Biomedical subjects

J Xiao

Publications and source records attributed to J Xiao.

At least 37 records · Page 2Linked to original sources

PubMed2001

Bioactivities of culture supernatants from retroviral packaging cells carrying the mouse Fas ligand gene.

The bioactivities of culture supernatants from retroviral packaging cells carrying the mouse Fas ligand (mFasL) gene was investigated. FasLcDNA was cloned into PLXIN with an internal ribosome entry site to link two cistrons through gene recombination technology, PLXIN and the recombinant vector PLFIN were separately transfected into PA317 retrovirus packing cell line by lipofectamine 2000, and the resistant clones were selected with G418 selective medium. The integration of genome DNA was assayed by genomic DNA PCR. NIH3T3 cells were transduced by the culture supernatants from PA317 carrying the mFasLcDNA gene, and were selected with G418 selective medium, so as to select the PLFIN-PA317 clone capable of producing higher titer of supernatants. The levels of mFasL protein on NIH3T3 cells membrane were assayed by flow cytometry (FCM). The biological activity of mFasL on NIH3T3 cells membrane was investigated by the inducing apoptosis of Fas+ Yac-1 cells co-cultured with NIH3T3 cells expressing Fas ligand. To explore the direct mFasL cytotoxicity of culture supernatants from retroviral packaging cells carrying the mFasL gene, the culture supernatants from PLFIN-PA317 and PLXIN-PA317 were separately co-cultured with Yac-1 cells in parallel. The recombinant PLFIN was successfully constructed. The highest titer of supernatants from twelve resistant clones was 8.5 x 10(5) colony-forming-unit (CFU)/ml. The NIH3T3 cells transfected by above supernatants had a higher level of mFasL (53.81 +/- 6.9%), and significantly induced the apoptosis of Fas+ Yac-1 cells (56.78 +/- 4.5%), as both were cocultured for 5 h at 1:1 ratio, whereas it is 7.08 +/- 3.4% in control group (P < 0.01). Supernatant from PLFIN-PA317 could also directly induce the apoptosis of Yac-1 within 5 h of incubation. Thus, the culture supernatants from PLFIN-PA317 possessed both infectivity and cytotoxicity of mFasL.

3T3 Cells↗

PubMed2001

On the mechanism of the protective effects of nitroglycerin and nicorandil in cardiac anaphylaxis.

Previous investigations have shown that nitric oxide donors and nicorandil can suppress allergic reaction. In the present study, the protective effects of nitroglycerin and nicorandil on cardiac anaphylaxis were examined. Presensitized guinea-pig hearts challenged with specific antigen caused a marked decrease in coronary flow (CF), left ventricular pressure (LVP) and its derivatives (+/-dp/dtmax), increase in heart rate, and prolongation of P-R interval. Nitroglycerin (300 nM) or nicorandil (100 microM) markedly increased the content of calcitonin gene-related peptide (CGRP) concomitant with a significant improvement of the cardiac dysfunction and alleviation of the extension of P-R interval. Nicorandil at a concentration of 100 microM also inhibited the sinus tachycardia and histamine release. The protection afforded by nitroglycerin was abolished by glibenclamide, a blocker of ATP-sensitive potassium channels, or by CGRP8-37, the selective CGRP receptor antagonist, or by pretreatment with capsaicin, which depletes endogenous CGRP. The inhibitory effect of nicorandil on cardiac anaphylaxis was abolished only by glibenclamide but not by pretreatment with capsaicin. These results suggest that nitroglycerin and nicorandil possess a protection of cardiac anaphylactic injury. The present study also suggests that the protective effect of nitroglycerin may be related to stimulation of CGRP release and opening the KATP channel, and that the effect of nicorandil is mainly due to the activation of the KATP channel.

Anaphylaxis↗

PubMed2001

A polymorphism in the promoter region of catalase is associated with blood pressure levels.

Catalase is an important antioxidant enzyme that detoxifies H2O2 into oxygen and water and thus limits the deleterious effects of reactive oxygen species (ROS). Because chronic exposure to excess ROS may contribute to vascular damage, we investigated whether genetic variation in catalase was associated with susceptibility to essential hypertension (EHYT) in 324 individuals (at least 50 years old) who were randomly sampled from an isolated population living in Xiangchang, China. They were screened for genetic variation in the promoter of catalase by direct sequencing. In total, four single nucleotide polymorphisms (SNPs) were identified. The association between the SNPs and EHYT was investigated by a linear regression model under phenotypic selection; in our analyses, we used both SBP>150 mmHg and SBP>160 mmHg as thresholds. A SNP 844 bp upstream of the start codon (SNP-844) demonstrated strong evidence of association with EHYT (SBP>150 mmHg: F=5.09, P=0.008; SBP>160 mmHg: F=7.13, P=0.002). This is the first study to implicate genetic variation in catalase in susceptibility to EHYT and suggests that polymorphisms in promoter regions may be particularly relevant to the study of complex diseases.

Aged↗

PubMed2001

Permeant ion-dependent changes in gating of Kir2.1 inward rectifier potassium channels.

We studied the effect of monovalent thallium ion (Tl(+)) on the gating of single Kir2.1 channels, which open and close spontaneously at a constant membrane potential. In cell-attached recordings of single-channel inward current, changing the external permeant ion from K(+) to Tl(+) decreases the mean open-time by approximately 20-fold. Furthermore, the channel resides predominantly at a subconductance level, which results from a slow decay (tau = 2.7 ms at -100 mV) from the fully open level immediately following channel opening. Mutation of a pore-lining cysteine (C169) to valine abolishes the slow decay and subconductance level, and single-channel recordings from channels formed by tandem tetramers containing one to three C169V mutant subunits indicate that Tl(+) must interact with at least three C169 residues to induce these effects. However, the C169V mutation does not alter the single-channel closing kinetics of Tl(+) current. These results suggest that Tl(+) ions change the conformation of the ion conduction pathway during permeation and alter gating by two distinct mechanisms. First, they interact with the thiolate groups of C169 lining the cavity to induce conformational changes of the ion passageway, and thereby produce a slow decay of single-channel current and a dominant subconductance state. Second, they interact more strongly than K(+) with the main chain carbonyl oxygens lining the selectivity filter to destabilize the open state of the channel and, thus, alter the open/close kinetics of gating. In addition to altering gating, Tl(+) greatly diminishes Ba(2+) block. The unblocking rate of Ba(2+) is increased by >22-fold when the external permeant ion is switched from K(+) to Tl(+) regardless of the direction of Ba(2+) exit. This effect cannot be explained solely by ion-ion interactions, but is consistent with the notion that Tl(+) induces conformational changes in the selectivity filter.

Animals↗

PubMed2001

Origin-independent assembly of Kaposi's sarcoma-associated herpesvirus DNA replication compartments in transient cotransfection assays and association with the ORF-K8 protein and cellular PML.

Six predicted Kaposi's sarcoma virus herpesvirus (KSHV) proteins have homology with other well-characterized herpesvirus core DNA replication proteins and are expected to be essential for viral DNA synthesis. Intact Flag-tagged protein products from all six were produced from genomic expression vectors, although the ORF40/41 transcript encoding a primase-helicase component proved to be spliced with a 127-bp intron. The intracellular localization of these six KSHV replication proteins and the mechanism of their nuclear translocation were investigated. SSB (single-stranded DNA binding protein, ORF6) and PPF (polymerase processivity factor, ORF59) were found to be intrinsic nuclear proteins, whereas POL (polymerase, ORF9), which localized in the cytoplasm on its own, was translocated to the nucleus when cotransfected with PPF. PAF (primase-associated factor, ORF40/41), a component of the primase-helicase tripartite subcomplex together with PRI (primase, ORF56) and HEL (helicase, ORF44), required the presence of all five other replication proteins for efficient nuclear translocation. Surprisingly, even in the absence of a lytic cycle replication origin (ori-Lyt) and any known initiator or origin binding protein, the protein products of all six KSHV core replication genes cooperated in a transient cotransfection assay to form large globular shaped pseudo-replication compartments (pseudo-RC), which excluded cellular DNA. These pseudo-RC structures were confirmed to include POL, SSB, PRI, and PAF but did not contain any newly synthesized DNA. Similar to the human cytomegalovirus system, the peripheries of these KSHV pre-RC were also found to be surrounded by punctate PML oncogenic domains (PODs). Furthermore, by transient cotransfection, the six KSHV core replication machinery proteins successfully replicated a plasmid containing EBV ori-Lyt in the presence of the Epstein-Barr virus-encoded DNA binding initiator protein, ZTA. The KSHV-encoded K8 (ORF-K8) protein, which is a distant evolutionary homologue to ZTA, was incorporated into pseudo-RC structures formed by transient cotransfection with the six core KSHV replication genes. However, unlike ZTA, K8 displayed a punctate nuclear pattern both in transfected cells and at early stages of lytic infection and colocalized with the cellular PML proteins in PODs. Finally, K8 was also found to accumulate in functional viral RC, detected by incorporation of pulse-labeled bromodeoxyuridine into newly synthesized DNA in both tetradecanoyl phorbol acetate-induced JSC-1 primary effusion lymphoblasts and in KSHV lytically infected endothelial cells.

Amino Acid Sequence↗

PubMed2001

The effect of chronic exposure to fatty acids on gene expression in clonal insulin-producing cells: studies using high density oligonucleotide microarray.

Fatty acids affect insulin secretion of pancreatic beta-cells. Investigating gene expression profiles may help to characterize the underlying mechanism. INS-1 cells were cultured with palmitate (0, 50, and 200 microM) for up to 44 d. Insulin secretion and expressions of 8740 genes were studied. We found that basal insulin secretion increased in cells exposed to palmitate. The response to glucose stimulation declined on d 44 in cells cultured at 200 microM palmitate. In response to 50 and 200 microM palmitate exposure, expression was changed in 11 and 99 genes on d 2 and 134 and in 159 genes on d 44, respectively. Genes involved in fatty acid oxidation were up-regulated, whereas those involved in glycolysis were down-regulated with 200 microM palmitate. A suppression of insulin receptor and insulin receptor substate-2 gene expression was found on d 44 in cells cultured at 200 microM palmitate. In conclusion, chronic exposure to low palmitate alters insulin secretion as well as gene expression. The number of genes that changed expression was palmitate dose and exposure time dependent. Randle's fatty acid-glucose cycle seems to be operative on the gene transcription level. A modification of expression of various genes may contribute to the functional changes.

Cell Line↗

PubMed2001

Skin reflectance in the Han Chinese and Tibetan populations.

Genetic and environmental factors are involved in the determination of skin pigmentation in humans. With the recent development of statistical and genetic tools in mapping complex traits in humans, it is becoming feasible to utilize such methods in identifying genes involved in skin pigmentation. Furthermore, the use of new portable reflectance spectroscopy instruments such as the Photovolt ColorWalk colorimeter allows researchers to measure skin reflectance of a large number of subjects with ease and accuracy. We used a new portable instrument (Photovolt ColorWalk) to study the skin reflectance of 372 Han Chinese and 274 Tibetan individuals to establish background reflectance measurements of unexposed skin of the inner upper arm in these two populations. In addition, we explored the effect of various factors such as age and gender on skin reflectance.

Adolescent↗

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 sedimentation rate and fractional dimension during flocculation with modified natural polymer and polymeric aluminum chloride].

The sedimentation rate and fractional dimension of the floc was studied during the process of the organic waste water treatment with modified natural polymer (CMS) and polymeric aluminum chloride (PAC). Irregular garrulous form of the floc was observed with microscope and electron-scanning microscope. The results showed that the sedimentation rate was 2.6 mm/min with the modified natural polymer (CMS) and 1.7 mm/min without CMS in condition of keeping the pH value to 6.86 and added quantity of PAC to 80 mg/L. The fractional dimension of the floc Df was calculated to be 1.70 in the best sedimentation rate.

Aluminum Chloride↗

PubMed2001

[The mechanical chemical attachment of artificial cartilage (PVA-hydrogel) to metal substrate (or underlying bone)].

The biocompatibility and tribological characteristics of PVA-hydrogel are excellent, but it is very difficult to make the artificial cartilage material (PVA-hydrogel) attach to the underlying bone. In this study, PVA-hydrogel is attached to the metal fibre mesh by means of micro-mechanical interlock methods at first, then the surface of metal fibre mesh is bonded to the underlying bone by the bone cement(PMMA). In this way, the artificial cartilage can be firmly attached to the underlying bone(or metal substrate). Microstructure analysis and mechanical tests show that the attachment between artificial cartilage and the metal substrate is firm.

Animals↗

PubMed2001

[Apoptosis in pressure overload-induced heart hypertrophy].

Pressure overload can result in heart hypertrophy, and induce apoptosis, but the phenomenon of apoptosis during the forepart of cardiomyocyte hypertrophy remains unclear. The aim of this study was to inquire into the process of cardiomyocyte apoptosis during the forepart of cardiomyocyte hypertrophy. We constructed the hypertrophy model by transverse aortic constriction of male SD rat. The apoptosis ratio was detected by TUNEL method and FCM. The result demonstrated that hypertrophy indexes increased with the time of constriction, reached the highest level at day 7, maintained that level, and then decreased at day 91. The apoptosis ratio of cardiomyocyte at day 4 was higher than that at day 0 detected by FCM method, and the ratio at day 7 was markedly lower than that at day 4. After day 28, the apoptosis ratio of cardiomyocyte went up again with the time of constriction after surgery. TUNEL method revealed that positive nuclei were observed in cardiomyocytes exclusively in the left ventricle; the apoptosis ratio increased when constriction continued. TUNEL method confirmed the result of FCM. These data indicate that cardiac hypertrophy is initiated by apoptosis of cardiomyocyte, these two factors(hypertrophy and apoptosis) maintain the balance between growth and death during the early short period of aortic constriction, and when aortic constriction goes on they are involved in the pathogenesis of heart remodeling.

Adaptation, Physiological↗

PubMed2001

[X-linked recessive Charcot-Marie-Tooth disease and Cx32 gene mutation].

OBJECTIVE: To study the Cx32 gene mutation in a X-linked recessive Charcot-Marie-Tooth disease (CMTXR) family. METHODS: Mutation analysis of Cx32 was screened by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) combined with DNA direct sequencing in 4 patients, 9 unaffected family members and 50 unrelated normal individuals. RESULTS: Arg15Gln mutation was found in 4 patients and 3 unaffected family members. CONCLUSION: The mutation of Cx32 can also cause CMTXR. Using PCR-SSCP combined with DNA direct sequencing can make gene diagnosis to CMTXR that is caused by Cx32 mutation.

Adult↗

PubMed2001

Role of calcitonin gene-related peptide in prostaglandins-mediated ischemic preconditioning in guinea pig hearts.

AIM: To examine the role of calcitonin gene-related peptide (CGRP) in ischemic preconditioning induced by prostaglandins in isolated guinea pig hearts. METHODS: The isolated guinea pig hearts were perfused in a Langendorff model. The heart rate, coronary flow, left ventricular pressure, and its first derivatives (+/-dp/dt(max)) were recorded and the calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and 6-keto-PGF(1 alpha) were measured. RESULTS: Endothelin-1 (200 pmol in 1 mL K-H buffer) reduced the left ventricular developed pressure and its first derivatives (+/-dp/dt(max)), heart rate, and coronary flow. Preconditioning with two cycles of 5-min global ischemia and 5-min reperfusion attenuated endothelin-1 induced myocardial injury, and concentrations of both CGRP and 6-keto-PGF(1alpha) in the coronary effluent were markedly raised in the preconditioning periods. Pretreatment with capsaicin, which depletes endogenous CGRP, abolished the elevated level of CGRP concomitantly with loss of the cardioprotection induced by ischemic preconditioning. CGRP(8-37) (100 nmol/L), a selective CGRP1 receptor antagonist, also abolished the protective effects of ischemic preconditioning. After pretreatment with indometacin (10 micromol/L), an inhibitor of cyclooxygenase, the protective effects of ischemic preconditioning were abolished and the release of 6-keto-PGF1alpha was no longer elevated. Pretreatment with indometacin abolished the elevated level of CGRP in the coronary effluent. CONCLUSION: Endogenous prostaglandins are involved in the protective effects of ischemic preconditioning, and the beneficial effects of prostaglandins are mediated by CGRP in the guinea pig heart.

6-Ketoprostaglandin F1 alpha↗

PubMed2001

[The development of a respiration and temperature monitor].

This paper introduces the design of a monitoring system to measure the respiration and temperature of a body with an 8Xc196 single-chip microcomputer. This system can measure and display the respiration wave, respiration frequency and the body temperature in real-time with a liquid crystal display (LCD) and give an alarm when the parameters are beyond the normal scope. In addition, this device can provide a 24 hours trend graph of the respiration frequency and the body temperature parameters measured. Data can also be exchanged through serial communication interfaces (RS232) between the PC and the monitor.

Body Temperature↗

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

[Sewage treatment by the canal reactor with biomembrane].

This paper studies that utilizing sewage canal (waterway) of city to treat sewage on bases of researching water pollution, hydrological data and topography of the canal. A new canal reactor of bacteria membrane with continuous operation was designed, made and studied in the laboratory. The operation results of the reactor show that the reactor could effectively treat the sewage of city. The average data of continuous operation during 3 months showed that the removal ratios of CODCr and BOD5 were 88% and 95% in the range of CODCr concentration 180 mg.L(-1)-450 mg.L-1 in the inlet, separately. The technology also has the advantage of low capital cost, low operation cost. This will create the condition to apply the way to practical living sewage treatment of canal.

Bacteria↗

PubMed2000

RINT-1, a novel Rad50-interacting protein, participates in radiation-induced G(2)/M checkpoint control.

Rad50, an structural maintenance of chromosomes (SMC) protein family member, participates in a variety of cellular processes, including DNA double-strand break repair, cell cycle checkpoint activation, telomere maintenance, and meiosis. Disruption of Rad50 in mice leads to lethality during early embryogenesis, indicating its essential function in normal proliferating cells. In addition to its ability to form a complex with the DNA double-strand break repair proteins Mre11 and NBS1, Rad50 may interact with other cellular proteins to execute its full range of biological activities. A novel 87-kDa protein named RINT-1 was identified using the C-terminal region of human Rad50 as the bait in a yeast two-hybrid screen. Human RINT-1 shares sequence homology with a novel protein identified in Drosophila melanogaster, including a coiled-coil domain within its N-terminal 150 amino acids, a conserved central domain of about 350 amino acids, and a C-terminal region of 90 amino acids exhibiting 35--38% identity. The conserved central and C-terminal regions of RINT-1 are required for its interaction with Rad50. While Rad50 and RINT-1 are both expressed throughout the cell cycle, RINT-1 specifically binds to Rad50 only during late S and G(2)/M phases, suggesting that RINT-1 may be involved in cell cycle regulation. Consistent with this possibility, MCF-7 cells expressing an N-terminally truncated RINT-1 protein displayed a defective radiation-induced G(2)/M checkpoint. These results suggest that RINT-1 may play a role in the regulation of cell cycle control after DNA damage.

Amino Acid Sequence↗

PubMed2000

Inhibition of cardiac tumor necrosis factor-alpha production by calcitonin gene-related peptide-mediated ischemic preconditioning in isolated rat hearts.

Previous investigations have demonstrated that calcitonin gene-related peptide (CGRP) plays an important role in the mediation of ischemic preconditioning in rats. In the present study, we examined signal transduction pathways of CGRP-mediated ischemic preconditioning. Thirty minutes of global ischemia and 40 min of reperfusion caused a dramatic decrease in myocardial function, and a significant increase in the release of cardiac creatine kinase in the coronary effluent and in the content of tumor necrosis factor-alpha (TNF-alpha) in myocardial tissues. However, ischemic preconditioning (three cycles of 5-min ischemia and 5-min reperfusion) or pretreatment with CGRP for 5 min dramatically improved the recovery of cardiac function, and reduced the release of cardiac creatine kinase and the TNF-alpha content. The effect of ischemic preconditioning was abolished by CGRP-(8-37), the selective CGRP receptor antagonist, and by capsaicin, which depletes sensory nerve neurotransmitter content, but was unaltered by treatment with glibenclamide, a blocker of the ATP-sensitive potassium (K(ATP)) channel. The protective effects of exogenous CGRP-induced preconditioning were also not blocked by glibenclamide. These results suggest that the cardioprotective effects afforded by CGRP-mediated ischemic preconditioning are related to inhibition of cardiac TNF-alpha production, but not to activation of the K(ATP) channel.

Animals↗