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Biomedical subjects

X Zhou

Publications and source records attributed to X Zhou.

At least 307 records · Page 17Linked to original sources
PubMed2000

[Transfer of two large linear plasmids pHZ1000 and pHZ1001 by conjugation from Streptomyces T8-4 to S. lividans ZX1].

Using pulsed-field gel electrophoresis (PFGE), two indigenous large plasmids were isolated from Streptomyces T8-4. Two dimentional PFGE revealed that both plasmids were linear molecules. By parallel electrophoresis with linear plasmids of known sizes, the two linear plasmids were estimated to be approximately 230 kb and 90 kb, which were designated as pHZ1000 and pHZ1001, respectively. Both plasmids could be transferred into S. lividans ZX1 by conjugation, which is detectable by "pock" formation. Five S. lividans ZX1 derivatives which carry one or two plasmids were isolated and characterized by Southern hybridization and PFGE.

Conjugation, Genetic↗
PubMed2000

[Fuzzy space based segmentation algorithm on periosteum medical image processing].

Object description in medical image often has the property of fuzziness, and with the development of computing, fuzzy logical theories are progressively used in medical image processing. Color medical images differ in spacial presentation and fuzzy description from grey-scale images and must be analyzed by special methods. In this paper, a new method of bone cell segmentation based on fuzzy logical theories is presented. With the utilization of fuzzy set theories in the steps of color enhancing, feature extraction and automatical segmentation, bone cells are detected from the background. The method has the advantages of high accuracy and flexibility to many situations. Experiments of bone cell images have proved that it is a fast and effective method.

Algorithms↗
PubMed2000

[The descriptions identification of "yimu cao"].

Remained but entire bracts beneath the inflorescence and the persistent calyxes were selected as primary characteristics to distinguish "Yimu Cao", which derived from 8 species and 1 variety in the same genus Leonurus. The results were reliable.

Flowers↗
PubMed2000

[Effect of raw radish on pharmacological action of ginseng].

Ginseng decoction can increase the memory-improvement, weary-resistance, antihypoxia, sedation in mice, and increase the weight of spleen and accessory sexual gland, but reduce the weight of thymus. Raw radish can decrease these pharmacological effects in varying degrees, except the sedation.

Animals↗
PubMed2000

[Effects of 1 alpha(OH)D3 on trabecular and cortical bone in ovariectomized rats].

OBJECTIVE: To study the pharmaceutical effects of 1 alpha(OH)D3 on trabecular and cortical bone in ovariectomized (OVX) rats. METHODS: 41 female Wistar rats of six months old were randomly divided into 5 groups: (1) Baseline control; (2) Sham control; (3) 6 weeks after OVX (OVXb); (4) 14 weeks after OVX (OVXe); (5) OVX + 0.1 microgram/(kg.d) 1 alpha(OH)D3 (O + VD), treatment started 6 weeks after OVX and lasted 8 weeks. Histomorphometry analysis of tibia, peripheral quantitative computed tomography (pQCT) scanning of femur, bone biomechanical test and serum and urinary biochemical parameters were determined. RESULTS: The levels of bone turnover indexes increased in OVX rats, OVX also resulted in reducing of trabecular, bone mass and biomechanical properties. The ratio of urinary deoxypyridinoline crosslink/creatinine was decreased by 67.0% in O + VD group compared with OVXe group 67.0% [(43.50 +/- 11.20) nmol.L-1/mmol.L-1 vs(131.80 +/- 14.90) nmol.L-1/mmol.L-1, P < 0.01]. Percent trabecular area (Cn-BV/TV) was increased by 89.8% in O + VD group compared with OVXe group (11.03 +/- 0.73 vs 5.81 +/- 1.29, P < 0.05). Trabecular bone mineral content and density were increased by 77.3% and 91.3% compared with OVXe respectively (P < 0.05). Although cancellous maximal load and stiffness increased in O + VD group, but no statistical significance. 1 alpha(OH)D3 also enhanced polar moment of inertia (PMI) and maximal load of cortical bone in femur compared with OVXe (23.70 +/- 1.63 vs 18.23 +/- 1.41, P < 0.01 and 171.69 +/- 9.92 vs 147.58 +/- 11.29, P < 0.05 respectively). CONCLUSION: 1 alpha(OH)D3 inhibited the higher bone turnover induced by OVX, increased trabecular bone in proximal tibia and bone mass in distal femur. 1 alpha(OH)D3 also improved the mechanical properties of cortical bone in femur.

Animals↗
PubMed2000

[FT-Raman spectroscopic investigation on stomach cancer].

FT-Raman spectroscopy was used to investigate 40 normal and malignant tissues from stomach. Statistic analysis shows that the bands related to OH, NH, C=O stretching and H-O-H bending are stronger in malignant tissues. This phenomenon suggests that the hydrogen bonding systems among water and protein vary in malignant tissues.

Humans↗
PubMed2000

[ICP-AES analysis of trace elements in human hair of chronic hepatitis].

The concentration of Al, Ba, Ca, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, Zn and other trace elements in human hair of chronic hepatitis(college students) were determined by ICP-AES. RSD of the method was 1.4%-4.9%, recovery was 94%-129%. Analysis results were compared with that of healthy. There are remarkable differences between concentration of Al, Cu, Fe, Ni, Zn and Mn. Correlation between trace elements and chronic hepatitis were also discussed.

Aluminum↗
PubMed1999

Case study of the effects of atmospheric aerosols and regional haze on agriculture: an opportunity to enhance crop yields in China through emission controls?

The effect of atmospheric aerosols and regional haze from air pollution on the yields of rice and winter wheat grown in China is assessed. The assessment is based on estimates of aerosol optical depths over China, the effect of these optical depths on the solar irradiance reaching the earth's surface, and the response of rice and winter wheat grown in Nanjing to the change in solar irradiance. Two sets of aerosol optical depths are presented: one based on a coupled, regional climate/air quality model simulation and the other inferred from solar radiation measurements made over a 12-year period at meteorological stations in China. The model-estimated optical depths are significantly smaller than those derived from observations, perhaps because of errors in one or both sets of optical depths or because the data from the meteorological stations has been affected by local pollution. Radiative transfer calculations using the smaller, model-estimated aerosol optical depths indicate that the so-called "direct effect" of regional haze results in an approximately 5-30% reduction in the solar irradiance reaching some of China's most productive agricultural regions. Crop-response model simulations suggest an approximately 1:1 relationship between a percentage increase (decrease) in total surface solar irradiance and a percentage increase (decrease) in the yields of rice and wheat. Collectively, these calculations suggest that regional haze in China is currently depressing optimal yields of approximately 70% of the crops grown in China by at least 5-30%. Reducing the severity of regional haze in China through air pollution control could potentially result in a significant increase in crop yields and help the nation meet its growing food demands in the coming decades.

Agriculture↗
PubMed1999

Humoral response to herpes simplex virus is complement-dependent.

The complement system represents a cascade of serum proteins, which provide a major effector function in innate immunity. Recent studies have revealed that complement links innate and adaptive immunity via complement receptors CD21/CD35 in that it enhances the B cell memory response to noninfectious protein antigens introduced i.v. To examine the importance of complement for immune responses to virus infection in a peripheral tissue, we compared the B cell memory response of mice deficient in complement C3, C4, or CD21/CD35 with wild-type controls. We found that the deficient mice failed to generate a normal memory response, which is characterized by a reduction in IgG antibody and germinal centers. Thus, complement is important not only in the effector function of innate immunity but also in the stimulation of memory B cell responses to viral-infected cell antigens in both blood and peripheral tissues.

Animals↗
PubMed1999

Loss of Fhit is frequent in stage I non-small cell lung cancer and in the lungs of chronic smokers.

Abnormalities of FHIT, a candidate tumor suppressor gene at 3p14.2, have been found frequently in multiple tumor types including non-small cell lung cancer (NSCLC). To investigate whether FHIT inactivation plays a role in early lung tumorigenesis, Fhit levels were determined by immunohistochemistry in tumors from 87 patients with stage I NSCLC and in 372 bronchial biopsy specimens from 86 chronic smokers without evidence of malignancy. We found that 49% of NSCLC specimens demonstrated significantly decreased staining or lack of staining for Fhit. However, Fhit expression status was not significantly associated with disease-free survival or overall survival. Analysis of a subset of 76 specimens on which microsatellite analysis at the FHIT locus was performed did not show a strong association between loss of heterozygosity at FHIT and Fhit expression, suggesting the presence of complex mechanisms of Fhit inactivation. Of 372 bronchial biopsies from chronic smokers, 86 biopsies (23%) exhibited decreased Fhit expression or lack of Fhit expression. In 37 of 86 (43%) subjects, decreased Fhit expression or lack of expression was observed in at least one biopsy site. Loss of Fhit expression was significantly higher in bronchial metaplastic lesions (23 of 49 lesions, 47%) than in histologically normal bronchial epithelium (63 of 323 specimens, 20%; P < 0.001). Smokers with a metaplasia index of > 15% had a higher frequency of loss of Fhit expression than those with a metaplasia index of < or = 15% (P = 0.015). Interestingly, current smokers had a higher rate of loss of Fhit expression than former smokers (P = 0.02). Our data indicate that Fhit expression is significantly reduced in a substantial number of early-stage NSCLC and preneoplastic lesions in chronic smokers. The association between cigarette smoking and Fhit expression suggests a role for FHIT in the initiation of smoking-related lung tumorigenesis.

Acid Anhydride Hydrolases↗
PubMed1999

Endothelial vasodilator function is preserved at the spastic/inflammatory coronary lesions in pigs.

BACKGROUND: The question of whether or not endothelial vasodilator function in the spastic coronary artery is preserved is still controversial. We recently developed a porcine model in which long-term and local treatment with interleukin-1beta (IL-1beta) from the adventitial site causes coronary arteriosclerotic changes and vasospastic responses to autacoids. The aim of this study was to examine the endothelial vasodilator function in our new porcine model of the spasm both in vivo and in vitro. METHODS AND RESULTS: A segment of the porcine coronary artery was aseptically wrapped with cotton mesh that held absorbed IL-1beta-bound microbeads. Two weeks after the procedure, intracoronary administration of serotonin caused coronary vasospasm at the IL-1beta-treated site (n = 10). Coronary vasodilatation to bradykinin, substance P, or an increase in coronary blood flow was preserved at the spastic site. Vasodilator responses to 3-morpholinosydnonimine (an NO donor) and nitroglycerin also were comparable between the 2 sites. The vasoconstricting response to N(G)-monomethyl-L-arginine and the extent of the augmentation of the serotonin-induced vasoconstriction were comparable between the 2 sites. Organ chamber experiments showed that endothelium-dependent relaxations to bradykinin, the calcium ionophore A23187, and even the vasospastic agonist serotonin were preserved at the spastic site, whereas contractions to serotonin were augmented at the spastic site regardless of the presence or absence of the endothelium (n = 6). Endothelium-independent relaxations to sodium nitroprusside were also preserved at the spastic site. CONCLUSIONS: These results indicate that endothelial vasodilator function is preserved at the spastic site and that the spasm is caused primarily by smooth muscle hypercontraction in our porcine model.

Animals↗
PubMed1999

Axotomy-induced changes in pituitary adenylate cyclase activating polypeptide (PACAP) and PACAP receptor gene expression in the adult rat facial motor nucleus.

It has been demonstrated that pituitary adenylate cyclase activating polypeptide (PACAP) promotes the survival of neurons in culture and can inhibit neuronal cell death after experimental injury. Furthermore, peripheral axotomy results in increased PACAP gene expression in sensory and sympathetic neurons, suggesting that PACAP might be a mediator in the injury response in certain parts of the nervous system. However, changes in PACAP expression have not been reported in injured motor neurons, despite the significant problem of motor neuron degeneration in injury and in several neurological diseases. We examined here changes in gene expression of PACAP and two high-affinity PACAP receptors, PAC(1) and VPAC(2), in adult rat motor neurons after facial nerve axotomy by in situ hybridization. PACAP gene expression was very low in facial motor neurons of normal rats. However, a robust time-dependent increase in PACAP mRNA was observed in the facial motor nucleus in most or all axotomized motor neurons. This induction was detectable 6 hr after axotomy, and peaked at 48 hr, when expression on the injured side averaged more than 20-fold higher than that on the contralateral side. Thereafter, PACAP mRNA levels decreased slightly, but remained more than 10-fold elevated for as long as 30 days after axotomy. In contrast to PACAP, gene expression for both the PAC(1) and VPAC(2) receptor was high in facial motor neurons of normal rats. No significant change was observed for VPAC(2) receptor gene expression in facial motor neurons after axotomy, whereas gene expression for the PAC(1) receptor became significantly decreased. The results indicate that the PACAP ligand receptor system is tightly regulated in the facial motor nucleus after axotomy, providing evidence that PACAP may be involved in motor injury responses.

Animals↗
PubMed1999

Protein kinase A is a negative regulator of renal branching morphogenesis and modulates inhibitory and stimulatory bone morphogenetic proteins.

Protein kinase A (PKA) regulates morphogenetic responses to bone morphogenetic proteins (BMPs) during embryogenesis. However, the mechanisms by which PKA regulates BMP function are unknown. During kidney development, BMP-2 and high doses of BMP-7 inhibit branching morphogenesis, whereas low doses of BMP-7 are stimulatory (Piscione, T. D., Yager, T. D., Gupta, I. R., Grinfeld, B., Pei, Y., Attisano, L., Wrana, J. L., and Rosenblum, N. D. (1997) Am. J. Physiol. 273, F961-F975). We examined the interactions between PKA and these BMPs in embryonic kidney explants and in the mouse inner medullary collecting duct-3 model of collecting duct morphogenesis. H-89, an inhibitor of PKA, stimulated branching morphogenesis and enhanced the stimulatory effect of low doses of BMP-7 on tubule formation. Furthermore, H-89 rescued the inhibition of tubulogenesis by BMP-2 (or high doses of BMP-7) by attenuating BMP-2-induced collecting duct apoptosis. In contrast, 8-bromo-cAMP, an activator of PKA, inhibited tubule formation and attenuated the stimulatory effects of low doses of BMP-7. To determine mechanisms underlying the interdependence of BMP signaling and PKA activity, we examined the effect of PKA on the known signaling events in the BMP-2-dependent Smad1 signaling pathway and the effect of BMP-2 on PKA activity. PKA did not induce endogenous Smad1 phosphorylation, Smad1-Smad4 complex formation, or Smad1 nuclear translocation. In contrast, BMP-2 increased endogenous PKA activity and induced phosphorylation of the PKA effector, cAMP-response element-binding protein, in a PKA-dependent manner. We conclude that BMP-2 induces activation of PKA and that PKA regulates the effects of BMPs on collecting duct morphogenesis without activating the known signaling events in the BMP-2-dependent Smad1 signaling pathway.

Animals↗
PubMed1999

Synthesis, biological activity, and conformational analysis of four seco-D-15,19-bisnor-1alpha,25-dihydroxyvitamin D analogues, diastereomeric at C17 and C20.

The synthesis of four CD-ring-modified 19-nor-1alpha, 25-dihydroxyvitamin D(3) derivatives lacking C15, referred to as 6C analogues, and diastereomeric at C17 and C20 is described. The synthesis involves an Ireland-Claisen rearrangement of a 3-methyl-substituted ester of (1R)-3-methyl-2-cyclohexen-1-ol as the key step, followed by elaboration of the side chain, transformation into a C8 cyclohexanone derivative, and final Wittig-Horner coupling with the 19-nor A-ring phosphine oxide. Despite possessing a more flexible side chain than the parent hormone, biological evaluation showed an unexpected superagonistic antiproliferative and prodifferentiating activity (10-50 times higher as compared to that of 1alpha,25(OH)(2)D(3)) for the diastereomer with the "natural" configuration at C17 and C20. The other diastereomers exhibit a 25-90% decrease in activity. All four analogues show a decreased binding affinity (45% or less), and their calcemic activity is 4-400 times less than that of 1alpha,25(OH)(2)D(3). The conformational behavior of their side chain was studied using molecular mechanics calculations, and the result is presented as volume maps. A relative activity volume was determined by subtraction of the volume map of the least active analogue from the volume map of the most active one. This shows three regions corresponding to preferred orientations in space of the side chain of the active analogue. One of these regions was found to overlap with the region that is preferentially occupied by the most active of the four diastereomeric 22-methyl-substituted 1alpha,25(OH)(2)D(3) analogues.

Animals↗
PubMed1999

The in vitro synthesized and processed human insulin receptor precursor binds insulin.

The cell-free examination of the human insulin receptor during biogenesis may provide a greater understanding of the elements that contribute to the acquisition of receptor function. The insulin receptor precursor components were produced in a cell-free system and the insulin binding ability of the [35S]methionine-labeled translation products was determined. The processed proreceptor represented by a 190 kDa band was retained on insulin-linked biotin-streptavidin agarose or an insulin column. The insulin binding 190 kDa band migrated slower than the non-binding 190 kDa band on SDS-PAGE which suggests that covalent modifications account for these differences. The trypsin-digested product of the 190 kDa proreceptor was also retained on insulin-linked biotin-streptavidin agarose, however the alpha-subunit precursor was retained on insulin agarose to a much lesser degree. We conclude that a significant fraction of the processed, in vitro translated insulin proreceptor acquires insulin binding ability.

Animals↗
PubMed1999

The zebrafish genome contains two distinct selenocysteine tRNA[Ser]sec genes.

The zebrafish is widely used as a model system for studying mammalian developmental genetics and more recently, as a model system for carcinogenesis. Since there is mounting evidence that selenium can prevent cancer in mammals, including humans, we characterized the selenocysteine tRNA[Ser]sec gene and its product in zebrafish. Two genes for this tRNA were isolated and sequenced and were found to map at different loci within the zebrafish genome. The encoding sequences of both are identical and their flanking sequences are highly homologous for several hundred bases in both directions. The two genes likely arose from gene duplication which is a common phenomenon among many genes in this species. In addition, zebrafish tRNA[Ser]sec was isolated from the total tRNA population and shown to decode UGA in a ribosomal binding assay.

Animals↗
PubMed1999

Selenium metabolism in Drosophila. Characterization of the selenocysteine tRNA population.

The selenocysteine (Sec) tRNA population in Drosophila melanogaster is aminoacylated with serine, forms selenocysteyl-tRNA, and decodes UGA. The Km of Sec tRNA and serine tRNA for seryl-tRNA synthetase is 6.67 and 9.45 nM, respectively. Two major bands of Sec tRNA were resolved by gel electrophoresis. Both tRNAs were sequenced, and their primary structures were indistinguishable and colinear with that of the corresponding single copy gene. They are 90 nucleotides in length and contain three modified nucleosides, 5-methylcarboxymethyluridine, N6-isopentenyladenosine, and pseudouridine, at positions 34, 37, and 55, respectively. Neither form contains 1-methyladenosine at position 58 or 5-methylcarboxymethyl-2'-O-methyluridine, which are characteristically found in Sec tRNA of higher animals. We conclude that the primary structures of the two bands of Sec tRNA resolved by electrophoresis are indistinguishable by the techniques employed and that Sec tRNAs in Drosophila may exist in different conformational forms. The Sec tRNA gene maps to a single locus on chromosome 2 at position 47E or F. To our knowledge, Drosophila is the lowest eukaryote in which the Sec tRNA population has been characterized to date.

Animals↗