Biomedical subjects

Yan Xu

Publications and source records attributed to Yan Xu.

At least 199 records · Page 11Linked to original sources

PubMed2003

+Gz protection of a new bladder anti-G system.

OBJECTIVE: A new bladder anti-G system was developed to get better +Gz protection. The purpose of this study was to assess the +Gz protection afforded by it on the centrifuge. METHOD: Six male subjects using the new bladder anti-G system were exposed to 10-15 s ladder-shaped +Gz profiles without anti-G straining maneuver (AGSM), then exposed to + 5-9 Gz simulated aerial combat maneuver (SACM) with leg straining. RESULT: The +Gz protection and the +Gz-time tolerance were obtained. The anti-G effectiveness of the advanced bladder system was 5.33 +/- 0.26 G. All subjects passed the +5-9 Gz SACM, but the effort and fatigue were lower. CONCLUSION: The +Gz protection afforded by this system is high. The suggested scheme of the new bladder anti-G system is feasible.

Adolescent↗

PubMed2003

[Management of sheath after repair of double tendons in zone II d].

OBJECTIVE: To evaluate the management of sheath after repair of double tendons in clean-cut injury or severe injury in zone II d. METHODS: Forty-eight white leghorn chickens were divided into 4 groups. Both FDS and FDP tendons in zone II d of long toes were repaired with modified Kessler suture after tendon transection in group A (clean-cut tendon injury, sheath closure), group B (clean-cut tendon injury, sheath excision), group C (severe tendon injury, sheath closure) and group D (severe tendon injury, sheath excision), respectively. Biomechanical studies of gliding excursion and work of flexion were carried out 6 weeks and 12 weeks after tendon repair. The extent of adhesion was examined. RESULTS: After 6 and 12 weeks of repair, there were no significant differences in tendon excursion and work of flexion of the toes between groups A and B. Excursions of FDP tendons in group D was significantly larger than that in group C (P < 0.05). Work of flexion and extent of adhesion in group D was significantly less than that in group C (P < 0.05). CONCLUSION: The above results indicate that sheath can be closed after repair of both FDS and FDP tendons in clean-cut injury and that sheath should be excised in severe injury in zone II d.

Animals↗

PubMed2003

[Effect of vitamin E on memory and brain monoaminergic neurotransmitter in chronic episodic hypoxia rat].

OBJECTIVE: To investigate the effect of Vitamin E (VitE) on memory and brain monoaminergic neurotransmitter level in chronic episodic hypoxia (EHYP) rat. METHODS: VitE [50 IU/ (250 g.d) or 5 IU/ (250 g.d)] was given to the EHYP rat model. The memory was evaluated by the passive avoidance test and the levels of monoaminergic neurotransmitter, including norepinephrine (NE), dopamine (DA) and 5-hydroxytryptamine (5-HT), were determined in three different brain regions (including cerebral cortex, hippocampus and striatum) using high performance liquid chromatography and electrochemical detection (HPLC-ECD). RESULTS: The performance on passive avoidance test of EHYP rats was worse than that of controlled rats (P < 0.01). The performance of rats in two different treatment groups was better than that of EHYP rats (P < 0.05), the performance of rats in high-dose group was worse than that of rats in low-dose group (P < 0.05). Compared with controlled rats, levels of monoaminergic neurotransmitters in different brain regions of EHYP rats decreased significantly (P < 0.05). Compared with EHYP rats, level of NE and DA in cerebral cortex and level of monoamine (NE, DA, and 5-HT) in hippocampus and striatum of low-dose treated rats were increased significantly (P < 0.05). Different with low-dose treated rats, only level of monoamine (NE, DA, and 5-HT) in striatum and level of 5-HT in hippocampus in high-dose treated rats were increased significantly (P < 0.05), as compared with the EHYP rats. CONCLUSIONS: vitE can improve memory and increase brain monoaminergic neurotransmitter of EHYP rats. Moreover, the effect of low-dose vitE is better than that of high-dose VitE.

Animals↗

PubMed2003

[Simultaneous determination of 3 kinds of components in Gardenia by high-performance liquid chromatography under different UV-vis wave length].

AIM: To determine 3 kinds of biologically active components (9 compounds) in Gardenia, namely geniposidic acid, gentiobioside, gardenoside, genipin geniposide, chlorogenic acid, crocin 1, crocin 2, crocin 3 and crocetin simultaneously and quantitatively. METHODS: An HPLC method detected by 3 different UV-vis waves--240 nm for geniposidic acid, geniposide, gardenoside, genipin gentiobioside, 330 nm for chlorogenic acid, 440 nm for crocin 1, crocin 2, crocin 3 and crocetin respectively, has been developed: Phenomenex Luna C18 column(250 mm x 4.6 mm ID, 5 microns) with linear gradient elution using methanol-acetotrile (9:1) and 0.3% aqueous formic acid. RESULTS: This method successfully determined 9 compounds in Gardenia (from 5 different areas) simultaneously and quantitatively. CONCLUSION: This is a more reasonable and credible quality control method for the Chinese traditional medicine.

Carotenoids↗

PubMed2003

[Genomic variations in the locus for aminopeptidase N:a putative cellular receptor for SARS-CoV spike glycoprotein].

Aminopeptidase N has been identified as the cellular receptor for human coronavirus HCoV-229E and was a putative receptor for the spike glycoprotein encoded by the SARS-associated coronavirus (SARS-CoV). We report here identification of 9 single nucleotide polymorphisms (SNPs) in ANPEP, encoding human aminopeptidase N, in Chinese. All ANPEP exons and their flanking intronic sequences were amplified from unrelated normal individuals by polymerase chain reaction (PCR) and screened using denaturing high-performance liquid chromatography (DHPLC). Nine SNPs were revealed after direct sequencing of PCR amplified fragments which showed changes of DHPLC chromatogram. Four of these polymorphisms, T321M(962C > T), S651L(1952C > T), S752N(2255G > A) and G764R(2290G > A), were non-synonymous; the remaining exonic synonymous and intronic ones were T795T(2385C > T), IVS7 + 17G > A, IVS14-16A > G, IVS17 + 12C > G and IVS17 + 44C > T. Our data may be useful for studies to investigate the role of host genetic factors in SARS pathogenesis, especially for identifying SARS-susceptible and/or anti-SARS alleles.

Animals↗

PubMed2003

[Studies of the association between angiotensinogen gene regulation and cytokines in essential hypertension].

This study is to explore the association between M235T allele polymorphism of angiotensinogen (AGT) gene and cytokines using essential hypertension probands research method. In hypertensives and controls, polymerase chain reaction combined with restriction endonuclease digestion was used to detect the target genotype variation, and enzyme-lined immunosorbant assay (ELISA) was used to detect the cytokine concentrations (IL-1, IL-6, TNF). The results showed that in hypertensives AGT gene, TT genotype was 55.88%, MT 35.29% and MM 8.82%. The ratio of T/M allele frequency was 0.735/0.265. In controls AGT gene, TT genotype was 47.46%, MT 42.37% and MM 10.17%. The ratio of T/M allele frequency was 0.686/0.314. AGT gene 235 T allele frequency in hypertensives was slightly higher than those in controls. Furthermore AGT gene 235 TT genotype and T allele frequency in middle and high grade of hypertensives were significantly higher than those in mild grade. In subjects of AGT 235 T allele group, the concentrations of IL-1, IL-6 and TNF in hypertensives were significantly higher than those in controls. In subjects of AGT gene 235 M allele frequency, the concentrations of IL-1 and IL-6 in hypertensives were no significant than those in controls. No matter in groups more than 60 years old or less than 60 years old, the concentrations of IL-1, IL-6 and TNF in hypertensives were higher than those in controls. No matter in hypertensives or controls, there were no differences in concentrations of IL-1, IL-6 and TNF when comparing groups more than 60 years old with groups less than 60 years old. The study indicated that AGT gene TT genotype and AGT gene 235 T allele frequency may be an important risk factor for hypertension. The high frequency of AGT gene 235 T allele and the high concentrations of IL-1, IL-6 and TNF in hypertensives may cause hypertension developing. It is also suggested the cytokines may effect the transcription and expression of AGT gene 235 TT genotype in hypertension. The concentrations of IL-1, IL-6 and TNF had nothing to do with age no matter hypertensives or controls.

Adult↗

PubMed2003

[Effects of tobacco on proliferation and attachment of human periodontal ligament fibroblast].

OBJECTIVE: To evaluate the effects of nicotine and tobacco extract (ST) on PDLFs morphology, structure, proliferation and attachment. METHODS: PDLFs were cultured in the presence of nicotine and ST at various concentration. The cell changes in the morphology and structure were examined by histological and transmission electrical microscope (TEM). The growth and attachment of cell were measured by MTT method. RESULTS: The size of the cells became smaller gradually and their shapes changed from shuttle type to oval or round when the concentration of nicotine and ST increased, the polarity of the cells was in disorder, ultrastructure showed that the organelles, especially rough-surfaced endoplasmic reticulum and golgi complex decreased in number, microtubule and microfilaments were disassembled, the nuclei became fewer or shrunk, the growth and attachment were dose-dependently inhibited. CONCLUSIONS: Nicotine and ST can change PDLFs' morphology and structure, they may inhibit the growth and attachment through disruption of the cytoskeleton, suggesting nicotine and ST may have pathological role on human periodontitis.

Cell Adhesion↗

PubMed2003

[Expression of constructed eukaryotic vectors carrying encoding gene of soluble human interleukin-1 receptor in mammalian cells].

OBJECTIVE: This study is to make sure if the constructed pcDNA3 carrying encoding gene of sIL-1R can be expressed in mammalian cells in vitro. METHODS: COS-1 cells and CHO cells were respectively transfected with recombinant plasmid pcDNA3/sIL-1R by liposome. The protein expression products were detected by ELISA. RESULTS: The results indicated that the protein expression products could be detected in the cell plasma and the cell culture supermatant. The expression level in experimental groups was much higher than that in control groups(P < 0.05). CONCLUSION: The constructed pcDNA3/sIL-1R can express interest protein in mammalian cells and this establishes the basis for future investigation on gene therapy of periodonititis and other inflammatory diseases.

Animals↗

PubMed2003

[The detection and significance of human papilloma virus 11b virus like particles and its serum antibody in juvenile larynx papilloma].

OBJECTIVE: To study the relationship between human papilloma virus 11b virus like particles (HPV11bVLPS) serum antibody and the development and prognosis of juvenile larynx papilloma (JLP). METHODS: Enzyme linked immunosorbent assay (ELISA) was used to detect the serum HPV11bVLP antibody (Ab) of 46 JLP's samples in different stage and 20 controls using HPV11bVLPS which was produced by recombinant bacilovirus in insect cells. Grouping: A: control group (n = 20); B: the time of onset was 1 years (n = 15); C: the time of onset was 2 years (n = 15); the patients were followed-up 1 year without recurrence (n = 8); E: The patients were followed-up 2 years without recurrence (n = 8). RESULTS: A value of HPV11bVLP Ab among A, B, C, D, E. group were: (0.073 +/- 0.035); (0.120 +/- 0.049); (0.137 +/- 0.057); (0.518 +/- 0.122); (0.557 +/- 0.144). There was a significant difference between JLP patients and the control group (P < 0.05). The level of HPV11bVLP Ab in (D + E) group (0.534 +/- 0.132) was higher than (B + C) group (0.128 +/- 0.053) (t = 14.90, P < 0.001). CONCLUSION: The results suggested that HPV serum antibody was produced in JLP with HPV infection. There is close relationship between the development and prognosis of the disease and the level of HPV11Ab in serum. The assay of serum HPV11bVLPAb and HPV-VLP could be used as immunological study of HPV11-infection associated disease.

Antibodies, Viral↗

PubMed2002

Transcriptional adaptation to cystic fibrosis transmembrane conductance regulator deficiency.

Cystic fibrosis, the most commonly inherited lethal pulmonary disorder in Caucasians, is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). To identify genomic responses to the presence or absence of CFTR in pulmonary tissues in vivo, microarray analyses of lung mRNAs were performed on whole lung tissue from mice lacking (CFTR(-)) or expressing mouse CFTR (CFTR(+)). Whereas the histology of lungs from CFTR(-) and CFTR(+) mice was indistinguishable, statistically significant increases in the relative abundance of 29 and decreases in 25 RNAs were identified by RNA microarray analysis. Of RNAs whose expression was consistently altered by the absence of CFTR, functional classes of genes influencing gene transcription, inflammation, intracellular trafficking, signal transduction, and ion transport were identified. RNAs encoding the transcription factor CCAAT enhancer-binding protein (CEBP) delta and interleukin (IL) 1beta, both known to regulate CFTR expression, were induced, perhaps indicating adaptation to the lack of CFTR. RNAs mediating lung inflammation including calgranulin-S100 family members, IL-1beta and IL-4, were increased. Likewise, expression of several membrane transport proteins that interact directly with CFTR were increased, suggesting that CFTR-protein complexes initiate genomic responses. Absence of CFTR influenced the expression of genes modulating diverse pulmonary cell functions that may ameliorate or contribute to the pathogenesis of CF.

Animals↗

PubMed2002

Aberrant methylation of the HPP1 gene in ulcerative colitis-associated colorectal carcinoma.

The HPP1 gene was cloned as a frequently methylated gene in hyperplastic polyps of the colon. It has been shown that HPP1 expression is silenced by HPP1 gene hypermethylation in sporadic colorectal cancers. To determine the role of HPP1 in ulcerative colitis (UC)-associated carcinogenesis, the prevalence of HPP1 methylation was investigated in three different histological stages of UC-associated carcinogenesis (non-neoplastic UC colon, dysplasia, and carcinoma). Quantitative methylation-specific PCR and quantitative reverse transcription-PCR were used to determine HPP1 gene methylation and expression levels, respectively. HPP1 methylation was observed in 24 of 48 (50%) adenocarcinomas and in 4 of 10 (40%) dysplasias. In contrast, no non-neoplastic UC mucosa showed HPP1 methylation. HPP1 expression in the HCT116 colon cancer cell line was restored after treatment with the demethylating agent 5-aza-2'-deoxycytidine. In conclusion, our data suggest that methylation of HPP1 is a relatively common early event in UC-associated carcinogenesis. HPP1 offers potential as a biomarker for the early detection of cancer or dysplasia in UC.

Colitis, Ulcerative↗

PubMed2002

Large-scale molecular dynamics simulations of general anesthetic effects on the ion channel in the fully hydrated membrane: the implication of molecular mechanisms of general anesthesia.

Interactions of volatile anesthetics with the central nervous system are characterized by low yet specific binding affinities. Although neurotransmitter-gated ion channels are considered the primary anesthetic targets, the mechanism of action at the molecular level remains elusive. We consider here the theoretical implications of channel dynamics on anesthetic action in a simplified membrane-channel system. Large-scale 2.2-ns all-atom molecular dynamics simulations were performed to study the effects of halothane, a clinical anesthetic, on a gramicidin A (gA) channel in a fully hydrated dimyristoyl phosphatidylcholine membrane. In agreement with experimental results, anesthetics preferentially target the anchoring residues at the channel-lipid-water interface. Although the anesthetic effect on channel structure is minimal, the presence of halothane profoundly affects channel dynamics. For 2.2-ns simulation, the rms fluctuation of gA backbone in the lipid core increases from approximately equal 1 A in the absence of anesthetics to approximately equal 1.5 A in the presence of halothane. Autocorrelation analysis reveals that halothane (i) has no effect on the subpicosecond librational motion, (ii) prolongs the backbone autocorrelation time in the 10- to 100-ps time scale, and (iii) significantly decreases the asymptotic values of generalized order parameter and correlation time of nanosecond motions for the inner but not the outer residues. The simulation results discount the viewpoint of a structure-function paradigm that overrates the importance of structural fitting between general anesthetics and yet-unidentified hydrophobic protein pockets. Instead, the results underscore the global, as opposed to local, effects of anesthetics on protein dynamics as the underlying mechanisms for the action of general anesthetics and possibly of other low-affinity drugs.

Anesthesia, General↗

PubMed2002

Affinity partitioning of glucose-6-phosphate dehydrogenase and hexokinase in aqueous two-phase systems with free triazine dye ligands.

The partitioning of glucose-6-phosphate dehydrogenase (G6PDH) (E.C. 1.1.1.49) and hexokinase (E.C. 2.7.1.1) in polyethylene glycol (PEG)-hydroxypropyl starch (PES) and PEG-phosphate aqueous two-phase systems was investigated with free triazine dyes, Cibacron Blue F3GA and Procion Red HE3B, as their affinity ligands. It was found that the free reactive triazine dyes, not bound to phase-forming polymers, preferentially partitioned in the top-PEG phase in the PEG-salt and PEG-PES systems. The effect of various parameters such as type and concentration of affinity ligands, pH of the system, molecular mass of PEG and phase composition on partitioning of the enzymes was estimated. Phosphate is a key factor affecting the enzyme partitioning in the PEG-PES system. Cibacron F3GA changed the partition coefficient of G6PDH from 0.73 to 1.59.

Chromatography, Affinity↗

PubMed2002

Intensification and stimulation therapy for human immunodeficiency virus type 1 reservoirs in infected persons receiving virally suppressive highly active antiretroviral therapy.

Highly active antiretroviral therapy (HAART) has led to significant changes in mortality and morbidity in the human immunodeficiency virus type 1 (HIV-1) epidemic. Nevertheless, because of molecular mechanisms of viral persistence, HAART does not eradicate HIV-1. Didanosine and hydroxyurea were added to the antiretroviral regimens of 3 HIV-1-infected men who were receiving stable HAART and who had HIV-1 RNA levels <50 copies/mL at the initiation of the study protocol, as a novel intensification to attack cryptic viral replication; low-dose OKT3 was then administered, followed by a course of interleukin-2, to stimulate latent provirus. Replication-competent virus was undetectable after treatment, and plasma viral RNA was either undetectable or <5 copies/mL. In trial periods during which no antiretroviral therapy was administered, the patients developed plasma viral rebound. This translational approach combines novel intensification and stimulation therapy to deplete residual HIV-1 reservoirs. Additional experimental approaches must be developed if HIV-1 eradication is to become possible in patients receiving virally suppressive HAART.

Adult↗

PubMed2002

[Insulin-like growth factor-I and cognitive function in patients with obstructive sleep apnea syndrome].

OBJECTIVE: To explore the possible biochemical mechanism of cognitive impairment in patients with obstructive sleep apnea syndrome (OSAS). METHODS: Polysomnography was administered to thirty-six patients with OSAS and eighteen education and BMI-matched controls, all males aged 40 approximately 49 for 8.5 hours at night. Early next morning blood was drawn and serum insulin-like growth factor-I (IGF-I) was determined by immunoradiometric assay. Then neuropsychological tests of visual regeneration, digital symbol, comprehensive memory and digital span were conducted. RESULTS: The quality of sleep in the patients with OSAS was significantly worse than that of the controls. The score of visual regeneration in the patients with OSAS was 8.4 +/- 2.7, significantly lower than that in control group (11.6 +/- 1.4, P < 0.01). The score of digital symbol in patients with OSAS was 36.92 +/- 8.31, significantly lower than that in the controls (47.8 +/- 6.8, P < 0.01). The serum IGF-I level of the patients with OSAS was: 127.2 +/- 87.0 ng/ml, significantly lower than that of the controls (194.03 ng/ml +/- 77.31 ng/ml, P < 0.05). The IGF-I level was significantly positively correlated with the scores of visual regeneration test (r = 0.381, P < 0.05) and digital symbol test (r = 0.330, P < 0.05), lowest SaO(2) (r = 0.371, P < 0.05), mean SaO(2) (r = 0.333, P < 0.05) and REM sleep duration (r = 0.598, P < 0.01). CONCLUSION: Decrease of serum IGF-I level may play a role in the cognitive impairment in patients with OSAS. Nocturnal hypoxemia and REM sleep deprivation may be the reason of the decrease of the serum IGF-I level in patients with OSAS.

Adult↗

PubMed2002

Rapid determination of serum melatonin by ESI-MS-MS with direct sample injection.

This paper describes a rapid, simple and sensitive analytical method for the quantitative determination of melatonin in human serum by ESI-MS-MS with direct serum sample injection and on-line extraction. The method uses N-acetyltryptamine as the internal standard. It has high specificity and sensitivity for serum melatonin analysis. The internal calibration curve shows a wide linear range from 0.500 to 200 ng/ml with a correlation coefficient, R(2) > 0.999. The limit of quantitation is 0.500 ng/ml and the limit of detection is 0.100 ng/ml with 10-microl sample injection. The recoveries of serum melatonin at three levels are approximately 70%. The intra-assay precision (n = 5) is between 0.8 and 2.0% and the inter-assay precision (n = 3) is between 1.5 and 5.9% over the calibration range. This method has a total analysis time of less than 9 min. It can be used for the measurement of melatonin in human blood.

Flow Injection Analysis↗

PubMed2002

Hypermethylation of HPP1 is associated with hMLH1 hypermethylation in gastric adenocarcinomas.

The HPP1 gene was initially discovered because of its frequent hypermethylation in hyperplastic colon polyps, but it is also hypermethylated in colorectal adenomas and carcinomas. Expression of the DNA mismatch repair gene hMLH1 is diminished or absent in some hyperplastic polyps, and it has been suggested that HPP1 inactivation is associated with the progression of microsatellite-unstable colorectal tumors. We sought then to determine the prevalence of HPP1 silencing by DNA methylation in gastric adenocarcinomas and to define any association of this event with microsatellite instability (MSI) or hMLH1 hypermethylation. Thirty-two matched normal-gastric adenocarcinoma DNA pairs were studied for MSI status and hypermethylation of HPP1 and hMLH1. Five (100%) of 5 MSI-H tumors, 2 (50%) of 4 MSI-L tumors, and 8 (35%) of 23 MSS tumors demonstrated HPP1 hypermethylation. Eight (25%) of 32 tumors (5 of 5 MSI-H, 2 of 4 MSI-L, and 1 of 23 MSS) showed evidence of hMLH1 hypermethylation. All (8 of 8) of these hMLHI-methylated tumors demonstrated concomitant methylation at the HPP1 locus: there were no cases of hMLH1 methylation occurring in the absence of HPP1 methylation. In gastric adenocarcinoma, hypermethylation frequently targets HPP1. Moreover, hMLH1 hypermethylation occurs predominantly in the setting of HPP1 hypermethylation. HPP1 hypermethylation may represent an early event in mismatch repair-deficient gastric tumorigenesis.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Chimeric human papilloma virus-simian/human immunodeficiency virus virus-like-particle vaccines: immunogenicity and protective efficacy in macaques.

Vaccines to efficiently block or limit sexual transmission of both HIV and human papilloma virus (HPV) are urgently needed. Chimeric virus-like-particle (VLP) vaccines consisting of both multimerized HPV L1 proteins and fragments of SIV gag p27, HIV-1 tat, and HIV-1 rev proteins (HPV-SHIV VLPs) were constructed and administered to macaques both systemically and mucosally. An additional group of macaques first received a priming vaccination with DNA vaccines expressing the same SIV and HIV-1 antigens prior to chimeric HPV-SHIV VLP boosting vaccinations. Although HPV L1 antibodies were induced in all immunized macaques, weak antibody or T cell responses to the chimeric SHIV antigens were detected only in animals receiving the DNA prime/HPV-SHIV VLP boost vaccine regimen. Significant but partial protection from a virulent mucosal SHIV challenge was also detected only in the prime/boosted macaques and not in animals receiving the HPV-SHIV VLP vaccines alone, with three of five prime/boosted animals retaining some CD4+ T cells following challenge. Thus, although some immunogenicity and partial protection was observed in non-human primates receiving both DNA and chimeric HPV-SHIV VLP vaccines, significant improvements in vaccine design are required before we can confidently proceed with this approach to clinical trials.

Animals↗