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Biomedical subjects

C Hu

Publications and source records attributed to C Hu.

At least 19 recordsLinked to original sources
PubMed2006

Development changes of cuticular hydrocarbons in Chrysomya rufifacies larvae: potential for determining larval age.

Age determination is the basis of determining the postmortem interval using necrophagous fly larvae. To explore the potential of using cuticular hydrocarbons for determining the ages of fly larvae, changes of cuticular hydrocarbons in developing larvae of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) were investigated using gas chromatography with flame-ionization detection and gas chromatography-mass spectrometry. This study showed that the larvae produced cuticular hydrocarbons typical of insects. Most of the hydrocarbons identified were alkanes with the carbon chain length of 21-31, plus six kinds of alkenes. The hydrocarbon composition of the larvae correlated with age. The statistical results showed that simple peak ratios of n-C29 divided by another eight selected peaks increased significantly with age; their relationships with age could be modelled using exponential or power functions with R(2) close to or > 0.80. These results suggest that cuticular hydrocarbon composition is a useful indicator for determining the age of larval C. rufifacies, especially for post-feeding larvae, which are difficult to differentiate by morphology.

Aging↗
PubMed2006

Peroxisome proliferator-activated receptor (PPAR) delta genetic polymorphism and its association with insulin resistance index and fasting plasma glucose concentrations in Chinese subjects.

AIMS: Previous studies have shown that the peroxisome proliferator-activated receptor delta (PPARD) genetic polymorphism affects cholesterol metabolism in Whites. This association was not observed in a Korean population in a separate study, but this study showed a link between the PPARD polymorphism and body weight and fasting plasma glucose. The purpose of this study was to determine whether polymorphisms of PPARD influence glucose and cholesterol metabolism in Chinese subjects. We investigated the association between the polymorphism (-87T/C) of the human PPARD gene and phenotypes related to body weight, insulin sensitivity, glucose and lipid metabolism in Chinese subjects. METHODS: Unrelated Chinese subjects (n = 663) in Shanghai were studied; 287 had newly diagnosed Type 2 diabetes mellitus and 376 were non-diabetic control subjects over 40 years old. Clinical parameters were collected and genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: In normal glucose tolerant (NGT) subjects, the C allele carriers had higher fasting plasma glucose concentrations (P = 0.0078) and a lower insulin sensitivity index (ISI) (P = 0.0365). The C allele carriers also showed higher concentrations of low-density lipoprotein cholesterol (P = 0.0261) and percentage of body fat (P = 0.0357). There was a trend towards higher visceral adiposity in C allele carriers, but the difference was not significant (P = 0.0830). In diabetes patients, similar results were detected for plasma glucose concentrations (fasting plasma glucose P < 0.0001, 2-h plasma glucose P = 0.0052) and insulin sensitivity (homeostasis model assessment of insulin resistance P = 0.0094; ISI P = 0.0058). CONCLUSION: The PPARD-87T/C polymorphism is associated with higher fasting plasma glucose concentrations in both NGT and diabetic subjects, largely due to impaired insulin sensitivity.

Blood Glucose↗
PubMed2005

Enhanced basal apoptosis in cultured term human cytotrophoblasts is associated with a higher expression and physical interaction of p53 and Bak.

We tested the hypothesis that the expression levels of p53 and the pro-apoptotic mediators from the Bcl-2 family are higher in cytotrophoblasts, when compared to cultures with abundant syncytiotrophoblasts. Cytotrophoblasts isolated from normal term human placentas were cultured in Dulbecco's Modified Eagle medium (DMEM) for 24 h, when the cytotrophoblast phenotype predominates, in DMEM for 72 h, when the syncytiotrophoblast phenotype predominates, or in Ham's-Waymouth medium or DMEM with 1.5% dimethylsulfoxide, each of which maintains the cytotrophoblast phenotype through 72 h of culture. Apoptosis was assessed by detection of cleavage products of poly-ADP-ribose polymerase, by expression of cleaved cytokeratin 18 intermediate filaments, and by assessment of caspase-3 activity. Independent of time in culture, cytotrophoblasts showed higher levels of apoptosis compared to syncytiotrophoblasts. Cytotrophoblasts also expressed a 2-fold higher level of p53, a 2-fold lower level of 60 kDa Mdm-2 protein, a 2-fold higher level of Bak, but no differences in the expression of 90 kDa Mdm-2, Bcl-2, Bcl-X(L), Mcl-1, Bax, Bad, and Bad phosphorylated at the serine(112), serine(136), or serine(155) sites, compared to the syncytiotrophoblasts. Using co-immunoprecipitation, we demonstrated a greater degree of Bak-p53 interaction in cytotrophoblasts than in syncytiotrophoblasts. We also detected Bak-Mcl-1 interaction that was no different between the two phenotypes. Among the proteins studied, enhanced p53 activity, differential Bak expression, and Bak-p53 interactions may contribute to the higher level of constitutive apoptosis in cultures of cytotrophoblasts compared to syncytiotrophoblasts.

Apoptosis↗
PubMed2005

Dramatic development of severe SLE in a patient with an incomplete disease.

This case report describes the previously-unreported clinical course of a patient with a so-called incomplete systemic lupus erythematosus (SLE), i.e. symptoms related to one organ system only, together with the presence of ANA. He had an indolent course initially and developed, 6 months after the first symptoms, a severe disease with rapid appearance of major and unusual manifestations. The possibility of fast progression and a grave course of an incomplete SLE should be kept in mind. This report is meant to heighten awareness of such an atypical presentation so that prompt and aggressive immunosuppressive therapy may be instituted.

Abdomen, Acute↗
PubMed2005

Dandelion (Taraxacum officinale) flower extract suppresses both reactive oxygen species and nitric oxide and prevents lipid oxidation in vitro.

Flavonoids and coumaric acid derivatives were identified from dandelion flower (Taraxacum officinale). Characteristics of chain-breaking antioxidants, such as extended lag phase and reduced propagation rate, were observed in oxidation of linoleic acid emulsion with the addition of dandelion flower extract (DFE). DFE suppressed both superoxide and hydroxyl radical, while the latter was further distinguished by both site-specific and non-specific hydroxyl radical inhibition. DPPH-radical-scavenging activity and a synergistic effect with alpha-tocopherol were attributed to the reducing activity derived from phenolic content of DFE. A significant (p < 0.05) and concentration-dependent, reduced nitric oxide production from acterial-lipopolysaccharide-stimulated mouse macrophage RAW264.7 cells was observed with the addition of DFE. Moreover, peroxyl-radical-induced intracellular oxidation of RAW264.7 cells was inhibited significantly (p < 0.05) by the addition of DFE over a range of concentrations. These results showed that the DFE possessed marked antioxidant activity in both biological and chemical models. Furthermore, the efficacy of DFE in inhibiting both reactive oxygen species and nitric oxide were attributed to its phenolic content.

Animals↗
PubMed2005

Chondroprotective activity of N-acetylglucosamine in rabbits with experimental osteoarthritis.

OBJECTIVE: To examine the therapeutic efficacy of N-acetylglucosamine (GlcNAc) in rabbits with experimental osteoarthritis (OA). METHODS: Experimental OA was induced in rabbits by anterior cruciate ligament transection (ACLT). In the first study, rabbits (six in each group) received intramuscular injections of GlcNAc or normal saline three times a week starting 1 week postoperatively. In the second study, rabbits (eight in each group) were injected intra-articularly with GlcNAc (either once or twice a week) or normal saline. In the third study, rabbits (seven in each group) were injected intra-articularly twice a week with either GlcNAc, hyaluronan, or normal saline. Animals were killed 8 weeks after ACLT for macroscopic and histological assessment of the knee joints. RESULTS: Intramuscular administration of GlcNAc in rabbits with experimental knee OA did not show chondroprotective effects but showed mild anti-inflammatory activity. In contrast, intra-articular administration of GlcNAc twice a week reduced cartilage degradation. Additionally, intra-articular GlcNAc also suppressed synovitis. Once a week intra-articular injections of GlcNAc did not demonstrate therapeutic efficacy. The chondroprotective efficacy of GlcNAc was better than that of viscosupplementation treatment with hyaluronan. CONCLUSION: Intra-articular GlcNAc has chondroprotective and anti-inflammatory activity in experimental OA.

Acetylglucosamine↗
PubMed2005

Inhibition of Measles virus multiplication in cell culture by RNA interference.

Measles takes a toll of one million people a year worldwide, especially in developing countries. As the so far applied vaccines were not able to control this disease, novel approaches to this problem are needed. In this study, we investigated the possibility of inhibition of Measles virus (MV) infection through RNA interference (RNAi), namely the interference with the second but main receptor of MV, signaling lymphocyte activation molecule (SLAM), in an Epstein-Barr virus (EBV)-transformed marmoset B cell line B95-8. Three potential target sequences in the SLAM gene were chosen and cloned into the pSilencer 3.0-H1 vector. The vector constructs were used for transfection of B95-8 cells in which SLAM was then detected by flow cytometry, Western blot analysis and RT-PCR both at transcription and expression levels. One of the vector constructs was found to block effectively the SLAM expression as well as MV infection. These results suggest that RNAi could silence SLAM expression and inhibit the MV infection of host cells.

Amino Acid Sequence↗
PubMed2004

Bioremediation of methyl tertiary-butyl ether (MTBE) by an innovative biofilter.

Methyl tertiary-butyl ether (MTBE) is a synthetic chemical used in unleaded gasoline as an additive to reduce levels of ozone and carbon monoxide from auto exhaust. Due to its chemical and recalcitrant properties, MTBE has caused groundwater contamination worldwide. A laboratory-scale biofilter made of a natural fiber (kenaf) mat and inoculated with MTBE-degrading microorganisms, was evaluated for MTBE removal efficiency. Operational parameters of oxygen flow rate, hydraulic retention time (HRT), yeast extract and initial MTBE concentration were varied and MTBE removal efficiencies determined. Four kinetic models were evaluated to describe the MTBE removal in the reactor. Formaldehyde and tertiary butyl alcohol (the most two reported MTBE biodegradation byproducts) were not found in the effluent; instead, carbon dioxide was monitored as the end product based on the results of a metabolic mass balance evaluation. Toxicity of treated effluent was evaluated by employing the Microtox acute toxicity test and comparing that to the influent.

Biodegradation, Environmental↗
PubMed2003

Structure and expression of spermidine synthase genes in apple: two cDNAs are spatially and developmentally regulated through alternative splicing.

Three cDNAs (MdSPDS1, 2a and 2b) encoding spermidine synthase (SPDS), a key enzyme in the polyamine biosynthesis, have been cloned from apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. The deduced amino acid sequences of their protein products share 76-83% identity with SPDSs of other higher plants. A comparison of the sequences of the three cDNAs and of the two corresponding genomic DNA fragments (SPDS1 and SPDS2) indicated that MdSPDS1 was transcribed from the SPDS1 sequence, whereas MdSPDS2a and MdSPDS2b were both derived from SPDS2 by alternative splicing. To learn more about the physiological roles of MdSPDS1, MdSPDS2a and MdSPDS2b, Northern analyses were carried out, together with measurements of polyamine content. Levels of both MdSPDS1 and MdSPD2a were higher in young leaves than in mature leaves and shoots. In fruits, mRNA levels were nearly as high as in young leaves and remained high during fruit development. By RT-PCR, MdSPDS2b transcripts were detected in mature leaves and shoots, but not in young leaves and fruits. These results indicate that MdSPDS2a and MdSPDS2b are differentially regulated in a tissue- and developmentally specific manner. The content of free polyamines in mesocarp tissues was measured at five stages of fruit development. At all stages, spermidine (Spd) was the predominant form of polyamine. The level of Spd was high at the early growth stage and declined to about 90% during later developmental stages. The possible regulation of SPDS expression during apple fruit development is discussed.

Alternative Splicing↗
PubMed2001

Twinned dichlorobis(2,6-dichloropyrazine-N(4))zinc(II).

For crystals of the title compound, [ZnCl(2)(C(4)H(2)Cl(2)N(2))(2)], metric considerations suggest a monoclinic unit cell. However, the symmetry of the diffraction pattern shows the crystals to be triclinic, with very similar lattice constants a and b, and alpha and beta. All crystals examined were twinned. The discrepancy between the reliability indices for merging in the monoclinic lattice metric symmetry and the triclinic crystal symmetry constitutes an indicator for the volume ratio between the components. The asymmetric unit contains three independent molecules. At the molecular level, the compound shows a distorted tetrahedral coordination around one Zn atom.

Crystallography, X-Ray↗
PubMed2001

A three-dimensional inorganic/organic hybrid material, [Ni(4,4'-bipy)3-(H2O)2V4O12]*2.5H2O.

The title compound, poly[[[diaqua(mu-4,4'-bipyridyl)dinickel(II)]-bis(mu-4,4'-bipyridyl)-di-mu-hexaoxodivanadate(2-)] 2.5-hydrate], [Ni2(V2O6)2(C10H8N2)3(H2O)2]*2.5H2O, has been prepared hydrothermally and characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffraction. The structure consists of [V2O6], [Ni(4,4'-bipy)4O2] and [Ni(H2O)2(4,4'-bipy)2O2] polyhedra, and water of crystallization. The Ni atoms and one bipyridyl group lie on centres of symmetry.

Journal Article↗
PubMed2001

The tRNA-binding moiety in GCN2 contains a dimerization domain that interacts with the kinase domain and is required for tRNA binding and kinase activation.

GCN2 stimulates translation of GCN4 mRNA in amino acid-starved cells by phosphorylating translation initiation factor 2. GCN2 is activated by binding of uncharged tRNA to a domain related to histidyl-tRNA synthetase (HisRS). The HisRS-like region contains two dimerization domains (HisRS-N and HisRS-C) required for GCN2 function in vivo but dispensable for dimerization by full-length GCN2. Residues corresponding to amino acids at the dimer interface of Escherichia coli HisRS were required for dimerization of recombinant HisRS-N and for tRNA binding by full-length GCN2, suggesting that HisRS-N dimerization promotes tRNA binding and kinase activation. HisRS-N also interacted with the protein kinase (PK) domain, and a deletion impairing this interaction destroyed GCN2 function without reducing tRNA binding; thus, HisRS-N-PK interaction appears to stimulate PK function. The C-terminal domain of GCN2 (C-term) interacted with the PK domain in a manner disrupted by an activating PK mutation (E803V). These results suggest that the C-term is an autoinhibitory domain, counteracted by tRNA binding. We conclude that multiple domain interactions, positive and negative, mediate the activation of GCN2 by uncharged tRNA.

Allosteric Regulation↗
PubMed2001

[Case control study of the relationship between type A character and type II diabetes mellitus].

OBJECTIVE: To explore the relationship between type A character and type II diabetes mellitus. METHODS: A frequency matched case control study based on hospital involving 185 newly diagnosed type II diabetics, 201 control cases without type II diabetes mellitus, and 197 healthy people was carried out in Xuzhou City, Jiangsu Province, using type A character questionnaire and unified questionnaire. Nonconditional univariate and multivariate logistic regression analyses were used with the software Statistical Package for the Social Sciences for Windows release 8.0. RESULTS: The score of TH (time hurry), CH (competition and hostility), and the sum of TH and CH of the type II diabetes mellitus cases were significantly higher than those of the control cases (P < 0.01). Compared with B-type character, type A character (OR = 2.59, 95% CI: 1.62 approximately 4.13) was more significantly associated with type II diabetes mellitus after adjustment of occupation, education, family history of diabetes mellitus, waist to hip ratio (WHR), smoking, drinking, dietary factors, leisure time physical activity and hypertension. CONCLUSION: Type A character may be one of the risk factors of type II diabetes mellitus.

Case-Control Studies↗
PubMed2001

Cloning, sequencing, and characterization of CYP1A1 cDNA from leaping mullet (Liza Saliens) liver and implications for the potential functions of its conserved amino acids.

A 2,037 bp CYP1A1 cDNA (GenBank AF072899) was cloned through screening of a lambdaZipLox cDNA library constructed from the liver of a leaping mullet (Liza saliens) fish captured from Izmir Bay on the Aegean coast of Turkey using rainbow trout CYP1A1 cDNA as a probe. This clone has a 130 bp 5'-flanking region, a 1,563 bp open reading frame (ORF) encoding a 521-amino acid protein (58,972 Da), and a 344 bp 3'-untranslated region without a poly (A) tail. Alignment of the deduced amino acids of CYP1A1 cDNAs showed 58% and 69-96% identities with human and 12 other fish species, respectively. Southern blot analysis suggested that this CYP1A1 cDNA was from a single-copy gene. Based on the comparison with CYP1A1 genes reported for fish and mammals, the leaping mullet CYP1A1 gene is probably split into 7 exons. The intron insertion sites were predicted. Alignment of the CYP1A1 cDNA encoded amino acids from 13 fish and 7 mammalian species disclosed differences in highly conserved amino acids between aquatic and land vertebrates. The possible associated secondary structure; conserved motifs and substrate-binding sites were discussed. The phylogenetic relationships of CYP1A1s among 13 fish species were analyzed by a distance method.

Amino Acid Sequence↗
PubMed2001

Antioxidant activity of a Rhus verniciflua Stokes ethanol extract.

A fractionated ethanol extract derived from Rhus Verniciflua Stokes (RVS) was assessed in both organic and aqueous media for the purpose of characterizing the mechanisms of antioxidant activity. RVS, an indigenous plant to Korea, was initially extracted with ethanol and characterized to contain a 90 KDa-ABTS reactive protein possessing 0.662 ng/mg copper. This characterization suggested that a primary component of RVS was Laccase, an oxidase enzyme complex. RVS exhibited a significant (P < 0.01) concentration-dependent inhibition of linoleic acid oxidation in an emulsion system up to 48 hours of incubation. Free radical scavenging activity of both a stable radical (e.g DPPH) and hydroxyl (e.g. *OH) radical followed a concentration-dependent pattern in different model systems. Using a liposome model with peroxyl radicals generated by AAPH, a significant extension of both the lag phase and a reduction of peak propagation of peroxyl radicals by RVS over a concentration range of 1 to 10 microg/ml was observed. RVS ethanol extract was also found to protect human low-density lipoprotein (LDL) from oxidative modification, mediated by cupric ion at 37 degrees C. Finally, RVS was found to be effective at protecting against plasmid DNA strand breakage induced by peroxyl free radicals in an aqueous medium. Our findings show that the ethanol fraction derived from RVS contained significant antioxidant activity in both polar and non-polar mediums.

Antioxidants↗
PubMed2001

Evaluation of antioxidant activity of epigallocatechin gallate in biphasic model systems in vitro.

The antioxidant activity of epigallocatechin gallate (EGCG) was studied in different in vitro model systems, which enabled evaluation of both chemical and physical factors involved in assessing the role of EGCG in oxidative reactions. EGCG suppressed the initiation rate and prolonged the lag phase duration of peroxyl radical-induced oxidation in a phospholipid liposome model to a greater extent (p < 0.01) compared to both Trolox and alpha-tocopherol. Effectiveness of these antioxidants to prolong the peroxyl radical-induced lag phase was inversely related to lipophilic character. EGCG also protected against both peroxyl radical and hydroxyl radical-induced supercoiled DNA nicking. The rate constant describing EGCG reaction against hydroxyl radical was 4.22+/-0.07 x 10(10) M(-1) x sec(-1), which was comparable to those of Trolox and alpha-tocopherol, respectively. EGCG exhibited a synergistic effect with alpha-tocopherol in scavenging 1,1-diphenyl-2-picylhydrazyl (DPPH) radical, thus displaying a direct free radical scavenging capacity. In vitro Cu2+-induced-human LDL oxidation was accelerated in the presence of EGCG and attributed to the conversion of Cu2+ to Cu+. We conclude that the particularly effective antioxidant properties of EGCG noted in both chemical and biological biphasic systems were related to a unique hydrophilic and lipophilic balance which enabled effective free radical scavenging. The same chemical-physical properties of EGCG also enabled prooxidant activity, only when in contact with unbound transition metal ions in a multiphasic system.

2,2'-Dipyridyl↗
PubMed2001

Purification and characterization of the membrane-bound complex of an ABC transporter, the histidine permease.

The bacterial histidine permease, an ABC transporter, from Salmonella typhimurium is composed of a membrane-bound complex, HisQMP2, comprising two hydrophobic subunits (HisQ and HisM), two copies of an ATP-hydrolyzing subunit, HisP, and a soluble receptor, HisJ. We describe the purification and characterization of HisQMP2 using a 6-histidines extension at the carboxy terminus of HisP [HisQMP2(his6)]. The purification is rapid and effective, giving a seven-fold purification with a yield of 85 and 98% purity. Two procedures are described differing in the detergent used (decanoylsucrose and octylglucoside, respectively) and in the presence of phospholipid. HisQMP2(his6) has ATPase and transport activities upon reconstitution into proteoliposomes (PLS). HisQMP2(his6) has a low level ATPase activity (intrinsic activity), which is stimulated to a different extent by the receptor--liganded and unliganded. Its pH optimum is 7.8-8.0, it requires a cation for activity and it displays cooperativity for ATP. The effect of various ATP analogs was analyzed. Determination of the molecular size of HisQMP2(his6) indicates that it is a monomer. The permeability properties of two kinds of reconstituted PLS preparations are described.

ATP-Binding Cassette Transporters↗