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Biomedical subjects

Hui Liu

Publications and source records attributed to Hui Liu.

At least 199 records · Page 11Linked to original sources
PubMed2003

[Early-stage conservative removal of scars and delayed skin grafting for severe burns in the neck: report of 13 cases].

OBJECTIVE: To optimize the treatments for severe burns in the neck to prevent the hypertrophy, contraction and deformation of the scars and avoid repeated surgical repair. METHODS: At the early stage of severe neck burns, conservative removal of the scabs was adopted with a small portion of the necrotic tissues preserved. Wound addressing was performed with anti-infection measures supplemented with the application of agents for dissolving the scars, promoting the epithelial growth and preventing local inflammation. Wound repair with large pieces of autologous skin grafts of medium or full thickness was performed with reasonable delay, after which the neck was fixed with thermoplastic splints. RESULTS: The wounds of 13 patients in this survey healed smoothly within 3 weeks, and no obvious hypertrophy, contracture or deformation of the scars was observed. The patients complained no restrained movement of the neck, and adhesion did not occur in the chin, neck or the chest. CONCLUSION: The method described above may help promote the healing of the neck burns and reduce the incidences of hypertrophy, contracture and deformation of the scars, which avoids further operations for the repair.

Adolescent↗
PubMed2003

[Analysis of the genomic organization of a novel scorpion toxin BmTXK beta].

Scorpion venoms contain different types of low molecular mass toxic peptides acting on ion channels. Many cDNAs and genomic genes encoding these toxins have been isolated and sequenced while the mechanisms of expression and regulation of scorpion toxins is not well studied yet. BmTXK beta, one of the four putative long-chain potassium channel toxins, is isolated from the cDNA library of the venom gland of Chinese scorpion BmK (Buthus martensii Karsch). It has an 886 bp intron located in the mature peptide while other scorpion toxins' introns are located in the signal peptide. The special genomic organization of BmTXK beta makes it a good object to study the mechanism of expression and regulation of scorpion toxins. With primers designed according to the already known sequence of BmTXK beta, its 5' and 3' flanking regions are cloned by the Vecttorette II Staorette Pack method and sequenced. Analysis of the sequence shows that another intron longer than 997 bp is located in the signal peptide region of BmTXK beta, which makes BmTXK beta different from all the other scorpion toxins that have no intron or only one intron in the signal peptide. The special genomic organization of BmTXK beta indicates that BmTXK beta is a new membership of long-chain potassium channel toxin.

Amino Acid Sequence↗
PubMed2003

Inhibitory effects of recombinant neurotoxin BmK IM on seizures induced by pentylenetetrazol in Rats.

OBJECTIVE: To elucidate the inhibitory effects of recombinant Chinese scorpion neurotoxin BmK IM on seizures induced by pentylenetetrazol (PTZ) and the possible mechanism. METHODS: After purifying recombinant BmK IM from an E. coli cell line, its toxicity (both LD50 and minimum lethal dose) on rats was determined. BmK IM was then microinjected into the CA3 region of the right hippocampus and its ability to inhibit the effects of an intraperitoneal injection of PTZ was assessed. The effects of BmK IM on the electrophysiological properties of isolated CA3 pyramidal neurons were then studied using whole-cell patch clamp techniques. RESULTS: BmK IM can significantly prolong the latent period of epileptic seizures, decrease the degree of seizures, and decrease the frequency of epileptiform discharges induced by PTZ. At the same time, 24h after injection of BmK IM into the hippocampal tissue, BmK IM significantly reduces the concentration of the neurotransmitter glutamate and alleviates PTZ-induced lesions in the hippocampus. Whole-cell patch clamp recordings indicate that BmK IM inhibits INa of rat hippocampal neurons in a dose-dependent manner. BmK IM significantly shifts the activation curve of INa in a positive direction, indicating that BmK IM enhances the threshold potential of INa. CONCLUSIONS: BmK IM has significant anti-epileptic properties, and may prove useful as a drug in the therapy of epilepsy. The inhibitory effects of BmK IM on seizures caused by pentylenetetrazol might depend on reductions in the release of presynaptic glutamate via the blocking of Na+ channels.

Animals↗
PubMed2003

[Genetic diversity examination of murine H2Eb by PCR-SSP].

To explore the diversity of genetic background in Kunming (KM) mice, technique of Polymerase Chain Reaction-Sequence Specific Primer (PCR-SSP) was employed to determine the alleles of the 2nd exon on H2Eb in 60 mice. Seventy-eight positive PCR results have been obtained,that is, 65% of alleles were determined and 43.3% of these mice were identical on this locus in genotype. This study,to some extent, revealed the genetic diversity in KM mice.

English Abstract↗
PubMed2002

Genetic variation in the 22q11 locus and susceptibility to schizophrenia.

An increased prevalence of microdeletions at the 22q11 locus has been reported in samples of patients with schizophrenia. 22q11 microdeletions represent the highest known genetic risk factor for the development of schizophrenia, second only to that of the monozygotic cotwin of an affected individual or the offspring of two schizophrenic parents. It is therefore clear that a schizophrenia susceptibility locus maps to chromosome 22q11. In light of evidence for suggestive linkage for schizophrenia in this region, we hypothesized that, whereas deletions of chromosome 22q11 may account for only a small proportion of schizophrenia cases in the general population (up to approximately 2%), nondeletion variants of individual genes within the 22q11 region may make a larger contribution to susceptibility to schizophrenia in the wider population. By studying a dense collection of markers (average one single nucleotide polymorphism20 kb over 1.5 Mb) in the vicinity of the 22q11 locus, in both family- and population-based samples, we present here results consistent with this assumption. Moreover, our results are consistent with contribution from more than one gene to the strikingly increased disease risk associated with this locus. Finer-scale haplotype mapping has identified two subregions within the 1.5-Mb locus that are likely to harbor candidate schizophrenia susceptibility genes.

Amino Acid Sequence↗
PubMed2002

A one-pot synthesis of beta-C-glucopyranosides from exo-glucal, p-tolylsulfenyl chloride, an alpha-methoxyalkene, and an external nucleophile.

[formula: see text] beta-C-Glycosides were synthesized in one-pot experiments using the following sequence of four reactions: (i) addition of p-TolSCl to an alpha-methoxyalkene, (ii) generation of the episulfonium ion from a beta-(arylsulfanyl)alkyl chloride, (iii) reaction of the episulfonium intermediate with benzylated exo-D-glucal to form a cyclic five-membered sulfonium salt, and (iv) quenching of the sulfonium salt with the external nucleophile: H2O, CH3OH, or NaCNBH3.

Calcium Gluconate↗
PubMed2002

A dimeric RNA quadruplex architecture comprised of two G:G(:A):G:G(:A) hexads, G:G:G:G tetrads and UUUU loops.

Using CD and NMR, we determined the structure of an RNA oligomer, r(GGAGGUUUUGGAGG) (R14), comprising two GGAGG segments joined by a UUUU segment. A modified quadruplex structure was observed for r(GGAGGUUUUGGAGG) in solution even in the absence of K(+). An unusually stable dimeric RNA quadruplex architecture formed from two strands of r(GGAGGUUUUGGAGG) at low K(+) concentration is reported here. In each strand of r(GGAGGUUUUGGAGG), two sets of successive turns in the GGAGG segments and turns at both ends of the UUUU loops drive four G-G steps to align in a parallel manner, a core with two stacked G-tetrads being formed. Two adenine bases bind to two edges of one G:G:G:G tetrad through the sheared G:A mismatch augmenting the tetrad into a G:G(:A):G:G(:A) hexad. Thus, one molecule of r(GGAGGUUUUGGAGG) folds into a modified quadruplex comprising a G:G:G:G tetrad, a UUUU double-chain reversal loop and a G:G(:A):G:G(:A) hexad. Two such molecules further associate by stacking through the dimeric hexad-hexad interface with a rotational symmetry. The ribose rings of most nucleotides take S (close to C2'-endo) puckering, which is unusual for an RNA. K(+) can increase the stability of this quadruplex structure; the number of bound K(+) was estimated from the results of the titration experiment. Besides G:G and G:A mismatches, a network of hydrogen bonds including O4'-NH(2) and C-H..O hydrogen bonds, and the extensive base stacking contribute to the high thermodynamic stability of R14. Our results could provide the stereochemical and thermodynamic basis for elucidating the biological role of the GGAGG-containing RNA segments abundantly existing in various RNAs. Relevance to quadruplex-mediated mRNA-FMRP binding and HIV-1 genome RNA dimerization is discussed.

Cations, Monovalent↗
PubMed2002

One-pot synthesis of C-glycosylic compounds (C-glycosides) from D-glucal, p-tolylsulfenyl chloride and aromatic/heteroaromatic compounds in the presence of Lewis acids.

In the presence of Zn(CN)(2), benzylated 2-thio-2-S-(p-tolyl)pyranosyl chlorides (2) generated in situ from tri-O-benzyl-D-glucal and p-TolSCl, smoothly react with thiophene, 2-methylthiophene, furan, 2-methylfuran, and N-methylpyrrole to give heteroaryl 2-thio-2-S-(p-tolyl)-C-beta-D-glucopyranosylic compounds (C-glycosides) in good yields. Upon treatment with SnCl(4), the reaction of chlorides 2 with thiophene or 1,4-dimethoxybenzene provides the corresponding benzylated C-beta-D-glucofuranosylic derivatives. Under the same conditions, the use of 2-methylthiophene, furan, 2-methylfuran, or N-methylpyrrole yields (2S,3R,4R,5S)-1,3,4-tribenzyloxy-6,6-diheteroaryl-5-(p-tolylthio)-2-hexanoles. Treatment of 2 and mesitylene with AgBF(4) yielded 1,6-anhydro-3,4-di-O-benzyl-2-thio-2-S-(p-tolyl)-beta-D-glucose.

Benzyl Compounds↗
PubMed2002

Multiple dendritic catalysts for asymmetric transfer hydrogenation.

The first and second generation multiple dendritic ligands based on chiral diamine were synthesized in a convergent approach and were well-characterized by NMR and MS techniques. Their ruthenium complexes prepared in situ had good solubility in the reaction medium (azeotrope of formic acid and triethylamine) and demonstrated high catalytic activity and enantioselectivity comparable to monomeric catalysts in the asymmetric transfer hydrogenation of ketones and imines. Quantitative yields and for some cases a slightly higher enantioselectivity (up to 98.7% ee) were obtained in the dendritic catalysis. Considering the high local catalyst concentrations at the periphery, diones were tested for the possible synergic reactivity between catalytic units at the surface, while no apparent differences were noted.

Journal Article↗
PubMed2002

Functional replacement of the tobacco rattle virus cysteine-rich protein by pathogenicity proteins from unrelated plant viruses.

Mutation of the 16K gene encoded by RNA1 of Tobacco rattle virus (TRV) greatly reduced the levels of viral RNA that accumulated in both infected protoplasts and plants, showing that the 16K cysteine-rich protein (CRP) is required for efficient multiplication of TRV. Overexpression of the 16K protein, either from an additional copy of the gene carried on TRV RNA2 or from a PVX vector, led to an increase in the severity of disease symptoms, suggesting that the protein has a role in the pathogenicity of the virus. Mutation of the 16K gene could be overcome by expression from RNA2 of the Cucumber mosaic virus 2b gene, the Soil-borne wheat mosaic virus 19K gene, or the Barley stripe mosaic virus gammab gene, indicating that the proteins encoded by these diverse genes may have similar functions. One known function of the CMV 2b gene is as a suppressor of posttranscriptional gene silencing, suggesting that the TRV 16K protein may also possess this activity.

Cysteine↗
PubMed2002

[Clinical value of spiral CT in the surgical treatment of severe acute pancreatitis].

OBJECTIVE: To evaluate the clinical value of spiral CT in the surgical treatment of severe acute pancreatitis (SAP). METHODS: The morphological changes in the spiral CT images of 82 SAP patients were contrasted with the therapeutic methods and the curative effects. RESULTS: The operation for obstructive biliogenic pancreatitis, invasive parapancreas vessels forming angioma, piece and segmental necrosis in the body and tail of the pancreas, the enlargement of pancreas cyst during the treatment, and parapancreas abscess diagnosed by the spiral CT images had a significant curative effect compared with the non-operation treatment (P < 0.05). The satisfactory effect could be gained if a conservative treatment was performed first, and then the delayed operative treatment was carried out according to the etiologic and clinical data for the SAP patients with extensive phlegmona, necrosis in the head of the pancreas, severe parapancreas cyst, and a large amount of ascite. CONCLUSION: Spiral CT can supply the grounds for choosing surgical methods and the surgical opportunity in the treatment of SAP patients.

Acute Disease↗
PubMed2002

[CT in the therapeutic evaluation of rare primary hepatic malignant tumors].

OBJECTIVE: To discuss the significance of CT in the therapeutic evaluation of rare primary hepatic carcinoma. METHODS: The CT images and surgical data of 15 cases of rare primary hepatic malignant tumors were retrospectively analyzed. The correlative relationship between the CT images of common plus enhanced scan and the surgical operative difficulties was also analyzed. RESULTS: If CT images showed that huge lesions existed, severe lobles were involved, capsules were incomplete, the main branch of the portal venous system was involved, and the external structure of the liver was invaded before the operation, the operation might be more difficult, and complications and death might happen. CONCLUSION: CT images will directly indicate the difficulty of operation for rare primary hepatic malignant tumors before the operation, and an objective evaluation on the therapeutic method and operative effect can be made by CT examination.

Adolescent↗
PubMed2002

A highly enantioselective hetero-Diels-Alder reaction of aldehydes with Danishefsky's diene catalyzed by chiral titanium(IV) 5,5',6,6',7,7',8,8'-octahydro-1,1'-bi-2-naphthol complexes.

The catalytic effect of chiral Lewis acids on the hetero-Diels-Alder reaction between aldehydes and Danishefsky's diene (1) has been investigated. A variety of combinations of different ligands and Lewis acids have been examined as catalysts for the hetero-Diels-Alder reaction between benzaldehyde and 1, and it has been found that the readily accessible Ti(IV)-H(8)-BINOL (TiHBOL) complex is a very effective catalyst for the reaction, leading to products with very high enantioselectivity (up to 99% ee) and yield (92%). The hetero-Diels-Alder reaction of other aldehydes with 1 under the catalysis of TiHBOL is a general reaction which proceeds well with very high enantioselectivity and isolated yield for various aldehydes at 0 degrees C to room temperature. Based on the experimental results, the proposed mechanism of the hetero-Diels-Alder reaction and the dihedral angle effects of ligands are discussed.

Journal Article↗
PubMed2002

Genetic variation at the 22q11 PRODH2/DGCR6 locus presents an unusual pattern and increases susceptibility to schizophrenia.

The location of a schizophrenia susceptibility locus at chromosome 22q11 has been suggested by genome-wide linkage studies. Additional support was provided by the observation of a higher-than-expected frequency of 22q11 microdeletions in patients with schizophrenia and the demonstration that approximately 20-30% of individuals with 22q11 microdeletions develop schizophrenia or schizoaffective disorder in adolescence and adulthood. Analysis of the extent of these microdeletions by using polymorphic markers afforded further refinement of this locus to a region of approximately 1.5 Mb. Recently, a high rate of 22q11 microdeletions was also reported for a cohort of 47 patients with Childhood Onset Schizophrenia, a rare and severe form of schizophrenia with onset by age 13. It is therefore likely that this 1.5-Mb region contains one or more genes that predispose to schizophrenia. In three independent samples, we provide evidence for a contribution of the PRODH2/DGCR6 locus in 22q11-associated schizophrenia. We also uncover an unusual pattern of PRODH2 gene variation that mimics the sequence of a linked pseudogene. Several of the pseudogene-like variants we identified result in missense changes at conserved residues and may prevent synthesis of a fully functional enzyme. Our results have implications for understanding the genetic basis of the 22q11-associated psychiatric phenotypes and provide further insights into the genomic instability of this region.

Africa↗
PubMed2002

High prevalence of HIV-1 and hepatitis C virus coinfection among injection drug users in the southeastern region of Yunnan, China.

The southeastern region of Yunnan province is a key site for drug trafficking and HIV-1 infection spread from the west of Yunnan and Laos to southeastern China. To investigate the prevalence of HIV-1 infection and hepatitis C virus (HCV) coinfection among injection drug users (IDUs) in southeastern Yunnan, three cohorts of 285 addicts, including 242 IDUs and 43 oral drug users, living in the cities of Gejiu and Kaiyuan and the county of Yanshan were studied. HIV-1 and HCV infections were detected by enzyme-linked immunosorbent assay and/or polymerase chain reaction. Data on the age, sex, risk behavior, drug use history, employment, ethnic background, and marriage status were obtained by interview. The overall prevalence of HIV-1 infection was 71.9%. The rate of HCV coinfection among 138 HIV-1-infected IDUs was 99.3%. Most HIV-infected IDUs were 20 to 35 years old (86.7%) and were ethnic Han (75.9%), suggesting that the epidemic in Yunnan is no longer confined to non-Han ethnic minorities. HIV prevalence in female IDUs (81.2%) was significantly higher than in male IDUs (68.2%) ( p <.05). The prevalence of HIV infection reached 68.4% after 1 year of injection drug use. Needle/syringe sharing is the major high risk factor for the spread of HIV-1 and HCV infections. Large-scale educational campaigns are urgently needed to reduce the spread of HIV and HCV infection in these regions.

Adolescent↗
PubMed2002

Halide-templated assembly of polynuclear lanthanide-hydroxo complexes.

A series of pentadecanuclear lanthanide-hydroxo complexes possessing a common core of the formula [Ln(15)(mu(3)-OH)(20)(mu(5)-X)](24+)(1, Ln = Eu, X = Cl(-); 2, Ln = Nd, X = Cl(-); 3, Ln = Gd, X = Cl(-); 4, Ln = Pr, X = Br(-); 5, Ln = Eu, X = Br(-)) were prepared by L-tyrosine-controlled hydrolysis of corresponding lanthanide perchlorates in the presence of added Cl(-) or Br(-). The cationic cluster core comprises five vertex-sharing cubane-like [Ln(4)(mu(3)-OH)(4)](8+) units centered on the halide template. In the case of templating I(-), dodecanuclear complexes were isolated instead. The core component, [Ln(12)(mu(3)-OH)(16)(I)(2)](18+) (6, Ln = Dy; 7, Ln = Er), consists of four vertex-sharing cubane-like [Ln(4)(mu(3)-OH)(4)](8+) units and exists as a square-shaped cyclic structure with one I(-) located on each side of the square plane. An analogous hydrolytic reaction involving Er(NO(3))(3), L-tyrosine, and NaOH affords the known hexanuclear complex [Er(6)(mu(6)-O)(mu(3)-OH)(8)(NO(3))(6)(H(2)O)(12)](NO(3))(2) whose core component is a face-capped octahedral [Er(6)(mu(6)-O)(mu(3)-OH)(8)](8+) cluster with an interstitial mu(6)-oxo group (Wang, R.; Carducci, M. D.; Zheng, Z. Inorg. Chem. 2000, 39, 1836-1837.). The efficient self-assembly of halide-encapsulating multicubane complexes (1-7) and the inability to produce an analogous nitrate-containing complex demonstrate the superior templating roles played by the halide ion(s). Further credence for the halide template effects was provided by the isolation of the cationic pentadecanuclear complex 3 as the sole product when tyrosine-supported hydrolysis of Gd(NO(3))(3) was carried out in the presence of competitive Cl(-). Magnetic moments of complexes 1-7 measured at room temperature by using Evans' method are in excellent agreement with those calculated by the Van Vleck equation, assuming magnetically noninteractive lanthanide ions.

Bromides↗
PubMed2002

Point mutants of EHEC intimin that diminish Tir recognition and actin pedestal formation highlight a putative Tir binding pocket.

Attachment to host cells by enterohaemorrhagic Escherichia coli (EHEC) is associated with the formation of a highly organized cytoskeletal structure containing filamentous actin, termed an attaching and effacing (AE) lesion. Intimin, an outer membrane protein of EHEC, is required for the formation of AE lesions, as is Tir, a bacterial protein that is translocated into the host cell to function as a receptor for intimin. We established a yeast two-hybrid assay for intimin-Tir interaction and, after random mutagenesis, isolated 24 point mutants in intimin, which disrupted Tir recognition in this system. Analysis of 11 point mutants revealed a correlation between recognition of recombinant Tir and the ability to trigger AE lesions. Many of the mutations fell within a 50-residue region near the C-terminus of intimin. Alanine-scanning mutagenesis of this region revealed four residues (Ser890, Thr909, Asn916 and Asn927) that are critical for Tir recognition. Mapping the sequences of EHEC intimin and Tir onto the crystal structure of the intimin-Tir complex of enteropathogenic E. coli predicts that each of these four intimin residues lies at the intimin-Tir interface and contributes to a pocket that interacts with Ile298 of EHEC Tir. Thus, this genetic approach to intimin function both identified residues critical for Tir binding and demonstrated a correlation between the ability to bind Tir and the ability to trigger actin focusing.

Actins↗