significant changes in synthesis. Modest decreases in apo B mRNA levels were observed for DHA and EPA, whereas there were no changes in apo A-I mRNA abundance. EPA reduced cellular triacylglycerol labeling by one-half, and DHA and EPA decreased cellular phospholipid labeling compared with OA. Labeled triacylglycerol secretion was decreased 75% by EPA, and DHA doubled labeled phospholipid secretion. If present in vivo, these effects should be considered before supplementing infant formula with these fatty acids.

Animals↗