Biomedical subjects

Yong Liu

Publications and source records attributed to Yong Liu.

At least 55 records · Page 3Linked to original sources

PubMed2006

Cell proliferation in ependymal/subventricular zone and nNOS expression following focal cerebral ischemia in adult rats.

Neuronal nitric oxide synthase (nNOS) regulates neurogenesis in normal developing brain, but the role of nNOS in neurogenesis in the ischemic brain remains unclear. To investigate the temporal and spatial relationship between cell proliferation of the ependymal/subventricular zone (SVZ), a principal neuroproliferative region in the adult brain, and nNOS expression, the male Sprague-Dawley rats weighing 250-350 g were used. The focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO). 10 microl of 0.2% fluorescence dye DiI was injected into the right lateral ventricle to prelabel ependymal/subventricular zone cells before ischemia. The rats were killed immediately after ischemia and days 1, 3, 7, 11, 14, 21 and 28 after ischemia. DiI-labeled cell counting was employed to assess cell proliferation. Immunohistochemistry and grayscale analysis were performed to determine nNOS localization and its quantity in the specific regions. Compared with control, the density of DiI-labeled cells in the ipsilateral ependyma/SVZ was significantly higher at days 1, 3, 7 and 11 after ischemia, whereas the quantity of nNOS expression in the ependyma/SVZ adjacent regions was significantly lower at the above time points. Additionally, nNOS positive cells were largely excluded from SVZ, and their long processes did not enter the ependyma/SVZ. Our results indicate that after focal cerebral ischemia, decreased nNOS expression in the ipsilateral ependymal/SVZ adjacent regions might be related to cell proliferation in the ependymal/SVZ.

Animals↗

PubMed2006

Early metabolism evaluation making traditional Chinese medicine effective and safe therapeutics.

Increasing attention is being paid to the scientific evaluation of traditional Chinese medicine (TCM). As many TCMs are capable of biotransformation in the gastrointestinal tract, attention to biotransformation of TCM in the gastrointestinal tract may lead to discovery of the active components and active mechanisms. In this article, we review reports that host metabolic enzymes and intestinal bacteria may be responsible for the metabolism of TCM. Good understanding of the in vivo course of TCM will help us to know how to conduct metabolism evaluation of TCM by using in vitro human-derived system. This evaluation system will create new views on TCM as effective and safe therapeutic agents.

Biotransformation↗

PubMed2006

Band structures of TiO2 doped with N, C and B.

This study on the band structures and charge densities of nitrogen (N)-, carbon (C)- and boron (B)-doped titanium dioxide (TiO(2)) by first-principles simulation with the CASTEP code (Segall et al., 2002) showed that the three 2p bands of impurity atom are located above the valence-band maximum and below the Ti 3d bands, and that along with the decreasing of impurity atomic number, the fluctuations become more intensive. We cannot observe obvious band-gap narrowing in our result. Therefore, the cause of absorption in visible light might be the isolated impurity atom 2p states in band-gap rather than the band-gap narrowing.

Journal Article↗

PubMed2006

[Effect of citicoline on spatial learning and memory of rats after focal cerebral ischemia].

OBJECTIVE: To investigate the effects of citicoline on spatial learning and memory of rats after focal cerebral ischemia. METHODS: The rats were randomly divided into sham-operation group, ischemia control group and citicoline group. In the later two groups, focal cerebral ischemia model was established by introducing an intraluminal filament into the left middle cerebral artery, and citicoline (500 mg/kg) or 0.9% NaCl was administered intraperitoneally once a day for 2 weeks after the operation. The rats in the sham-operation group were not subjected to middle cerebral artery occlusion (MCAO) with intraluminal filament. The spatial learning and memory functions of the rats were evaluated by Morris water maze test 15 days after MCAO for 5 days. RESULTS: The rats in ischemia control group exhibited serious spatial learning and memory deficits in both place navigation test and spatial probe test. In the former test, the mean escape latency of citicoline-treated rats were significantly shorter than that of ischemia control rats (P<0.01), and in the latter test significant diffidence was noted between citicoline and ischemia control groups in the percentage time spent in the former platform quadrant and frequency of crossing the former platform (P<0.05). CONCLUSION: Citicoline can improve the spatial learning and memory function of rats after focal cerebral ischemia.

Animals↗

PubMed2006

[Cloning, expression, and antibody preparation of nestin with immunohistochemical analysis].

OBJECTIVE: To obtain recombinant nestin and prepare anti-nestin polyclonal antibody (mAb) to explore the biological roles of nestin in the central nervous system development. METHODS: The nestin cDNA was cloned from human neural stem cells by RT-PCR and ligated to prokaryotic expression plasmid pQE30 for construction of the recombinant vector pQE30-nestin. After sequencing, the recombinant vector was transformed into E.coli M15 and His-tagged nestin was induced by IPTG. The nestin was purified by Ni-NTA affinity chromatography column and characterized by SDS-PAGE and Western blotting. BALB/c mice were immunized with the purified recombinant protein to prepare the antiserum, which was analyzed by Western blotting, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. RESULTS: The nestin gene was successfully cloned from human neural stem cells, which was identical to that reported in GenBank. After IPTG induction, the E.coli transformed with pQE30-nestin plasmid expressed a 25,000 His-tagged protein, which was successfully purified and identified as nestin by Western blotting. Western blotting, ELISA and immunohistochemistry demonstrated that the antiserum could specifically bind to the recombinant nestin as well as to nestin in fetal human and rat brains. CONCLUSION: We successfully cloned the nestin gene and expressed the nestin, and nestin mAb prepared can specifically recognize not only the recombinant nestin, but also nestin from human and rats brain tissues.

Adult Stem Cells↗

PubMed2006

[Screening for Y chromosomal microdeletions in AZF region with modified multiplex PCR].

OBJECTIVE: Screening for Y chromosomal microdeletions in azoospermia factor (AZF) region with modified multiplex PCR. METHODS: 160 cases with spermatogenetic failure were recruited in the experimental group, while 90 cases of donors in controls. According to the laboratory guidelines supported by European Academy of Andrology (EAA) and European Molecular Genetics Quality Network (EMQN), Y chromosomal microdeletions in AZFa, b, c regions were screened with multiplex PCR. The primers of sequence targeted sites (STSs) and conditions of PCR were modified. RESULTS: Using modified multiplex PCR, 14 (8.75%) cases with Y chromosomal microdeletions were found in the experimental group, while no case in controls. There were 12 cases in AZFc, 1 case in AZFa + b + c, 1 case in AZFb + c. According to statistics, the difference between two groups was significant (P <0.001). Reaction products could be clearly separated with agarose gel and finished in 1 h. CONCLUSION: Modified multiplex PCR protocols supported by EAA and EMQN proved to be very accurate, sensitive and quick, which could be put into screening practice for Y chromosomal microdeletions in AZF region.

Adult↗

PubMed2006

[A multicentre study on the pathogenic agents in 665 adult patients with community-acquired pneumonia in cities of China].

OBJECTIVE: To investigate the pathogenic causes of community-acquired pneumonia (CAP) in adult patients in China, the relation of previous antibiotic use and the Pneumonia Patient Outcome Research Team (PORT) classification to microbial etiology, and the prevalence of drug resistance of common CAP bacteria. METHODS: A prospective study was performed on 665 consecutive adult patients with CAP at 12 centers in 7 Chinese cities during one year. The etiology of pneumonia was considered if one of the following criteria was met: (1) valid sputum sample yielding one or more predominant strains; (2) blood cultures yielding a bacterial pathogen; (3) seroconversion, a > or = 4-fold increase or decrease titers of antibodies to Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophila. Minimum inhibitory concentration (MIC) of respiratory tract isolates was determined using the agar dilution method. RESULTS: Pathogens were identified in 324/610 patients (53.1%) with valid serum samples and sputum cultures as follows: Mycoplasma pneumoniae (126, 20.7%), Streptococcus pneumoniae (63, 10.3%), Haemophilus influenzae (56, 9.2%), Chlamydia pneumoniae (40, 6.6%), Klebsiella pneumoniae (37, 6.1%), Legionella pneumophila (31, 5.1%), Staphylococcus aureus (23, 3.8%), Escherichia coli (10, 1.6%), Moraxella catarrhalis (8, 1.3%), Pseudomonas aeruginosa (6, 1.0%). Of 195 patients with a bacterial pathogen, an atypical pathogen was identified in 62 (10.2%) cases. The non-susceptibility rate of Streptococcus pneumoniae to penicillin, azithromycin, and moxifloxacin was 20.3%, 75.4% and 4.3% respectively. CONCLUSIONS: Atypical pathogens have important role in CAP, with Mycoplasma pneumoniae being the most common pathogen, and mixed infection of atypical pathogens with bacteria was found in 10.2% of the cases. Streptococcus pneumoniae and Haemophilus influenzae remain the most important bacteria for CAP. More than 75.0% of Streptococcus pneumoniae was resistant to macrolides and 20.3% was resistant to penicillin.

Adult↗

PubMed2006

[Prospects for diagnosis of prostate cancer by biomarkers in the urine].

Prostate cancer is the most frequently diagnosed cancer in the Western male population and the second leading cause of cancer mortality. Recently many new methods are used to detect the tumor, some of which use the urine as the sample. The biomarkers in the urine will possibly improve the sensitivity and specificity to aid in prostate cancer detection.

Biomarkers, Tumor↗

PubMed2006

[Posterior continuous curvilinear capsulorhexis with optic capture of the posterior chamber intraocular lens in pediatric cataract].

OBJECTIVE: To assess the clinical effects of posterior continuous curvilinear capsulorhexis with optic capture of the posterior chamber intraocular lens in pediatric cataract. METHODS: Fifty-one cases (83 eyes) received posterior continuous curvilinear capsulorhexis with optic capture of the posterior chamber intraocular lens. Preoperative and postoperative visual acuity and refractive error were recorded. Intraoperative and postoperative complications were observed. The follow-up period was from 6 to 36 months. RESULTS: Implantation of optic capture of the posterior chamber intraocular lens was successfully performed in 75 eyes (90.4%). The mean postoperative best corrected distant visual acuity achieved 0.5 or better in 75 eyes (48.0%). No eyes with optic capture were found optic axis opaque. The major complications of optic capture were anterior chamber fibrous exudation, iris posterior synechia and lenticular precipitates. CONCLUSION: Optic capture of the posterior chamber intraocular lens is safe and effective in the treatment of pediatric cataract to posterior continuous curvilinear capsulorhexis especially in the prevention of secondary opacification from the visual axis.

Adolescent↗

PubMed2006

[Effects of external counterpulsation on shear stress and production of nitric oxide and cGMP in canines with myocardial infarction].

OBJECTIVE: To investigate the effects of external counterpulsation (ECP) on shear stress and signal transduction in canines with myocardial infarction. METHODS: Nineteen healthy dogs were randomly divided into control, ischemia, and ischemia plus ECP groups. Myocardial infarction was induced in the latter two groups by ligation of the left anterior descending artery (LAD). Serum and aorta NO levels of the dogs were determined by modified nitrate reductase method, and serum and aorta cyclic guanosine monophosphate (cGMP) levels by radioimmunoassay. RESULTS: The shear stress in the truncus brachiocephalicus decreased after LAD ligation, but increased significantly after 2 h of ECP treatment. Serum and aorta NO levels in ECP and control groups were significantly higher than those in the ischemic group (P<0.05). Serum and aorta cGMP levels in control group and ECP group after LAD ligation were also significantly higher than those in the ischemic group (P<0.05). CONCLUSION: ECP can increase the shear stress and increase NO and cGMP levels in dogs with myocardial ischemia, which might be an important mechanism of ECP for protection of the ischemic myocardium.

Animals↗

PubMed2006

[Optimal selection method of technologies of medical wastes treatment].

This paper investigate the medical wastes (MW) definition, production, characteristics and technical requirements, which is decisive for properly selecting methods for medical wastes treatment (MWT). Base on this, the advantages/disadvantages and adaptation of various treatment options are qualitatively analyzed and broadly compared. Then, four kinds of technologies, namely the thermal treatment, autoclaving, chemical disinfection, and microwave disinfection, are primarily chosen. Moreover, a hierarchy decision-making model considering the disposal status, economic level, policies and international turns is further set up. According to it, 4 proposed methods are effectively assessed. The result indicates that thermal treatment technology is the optimal choice for medical wastes treatment in Hangzhou city. Besides, the optimal selection method for medical wastes treatment is synthetically presented, which is suggested as a strong support for choosing optimal technology, and will contribute a lot to related research as well.

China↗

PubMed2006

[Multiresidue determination of organophosphorus pesticide residues in vegetables and fruit by gas chromatography-negative ion chemical ionization-mass spectrometry].

An analytical method of gas chromatography coupled with negative ion chemical ionization-mass spectrometry for simultaneous determination of nine organophosphorus pesticide residues in vegetables and fruit has been developed, and the negative ions structure and partition mechanism of the nine organophosphorus pesticides were interpreted. Meanwhile, the matrix effect for sample analysis was discussed, and matrix-matched calibration for quantification was introduced to reduce the matrix effect in this method. Pesticides were extracted from sample with ethyl acetate in an ultrasonic bath, then determined by gas chromatography-mass spectrometry operated in negative chemical ionization mode and quantified in selective ion monitoring mode, and ethion was used as an internal standard. The detection limits of the method were 0.12-1.0 microg/kg for the nine organophosphorus pesticides, and the relative coefficients were higher than 0.9993. A blank sample (tomato) was spiked at 100, 400, 800 microg/kg for each pesticide, and the recoveries were determined to be from 78% to 126% with relative standard deviations from 0.58% to 14.7% for the pesticides.

Agriculture↗

PubMed2006

Characterization of hepatic drug-metabolizing activities of Bama miniature pigs (Sus scrofa domestica): comparison with human enzyme analogs.

We used various substrates and selective inhibitors of human cytochrome P450 (CYP) isozymes as probes to study the metabolism of liver microsomes from Chinese Bama miniature pigs. Nifedipine oxidation (NOD) and testosterone 6beta-hydroxylation (6beta-OHT) activities were similar between human liver microsomes and those from Bama miniature pigs. However, compared with those from humans, liver microsomes from Bama miniature pigs showed decreased phenacetin O-deethylation, coumarin 7-hydroxylation, and chlorzoxazone 6-hydroxylation activities, whereas dextromethorphan O-demethylation activity was increased. Ketoconazole selectively inhibited NOD and 6beta-OHT activities in microsomes from Bama pigs, and 8-methoxypsoralen and tranylcypromine inhibited coumarin 7-hydroxylation in pig microsomes. However, furafylline and quinidine failed to selectively inhibit phenacetin O-deethylation and dextromethorphan O-demethylation in microsomes from Bama pigs, whereas chlormethiazole more efficiently inhibited coumarin 7-hydroxylation activity than chlorzoxazone 6-hydroxylation in pig microsomes. Our results suggest that liver microsomes from Chinese Bama miniature pigs are similar to those from humans in regard to metabolism of nifedipine and testosterone (both are probe substrates for human CYP3A4). In addition, chemical inhibitors used as specific probes for human P450 enzymes did not always show the same selectivity toward corresponding enzyme activities in liver microsomes from Bama pigs. However, ketoconazole (a potent inhibitor of human CYP3A4) could be used as a selective inhibitor probe for the NOD and 6beta-OHT activities in liver microsomes from Chinese Bama miniature pigs.

Adult↗

PubMed2006

Establishment of cell free conversion system with biotin-labelled recombinant PrPsen expressed in E. coli.

OBJECTIVE: To report a protocol using biotin-labelled PrP protein in cell free conversion assay instead of isotope. METHODS: A hamster PrP protein (HaPrP) was expressed in E. coli and purified with HIS-tag affinity chromatograph. After being labelled with biotin, HaPrP was mixed with PrPSc preparation from scrapie strain 263K. RESULTS: Protease-resistant bands were detected after four-day incubation. CONCLUSION: The new conversion model provides a reliable, easily handling, and environment-friendly method for studies of prion and transmissible spongiform encephalopathies.

Animals↗

PubMed2006

[Effect of histamine on intracortical blood vessels of rats].

OBJECTIVE: To investigate histamine-induced changes of the intracortical vessels in the cortical slice of rat brain. METHODS: Immunohistochemistry was employed to detect the expression of H1 and H2 receptors in the intracortical blood vessels of rats. Histamine-induced constriction of the intracortical blood vessels of the brain slices was observed with differential interference contrast microscope. Measurements of the luminal diameter were made on-line during the course of the experiment and confirmed off-line from the stored images. In order to observe whether histamine H1 and H2 receptors affected histamine-induced constriction, the intracortical blood vessels in the brain slices were pre-treated with H1 receptor antagonist diphenhydramine and H2 receptor antagonist cimetidine. RESULTS: Expression of H1 and H2 receptors was detected in the intracortical blood vessels of the rat brain. Histamine (1-100 micromol/L) induced a concentration-dependent constriction from (1.48-/+0.67)% to (32.91-/+7.91)%. The reactions to each histamine concentration were significantly (P<0.01) different from each other, with the exception of the highest histamine concentrations (30 and 100 micromol/L) when maximal constriction due to histamine were observed (P>0.05). With pre-treatment of the slice with 10 micromol/L diphenhydramine, application of histamine did not elicit constriction. Pre-treatment of the slice with 10 micromol/L cimetidine did not completely inhibit but somehow significantly weakened vascular constriction in response to histamine treatment at 10 and 30 micromol/L (P<0.05). CONCLUSION: Histamine can induce constriction of the intracortical blood vessels, which is mediated by H1 receptor.

Animals↗

PubMed2006

[Effects of irbesartan on nitric oxide system in the heart of diabetic rats].

OBJECTIVE: To investigate the effects of irbesartan for heart protection and on heart nitric oxide (NO) system in diabetic rats. METHODS: Thirty adult male Wistar rats were randomly divided into three equal groups, namely control group, diabetes group and irbesartan group. Streptozotocin (STZ, 50 mg/kg) was injected to the abdomen to induce diabetes in the rats. After treatment for 12 weeks, the rats were sacrificed and the urine volume, body weight, ratio of heart to body weight, plasma glucose and glycosylated hemoglobin (HbA1c) were measured. NO levels in the serum and myocardium were determined. Inducible nitric oxide synthase (iNOS) expression was determined by immunohistochemistry, and iNOS mRNA detected by RT-PCR. RESULTS: Urine volume, ratio of heart to body weight, plasma glucose, HbA1C, NO levels in the urine, blood and myocardium in diabetic and irbesartan rats were significantly greater than those of normal controls (P<0.05). The ratio of heart to body weight and NO levels of urine, serum and heart tissue in rats of irbesartan group were significantly decreased as compared with those of diabetes rats (P<0.05). Myocardium iNOS mRNA and protein expression decreased significantly in irbesartan group, but not in diabetes group. CONCLUSIONS: The abnormality in NO and iNOS mRNA expression might be related to diabetic cardiomyopathy. Irbesartan can decrease iNOS mRNA and protein expressions and reduce NO levels in STZ-induced diabetic rats.

Angiotensin II Type 1 Receptor Blockers↗

PubMed2006

[Effects of calcitonin on the pathology of spinal fusion in rabbit models].

OBJECTIVE: To observe the effect of calcitonin on the pathology of fusion in lumbar posterior/facet spinal fusion in rabbit model. METHODS: Thirty-two male New Zealand white rabbits were used to establish spinal fusion model. Sixteen rabbits received calcitonin at a dose of 1 IU x kg(-1) x d(-1) were classified as calcitonin group, and the remaining 16 rabbits as control group. Rabbits were killed 1, 2, 4, and 8 weeks after operations. Haematoxylin-eosin staining was applied to observe the pathological process of spinal fusion. Expression of bone morphogenetic protein-2 (BMP2) was detected by immunohistochemistry. RESULTS: Bone resorption and fibrovascular stroma formation were the main histological presentation 1 week after surgery. Two and 4 weeks after surgery, more cartilage formed with varying degrees of mineralization, while less trabeculae could be observed in the phase of active bone formation. No remarked margin was seen between cartilage and bone tissues. Eight weeks after surgery, trabeculae distributed widely. The pathological process of spinal fusion in calcitonin group was faster than in control group. Emery scores showed significant differences at different time points (F = 265.44, P < 0.001). Calcitonin and time had a positively synergistic effect on Emery scores, and calcitonin caused significant difference in terms of Emery scores since the second week (F = 22.43, P < 0.001). Expressions of BMP, were significantly different at different time points (F = 1186.54, P < 0.001). Also, calcitonin and time had a synergistic effect on BMP2 expression (F = 13.14, P < 0. 001). CONCLUSIONS: Endochondral ossification exists in the spinal fusion process and may be the main way of ossification. Calcitonin may stimulate the expression of BMP2 and thus accelerate the process of spinal fusion.

Animals↗

PubMed2006

[Effect of ligustrazine on cell proliferation in subventricular zone of lateral cerebral ventricle after adult rat suffering from focal cerebral ischemia].

OBJECTIVE: To explore the effect of ligustrazine on cell proliferation in subventricular zone of lateral cerebral ventricle after middle cerebral artery occluded (MACO) in adult rat. METHODS: SD male rats were randomly divided into three group: sham operation group, ischemic model group and Ligustrazine group. The model of the middle cerebral artery occlusion was established by placement of an intraluminal filament at the origin of left MCA. Ligustrazine was administered intraperitoneally with a dose of 80 mg/kg daily starting at 2 hours after MCAO. BrdU (50 mg/kg) was injected once a day intraperitoneally starting at 4 hours after operation. Number of BrdU-positive cells and expression of doublecortin (DCX) in subventricular zone (SVZ) were measured by immunohistochemistry on day 7, 14, 24 after operation. RESULTS: Compared with sham operation group, BrdU-positive cells in ischemic model group increased on day 7, reached the peak on day 14, then decreased on day 21 after operation. On day 7 and 14, the numbers of BrdU-positive cells in Ligustrazine group were markedly augmented and significantly more than those in ischemic model group (P < 0.01), but decreased on day 21. The expressions of DCX in SVZ in ischemic model group were enhanced on day 7 with lasting into day 14, and reduced on day 21, but still higher than those in sham operation group on day 7, 14, and 21, respectively. The expressions of DCX in SVZ in Ligustrazine group increased gradually along with prolong of ischemia and kept the high level up to day 21 after operation, and were higher than those in ischemic model group on day 14 and 21. CONCLUSION: Our results suggest that Ligustrazine may promote the cells of SVZ, which the adult rats suffer from the focal cerebral ischemia, to go into cell proliferation.

Animals↗