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Biomedical subjects

Hua Li

Publications and source records attributed to Hua Li.

159 records · Page 9Linked to original sources
PubMed2002

[Preliminary study of cercaria antigen of Schistosoma japonicum before and after ultraviolet irradiation].

OBJECTIVE: To study the changes in the constituents of the cercaria antigen of Schistosoma japonicum before and after ultraviolet irradiation. METHODS: The cercaria of Schistosoma japonicum were exposed to ultraviolet light (UV) irradiation at a dose of 400 mgrW/cm2 for 1 min, and the UV-irradiated cercaria antigen (UVCA) and normal cercaria antigen (NCA) were simultaneously analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. RESULTS: At least 2 antigens with relative molecular mass (Mr) of 212 000 and 82 000 were identified in UVCA but not in NCA by SDS-PAGE analysis, and the concentrations of the antigens with Mr of 116 000, 26 000 and 16 000 in UVCA were significant higher than those in NCA. On the other hand, the antigenic molecule with Mr of 67 000 in NCA was recognized by serum from pigs vaccinated with UV-attenuated cercariae, but not by serum from pigs with Schistosoma japonicum infection. Antigens with Mr of 79 000 and 94 000 were apparently more strongly reactive with the former porcine serum than with the latter. CONCLUSION: The results suggest that all the novel antigens arising from or increased by UV exposure, or antigens specifically recognized by serum from pigs vaccinated by UV-attenuated carcariae may be the principal factors in the highly protective immunity provoked by irradiated cercariae.

Animals↗
PubMed2002

In vitro amplification of Toxoplasma gondii rhoptry protein 2 gene and construction of its eukaryotic expression plasmid.

OBJECTIVE: To construct a recombinant eukaryotic expression plasmid containing rhoptry protein 2 (ROP2) gene of Toxoplasma gondii. METHOD: The truncated ROP2 gene was amplified from the genomic DNA of Toxoplasma gondii RH strain and cloned into plasmid pGEX-4T-1. The PCR product was subcloned into an eukaryotic expression plasmid pcDNA3 which was identified by enzyme digestion and PCR amplification. Sequence analysis of the insert in the recombinant plasmid was performed by Sanger's method. RESULTS: The amplified DNA fragment was about 1043 bp in length, with identical sequence with the published ROP2 gene sequence. Enzyme digestion and PCR analysis showed that the truncated ROP2 gene had been successfully cloned into plasmid pGEX-4T-1 and pcDNA3. CONCLUSION: The truncated ROP2 gene of Toxoplasma gondii has been amplified and cloned into the eukaryotic expression plasmid pcDNA3.

Animals↗
PubMed2002

[Construction and characterization of the cDNA library from Schistosoma japonicum cercariae].

OBJECTIVE: To construct a cDNA library from Schistosoma japonicum cercariae. METHODS: Total RNA was extracted from 500,000 S. japonicum cercariae and used to synthesize the double-stranded cDNA and cloned into the TriplEx2 vector using "SMART cDNA Construction Kit". RESULTS: The primary titer of the constructed cDNA library is 1.8 x 10(7) pfu/ml and the titer of amplified library is 2.5 x 10(10) pfu/ml. The average size of inserts is 1.075 kb. The recombinant efficiency is 94.4%. The full length cDNA of S. japonicum TPI and JF-2 genes was successfully amplified from the library. CONCLUSION: A cDNA library of S. japonicum cercariae has been constructed successfully.

Animals↗
PubMed2002

[Effects of soy extract on lipid metabolism in ovariectomized rats].

OBJECTIVE: To study effects of soy extract on lipid metabolims in ovariectomized rats. METHOD: 90 Wistar rats were randomly divided into 9 groups: control group, sham group, model group, estrogen group, soy isoflavone group of high dose, soy isoflavone group of low dose, soy extract of high dose, soy extract of low dose, and soy polysaccharde group, 10 rats in each group. Except fer of control and sham groups, the test rats were ovariectomized. One week after operation, the rats were treated with different drugs. Six weeks after operation, the rats were killed, with serum and liver taken, and serumglycerol(sGT), cholesterol(sGC), LDL, HDL and liver homogenate hGT, hGC, measured. RESULT: The level of sGC, LDL in ovariectmized rats increased significantly, compared with that in control and sham groups. In liver both the level of hGT and hGC were higher than that in liver from control and sham groups. Administration of estrogen or soy extract or soy isoflavone could attenuate these in ovariectomized rats, but soy polysacchardes did not have any effects. CONCLUSION: Ovariectomized rats have an imbalance of lipid metabolism, the level of hGT and hGC were increased, and administration of estrogen, soy extracts or soy isoflavone could decrease these changes induced by ovariectomizing.

Animals↗
PubMed2002

[Effects of soy extract on energy balance in ovariectomized rats].

OBJECTIVE: In order to study on effects of soy extract on energy metabolims in ovariectomized rats. METHOD: 90 Wistar rats were randomly divided into 9 groups: control group, sham group, model group, estrogen group, soy isoflavone group of high dose, soy isoflavone of low dose, soy extract of high dose, soy extract of low dose, 10 rats each group. Beside of control and sham groups, the rest rats were ovariectomized. One week after operation, the rats were treatmented with different drugs, measument of body weigh and feed weigh each week. Six week after operation, the rats were killed, serum were taken, abdomen lipid were removed and weight. RESULT: The ovariectomized rats took more food and got weight gain significantly; Body mess index(BMI), Abdomen lipid weigh and food transform rate in Model group increased significantly than control and sham groups. Administration of estrogen or soy extract or soy isoflavone could block these changes in ovariectomized rats, but soy polysaccharides did not have the effects. CONCLUSION: Ovariectomized rats have imbalance of energy metabolism, weigh gain and accumulation of abdomen lipid; administration of estrogen, soy extracts or soy isoflavone could attenuate these changes induced by ovariectomizing.

Animals↗
PubMedDate not supplied

Chemiluminescence of cobalt(II)-catalysed auto-oxidation of sulphite and its application to cobalt analysis.

The oxidation of sulphite by dissolved oxygen in aqueous solution catalysed by cobalt(II) was investigated. A weak chemiluminescence (CL) emission was observed when the reaction took place in a strong alkaline solution without any special CL reagent. Further studies showed that in the presence of fluorescein sodium the CL signal was enhanced significantly. The CL emission is linear with Co(II) concentration in the range 0.6-80 nmol/L and the detection limit is 0.3 nmol/L. In addition to Co(II), other transition metal ions were also tested, and the results showed that the proposed system was highly selective for Co(II). The method was successfully applied to the determination of Co(II) in pharmaceutical preparations. The possible CL mechanism was also discussed.

Catalysis↗
PubMedDate not supplied

Flow injection chemiluminescence determination of dihydralazine sulphate based on permanganate oxidation sensitized by rhodamine B.

A novel flow injection chemiluminescence (CL) method for the determination of dihydralazine sulphate (DHZS) is described. The method is based on the CL produced during the oxidation of DHZS by acidic permanganate solution in the presence of rhodamine B. Rhodamine B is suggested as a fluorescing compound for the energy-transferred excitation. The CL emission allows quantitation of DHZS concentration in the range 5-800 ng/mL, with a detection limit of 1.9 ng/mL (3sigma). The experimental conditions for the CL reaction are optimized and the possible reaction mechanism is discussed. The method has been applied to the determination of DHZS in pharmaceutical preparations and compares well with the high performance liquid chromatography (HPLC) method.

Acids↗
PubMedDate not supplied

Determination of tetracycline, chlortetracycline and oxytetracycline by flow injection with inhibitory chemiluminescence detection using copper(II) as a probe ion.

This paper reports an indirect flow-injection (FI) method for the determination of the tetracycline drugs (TCs), tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC), using copper(II) as a probe ion. The method was based on the inhibition caused by these TCs to the copper(II)-catalysed chemiluminescence (CL) reaction between luminol and H(2)O(2). The CL reaction was induced on-line and injection of the sample produced negative peaks as a result of the copper(II) complexation or displacement by the analytes. The height of the peaks was proportional to the drug concentration in the sample. The choice of the catalyst ion, the concentration of luminol, H(2)O(2) and copper(II) are discussed. The linear range was 3.6 x 10(-8)-1.0 x 10(-5), 1.1 x 10(-7)-1.0 x 10(-5) and 1.9 x 10(-7)-1.0 x 10(-5) mol/L for TC, CTC and OTC, respectively. The detection limit was 5.0 x 10(-9) mol/L for TC, 1.0 x 10(-8) mol/L for CTC and 2.0 x 10(-8) mol/L for OTC (3sigma), respectively. The method was applied to the determination of TCs in pharmaceutical preparations and human urine with recoveries in the range 95-105%.

Catalysis↗
PubMedDate not supplied

Changes in cPKC isoform-specific membrane translocation and protein expression in the brain of hypoxic preconditioned mice.

Previous studies have shown that the level of total conventional protein kinase C (cPKC) membrane translocation (activation) was increased in the brain of hypoxic preconditioned mice. In order to find out which isoform of cPKC may participate in the development of cerebral hypoxic preconditioning (HPC), we used Western bolt and immunohistochemistry to observe the effects of repetitive hypoxic exposure (H1-H6, n = 6 for each group) on the level of cPKC isoform-specific protein expression and its membrane translocation in the cortex and hippocampus of mice. We found that the levels of cPKC betaII and gamma membrane translocation were increased significantly (p < 0.05 versus normoxic H0 group, n = 6) in response to repetitive hypoxic exposure (H1-H4) at an early phase of hypoxic preconditioning, but no significant changes of cPKC alpha and betaI membrane translocation were found during cPKC alpha, betaI, betaII and gamma protein expression both in hippocampus and cortex. In addition, an extensive subcellular redistribution of cPKC betaII and gamma was detected by immunohistochemistry staining in the cortex after repetitive hypoxic exposures (H3). However, a significant decrease in the expression of cPKC gamma protein (p < 0.05 versus H0 group) was found only in the cortex of delayed hypoxic preconditioned mice (H5-H6). These results suggest that the activation of cPKC betaII and gamma may be involved in the early phase of cerebral hypoxic preconditioning and the changes in cPKC gamma protein expression may participate in the development of the late phase of cerebral hypoxic preconditioning as well as selective vulnerability to hypoxia both in cortex and hippocampus.

Animals↗
PubMedDate not supplied

Modeling and simulation of the swelling behavior of pH-stimulus-responsive hydrogels.

The modulation of the swelling ability of the hydrogel matrix by pH-stimulus enables the dynamic control of the swelling forces, thereby obtaining effective diffusivity and permeability of the solutes, or mechanical energy from the hydrogel. In this work, a chemo-electro-mechanical model describing hydrogel behavior, based on multi-field effects, is developed to simulate the swelling and shrinking of these fascinating bio-materials, and it is termed the multi-effect-coupling pH-stimulus (MECpH) model. This model accounts for the ionic fluxes within both the hydrogel and solution, the coupling between the electric field, ionic fluxes, and mechanical deformations of the hydrogel. The main contribution of this model is to incorporate the relationship between the concentrations of the ionized fixed-charge groups and the diffusive hydrogen ion, which follows a Langmuir isotherm, into the Poisson-Nernst-Planck system. To validate this MECpH model, one-dimensional steady-state simulations under varying pH solution are carried out via a meshless Hermite-Cloud methodology, and the numerical results are compared with available experimental data. It is shown that the presently developed MECpH model is accurate, efficient, and numerically stable.

Chlorides↗
PubMedDate not supplied

CoMFA, CoMSIA, and molecular hologram QSAR studies of novel neuronal nAChRs ligands-open ring analogues of 3-pyridyl ether.

3-Pyridyl ethers are excellent nAChRs ligands, which show high subtype selectivity and binding affinity to alpha4beta2 nAChR. Although the quantitative structure-activity relationship (QSAR) of nAChRs ligands has been widely investigated using various classes of compounds, the open ring analogues of 3-pyridyl ethers have been less involved in these studies due to the greater flexibility of this kind of molecule. In this study, two three-dimensional QSAR techniques and one two-dimensional QSAR technique were used to correlate the molecular structure with the biological activity of 64 analogues of 3-pyridyl ethers. Three different QSAR models were established. Their performances in the QSAR studies of open ring analogues of 3-pyridyl ethers were evaluated by the statistical values in the corresponding models. All models exhibited satisfactory predictive power. Of these models, the HQSAR behaved optimally in terms of the statistical values with q2=0.845, r2=0.897. Finally, graphic interpretation of three different models provided coincident information about the interaction of the ligand-receptor complex and supplied useful guidelines for the synthesis of novel, potent ligands.

Ethers↗
PubMedDate not supplied

Analysis of nubbin expression patterns in insects.

Previous studies have shown that the gene nubbin (nub) exhibits large differences in expression patterns between major groups of arthropods. This led us to hypothesize that nub may have evolved roles that are unique to particular arthropod lineages. However, in insects, nub has been studied only in Drosophila. To further explore its role in insects in general, we analyzed nub expression patterns in three hemimetabolous insect groups: zygentomans (Thermobia domestica, firebrat), dyctiopterans (Periplaneta americana, cockroach), and hemipterans (Oncopeltus fasciatus, milkweed bug). We discovered three major findings. First, observed nub patterns in the ventral central nervous system ectoderm represent a synapomorphy (shared derived feature) that is not present in other arthropods. Furthermore, each of the analyzed insects exhibits a species-specific nub expression in the central nervous system. Second, recruitment of nub for a role in leg segmentation occurred early during insect evolution. Subsequently, in some insect lineages (cockroaches and flies), this original role was expanded to include joints between all the leg segments. Third, the nub expression in the head region shows a coordinated change in association with particular mouthpart morphology. This suggests that nub has also gained an important role in the morphological diversification of insect mouthparts. Overall, the obtained data reveal an extraordinary dynamic and diverse pattern of nub evolution that has not been observed previously for other developmental genes.

Amino Acid Sequence↗