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Biomedical subjects

Z Yu

Publications and source records attributed to Z Yu.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Adrenomedullin and hypoxia-induced pulmonary hypertension].

OBJECTIVE: To study adrenomedullin (AM) in rat and human lung during hypoxia-induced pulmonary hypertension. METHODS: Normobaric hypoxic pulmonary hypertension animal model was adopted, pulmonary artery pressure and RVdp/dt were measured. The changes of AM contents in blood and bronchoalveolar lavage fluid were studied. The plasma levels of AM in patients with pulmonary hypertension were measured. RESULTS: During hypoxia, pulmonary artery pressure, RVdp/dt, AM contents in blood and bronchoalveolar lavage fluid in rats increased. Plasma levels of AM were significantly higher in patients with pulmonary hypertension than in the control subjects. CONCLUSIONS: AM may play an important role in developing hypoxic pulmonary hypertension in rats and human. The increase of AM level is in proportion to the extent of pulmonary hypertension.

Adrenomedullin↗
PubMed2001

[Invasive rhinocerebral aspergillosis occurred during myelosuppressive phase after chemotherapy: a case report and literature review].

OBJECTIVE: To report a case of invasive rhinocerebral aspergillosis (IRA) during myelosuppressive phase after chemotherapy and the treatment outcome. METHODS: A patient with acute non-lymphoblastic leukemia (M(2a)) occurred IRA during myelosuppressive phase after chemotherapy and was treated with amphotericin B (AmB, including AmB-L), garlicin, 5-flucytosine (5-FC), fluconazole, itraconazole, ketoconazole, econazole and griseofulvin with twice of cerebrotomy lesion resections and cerebral decompressions. RESULTS: Though the survival time of this patient is a little longer than the others, she finally died of uncontrolled infection. CONCLUSION: For most of the IRA, there remains no effective treatment. The best treatment is AmB in combination with surgical excision.

Adult↗
PubMed2001

[Synthesis and release of pulmonary tissue adrenomedullin on hypoxic pulmonary hypertension in rats and its significance].

OBJECTIVE: To investigate the synthesis and release of adrenomedullin (AM) of lung tissue in rats on hypoxic pulmonary hypertension (HPH) and study its mechanism and significance in the pathogenesis process of HPH. METHODS: 54 Wistar rats were divided into hypoxia 10 d (n = 12), 20 d (n = 12), 30 d (n = 12) groups and control group (n = 18). The rats of hypoxia groups were exposed to chronic hypobaric hypoxia environment at high 5 km to establish HPH models. The expression of pulmonary cell AM protein, the content of plasma AM and bronchial alveolar lavage fluid (BALF) AM were determined by optical microscopy, immunohistochemistry and radio-immunoassay. RESULTS: AM was widely distributed in lung tissue. There was positive of AM in intraplasma of vascular endothelial cells (EC), vascular and bronchial smooth muscular cells (SMC), bronchial epithelial cells, macrophages (M phi) and type II alveolar epithelial cells in every groups. After hypoxia, the expression of AM in above cells, especially EC, SMC and M phi, increased more than control group. Plasma AM contents of hypoxia groups were higher than control group(P < 0.01). 20 d after hypoxia, the AM content was twice as control group. At 10 d to 20 d after hypoxia, BALF AM content was increased more than control group (P < 0.01). But at 30 d the content was decreased near to normal. CONCLUSIONS: Hypoxia is effective in promoting AM synthesis and release in pulmonary tissue and suggestes that AM as a peptide plays an important regulating role on pulmonary circulation, exchange of air and pulmonary vascular structural remodeling in the pathophysiological process of HPH.

Adrenomedullin↗
PubMed2001

[Two terms tympanoplasty in chronic suppurative otitis media].

OBJECTIVE: To explore the clinical manifestations and therapeutic effects of treating chronic suppurative otitis media with two terms tympanoplasty. METHOD: 36 patients were retrospectively analyzed. The criterions of success are air room in middle ear, intact eardrum and decrease of A-B gape in audiometry. RESULT: 32 cases of all patients got successful effects, 4 cases failed. The main cause of failure is to fail forming air room in middle ear. CONCLUSION: The two term's tympanoplasty can save the residual hearing in most patient. But it is difficult to get successful result if more mucous membrane in the middle ear disappeared.

Adolescent↗
PubMed2001

[Transmission electron microscopy of the tegmentum vasculosum in chick inner ear].

OBJECTIVE: To study the ultrastructure of the tegmentum vasculosum(TV) in chick inner ear so as to obtain important information for its physiology and pathology. METHOD: The ultrastructures of TV in 20 chicks were observed by transmission electron microscope(TEM). RESULT: TV was composed of flask-shaped dark cells, which had dense cytoplasm; hourglass-shaped light cells, which had light cytoplasm; abundant microvascula. Dark cell had the extensive networks of folded plasma membrane along the side and throughout the lower half of the cell, these folds of dark cell interdigitated with thin processes which extended from the lateral walls of light cell, these were sparse microvilli on the luminal surface of light cell and sparse cellular organizations in light cell. Light cell had more direct contacts with the micrangium. CONCLUSION: TV is very similar to stria vascularis but there are also some differences between them under TEM.

Animals↗
PubMed2001

[Cloning of parasporal body protein gene resembling to S-layer protein genes from Bacillus thuringiensis CTC strain].

Bacillus CTC strain was identified as Bacillus thuringiensis subsp. finitimus (serotype H2) and Pasteur Institute confirmed this identification. The parasporal body formed by CTC strain is oval shaped, and consists of 100 kD protein. The determination of the N-terminal amino acid sequence showed this protein shares 93% similarity to that of B. anthracis S-layer proteins. The restriction map covering the related protein gene (ctc) was deduced according to southern hybridization. The DNA fragments containing the 5' and 3' end of ctc gene with 0.6 kb overlap were isolated, respectively. Full length ctc gene was then constructed. B. thuringiensis is a species similar to B. cereus and B. anthracis, and only can be distinguished by forming parasporal bodies. The growth of E. coli maintaining ctc gene is similar to that of E. coli expressing S-layer protein gene. The above preliminary results showed that the parasporal body protein in CTC strain is a cell surface-like protein. So identifying CTC strain as a species of B. thuringiensis and the unique criterion for the identification of B. thuringiensis by forming parasporal body should be reconsidered.

Amino Acid Sequence↗
PubMed2001

[Transcriptional activator PlcR regulate the expression of multiple genes in Bacillus cereus].

Food-poisoning and some diseases of human can be caused by potential pathogenic factors including phospholipases of c-type, hemolysins, enterotoxins, emetic toxin and others from Bacillus cereus which is an opportunistic pathegon. Generally, the expression of pathogenic genes is completed by a co-regulation in many bacteria. The isolation of a mutant, displaying significant reducing expression of lecithinase and general proteolytic activities, from a transposon-induced bank of B. cereus type strain ATCC14579T were described. Sequencing data revealed that a gene with high homology to transcriptional activator (plcR) of B. thuringiensis was inactivated by insertion in this mutant. The results suggest that plcR regulates the expression of multiple genes in B. cereus.

Amino Acid Sequence↗
PubMed2001

[Establishment of fetal limb bud culture model of mouse].

In order to study the development of bone and the effect of each single factor on the metabolism of bone during gestation age, a self-made rotating apparatus was designed. The limb bud of fetal mouse at the 16th day of gestation was examined with the techniques of X-roentgenography and histological slices. Comparing with the uncultued control limbs, the test limb cultured for six days showed longer bone length and higher bone density. The cultured bone cells showed active differentiation, proliferation and increased bone trabecula by histological examination. It is concluded that the cultured bone continued developing and differentiating, which confirming the feasibility and reliability of the method.

Animals↗
PubMed2000

Soluble epoxide hydrolase regulates hydrolysis of vasoactive epoxyeicosatrienoic acids.

The cytochrome P450-derived epoxyeicosatrienoic acids (EETs) have potent effects on renal vascular reactivity and tubular sodium and water transport; however, the role of these eicosanoids in the pathogenesis of hypertension is controversial. The current study examined the hydrolysis of the EETs to the corresponding dihydroxyeicosatrienoic acids (DHETs) as a mechanism for regulation of EET activity and blood pressure. EET hydrolysis was increased 5- to 54-fold in renal cortical S9 fractions from the spontaneously hypertensive rat (SHR) relative to the normotensive Wistar-Kyoto (WKY) rat. This increase was most significant for the 14,15-EET regioisomer, and there was a clear preference for hydrolysis of 14, 15-EET over the 8,9- and 11,12-EETs. Increased EET hydrolysis was consistent with increased expression of soluble epoxide hydrolase (sEH) in the SHR renal microsomes and cytosol relative to the WKY samples. The urinary excretion of 14,15-DHET was 2.6-fold higher in the SHR than in the WKY rat, confirming increased EET hydrolysis in the SHR in vivo. Blood pressure was decreased 22+/-4 mm Hg (P:<0.01) 6 hours after treatment of SHRs with the selective sEH inhibitor N:, N:'-dicyclohexylurea; this treatment had no effect on blood pressure in the WKY rat. These studies identify sEH as a novel therapeutic target for control of blood pressure. The identification of a potent and selective inhibitor of EET hydrolysis will be invaluable in separating the vascular effects of the EET and DHET eicosanoids.

8,11,14-Eicosatrienoic Acid↗
PubMed2000

Binding interactions of vancomycin tracers with a bacterial cell wall peptidoglycan analogue.

Binding interactions between several vancomycin tracers and (N,N'-diacetyl)KDADA in solution were evaluated in a competition format using a surface plasmon resonance instrument. Tracers derivatized from the carboxy terminus or the N-vancosaminyl sugar moiety of vancomycin bind the peptide with an affinity similar to that of underivatized vancomycin. In contrast, N-methylleucyl derivatized vancomycin tracers bind the peptide with a reduced affinity relative to vancomycin.

Anti-Bacterial Agents↗
PubMed2000

Transposon diversity in Arabidopsis thaliana.

Recent availability of extensive genome sequence information offers new opportunities to analyze genome organization, including transposon diversity and accumulation, at a level of resolution that was previously unattainable. In this report, we used sequence similarity search and analysis protocols to perform a fine-scale analysis of a large sample ( approximately 17.2 Mb) of the Arabidopsis thaliana (Columbia) genome for transposons. Consistent with previous studies, we report that the A. thaliana genome harbors diverse representatives of most known superfamilies of transposons. However, our survey reveals a higher density of transposons of which over one-fourth could be classified into a single novel transposon family designated as Basho, which appears unrelated to any previously known superfamily. We have also identified putative transposase-coding ORFs for miniature inverted-repeat transposable elements (MITEs), providing clues into the mechanism of mobility and origins of the most abundant transposons associated with plant genes. In addition, we provide evidence that most mined transposons have a clear distribution preference for A + T-rich sequences and show that structural variation for many mined transposons is partly due to interelement recombination. Taken together, these findings further underscore the complexity of transposons within the compact genome of A. thaliana.

Amino Acid Sequence↗
PubMed2000

Human G protein gamma(11) and gamma(14) subtypes define a new functional subclass.

The mammalian gamma subunit family consists of a minimum of 12 members. Analysis of the amino acid sequence conservation suggests that the gamma subunit family can be divided into three distinct subclasses. The division of the gamma subunit family into these classes is based not only on amino acid homology, but also to some extent on functional similarities. In the present study, two new members of the gamma subunit family, the gamma(11) and gamma(14) subunits, are identified and characterized in terms of their expression and function. The gamma(11) and gamma(14) subunits are most closely related to the gamma(1) subunit and share similar biochemical properties, suggesting their inclusion in class I. However, despite their close phylogenetic relationship and similar biochemical properties, the gamma(1), gamma(11), and gamma(14) subunits exhibit very distinct expression patterns, suggesting that class I should be further subdivided and that the signaling functions of each subgroup are distinct. In this regard, the gamma(11) and gamma(14) subunits represent a new subgroup of farnesylated gamma subunits that are expressed outside the retina and have functions other than phototransduction.

Amino Acid Sequence↗
PubMed2000

Direct analysis of artemisinin in plasma and saliva using coupled-column high-performance liquid chromatography with a restricted-access material pre-column.

A previously established HPLC system with post-column derivatization for the analysis of artemisinin was coupled to an ADS (alkyl-diol silica) pre-column, allowing direct and repetitive injection of protein-rich fluids such as plasma. The limit of quantitation for 100 microl of plasma was 10 ng/ml (CV=10.5%) while concentrations down to 2 ng/ml could be quantified for 1.00 ml saliva samples (CV=11.1%). The system was linear in the tested range of 10-2000 ng/ml for plasma and 2-240 ng/ml for saliva samples, respectively. This paper introduces coupled column HPLC as a simplified method for the routine analysis of artemisinin in biological fluids.

Antimalarials↗
PubMed2000

The dominant negative LQT2 mutation A561V reduces wild-type HERG expression.

HERG(1) K(+) channel mutations are responsible for one form of dominantly inherited long QT syndrome (LQT). Some LQT mutations exert a dominant negative effect on wild-type current expression. To investigate mechanisms of dominant-negative behavior, we co-expressed wild-type HERG with the A561V mutant in mammalian cells. Transfection with various cDNA ratios produced HERG K(+) current densities that approached a predicted binomial distribution where mutant and wild-type subunits co-assemble in a tetramer with nearly complete dominance. Using C terminus myc-tagged wild-type HERG we specifically followed the mutant's effect on full-length wild-type HERG protein expression. Co-expression with A561V reduced the abundance of full-length wild-type HERG protein comparable to the current reduction. Reduction of wild-type protein was due to decreased synthesis and increased turnover. Conditions facilitating protein folding (growth at 30 degrees C, or in 10% glycerol) resulted in partial rescue from the dominant effect, as did the 26 S proteosome inhibitor ALLN. Thus, for A561V, dominant negative effects result from assembly of wild-type subunits with mutant very early in production leading to rapid recognition of mutant channels and targeting for proteolysis. These results establish protein misfolding, cellular proofreading, and bystander involvement as contributing mechanisms for dominant effects in LQT2.

Animals↗
PubMed2000

P(MeNCH2CH2)3N: an efficient catalyst for the desilylation of tert-butyldimethylsilyl ethers

tert-Butyldimethylsilyl (TBDMS) ethers of primary, secondary, and tertiary alcohols and phenolic TBDMS ethers are desilylated to their corresponding alcohols and phenols, respectively, in DMSO, at 80 degrees C, in 68-94% yield in the presence of 0.2-0.4 equiv of P(MeNCH2CH2)3N. Using P(i-PrNCH2-CH2)3N as the catalyst, 85-97% yields of desilylated alcohols were obtained from TBDMS ethers of 1-octanol, 2-phenoxyethanol, and racemic alpha-phenyl ethanol. These are the first examples of desilylations of silyl ethers catalyzed by nonionic bases. Both catalysts were much less effective for the desilylation of tert-butyldiphenylsilyl (TBDPS) ethers (22-45% yield) under the same conditions as used for TBDMS ethers. Possible pathways involving nucleophilic attack of the anion of the solvent molecule (generated by the catalyst) at the Si-O bond of silyl ether or a prior activation of the silyl ether by the catalyst via a P-Si interaction followed by nucleophilic attack of the solvent anion are proposed on the basis of 1H and 31P NMR experimental data.

Journal Article↗
PubMed2000

HER-2/neu blocks tumor necrosis factor-induced apoptosis via the Akt/NF-kappaB pathway.

Overexpression of HER-2/neu correlates with poor survival of breast and ovarian cancer patients and induces resistance to tumor necrosis factor (TNF), which causes cancer cells to escape from host immune defenses. The mechanism of HER-2/neu-induced TNF resistance is unknown. Here we report that HER-2/neu activates Akt and NF-kappaB without extracellular stimulation. Blocking of the Akt pathway by a dominant-negative Akt sensitizes the HER-2/neu-overexpressing cells to TNF-induced apoptosis and inhibits IkappaB kinases, IkappaB phosphorylation, and NF-kappaB activation. Our results suggested that HER-2/neu constitutively activates the Akt/NF-kappaB anti-apoptotic cascade to confer resistance to TNF on cancer cells and reduce host defenses against neoplasia.

3T3 Cells↗
PubMed2000

Abnormal expression of hepatoma specific gamma-glutamyl transferase and alteration of gamma-glutamyl transferase gene methylation status in patients with hepatocellular carcinoma.

BACKGROUND: Hepatoma specific gamma-glutamyl transferase (HS-GGT) bands were expressed in the development of hepatocellular carcinoma (HCC) and were associated with a high incidence of HCC diagnosis. The objectives of this study were to determine the levels of HS-GGT quantitatively in the sera of patients with different liver diseases. The methylational status of GGT gene CCGG sites was analyzed in hepatoma tissues. METHODS: The HS-GGT concentrations were quantitatively analyzed in the sera of 156 HCC patients and others with liver diseases or extrahepatic tumors. In 20 hepatoma tissues, the GGT enzyme proteins were purified, the activities of GGTs of different molecular form were examined, total RNAs were extracted and amplified by using a nested polymerase chain reaction (PCR) assay, and the methylational status of CCGG site (M3) in the 5'-noncoding region of GGT genes was investigated with the restriction enzyme Hpa II. RESULTS: Total GGT activities in patients with liver diseases and extrahepatic tumors were abnormally increased. The levels of serum HS-GGT were significantly elevated (P < 0.001) in the HCC group; the incidence of HS-GGT over 5.5 IU/L was 86% in HCC patients and less than 3% in patients with other diseases. From liver cancer to distal noncancerous tissues, an increasing tendency (P < 0.05) of total RNA concentrations was found; the frequencies of amplified fragment and hypomethylated M3 site of GGT genes were 100% and 75% in HCC, 85% and 55% in paracancerous tissues, and 75% and 50% in noncancerous tissues, respectively. An inverse correlation was found between methylational degrees of GGT genes and expression levels of GGT. CONCLUSIONS: The abnormal alteration of serum HS-GGT level is a sensitive tumor marker for HCC diagnosis or differentiation, and the overexpression of GGT in HCC may be related to the hypomethylational status of CCGG sites of GGT genes.

Adult↗