601
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Wallace KK, Zhao B, McArthur HA, Reynolds KA. In vivo analysis of straight-chain and branched-chain fatty acid biosynthesis in three actinomycetes. FEMS Microbiol Lett 1995; 131:227-34. [PMID: 7557334 DOI: 10.1111/j.1574-6968.1995.tb07781.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The starter units for branched-chain and straight-chain fatty acid biosynthesis was investigated in vivo in three actinomycetes using stable isotopes. Branched-chain fatty acids, which constitute the majority of the fatty acid pool, were confirmed to be biosynthesized using the amino acid degradation products methylbutyrl-CoA and isobutyrl-CoA as starter units. Straight-chain fatty acids were shown to be constructed using butyrl-CoA as a starter unit. Isomerization of the valine catabolite isobutyryl-CoA was shown to be only a minor source of this butyryl-CoA.
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602
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Ranganayakulu G, Zhao B, Dokidis A, Molkentin JD, Olson EN, Schulz RA. A series of mutations in the D-MEF2 transcription factor reveal multiple functions in larval and adult myogenesis in Drosophila. Dev Biol 1995; 171:169-81. [PMID: 7556894 DOI: 10.1006/dbio.1995.1269] [Citation(s) in RCA: 172] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The D-mef2 gene encodes a MADS domain transcription factor expressed in differentiated muscles and their precursors in the Drosophila embryo. Embryos deficient for D-MEF2 protein due to a deletion of upstream transcriptional control sequences fail to form muscle, suggesting that the gene is required for muscle cell differentiation. To directly demonstrate a role for D-mef2 in embryonic myogenesis, we isolated gene mutants containing EMS-induced point mutations, characterized the effects of these mutations on D-MEF2 protein stability and nuclear localization, and analyzed the resulting muscle phenotypes. Our results show that in the somatic muscle lineage, D-mef2 is required for both the formation and patterning of body wall muscle. In the absence of somatic myogenesis, there is extensive apoptosis among the myoblast cell population. In contrast, in the cardiac muscle lineage, morphogenesis of the dorsal vessel occurs normally but the three myosin subunit genes are not expressed. Mutant embryos also exhibit an abnormal midgut morphology, which correlates with the absence of alpha PS2 integrin gene expression and muscle-specific enhancer function, suggesting that D-mef2 regulates the inflated locus which encodes this integrin subunit. D-MEF2 is also expressed in adepithelial cells and rare D-mef2 transheterozygous mutant adults fail to fly, consistent with defects observed in the indirect flight muscles. These results demonstrate that the D-mef2 gene has multiple functions in myogenesis and tissue morphogenesis during Drosophila development.
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603
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Hoog SS, Zhao B, Winborne E, Fisher S, Green DW, DesJarlais RL, Newlander KA, Callahan JF, Moore ML, Huffman WF. A check on rational drug design: crystal structure of a complex of human immunodeficiency virus type 1 protease with a novel gamma-turn mimetic inhibitor. J Med Chem 1995; 38:3246-52. [PMID: 7650677 DOI: 10.1021/jm00017a008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have previously reported (Newlander et al., J. Med. Chem. 1993, 36, 2321-2331) the design of human immunodeficiency virus type 1 (HIV-1) protease inhibitors incorporating C7 mimetics that lock three amino acid residues of a peptide sequence into a gamma-turn. The design of one such compound, SB203238, was based on X-ray structures of reduced amide aspartyl protease inhibitors. It incorporates a gamma-turn mimetic in the P2-P1' position, where the carbonyl of the C7 ring is replaced with an sp3 methylene group yielding a constrained reduced amide. It shows competitive inhibition with Ki = 430 nM at pH 6.0. The three-dimensional structure of SB203238 bound to the active site of HIV-1 protease has been determined at 2.3 A resolution by X-ray diffraction and refined to a crystallographic R-factor (R = sigma magnitude of Fo magnitude of - magnitude of Fc magnitude of /sigma magnitude of Fo magnitude of, where Fo and Fc are the observed and calculated structure factor amplitudes, respectively) of 0.177. The inhibitor lies in an extended conformation in the active site; however, because of the constrained geometry of the C7 ring, it maintains fewer hydrogen bonds with the protein than in most other HIV-1 protease-inhibitor complexes. More importantly, the inhibitor binds to the enzyme differently than predicted in its design, by binding with the P2-P1' alpha-carbon atoms shifted by approximately one-half a residue toward the N-terminus from their presumed positions. This study illustrates the importance of structural information in an approach to rational drug design.
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604
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Zhao B, Rickert CH, Filler TJ, Liu B, Verhallen PF, Dierichs R. Adhesion of washed blood platelets in vitro is advanced, accelerated, and enlarged by oxidized low-density lipoprotein. Am J Hematol 1995; 49:177-82. [PMID: 7604810 DOI: 10.1002/ajh.2830490302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In order to study the influence of oxidized low-density lipoprotein (Ox-LDL) on platelet functional morphology at an early activation stage, washed human blood platelets were stimulated by 100 micrograms/ml Ox-LDL at 37 degrees C. The settling and spreading process of stimulated and unstimulated platelets on Formvar-coated glass was observed for approximately 20 min by reflection contrast microscopy (RCM) and quantified by image analysis. Each group consisted of at least 250 platelets. The results show that incubation with Ox-LDL causes platelet shape change and pseudopodia formation. The sedimentation of stimulated platelets precedes that of unstimulated platelets by approximately 3 min. The increase of the total adhesion area of all Ox-LDL treated platelets is significantly accelerated in comparison to normal platelets (20.45 microns2/min vs. 15.45 microns2/min; P < 0.01). The mean total adhesion area of Ox-LDL-treated platelets was generally larger than that of untreated platelets (189.7 microns2 vs. 144.7 microns2; P < 0.01). The disappearance of intracellular granules after platelet activation, observed by RCM, is supported by transmission electron microscopy. Our results suggest that Ox-LDL activates platelets and advances and accelerates their adhesion and thereby may contribute to pathological thrombosis and arteriosclerosis.
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605
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Filler TJ, Rickert CH, Zhao B. Evaluation on blood platelets by the image analysis system VIDAS 2.5. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 1995; 47:177-182. [PMID: 7587164 DOI: 10.1016/0169-2607(95)01649-e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This paper introduces a program written on the image analysis system VIDAS 2.5. It enables the automatic quantification of high numbers of adhesion areas of vital human platelets, thus allowing statistical analysis. These adhesion areas were observed by reflection contrast microscopy (RCM), which generates images of an intense contrast and serves as a prerequisite for an evaluation by image analysis. However, RCM-photographs of the observed platelets have highly varying mean greyvalues and greyranges. These common problems for self-operating identification are excluded by two procedures within the program: 1. calibration of the scanning process for an optimal use of the available greyvalues provided by the negative, camera, and the image analysis system; and 2. relation of the threshold for discrimination of adhesion areas to the statistic parameters of the histogram within each individual digitized image. Images processed according to these prerequisites were transferred to the VIDAS implemented routines for identification and measurement of areas. Thus, image analysis combined with RCM offers a tool for basic and clinical platelet research, which is shown by an example of stimulation and inhibited stimulation of platelet activation.
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606
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Zhao B, Zhang Y, Liu B, Nawroth P, Dierichs R. Endothelial cells injured by oxidized low density lipoprotein. Am J Hematol 1995; 49:250-2. [PMID: 7604820 DOI: 10.1002/ajh.2830490315] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Cultured endothelial cells from bovine aorta were exposed to oxidized low density lipoprotein and examined by electron microscopy. The endothelial cells contracted slightly and the intercellular junctions became unclear. Some osmiophilic material increased in the cytoplasm. The oxidized low density lipoprotein appears to injure endothelial cells and thereby plays a causative role in atherogenesis and thrombogenesis.
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607
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Johanson K, Appelbaum E, Doyle M, Hensley P, Zhao B, Abdel-Meguid SS, Young P, Cook R, Carr S, Matico R. Binding interactions of human interleukin 5 with its receptor alpha subunit. Large scale production, structural, and functional studies of Drosophila-expressed recombinant proteins. J Biol Chem 1995; 270:9459-71. [PMID: 7721873 DOI: 10.1074/jbc.270.16.9459] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Human interleukin 5 (hIL5) and soluble forms of its receptor alpha subunit were expressed in Drosophila cells and purified to homogeneity, allowing a detailed structural and functional analysis. B cell proliferation confirmed that the hIL5 was biologically active. Deglycosylated hIL5 remained active, while similarly deglycosylated receptor alpha subunit lost activity. The crystal structure of the deglycosylated hIL5 was determined to 2.6-A resolution and found to be similar to that of the protein produced in Escherichia coli. Human IL5 was shown by analytical ultracentrifugation to form a 1:1 complex with the soluble domain of the hIL5 receptor alpha subunit (shIL5R alpha). Additionally, the relative abundance of ligand and receptor in the hIL5.shIL5R alpha complex was determined to be 1:1 by both titration calorimetry and SDS-polyacrylamide gel electrophoresis analysis of dissolved cocrystals of the complex. Titration microcalorimetry yielded equilibrium dissociation constants of 3.1 and 2.0 nM, respectively, for the binding of hIL5 to shIL5R alpha and to a chimeric form of the receptor containing shIL5R alpha fused to the immunoglobulin Fc domain (shIL5R alpha-Fc). Analysis of the binding thermodynamics of IL5 and its soluble receptor indicates that conformational changes are coupled to the binding reaction. Kinetic analysis using surface plasmon resonance yielded data consistent with the Kd values from calorimetry and also with the possibility of conformational isomerization in the interaction of hIL5 with the receptor alpha subunit. Using a radioligand binding assay, the affinity of hIL5 with full-length hIL5R alpha in Drosophila membranes was found to be 6 nM, in accord with the affinities measured for the soluble receptor forms. Hence, most of the binding energy of the alpha receptor is supplied by the soluble domain. Taken with other aspects of hIL5 structure and biological activity, the data obtained allow a prediction for how 1:1 stoichiometry and conformational change can lead to the formation of hIL5.receptor alpha beta complex and signal transduction.
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608
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Shi H, Zhao B, Xin W. Scavenging effects of baicalin on free radicals and its protection on erythrocyte membrane from free radical injury. BIOCHEMISTRY AND MOLECULAR BIOLOGY INTERNATIONAL 1995; 35:981-994. [PMID: 7549941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Using electron spin resonance (ESR) spin trapping technique, we found that baicalin (B) could scavenge hydroxyl radicals generated from Fenton reaction. It also could scavenge superoxide radicals generated from the reaction system containing xanthine (X) and xanthine oxidase (XO), as was found by using chemiluminescence (CL) method. Kinetic studies on the competition between baicalin and a spin trap 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) in trapping OH showed that baicalin had a kinetic reactive rate constant of the order of 7.7 x 10(11) M-1 s-1 in its reaction with OH, and the studies on the competition between baicalin and ferricytochrome c (f.c.) in trapping O2- gave a kinetic reactive rate constant of 3.2 x 10(6) M-1 s-1 for baicalin in its reaction with O2-. Furthermore, we have investigated the protective effects of baicalin on erythrocyte membranes from hydroxyl free radical injuries. The results showed that baicalin could reduce hydrogen peroxide-induced hemolysis, protect the conformation of sulfhydryl groups (-SH) on membrane proteins and the membrane fluidity of erythrocytes incubated with hydrogen peroxide. The results indicated that baicalin could protect the membranes of erythrocytes from free radical injuries, and it was even more effective than alpha-tocopherol.
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609
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Ma X, Zhao B, Lin QK. [Investigation on scoliosis incidence among 24,130 school children]. ZHONGHUA LIU XING BING XUE ZA ZHI = ZHONGHUA LIUXINGBINGXUE ZAZHI 1995; 16:109-10. [PMID: 7781047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Through the screening on scoliosis among 24,130 school children in Hu Guan County, Shanxi Province, it showed that the forward-bending test was positive in 1,794 children (7.4 per cent), with male 3.64 per cent and female 3.8 per cent. The hump inclination angles that were more than 4 degrees were found in 665 children (2.75 per cent). The Cobb angles that were more than 10 degrees were found in 347 children. The incidence rate was 1.44 per cent, with a male to female ratio of 1:1.17. Most of them were idiopathic scoliosis.
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610
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Zhao B, Dierichs R, Harrach-Ruprecht B, Winterhorff H. Oxidized LDL induces serotonin release from blood platelets. Am J Hematol 1995; 48:285-7. [PMID: 7717381 DOI: 10.1002/ajh.2830480417] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Oxidized low-density lipoprotein (LDL) induces a release of serotonin from morphologically resting platelets and shape changed platelets. This suggests that oxidized LDL, a newly reported weak agonist, contributes to atherogenesis and thrombogenesis by stimulating platelets.
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611
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Zhao B, Filler TJ, Rickert CH, Dierichs R. Decreased adhesion of oxidized LDL-stimulated platelets caused by cytochalasin D. Cell Tissue Res 1995; 280:183-8. [PMID: 7750132 DOI: 10.1007/bf00304523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The adhesion of human blood platelets is studied with an in vitro model using reflection contrast microscopy and an image analysis system. The adhesive feature is promoted by oxidatively modified low density lipoprotein, which also induces functional morphological changes of platelets. However, when washed platelets are pretreated with 0.05 mM cytochalasin D, oxidized low density lipoprotein (100 micrograms/ml) causes a slower increase of the adhesion area (11.6 microns 2/min) compared to untreated platelets (15.7 microns 2/min) or platelets treated by oxidized low density lipoprotein alone (20.5 microns 2/min, P < 0.01). These results are supported by light transmission analysis and by transmission electron microscopy. Our experiments suggest that cytochalasin D inhibits the change of platelets in shape induced by oxidized low density lipoprotein, hinders the adhesion, but does not prevent the adhesion entirely.
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612
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Kumar AP, Mar PK, Zhao B, Montgomery RL, Kang DC, Butler AP. Regulation of rat ornithine decarboxylase promoter activity by binding of transcription factor Sp1. J Biol Chem 1995; 270:4341-8. [PMID: 7876196 DOI: 10.1074/jbc.270.9.4341] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Ornithine decarboxylase (ODC) is the rate-limiting enzyme of polyamine biosynthesis. We investigated the transcriptional regulation of the rat ODC gene using transient expression assays. The 5'-flanking region (-1156 to +13) of the ODC gene was sufficient to mediate strong basal expression of a luciferase reporter. Sequences between -345 and -93 contributed to basal promoter activity. This region, containing five potential Sp1 binding sites, was analyzed by electrophoretic mobility shift assays. Three specific DNA-protein complexes were identified using H35 nuclear extracts and the -345/-93 ODC probe. Binding to all three was eliminated by competition with an oligonucleotide containing an Sp1 binding site, but not by a mutant Sp1 oligonucleotide. Preincubation with an antibody against Sp1 supershifted complexes associated with one or more of Sp1 binding sites 1-4 as well as with site 5. DNase I footprinting revealed two protected regions: PR-I (-92 to -130) and PR-II (-304 to -332). PR-I contains a putative binding site for Sp1 that was protected by recombinant Sp1 protein. Transfection studies in Schneider SL2 cells demonstrated that the ODC promoter is transactivated up to 350-fold by Sp1 and that this transactivation is dependent on the presence of Sp1 binding sites 1-4. Thus, although the ODC promoter binds multiple nuclear proteins, Sp1 or a related protein appears to be a critical determinant of ODC transcription, possibly through cooperative interactions between Sp1 and additional transcription factors.
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613
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Zhao B, Korfsmeier KH. An unusual anastomosis between the inferior vena cava and left renal vein, causing a spurious venous return. Ann Anat 1995; 177:155-6. [PMID: 7741276 DOI: 10.1016/s0940-9602(11)80065-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In a Caucasian woman, a single vein was found which originated from the inferior vena cava and passed behind the abdominal aorta to join the left ovarian vein just before its entry into the left renal vein. An extra connection therefore existed between the left kidney and the inferior vena cava.
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614
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Lilly B, Zhao B, Ranganayakulu G, Paterson BM, Schulz RA, Olson EN. Requirement of MADS domain transcription factor D-MEF2 for muscle formation in Drosophila. Science 1995; 267:688-93. [PMID: 7839146 DOI: 10.1126/science.7839146] [Citation(s) in RCA: 383] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Members of the myocyte enhancer binding factor-2 (MEF2) family of MADS (MCM1, agamous, deficiens, and serum response factor) box transcription factors are expressed in the skeletal, cardiac, and smooth muscle lineages of vertebrate and Drosophila embryos. These factors bind an adenine-thymidine-rich DNA sequence associated with muscle-specific genes. The function of MEF2 was determined by generating a loss-of-function of the single mef2 gene in Drosophila (D-mef2). In loss-of-function embryos, somatic, cardiac, and visceral muscle cells did not differentiate, but myoblasts were normally specified and positioned. These results demonstrate that different muscle cell types share a common myogenic differentiation program controlled by MEF2.
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615
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Zhao B, Sisodia SS, Kusiak JW. Altered processing of a mutant amyloid precursor protein in neuronal and endothelial cells. J Neurosci Res 1995; 40:261-8. [PMID: 7745619 DOI: 10.1002/jnr.490400215] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Altered proteolysis of the amyloid precursor protein (APP) may play an important role in Alzheimer disease (AD). To better understand the role of mutant APP in the pathogenesis of the disease, we stably overexpressed the mutant APP717F approximately twofold vs. the endogenous wild-type gene in several cell types. The processing of APP was examined by Western blot analysis and immunoprecipitation. We observed distinctive patterns of APP metabolites among various cell lines. Neuronal and endothelial cells expressing mutant APP717F generated higher levels of large, potentially amyloidogenic carboxyl terminal fragments, which were enhanced upon treatment of the cells with leupeptin. These results suggest that mutations in the APP gene shift the protein processing towards the amyloidogenic pathway in neuronal and endothelial cells possibly involving the endosomal-lysosomal system.
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616
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Zhang Y, Song J, Zhao B, Liu H. Crown gall culture and production of tanshinone in Salvia miltiorrhiza. CHINESE JOURNAL OF BIOTECHNOLOGY 1995; 11:137-141. [PMID: 8562850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Crown galls were induced by direct infection of sterile seedlings with Agrobacterium tumefaciens C58, and the transformation was proved by opine identification. The crown galls grew well in a hormone-free medium. B5 and MS basic media were good for the growth of crown galls (strain Ca), which increased up to 102 and 90 times in a month, respectively. However, 67-V and WP basic media are good for tanshinone production. It has been shown that crown galls can be utilized as a culture system to produce secondary metabolites.
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617
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Nordenström J, Elvius M, Bågedahl-Strindlund M, Zhao B, Törring O. Biochemical hyperparathyroidism and bone mineral status in patients treated long-term with lithium. Metabolism 1994; 43:1563-7. [PMID: 7990712 DOI: 10.1016/0026-0495(94)90017-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Lithium is known to interfere with normal calcium homeostasis, but the long-term effects and possible clinical significance are uncertain. Thus, we measured indices of parathyroid function including intact parathyroid hormone (PTH) and ionized and total calcium levels in 26 patients treated for manic-depressive psychosis with lithium for 10 years or longer (mean +/- SD duration, 15 +/- 6 years). Increased ionized calcium levels were found in 11 patients and increased PTH concentrations in five patients. Altogether, 54% of the patients (14 of 26) had ionized calcium and/or PTH levels above the laboratory reference range. The PTH/ionized calcium relationship of the lithium-treated patients was compared with that of a group of normal subjects (n = 23) and with those of three different groups of patients with abnormal parathyroid function (chronic hypoparathyroidism, n = 21; primary hyperparathyroidism [HPT], n = 50; and tertiary HPT, n = 21). Lithium-treated patients had significantly higher ionized calcium levels (P < .0001) but not significantly higher PTH concentrations (P = .08) than the normal subjects. In comparison to the normal controls, lithium-treated patients had a right-sided shift in their PTH/ionized calcium relationship that was in the same direction but less prominent than in primary or tertiary HPT. Dual-energy x-ray absorptiometry disclosed similar bone mineral densities (BMDs) of lithium-treated patients and age-, sex-, and body mass-matched normal controls in the whole body, lumbar spine, and femoral neck (Z scores: +1.20, +1.22, and +1.02, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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618
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Lee EJ, Zhao B, Moochhala SM, Ngoi SS. Frequency of mutant CYPIA1, NAT2 and GSTM1 alleles in a normal Chinese population. PHARMACOGENETICS 1994; 4:355-8. [PMID: 7704042 DOI: 10.1097/00008571-199412000-00009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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619
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Zhao B, Rassendren F, Kaang BK, Furukawa Y, Kubo T, Kandel ER. A new class of noninactivating K+ channels from aplysia capable of contributing to the resting potential and firing patterns of neurons. Neuron 1994; 13:1205-13. [PMID: 7946357 DOI: 10.1016/0896-6273(94)90058-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
From the nervous system of Aplysia, we have cloned a new class of noninactivating K+ channels (aKv5.1) that are activated at low voltage and are capable of contributing to the resting potential and firing patterns of neurons. Expression of aKv5.1 in Aplysia neuron R15 revealed that aKv5.1 exerts an unusual control over cell excitability; it increased the resting potential by more than 20 mV and abolished the spontaneous bursting activity of the cell. In its ability to suppress the endogenous rhythm of R15, aKv5.1 differs in its actions from transient, inactivating K+ channels such as aKv1.1a, an Aplysia homolog of Shaker. aKv1.1a shortens the duration of the spike and increases the afterpotential, but does not suppress bursting. Thus, by expressing different classes of K+ channels, it is possible to redesign, in specific ways, the signaling capabilities of specific, identified neurons.
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620
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Thompson SK, Murthy KH, Zhao B, Winborne E, Green DW, Fisher SM, DesJarlais RL, Tomaszek TA, Meek TD, Gleason JG. Rational design, synthesis, and crystallographic analysis of a hydroxyethylene-based HIV-1 protease inhibitor containing a heterocyclic P1'--P2' amide bond isostere. J Med Chem 1994; 37:3100-7. [PMID: 7932533 DOI: 10.1021/jm00045a015] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The rational design and synthesis of a highly potent inhibitor of HIV-1 protease have been accomplished. The inhibitor, SB 206343, is based on a model derived from the structure of the MVT-101/HIV-1 protease complex and contains a 4(5)-acylimidazole ring as an isosteric replacement for the P1'--P2' amide bond. It is a competitive inhibitor with an apparent inhibition constant of 0.6 nM at pH 6.0. The three-dimensional structure of SB 206343 bound in the active site of HIV-1 protease has been determined at 2.3 A resolution by X-ray diffraction techniques and refined to a crystallographic discrepancy factor, R (= sigma parallel Fo magnitude of/Fc parallel/sigma magnitude of), of 0.194. The inhibitor is held in the enzyme by a set of hydrophobic and polar interactions. N-3 of the imidazole ring participates in a novel hydrogen-bonding interaction with the bound water molecule, demonstrating the effectiveness of the imidazole ring as an isosteric replacement for the P1'--P2' amide bond in hydroxyethylene-based HIV-1 protease inhibitors. Also present are hydrogen-bonding interactions between N-1 of the imidazole ring and the carbonyl of Gly-127 as well as between the imidazole acyl carbonyl oxygen and the amide nitrogen of Asp-129, exemplifying the peptidomimetic nature of the 4(5)-acylimidazole isostere. All of these interactions are in qualitative agreement with those predicted by the model.
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621
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Borzone G, Zhao B, Merola AJ, Berliner L, Clanton TL. Detection of free radicals by electron spin resonance in rat diaphragm after resistive loading. J Appl Physiol (1985) 1994; 77:812-8. [PMID: 8002533 DOI: 10.1152/jappl.1994.77.2.812] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Indirect evidence supports free radical production in the diaphragm under excessive mechanical loads in both in vitro and in situ preparations. We hypothesized that free radicals are produced in the diaphragm with loads in vivo at a sufficient concentration to be detected by electron spin resonance (ESR) spectroscopy. Anesthetized rats underwent severe inspiratory resistive loading for 2.5-3 h with maintenance of blood oxygenation and arterial blood pressure by breathing 70% oxygen. The ESR spectra of four samples (freeze-clamped at liquid nitrogen temperature) from each experimental animal were compared with the spectra from a control animal breathing air and a control animal breathing 70% oxygen. We observed 1) an approximately 30% increase in intensity of free radical signal in experimental animals (n = 10) compared with control animals breathing oxygen (n = 10; P < 0.01) and control animals breathing air (n = 10; P < 0.05), 2) that oxygen alone had no effect on the ESR spectrum, and 3) the intensity of the ESR signal decreased approximately 25% in the experimental group when samples were taken 10 min postmortem, whereas no difference in signal was observed for control animals. We conclude that the diaphragm shows an increased production of free radicals associated with respiratory failure induced by resistive breathing.
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622
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Moya FR, Eguchi H, Zhao B, Furukawa M, Sfeir J, Osorio M, Ogawa Y, Johnston JM. Platelet-activating factor acetylhydrolase in term and preterm human milk: a preliminary report. J Pediatr Gastroenterol Nutr 1994; 19:236-9. [PMID: 7815247 DOI: 10.1097/00005176-199408000-00015] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Human milk may protect against necrotizing enterocolitis (NEC). Since platelet-activating factor (PAF) may participate in the pathophysiology of NEC, we measured PAF acetylhydrolase (PAF-AH), which metabolizes PAF, in term and preterm human milk. The activity of PAF-AH in term milk collected 2-4 days after delivery (n = 17) was 2.7 +/- 1.2 nmol x min-1 x ml-1. A higher activity was found in milk collected at similar times from mothers who delivered between 33 and 36 weeks of gestation (n = 6, 5.6 +/- 2.1 nmol x min-1 x ml-1, p < 0.01). However, milk from mothers who delivered between 26 and 32 weeks of gestation had a PAF-AH activity similar to that of term milk (n = 6, 3.0 +/- 0.7 nmol x min-1 x ml-1). With advancing lactational age, PAF-AH activity in term milk decreased, whereas the activity of this enzyme in preterm milk remained unchanged. In milk samples collected beyond 14 days after delivery from women who gave birth between 33 and 36 weeks or 26 and 32 weeks of gestation, PAF-AH activity was fivefold higher than that found in milk for women delivering at term (3.7 +/- 1.3 and 3.6 +/- 3.6 nmol x min-1 x ml-1 serum 0.7 +/- 0.4 nmol x min-1 x ml-1, respectively, p < 0.05). We speculate that the presence of PAF-AH in human milk may protect against NEC in preterm newborns.
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623
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Zhao B, Dierichs R, Liu B, Holling-Rauss M. Functional morphological alterations of human blood platelets induced by oxidized low density lipoprotein. Thromb Res 1994; 74:293-301. [PMID: 8042196 DOI: 10.1016/0049-3848(94)90117-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effect of oxidized low density lipoprotein (LDL) on the functional morphology of human platelets in vitro was studied by means of transmission electron microscopy. The washed platelets, stimulated by oxidized LDL (50-300 micrograms protein/ml), showed disc-sphere transformation, centralization of granules and complete degranulation in a dose- and time-dependent manner. A cytodamage in platelet membrane was induced by oxidized LDL leading to a lower electron density of cytoplasm compared to control. The morphological observations were supported by an analysis of the platelet shape-change parameter. Since the shape change, induced by oxidized LDL (50 micrograms/ml), was inhibited by a preincubation of platelets with staurosporine (10 nM), the protein kinase C was probably involved in the platelet activation initiated by oxidized LDL. The present results suggest that oxidized LDL could contribute to pathological thrombosis and atherogenesis by activating platelets.
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624
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Saleh AA, Pryde PG, Isada NB, Johnson MP, Evans MI, Sokol RJ, Zhao B, Johnston JM. Platelet activating factor-acetylhydrolase activity following chorionic villus sampling and amniocentesis. JOURNAL OF THE SOCIETY FOR GYNECOLOGIC INVESTIGATION 1994; 1:135-7. [PMID: 9419761 DOI: 10.1177/107155769400100207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Platelet activating factor (PAF) is essential for embryonic development and is a potent vasodilator. It increases vascular permeability and stimulates prostaglandin E2 (PGE2) production. Platelet activating factor-acetylhydrolase (PAF-AH), the enzyme that degrades PAF, is synthesized by decidual macrophages. The aim of this study was to test the hypothesis that chorionic villus sampling (CVS) and/or amniocentesis might cause an increase in maternal PAF-AH activity. METHODS Maternal plasma PAF-AH activity was evaluated before and after genetic amniocentesis (N = 13) and transcervical CVS (N = 29). A control group (N = 9) was evaluated to study the effects of venipuncture. RESULTS Chorionic villus sampling caused a significant elevation in PAF-AH activity (P < .0005). No changes were noted in PAF-AH activity in the amniocentesis or the control group. CONCLUSIONS Chorionic villus sampling causes subclinical release of PAF-AH, possibly from the decidual macrophages. Increased PAF-AH activity might result in decreased PAF levels, which might lead to vasoconstriction in the placental circulation due to lack of the vasodilator effects of PAF and possibly PGE2. This mechanism might explain the increased risk for fetal limb reduction noted with CVS performed at very early gestational ages.
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625
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Li ZX, Zhao B, Feng Z. Brain abscess due to Pasteurella multocida. KANSENSHOGAKU ZASSHI. THE JOURNAL OF THE JAPANESE ASSOCIATION FOR INFECTIOUS DISEASES 1994; 68:403-6. [PMID: 8176282 DOI: 10.11150/kansenshogakuzasshi1970.68.403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The patient was a 26-year-old man who complained of headache and vomiting. On examination, there was nothing abnormal, but the edge of the right optic papilla was not clear. His temperature was 38.5 degrees C, pulse 96/min, blood pressure 120/80 mmHg. A space-occupying lesion in his fronto-dextra cupular part was found by CT scanning. He had a 12-year history of chronic purulent otitis. The diagnosis was a brain abscess in the fronto-dextra cupular part. The brain abscess was extracted and Pasteurella multocida was isolated from the dark brown pus draining from the abscess. The patient recovered through proper antibiotic therapy based on a sensitivity test. Reports of infections caused by this organism in foreign countries very widely from local infections due to bites and scratches by cats, dogs etc. to general infections such as infections of the respiratory tract, sepsis and meningitis. However, Pasteurella multocida brain abscesses are rare. Pasteurella multocida is a Gram-negative short rod which is best known as part of the mouth flora and as a pathogen causing septicemia in many domestic animals, such as cats, dogs etc.. Infection in man results mainly from animal bites or scratches. It has been reported that Pasteurella multodida can cause human septicemia, meningitis, respiratory tract infection, conjunctivitis and other infections. We isolated a strain of Pasteurella multocida from the pus of a brain abscess following chronic purulent otitis on August 6, 1990.
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