901
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Du C, Xu B, Yortsos YC, Chaouche M, Rakotomalala N, Salin D. Correlation of Occupation Profiles in Invasion Percolation. PHYSICAL REVIEW LETTERS 1995; 74:694-697. [PMID: 10058824 DOI: 10.1103/physrevlett.74.694] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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902
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Eriksson S, Xu B, Clayton DA. Properties of mitochondrial DNA metabolising enzymes; implications for chemotherapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995; 370:465-9. [PMID: 7544950 DOI: 10.1007/978-1-4615-2584-4_99] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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903
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Xu B, Clayton DA. A persistent RNA-DNA hybrid is formed during transcription at a phylogenetically conserved mitochondrial DNA sequence. Mol Cell Biol 1995; 15:580-9. [PMID: 7528331 PMCID: PMC232017 DOI: 10.1128/mcb.15.1.580] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Critical features of the mitochondrial leading-strand DNA replication origin are conserved from Saccharomyces cerevisiae to humans. These include a promoter and a downstream GC-rich sequence block (CSBII) that encodes rGs within the primer RNA. During in vitro transcription at yeast mitochondrial replication origins, there is stable and persistent RNA-DNA hybrid formation that begins at the 5' end of the rG region. The short rG-dC sequence is the necessary and sufficient nucleic acid element for establishing stable hybrids, and the presence of rGs within the RNA strand of the RNA-DNA hybrid is required. The efficiency of hybrid formation depends on the length of RNA synthesized 5' to CSBII and the type of RNA polymerase employed. Once made, the RNA strand of an RNA-DNA hybrid can serve as an effective primer for mitochondrial DNA polymerase. These results reveal a new mechanism for persistent RNA-DNA hybrid formation and suggest a step in priming mitochondrial DNA replication that requires both mitochondrial RNA polymerase and an rG-dC sequence-specific event to form an extensive RNA-DNA hybrid.
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904
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Xu B, Ju Z, Hagg U, Tideman H. [Evaluation of presurgical orthodontic correction of the mandibular prognathism]. ZHONGHUA KOU QIANG YI XUE ZA ZHI = ZHONGHUA KOUQIANG YIXUE ZAZHI = CHINESE JOURNAL OF STOMATOLOGY 1995; 30:26-8, 64. [PMID: 7789229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The aim of this study was to evaluate the effects of presurgical orthodontic correction of the mandibular prognathism. The sample consisted of two groups of surgical cases. The cases of the mandibular prognathism in group I with lower anterior dental compensation received presurgical orthodontic decompensation, and the cases in group II without lower anterior dental compensation did not receive presurgical orthodontic decompensation. The results showed that before presurgical orthodontic treatment, significantly differences existed between the two groups variable ILi/OL and ANB. After presurgical orthodontic correction lower incisors position in group I was very close to that in the group II, this means that the presurgical orthodontic treatment significantly changed the position of the lower incisors.
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905
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Li BH, Xu B, Rowland NE, Kalra SP. c-fos expression in the rat brain following central administration of neuropeptide Y and effects of food consumption. Brain Res 1994; 665:277-84. [PMID: 7895063 DOI: 10.1016/0006-8993(94)91348-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Administration of neuropeptide Y (NPY) intracerebroventricularly (i.c.v.) results in the release of a number of hypothalamic and pituitary hormones and stimulation of feeding and suppression of sexual behavior. In this study, we sought to identify cellular sites of NPY action by evaluating perikaryal Fos-like immunoreactivity (FLI), a marker of cellular activation, in those hypothalamic and extrahypothalamic sites previously implicated in the control of neuroendocrine function and feeding behavior. Additionally, we compared the topography of FLI in these brain sites when food was either available ad libitum or withheld after NPY injection (1 nmol/3 microliters, i.c.v.). The results showed that one hour after NPY injection a larger number of cells in the parvocellular region of the paraventricular nucleus (PVN) were FLI-positive in the absence of food consumption. However, in association with food intake, a significant number of cells were intensely stained in the magnocellular region of the PVN. An analogous increase in FLI in association with feeding was apparent in the supraoptic nucleus (SON), the dorsomedial nucleus and the bed nucleus of the stria terminalis in the hypothalamus. Among the extrahypothalamic sites, feeding facilitated FLI in a large number of cells located in the lateral subdivision of the central amygdaloid nucleus and the lateral subdivision of the solitary tract. FLI was observed in a moderate number of cells in the hypothalamic arcuate nucleus (ARC) and ventromedial nucleus, and this response was not changed by feeding.(ABSTRACT TRUNCATED AT 250 WORDS)
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906
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Xu B, Rimpelä A, Järvelin MR, Nieminen M. Sex differences of infant and child mortality in China. SCANDINAVIAN JOURNAL OF SOCIAL MEDICINE 1994; 22:242-8. [PMID: 7716434 DOI: 10.1177/140349489402200402] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The purpose of this paper was to study the sex differences in infant mortality and mortality before the age of 5 in China, and the differences between urban and rural areas on the one hand and urban areas of mainland China and Hong Kong on the other. Published data from the 1982 and 1990 national censuses, the mortality survey of 1976, and UN's publications were used to calculate sex differences and sex ratios of mortality. Infant mortality of both sexes decreased notably from the 1970's onwards, the sex ratios of mortality being 1.15 in 1973-75, 1.06 in 1981 and 0.86 in 1990. A remarkable decline of mortality before the age of 5 was also seen in both sexes, but the sex ratios of mortality were not greatly altered, remaining less than 1 from the 1970's on. In rural areas female infants and young children had a higher mortality compared with males than in urban areas. In Hong Kong, the sex differences of infant and early child mortality were much smaller than in urban areas of mainland China.
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907
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Xu B, Ming NB. Dynamics of light transmission in two-dimensional nonlinear optical superlattices. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1994; 50:5197-5204. [PMID: 9911521 DOI: 10.1103/physreva.50.5197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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908
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Xu B, Hu BP, Ding YM, Huagn W, Zhang L. [Treatment of children recurrent parotitis dominated by immunotherapy]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1994; 3:189-90. [PMID: 15160119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
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909
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Callos JD, DiRado M, Xu B, Behringer FJ, Link BM, Medford JI. The forever young gene encodes an oxidoreductase required for proper development of the Arabidopsis vegetative shoot apex. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1994; 6:835-847. [PMID: 7849756 DOI: 10.1046/j.1365-313x.1994.6060835.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In plant development, leaf primordia are formed on the flanks of the shoot apical meristem in a highly predictable pattern. The cells that give rise to a primordium are sequestered from the apical meristem. Maintenance of the meristem requires that these cells be replaced by the addition of new cells. Despite the central role of these activities in development, the mechanism controlling and coordinating them is poorly understood. These processes have been characterized in the Arabidopsis mutant forever young (fey). The fey mutation results in a disruption of leaf positioning and meristem maintenance. The predicted FEY protein shares significant homology to a nodulin and limited homology to various reductases. It is proposed that FEY plays a role in communication in the shoot apex through the modification of a factor regulating meristem development.
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910
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Xu B, Li H, Webber RH. Malaria in Hubei Province, China: approaching eradication. THE JOURNAL OF TROPICAL MEDICINE AND HYGIENE 1994; 97:277-81. [PMID: 7932923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In the last six years, there has been a steady reduction of Plasmodium vivax malaria in Hubei Province with an API (annual parasite incidence) of 0.134 per thousand by 1992. This is especially so in the south, east, west and north-west parts of the province. Much of this reduction has been produced by a policy of repeated radical treatment in the non-malaria season. In the centre of Hubei, where Anopheles anthropophagus is the chief vector, malaria is still a problem. The key factors in destabilizing malaria are a sudden increase in the number of An. anthropophagus, introduction of non-immunes into the endemic area, and the village doctors' diminished interest in malaria surveillance activities. Impregnated bed nets are possibly the best strategy for reducing malaria, but where the prevalence is reduced to a sufficiently low level efficient case finding and detection are able to contain malaria and produce a continued reduction.
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911
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Abstract
Using the inside-out patch clamp technique, we identified a Cl- channel in patches from the membrane of cultured human hematopoietic myeloblastic leukemia ML-1 cells. The Cl- channel was not seen at negative membrane potentials in excised patches until the membrane potential was depolarized to greater than +40 mV. The channel was also activated by addition of cAMP-dependent protein kinase (PKA) catalytic subunit at physiological membrane potential (-40 mV). Biophysical studies of the Cl- channel revealed that the current-voltage (I-V) relationship of the Cl- channel was outwardly rectifying in symmetrical 142 mM Cl- solutions. Single channel conductances were 48 pS for the outward current measured at +60 mV and 27 pS for the inward current at -60 mV. The open time constant of the channel was dependent on the membrane potential and was significantly prolonged at positive membrane potentials. Channels activated by cAMP-dependent protein kinase spent a significantly longer time in the open state compared to those channels activated by depolarization pulses. Pharmacological properties of the Cl- channel were also studied. Two anion transport inhibitors, anthracene-9-carboxylic acid (9-AC) and 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) caused a flickering block of the channel. Half-inhibitory concentrations (IC50) for 9-AC and DIDS were 174 +/- 20 and 70 +/- 16 microM, respectively. Blockade of the Cl- channel by 9-AC or DIDS was completely reversible. Our findings suggest that outwardly rectifying Cl- channels (ORCC) are present in human hematopoietic myeloblasts. The function of ORCC may be involved in hormone-regulated cell growth, cell volume regulation and immune responses.
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912
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Xu B, Grandér D, Sangfelt O, Einhorn S. Primary leukemia cells resistant to alpha-interferon in vitro are defective in the activation of the DNA-binding factor interferon-stimulated gene factor 3. Blood 1994; 84:1942-9. [PMID: 8080997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Cells from one-third of chronic lymphocytic leukemia (CLL) patients are resistant to alpha-interferon (alpha-IFN) as measured by induction of blast transformation. We have previously shown that all CLL clones express alpha/beta-IFN receptors, but that the resistant cells are defective in the induction of the enzyme 2',5'-oligoadenylate synthetase (2',5-A synthetase). Thus, the deficiency in IFN sensitivity is localized somewhere between the interaction of the IFN molecule with its receptor and induction of 2',5'-A synthetase. We have now further characterized the resistance of CLL clones to IFN by investigating whether it is associated with a defect in the activation of IFN-stimulated gene factor 3 (ISGF3), which is involved in the activation of alpha-IFN-stimulated genes (ISGs). A defect induction of ISGF3 after alpha-IFN treatment was found in 4 of 12 CLL patients. There was a close correlation between defective induction of ISGF3 and a lack of enhancement of 2',5'-A synthetase as well as induction of blast transformation. Pretreatment with gamma-IFN and mixing experiments with extracts from IFN-sensitive cells indicate that a lack of the gamma-component of ISGF3 was the reason for defect in activation in 2 of the patients. We conclude that a defect in activation of ISGF3 is a possible cause for resistance in CLL cells to IFN-induced blast transformation in vitro.
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913
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Xu B, Selsing E. Analysis of sequence transfers resembling gene conversion in a mouse antibody transgene. Science 1994; 265:1590-3. [PMID: 8079173 DOI: 10.1126/science.8079173] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The role of gene conversion in murine immunoglobulin gene diversification is unclear. An antibody gene construct designed to provide the homologous donor and acceptor sequences required for conversion mechanisms was produced and used to generate transgenic mice. When these transgenic mice were immunized, DNA sequence transfers between tandem transgene VDJ regions were detectable and resembled gene conversion events. There is a strong link between these conversion-like sequence transfers and transgene somatic hypermutation, suggesting that both processes might occur at the same stage of B cell differentiation.
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914
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Chia SE, Xu B, Ong CN, Tsakok FM, Lee ST. Effect of cadmium and cigarette smoking on human semen quality. INTERNATIONAL JOURNAL OF FERTILITY AND MENOPAUSAL STUDIES 1994; 39:292-8. [PMID: 7820163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE In recent years, there have been many nonconclusive studies on cigarette smoking and sperm quality. Few studies, if any, have attempted to implicate any decrease of sperm quality. The aim of this study was to examine the relationship between cigarette smoking, blood and seminal plasma concentrations of cadmium and lead, and sperm quality. METHODS A total of 184 males who were undergoing initial screening for infertility were included in the study. Tests conducted included semen characteristics (volume, total sperm count, sperm viability, motility and morphology of spermatozoa), and blood and seminal plasma concentrations of lead and cadmium. RESULTS More than 50% and 70% of the subjects had normal sperm density and motility, respectively. The mean concentrations of lead in blood (PbB) and seminal plasma (PbS) were 7.09 micrograms/dL and 12.98 micrograms/L, respectively, while the mean concentrations of cadmium in blood (CdB) and seminal plasma (CdS) were 0.95 micrograms/L, and 0.58 micrograms/L, respectively. Significant correlations were observed between CdB and cigarette-years and sperm density (negative). CdS was significantly correlated with cigarette-years and sperm volume (negative). Significant trends were observed for different categories of cigarette-years with CdB, CdS and sperm density. CONCLUSION Cigarette smoking appears to affect sperm density, especially in heavy smokers. Cadmium (present) in cigarettes could be a possible causative agent for the low sperm density among smokers.
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915
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Chaouche M, Rakotomalala N, Salin D, Xu B, Yortsos Y. Capillary effects in drainage in heterogeneous porous media: continuum modelling, experiments and pore network simulations. Chem Eng Sci 1994. [DOI: 10.1016/0009-2509(94)e0040-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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916
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Voss-McCowan ME, Xu B, Epstein PN. Insulin synthesis, secretory competence, and glucose utilization are sensitized by transgenic yeast hexokinase. J Biol Chem 1994; 269:15814-8. [PMID: 8195237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Glucokinase regulates insulin secretion by controlling the rate of glucose phosphorylation. In this report we utilize islets transgenic for high affinity yeast hexokinase to examine the role of glucose phosphorylation on other beta cell functions. Normal pancreatic islets responded to culture in low glucose by lowering insulin synthetic rates, becoming depleted of insulin and insulin mRNA, losing competence to respond to glucose with increased insulin secretion, and lowering glucokinase levels by one-half. In transgenic islets, increased high affinity hexokinase activity provided significant protection against reductions in all parameters of insulin synthesis and helped preserve the competence of beta cells to secrete insulin. The transgenic hexokinase also increased the rate of glucose utilization. These results demonstrate that glucose phosphorylation and presumably glucokinase mediate these glucose regulated responses. Of the parameters measured, only the change in glucokinase activity did not show an effect of the yeast hexokinase transgene. We also found that yeast hexokinase transgene expression was regulated 10-fold by glucose. This is the first demonstration of glucose inducibility of the insulin promoter in transgenic mice.
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917
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Voss-McCowan M, Xu B, Epstein P. Insulin synthesis, secretory competence, and glucose utilization are sensitized by transgenic yeast hexokinase. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)40753-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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918
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Dube MG, Xu B, Crowley WR, Kalra PS, Kalra SP. Evidence that neuropeptide Y is a physiological signal for normal food intake. Brain Res 1994; 646:341-4. [PMID: 8069687 DOI: 10.1016/0006-8993(94)90103-1] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Neuropeptide Y is the most potent orexigenic signal known. To test the hypothesis that NPY is a physiological messenger molecule for normal food intake in rats, we studied the effects of passive immunization against endogenous NPY on cumulative daily food intake in non-fasted spontaneously feeding rats. The results show that continuous central infusion of NPY antibodies markedly suppressed the nighttime and the cumulative 24 h food intake in a dose-dependent fashion. These results support the hypothesis that NPY may be a physiological signal involved in the stimulation of ingestive behavior in rats.
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919
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Chaouche M, Rakotomalala N, Salin D, Xu B, Yortsos YC. Invasion percolation in a hydrostatic or permeability gradient: Experiments and simulations. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1994; 49:4133-4139. [PMID: 9961702 DOI: 10.1103/physreve.49.4133] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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920
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Dave KI, Lauriano C, Xu B, Wild JR, Kenerley CM. Expression of organophosphate hydrolase in the filamentous fungus Gliocladium virens. Appl Microbiol Biotechnol 1994; 41:352-8. [PMID: 7764970 DOI: 10.1007/bf00221231] [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: 01/27/2023]
Abstract
The broad-spectrum organophosphate hydrolase (OPH; EC 3.1.8.1) encoded by the organophosphate-degrading gene (opd) from Pseudomonas diminuta MG and Flavobacterium sp. ATCC 27551 possesses capabilities of both P-O bond hydrolysis (e.g. paraoxon) and P-F bond hydrolysis [e.g. sarin and diisopropylfluorophosphate (DFP)]. In the present study a 9.4-kb plasmid, pCL1, was used to transform the saprophytic fungus Gliocladium virens. pCL1 was derived from pJS294 by placing the fungal promoter (prom1) from Cochliobolus heterostrophus upstream and the trpC terminator from Aspergillus nidulans down-stream of the opd gene. Southern analysis of restricted genomic DNA from various transformants indicated that integration occurred non-specifically at multiple sites. Western blot analysis of mycelial extracts from transformants confirmed the production of a processed form of the enzyme in the fungus. Maximal levels of OPH activity (rate of p-nitrophenol production from paraoxon) were observed after 168 h of culture and activity levels correlated with biomass production in mature vegetative growth.
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921
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Hayashi S, Jain S, Chu R, Alvares K, Xu B, Erfurth F, Usuda N, Rao MS, Reddy SK, Noguchi T. Amphibian allantoinase. Molecular cloning, tissue distribution, and functional expression. J Biol Chem 1994; 269:12269-76. [PMID: 8163532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The chain of enzymes necessary to convert uric acid to its metabolic products urea and glyoxylic acid in vertebrates is truncated through the successive loss of allantoicase, allantoinase, and urate oxidase during phylogenetic evolution. Previous studies have assigned the localization of both urate oxidase and allantinase to the peroxisome in the amphibian liver. This study reports the cloning of a cDNA encoding bullfrog (Rana catesbeiana) allantoinase, an enzyme that converts allantoin to allantoic acid. The cDNA is 2112 base pairs in length containing a 1449-base pair open reading frame which corresponds to a 483-residue protein (53,296 Da). Structural analysis of the deduced protein suggested two potential transmembrane segments and the presence of a putative mitochondrial localization sequence in the amino terminus. Immunocytochemical analysis revealed that allantoinase is localized to mitochondria and not to peroxisomes. On Northern blotting, a single mRNA species was detected in the liver and kidney of frog but not in other tissues; this distribution was confirmed by immunoblotting. The hepatic- and renal-specific expression of allantoinase coincides with the distribution of urate oxidase in these tissues in the frog. The allantoinase expressed in Saccharomyces cerevisiae and in Spodoptera frugiperda (Sf9) insect cells exhibits catalytic activity and is antigenically identical to the native frog enzyme.
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922
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Hayashi S, Jain S, Chu R, Alvares K, Xu B, Erfurth F, Usuda N, Rao M, Reddy S, Noguchi T. Amphibian allantoinase. Molecular cloning, tissue distribution, and functional expression. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32711-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
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923
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Xu B. A new family programme in Zhejiang province. CHINA POPULATION TODAY 1994; 11:10-2. [PMID: 12346835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
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924
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Heyman M, Grandér D, Bröndum-Nielsen K, Cederblad B, Liu Y, Xu B, Einhorn S. Interferon system defects in malignant T-cells. Leukemia 1994; 8:425-34. [PMID: 8127147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Deletions of chromosome 9p21-22 occur in acute lymphocytic leukemia (ALL), melanoma and glioma. With some exceptions, these deletions include the alpha- and beta-interferon (IFN) genes. In this study, the frequency of alpha- and beta-IFN gene deletions was investigated in 17 T-cell lines, and losses of IFN genes were related to other aspects of the IFN system. Deletions of alpha-/beta-IFN genes were observed in 7/17 cell lines. In two cases the deletions were homozygous for both loci. In most cases aberrations of chromosome 9 were also apparent on cytogenetic analysis. An increased proportion (40% as compared to the expected 13%) of the remaining ten cell lines showed homozygosity for all five common polymorphic alpha-/beta-IFN markers, possibly implicating allelic deletion by loss of heterozygosity (LOH) in some of these clones. The cell lines showed a large variability in IFN production, IFN-alpha receptor number, susceptibility to IFN measured as induction of the enzyme 2',5' oligoadenylate synthetase and cell growth inhibition. No correlations between loss of IFN genes and IFN-producing capacity, or susceptibility to IFN, were found. Of the seven cell lines with a normal IFN-gene dosage and heterozygosity for the alpha- and beta-IFN genes, three had a deficiency in their IFN-producing capacity and one was also insensitive to growth inhibition by IFN. All IFN-producing cell lines predominantly produced beta-IFN.
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925
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Wang X, Xu B, Souza SC, Kopchick JJ. Growth hormone (GH) induces tyrosine-phosphorylated proteins in mouse L cells that express recombinant GH receptors. Proc Natl Acad Sci U S A 1994; 91:1391-5. [PMID: 7509070 PMCID: PMC43164 DOI: 10.1073/pnas.91.4.1391] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Porcine and bovine GH receptor (GHR) cDNAs were stably expressed in mouse L cells, which normally do not possess detectable levels of mouse GHR. Expression of the GHR cDNAs resulted in specific binding of 125I-labeled GH by these cell lines. To study GHR-related signaling events in these cells, protein tyrosine phosphorylation was examined. In GH-treated cells, a tyrosine-phosphorylated protein with a molecular mass of approximately 95 kDa (pp95) was increased dramatically (approximately 100-fold) relative to non-GH-treated cells. The amount of pp95 within the cells after GH treatment was positively correlated with the number of GHRs on the cells. Tyrosine phosphorylation of pp95 could not be induced by prolactin, insulin, insulin-like growth factor I, interleukin 2, epidermal growth factor, platelet-derived growth factor, or fibroblast growth factor. Phosphorylation of pp95 was found to be a rapid event that could be observed 60 sec after GH treatment. Also, pp95 appears to exist as a complex of two proteins, i.e., pp95 and pp96. The GH-induced response by these cells may be of use in screening GH analogs for biological activity.
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