PubMed Health⌕ Search

Biomedical subjects

X Ren

Publications and source records attributed to X Ren.

At least 19 recordsLinked to original sources
PubMed2006

Analysis of the bovine neutrophil transcriptome during glucocorticoid treatment.

The objective of this study was to characterize a large portion of the bovine neutrophil transcriptome following treatment with the anti-inflammatory glucocorticoid dexamethasone (Dex). Total RNA was isolated from blood neutrophils of healthy cattle (5 castrated male Holsteins) immediately following cell purification (0 h) or after ex vivo aging for 4 h with or without added Dex. Additional neutrophils were cotreated with a glucocorticoid receptor (GR) antagonist (RU486) and Dex for 4 h. RNA was amplified, dye labeled (Cy3 or Cy5), and hybridized to a series of National Bovine Functional Genomics Consortium (NBFGC) microarrays. LOWESS data normalization followed by mixture model analyses showed that 11.15% of the spotted NBFGC cDNAs (2,036/18,263) were expressed in 4-h (untreated) neutrophils. Subsequent two-step mixed-model analysis detected (P < or = 0.05) 1,109 differentially expressed genes, of which contrast analysis indicated those that were independently responsive to aging (1,064), Dex (502), RU486 + Dex (141), or RU486 (357). In silico analysis revealed that 416 of the differentially expressed genes are unknown, 59 did not cluster well based on known function, and 634 clustered into 20 ontological categories. Independent validation of differential expression was done for 14 of the putatively Dex-responsive genes across these categories. Results showed that Dex induced rapid translocation of GR into the neutrophil nucleus and signaled dramatic alterations in expression of genes that delay apoptosis, enhance bactericidal activity, and promote tissue remodeling without inflammation or fibrosis. Thus these findings revealed hitherto unappreciated plasticity of blood neutrophils and potentially novel anti-inflammatory/wound-healing actions of glucocorticoids.

Animals↗
PubMed2006

gamma-Hydroxybutyrate induces cyclic AMP-responsive element-binding protein phosphorylation in mouse hippocampus: an involvement of GABA(B) receptors and cAMP-dependent protein kinase activation.

gamma-Hydroxybutyrate is a widely used recreational drug. Its abuse has been associated with cognitive impairments and development of tolerance and dependence. However, the neural mechanisms underlying these effects remain unclear. In the present study we investigated the possible cellular signaling mechanisms that might mediate gamma-hydroxybutyrate's action. Acute administration of gamma-hydroxybutyrate (500 mg/kg, i.p.) was found to cause a rapid and long-lasting increase in the phosphorylation level of the cAMP-responsive element-binding protein in mouse (C57/BL6) hippocampus. Pretreatment with the specific GABA(B) receptor antagonist [3-[1-(R)-[(3-cyclohexylmethyl)hydroxyphosphinyl]-2-(S)-hydroxy-propyl]amino]ethyl]-benzoic acid (20 mg/kg, i.p.) prevented the action of gamma-hydroxybutyrate, confirming a GABA(B) receptor-mediated mechanism. In addition, acute gamma-hydroxybutyrate administration induced a significant increase in cytosolic cAMP-dependent protein kinase activity in the hippocampus, and pretreatment with the cAMP-dependent protein kinase inhibitor H-89 could prevent the effect of gamma-hydroxybutyrate on cAMP-responsive element-binding protein phosphorylation, indicating a direct involvement of cAMP-dependent protein kinase in gamma-hydroxybutyrate-induced cAMP-responsive element-binding protein phosphorylation. On the other hand, the increased expression of phosphorylated cAMP-responsive element-binding protein was not observed in the hippocampus of mice subjected to repeated gamma-hydroxybutyrate exposure, suggesting the development of a gamma-hydroxybutyrate-induced desensitization of the signaling pathway leading to cAMP-responsive element-binding protein activation. Since cAMP-responsive element-binding protein activation has been implicated in a variety of neural plasticities, our findings may have revealed a new mechanism underlying gamma-hydroxybutyrate-induced neuroadaptations.

Adjuvants, Anesthesia↗
PubMed2006

Experimental study on in vitro tumor cell killing by focused bi-frequency ultrasound activated hematoporphyrin derivatives.

OBJECTIVE: As ultrasound has become an important therapeutic technique on tumor, in order to find the cell-killing effect of focused bi-frequency ultrasound activated hematoporphyrin derivatives, experimental study was processed in vitro. METHODS: Tumor cells K562 and SW-480 were killed by focused bi-frequency ultrasound activated hematoporphyrin (Hp) derivatives under optimized ultrasonic parameters and the cell-killing effect was tested by MTT (Thiazolyl blue: 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) technique. RESULTS: The lower frequency (0.6 MHz) was better than the higher (1.1 MHz) in activating hematoporphyrin derivatives; the bi-frequency was better than mono-frequency, and the cell-killing efficiency was 2-3 times of sum of the two kinds of ultrasounds which constitute bi-frequency. Incubation for the 16 h was better than 4 h after the cells exposed to the ultrasound. CONCLUSION: The method of killing tumor cells by focused bi-frequency ultrasound activated hematoporphyrin derivatives is presented and evaluated in this paper.

Apoptosis↗
PubMed2006

piggyBac-like elements in the tobacco budworm, Heliothis virescens (Fabricius).

We identified two different groups of piggyBac-like elements (PLE) in the tobacco budworm, Heliothis virescens, and named them HvPLE1 and HvPLE2. An intact copy of HvPLE1 revealed the characteristics of PLE: inverted terminal repeats, inverted subterminal repeats, and an open reading frame encoding transposase, whereas other HvPLE1 copies and all the HvPLE2 copies carried disruptive mutations in the region encoding transposase. We also identified none to two bands per genome hybridized to a probe of Trichoplusia ni piggyBac in genomic Southern blotting, which are different from HvPLE1 or HvPLE2. Analysis of the sequences of multiple copies of HvPLE1 and HvPLE2 suggests that the PLEs are closely related to the T. ni piggyBac, of relatively young age, and independently entered the H. virescens genome.

Amino Acid Sequence↗
PubMed2006

Intact mariner-like element in tobacco budworm, Heliothis virescens (Lepidoptera: Noctuidae).

An intact mariner-like element was isolated from the genome of tobacco budworm, Heliothis virescens. This is the first report of an intact mariner element after the initial identification of Mos1 from Drosophila mauritiana. The full-length Hvmar1 has 30 bp inverted terminal repeats and a complete 1065 bp open reading frame (ORF) encoding the transposase with a 'D,D(34)D' motif in the catalytic domain. Polymerase chain reaction results show that at least one insertion of the Hvmar1 element is conserved in this Heliothis strain. Phylogenetic analysis demonstrated that Hvmar1 belongs to the irritans subfamily.

Amino Acid Sequence↗
PubMed2006

Detection of human chromosomal abnormalities using a new technique combining 4',6-diamidino-2-phenyl-indole staining and image analysis.

Chromosomal abnormalities are associated with a variety of diseases. We have developed a new technique for detecting chromosomal abnormalities, and the technique combines conventional 4',6-diamidino-2-phenyl-indole staining (DAPI) with image analysis. The image analysis consists of two simple steps: deconvolution and three-dimensional reconstruction. The technique has been reported for analyzing plant chromosomes but has not been applied to analyze human chromosomes yet. To test the technique, we analyzed five translocations: 46,XX,t(3;21)(12;18), 46,XX,t(11;22), 46,XY,t(7;22), 46,XY,t(11;18), and 46,XY,t(3;7). The results showed that the karyotype of the 46,XX,t(3;21)(12;18) was 46,XX,t(3;21)(q11.1;p13),t(12;18) (q21.2;q23), and the karyotypes of the 46,XX,t(11;22), 46,XY,t(7;22), 46,XY,t(11;18), and 46,XY,t(3;7) were 46,XX,t(11;22)(q23;q12.1); 46,XY,t(7;22)(q32;q13.2); 46,XY,t(11;18)(q13.3;q23), and 46,XY,t(3;7)(q22.1;p13), respectively. The identity of derivative chromosomes involved in the translocations was verified by chromosome painting as well as FISH analyses with centromere probes. The new technique has two advantages: the procedure is simple and convenient, and the results are accurate. The technique has the potential to be used in cytogenetic studies and clinical diagnosis of human diseases in the future.

Adult↗
PubMed2006

Comparison of membrane biofouling in nitrification and denitrification for the membrane bioreactor (MBR).

Batch filtration tests were conducted to compare the characteristics of membrane biofouling with regard to nitrification and denitrification. A Modified Fouling Index (MFI) was obtained using a stirred cell tester. The denitrification assays showed higher membrane fouling rates than the nitrification assays. The fouling became worse, not only due to pore blocking resistance, but also from cake layer resistance after denitrification. The Extracellular Polymeric Substances (EPS) concentration and relative hydrophobicity were decreased after denitrification, resulting in floc deterioration. The floc deterioration was assumed to have increased the cake layer resistance in the filtration test. The protein Soluble Microbial Products (SMP) concentration, portion of high molecular weight in carbohydrate SMP and relative hydrophobicity were increased after denitrification, which was assumed to cause membrane pore blocking. The changes in the EPS and SMP characteristics were the main fouling parameters in denitrification.

Biomass↗
PubMed2006

FK506 in the treatment of children with nephrotic syndrome of different pathological types.

OBJECTIVE: To evaluate the efficacy of FK506 in the treatment of children with nephrotic syndrome of different underlying pathology. METHODS: 12 patients were treated with FK506 with a dosage of 0.1 - 0.15 mg/kg/d while corticosteroid dose was tapered stepwise. This therapeutic course lasted 3 - 6 months during which the plasma concentration ofFK506 was monitored. RESULTS: 12 children with different pathological types nephrotic syndrome were treated with FK506, including 4 cases of MCN, 6 cases of MsPGN, and 1 case of MPGN and 1 case of FSGS. After 2-month duration, 8 patients got complete remission including 4 cases of MCN and 4 cases of MsPGN and 3 children including 1 case of MsPGN, 1 case of MPGN, and 1 case of FSGS got partial remission. Only 1 child with MsPGN was considered to be a treatment failure. The overall response rate was 91.67% with the plasma concentration of FK506 maintained at 5 approximately 12 ng/ml, and the response time was 10 - 38 days. After 1-month duration, all patients except one experienced a reduction in proteinuria to normal levels or a partial response (50% reduction in protein excretion), significant increase in serum albumin, decrease in serum cholesterol and triglyceride and disappearance of edema. 2 months later, in 11 patients, blood biochemical values had returned to normal levels. The drug was generally well-tolerated. 3 patients had anorexia, nausea, vomiting. 2 patients experienced transient elevated serum creatinine which was reversible after the adjustment of dosage. 3 patients had minor changes in urine NAG. Only 2 of all patients relapsed. CONCLUSION: FK506 is one of the effective immunosuppressants. In this study, FK506 in combination with a small doses of steroid while decreasing FK506 dosage plays a role in consolidating the curative effect and preventing relapse. In conclusion, FK506 may be effective in the treatment of nephrotic syndrome.

Adolescent↗
PubMed2005

Distributions of HLA class I alleles and haplotypes in Northern Han Chinese.

Human leukocyte antigen (HLA) class I allelic genotypes were determined in 105 unrelated Han ethnic individuals inhabiting the northern China area. A total of 19 HLA-A alleles, 49 HLA-B alleles and 24 HLA-Cw alleles were detected. Through the analyses of two and three loci haplotypes of HLA-A, HLA-B, and HLA-C loci, 11 HLA-A-B-Cw haplotypes, 19 HLA-A-B haplotypes, 18 HLA-A-Cw haplotypes, and 24 HLA-B-Cw haplotypes with the frequencies of higher than 0.01 were revealed. The Nei's genetic distance (GD) was estimated, and the NJ dendrogram showed that Northern Han had a higher GD to Southern Han (0.233) than those to the Korean (0.138) or other Northern ethnic groups, suggesting that Northern Han had more mixed blood with the ethnic groups originally in Northeast Asia. Our results provide useful information on the further study of evolution and relationships of Chinese ethnic groups and disease association in terms of HLA class I genes.

Alleles↗
PubMed2004

Two whitebacked planthopper resistance genes in rice share the same loci with those for brown planthopper resistance.

The whitebacked planthopper (WBPH), Sogatella furcifera, and brown planthopper (BPH) Nilaparvata lugens Stål are important sucking insects of rice (Oryza sativa L.) crops throughout the world. Rice 'B5', which has derived its resistance genes from the wild rice O. officinalis Wall ex Watt, is a line that is highly resistant to both WBPH and BPH. Previously, two resistance genes against BPH, Qbp1, and Qbp2 in 'B5' had been mapped onto chromosome 3 and chromosome 4, respectively. In this study, we employed a mapping population composed of 187 recombinant inbred lines (RILs), produced from a cross between 'B5' and susceptible variety 'Minghui63', to locate the WBPH and BPH resistance genes. A RFLP survey of the bulked extremes from the RIL population identified two genomic regions, one on chromosome 3 and the other on chromosome 4, likely containing the resistance genes to planthoppers. QTL analysis of the RILs further confirmed that two WBPH resistance genes were mapped on the same loci as Qbp1 and Qbp2, using a linkage map with 242 molecular markers distributed on 12 rice chromosomes. Of the two WBPH resistance genes, one designated Wbph7(t) was located within a 1.1-cM region between R1925 and G1318 on chromosome 3, the other designated Wbph8(t) was within a 0.3-cM region flanked by R288 and S11182 on chromosome 4. A two-way analysis of variance showed that two loci acted independently with each other in determining WBPH resistance. The results have significant implications in studying the interactions between sucking insects and plants and in breeding programs of resistance to rice planthoppers.

Animals↗
PubMed2004

Fluorescence studies of single biomolecules.

Single-molecule fluorescence has the capability to detect properties buried in ensemble measurements and, hence, provides new insights about biological processes. Ratiometric methods are normally used to reduce the effects of excitation beam inhomogeneity. Fluorescence resonance energy transfer is widely used but there are problems in inserting the fluorophores in the correct position on the biomolecule, particularly if the structure is not known. We have recently developed two-colour coincidence single-molecule fluorescence that addresses this problem. This method can be used to determine quantitatively the multimerization states of biomolecules, in solution without separation. The future prospects of single-molecule fluorescence as applied to biological molecules are discussed.

Fluorescence Resonance Energy Transfer↗
PubMed2004

Characterization of a novel HLA-DQB1 allele, DQB1*020102.

A novel human leukocyte antigen (HLA)-DQB1 allele, DQB1*020102, was detected in a 28-year-old woman of Han ethnic in Guangzhou, China. Compared with HLA-DQB1*020101 and HLA-DQB1*0202, they differed in only one nucleotide at the position 167 (C to T) of exon 2, which was a highly conserved position. This is a synonymous mutation, which does not cause any change in the amino acid sequence of mature protein.

Base Sequence↗
PubMed2003

Calcium-sensing receptor stimulates PTHrP release by pathways dependent on PKC, p38 MAPK, JNK, and ERK1/2 in H-500 cells.

Elevated extracellular calcium ([Ca2+]o) and other agonists potentially acting via the calcium-sensing receptor (CaR) increase parathyroid hormone-related peptide (PTHrP) release from H-500 Leydig cells. Here, we provide strong evidence for the CaR's involvement by using a dominant negative CaR that attenuates high [Ca2+]o-induced PTHrP release. This effect is likely transcriptional, because high [Ca2+]o upregulates the PTHrP transcript, an effect that is abolished by actinomycin D. Regulation of PTHrP release by the CaR involves activation of PKC as well as ERK1/2, p38 MAPK, and JNK pathways. However, we show for the first time that high [Ca2+]o-induced activation of the stress-activated protein kinase SEK1 is PKC independent, because there is an additive effect of a PKC inhibitor in combination with the JNK inhibitor on [Ca2+]o-stimulated PTHrP release. Furthermore, high [Ca2+]o, in a PKC-independent fashion, induces phosphorylation of ERK1/2, SEK1, p38 MAPK, and its downstream transcription factor ATF-2. We conclude that CaR regulation of PTHrP release in H-500 cells involves activation of PKC as well as the ERK1/2, p38 MAPK, and JNK pathways.

Animals↗
PubMed2002

Developments in therapeutics for pulmonary arterial hypertension.

For many years, the management of pulmonary hypertension has been frustrated by an inadequate understanding of its pathology and limited therapeutic options, but this is changing rapidly. Recently, novel insight into the pathogenesis of primary pulmonary hypertension (PPH) has been provided by the demonstration of mutations in BMPR2 and ALK-1 genes in a significant number of patients with the condition. These genes encode members of the TGF-b receptor superfamily and their integrity is important in the maintenance of normal pulmonary vascular structure and function. At the same time, there has been a major advance in the treatment of the condition due to development of 2 orally active pharmacological agents, bosentan and sildenafil, which demonstrate some selectivity for the pulmonary vasculature. This review examines how the management of PPH and severe pulmonary hypertension in associated diseases has changed and looks at exciting future developments.

Antihypertensive Agents↗
PubMed2001

Hyperactive phosphoinositide signaling pathway in platelets of depressed patients: effect of desipramine treatment.

There is some evidence to suggest that certain neurotransmitter receptors, such as adrenergic and serotonergic receptors and receptor-linked signaling systems, may be altered in depression. Serotonin(2A) and alpha(2)-adrenergic receptors are linked to the phosphoinositide (PI) signaling system in platelets and brain. To examine if the PI signaling system is altered in depression, we studied thrombin- and sodium fluoride-stimulated inositol phosphate(1) (IP(1)) formation before and during desipramine (DMI) treatment in platelets of depressed patients and normal control subjects. We determined thrombin- and sodium fluoride-stimulated IP(1) formation in platelets obtained from hospitalized depressed patients during a drug-free baseline period and after 6 weeks of DMI treatment, and drug-free non-hospitalized normal control subjects. Depressed subjects were diagnosed according to DSM-IV criteria, and severity of illness was assessed with the Hamilton Depression Rating Scale. We observed that thrombin-stimulated IP(1) formation in platelets of depressed patients was significantly higher compared with that of normal control subjects. There were no significant differences in sodium fluoride-stimulated IP(1) formation between depressed patients and normal control subjects. We also did not find any significant effect of treatment with DMI on either thrombin- or sodium fluoride-stimulated IP(1) formation in platelets of depressed patients, which continued to be significantly higher after 6 weeks of treatment with DMI, compared with normal control values. Our studies found a hyperactive PI signaling system in platelets of depressed patients. This hyperactive system may be related either to an increased number of thrombin receptors or to a generalized overstimulation of this pathway; however, since we did not observe any differences in sodium fluoride-stimulated IP(1) formation, it appears that, although the sites distal to the receptors may be altered, this abnormality is probably not related to the abnormalities in G proteins.

Adult↗
PubMed2001

Generation of three selenium-containing catalytic antibodies with high catalytic efficiency using a novel hapten design method.

A novel strategy for design of haptens that were used to produce catalytic antibodies was developed and three monoclonal antibodies, 3G5, 2F3, and 5C9, were generated using this strategy. These monoclonal antibodies were converted into selenium-containing abzymes by chemically modifying the hydroxyl group of serines followed by sodium hydrogen selenide displacement. These selenium-containing abzymes exhibited remarkable glutathione peroxidase activity, which surpasses the activity of some native glutathione peroxidases. The activities of the selenium-containing abzymes Se-3G5, Se-2F3, and Se-5C9 which catalyzed reduction of hydroperoxides by glutathione were 2.23, 4.20, and 3.79 times that of rabbit liver glutathione peroxidase, respectively. Detailed steady-state kinetics study on Se-2F3 was carried out and the value of k(cat)/K(m) (H(2)O(2)) was found to be 2.11 x 10(7) M(-1) min(-1) which was supposed to be one of the highest among the known catalytic antibodies. The data of association constants and glutathione peroxidase activities of these catalytic antibodies and the steady-state kinetics of Se-2F3 showed that the method might be a remarkably efficient one for generating catalytic antibodies with glutathione peroxidase activity.

Amino Acid Sequence↗
PubMed2001

A novel dicyclodextrinyl ditelluride compound with antioxidant activity.

Reactive oxygen species (ROS) primarily arise from products of normal metabolic activities and are thought to be the etiology of many diseases. A novel dicyclodextrinyl ditelluride (2-TeCD) compound was designed to be a functional mimic of the glutathione peroxidase that normally removes ROS. 2-TeCD exhibited highly catalytic efficiency and good water solubility. Antioxidant activity was studied by using ferrous sulfate/ascorbate-induced mitochondria damage model system. 2-TeCD protected the mitochondria against oxidative damage in a dose-dependent manner and exhibited also great antioxidant ability in comparison with 2-phenyl-1,2-benziososelenazol-3(2H)-one. The mimic may result in better clinical therapies for the treatment of ROS-mediated diseases.

Animals↗