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Biomedical subjects

P Zhou

Publications and source records attributed to P Zhou.

At least 73 records · Page 4Linked to original sources
PubMed2000

The hPLIC proteins may provide a link between the ubiquitination machinery and the proteasome.

Although there is a binding site on the proteasome for the polyubiquitin chains attached to degradation substrates by the ubiquitination machinery, it is currently unclear whether in vivo the activities of the ubiquitination machinery and the proteasome are coupled. Here we show that two human homologs of the yeast ubiquitin-like Dsk2 protein, hPLIC-1 and hPLIC-2, physically associate with both proteasomes and ubiquitin ligases in large complexes. Overexpression of hPLIC proteins interferes with the in vivo degradation of two unrelated ubiquitin-dependent proteasome substrates, p53 and IkappaBalpha, but not a ubiquitin-independent substrate. Our findings raise the possibility that the hPLIC proteins, and possibly related ubiquitin-like family members, may functionally link the ubiquitination machinery to the proteasome to affect in vivo protein degradation.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Harnessing the ubiquitination machinery to target the degradation of specific cellular proteins.

The functional characterization of a specific gene, or its protein product, often relies on assessing the consequences of its elimination, usually accomplished by gene knockout, ribozyme, antisense, or RNA-mediated interference (RNAi) technologies. The selective degradation of cellular proteins is mediated primarily by the ubiquitin-proteasome pathway. Manipulation of the ubiquitin-dependent proteolytic machinery to eliminate specific gene products at the protein level has been previously attempted with some success in vitro; however, the in vivo efficacy of this approach has not yet been achieved. Here we report successful engineering of the substrate receptor of a major ubiquitin-proteolytic machinery to direct the degradation of otherwise stable cellular proteins both in yeast and in mammalian cells.

Animals↗
PubMed2000

Characterization of Micrococcus antarcticus sp. nov., a psychrophilic bacterium from Antarctica.

A Gram-positive, cold-adapted, aerobic, spherical actinobacterium (strain T2T) with a quite low cardinal growth temperature was isolated from Chinese Great-Wall station in Antarctica. Sequence comparisons of the 16S rDNA indicated the isolate to be a phylogenetic member of the genus Micrococcus, family Micrococcaceae, in which it represents a novel lineage. The phylogenetic distinctness of the isolate with respect to the type strains Micrococcus luteus and Micrococcus lylae was supported by DNA-DNA similarity values of less than 40%. Chemotaxonomic properties supported the placement of the isolate in the genus Micrococcus. The diagnostic diamino acid of the cell-wall peptidoglycan is lysine. The predominant menaquinones are MK-8 and MK-8(H2). The G + C content of the DNA of the isolate is 66.4 mol%. Genotypic, morphological and physiological characteristics were used to describe a new species of Micrococcus, for which the name Micrococcus antarcticus is proposed. The type strain is T2T (= AS 1.2372T).

Amino Acids↗
PubMed2000

Natrinema versiforme sp. nov., an extremely halophilic archaeon from Aibi salt lake, Xinjiang, China.

A novel extremely halophilic archaeon, strain XF10T, was isolated from a salt lake in China. This organism was neutrophilic, non-motile and pleomorphic, and was rod, coccus or irregularly shaped. It required at least 1.5 M NaCl for growth and grew in a wide range of MgCl2 concentrations (0.005-0.5 M). Lipid extract of whole cells contained two glycolipids with the same chromatographic properties as two unidentified glycolipids found in the two described Natrinema species, Natrinema pellirubrum and Natrinema pallidum. Phylogenetic analysis based on 16S rDNA sequence comparison revealed that strain XF10T clustered with the two described Natrinema species and several other strains (strains T5.7, GSL-11 and Haloterrigena turkmenica JCM 9743) with more than 98.1% sequence similarities, suggesting that strain XF1OT belongs to the genus Natrinema. Comparative analysis of phenotypic properties and DNA-DNA hybridization between strain XF10T and the Natrinema species supported the conclusion that strain XF10T is a novel species within the genus Natrinema. The name Natrinema versiforme sp. nov. is proposed for this strain. The type strain is XF10T (=JCM 10478T=AS 1.2365T=ANMR 0149T).

Base Composition↗
PubMed2000

Ethyl 5-methyl-4-(2,5,5-trimethyl-1, 3-dioxan-2-yl)isoxazole-3-carboxylate.

The title compound, C(14)H(21)NO(5), possesses an isoxazolyl group in the axial position of the 1,3-dioxanyl ring. The two rings are rotated about the bond joining them such that the two C(methyl)-C(dioxanyl)-C-C torsion angles are 92.1 (2) and -84.1 (2) degrees. In this conformation, neither the methyl nor ethoxycarbonyl substituents on the isoxazole are presented towards the dioxanyl chair.

Crystallography, X-Ray↗
PubMed2000

[Experiments on elimination of the noise in NEMG by adopting wavelet transform].

Wavelet transform (WT) is a promising technique for time-frequency analysis. By decomposing signals into elementary building blocks that are well localized both in time and frequency, the WT can characterize the local regularity of signal. In this paper, we process the needle electrode electromyography (NEMG) signal with noise by adopting WT and have completed the contrast experiments. The results show that WT is an effective method by which high frequency noise and baseline drift in NEMG can successfully be eliminated by selecting proper transform scales of WT.

Electromyography↗
PubMed2000

A distinct mutational spectrum of p53 and K-ras genes in lung cancer of workers with silicosis.

Crystalline silica was recently classified as a human carcinogen by the International Agency for Research on Cancer (IARC). However, the direct genotoxic effect of silica in humans remains unclear. We examined the p53 and K-ras gene mutations in lung cancer in workers with silicosis (LCWS). DNA was extracted from paraffin-embedded tissues and examined by PCR-RFLP, PCR-SSCP, and DNA sequencing. The mutation frequencies of p53 gene were high, but the mutation distributions in exons and among the histological types of LCWS differed from those of common (i.e., not silicosis-related) lung cancer. Furthermore, no mutations in codon 12 of K-ras gene (predominant in common lung cancer) were found in LCWS. These findings in the mutational spectrum support a carcinogenic effect of silica dust at the DNA molecular level.

DNA Mutational Analysis↗
PubMed2000

Rejection of capillary wall background light in an on-column confocal fluorescence detector.

Minimization of the background arising from the capillary wall is of extreme importance in laser induced fluorescence on-column detection for capillary electrophoresis. A sensitive confocal fluorescence detection scheme is described. The intense capillary wall background light was effectively rejected by an adjustable precision slit in a confocal configuration. Rhodamine 640 was used as a standard fluorophore. Detection linearity was demonstrated over four orders of magnitude of concentration and the concentration detection limit was 3.38 x 10(-11) M.

Journal Article↗
PubMed2000

Impaired gp-91phox gene expression and dysfunction of peripheral blood neutrophils in patients maintaining hemodialysis.

OBJECTIVE: To investigate expressions of gp-91phox and IL-8 gene and the function of neutrophils in hemodialysis (HD) patients, and to understand the relationship between uremia and immune. METHODS: Gene expression was studied by means of reversal transcription polymerase chain reaction (RT/PCR) from the untreated and treated with lipopolysaccharide (LPS) neutrophils in controls and HD patients. Phagocytosis and bactericidal assays were measured as a decrease in the number of viable intracellular and extracellular bacteria by colony counts. RESULTS: Freshly isolated neutrophils express gp-91phox mRNA in controls while no gp-91phox mRNA was detected in HD patients. When challenged with LPS, gp-91phox mRNA exhibited decreased expression. IL-8 mRNA in HD patients could be spontaneously expressed. Phagocytosis and intracellular killing of neutrophils, when exposed to Staphylococcus aureus, were decreased obviously compared with controls. CONCLUSIONS: The impaired gp-91phox gene expression of neutrophils indicates the impaired NADPH-oxidase system and the untreated neutrophils spontaneously express IL-8 mRNA in the HD patients, which is consistent with suppressed phagocytosis and intracellular killing capacity.

Cell Division↗
PubMed2000

[Effect of temperature on the activity of some enzymes representative of EMP pathway and TCA cycle in psychrophilic yeast].

Some key enzymes of EMP pathway and TCA cycle in a psychrophilic yeast Y18 were studied in this paper compared with those of Saccharomyces cerevisiae. The results indicated that fructose, 1,6-bisphosphate aldolase, succinate dehydrogenase, and hexokinase in Y18 were very thermolabile and have high activity at low temperature. These enzymes belong to cold-active enzymes. Alpha-ketoglutarate dehydrogenase existed possibly in isoenzyme which had different temperature characteristics. Citrayl synthetase was very similar in temperature characteristics to that of mesophiles. The Km value of succinate dehydrogenase both from Y18 and S. cerevisiae were studied and Some features of enzyme in psychrophiles were also discussed in this paper.

Cryptococcus↗
PubMed2000

[Taxonomy of a new species of haloalkalophilic archaeon].

A strain of Haloalkalophilic Archaeon Y21 was isolated from soda lake in Inner Mongolia Autonomous Region. The isolate is rod shaped, motile and red clone. On the basis of morphology, physiology and biochemistry, polar lipid composition, phylogentic analysis and DNA-DNA hybridization, we found that strain Y21 is new species of the genus Natrilba. The name Natrilba wudunaoensis sp. nov. is proposed.

DNA, Archaeal↗
PubMed2000

[Molecular cloning and expression of E2 gene of the Chinese classical swine fever virus(shimen strain) and preliminary studies of its DNA vaccine].

A 1.1 bp fragment of E2 gene of Chinese classical swine fever virus(CSFV) Shimen strain, a standard virulent strain, was amplified by RT-PCR from total RNA of cell cultures infected by CSFV, and cloned into pGEM T vector. The nucleotide sequence of this fragment was sequenced by Sanger's method and the amino acid sequence was deduced. Compared with the corresponding region of Alfort, Brescia and C strain of CSFV, the nucleotide sequence homology is 84.7%, 92.6% and 95.2% respectively, and the amino acid sequence 89.4%, 92.6% and 94.6%, respectively, we subcloned 1.1 bp of E2 gene cDNA into baculovirus transfer vector and successfully constructed two recombinant baculoviruses expressing GST-E2 and GST-GFP-E2 fusion protein respectively by homologous recombination in sf-9 cell. Furthermore, we also constructed recombinant eukaryotic expression vector pcE2 containing E2 gene in frame and transfected COS-7 cell by lipofectamine, the indirect immunofluorescence assay (IFA) showed that the expressed E2 protein can be recognized by E2 specific monoclonal antibody the pcE2 DNA was directly injected into BALB/c mice intramuscular(i.m.) and the CSFV E2-specific antibodies was measured by enzyme-linked immunosorbent assay(ELISA) the ELISA results indicated the E2-specific antibodies was induced in inoculated mice and virus neutralization assays also indicate single inoculations of plasmids expressing CSFV E2 glycoprotein raised neutralizing antibody in BALB/c mice. these results will be beneficial to investigate the possibility of DNA vaccine against CSFV.

Amino Acid Sequence↗
PubMed2000

[Studies on chemical components of the volatile oil from the leaves of Hypericum perforatum].

OBJECTIVE: To determine the volatile oil of the leaves from Hypericum perforatum L.. METHOD: The essential oil was obtained by simultaneous distillation and solvent extraction. The chemical components were seperated and identified by GC-MS. The relative contents in the volatile oil were determined by area nomalization. RESULTS: 54 chemical constituents were separated and identified representing 92.32% of the total contents. CONCLUSION: Sesquiterpenes are major chemical constituents in the oil from the leaves of Hypericum perforatum L.. They are very different from those of the essential oil from the same species from the other country.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

Solution structure of the CIDE-N domain of CIDE-B and a model for CIDE-N/CIDE-N interactions in the DNA fragmentation pathway of apoptosis.

Apoptotic DNA fragmentation and chromatin condensation are mediated by the caspase-activated DFF40/ CAD nuclease, which is chaperoned and inhibited by DFF45/ICAD. CIDE proteins share a homologous regulatory CIDE-N domain with DFF40/CAD and DFF45/ ICAD. Here we report the solution structure of CIDE-N of human CIDE-B. We show that the CIDE-N of CIDE-B interacts with CIDE-N domains of both DFF40 and DFF45. The binding epitopes are similar and map to a highly charged bipolar surface region of CIDE-B. Furthermore, we demonstrate that the CIDE-N of CIDE-B regulates enzymatic activity of the DFF40/ DFF45 complex in vitro. Based on these results and mutagenesis data, we propose a model for the CIDE-N/ CIDE-N complex and discuss the role of this novel bipolar interaction in mediating downstream events of apoptosis.

Amino Acid Sequence↗
PubMed1999

Protection from cell death by mcl-1 is mediated by membrane hyperpolarization induced by K(+) channel activation.

Mcl-1, a member of the Bcl-2 family, has been identified as an inhibitor of apoptosis induced by anticancer agents and radiation in myeloblastic leukemia cells. The molecular mechanism underlying this phenomenon, however, is not yet understood. In the present study, we report that hyperpolarization of the membrane potential is required for prevention of mcl-1 mediated cell death in murine myeloblastic FDC-P1 cells. In cells transfected with mcl-1, the membrane potential, measured by the whole-cell patch clamp, was hyperpolarized more than -30 mV compared with control cells. The membrane potential was repolarized by increased extracellular K(+) concentration (56 mV per 10-fold change in K(+) concentration). Using the cell-attached patch-clamp technique, K(+) channel activity was 1.7 times higher in mcl-1 transfected cells (NP(o) = 22.7 +/- 3. 3%) than control cells (NP(o) = 13.2 +/- 1.9%). Viabilities of control and mcl-1 transfected cells after treatment with the cytotoxin etoposide (20 microgram/ml), were 37.9 +/- 3.9% and 78.2 +/- 2.0%, respectively. Suppression of K(+) channel activity by 4-aminopyridine (4-AP) before etoposide treatment significantly reduced the viability of mcl-1 transfected cells to 49.0 +/- 4.6%. These results indicate that as part of the prevention of cell death, mcl-1 causes a hyperpolarization of membrane potential through activation of K(+) channel activity.

4-Aminopyridine↗