Biomedical subjects

Jun Yan

Publications and source records attributed to Jun Yan.

At least 73 records · Page 4Linked to original sources

PubMed2005

[A study on the sero-epidemiology of hepatitis B in Chinese population aged over 3-years old].

OBJECTIVE: To better understand and measure the impact from immunization activities over the last 10-years, we conducted a sero-epidemiological study using the remaining blood samples of a nationwide survey on Nutrition and Health in Chinese residents, in 2002. METHODS: HBsAg, anti-HBs and anti-HBc in blood samples were tested using enzyme-linked immunosorbent assay(ELISA) reagents and revised by solid phase radioimmunoassay and Abbott ELISA reagents. RESULTS: Among population older than 3 years, the prevalence rates of HBsAg, anti-HBs and hepatitis B virus(HBV) infection were 9.09%, 37.48% and 50.04% but for children between 3 and 12 year olds, they were 5.03%, 45.33% and 29.10% respectively. Among population older than 3 years, the rates of HBsAg and HBV infection in urban area were 4.61% and 43.51%, but the rates in rural area were 9.41% and 56.77% respectively while for children from 3-years to 12-years old, they rates were 2.10%, 20.45% in urban area and 8.25%, 39.22% in rural areas, respectively. CONCLUSION: Results revealed that since the hepatitis B vaccine was introduced into the expanded program on immunization(EPI) from 1992, the prevalence rates of HBsAg and HBV infection, especially in the children from 3 to 12 years of age, had obviously declined, suggesting that some changes had happened in the epidemic characters of hepatitis B in China.

Adolescent↗

PubMed2005

[Expression of thrombospondin 2 during the repair process after alkali burn injury of cornea in mice].

OBJECTIVE: To explore the expression of thrombospondin 2 (TSP2) during the repair process after alkali burn injury to cornea in mice. METHODS: Forty mice were employed in the study. The murine corneal alkali burn model was reproduced (n = 35) as experimental group (E), and the mice were randomly divided into control (C, n = 5) and experimental (E, n = 35) groups. The mice in E group were again divided into 7 sub-groups according to different time points [3, 6, 12, 24, 48, 96 and 192 postburn hours (PBHs)] with 5 mice in each sub-group. HE staining, immunocytochemistry (ICC) and RT-PCR were employed to observe the expression of TSP2 in the corneal tissue of mice in both control and all animals in experimental sub-groups at all above mentioned time points (PBHs). RESULTS: TSP2 was expressed in corneal tissue in both C and E groups, especially in the basal layer of epithelial layer, and also a weak expression in substantia propria layer. Compared with that in C group (0.48 +/- 0.15), the expression of TSP2 in E group enhanced at 3 PBH, peaked at 6 PBH, (1.54 +/- 0.45, P < 0.05), dropped to the nadir at 24 PBH (0.73 +/- 0.19), and bounded back afterwards. It peaked again at 96 PBH (1.79 +/- 0.63, P < 0.05), then decreased thereafter, and approached the control level at 192 PBH (P > 0.05). There was remarkable angiogenesis in the cornea at 24 PBH in the mice in E group. CONCLUSION: The expressions of TSP2 exhibits fluctuating changes along with the course of repair. This might be related to the compensatory process under stress condition.

Animals↗

PubMed2004

Direct oxidative cleavage of alpha- and beta-dicarbonyls and alpha-hydroxyketones to diesters with KHSO5.

Presented is a methodology to oxidatively cleave alpha-hydroxyketones and alpha- or beta-diones using the environmentally benign reagent KHSO(5), prepared easily from Oxone, to diesters in one simple transformation. In addition, we undertook a mechanistic study to provide a plausible mechanistic interpretation. These reactions may prove to be valuable alternatives to other related metal-mediated processes.

Journal Article↗

PubMed2004

Differentiation and tropic/trophic effects of exogenous neural precursors in the adult spinal cord.

The fate of exogenous neural stem cells (NSCs) in the environment of the adult nervous system continues to be a matter of debate. In the present study, we report that cells of the murine NSC clone C17.2, when grafted into the lumbar segments of the spinal cord of adult rats, survive and undergo partial differentiation. C17.2 cells migrate avidly toward axonal tracts and nerve roots and differentiate into nonmyelinating ensheathing cells. Notably, C17.2 cells induce the de novo formation of host axon tracts aiming at graft innervation. Differentiation and inductive properties of C17.2 cells are independent of the presence of lesions in the spinal cord. The tropic/trophic interactions of C17.2 NSCs with host axons, the avid C17.2 cell-host axon contacts, and the ensheathing properties of these cells are related to their complex molecular profile, which includes the expression of trophic cytokines and neurotrophins such as glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor, glial growth factor receptors such as ErbB-2; and PASK, the mammalian homologue of the fray gene that is involved in axon ensheathment. These results show that NSCs might not only play a critical supportive role in repairing axonal injury in the adult spinal cord but also can be used as probes for exploring the molecular underpinnings of the regenerative potential of the mature nervous system after injury.

Animals↗

PubMed2004

Hypoglycemic and hypolipidemic effects and antioxidant activity of fruit extracts from Lycium barbarum.

The hypoglycemic and hypolipidemic effects of Lycium barbarum fruit water decoction, crude polysaccharide extracts (crude LBP), and purified polysaccharide fractions (LBP-X) in alloxan-induced diabetic or hyperlipidemic rabbits were investigated through designed sequential trials and by measuring blood glucose and serum lipid parameters. Total antioxidant capacity was also assessed using trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) assay. It was found that the three Lycium barbarum fruit extracts/fractions could significantly reduce blood glucose levels and serum total cholesterol (TC) and triglyceride (TG) concentrations and at same time markedly increase high density lipoprotein cholesterol (HDL-c) levels after 10 days treatment in tested rabbits, indicating that there were substantial hypoglycemic and hypolipidemic effects. Hypoglycemic effect of LBP-X was more significant than those of water decoction and crude LBP, but its hypolipidemic effect seemed to be weaker. Total antioxidant capacity assay showed that all three Lycium barbarum extracts/fractions possessed antioxidant activity. However, water and methanolc fruit extracts and crude polysaccharide extracts exhibited stronger antioxidant activity than purified polysaccharide fractions because crude extracts were identified to be rich in antioxidants (e.g., carotenoids, riboflavin, ascorbic acid, thiamine, nicotinic acid). Lycium barbarum polysaccharides (glycocojugates), containing several monosaccharides and 17 amino acids, were major bioactive constituents of hypoglycemic effect. Both polysaccharides and vitamin antioxidants from Lycium barbarum fruits were possible active principles of hypolipidemic effect.

Animals↗

PubMed2004

Corticofugal shaping of frequency tuning curves in the central nucleus of the inferior colliculus of mice.

Plasticity of the auditory cortex can be induced by conditioning or focal cortical stimulation. The latter was used here to measure how stimulation in the tonotopy of the mouse primary auditory cortex influences frequency tuning in the midbrain central nucleus of the inferior colliculus (ICC). Shapes of collicular frequency tuning curves (FTCs) were quantified before and after cortical activation by measuring best frequencies, FTC bandwidths at various sound levels, level tolerance, Q-values, steepness of low- and high-frequency slopes, and asymmetries. We show here that all of these measures were significantly changed by focal cortical activation. The changes were dependent not only on the relationship of physiological properties between the stimulated cortical neurons and recorded collicular neurons but also on the tuning curve class of the collicular neuron. Cortical activation assimilated collicular FTC shapes; sharp and broad FTCs were changed to the shapes comparable to those of auditory nerve fibers. Plasticity in the ICC was organized in a center (excitatory)-surround (inhibitory) way with regard to the stimulated location (i.e., the frequency) of cortical tonotopy. This ensures, together with the spatial gradients of distribution of collicular FTC shapes, a sharp spectral filtering at the core of collicular frequency-band laminae and an increase in frequency selectivity at the periphery of the laminae. Mechanisms of FTC plasticity were suggested to comprise both corticofugal and local ICC components of excitatory and inhibitory modulation leading to a temporary change of the balance between excitation and inhibition in the ICC.

Acoustic Stimulation↗

PubMed2004

Cyclooxygenase-2 parallels invasive depth and increased MVD in transitional cell carcinoma.

To investigate the relationship between the expression of cyclooxygenase-2 (COX-2), and invasive depth and angiogenesis in human transitional cell carcinoma (TCC), the expression of COX-2 and von Willebrand factor (vWF) was detected in paraffin-embedded transitional cell carcinoma specimens from 50 patients with histologically confirmed bladder transitional cell carcinoma. Microvessels were counted and microvessel density (MVD) was calculated. The correlation between COX-2 and invasive depth, MVD and invasive depth, COX-2 and MVD were analyzed. COX-2 expression was significantly related to the invasive depth of tumors; it solely expressed in invasive TCC. The ratio of COX-2 positively stained samples in each stage correlated to the invasive stages; so did the proportion of COX-2 (+) cells in whole tumor cells. Also, MVD increased with the invasive stages of tumors and positively correlated to the invasive depth. The COX-2-positive TCC samples were highly vascular, their microvessel density was significantly higher than that of the COX-2-negative TCC samples. There was a positive correlation between MVD and COX-2 (+) cells proportion. Our findings suggested that COX-2 was positively correlated with the invasive depth and involved in the process of angiogenesis in human transitional cell carcinoma.

Carcinoma, Transitional Cell↗

PubMed2004

Changes of uPA and uPA-R expression in the cornea after alkali burn.

PURPOSE: To investigate the expression levels of uPA and uPA-R in corneal repair after alkali burn. METHODS: The corneal alkali burn models were established in vitro and in vivo, then immunocytochemistry (ICC) of uPA/uPA-R and image analysis and statistical evaluation were performed to determine their expression levels both in vitro and in vivo. RESULTS: Compared with control group, the expressions of uPA and uPA-R after alkali burn had no significant increases till 6h, then increased rapidly from 12h to 24h and reached their maxima at 24h. From 24h, their expression levels decreased rapidly. In vivo, they rebounded again after 48h and attained their second peaks at 96h, respectively. After that, their expressions decreased again. The uPA-positive reaction mainly distributed in the cytoplasm while that of uPA-R mostly distributed on the cellular membrane. Their expression changes were similar to each other, both in vivo and in vitro. In vivo, uPA and uPA-R expressed and gathered in the basal layer of corneal epithelium. CONCLUSIONS: These results suggest that the time phase of 24h after wound is the typical stage associating with the expressional maximum of uPA and uPA-R both in vivo and in vitro. Furthermore, the results also imply that the expression changes of uPA and uPA-R correlate to the wound healing after the corneal alkali burn, uPA and uPA-R coordinate with each other to stimulate the wound healing.

Animals↗

PubMed2004

Mechanism by which orally administered beta-1,3-glucans enhance the tumoricidal activity of antitumor monoclonal antibodies in murine tumor models.

Antitumor mAb bind to tumors and activate complement, coating tumors with iC3b. Intravenously administered yeast beta-1,3;1,6-glucan functions as an adjuvant for antitumor mAb by priming the inactivated C3b (iC3b) receptors (CR3; CD11b/CD18) of circulating granulocytes, enabling CR3 to trigger cytotoxicity of iC3b-coated tumors. Recent data indicated that barley beta-1,3;1,4-glucan given orally similarly potentiated the activity of antitumor mAb, leading to enhanced tumor regression and survival. This investigation showed that orally administered yeast beta-1,3;1,6-glucan functioned similarly to barley beta-1,3;1,4-glucan with antitumor mAb. With both oral beta-1,3-glucans, a requirement for iC3b on tumors and CR3 on granulocytes was confirmed by demonstrating therapeutic failures in mice deficient in C3 or CR3. Barley and yeast beta-1,3-glucan were labeled with fluorescein to track their oral uptake and processing in vivo. Orally administered beta-1,3-glucans were taken up by macrophages that transported them to spleen, lymph nodes, and bone marrow. Within the bone marrow, the macrophages degraded the large beta-1,3-glucans into smaller soluble beta-1,3-glucan fragments that were taken up by the CR3 of marginated granulocytes. These granulocytes with CR3-bound beta-1,3-glucan-fluorescein were shown to kill iC3b-opsonized tumor cells following their recruitment to a site of complement activation resembling a tumor coated with mAb.

Adjuvants, Immunologic↗

PubMed2004

Autostereoscopic three-dimensional display based on a micromirror array.

A novel approach for three-dimensional (3-D) display systems implemented with a micromirror array was proposed, designed, realized, and tested. The major advantages of this approach include the following: (1) micromirrors are reflective and hence achromatic (panchromatic), (2) a wide variety of displays can be used as image sources, and (3) time multiplexing can be introduced on top of space multiplexing to optimize the viewing zone arrangements. A two-view (left and right) 3-D autostereoscopic display system was first constructed. Left- and right-eye views in the forms of both still and motion 3-D scenes were displayed, and viewers were able to fuse the stereo information. A multiview (two left and two right) 3-D autostereoscopic display system was then simulated.

Journal Article↗

PubMed2004

Estimating equations for association structures.

This paper investigates generalized estimating equations for association parameters, which are frequently of interest in family studies, with emphasis on covariance estimation. Separate link functions are used to connect the mean, the scale, and the correlation to linear predictors involving possibly different sets of covariates, and separate estimating equations are proposed for the three sets of parameters. Simulations show that the robust 'sandwich' variance estimator and the jackknife variance estimator for the correlation parameters are generally close to the empirical variance for the sample size of 50 clusters. The results contradict Ziegler et al. and Kastner and Ziegler, where the 'sandwich' estimator obtained from the software MAREG was shown to be unsuitable for practical usage. The problem appears to arise because the MAREG variance estimator does not account for variability in estimation of the scale parameters, but may be valid with fixed scale. We also find that the formula for the approximate jackknife variance estimator in Ziegler et al. is deficient, resulting in systematic deviations from the fully iterated jackknife variance estimator. A general jackknife formula is provided and performs well in numerical studies. Data from a study on the genetics of alcoholism is used to illustrate the importance of reliable variance estimation in biomedical applications.

Alcoholism↗

PubMed2004

[Total repair of atrioventricular septal defect with tetralogy of Fallot or Fallot's type double outlet right ventricle].

OBJECTIVE: To summarize the experience in total repair of atrioventricular septal defect with tetralogy of Fallot or Fallot's type double outlet right ventricle. METHODS: Ten patients with atrioventricular septal defect associated with tetralogy of Fallot or Fallot's type double outlet right ventricle underwent repair between June 2000 and September 2002. Atrioventricular septal defect was repaired with a 2-patch technique. The ventricular patch material was dacron artificial vascular patch, autologous pericardium was used to close the ostium of atrial septal defect after repair of the atrioventricular valve. Closure of ventricular septal defect (VSD) necessitated a combined right atrial and right ventricular approach. Each patient underwent an extensive infundibulectomy performed through the right ventriculotomy. If the pulmonary valve was more than 1 mm or 2 mm in diameter, smaller than the normal size, a transannular pericardial patch was used. If abnormal coronary arteries existed in the surface of right ventricular outflow, a homograft was used to connect the right ventricle with pulmonary artery. RESULTS: There was one death (10%) six months after repair. Two patients were not able to be extubated from ventilator because of residual VSD. After repairing the residual VSD, one patient was extubated from ventilator. The other still wasn't able to be extubated from ventilator due to right diaphragm paralysis. After folding right diaphragm, the patient got stable recovery. CONCLUSION: Atrioventricular septal defect with tetralogy of Fallot or Fallot's type double outlet right ventricle can be corrected with low mortality. Residual VSD can severely affect recovery. Long-term results need to be followed up.

Adolescent↗

PubMed2004

LFIRE-1/HFREP-1, a liver-specific gene, is frequently downregulated and has growth suppressor activity in hepatocellular carcinoma.

We have previously identified several novel genes, which are differentially expressed among human normal liver and hepatocellular carcinomas (HCCs). The full-length liver fibrinogen-related gene-1 (LFIRE-1) cDNA was cloned from the human normal liver cDNA library. LFIRE-1 is highly homologous to HFREP-1 with discrepancy at 5' untranslated region (UTR) and encodes the same fibrinogen-related protein, which suggest that these two sequences might be alternative splicing forms of the same gene, LFIRE-1/HFREP-1, located at human chromosome 8p22. The LFIRE-1 and HFREP-1 are specifically expressed in normal human liver tissue, but reduced or undetectable in most of HCC specimens at both RNA and protein level. Furthermore, the reduction or nonexpression of LFIRE-1/HFREP-1 is significantly associated with the degree of tumor differentiation. Loss of heterozygosity (LOH) analysis revealed allelic loss of LFIRE-1/HFREP-1 on chromosome 8p22 in 57.1% (24/42) of HCC specimens. We detected three inactivation mutations among 45 cases of HCC specimens examined, two of which lost the remaining allele and the third had a replacement of conserved cysteine residue with glycine residue. Notably, the downregulation of LFIRE-1/HFREP-1 expression is frequently associated with allelic loss. The reduction of LFIRE-1/HFREP-1 expression by antisense approach enhances cancer cell proliferation and colony formation in soft agar. Moreover, restoration of exogenous wild-type LFIRE-1/HFREP-1 expression but not LFIRE-1/HFREP-1 missense mutations in human HCC cells inhibited their anchorage-dependent or -independent growth in vitro, and suppressed their tumorigenicity in nude mice. In conclusion, our data demonstrated that liver-specific gene LFIRE-1/HFREP-1 was frequently downregulated and might possess growth suppressor activity in HCC.

5' Untranslated Regions↗

PubMed2004

Identification of a novel protein complex containing annexin A4, rabphilin and synaptotagmin.

Rabphilin is a synaptic vesicle-associated protein proposed to play a role in regulating neurotransmitter release. Here we report the isolation and identification of a novel protein complex containing rabphilin, annexin A4 and synaptotagmin 1. We show that the rabphilin C2B domain interacts directly with the N-terminus of annexin A4 and mediates the co-complexing of these two proteins in PC12 cells. Analyzing the cellular localisation of these co-complexing proteins we find that annexin A4 is located on synaptic membranes and co-localises with rabphilin at the plasma membrane in PC12 cells. Given that rabphilin and synaptotagmin are synaptic vesicle proteins involved in neurotransmitter release, the identification of this complex suggests that annexin A4 may play a role in synaptic exocytosis.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Cross-sectional study of cardiovascular effects of carbon disulfide among Chinese workers of a viscose factory.

OBJECTIVE: This cross-sectional study investigates the cardiovascular effects among Chinese workers who were occupationally exposed to carbon disulfide (CS2), and evaluates the protective value of the current Chinese Maximum Allowable Concentration (MAC) of CS2 against cardiovascular effects. METHODS: The measurements of exposure were performed by personal sampling and gas chromatography. The biological monitoring was performed by HPLC. Three hundred and sixty-seven exposed workers and 125 reference workers (never exposed to CS2,) were included in this study. The exposed workers were divided into 2 sub-groups according to their cumulative exposure indices, the cut-off point being at 100 which means 10 years exposure to the Chinese Maximum Allowable Concentration in the workplace (10 mg/m3). All subjects were examined using a self-administered questionnaire including medical and job history, clinical complaints in the previous three months, and underwent a clinical check-up and a 12 lead electrocardiography (ECG) at rest, coded according to the Minnesota code. Blood pressure (BP) was recorded and blood samples were collected for lipid measurements. RESULTS: The personal monitoring showed that the exposures levels (15.47 +/- 2.34 mg/m3) were below the Threshold Limit Value (TLV, 31 mg/m3), and most of the samples analyzed still showed higher values than the Chinese MAC (10 mg/m3). Clinical complaints and abnormal electrocardiograms were not significantly increased in exposed workers. No significant effect of CS2 on blood pressure, cholesterol, HDL and LDL cholesterol or triglycerides was found. Further studies are recommended to elucidate the mechanism of cardiac intoxication after CS2 exposure. CONCLUSION: This study showed that Chinese workers exposed to CS2 did not have more clinical complaints, nor more ECG abnormalities than controls and no adverse effects were found in their lipids at an exposure level below the current TLV. The present results indicate that differences of health effects reported worldwide are possibly due to different exposure levels. They also indicate that the current Chinese MAC (10 mg/m3) sufficiently protects workers against negative cardiovascular effects.

Adolescent↗

PubMed2004

Borrelia burgdorferi changes its surface antigenic expression in response to host immune responses.

The Lyme disease spirochete, Borrelia burgdorferi, causes persistent mammalian infection despite the development of vigorous immune responses against the pathogen. To examine spirochetal phenotypes that dominate in the hostile immune environment, the mRNA transcripts of four prototypic surface lipoproteins, decorin-binding protein A (DbpA), outer surface protein C (OspC), BBF01, and VlsE, were analyzed by quantitative reverse transcription-PCR under various immune conditions. We demonstrate that B. burgdorferi changes its surface antigenic expression in response to immune attack. dbpA expression was unchanged while the spirochetes decreased ospC expression by 446 times and increased BBF01 and vlsE expression up to 20 and 32 times, respectively, under the influence of immune pressure generated in immunocompetent mice during infection. This change in antigenic expression could be induced by passively immunizing infected severe combined immunodeficiency mice with specific Borrelia antisera or OspC antibody and appears to allow B. burgdorferi to resist immune attack.

Animals↗

PubMed2004

Clinical application of bidirectional Glenn shunt with off-pump technique.

A study was conducted to evaluate the outcomes of the bidirectional Glenn shunt technique performed off-pump. Between April 1999 and April 2001, 36 patients underwent bidirectional Glenn shunt, unilateral in 28 patients and bilateral in 8 patients, without using cardiopulmonary bypass. The patients consisted of 25 males and 11 females with a mean age of 5.7 +/- 5.4 years and a mean body surface area of 0.72 +/- 0.34 m2. Preoperative percutaneous oxygen saturation was 75% +/- 7%, and pulmonary arterial pressure was 14.3 +/- 3.6 mmHg. There was no operative mortality. Chylothorax occurred in 1 patient in the early postoperative period. All the other patients were discharged without complications. Mean arterial oxygen saturation at discharge was 92.7% +/- 4.0%. This shunt technique is easy to perform and is helpful in the early management of patients with a functionally univentricular heart. However, much remains to be learned about this unusual physiological system.

Adolescent↗

PubMed2004

Predication of Fhhh potential in PTA wastewater treatment.

Ebis is the intelligent environmental biotechnological informatics software developed for judging the effectiveness of the microorganism strain in the industrial wastewater treatment system(IWTS) at the optimal status. The parameter, as the objective function for the judgment, is the minimum reactor volume(Vmin) calculated by Ebis for microorganism required in wastewater treatment. The rationality and the universality of Ebis were demonstrated in the domestic sewage treatment system(DSTS) with the data published in USA and China at first,then Fhhh strain's potential for treating the purified terephthalic acid(PTA) was proved. It suggests that Ebis would be useful and universal for predicating the technique effectiveness in both DSTS and IWTS.

Forecasting↗