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G Xing

Publications and source records attributed to G Xing.

At least 37 records · Page 2Linked to original sources
PubMed2000

Characterization, chromosomal assignment, and tissue expression of a novel human gene belonging to the ARF GAP family.

We have identified and characterized a novel human ADP-ribosylation factor GTPase-activating protein (ARFGAP1) gene that is related to other members of the ARF GAP family. The full-length cDNA for human ARFGAP1 was cloned following the identification of an EST obtained by large-scale cDNA library sequencing through a Blast search of public databases. Structurally, ARFGAP1 encodes a polypeptide of 516 amino acids, which contained a typical GATA-1-type zinc finger motif (CXXCX(16)CXXC) with the four cysteine residues that are highly conserved among other members of the ARF GAP family. The conserved ARF GAP domain may emphasize the biological importance of this gene. The ARFGAP1 gene, which contained 16 exons ranging from 0.5 to 9.3 kb, was mapped to human chromosome 22q13.2-q13.3 using radiation hybridization and in silico analyses. ARFGAP1 is strongly expressed in endocrine glands and testis. Interestingly, the expression of ARFGAP1 in testis is about sixfold higher than that in ovary, indicating a possible role of ARFGAP1 in the physiological function of sperm. Expression of ARFGAP1 in four human fetal tissues and seven cancer cell lines was also detected.

ADP-Ribosylation Factors↗
PubMed2000

[Accumulation of ABA and ODAP in Lathyrus sativus under water stress].

The roots of fifteen days old Lathyrus sativus seedlings were treated by PEG, PEG + ABA and ABA, and their leaves were sampled to determine the contents of endogenic ABA, ODAP, MDA and H2O2 and the activity of superoxide dismutase, catalase, peroxidase and glutathione reductase. The results showed that after treated, the contents of ABA and ODAP in leaves increased markedly. The addition of exogenous ABA decreased the increment of MDA and H2O2 contents and retarded the attenuation of CAT activity, which were induced by PEG stress, and enhanced the GR activity. In addition, when materials were treated with exogenous ABA in a long time, the ABA content in leaves was increased markedly, and ODAP was then accumulated. There was no significant effect on metabolism of active oxygen in the early days(0-3 days) of ABA treatment, but the activities of SOD, POD, CAT and GR decreased, and the contents of MDA and H2O2 increased in leaves of Lathyrus sativus with the duration of ABA treatment(7-15 days). The results indicated that ABA could promote the accumulation of ODAP in leaves of Lathyrus sativus.

Abscisic Acid↗
PubMed2000

[Audiological findings and mitochondrial DNA mutation in a large family with matrilineal sensorineural hearing loss].

OBJECTIVE: To explore audiological features of matrilineal non-syndromic deafness and its molecular mechanism. METHODS: A large family with 41 members having inherited deafness was studied. Complete history and the data of general and otolaryngological examinations were collected. All subjects were screened for mitochondrial DNA A1555G mutation by molecular analysis. Audiological evaluation included puretone audiometry, auditory brainstem responses and transiently evoked otoacoustic emissions. RESULTS: All subjects were in good health generally. Molecular analysis showed that all maternal relatives with or without hearing loss harbored the A1555G mitochondrial mutation. No mutation was found among spouses and paternal relatives. Audiological results showed notable symmetric bilateral sensorineural hearing loss in 17 of 20 maternal relatives, in which 5 cases had a progressive hearing loss in the recent 11 years. The age of appearance of hearing loss ranged from 1 to 50 years. CONCLUSION: All hearing-impaired subjects of this family had late-onset sensorineural hearing loss. Most of which were progressive. The A1555G mitochondrial mutation in the 12S rRNA gene is responsible for the disorder. Other factors, such as nuclear genes or environmental determinants, may influence the clinical expression of mutant mtDNA.

Acoustic Impedance Tests↗
PubMed2000

[Whole genome-wide scanning for a large pedigree with matrilineal deafness].

OBJECTIVE: To search responsible nuclear genes for matrilineal non-syndromic deafness. METHODS: Whole genome-wide scanning was performed to analyze the 365 short tandem repeats in a deaf pedigree with maternal inheritance using DNA pooling strategy. Frequencies of allele in one patient pool were compared with that in one unaffected relative pool as well as in one normal control pool. Linkage analysis was also conducted in some positive loci. RESULTS: Allele from 45 loci occurred more frequently in the patient pool than that in the unaffected relative pool and the control pool. No linkage was found from any candidate locus investigated. CONCLUSION: 45 positive loci obtained from this family may be as the candidate positions for matrilineal non-syndromic deafness.

Deafness↗
PubMed1999

Identification and characterization of receptor for mammalian hepatopoietin that is homologous to yeast ERV1.

Hepatopoietin (HPO) is a novel polypeptide mitogen specific for hepatocytes and hepatoma cell lines, which is derived from liver and supports its regeneration. To determine whether HPO acts via a receptor-based signal transduction, recombinant human hepatopoietin was labeled by iodination and used to characterize its binding activity by specific displacement test and Scatchard analysis in primarily cultured rat hepatocytes and human hepatoma Hep-G2 cells. The binding was saturable and specific because it was replaceable by HPO but not by epidermal growth factor, transforming growth factor-alpha, or insulin. Scatchard analysis indicated the presence of a single class of high affinity receptor with dissociation constant (Kd) of 2 and 0.7 pM, and a receptor density of about 10, 000 sites/cell and 55,000 sites/cell in the rat hepatocytes and human hepatoma cells, respectively. The Kd values were consistent with the half-maximum dose of HPO activity. Affinity cross-linking of the receptor with 125I-HPO revealed a polypeptide of molecular mass approximately 90 kDa by SDS-polyacrylamide gel electrophoresis. Thus, the molecular mass of the HPO receptor was calculated to be about 75 kDa. These data demonstrated the existence of an HPO receptor in hepatocytes and hepatoma cells, which may account for biological effect.

Animals↗
PubMed1999

[Observation of distortion product otoacoustic emissions in recovery course of sudden deafness].

OBJECTIVE: To realize the DPOAE resulting in sudden deafness and to investigate the changes of OAE in the recovery course of sudden deafness. METHOD: The basic characters of distortion product OAE (DPOAE) were studied in 60 ears of 30 cases with sudden deafness. The treatment and following-up were carried on too. RESULT: The incidence and amplitude of OAEs in the affected ears were lower than that of normal ears and normal group, and the threshold of DPOAE was higher too. In the recovery course the amplitude and threshold of DPOAE were improved with the restoration of auditory threshold, but the restoring rate (RR) of auditory threshold was higher. CONCLUSION: The DPOAE in sudden deafness implies a serious sensorineural hearing loss. In the recovery course, the amplitude and threshold of DPOAE is later than that of the pure-tone behavioral threshold, which implies that DPOAE is a sensitive and direct way in reflecting the function of cochlea.

Adult↗
PubMed1999

[An introduction of solvent-free(SPME) technique].

Solid-phase microextraction (SPME) is a solvent-free sample preparation technique in which a fused silica fiber coated with polymeric organic liquid is introduced into the sample. In this paper, theoretical aspects, operating models, factors of influencing sensitivity, applications and future development are introduced briefly with 19 references.

Chromatography, Gas↗
PubMed1999

[Particle repositioning maneuver for benign paroxysmal positional vertigo of posterior semicircular canal].

OBJECTIVE: To determine the effectiveness of particle repositioning maneuver (PRM) for the treatment of benign paroxysmal positional vertigo (BPPV). METHODS: Thirty one patients with BPPV of the posterior semicircular canal treated between July 1996 and June 1998 were retrospectively analyzed. Patients received a single treatment of PRM based on the hypothesis that the vertigo and nystagmus of BPPV were due to debris floating in the long arm of the posterior canal (canalithiasis). Treatment outcome was classified as cure (asymptomatic), improvement reduction of symptoms > 50%, or no change. RESULTS: After a single treatment of PRM, complete remission of vertigo and nystagmus were found in 67.7% of the patients and improvement of the symptoms was found in 19.4% of the patients. The total improvement rate was 87.1%. CONCLUSION: The particle repositioning maneuver was effective for most of the patients with benign paroxysmal positional vertigo and can be recommended as the first-line treatment modality.

Adult↗
PubMed1998

Prenatal expression of inwardly rectifying potassium channel mRNA (Kir4.1) in rat brain.

The levels and cellular localization of the mRNA encoding the inwardly rectifying potassium ion channel Kir4.1 were investigated in the embryonic rat brain by Northern blots and in situ hybridization. This transcript was absent at embryonic day 13 (E13), whereas it was clearly present in E14-15 preparations, principally in the neuroepithelium of the cerebral cortex, thalamus, and hypothalamus. At later embryonic stages (E17-20), Kir4.1 mRNA levels increased and expanded to the mantle zone, such as the cortical plate, hippocampus, thalamus, and hypothalamus. The early appearance of Kir4.1 mRNA in various brain regions suggests an involvement of the channel in cell proliferation, migration and differentiation in the rat CNS.

Animals↗
PubMed1998

Neural plasticity and emotional memory.

Posttraumatic stress disorder is the pathological replay of emotional memory formed in response to painful, life-threatening, or horrifying events. In contrast, depression is often precipitated by more social context-related stressors. New data suggest that different types of life experiences can differentially impact biochemistry, physiology, anatomy, and behavior at the level of changes in gene expression. Repeated separation of neonatal rat pups from their mother results in many long-lasting alterations in biology and behavior paralleling that in depression, including hypercortisolism. The role of the amygdala in modulating emotional memory is highlighted, as well as some of its unique properties such as metaplasticity (i.e., the differential direction of long-term adaptation, either potentiation or depression) in response to the same input as a function of the prior history of stimulation. The implications of these emerging data on the physiological and molecular mechanisms underlying emotional memory emphasize the particular importance of prevention and early intervention.

Amygdala↗
PubMed1997

5-HT1A receptor mRNA expressions differ in the embryonic spinal cord of male and female rats.

During critical periods of development, the effects of testosterone (T) on promoting androgenization of the central nervous system (CNS) are reflected not only by behavior, morphology, and hormone secretion but also by gene expression. The mechanisms involved in sexual differentiation of the CNS, however, remain incompletely defined. The current set of experiments examined with in situ hybridization the dimorphism in 5-HT1A receptor mRNA expression in the embryonic rat spinal cord and the possible role of T in the dimorphism. We found sex-related differences in expression of 5-HT1A mRNA in the spinal cord, which were altered by a single injection of T. The results suggest that this gonadal steroid is responsible for the sexual dimorphism in 5-HT1A mRNA expression occurring during the critical period.

Animals↗
PubMed1997

Transactivation of an intronic hematopoietic-specific enhancer of the human Wilms' tumor 1 gene by GATA-1 and c-Myb.

The Wilms' tumor 1 gene (WT1) encodes a zinc-finger transcription factor which is expressed in a tissue-specific manner. Our studies indicate that in addition to the promoter, other regulatory elements are required for tissue-specific expression of this gene. A 258-base pair hematopoietic specific enhancer in intron 3 of the WT1 gene increased the transcriptional activity of the WT1 promoter by 8-10-fold in K562 and HL60 cells. Sequence analysis revealed both a GATA and a c-Myb motif in the enhancer fragment. Mutation of the GATA motif decreased the enhancer activity by 60% in K562 cells. Electrophoretic mobility shift assays showed that the GATA-1 protein in K562 nuclear extracts binds to this motif. Cotransfection of the enhancer containing reporter construct with a GATA-1 expression vector showed that GATA-1 transactivated this enhancer, increasing the CAT reporter activity 10-15-fold. Similar analysis of the c-Myb motif by cotransfection with the enhancer CAT reporter construct and a c-Myb expression vector showed that c-Myb transactivated the enhancer by 5-fold. A DNase I-hypersensitive site has also been mapped in the 258-base pair enhancer region. These data suggest that GATA-1 and c-Myb are responsible for the activity of this enhancer in hematopoietic cells and may bind to the enhancer in vivo.

Base Sequence↗
PubMed1997

Rat nurr1 is prominently expressed in perirhinal cortex, and differentially induced in the hippocampal dentate gyrus by electroconvulsive vs. kindled seizures.

We isolated a rat orphan nuclear hormone receptor from a brain cortex cDNA library. The sequence of the cDNA insert was 2154 bp with an open reading frame of 1794 bp encoding a putative protein of 598 amino acids and predicted molecular mass of 65 kDa. The deduced amino acid sequence showed a strong homology to the mouse nurr1 and human NOT1 orphan nuclear hormone receptors of the NGFI-B/nur77/NAK1 gene subfamily. We refer to this rat clone as r-nurr1. Northern blot analysis showed that r-nurr1 mRNA was highly expressed in the brain and moderately in the lung as a 4.0 kb transcript. A smaller transcript of 2.5 kb was also detected in the testes. The level of r-nurr1 transcript in the heart, skeletal muscle, liver, kidney and spleen was marginal. In situ hybridization showed that r-nurr1 mRNA was constitutively expressed in various regions of the CNS, particularly in the deeper layers (IV to VI) of the perirhinal cortex and area 2 of parietal cortex. We further evaluated the modulation of r-nurr1 expression in CNS by an electroconvulsive seizure (ECS) and by an amgydala-kindled seizure. A single ECS administered via earclip electrodes induced a rapid and transient increase of r-nurr1 mRNA in the granule cells of the dentate gyrus, being significant at 15 min after the seizure, maximal approximately 1 h and back to baseline at 4 h. The amygdala kindled seizure revealed a less robust and restricted nurr-1 induction in the CNS, as only two of the four kindled animals showed a unilateral induction of nurr1 mRNA in the dentate gyrus. These results suggest that r-nurr1 is an immediate-early gene that is differentially induced by ECS vs. kindled seizures. In addition, as r-nurr1 is prominently expressed in the specific brain sites associated with memory acquisition and consolidation, it may play a role in memory processing.

Animals↗
PubMed1997

[Cloning and squencing of human thrombopoietin (hTPO) cDNA and it's expression in COS-7 cells].

Two hTPO cDNA segments (N-terminal and C-terminal) were amplified from human fetal liver mRNA by using separate reverse-transcription PCR reactions, and cloned into pUC19. Their sequences were identical with that previously reported. Then the full length cDNA of hTPO was obtained from the two cDNA fragments, cloned into the shuttle vector pSVK3 and transiently expressed in COS-7 cells. The activity of the expression product was demonstrated with the stimulation of CFU-Meg.

Animals↗
PubMed1995

Rat PPAR delta contains a CGG triplet repeat and is prominently expressed in the thalamic nuclei.

We have isolated a new rat sequence containing motifs of a nuclear hormone receptor from a brain cDNA library. The deduced amino acid sequence encoded by the cDNA clone showed a strong homology to the human NUCI and the mouse peroxisome proliferator activated receptor delta (PPAR delta). We therefore refer to this new clone as rat PPAR delta (rPPAR delta). The new feature of rPPAR delta is a 14 CGG triplet repeat on the 5' untranslated region, not previously reported in either NUCI or mPPAR delta. We found that rPPAR delta was expressed as a 3.5-kb transcript which showed a wide distribution in adult rat tissues. Abundant expression was detected in brain, heart, skeletal muscle, kidney and lung. Weaker expression was noted in the liver, spleen and testis. To determine the specific brain localization of rPPAR delta we performed in situ hybridization analysis. Prominent expression was observed in the thalamus, particularly in the posterior part of the ventral medial nucleus, a site responsive to pain and cold stress. These results raise the possibility that PPAR delta might play a role in modulating response to thermal and pain sensations.

Amino Acid Sequence↗
PubMed1993

Human hepatic stimulator substance: a product of gene expression of human fetal liver tissue.

Cloning of human hepatic stimulator substance requires clarification of whether the substance is the product of gene expression of liver cells. In this article the translation experiment in Xenopus laevis oocytes indicates that poly (A)+ messenger RNA of human fetal liver cells could conduct the biosynthesis of human hepatic stimulator substance. The translated human hepatic stimulator substance is a heat-, acid- and alkaline-resistant, but specific hepatic-stimulating, protein with a molecular weight in the range of 10 to 30 kD and with secreting ability. The characteristics of the translated human hepatic stimulator substance are consistent with those of biochemically purified human hepatic stimulator substance from human fetal liver cells. These results demonstrate that human hepatic stimulator substance is a product of gene expression of human fetal liver cells and that the complementary DNA of human hepatic stimulator substance could be screened from the complementary DNA library of human fetal liver tissue.

Animals↗