Biomedical subjects

Y Huang

Publications and source records attributed to Y Huang.

At least 397 records · Page 22Linked to original sources

PubMed2000

[Molecular design and immunoreactivity studies of multiple antigen peptide corresponding to hypervariable region 1 sequence of hepatitis C virus].

OBJECTIVE: To get more new information about the antigen epitopes of the hypervariable region 1 (HVR1) within the putative envelope glycoprotein of hepatitis C virus (HCV). METHODS: We designed and synthesized linear epitope peptides (LP) and multiple antigen peptide (MAP, symmetric 8 branches) derived from 22 amino acids (position 390-411aa) of HCV-BJ (HCV 1b genotype) HVR1. We compared the binding-reactivity of LP with MAP to native anti-HVR1 antibody in HCV-infected patients sera. In addition, the HCV genotype was tested to assess the prevalence of anti-HVR1 by cleaving PCR products with restriction enzyme. RESULTS: (1)There was a significant difference (P< 0.0001) of mean A450 between anti-MAP (mean +/- s =0.461 +/- 0.590) and anti-LP (mean +/- s =0.145 +/- 0.166), and the immunoreactivity of MAP and LP to the native antibody had a significant association (P < 0.001). (2)The rate of anti-LP and anti-MAP detection in 59 anti-HCV2.0 positive sera was 29% and 58% respectively. (3)The binding of MAP to antibody protein in sera from patients infected with other genotypes besides HCV 1b genotype was observed. CONCLUSION: The binding-reactivity of MAP to native antibody was obviously higher than that of LP, and there is a cross-reaction between them. It was possible to analyse conformational antigen epitopes in the region and develop HCV molecular vaccine by synthesizing MAP corresponding to HCV HVR1 sequences.

Hepatitis C Antigens↗

PubMed2000

[Modification of surface of Dacron materials by UV irradiation for prevention of microbial adhesion].

UV irradiation grafting method was used to modify the surface of Prosthetic Valve materials (Dacron) for prevention of bacteria-adhesion, and PEG was introduced to the surface of Dacron by this method. The result showed that the chemical magnifying effect of PEG improved the grafting of heparin on the material surface. This method can obviously reduce the number of adherent bacteria.

Bacterial Adhesion↗

PubMed2000

[The development of an extracting method for high frequency components of abnormal intra-QRS of exercise ECG signal].

This article introduces a method of extracting high frequency components of abnormal intra-QRS of exercise ECG signal by using spline function interpolation algorithm, and defines QRSe of the residual signal as quantitative index. Some expected results have been obtained. This method is an effective measuring approach to further researches on the high frequency components of exercise and other ECG signals.

Electrocardiography↗

PubMed2000

Cryptorchidism induces mouse testicular germ cell apoptosis and changes in bcl-2 and bax protein expression.

Up to half of the germ cells die during their development. The mechanism involved in their death is still unclear. We investigated the possibility that the testicular germ cell loss may be due to a change in the testicular temperature and apoptosis through the interplay of bcl-2 and bax proteins. To investigate the effect of temperature on apoptosis and the role of bcl-2 and bax proteins in apoptosis in adult mouse testis, we used the experimental unilateral cryptorchidism model. We found that the weight of the affected testis decreases in 6 to 15 days after operation (p < 0.05). H&E staining showed vacuolization of the seminiferous epithelium and the appearance of multinucleated giant cells with loss of germ cells. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling method (TUNEL) showed positive staining germ cells scattered in normal testicles that increased significantly 6 to 15 days after experimental cryptorchidism (p < 0.05). Positive cells were mainly primary spermatocytes and round spermatids. DNA ladder was seen in 1.5% agarose gel electrophoresis in 6 to 15 days-operated testicles. Biotin-avidin DCS system indirect immunofluorescence technique indicated that the bcl-2 protein was chiefly distributed in the cytoplasm of germ cells in normal testicles, whereas the bax protein was chiefly expressed in the cytoplasm of germ cells in 6 to 15 days-operated testicles. Western blot analysis showed that the bcl-2 protein down-regulated and the bax protein up-regulated apoptosis. Our data indicated that cryptorchidism-induced testicular cell degeneration was mediated by apoptosis probably as the result of increased temperature in the testicle; bcl-2 and bax proteins played important roles in male germ cell apoptosis.

Animals↗

PubMed2000

Respiratory symptoms and use of medical care associated with child day care and health care plan among preschool children.

This study compared the risk of respiratory infections in pre-school children (under 6-year-old) attending day care center and those taken care of at home by controlling for the type of health plan and sociodemographic characteristics. The study population consists of members of two health plans residing in two South Carolina counties. Results show that the risks of respiratory symptoms were higher among children attending day care settings than those taken care of at homes although this relationship is more apparent among Medicaid children than among HMO children. While the type of child care has weak influence on medical care utilization, the type of health plan exerts strong influence on utilization for both day care and home care groups.

Chi-Square Distribution↗

PubMed2000

[A study of transgenic IFV cattle integrated with human serum albumin gene].

The mammary gland expression vector (pcDNA 3.1-GCALBm) containing the full-length sequence of human serum albumin (hALB) cDNA and intron 1 as well as the goat beta-casien gene promoter and 5' up-stream regulatory sequence was constructed. The vector was micro-injected into bovine IVF eggs. The embryos were in vitro cultured to the late stage of morulae, and then few embryo cells were aspirated for the implantation detection of target gene integration and SRY DNA sequence using nested-PCR. Afterwards, ten integrated embryos were selected to transfer into eight recipients and three were pregnant. The pregnant rate was 37.5%(3/8). However, two were miscarried in mid-trimester but one was pregnant at term to deliver a male transgenic cattle integrated with hALB mini-gene. The transgenic efficiency was 12.5% (1/8).

Animals↗

PubMed2000

Dietary conjugated linoleic acid mixture affects the activity of intestinal acyl coenzyme A: cholesterol acyltransferase in hamsters.

The present study was designed to study the mechanisms by which dietary conjugated linoleic acids (CLA) decrease serum cholesterol. Hamsters were fed a semi-synthetic diet containing 1 g cholesterol/kg diet with or without supplementation with 20 g linoleic acid (LA) and 20 g CLA/kg diet. After 8 weeks, serum fasting total cholesterol (TC) and triacylglycerol (TG) were significantly lower in the LA-supplemented and CLA-supplemented groups compared with those of the control (CTL) hamsters. In contrast to LA, CLA significantly lowered hepatic cholesterol but it increased the level of adipose tissue cholesterol, suggesting that the hypocholesterolaemic mechanism of CLA is different from that of LA. CLA decreased the activity of intestinal acyl CoA:cholesterol acyltransferase (ACAT) whereas LA had no effect on this enzyme. Consequently, CLA supplementation increased the faecal excretion of total neutral sterols, but it had no or little effect on the faecal acidic sterols. If the ACAT is associated with cholesterol absorption, the part of mechanisms by which CLA decreases serum cholesterol may involve down-regulation of intestinal ACAT activity.

Acyl Coenzyme A↗

PubMed2000

[Bridging artery defect with autogenous vein under required anastomosing tension--a theoretical analysis based on related biomechanical evidence].

This study was aimed to establish a rabbit model of bridging artery defect with autogenous vein under required tension by selecting and appropriate length of graft. The uniaxial loading test in longitudinal direction was performed using 14 femoral arteries and 14 femoral veins. The tension(F)-strain(lambda) curve was measured and the exponential form F = m1 * [em2(lambda-1)-1] was employed to fit the curve. The results showed that with the range of 35.0 mm actual isolated length (AIL), the exponential form Fa = 0.22[e5.75(lambda a-1)-1] and Fv = 6.15 * 10(-3) [e7.89(lambda v-1)-1] could well fit the experimental data of rabbit's femoral artery and vein respectively. Therefore to make sure the required anastomosing tension F, the length of vein graft(LVG) should qualify the equation: (LVG/1.64) x lambda v + [(AIL - ADL)/1.58] x lambda a = AIL while 1.65 and 1.58 are the physiological stretch ratio of artery and vein, lambda v and lambda a stand for that of vein and artery under tension F, respectively.

Anastomosis, Surgical↗

PubMed2000

Mechanism of free radicals on the molecular fluidity and chemical structure of the red cell membrane damage.

This paper investigated the mechanism for the rheological dysfunction of red blood cell (RBC) caused by free radicals. Normal RBCs were collected from healthy volunteers. Fenton system was added to the RBCs and allowed to react for 30 minutes in vitro. The RBC membrane molecules were damaged due to the free radicals reaction. It was found that: (1) The protein configurations changed such as the ratio decreasing in alpha-helix and increasing in both of beta-sheet and coiled-coil; (2) -P=O/-P-O chemical group ratio in phospholipids increases; (3) the molecular rotational correlation times of proteins and lipids were extremely elevated; (4) the membrane shear elastic modulus was significantly enhanced. The present results support that the chemical structure changes led by free radicals are ultimately responsible for the reduction in molecular fluidity of RBC membrane.

Elasticity↗

PubMed2000

Different mechanisms mediate beta adrenoceptor stimulated vasorelaxation of coronary and femoral arteries.

AIM: To determine whether different mechanisms mediate vasorelaxation of swine coronary and femoral arteries induced by beta adrenoceptor stimulation. METHODS: The organ-bath was used to observe the tension changes in rings of coronary and femoral arteries to different concentrations of isoprenaline (ISO) after endothelium removal, nitric-oxide synthase (NOS) inhibition by L-NMMA and beta 1 and/or beta 2 adrenoceptor antagonization. RESULTS: Endothelium removal, NOS inhibition, beta 2 adrenoceptor antagonization did not change the vasorelaxation induced by ISO in coronary artery, however, abolished the vasorelaxation in femoral artery. beta 1 Adrenoceptor antagonization did not change the tension of femoral artery, but abolished the ISO induced vasorelaxation of coronary artery. CONCLUSIONS: Vasorelaxing effect of ISO in swine coronary artery is mediated through beta 1 adrenoceptor and not through L-arginine/nitric oxide pathway, however, in femoral artery, it is mediated through beta 2 adrenoceptor and L-arginine/nitric oxide pathway.

Adrenergic beta-Antagonists↗

PubMed2000

Inhibitory effects of purified green tea epicatechins on contraction and proliferation of arterial smooth muscle cells.

AIM: The present study was aimed to examine the vasorelaxant and antiproliferative responses to purified green tea epicatechin mixture, (-)epicatechin and (-)epigallocatechin gallate on rat arterial smooth muscle cells. METHODS: Changes in isometric force were measured by Grass force transducer and effects on cell proliferation were evaluated using [3H]thymidine incorporation assay. RESULTS: Epicatechin mixture, (-)epicatechin and (-)epigallocatechin gallate, which we isolated and purified from jasmine green tea, concentration-dependently, reduced the contractile response to phenylephrine in rat isolated aortic rings with (-)epigallocatechin gallate being more effective. These three agents also inhibited [3H]thymidine incorporation into DNA in cultured rat aortic smooth muscle cells in a concentration-dependent manner. CONCLUSION: The purified epicatechin derivatives from jasmine green tea relaxed the isolated rat arteries preconstricted by phenylephrine and inhibited aortic smooth muscle cell proliferation.

Animals↗

PubMed2000

[Molecular design and immunogenicity studies of multiple antigenic peptide corresponding to envelope glycoprotein hypervariable region 1 of hepatitis C virus].

OBJECTIVE: To study the immunogenicity of multiple antigen peptide (MAP) corresponding to the hypervariable region 1 (HVR1) within the putative envelope glycoprotein E2/NS1 of hepatitis C virus (HCV). METHODS: Basing upon the E2/NS1 consensus sequence of HCV-BJ (isolate of Beijing) which we had obtained previously, and referring to several HCV HVR1 sequences reported by foreign authors, we synthesized a linear epitope peptide (LP) and a MAP (symmetric 8 branches) according to 22 amino acids (position 390 - 411 aa) of HCV-BJ HVR1 on the basis of our prediction to their antigenicity parameters. Then, the Balb/C mice and rabbits were immunized with IP or MAP respectively. We compared the immunogenicity of MAP with Lp. RESULTS: The results showed that the immunogenicity of MAP which elicited high-titer antibody more than 1:40 960 was much stronger than that of LP (1:1 280). CONCLUSIONS: It suggests that the immunogenicity of peptide corresponding to HCV HVR1 was stronger by using MAP conformation, and this provide a basis for designing HCV molecular vaccine using MAP.

Animals↗

PubMed2000

Role of endothelium/nitric oxide in vascular response to flavonoids and epicatechin.

AIM: To examine the role of endothelium in the vascular responses to flavonoids, baicalein, baicalin, cardamonin, alpinetin, and to purified jasmine green tea (-)epicatechin in the isolated rate mesenteric artery rings. METHODS: The isometric contraction was measured by Grass force-displacement transducers. RESULTS: Both baicalein and baicalin enhanced the phenylephrine-induced contractile response in the endothelium-intact rings. This enhancement was abolished by pretreatment with the nitric oxide inhibitor NG-nitro-L-arginine or in the absence of the endothelium. Both flavonoids also inhibited the acetylcholine-induced endothelial nitric oxide-dependent relaxation. In contrast, cardamonin, alpinetin or (-)epicatechin induced both endothelium-dependent and -independent relaxation. NG-nitro-L-arginine meyhyl ester or endothelium denudation attenuated the endothelium-dependent relaxation to the same extent. CONCLUSION: Baicalein and baicalin enhanced the phenylephrine-induced contraction most likely through inhibiting production or/and release of endothelial nitric oxide. Whilst, cardamonin-, alpinetin- or (-)epicatechin-induced endothelium-dependent relaxation is primarily mediated through endothelial nitric oxide.

Animals↗

PubMed2000

[Textual research on history of glasses].

Early glasses is nothing but a single piece of glass without a frame. The latter originating from the "Reading stone" was a long one. It was both aided and retarded by social condition style, quality of available materials and technology. It is reasonable to make a few conclusions about the invention along the line suggested by Rosen; most likely, the inventor was a lay person of Pisa who wished to keep the manufacturing processes a secret in order to make a profit, the date of the invention is most likely around 1270 - 1280. The inventor was by two missionaries of St. Catherine's Friar dirdano da Rivolta and Alessando Spina. Lastly, the author advocates the use of CR-39, based on the following reasons: a high resin plastic, fragile resistance, high refractive index, light weight, and resistance to fogging.

Eyeglasses↗

PubMed2000

[Distribution pattern and its dynamics of Taxus chinensis var. mairei population on Yunbaoshan Mountain].

Field data were sampled by the method of contiguous grid quadrate, and t-test of v/m ratio, negative binomial parameter, Green's index, Cassie's index, dispersion index, clumping index, mean crowding index and patchiness index were used to analyse the distribution pattern and its dynamics of Taxus chinensis var. mairei population. The result shows that the distribution pattern was clustering. From sapling to grown-up tree, the clustering degree was decreasing, while the big trees had a random distribution.

China↗

PubMed2000

[Effect of rhizospheric environment of VA-mycorrhizal plants on forms of Cu, Zn, Pb and Cd in polluted soil].

Maize (Zea mays L.) was inoculated with or without VA mycorrhizal (Glomus mosseae) and cultivated in a heavy metals contaminated soil. The distribution and dynamics of Cu, Zn, Pb and Cd forms in rhizosphere of maize inoculated with or without VA-mycorrhizal were analyzed with the technique of sequential extraction. Comparing with control soil, exchangeable Cu in rhizospheric soil increased significantly, and the exchangeable Cd trended down. In rhizosphere of VA-mycorrhizal maize, the amounts of Cu, Zn and Pb bound to organic matter were significantly higher than those in rhizosphere of non-mycorrhizal maize, while the four tested metals bound to carbonates and to iron and manganese oxides were constant in rhizosphere of mycorrhizal and non-mycorrhizal maize. These results illustrated that the plant roots could influence the distribution and dynamics of metal forms in rhizosphere, and much for mycorrhizal plants than for non-mycorrhizal plants. At excessive concentration of soil metals, mycorrhizal roots might decrease the bio-availability of toxic heavy metals by changing their forms. The factors that caused the change of metal fractions in rhizosphere of mycorrhizal and non-mycorrhizal plants were also discussed.

Cadmium↗

PubMed2000

Effects of resveratrol on oxidative modification of human low density lipoprotein.

OBJECTIVE: To determine the antioxidative effects of resveratrol (RES), a polyphenolic compound in red wine, on the oxidation of human low density lipoprotein (LDL) using two different oxidation systems. METHODS: Oxidation of LDL was induced by adding either Cu2+ or an azo compound. The extent of LDL modification was assessed by measuring the formation of thiobarbituric acid reactive substances (TBARS), the relative electrophoretic mobilities (REM), and the amount of oxidized LDL degradation by macrophages. RESULTS: During Cu(2+)-induced oxidation, RES reduced TBARS formation in LDL by 70.5%, REM of LDL by 42.3% and the amount of macrophage degradation by 65.7%, respectively. The lag phase of LDL oxidation was also delayed by adding RES both in the copper ion and azo compound-induced oxidation systems. CONCLUSION: RES can protect LDL against both Cu(2+)-induced and azo compound-initiated oxidative modification in vitro, which might be due to its free radical scavenging capacity.

Animals↗

PubMed2000

[Automatic modulation of refractoriness of His-Purkinje system during atrioventricular nodal reentrant tachycardia].

OBJECTIVE: To illustrate the automatic modulation of refractoriness of His-Purkinje system during atrioventricular nodal reentrant tachycardia (AVNRT) and to discuss the possible mechanisms. METHODS: Programmed electrical stimulations were performed in high right atrium (HRA) in 8 patients with AVNRT before ablation to induce tachycardia and electrocardiagraphic recordings were done synchronically when AVNRT appeared. RESULTS: All the patients had 2:1 atrioventricular (A-V) conduction when AVNRT began, 2 of whom were blocked below His bundle, 5 above His bundle and 1 unclear. After a duration of 14.03 +/- 10.03 s of 2:1 A-V conduction, 1:1 A-V conduction with bundle banch block appeared, 3 of which were right bundle branch block (RBBB), 3 left bundle branch block (LBBB), and 2 with both. Bundle branch block disappeared after a duration of 6.87 +/- 11.26 s. CONCLUSION: Effective refractory period (ERP) of His-Purkinje system at the beginning of AVNRT was modulated automatically within less than 30-60 s and thus facilitated nodal-ventricular conduction. The mechanism of this is electrical remodeling.

Adult↗