Biomedical subjects

J Xue

Publications and source records attributed to J Xue.

At least 19 recordsLinked to original sources

PubMed2003

Chronic intermittent hypoxia decreases the expression of Na/H exchangers and HCO3-dependent transporters in mouse CNS.

Chronic intermittent hypoxia (CIH) is a component of several disease states, including obstructive sleep apnea, which results in neurocognitive and cardiovascular morbidity. Because chronic hypoxia can induce changes in metabolism and pH homeostasis, we hypothesized that CIH induces changes in the expression of acid-base transporters. Two- to three-day-old mice, exposed to alternating cycles of 2 min of hypoxia (6.0-7.5% O2) and 3 min of normoxia (21% O2) for 8 h/day for 28 days, demonstrated decreases in specific acid-base transport protein expression in most of the central nervous system (CNS). Sodium/hydrogen exchanger isoform 1 (NHE1) and sodium-bicarbonate cotransporter expression were decreased in all regions of the CNS but especially so in the cerebellum. NHE3, which is only expressed in the cerebellum, was also significantly decreased. Anion exchanger 3 protein was decreased in most brain regions, with the decrease being substantial in the hippocampus. These results indicate that CIH induces downregulation of the major acid-extruding transport proteins, NHE1 and sodium-bicarbonate cotransporter, in particular regions of the CNS. This downregulation in acid-extruding capacity may render neurons more prone to acidity and possibly to injury during CIH, especially in the cerebellum and hippocampus. Alternatively, it is possible that O2 consumption in these regions is decreased after CIH, with consequential downregulation in the expression of certain cellular proteins that may be less needed under such circumstances.

Acid-Base Equilibrium↗

PubMed2003

Expression of Na+/H+ and HCO3- -dependent transporters in Na+/H+ exchanger isoform 1 null mutant mouse brain.

Acid-base transporters, such as the sodium-hydrogen exchangers (NHEs) and bicarbonate-dependent transporters, play an important role in the regulation of intracellular pH (pH(i)) in the CNS. Previous studies from our laboratory have shown that the absence of the major NHE isoform 1 (NHE1) reduced the steady-state pH(i) and recovery rate from an acid load in the hippocampal neurons not only in HEPES but also in HCO(3)(-) solutions (Yao et al., 1999). The purpose of the current study was to determine whether the NHE1 null mutation affects the expression of pH-regulatory transporters in the mouse CNS. Immunoblotting and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) were performed to examine the protein and mRNA levels of NHE1-4, electrogenic sodium-bicarbonate cotransporter 1 variants (NBCe1), and brain-specific anion exchanger 3 (AE3) in four brain regions (cerebral cortex, hippocampus, cerebellum and brainstem-diencephalon). NHE1 null mutant mice were compared with their wild type controls at the average age of approximately 4 weeks. Our results revealed that the NHE1 null mutation caused a significant increase in NHE3 in the cerebellum (84% for protein, 105% for mRNA), an increase in NBCe1 expression in the brainstem-diencephalon (approximately 40-50% for protein, 9-15% for mRNA), as well as a decrease in AE3 in the hippocampus (approximately 60% for protein, 24% for mRNA). We conclude that the NHE1 null mutation does alter the expression of other membrane transporters at both protein and mRNA levels. The alteration is region-specific. An increase in acid extruders (e.g. NHE3) and a decrease in acid loaders (e.g. AE3) suggest that there are some compensatory mechanisms that occur in NHE1 null mutant mice.

Animals↗

PubMed2001

Differential gene expression of adenosine A1, A2a, A2b, and A3 receptors in the human enteric nervous system.

Adenosine receptors (ADORs) in the enteric nervous system may be of importance in the control of motor and secretomotor functions. Gene expression and distribution of neural adenosine A1, A2a, A2b, or A3 receptors (Rs) in the human intestine was investigated using immunochemical, Western blotting, RT-PCR, and short-circuit current (I(sc)) studies. Adenosine A1R, A2aR, A2bR, or A3R mRNAs were differentially expressed in neural and nonneural layers of the jejunum, ileum, colon, and cecum and in HT-29, T-84, T98G, and Bon cell lines. A1R, A2aR, A2bR, and A3R immunoreactivities (IRs) were differentially expressed in PGP 9.5-immunoreactive neurons. A2bR IR occurs exclusively in 50% of submucosal vasoactive intestinal peptide (VIP) neurons (interneurons, secretomotor or motor neurons) in jejunum, but not colon; A2aR is also found in other neurons. A3R IR occurs in 57% of substance P-positive jejunal submucosal neurons (putative intrinsic primary afferent neurons) and less than 10% of VIP neurons. Western blots revealed bands for A3R at 44 kDa, 52 kDa, and 66 kDa. A2aR and A2bR are coexpressed in enteric neurons and epithelial cells. 5'-N-methylcarboxamidoadenosine or carbachol evoked an increase in I(sc). A2bR IR is more prominent than A2aR IR in myenteric neurons, nerve fibers, or glia. A1R is expressed in jejunal myenteric neurons and colonic submucosal neurons. Regional differences also exist in smooth muscle expression of ADOR IR(s). It is concluded that neural and nonneural A1, A2a, A2b, and A3Rs may participate in the regulation of neural reflexes in the human gut. Clear cell and regional differences exist in ADOR gene expression, distribution, localization, and coexpression.

Blotting, Western↗

PubMed2001

Visual-mediated regulation of retinal CaMKII and its GluR1 substrate is age-dependent.

Previous studies have shown that multifunctional calcium/calmodulin-dependent protein kinase II (CaMKII) and one of its substrates, the glutamate receptor, are key players in experience-driven synaptic plasticity in several areas of the central nervous system (CNS). To determine if CaMKII and the glutamate receptor are regulated by visual activity in the retina, we compared dark-reared (DR; 1 week) rats with control rats raised in a diurnal light-dark cycle (LD), at the following ages: postnatal day 12 (P12d), 2-month (2m) and 6-month (6m) old. The mRNA levels of CaMKIIalpha and beta were determined by a competitive reverse transcription polymerase chain reaction (competitive RT-PCR) method. The protein levels of these two subunits were evaluated by immunoblots. The data show that the mRNAs for CaMKIIalpha and beta were increased about 8-fold and 10-fold, respectively, in the retinae of DR P12d rats. As for the proteins, 2- and 2.6-fold elevations for CaMKIIalpha and beta, respectively, were evident. The GluR1 subunit of the AMPAR (AMPAR-GluR1) was also evaluated in antibody-treated blots and found to be increased about 2-fold after 1 week of dark rearing in the retinae of P12d rats. This type of experience-driven molecular change was age-dependent, showing less increase in 2m old rats and not present in 6m old rats. Returning DR 2m old rats to the LD environment for 1 week was sufficient to restore the dark-induced changes to the levels of the age-matched LD controls. Based on the data, a theoretical model for activity-dependent modulation of the developing retinal synapses is proposed.

Age Factors↗

PubMed2001

The modification of NMDA receptors by visual experience in the rat retina is age dependent.

Extensive studies have shown that the activation of N-methyl-D-aspartate receptors (NMDARs) and the subsequent rise in the levels of postsynaptic calcium are critical events in the initiation of synaptic plasticity. Modification of the amount, or of the subunit composition of NMDARs, alters receptor function thereby affecting the development and/or efficacy of synaptic transmission. In the present study, a Western blot analysis was employed to investigate the effects of visual experience and age on the differential expression of NMDARs in the rat retina. A crude synaptic membrane fraction (SPM) was prepared and assayed with antibodies specific for either the NR1, NR2A or NR2B subunits. Relative to control animals raised in a diurnal light-dark cycle, a period of 1 week of dark-rearing caused an increase in the relative amount of NR1, a decrease in the level of NR2A, and no change in the level of NR2B subunit expression in postnatal day 12 rats. At 2 months of age, 1 week of dark-rearing had less effect, and at 6 months of age there was no difference between dark-reared and control animals. The effect of light exposure on dark-reared animals was tested for the 2-month-old animals. Light exposure for long periods (days), but not short periods (h), could reverse the dark-rearing effects. These data provide evidence for a developmentally regulated plasticity of NMDAR subunits in the retina.

Age Factors↗

PubMed2001

Testicular protein Spag5 has similarity to mitotic spindle protein Deepest and binds outer dense fiber protein Odf1.

Outer dense fibers (ODF) and the fibrous sheath (FS) are major cytoskeletal structures in the mammalian sperm tail. The molecular mechanisms underlying their morphogenesis along the axoneme or their function are poorly understood. Recently, we reported the cloning and characterization of Odf2, a major ODF protein, and Spag4, an axoneme-binding protein, by virtue of their strong interaction with Odf1, the 27 kDa major ODF protein. We proposed a crucial role for leucine zippers in molecular interactions during sperm tail morphogenesis. Here we report the cloning and characterization of a novel gene, Spag5, which encodes a 200 kDa testicular protein that interacts strongly with Odf1. Spag5 is transcribed and translated in pachytene spermatocytes and spermatids. It bears 73% similarity with the mitotic spindle protein Deepest of unknown function. We identified two putative leucine zippers in the C-terminal part of the Spag5 protein, the downstream one of which is involved in interaction with Odf1. Interestingly, these motifs are present in Deepest. These results highlight the importance of the leucine zipper in sperm tail protein interactions. Mol. Reprod. Dev. 59: 410-416, 2001.

Amino Acid Sequence↗

PubMed2001

Study of an Au colloid self-assembled electrode and its application to the determination of carbon monoxide.

A novel electrochemical sensor has been developed for the detection of carbon monoxide. The chemically modified electrode, prepared by reaction of cysteine and then an Au colloid of size approximately 15 nm with a platinum microelectrode, has excellent catalytic activity toward carbon monoxide, with an oxidation potential of +600 mV relative to the Ag/AgCl electrode. The CO gas sensor is based on an Au colloid self-assembled modified electrode as working electrode, an Ag/AgCl electrode as reference electrode, a Pt electrode as counter electrode, and a porous film which is in direct contact with the gas-containing atmosphere. The effects on the determination of CO of different internal electrolyte solutions of perchloric acid, hydrochloric acid, sulfuric acid, nitric acid, and phosphate buffer of different concentrations were also studied. The sensor is characterized by a short response time and highly reproducible detection of CO. This sensor can be used in the field of environmental monitoring and control.

Calibration↗

PubMed2001

Studies on flavans. 1. Facile synthesis of (+/-)-7-hydroxy-3',4'-methylenedioxyflavan and (+/-)-4'-hydroxy-7-methoxyflavan by a BF3.Et2O-mediated pyran cyclization.

A facile approach for the synthesis of flavans was developed by employing a BF3.Et2O-catalyzed pyran cyclization in an aprotic polar solvent as a key step, by which concise total syntheses of (+/-)-7-hydroxy-3',4'-methylenedioxyflavan (1) and (+/-)-4'-hydroxy-7-methoxyflavan (2), two naturally occurring flavans, were achieved.

Cyclization↗

PubMed2001

Molecular cloning and sequence analyses of calcium/calmodulin-dependent protein kinase II from fetal and adult human brain. Sequence analyses of human brain calciuum/calmodulin-dependent protein kinase II.

The aims of this study were to characterize specific mRNAs and the expression pattern for isoforms of calcium/calmodulin-dependent protein kinase II (CaMKII) in the human brain. We cloned and sequenced the CaMKII alpha and beta subunit cDNAs, and used them to study the CaMKII expression in human brain. Four distinct isoforms of CAMKII were isolated. Two of them were characterized as CaMKII alpha and beta subunits. The other two showed similar nucleotide sequences, but one had a 33-bp insertion relative to the alpha subunit, and the other had a 75-bp deletion relative to the beta subunit. These alterations are located within the variable regions. These two isoforms were characterized as CaMKII alphaB and beta(e). Northern blot analysis showed that a 4.4-kb messenger RNA for the alpha isoform and a 3.9-kb messenger RNA for the beta isoform were expressed in both human fetal and adult brain to different degrees. The results indicate that CaMKII expression is developmentally regulated. The CaMKII isoform expression was confirmed in human fetal and adult brain using RT-PCR with specific primers, which flanked the CaMKII variable regions. The CaMKII alpha, alphaB, beta, beta' and beta(e) isoforms were characterized in both human fetal and adult brain.

Alternative Splicing↗

PubMed2001

A new method to incorporate age and gender into the criteria for the detection of acute inferior myocardial infarction.

Recent studies have shown that younger women are more likely to die during and after hospitalization for acute myocardial infarction (MI) than older women and men of all ages. This may be partly due to incorrect diagnosis or late detection of acute MI in younger women. At high specificity levels (>98%), the sensitivity of the initial ECG to detect acute MI may be as low as 30% when using traditional criteria by both physicians and computerized interpretation programs. This study examines if women of different age groups have a similar ECG presentation to men during acute inferior MI and if the diagnostic accuracies of the initial ECG are comparable. We analyzed chest pain ECGs from Mayo Clinic and Medical College of Wisconsin, which included 1,339 patients with acute inferior MI and 1,169 age-matched controls with noncardiac chest pain. We subdivided all groups by age (below and above 60 years) and compared ECG parameters (ST elevation, ST depression, QRS duration, R-wave amplitude, Q-wave duration and amplitude, QT interval) between genders. For inferior MI patients under age 60, women had lower ST elevations at the J point in lead II than men (57 +/- 91 microV vs. 86 +/- 117 microV, P < .02). This trend was reversed for patients over age 60 (lead a VF: 102 +/- 126 microV vs. 84+/-117 microV, P < .04; Lead III: 130+/-146 microV vs. 103+/-131 microV, P < .007). A neural network method was used to identify the most significant group of ECG parameters for detecting acute MI. An adaptive fuzzy logic method was developed for adapting to the threshold differences among the different gender and age groups. The new algorithm improved the sensitivity of acute inferior MI detection by more than 25% relative to old algorithm, while maintaining the high specificity around 98% for noncardiac chest pain patients.

Age Factors↗

PubMed2001

Gelatinase A (MMP-2) in developing tooth tissues and amelogenin hydrolysis.

Matrix metalloproteinases (MMPs) are thought to play important roles during enamel and dentin biomineralization. Previously, membrane type-1 matrix metalloproteinase (MT1-MMP) was localized to the plasma membranes of ameloblasts and odontoblasts of the developing tooth. The best-characterized function of MT1-MMP is to initiate the activation of gelatinase A (MMP-2). Thus, we hypothesized that gelatinase A may also be expressed by developing tooth tissues. A full-length porcine gelatinase A mRNA was isolated by RT-PCR homology cloning of an enamel-organ-specific cDNA library. Northern blot and in situ hybridization analyses demonstrated gelatinase A expression in developing tooth tissues. Immunohistochemical analysis localized gelatinase A close to the plasma membrane of these tissues. Furthermore, recombinant gelatinase A was demonstrated to cleave recombinant amelogenin into several fragments of differing molecular masses. Thus, gelatinase A is expressed by developing tooth tissues along with its activator MT1-MMP and may, therefore, play an important role during tooth development.

Ameloblasts↗

PubMed2001

Effects of mutating different steroidogenic factor-1 protein regions on gene regulation.

The involvement of cyclic adenosine monophosphate cAMP-dependent protein kinase A (PKA) in the regulation of the steroidogenic acute regulatory protein (StAR) and the high-density lipoprotein receptor (HDL-R) genes by steroidogenic factor-1 (SF-1) and cAMP were examined. Cotransfection studies carried out in Kin 8 cells, a Y1 cell line (mouse adrenal) with a mutation in the type I PKA regulatory subunit, demonstrated that an intact PKA is required for maximal activation and that SF-1 participates in cAMP regulation of these genes. Site-directed mutational analysis was performed to examine which SF-1 regions could be involved in SF-1 transcriptional activation of the StAR and HDL-R genes. SF-1 regions protein analyzed were amino acids Thr 60, Ser 203, Ser 431, Thr 462, and the activation function-2 domain (amino acids 449-462). Plasmids encoding each of the mutated SF-1 proteins were cotransfected with the StAR and HDL-R promoter constructs into human bladder carcinoma (HTB-9) cells in the presence or absence of dibutyryl cAMP. The results of these studies suggest that although SF-1 is required for optimal promoter response to cAMP, transcriptional activation of genes by SF-1 and cAMP are promoter dependent, perhaps resulting from gene-specific interactions of this transcription factor with other regulatory proteins.

Amino Acid Sequence↗

PubMed2001

[Single nucleotide polymorphism in beta2-adrenoceptor gene and the distribution in Chinese Han ethnic group].

OBJECTIVE: The study was conducted to investigate single nucleotide polymorphism(SNP) in beta2-adrenoceptor(beta2-AR) gene and the distribution of these identified SNPs in Chinese Han ethnic group. METHODS: beta2-AR gene was sequenced to detect SNPs by fluorescent labeling automatic sequencing method in 80 unrelated samples from territory of Dabie Mountain in Anhui province. RESULTS: A total of 8 SNPs were identified in length of 3.8 kb, including 5 SNPs in code region, 3 SNPs in regulatory region. Although the variations, -468C to G, -367T to C, -47C to T,-20T to C, +79C to G, +100G to A, +491C to T, +1098T to C have been identified in other ethnic groups, they have not been found in our study. The allele distribution of SNPs is in good unity with the Hardy-Weinberg equilibrium. CONCLUSION: The distribution of SNPs in beta2-AR gene is not equable and the SNPs in different ethnic groups differ greatly. The allele distribution of SNPs conforms well to the Hardy-Weinberg equilibrium.

Alleles↗

PubMed2001

[The transfer and expression of human clotting factor IX in muscle mediated by electroporation].

OBJECTIVE: To probe into the feasibility of increasing hFIX cDNA transfer and expression in muscle. METHODS: The high-frequency electric field was used to promote both Lac-Z-encoding plasmid pCMV beta and hFIX-expressing plasmid G1NaMCIX to transfer and express in muscle. The effects of frequency and length of square pulse, as well as eletroporation time on hFIX expression were investigated. RESULTS: Electric stimulation could increase the transfer and expression of pCMV beta in muscle, the number of X-gal positive myofiber cells in electroporation-treated mice is 2.1 times larger than that of mice not treated by electroporation (P<0.01). The most optimal electric simulation condition for hFIX cDNA transfer and expression was obtained, under this condition, the highest level of hFIX antigen in plasma is (40+/- 5.4) ng/ml and 7 times higher than that of mice without electroporation P < 0.001). CONCLUSION: Electroporation is able to enhance hFIX cDNA transfer and expression in muscle efficiently.

Animals↗

PubMed2001

A bicistronic retroviral vector to introduce drug resistance genes into human umbilical cord blood CD34+ cells to improve combination chemotherapy tolerance.

OBJECTIVE: To study whether human umbilical cord blood CD34+ cells transduced with human aldehyde dehydrogenase class-1 (ALDH-1) and multidrug resistance gene (MDR1) have increases resistance to 4-Hydroperoxycyclo-phosphamide (4-HC) and P-glycoprotein effluxed drugs. METHODS: A bicistronic retroviral vector G1Na-ALDH1-IRES-MDR1 was constructed and used to transfect the packaging cell lines GP + E86 and PA317 by LipofectAMINE method, using the medium containing VCR and 4-HC agents for cloning selection and ping-ponging supernatant infection between the ecotropic producer clone and the amphotropic producer clone, we obtained high titer amphotropic PA317 producing cells with high titers up to 5.6 x 10(5) CFU/ml. Cord blood CD34+ cells were transfected repeatedly with supernatant of retrovirus containing human ALDH-1 and MDR1cDNA under the stimulation of hemopoietic growth factors. RESULTS: Bicistronic retroviral vector construction was verified by restriction endonuclease analysis. Polymerase chain reaction (PCR), reverse transcription (RT)-PCR, Southern blot, Northern blot, fluorescenceactivated cell sorting (FACS) method and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analyses showed that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The transgenes recipient cells confered 4-fold stronger resistance to 4-HC and 5.5 to 7.2-fold P-glycoprotein effluxed drug than untransduced cells. CONCLUSION: The bicistronic retroviral vector-mediated transfer of two different types of drug resistance genes into human cord blood CD34+ cells and co-expression provided an experimental foundation for improving combination chemotherapy tolerance in tumor clinical trial.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

[Association of single nucleotide polymorphisms in code region of beta2-adrenoceptor gene with hypertension in Chinese population].

OBJECTIVE: To detect single nucleotide polymorphisms(SNPs) existing in code region of beta(2)-adrenoceptor(2-AR) gene and to investigate association of the identified SNPs with essential hypertension in Chinese Han population. METHODS: Beta(2)-AR gene was sequenced with fluorescent labelling automatic sequencing method in unrelated Chinese Han population from Dabie Mountain in Anhui Province. Genotype of the SNPs were typed with PCR-RFLP method. RESULTS: Two SNPs were identified in length of 774bp, at position + 1053 with G-->C substitution and + 1239 with A-->G substitution respectively. The frequency of genotype of the two SNPs complied well with the Hardy-Weinberg equilibrium in normal group. Distribution of genotype AA, GA, GG of the SNPs at locus + 1239 in hypertension group was significantly different from that in normal group (chi(2) = 6.70, df = 2, P < 0.05). No significant difference was observed in distribution of genotypes of the SNPs at locus + 1053 between the two groups. CONCLUSION: These results indicate that the SNPs at locus + 1239 of beta(2)-AR gene is associated with EH. The SNPs at position + 1053 was not linked to hypertension.

Aged↗

PubMed2001

[Improvement of combination chemotherapy tolerance of human umbilical cord blood CD(34)(+) cells transducted with double drug resistance genes by a bicistronic retroviral vector].

OBJECTIVE: To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human aldehyde dehydrogenase class 3 (ALDH3) and multidrug resistance gene (MDR1) could increase resistance to 4-hydroxycyclophosphamide (4-HC) and P-glycoprotein effluxed drugs. METHODS: A bicistronic retroviral vector G1Na-ALDH3-IRES-MDR1 cDNA was constructed and transfected the packaging cell lines GP + E86 and PA317 by LipofectAMINE method, using the medium containing VCR and 4-HC for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, cord blood CD(34)(+) cells were enriched with a high-gradient magnetic cell sorting system (MACS), and then repeatedly transfected with supernatant of retrovirus containing human ALDH3 and MDR1 cDNA under stimulation of hematopoietic growth factors. PCR, RT-PCR, Southern blot, Northern blot, FACS and MTT assay were used to evaluate the transfection and expression of the double genes. RESULTS: The purity of cord blood CD(34)(+) cells was approximately 91% and the recovery rate was 72%. The highest titer of recombinant amphotropic retrovirus in the supernatant was up to 6.5 x 10(5) CFU/ml. The efficiency of gene transduction was 18%, 20% and 16.7% tested by colony formation, PCR and FACS, respectively. Rhodamine 123 efflux showed 16% transduced cells with P-gp function. No helper virus was found by both nested PCR and rescue assay. The MTT analysis showed a 3.5 to 6.8-fold increase of resistance of transducted cells to cyclophosphamide and P-glycoprotein effluxes drug as compared with the nontransduced cells. CONCLUSION: The efficiency and co-expression of this dual genes transfer system provided a foundation for ameliorating combination chemotherapy toxicity in clinical trial.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2000

Charge-density-wave-induced modifications to the quasiparticle self-energy in 2H- TaSe2

The self-energy of the photohole in 2H-TaSe2 is measured by angle-resolved photoemission spectroscopy as a function of binding energy and temperature. In the charge-density wave (CDW) state, a structure in the self-energy is detected at approximately 65 meV that cannot be explained by electron-phonon scattering. A reduction in the scattering rates below this energy indicates the collapse of a major scattering channel with the formation of the CDW state accompanying the appearance of a bosonic "mode" in the excitation spectrum of the system.

Journal Article↗