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Biomedical subjects

Z Yu

Publications and source records attributed to Z Yu.

At least 145 records · Page 8Linked to original sources
PubMed2000

[Characterization of the insecticidal crystal protein genes of Bacillus thuringiensis YBT-1520].

The insecticidal crystal protein genes of highly toxic Bacillus thuringiensis YBT-1520 were analyzed. Southern hybridization and PCR analysis indicated that this strain bears cry1Aa, cry1Ab, cry1Ac and cry2 genes. The copy number of three cry1A genes is different and cry1Ac gene (here named cry218) is the highest. The restriction location of three genes is different from that in typical strains, such as HD-1 and HD-73 strains. 4190 bp nucleotide sequence of cry218 gene was determined and this gene was named cry1Ac10 in the recently published gene nomenclature.

Bacillus thuringiensis↗
PubMed2000

[A new resolution vector with cry1Ac10 gene based on Bacillus thuringiensis transposon Tn4430].

A new resolution vector with cry1Ac10 gene based on TnpI-mediated site-specific recombination system of Bacillus thuringiensis(Bt) transposon Tn4430 was developed. The gene cry1Ac10, encoding a protoxin against plutella xylostella larvae, and the gene ori1030, from a plasmid of wide type Bacillus thuringiensis, were inserted into two copy sets of RES sites, named pBMB801. When pBMB801 was introduced into crystal negative Bt host BMB171, antibiotic resistance genes and other non-Bt DNA can be selectively eliminated. This recombinant plasmid was found very stable without antibiotic selection. The resulting strain only contained Bt DNA and is free of antibiotic resistance genes. This strategy should facilitate regulatory approval for its development as a commercial biopesticide.

Bacillus thuringiensis↗
PubMed2000

[The application of epiglottis in laryngeal function reconstruction after partial laryngectomy].

OBJECTIVE: To observe the appliance value of epiglottis in laryngeal function reconstruction after partial laryngectomy. METHODS: Thirty-two cases of glottic and superglottic carcinomas of larynx had conducted partial laryngectomy and the laryngeal function was reconstructed using epiglottis from December. 1992 to January 1996. RESULTS: Nineteen of the twenty-one glottic carcinomas and five of eleven supraglottic carcinomas were decannulated and recovered with laryngeal functions. All the patients rehabilitated deglutition in 14-18 days after surgery. None presented complication of aspiration. CONCLUSIONS: Epiglottis has many advantages in partial laryngectomy and the laryngeal reconstruction. It is easy to approach, apply and heal in short period. It also prevents aspiration and improves the decannulation rate as well as the quality of life in partial laryngectomy patients.

Adult↗
PubMed2000

Conservative management of twin pregnancy with single fetal death.

OBJECTIVE: Analysis of the cause of intrauterine death of one fetus of twin and to evaluate the outcome of conservative management of twin pregnancy with single fetal death. METHOD: A retrospective review was undertaken on PUMC hospital records of women who delivered twin between Jan. 1987 and Dec. 1998. RESULT: During the recent 12 years, 99 pregnant women were documented as twin pregnancies. Of the twin pregnancies during this period, 13 were complicated by a single intrauterine death. Four women suffered this complication during their first trimester. In the remain 9 cases one fetus died during second or third trimester. The cesarean section was given in three pregnant women soon after a single intrauterine death because of the survival fetal distress. No consumptive coagulopathy was apparent in all 13 pregnant women. It is wise that the pregnancy was managed conservatively, with regular coagulation parameters obtained. CONCLUSION: Our results support conservative management in twin pregnancies complicated by single fetal death.

Adult↗
PubMed2000

[Spectrophotometric determination of trace cadmium in polyferric sulphate flocculent].

A new sensitive method for determining trace cadmium in polyferric sulphate flocculent is proposed in the paper. The new sensitive method is spectrophotometric method. The color reagents are the butylrhodamin B and potassium iodide. The surfactant is the polyvingl alcohol(PVA). The maximum absorbency wavelength is 607 nm. The molar absorptivity is 4.99 x 10(5) L.mol-1.cm-1. The sandell sensitivity is 2.25 x 10(-4) micrograms Cd2+.cm-2. The Beer's law is obeyed for Cd(II) in the range of 0-1.5 micrograms.25 mL-1. The recovery is 96%-105% and the sample processing procedure is simple. This method has been applied to determination of trace Cd(II) in polyferric sulphate flocculent. The determining results are satisfactory.

Cadmium↗
PubMed1999

HCPTPA, a protein tyrosine phosphatase that regulates vascular endothelial growth factor receptor-mediated signal transduction and biological activity.

Angiogenesis is a tightly controlled process in which signaling by the receptors for vascular endothelial growth factor (VEGF) plays a key role. In order to define signaling pathways downstream of VEGF receptors (VEGFR), the kinase domain of VEGFR2 (Flk-1) was used as a bait to screen a human fetal heart library in the yeast two-hybrid system. One of the signaling molecules identified in this effort was HCPTPA, a low molecular weight, cytoplasmic protein tyrosine phosphatase. Although HCPTPA possesses no identifiable phosphotyrosine binding domains (i.e. SH2 or phosphotyrosine binding domains), it bound specifically to active, autophosphorylated VEGFR2 but not to a mutated, kinase-inactive VEGFR2. Recombinant VEGFR2 and endogenous VEGFR2 were substrates for recombinant HCPTPA, and HCPTPA was co-expressed with VEGFR2 in endothelial cell lines, suggesting that HCPTPA may be a negative regulator of VEGFR2 signal transduction. To pursue this possibility, an adenovirus directing the expression of HCPTPA was constructed. When used to infect cultured endothelial cells, this adenovirus directed high level expression of HCPTPA that resulted in impairment of VEGF-mediated VEGFR2 autophosphorylation and mitogen-activated protein kinase activation. Adenovirus-mediated overexpression of HCPTPA also inhibited VEGF-induced cellular responses (endothelial cell migration and proliferation) and inhibited angiogenesis in the rat aortic ring assay. Taken together, these findings indicate that HCPTPA may be an important regulator of VEGF-mediated signaling and biological activity. Potential interactions with other signaling pathways and possible therapeutic implications are discussed.

Animals↗
PubMed1999

Lack of the p50 subunit of nuclear factor-kappaB increases the vulnerability of hippocampal neurons to excitotoxic injury.

Nuclear factor-kappaB (NF-kappaB) is activated in brain cells after various insults, including cerebral ischemia and epileptic seizures. Although cell culture studies have suggested that the activation of NF-kappaB can prevent neuronal apoptosis, the role of this transcription factor in neuronal injury in vivo is unclear, and the specific kappaB subunits involved are unknown. We now report that mice lacking the p50 subunit of NF-kappaB exhibit increased damage to hippocampal pyramidal neurons after administration of the excitotoxin kainate. Gel-shift analyses showed that p50 is required for the majority of kappaB DNA-binding activity in hippocampus. Intraventricular administration of kappaB decoy DNA before kainate administration in wild-type mice resulted in an enhancement of damage to hippocampal pyramidal neurons, indicating that reduced NF-kappaB activity was sufficient to account for the enhanced excitotoxic neuronal injury in p50(-/-) mice. Cultured hippocampal neurons from p50(-/-) mice exhibited enhanced elevations of intracellular calcium levels and increased levels of oxidative stress after exposure to glutamate and were more vulnerable to excitotoxicity than were neurons from p50(+/+) and p50(+/-) mice. Collectively, our data demonstrate an important role for the p50 subunit of NF-kappaB in protecting neurons against excitotoxic cell death.

Animals↗
PubMed1999

Targeted cytoplasmic irradiation with alpha particles induces mutations in mammalian cells.

Ever since x-rays were shown to induce mutation in Drosophila more than 70 years ago, prevailing dogma considered the genotoxic effects of ionizing radiation, such as mutations and carcinogenesis, as being due mostly to direct damage to the nucleus. Although there was indication that alpha particle traversal through cellular cytoplasm was innocuous, the full impact remained unknown. The availability of the microbeam at the Radiological Research Accelerator Facility of Columbia University made it possible to target and irradiate the cytoplasm of individual cells in a highly localized spatial region. By using dual fluorochrome dyes (Hoechst and Nile Red) to locate nucleus and cellular cytoplasm, respectively, thereby avoiding inadvertent traversal of nuclei, we show here that cytoplasmic irradiation is mutagenic at the CD59 (S1) locus of human-hamster hybrid (AL) cells, while inflicting minimal cytotoxicity. The principal class of mutations induced are similar to those of spontaneous origin and are entirely different from those of nuclear irradiation. Furthermore, experiments with radical scavenger and inhibitor of intracellular glutathione indicated that the mutagenicity of cytoplasmic irradiation depends on generation of reactive oxygen species. These findings suggest that cytoplasm is an important target for genotoxic effects of ionizing radiation, particularly radon, the second leading cause of lung cancer in the United States. In addition, cytoplasmic traversal by alpha particles may be more dangerous than nuclear traversal, because the mutagenicity is accomplished by little or no killing of the target cells.

Alpha Particles↗
PubMed1999

Human DNA repair systems: an overview.

DNA repair systems act to maintain genome integrity in the face of replication errors, environmental insults, and the cumulative effects of age. More than 70 human genes directly involved in the five major pathways of DNA repair have been described, including chromosomal location and cDNA sequence. However, a great deal of information as to the precise functions of these genes and their role in human health is still lacking. Hence, we summarize what is known about these genes and their contra part in bacterial, yeast, and rodent systems and discuss their involvement in human disease. While some associations are already well understood, it is clear that additional diseases will be found which are linked to DNA repair defects or deficiencies.

Animals↗
PubMed1999

The endoplasmic reticulum stress-responsive protein GRP78 protects neurons against excitotoxicity and apoptosis: suppression of oxidative stress and stabilization of calcium homeostasis.

The 78-kDa glucose-regulated protein (GRP78) is localized in the endoplasmic reticulum (ER), and its expression is increased by environmental stressors in many types of nonneuronal cells. We report that levels of GRP78 are increased in cultured rat hippocampal neurons exposed to glutamate and oxidative insults (Fe2+ and amyloid beta-peptide) and that treatment of cultures with a GRP78 antisense oligodeoxynucleotide increases neuronal death following exposure to each insult. GRP78 antisense treatment enhanced apoptosis of differentiated PC12 cells following NGF withdrawal or exposure to staurosporine. Pretreatment of hippocampal cells with 2-deoxy-d-glucose, a potent inducer of GRP78 expression, protected neurons against excitotoxic and oxidative injury. GRP78 expression may function to suppress oxidative stress and stabilize calcium homeostasis because treatment with GRP78 antisense resulted in increased levels of reactive oxygen species and intracellular calcium following exposure to glutamate and oxidative insults in hippocampal neurons. Dantrolene (a blocker of ER calcium release), uric acid (an antioxidant), and zVAD-fmk (a caspase inhibitor) each protected neurons against the death-enhancing action of GRP78 antisense. The data suggest that ER stress plays a role in neuronal cell death induced by an array of insults and that GRP78 serves a neuroprotective function.

Animals↗
PubMed1999

Changes in blood pressure, body mass index, and salt consumption in a Chinese population.

BACKGROUND: The prevalence of hypertension among the population of Tianjin is one of the highest in China. We attempted to assess the changes in blood pressure, body mass index, and salt consumption in Tianjin from 1989 to 1996. METHODS: Two independent cross-sectional population surveys with the representative samples of 14,046 persons in 1989 and 2,000 persons in 1996 were carried out in Tianjin. A salt surveillance system was established with four salt consumption surveys (in 1992, 1993, 1994, and 1996) to estimate the changes in salt consumption at the household level. RESULTS: From 1989 to 1996, the prevalence of hypertension and obesity decreased among people aged 45-64 years in both genders. Mean systolic blood pressure decreased significantly in women and leveled off in men. Diastolic blood pressure increased significantly. Body mass index remained unchanged. The unfavorable trends were mainly attributable to the negative changes in younger people (15-34 years) in both genders. There were no changes in salt consumption between 1992 and 1996 at the house level. CONCLUSIONS: There was a favorable development in prevalence of hypertension and obesity among individuals in the age group of 45-64 years in the study population. Health education needs to pay more attention to young people.

Adolescent↗
PubMed1999

Recent advances in understanding resin acid biodegradation: microbial diversity and metabolism.

Resin acids are tricyclic diterpenoids that are found in the oleoresin of coniferous trees. Resin-acid-degrading microorganisms are ubiquitous in the environment. The bacterial isolates that grow on resin acids as sole organic substrates are physiologically and phylogenetically diverse, and include psychrotolerant, mesophilic, and thermophilic bacteria. Recent studies of the biodegradation of resin acids by these organisms have demonstrated that in gram-negative bacteria, distinct biochemical pathways exist for the degradation of abietane- and pimerane-type resin acids. One of these organisms, Pseudomonas abietaniphila BKME-9, harbors a convergent pathway that channels the nonaromatic abietanes and dehydroabietic acid into 7-oxodehydroabietic acid. This dioxygenolytic pathway is encoded by the recently cloned and sequenced dit gene cluster. The dit cluster encodes the ferredoxin and the alpha- and beta-subunits of a new class of ring-hydroxylating dioxygenases as well as an extradiol ring-cleavage dioxygenase. Although it was previously thought that resin acids are very recalcitrant under anoxic conditions, recent investigations have demonstrated that they are partially metabolized under anoxic conditions by undefined microorganisms. The anaerobic degradation of resin acids principally generates aromatized and decarboxylated products (such as retene) that are thought to persist in the environment.

Bacteria, Aerobic↗
PubMed1999

Occurrence of Two Resin Acid-Degrading Bacteria and a Gene Encoding Resin Acid Biodegradation in Pulp and Paper Mill Effluent Biotreatment Systems Assayed by PCR.

> Abstract We examined the distribution of two dehydroabietic acid-degrading bacteria, Pseudomonas abietaniphila BKME-9 and Zoogloea resiniphila DhA-35, in biotreatment systems for pulp and paper mill effluents (PPMEs) using PCR assays. These two bacteria were first isolated from two PPME biotreatment systems and can degrade both dehydroabietic acid (DhA) and other abietane resin acids. We also examined the distribution of a catabolic gene, ditA1, encoding the alpha subunit of an aromatic ring-hydroxylating dioxygenase involved in DhA degradation by BKME-9. PCR primers specific for the 16S rDNA of BKME-9 and of DhA-35 and specific for ditA1 were used. Among 3 laboratory- and 17 full-scale PPME biotreatment systems, 10 contained phylotype BKME-9, 3 contained phylotype DhA-35, and 11 contained ditA1, indicating the wider distribution of phylotype BKME-9 than of phylotype DhA-35. Both phylotype BKME-9 and ditA1 were detected in the biotreatment system from which BKME-9 was originally isolated in 1994, suggesting the persistance of BKME-9 in that biotreatment system. The detection limit of the PCR assay was one cell per PCR reaction, which corresponds to one BKME-9 cell per 6 x 10(7) total sludge bacteria. A competitive PCR assay indicated that ditA1 ranged from 51 to 250 copies/mg of dry biomass. BKME-9 appears to contribute to the biodegration of resin acids in some PPME biotreatment systems. Using degenerate PCR primers and touchdown PCR, we obtained from our DhA-degrading strain collection six DNA sequences putatively homologous to that of ditA1. Cluster analysis of these DNA sequences suggests that ditA1 encodes a representative of a novel class of dioxygenase enzymes.http://link.springer-ny.com/link/service/journals/00248/bibs/38n2p114.html

Journal Article↗
PubMed1999

Formation of single- and double-strand breaks of pBR322 plasmid irradiated in the presence of scavengers.

By the method of gel electrophoresis, radiation-induced DNA single- and double-strand breaks (SSB, DSB) were studied with a model system of pBR322 solution in vitro in the presence of 'OH radical scavengers, mannitol and TE (10(-2) mol dm(-3) Tris and 10(-3) mol dm(-3) ethylene diamine tetra-acetic acid). Experiments showed that SSB resulted from one-hit events of radiation energy deposition and DSB resulted from both one-hit and two-hit energy deposition events and so were distinguished into two classes of alphaDSB and betaDSB. Moreover, alpha/beta, where alpha is the number of DSB per unit dose induced in one irradiation event and beta the number of DSB per unit squared dose induced by the combination of two independent SSB, was related to the scavenging capacity, sigma, and for sigma > 10(8) s(-1), alphaDSB predominate over DSB. On the other hand, if sigma<2x10(8)s(-1), the measured G(alphaDSB) decreased in parallel with G(SSB), i.e., G(alphaDSB)/G(SSB) was a constant. When sigma>2x10(8) s(-1). G(alphaDSB) decreased slightly so that the ratio of alphaDSB to SSB evidently increased. Therefore, alphaDSB could be induced by the radical transfer mechanism for sigma<2x10(8) s(-1) and contrarily produced by the local multiply damaged sites (LMDS) mechanism for sigma larger than this value. In addition, the distance for two independent complementary SSB forming a DSB was deduced, but no apparent variation of it was found in the wide sigma range from approximately 10(5) to approximately 10(9) s(-)1, which shows that the DNA steric structure was not influenced by mannitol.

DNA Damage↗
PubMed1999

Glomerulonephritis in a neonate with atypical congenital lupus and toxoplasmosis.

The development of glomerulonephritis as a complication of neonatal lupus or congenital toxoplasmosis is extremely rare. We report a case of membranous glomerulonephritis occurring in a neonate with toxoplasmosis and atypical congenital lupus, including high-titer antinuclear antibodies and hypocomplementemia. This case illustrates that glomerulonephritis in the neonate may be induced by passively transferred maternal antibodies.

Basement Membrane↗
PubMed1999

High-performance liquid chromatography study of the pharmacokinetics of various spin traps for application to in vivo spin trapping.

In vivo spin trapping is potentially a very useful tool to investigate the role of free radicals in physiologic processes and disease development. Unfortunately, knowledge on the stability and distribution of spin traps in living systems is limited. Therefore, in our study, we selected 11 acyclic and cyclic nitrone spin traps with diverse properties to determine their pharmacokinetics in mice. At varying times after intraperitoneal administration, we measured the concentration of the spin traps in the liver, heart, and blood. Our results showed that most spin traps were rapidly absorbed and were approximately evenly distributed throughout the mouse body. It was also found that most of the traps were relatively stable in vivo with more than half of the injected amount still available for spin trapping free radicals after an hour. Two of the 11 tested spin traps, however, decomposed after injection. These results indicate that for a successful in vivo spin trapping experiment, the stability of the spin trap is not of major concern, but the time course of distribution may be important.

Animals↗