Biomedical subjects

Hui Zhou

Publications and source records attributed to Hui Zhou.

At least 55 records · Page 3Linked to original sources

PubMed2005

Distinct domains of Bcl-XL are involved in Bax and Bad antagonism and in apoptosis inhibition.

Pro-survival factor Bcl-X(L) can antagonize the pro-apoptotic functions of Bax and Bad via two distinct mechanisms. It can block Bax-mediated cell death by preventing Bax translocation from the cytosol to mitochondria. On the other hand, Bcl-X(L) can neutralize Bad by sequestering it to mitochondria. In order to map the domains of Bcl-X(L) involved in inhibiting Bax and Bad, we have carried out mutational analyses of this protein. This was done by deleting the key domains of Bcl-X(L), including its BH1-4 domains, the flexible loop, the C-terminal hydrophobic domain, and segments of the alpha5-alpha6 hairpin. The resulting Bcl-X(L) mutant constructs were then co-transfected with either GFP-Bax or GFP-Bad. We found that the BH1-4 domains and the C-terminal segment of Bcl-X(L) were essential for blocking Bax localization to mitochondria. On the other hand, only its BH1 and BH3 domains and the C-terminal hydrophobic segment were necessary for sequestering Bad to mitochondria. In addition, by immunoprecipitation analyses, we found that these deletions differentially affected the ability of the Bcl-X(L) mutant proteins to bind Bax and Bad. Finally, cell viability assays indicated that the BH1-4 domains of Bcl-X(L) were the primary domains required for inhibiting staurosporine-induced apoptosis, suggesting that distinct domains of Bcl-X(L) are involved in antagonizing Bax and Bad and in apoptosis inhibition.

Animals↗

PubMed2005

Maladaptive role of IL-6 in ischemic acute renal failure.

The role of IL-6 was investigated in murine ischemic acute renal failure. The renal pedicles were clamped for 17 min, and the mice were studied at various times after reperfusion. We found that serum IL-6 increased after murine ischemic renal injury. This increase was associated with increased IL-6 mRNA in the ischemic kidney but not in the contralateral kidney or the liver. Maximal IL-6 production occurred at 4 to 8 h and decreased to baseline by 24 h. Reperfusion of the kidney was required for IL-6 production. In situ hybridization and immunohistochemistry showed that macrophages infiltrated areas adjacent to the vascular bundles in the outer medulla within hours of reperfusion and showed that these macrophages produced IL-6 mRNA. For understanding how macrophages were stimulated to produce IL-6, an in vitro model in which S3 proximal tubular cells were injured by reactive oxygen species was set up. These injured cells released molecules that activated macrophages to produce IL-6 in vitro. IL-6 that was produced in response to renal ischemia was maladaptive because transgenic knockout of IL-6 ameliorated renal injury as measured by serum creatinine and histology. IL-6 transgenic knockout mice were lethally irradiated, and their bone marrow was reconstituted with wild-type IL-6 cells. Such bone marrow transfers abolished the protective effects of transgenic IL-6 knockout. It is concluded that macrophages infiltrate the area of the vascular bundles of the outer medulla, these macrophages produce IL-6, and this IL-6 exacerbates ischemic murine acute renal failure.

Acute Kidney Injury↗

PubMed2005

Hemoglobin-based hydrogen peroxide biosensor tuned by the photovoltaic effect of nano titanium dioxide.

The photovoltaic effect of titanium dioxide (TiO2) nanoparticles, induced by ultraviolet light, can greatly improve the catalytic activity of hemoglobin as a peroxidase, with the sensitivity increased nearly 3-fold and the detection limit lowered 2 orders, in contrast to the catalytic reactions in the dark, which indicates a possible method to tune the properties of proteins for development of photocontrolled protein-based biosensors.

Animals↗

PubMed2005

Rtt106p is a histone chaperone involved in heterochromatin-mediated silencing.

Epigenetic inheritance of heterochromatin structure is an important cellular process whose mechanism remains elusive. In this article, we describe the identification of nine enhancers of the silencing defect of a Saccharomyces cerevisiae-PCNA mutant by screening a library of approximately 4,700 viable yeast deletion mutants. Of the nine mutants identified, six (hir1, hir3, sas2, sas4, sas5, and sir1) were previously known to reduce silencing synergistically with a mutation in Cac1p, the large subunit of chromatin assembly factor 1 (CAF-1). The predicted gene products that are affected in three other mutants (nam7, msh2, and rtt106) have not been implicated previously in silencing. Characterization of the rtt106Delta allele revealed that it synergistically reduced heterochromatin silencing when combined with a mutation in Cac1p but not with a mutation in Asf1p (a histone H3 and H4 chaperone). Moreover, Rtt106p interacted with histones H3 and H4 both in vitro and in vivo, and it displayed a nucleosome assembly activity in vitro. Furthermore, Rtt106p interacts with CAF-1 physically through Cac1p. These biochemical and genetic data indicate that Rtt106p is a previously uncharacterized histone chaperone connecting S phase to epigenetic inheritance.

Chromatin Assembly and Disassembly↗

PubMed2005

Hilbert transform assisted complex wavelet transform for neuroelectric signal analysis.

In this work, we present a new approach for shift invariant complex wavelet analysis of neuroelectric signals. A key idea is to preprocess the signal with the Hilbert transformer to yield an analytic signal, which is then wavelet transformed using the linear phase complex scaling and wavelet filters. In different scales, the total energy of the wavelet transform coefficients is shift invariant. The decimated analytic wavelet coefficients suffer no aliasing effects, which are predominant in conventional wavelet analysis. We show the usefulness of the present method in multi-scale analysis of the neuroelectric signal waveforms.

Action Potentials↗

PubMed2005

High diversity of endophytic fungi from the pharmaceutical plant, Heterosmilax japonica Kunth revealed by cultivation-independent approach.

Heterosmilax japonica Kunth is well recognized for its diuretic effects in China. However, little is known about its endophytic fungi. In this study, microbial communities inhabiting the stems of H. japonica in spring and summer were investigated by light microscopy and cultivation-independent approaches, such as RFLP analysis and sequencing of rDNA ITS library. Molecular phylogenetic analysis showed that a broad spectrum of fungi, including Mycosphaerella, Phomopsis, Aureobasidium, Cladosporium, Glomerella, Botryosphaeria, Guignardia, is able to colonize the plants internally. Particularly, several rDNA sequences determined in this study like YJ4-61 are not specifically affiliated with any currently documented fungal sequences in the public database. Several sequence types, such as YJ4-9 and YJ4-70, are significantly similar to some uncultured environmental samples. Furthermore, our result also showed that the samples collected in spring harbored more abundant endophytic populations than that in summer, implying a seasonal fluctuation for the endophytes in H. japonica.

Ascomycota↗

PubMed2005

Effect of nano cadmium sulfide on the electron transfer reactivity and peroxidase activity of hemoglobin.

Hemoglobin (Hb) is immobilized with cadmium sulfide (CdS) nanoparticles (NPs) on pyrolytic graphite (PG) electrode to characterize the electrochemical reactivity and peroxidase activity of the protein. The result demonstrates that fine redox waves of Hb can be achieved after this protein is entrapped in CdS NPs. Meanwhile, the protein can exhibit nice catalytic activity towards hydrogen peroxide (H2O2). Linear relationship between the reductive peak current and the H2O2 concentration has been obtained from 5.0 x 10(-6) to 4.0 x 10(-4) mol/L, on the basis of which a new kind of H2O2 biosensor might be developed in the future.

Biosensing Techniques↗

PubMed2005

Genome-wide analyses of two families of snoRNA genes from Drosophila melanogaster, demonstrating the extensive utilization of introns for coding of snoRNAs.

Small nucleolar RNAs (snoRNAs) are an abundant group of noncoding RNAs mainly involved in the post-transcriptional modifications of rRNAs in eukaryotes. In this study, a large-scale genome-wide analysis of the two major families of snoRNA genes in the fruit fly Drosophila melanogaster has been performed using experimental and computational RNomics methods. Two hundred and twelve gene variants, encoding 56 box H/ACA and 63 box C/D snoRNAs, were identified, of which 57 novel snoRNAs have been reported for the first time. These snoRNAs were predicted to guide a total of 147 methylations and pseudouridylations on rRNAs and snRNAs, showing a more comprehensive pattern of rRNA modification in the fruit fly. With the exception of nine, all the snoRNAs identified to date in D. melanogaster are intron encoded. Remarkably, the genomic organization of the snoRNAs is characteristic of 8 dUhg genes and 17 intronic gene clusters, demonstrating that distinct organizations dominate the expression of the two families of snoRNAs in the fruit fly. Of the 267 introns in the host genes, more than half have been identified as host introns for coding of snoRNAs. In contrast to mammals, the variation in size of the host introns is mainly due to differences in the number of snoRNAs they contain. These results demonstrate the extensive utilization of introns for coding of snoRNAs in the host genes and shed light on further research of other noncoding RNA genes in the large introns of the Drosophila genome.

Animals↗

PubMed2005

Gonadoblastoma: evidence for a stepwise progression to dysgerminoma in a dysgenetic ovary.

Gonadoblastomas are neoplasms of dysgenetic gonads which may undergo regression or become overgrown by malignant germ cell tumors (mGCTs). Since little is known about their relationship to normal gonadal development and mGCTs, we studied the phenotype and antigenic profile of gonadoblastomas in comparison with adjacent dysgerminomas and fetal gonads. Three cases of gonadoblastomas and fetal gonads of both sexes were analyzed using oncofetal markers to M2A-antigen (M2A), germ cell alkaline phosphatase (PLAP/GCAP), receptor tyrosine kinase c-kit (c-kit), and somatic angiotensin converting enzyme (sACE) as well as the proliferation marker MIB-1. Morphologically, microfollicular pattern of gonadoblastomas showed a fetal germ cell organization reminiscent of oocytic clusters of fetal ovaries. They contained both cell types, similar to oocytes (M2A-, GCAP-, c-kit+/-, sACE-) and oogonia (M2A+, GCAP+, c-kit+, sACE+). The percentage of germ cells immunoreactive for oncofetal markers and the proliferation index increased from microfollicular over coronary patterns to adjacent dysgerminomas. Supportive cells of gonadoblastomas showed a uniform phenotype (CK18+, vimentin+, sACE+, alpha-inhibin+, M2A-) but in contrast to fetal germ cells lacked a clear equivalence to fetal tissues. Our results show that gonadoblastomas mimic female fetal ovary and exhibit a stepwise progression from follicular pattern to coronary pattern and finally to dysgerminomas.

Adolescent↗

PubMed2005

Electrochemistry of sinapine and its detection in medicinal plants.

Sinapine (O-sinapoyl choline) is a crucial component, with much medicinal value, of many dietary and medicinal plants. It has been found that sinapine gives an electrochemical response at a pyrolytic graphite electrode. The electrochemical properties of sinapine have been investigated. The peak current in the cyclic voltammogram is linear in the concentration range 1.9 x 10(-6)-2.5 x 10(-4) mol L(-1) and the limit of detection is 9.9 x 10(-7) mol L(-1). These properties can be applied to the determination of sinapine in extracts from three kinds of medicinal plant. The electrochemical method reported here is highly selective, sensitive, and stable.

Choline↗

PubMed2005

A new method for purification of recombinant human alpha-synuclein in Escherichia coli.

alpha-Synuclein (AS), a major component of Lewy body in Parkinson's disease patients, exists as a natively unfolded protein in physiological buffer. We recently found that the overexpressed AS in Escherichia coli bearing the cloned AS cDNA with no signal sequence was actually located inside the periplasm, but not in the cytoplasm as generally recognized. Therefore, a new protocol for preparing recombinant AS has been developed with only two steps: (1) osmotic shock for release of AS-containing periplasm fraction and (2) ion-exchange chromatography for further purification of AS. By using plasmids and E. coli strains commonly used the new protocol is much more convenient, faster, and cheaper compared to the current methods established since 1994. About 80 mg AS with 95% purity can be regularly prepared from a 1L culture in 3 days.

Chromatography, Gel↗

PubMed2005

Identification of 20 snoRNA-like RNAs from the primitive eukaryote, Giardia lamblia.

From a specialized cDNA library of Giardia lamblia, 20 snoRNA-like RNAs, including 16 box C/D sRNAs and four box H/ACA sRNAs, were first identified. The sRNAs were predicted to guide a total of 11 2'-O-methylation and four pseudouridylation sites on the G. lamblia rRNAs, respectively. By using primer extension assay, seven methylation sites were precisely mapped in the G. lamblia 16S rRNA, despite its high GC content. All of the sRNA genes locate on the small intergenic regions of the G. lamblia genome and seem to be independently transcribed from their own promoters. Particularly, a cluster composed of GlsR17 and GlsR18 genes is transcribed as a dicistronic precursor, implying a mechanism of endonuclease cleavage for the maturation of the two sRNAs. The systematic identification of the sRNAs in G. lamblia has provided valuable information about the characteristics of the two major families of small guide RNAs in one of the most primitive eukaryotes and would contribute to the understanding of the evolution of small non-messenger RNA genes from prokaryotes to eukaryotes.

Animals↗

PubMed2005

Proton di-ionizable p-tert-butylcalix[4]arene-crown-6 compounds in cone, partial-cone and 1,3-alternate conformations: synthesis and alkaline earth metal cation extraction.

Novel proton di-ionizable p-tert-butylcalix[4]arene-crown-6 compounds in cone, partial-cone and 1,3-alternate conformations are synthesized to compare the efficiency and selectivity with which they extract alkaline earth metal ions. In these ligands, a crown-6 polyether unit links alternate aromatic rings of the calix[4]arene framework. To the remaining lower-rim positions are attached oxyacetic acid or N-(X)sulfonyl oxyacetamide groups. Changing the conformation varies the spatial relationship between a polyether-complexed divalent metal ion and the ionized side arms of the ligands. This is found to markedly affect the efficiency and selectivity in competitive solvent extraction of alkaline earth metal ions from aqueous solutions into chloroform by the di-ionizable calix[4]arene-crown-6 ligands.

Journal Article↗

PubMed2005

Role of CYP2C9 and its variants (CYP2C93 and CYP2C913) in the metabolism of lornoxicam in humans.

CYP2C9 is an important member of the cytochrome P450 enzyme superfamily with some 12 CYP2C9 alleles (*1-*12) being previously reported. Recently, we identified a new CYP2C9 allele with a Leu90Pro mutation in a Chinese poor metabolizer of lornoxicam [Si D, Guo Y, Zhang Y, Yang L, Zhou H, and Zhong D (2004) Pharmacogenetics 14:465-469]. The new allele, designated CYP2C9*13, was found to occur in approximately 2% of the Chinese population. To examine enzymatic activity of the CYP2C9*13 allele, kinetic parameters for lornoxicam 5'-hydroxylation were determined in COS-7 cells transiently transfected with pcDNA3.1 plasmids carrying wild-type CYP2C9*1, variant CYP2C9*3, and CYP2C9*13 cDNA. The protein levels of cDNA-expressed CYP2C9*3 and *13 in postmitochondrial supernatant (S9) from transfected cells were lower than those from wild-type CYP2C9*1. Mean values of Km and Vmax for CYP2C9*1, *3, and *13 were 1.24, 1.61, and 2.79 microM and 0.83, 0.28, and 0.22 pmol/min/pmol, respectively. Intrinsic clearance values (Vmax/Km) for variant CYP2C9*3 and CYP2C9*13 on the basis of CYP2C9 protein levels were separately decreased to 28% and 12% compared with wild type. In a subsequent clinical study, the AUC of lornoxicam was increased by 1.9-fold and its oral clearance (CL/F) decreased by 44% in three CYP2C9*1/*13 subjects, compared with CYP2C9*1/*1 individuals. This suggests that the CYP2C9*13 allele is associated with decreased enzymatic activity both in vitro and in vivo.

Alleles↗

PubMed2005

Identification and functional analysis of 20 Box H/ACA small nucleolar RNAs (snoRNAs) from Schizosaccharomyces pombe.

Considering all small nucleolar RNAs (snoRNAs) enriched in the nucleolus, we generated a specialized cDNA library of small nuclear RNAs from Schizosaccharomyces pombe and isolated, for the first time, 20 novel box H/ACA snoRNAs. Thirteen of these were characterized as novel guides that were predicted to direct 19 pseudouridylations in 18 S and 25 S rRNAs. The remaining seven snoRNAs were considered as orphan guides that lack sequence complementarity to either rRNAs or snRNAs. We have experimentally demonstrated the function of the 10 novel snoRNAs by gene deletion in the fission yeast. The snoRNAs were shown to be dispensable for the viability of S. pombe, although an impact of snR94 depletion on yeast growth, especially at 23 degrees C, was revealed. A total of 30 pseudouridylation sites were precisely mapped in the S. pombe rRNAs, showing a distinctive pseudouridylation pattern in the budding yeast. Interestingly, the absence of pseudouridylation on U2347 in S. pombe 25 S rRNA pointed out a critical role for Psi2345 in conferring a growth advantage for yeast. In contrast to the intron-encoded box C/D sno-RNAs in yeast, all box H/ACA snoRNAs appeared to be transcribed independently from intergenic regions between two protein-coding genes, except for snR35, which was nested in an open reading frame encoding for a hypothetical protein, although expressed from the opposite strand. Remarkably, snR90 was cotranscribed with an intron-encoded box C/D snoRNA, and this is the first demonstration of a non-coding RNA gene that encodes two different types of snoRNAs by its exon and intron. A detailed comparison of the S. pombe snoRNAs, with their functional homologues in diverse organisms, suggests a mechanism by which the snoRNAs have evolved in coordination with rRNAs to preserve the post-transcriptional modification sites among distant eukaryotes.

Nucleic Acid Conformation↗

PubMed2005

Separation and characterization of synthetic impurities of triclabendazole by reversed-phase high-performance liquid chromatography/electrospray ionization mass spectrometry.

A simple high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) method for the separation and characterization of impurities in the synthesis of triclabendazole has been developed. The analytical separation was achieved on a reversed-phase C18 column using acetonitrile and water (60:40, v/v) as mobile solvent at a flow-rate of 1.0 ml/min at 25 degrees C, and an UV detection at 230 nm. The on-line HPLC/ESI-MSn examinations were performed using ion trap analyzer with extraction ion chromatography (EIC) technique in positive or negative ion modes. The semi-preparative separation was performed with a reversed-phase column using methanol and water (75:25, v/v) as mobile solvent at a flow-rate of 4 ml/min at 25 degrees C, and an UV detection at 230 nm. Thus, two impurities were detected and identified as 5-chloro-6-(2,3,4-trichlorophenoxy)-2-methylsulfanyl-1H-benzoimidazole and 5-chloro-6-(2,3-dichlorophenoxy)-1-methyl-2-methylsulfanyl-1H-benzoimidazole. Meanwhile, some intermediates of impurity-1 in multi-step synthetic reactions, were tracked. Structural elucidation by 1D and 2D NMR and ESI-MSn was discussed.

Benzimidazoles↗

PubMed2005

The complete mitochondrial genome of a tree frog, Polypedates megacephalus (Amphibia: Anura: Rhacophoridae), and a novel gene organization in living amphibians.

In this study, we have determined the complete sequence of the mitochondrial genome of an Old World tree frog Polypedates megacephalus (Anura: Rhacophoridae) by using a long polymerase chain reaction (PCR) technique and shotgun strategy of sequencing. The entire mtDNA sequence is 16,473 nt long with a novel mitogenomic gene organization in amphibians. Unlike other neobatrachian frogs, the transfer ribonucleic acid (tRNA)-Leu(CUN) and tRNA-Thr genes exchange their positions in P. megacephalus and form a Thr-Leu(CUN)-Pro-Phe tRNA gene tetrad. Moreover, we found that the ATP8 gene was replaced by a noncoding sequence of 853 nt long and that the ND5 gene was absent in the new mitogenome. These peculiar features of P. megacephalus mtDNA were further studied among related anuran species by PCR amplification. The new sequence data was used to assess the phylogenetic relationships of the three living amphibian orders using neighbor-joining, maximum likelihood, and Bayesian methods. In agreement with most morphological studies, phylogenetic analyses of a whole mitochondrial genome data set suggest a close relationship between salamanders and frogs. Moreover, using a molecular clock-independent Bayesian approach for inferring dating information from molecular phylogenies, we have provided a rough timescale for living amphibian evolution. This timescale provides a working framework for future paleontological researches on amphibian evolution and improves our understanding of the evolutionary history of modern amphibians.

Animals↗

PubMed2005

Molecular phylogenetic diversity of bacteria associated with the leachate of a closed municipal solid waste landfill.

A 16S rDNA-based molecular study was performed to determine the nature of the bacterial constituents of the leachate from a closed municipal solid waste landfill. Total community DNA was extracted and bacterial 16S rRNA genes were subsequently amplified and cloned. Recombinant rDNA clones in the library were randomly selected, and they were sequenced for a single run and then grouped. A total of 76 sequence types representing 138 randomly selected nonchimeric clones were identified. Full-length sequencing and phylogenetic analysis of the sequence types revealed that more than 90% of the screened clones were affiliated with low-G+C gram-positive bacteria (38.4%), Proteobacteria (35.5%), the Cytophaga Flexibacter Bacteroides group (11.6%), and Spirochaetes (5.1%). Minor portions were affiliated with Verrucomicrobia (2.9%), candidate division OP11 (2.2%), and the green nonsulfur bacteria, Cyanobacteria and the Deinococcus Thermus group (each <1.0%). Although some rDNA sequences clustered with genera or taxa that were classically identified within anaerobic treatment systems and expected with known functions, a substantial fraction of the clone sequences showed relatively low levels of similarity with any other reported rDNA sequences and thus were derived from unknown taxa. These results suggest that bacterial communities in landfill environment are far more complex than previously expected and remain largely unexplored.

Bacteria↗