Biomedical subjects

Jun Yan

Publications and source records attributed to Jun Yan.

At least 109 records · Page 6Linked to original sources

PubMed2003

Analysis of parental strain DNA fragments existing in GEMs-Fhhh.

There were 6 target DNA fragments of the three parental strains existing in the cell of GEMs (genetically engineered microorganism strain) Fhhh measured in this research by PCR(polymerase chain reaction). The determination showed that GEMs Fhhh contained all the 6 target DNA fragments, mnp1, mnp2, lip1, lip2, FLO1 and 16S rDNA, and had the molecular genetic stability. Meanwhile the PCR production of each parental strain could only had its target DNA fragments and was different from each other. It may illustrate that the technique of the inter-kingdom protoplast fusion for the construction of GEMs Fhhh through the process of intercellular gene recombination could be used as a reliable bioengineering technique to create the specific functional stain for the pollution control.

Bacteria↗

PubMed2003

[Degradation kinetics for Fhhh strain in PTA wastewater].

Degradation kinetics of the purified terephthalic acid (PTA) petrochemical wastewater with the functional strain Fhhh was conducted in this research. Inputting the values of the 6 kinetics parameters obtained from the test, the values of the natural parameter and the values of the standard parameters for discharging wastewater into the environmental biotechnological informatics software (Ebis), the minimum reactor volume (Vmin) required and the specific degradation rate (qA) were calculated based on the activated sludge process. The minimum value of Vmin was 1309 m3 as well as the highest value of qA was 0.0136 h-1 among the Fhhh preparations kept in three different methods. The highest value of Fhhh qA was 4 fold of that of the native bacterium YZ1, and higher than that of the data published by 4 researchers and lower than that of by 2 researchers. The results show that Fhhh has the obvious potential for the degradation of PTA wastewater.

Biodegradation, Environmental↗

PubMed2003

[Study on protective action of lycium barbarum polysaccharides on DNA imparments of testicle cells in mice].

To investigate the protective effect of lycium barbarum polysaccharides (LBP) on DNA oxidative damage of testicle cells induced by hydrogen peroxide (H2O2). The single cell gel electrophoresis(SCGE) was used to detect the breakage of DNA strand and analyze LBP protection against oxidation damage in testicle cells treated by different concentrations of LBP for 1 hour firstly, and then cultured with 100 mumol/L H2O2 for 25 min. The results showed that a certain moment action by H2O2 could induce the breakage of DNA strand. The pretreatment of LBP (50, 100, 200, 400 micrograms/ml) significantly decreased the frequencies of cells with tail moment and the tail length of testicle cells treated by H2O2. It is suggested that LBP itself could not cause the oxidation damage, but it could clean out the free-radical and restrain the DNA damage of testicle cells caused by the oxidative stress.

Animals↗

PubMed2002

Cyclooxygenase-2 increased the angiogenic and metastatic potential of tumor cells.

It seems certain that COX-2 is related to tumor and some data suggested that COX-2 might have relation to tumor malignance and angiogenesis. In order to elucidate the relationship between COX-2 and tumor invasive and angiogenic ability, we transfected human transitional cell carcinoma (TCC) cell line, EJ, permanently with a COX-2 expression vector or the mock vector. The EJ-COX(2) cells, which overexpressed COX-2, acquired increased invasiveness and angiogenic ability by activation of VEGF, uPA, and MMP-2. Increased invasiveness and angiogenic ability were reversed by treatment with either selective COX-2 inhibitor, NS-398, or dual COX inhibitor, indomethacin. These results demonstrate that overexpression of COX-2 can lead to phenotypic changes that alter the metastatic and angiogenic potential of TCC cancer cells.

Carcinoma, Transitional Cell↗

PubMed2002

[Correction of total anomalous pulmonary venous connection in infant less than one year old].

OBJECTIVE: To evaluate the effects of early correction for total anomalous pulmonary venous connection (TAPVC) in infant under one. METHODS: Twenty-eight infants less than one year old with TAPVC were admitted and prepared to be treated surgically from July 1995 to August 2001. Total correction was performed on 24 cases, 20 males and 4 females, aged 6.04 +/- 3.34 months, with the mean body weight of 5.74 +/- 1.22 kg, of which 10 (41.67%) being of supracardic type, 11 (45.83%) being of intracardiac type, 1 (4.17%) being of infracardiac type, and 2 (8.33%) being of mixed type. Four patients died of hypoxic attack during anteoperative preparation and failed to be operated upon. RESULTS: Three infants (12.5%) died within 30 days after operation. One case of intracardiac type died of circulatory failure because of severe postoperative bleeding and late exploratory thoracotomy. One case of supracardiac type died of cardiac sufficiency because of bleeding at anastomotic stoma during operation. One case of mixed type died of circulatory failure because of high pressure of left cardiac atrium. All of the 4 cases who underwent emergent operation survived. The most common complication was arrhythmia (41.67%). CONCLUSION: The early effect of early correction for TAPVC is satisfactory and its long-term effect is to be observed. A wide anastomosis between the posterior wall of the left atrium and common pulmonary vein is more important for the supracardic type. The diameters of left atrium, left ventricle and atrial septum defect have little effect on operative results. Arrhythmia after operation has no significant increase in supracardic type through. With rather high incidence rate of arrhythmia (5/8, 62.5%), the combined left atrium incision and right atrium incision approach assures a sufficiently large incision for the supracardiac type. However, this approach is statistically different in the incidence rate of arrhythmia only between supracardiac type and intracardiac type.

Cardiac Surgical Procedures↗

PubMed2002

Expression of beta-1,4-galactosyltransferase II and V in rat injured sciatic nerves.

Beta-1,4-Galactosyltransferases II and V (beta-1,4-GalT II and V) are involved in the biosynthesis of N-linked oligosaccharides as beta-1,4-GalT I which plays important roles in promoting neuron outgrowth. In the present paper, it was illustrated that beta-1,4-GalT II and V were localized mainly in Schwann cells of lesion sciatic nerves by in situ hybridization. Northern blot showed that the expression of beta-1,4-GalT II increased gradually at both stumps of injured nerves, while that of beta-1,4-GalT V decreased at proximal stumps but increased and reached its peak on the third day post-operation at distal stumps, before it declined. The different expression of beta-1,4-GalT II and V in Schwann cells suggested that they would affect the different galactosylation of glycoproteins in injured nerves regeneration.

Animals↗

PubMed2002

Theoretical investigation of the increase in the Rosseland mean opacity for hot dense mixtures.

Based on a detailed configuration accounting model with the term structures treated by the unresolved transition array model, a large scale calculation has been performed for the opacities of medium- and high-Z materials and mixtures. Agreement between our calculated results and previous theoretical simulations is obtained. By filling in the low-opacity regions of one material with the high-opacity regions of other materials, the Rosseland mean opacity of their combination will be increased. This should be of great interest to hohlraum design in indirect-drive inertial confinement fusion. Based on our studies, many mixtures, such as Au+Nd, or Ho+Sn, can result in a similar (or higher) increase in the Rosseland mean as the previously proposed Au+Gd mixture.

Journal Article↗

PubMed2002

Autoreactive T cells revealed in the normal repertoire: escape from negative selection and peripheral tolerance.

Self-reactive T cells are known to be eliminated by negative selection in the thymus or by the induction of tolerance in the periphery. However, developmental pathways that allow self-reactive T cells to inhabit the normal repertoire are not well-characterized. In this investigation, we made use of anti-small nuclear ribonucleoprotein particle (snRNP) Ig transgenic (Tg) mice (2-12 Tg) to demonstrate that autoreactive T cells can be detected and activated in both normal naive mice and autoimmune-prone MRL lpr/lpr mice. In contrast, autoreactive T cells of nonautoimmune Tg mice are tolerized by Tg B cells in the periphery. In adoptive transfer studies, autoreactive T cells from MRL lpr/lpr mice can stimulate autoantibody synthesis in nonautoimmune anti-snRNP Tg mice. Transferred CD4 T cells migrate to regions of the spleen proximal to the B cell follicles, suggesting that cognate B cell-T cell interactions are critical to the autoimmune response. Taken together, our studies suggest that anti-snRNP B cells are important APCs for T cell activation in autoimmune-prone mice. Additionally, we have demonstrated that anti-snRNP B cell anergy in nonautoimmune mice may be reversed by appropriate T cell help.

Animals↗

PubMed2002

Identification of interaction between MEK2 and A-Raf-1.

Mitogen-activated protein (MAP) kinases are activated by dual-specificity kinases, termed MEKs. Using MEK2 as bait in yeast two-hybrid screening, besides c-Raf and KSR, A-Raf was identified as a novel partner that interacts with MEK2. This interaction was confirmed by in vitro binding assay. Further investigation indicates that regions critical for this interaction were located between residues 255 and 606 that represent the kinase domain of A-Raf.

Binding Sites↗

PubMed2002

Place-cell impairment in glutamate receptor 2 mutant mice.

There is a strong correlation between Hebbian, NMDA receptor-dependent long-term potentiation (LTP), place-cell firing, and learning and memory. We made glutamate receptor 2 (GluR2) null mutant mice that show enhanced non-Hebbian LTP in hippocampal CA1 neurons and impaired performance in a spatial learning task. We concluded that in vivo hippocampal place cells of GluR2 mutant mice were functionally impaired because (1) only 22.6% of CA1 neurons showed place fields in GluR2 mutant mice, which was significantly lower than that (43.8%) in wild-type mice; (2) GluR2 mutant place fields were much less precise; and (3) GluR2 mutant place fields were extremely unstable. Our data suggest that place cells of GluR2 knock-out mice did not form robust place fields, and that enhanced non-Hebbian LTP might play a negative role in their formation.

Action Potentials↗

PubMed2002

Different effects of p58PITSLRE on the apoptosis induced by etoposide, cycloheximide and serum-withdrawal in human hepatocarcinoma cells.

Minimal overexpression of the p58PITSLRE protein kinase in Chinese hamster ovary cells induces telephase delay, abnormal cytokinesis, retarded cell growth and apoptosis. Fas mediated T cell death is correlated with p58PITSLRE proteolysis and an increase in its histone H1 kinase activity. In this study, it was found that p58PITSLRE had different effects on the apoptosis induced by etoposide, cycloheximide and serum-withdrawal in human hepatocarcinoma cells. The ectopic expression of p58PITSLRE in human hepatocarcinoma cells suppressed apoptosis induced by etoposide, while enhancing the apoptosis induced by cycloheximide and serum-withdrawal respectively. Elevated expression of p58PITSLRE was found during the apoptosis induced by etoposide, whereas most of p58PITSLRE was proteolytically processed during apoptosis induced by cycloheximide and serum-withdrawal. Furthermore, transient transfection of p50PITSLRE resembling the proteolytic form of p58PITSLRE enhanced the 7,721 cells susceptibility to apoptosis induced by all the three stimuli. These findings suggest that the full-length p58PITSLRE might protect the cells from the apoptosis induced by etoposide and its proteolysis might contribute to and enhance the apoptosis induced by cycloheximide and serum-withdrawal respectively.

Apoptosis↗

PubMed2002

Cloning and characterization of a mouse liver-specific gene mfrep-1, up-regulated in liver regeneration.

Human fibrinogen-related protein-1/liver fibrinogen-related protein-1 (HFREP-1/LFIRE-1), a liver-specific protein, is a member of fibrinogen superfamily that exerts various biological activities. However, the function of HFREP-1/LFIRE-1 in liver remains unknown. Here we isolated its mouse ortholog gene-mouse fibrinogen-related protein-1 (mfrep-1), which encoded 314 amino acids, exhibiting 80.4% similarity to HFREP-1/LFIRE-1. Northern blot analysis revealed that 1.2-kb mfrep-1 mRNA was detected selectively in mouse liver. To explore the function of MFREP-1, we examined the levels of mfrep-1 mRNA during regeneration after 70% partial hepatectomy (PHx) in mice. mfrep-1 mRNA increased in the regenerating liver and reached the first shoulder peak at 2-4 h after PHx. Cycloheximide pretreatment could suppress the induction of mfrep-1, indicating the up-regulation of this gene need de novo protein synthesis. Its mRNA continued to elevate at 6 h thereafter and reached the second peak at 24 h. The enhanced expression of mfrep-1 maintained high until 72 h and then declined slowly to the basal level. Immunohistochemistry assessment confirmed the up-regulated expression of MFREP-1 protein in parenchymal cells during liver regeneration. These data suggested that MFREP-1 might play an important role in liver regeneration and be involved in the regulation of cell growth.

Animals↗

PubMed2002

Corticofugal modulation of midbrain sound processing in the house mouse.

An understanding of the neural mechanisms responsible for auditory information processing is incomplete without a careful examination of substantial descending pathways. This study focuses on the functional role of corticofugal projections. Our work with the house mouse reveals that the focal electrical stimulation of the primary auditory cortex leads to profound changes in auditory response properties in the central nucleus of the inferior colliculus of the midbrain. Cortical stimulation does not impact on the collicular best frequencies when the best frequencies of stimulated cortical neurons and recorded collicular neurons are similar. Rather, collicular best frequencies are shifted toward the stimulated cortical best frequencies when cortical and collicular frequencies are different. Such a shift is unrelated to the differences in minimum thresholds between cortical and collicular neurons. In addition to frequency-specific shifts in collicular best frequencies, cortical stimulation elevates collicular minimum thresholds and reduces both dynamic ranges and response magnitudes if cortical and collicular best frequencies are different. If cortical and collicular best frequencies are similar but minimum thresholds are different, collicular minimum thresholds are shifted toward the stimulated cortical thresholds; dynamic ranges and response magnitudes may either increase or decrease in this scenario. Our results suggest that the corticofugal adjustment has a centre-surround organization with regard to both cortical best frequencies and cortical minimum thresholds. The midbrain processing of sound components in the centre of cortical feedback is largely enhanced while processing in the surround is suppressed.

Acoustic Stimulation↗

PubMed2002

Cross-sectional study of the ophthalmological effects of carbon disulfide in Chinese viscose workers.

This article presents cross-sectional investigation results of ophthalmological effects for the occupational exposure to carbon disulfide of workers at a large viscose fibre factory in the middle part of China. The total of 271 exposed subjects (191 males, 80 females) and 133 workers (93 males, 40 females) not exposed to any toxic agent in the working environment underwent ophthalmological examination. The self-administered questionnaire collected data on the medical history and ophthalmological complaints during the past three months. The ophthalmologic examination included routine examination for retinal capillary anomalies and and color vision with the FM 100-Hue test method. Nearly all subjects did not use respirators, smocks or aprons, gloves or other personal protective devices during work time. The average personal CS2 exposure level in the present study was 13.7-20.05 mg/m3. The FM 100-Hue test results showed that the total error scores of the exposed group, whether male or female, were higher than that of the control, the discrimination of the green and blue zones was also impaired significantly. A fundus examination showed no retinal capillary anomalies or other serious ophthalmological symptoms that may be related to effects of CS2. In conclusion, color vision was disturbed in workers exposed to CS2, at levels below the present threshold value. Reduced color discrimination may be attributed to long-term carbon disulfide exposure and suggests that health surveillance of workers exposed to carbon disulfide should include the FM 100-Hue Test as a sensitive and easy method.

Adult↗

PubMed2002

B and T cell tolerance and autoimmunity in autoantibody transgenic mice.

One hallmark of systemic lupus erythematosus (SLE) is the presence of autoantibodies directed at a diverse group of proteins of the U1/Sm small nuclear ribonucleoprotein particles (snRNP). Patients with SLE and murine models of this disease generate high titers of affinity mature, isotype-switched autoantibodies characteristic of T cell-dependent immune responses. In this investigation, we made use of anti-snRNP Ig transgenic mice (2-12 Tg) to track regulation of autoreactive B cells in normal and autoimmune-prone mice. Autoantibody studies demonstrated that the regulation of anti-snRNP B cells is intact in non-autoimmune Tg mice, but not in MRL-lpr/lpr mice. We further utilize autoreactive Tg B cells as antigen-presenting cells (APC) and individual snRNP peptides to assess the presence of autoreactive T cells in the repertoire of non-autoimmune and MRL-lpr/lpr mice. We found that Tg B cells can direct specific T cell tolerance in a non-autoimmune-prone (C57Bl/6) background, whereas the same autoantibody transgene in MRL-lpr/lpr mice drives T cell autoimmunity. Moreover, Tg B cell APC could stimulate autoreactive T cells from wild-type (non-Tg) C57Bl/6 mice, indicating a lack of tolerance induction in the absence of the autoantigenic-presenting B cells. Thus, we have defined dual roles for autoantigen-presenting B lymphocytes in stimulating self-reactive T cells that inhabit the normal repertoire or, under some conditions, providing tolerance signals.

Animals↗

PubMed2002

Fiber arrangements of cutaneous and muscular rami in cervical nerves of the rat--regarding conception of the spinal nerve stratum-structure.

Fluorescence tracers DiO and DiI were applied to compare fiber arrangements of cutaneous and muscular rami in the proximal region of anterior and posterior branches of cervical nerves. Results show that a ventrodorsal relationship of cervical nerves is observed in gross level; however, fiber arrangements of cutaneous and muscular rami differ in anterior branches according to distance from the anterior root and dorsal root ganglia. That is, the fibers have a scattering course (no ventrodorsal relationship) in distal regions. Moreover, just before entering anterior roots, the motor fibers of muscular ramus run through the ventral part and sensory fibers of muscles and fibers of cutaneous ramus run through the dorsal part and intersect with motor fibers of the posterior muscular ramus. In contrast with the anterior one, in posterior branches of cervical nerves, cutaneous and muscular rami fibers are very regularly arranged in the distal and proximal region. Based on these results, the ventrodorsal relationship of fiber arrangements could exist in posterior branches and proximal region of anterior branches. Present results differ with those of the spinal nerve stratum-structure; therefore, they are insufficient to elucidate the relationship of peripheral nerves by conception of spinal nerve stratum-structure.

Animals↗

PubMed2002

Distribution of sensory neurons of ventral and dorsal cervical cutaneous nerves in dorsal root ganglia of adult rat--a double-label study using DiO and DiI.

To examine distribution of sensory neurons of ventral and dorsal cervical cutaneous nerves in dorsal root ganglia (DRGs), DiO and DiI tracers were applied at the proximal section of nerves (transverse superficial cervical and anterior supraclavicular nerves were selected as ventral cervical cutaneous nerves; dorsal cutaneous branches of second, third and fourth cervical nerves were selected as dorsal cervical cutaneous nerves). Located distributions were observed in DRGs of C2, C3, and C4 (25/46 DRGs). Sensory neurons of the ventral cervical cutaneous nerves were distributed in dorso-lateral or dorso-medial portions; neurons of dorsal cervical cutaneous nerves were distributed in ventro-medial or ventro-lateral portions of DRGs. Moreover, sensory neurons of transverse superficial cervical and anterior supraclavicular nerves were mainly distributed from the caudal half of C2 to whole part of C4 DRGs. Results show that there is a tendency for located distribution in two group sensory neurons; also, sensory neurons of ventral cervical cutaneous nerves have a segmental distribution, which has been verified in the brachial and lumbar plexus.

Age Factors↗

PubMed2002

[Surgical treatment of aorta-pulmonary window].

OBJECTIVE: To summarize the experience of surgical treatment of aorta-pulmonary window. METHODS: Between January 1980 and August 2000, 18 patients suffering from aorta-pulmonary window, 11 males and 7 females, with a mean age of 6.5 years (2 approximately 14 years), underwent surgical treatment. Eleven cases were type I, 3 were type II and 4 were type III. Sixteen patients underwent surgical repair under cardiopulmonary bypass at moderate hypothermic temperatures. Deep hypothermic circulatory arrest was used in 2 of them. Closed surgical ligation under cardiopulmonary bypass at normal thermic temperature was performed on 1 case. External division and ligation under general anesthesia through left thorax was performed on 1 case. Thirteen patients underwent surgical repair through the anterior wall of aorta. Surgical repair was performed through the anterior wall of pulmonary artery in 3 cases. Other associated malformations were repaired simultaneously. RESULTS: Three patients died during the peri-operative period. Fifteen patients who survived the operation were followed up for 108 months on average. One patient was noted to have residue shunt on aorta pulmonary window. The other patients showed alleviation of symptoms and improvement of life quality. CONCLUSION: Early diagnosis, suitable surgical procedure and prevention and treatment of postoperative complications are the key factors for treatment of aorta pulmonary window.

Adolescent↗