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Biomedical subjects

R Yang

Publications and source records attributed to R Yang.

At least 127 records · Page 7Linked to original sources
PubMed1999

Hypertension and endothelial dysfunction in apolipoprotein E knockout mice.

Mice lacking ApoE (Apoe(-/-)) develop initially hypercholesterolemia and lastly atherosclerosis. This study examined hemodynamics and endothelial function in 6-week-old Apoe(-/-) mice with hypercholesterolemia only, 7.5-months-old Apoe(-/-) mice with both hypercholesterolemia and atherosclerosis, and age matched controls. One day after implantation of catheters into the carotid artery, arterial pressure was measured in conscious, unrestrained mice. Compared with the respective controls, there was a significant increase in arterial pressure and the ratio of left ventricular weight to body weight in 7.5-month-old Apoe(-/-) mice but not in 6-week-old Apoe(-/-) mice. Histopathological analysis demonstrated significant renal artery disease in the form of extensive atheromatous plaques only in 7.5-month-old Apoe(-/-) mice, whereas no atherosclerotic lesions were found in 6-week-old Apoe(-/-) mice. For evaluation of endothelial function, a laser Doppler perfusion imager with a computer-controlled optical scanner was used to measure cutaneous blood perfusion on the dorsal side of one hind paw before and after topical application of mustard oil, which is known to induce nitric oxide-mediated vasodilation. The mustard oil treatment elicited a substantial increase in blood perfusion (P<0.01), which was similar between 6-week-old Apoe(-/-) mice and controls but significantly blunted in 7.5-month-old Apoe(-/-) mice versus control mice, suggesting nitric oxide-mediated vasodilation is diminished in 7.5-month-old Apoe(-/-) mice but not in 6-week-old Apoe(-/-) mice. In contrast, the increase in blood perfusion induced by topical administration of cilostazol, which induces vasodilation via cyclic adenosine monophosphate, was not different between 7.5-month-old Apoe(-/-) mice and controls. Thus hypertension and endothelial dysfunction observed in 7.5-month-old Apoe(-/-) mice may be due mainly to atherosclerosis.

Age Factors↗
PubMed1999

Anticonvulsion effect of acupuncture might be related to the decrease of neuronal and inducible nitric oxide synthases.

To measure the levels of hippocampal nitric oxide synthase isoforms in penicillin induced epilepsy and to test the effect of electroacupuncture (EA) on changes of these levels during epilepsy, we injected penicillin into rat hippocampus to make an epilepsy model and performed electroacupuncture treatment on "Feng Fu" (DU 16) and "Jin Suo" (DU 8) points in Wistar rats. Nitric oxide synthase (NOS) mRNA levels of rat hippocampus were determined by reverse transcription-polymerase chain reaction (RT-PCR). The neuronal nitric oxide synthase (nNOS) mRNA markedly increased (p<0.01) and inducible nitric oxide synthase (iNOS) mRNA significantly emerged during epilepsy, whereas no significant change in epithelial nitric oxide synthase (eNOS) mRNA was observed. EA inhibited the epilepsy and decreased nNOS (p<0.01) and iNOS (p<0.01) correspondingly but had no effect on the amount of eNOS mRNA. The data suggest that penicillin-induced epilepsy caused an increase in nNOS and iNOS, and the EA anticonvulsant effect might be related to the decrease of these nitric oxide synthases.

Animals↗
PubMed1999

Contact lens-induced infection--a new model of Candida albicans keratitis.

PURPOSE: A model of experimental keratomycosis was established that mimics human disease in which the only fungi present are those that are actively growing within the cornea. METHODS: Dutch-belted rabbits received a subconjunctival injection of triamcinolone acetonide to one eye. One day later the epithelium was removed from the central cornea and a standardized inoculum of Candida albicans blastoconidia was placed on the corneal surface and covered with a contact lens. The lids were closed with a lateral tarsorrhaphy. After 24 hours, the lid sutures and contact lens were removed. Five days later the animals were killed, and their corneas were subjected to separate isolate recovery and histology studies. A group of similarly infected rabbits without corticosteroid injection served as controls. RESULTS: Both groups developed invasive corneal disease. Although isolate recovery was not significantly different from corticosteroid-treated rabbits compared with controls, fungal biomass was increased. Hyphal invasion was limited to the anterior cornea in control eyes, but penetrated deep stroma in most of the corticosteroid-treated rabbits. CONCLUSIONS: Invasive corneal disease can be established with a surface inoculum. Corticosteroid administration increased corneal penetration of hyphae. Quantitative isolate recovery is not a reliable measure of the fungal load within the cornea.

Animals↗
PubMed1999

[Effect of electroacupuncture and 7-NI on penicillin-induced epilepsy and their relation with intrahippocampal NO changes].

In order to investigate the effect of 7-nitroindazole (7-NI) on penicillin-induced epilepsy and the relationship between NO and anti-epileptic effect of electro-acupuncture, computerized physiological polygraph and NO-sensitive electrode with potentiostat were respectively used to record the total power spectrum (TPS) of EEG and the concentration of NO in rat hippocampus pretreated with electro-acupuncture or 7-NI for 30 min before penicillin. The results showed that the TPS of EEG and concentration of NO in hippocampus increased greatly after the epilepsy induction. Treatment with electroacupuncture inhibited the TPS of EEG sharply (P < 0.01). The latency and threshold of epilepsy induction were decreased by 7-NI, but paroxysm abated and the TPS was inhibited (P < 0.05) as compared with the control group. Both pretreatments with 7-NI and electroacupuncture decreased the NO concentration (P < 0.01). The above results suggest that the propagation of penicillin-induced seizures is facilitated by nNOS, but with some increase in the latency and threshold of induction. Electroacupunture may inhibit seizure through decreasing nNOS transcription in hippocampus.

Animals↗
PubMed1999

[Lipid peroxide damage in retinal ganglion cells induced by microwave].

The determination of lipid peroxide damage in the primary cultured pig retinal ganglion cells induced by microwave can provide some experience on the effect of microwave and the protection from its damage. Retinal ganglion cells were cultured in vitro and exposed to different intensities or time of microwave, and cultured for another 48 hours. The content of superoxide dismutase (SOD) and malondialdehyde (MDA) was detected. Results showed that the content of MDA was increased and SOD decreased after radiation. After 48 hours in culture, the content of MDA recovered, and SOD increased. It is concluded that microwave induced the lipid peroxide damage in primary cultured retinal ganglion cells. These damages were recoverable in certain range of intensity or time.

Animals↗
PubMed1999

[Risk state analysis on lung cancer of male in Xuanwei, China].

The analysis of lung cancer risk factors among male population was based on the data of a retrospective cohort study conducted during 1976-1996 in Xuanwei, China. The results verified that the indoor air pollution from burning smoky coal was the main cause of high lung cancer mortality, and found that cigarette smoking was also significantly related with the lung cancer mortality. Using risk state analysis theory, fuel types(including household stove improvement), smoking and the history of chronic bronchitis were selected as the covariance for the analysis. A risk state analysis model for male lung cancer in Xuanwei was established. The model can be used to quantitatively estimate the risk of lung cancer and to determine high risk population and individuals. The model is helpful for the prevention of lung cancer in Xuanwei.

Adult↗
PubMed1999

[Sequencing and analysis of 16S rDNA sequences for P. cocovenenans subsp farinofermentans].

In order to fix the phylogenetic taxonomic position of P. cocovenenans subsp. farinofermentans and describe its relationships with other closed species, seven primers were designed to amplify and sequence the 16S rDNA of 4 strains of it by using a clonal sequencing or direct sequencing method. The 16S rDNA sequence of the 4 strains were aligned with the 16S rDNA sequences of other species in genus Burkholderia, and the polygenetic tree was produced by using a Clustal V and treeview software. The results showed that P. cocovenenans subsp. farinofermentans was in a high homology with Burkholderia gladioli and Burkholderia cocovenenans, and they formed an independent phylogenetic clustal of genus Burkholderia.

DNA, Recombinant↗
PubMed1999

[Preparation and application of a new chloromethylstyrene encapsulated silica single anion column].

The silanized silica was firstly encapsulated with chloromethylstyrene and then quaternized by N, N-dimethylbenzylamine. Thus a new kind of strong anion stationary phase was prepared. This strong anion silica column has superior separation ability for the anions by using indirect ultraviolet detection with wavelength at 254 nm and the mobile phase of V(methanol):V(0.125 mol/L NaH2PO4) = 60:40. Moreover, separation of mono- and di-petroleum sulfonates in Yumen sample could also be good with gradient elution. The sample was first eluted with 100% A [V(methanol):V(water) = 60:40] for 1 min, then the eluent was changed linearly to 100% B [V(0.125 mol/L sodium phosphate monobasic):V(methanol) = 60:40] within 1 min, then the sample was continuously eluted with 100% B for 6 min.

Chromatography, High Pressure Liquid↗
PubMed1999

[A new viscoelastic model for granulocytes].

In this paper, a new viscoelastic model for granulocytes was introduced. The stress was placed on the theory and its experimental results of three-parameter viscous model with micropipette aspirating technique. The small deformation of single rat granulocyte into the micropipette was analyzed by the model. Within the small deformation, the fit of the experiment data using the three-parameter viscous model was more satisfactory than that using the standard solid model, and the former suggested that cytoplasm of granulocyte was treated as a liquid rather than a solid.

Animals↗
PubMed1999

Diagnosis of trichinosis by indirect fluorescent antibody test with Trichinella larva section.

AIM: To evaluate the value of indirect fluorescent antibody test (IFAT) in diagnosing trichinosis. METHODS: IFAT using frozen section of the purified Trichinella larvae as antigen was employed to detect anti-Trichinella antibodies in sera from mice infected with Trichinella spiralis and the patients with trichinosis. Sera from patients with trichinosis were collected at different time intervals after onset of the disease and after treatment with albendazole. Sera from patients with other parasitic diseases and healthy individuals were used as control. RESULTS: The anti-Trichinella antibodies were detected in 15 infected mice as early as 2 weeks after infection, and in 86.5% of 467 patients with trichinosis. Sera from patients with filariasis, echinococcosis and healthy controls were all negative. 8 of 48 (16.7%) cases with paragonimiasis showed positive cross reaction. The antibody positive rate of patients with trichinosis was 70.2% one week after onset of disease and increased to 91.0%, 95.8% and 100% at two, three and four weeks after onset, respectively. The frozen section of the larvae can be stored at -20 degrees C for 5 years without loss of antigenicity. The IFAT positive rate was increased from 87.5% before treatment to 100% one week after treatment, and the serum antibody titers were elevated as well. The antibody negative conversion rate of the patients was 24% at one month after teratment and increased to 75% at four months after treatment. CONCLUSION: IFAT using frozen section of the purified Trichinella larvae as antigen is highly sensitive and specific for the diagnosis of trichinosis and evaluation of the therapeutic effect.

Animals↗
PubMed1999

[Photocurrent spectra of undoped LECSIGaAs].

Extrinsic photocurrent spectra of undoped LECSIGaAs have been measured to investigate the deep levels in this material. A broad photocurrent response band M1 ranging from 0.40 to 0.70 eV has been observed. M1 band reveals five peaks at 0.46, 0.49, 0.56, 0.65 and 0.69 eV, respectively. The onset thresholds for the 0.46, 0.49, 0.56 and 0.69 eV peaks are 0.44, 0.47, 0.51 and 0.67 eV, respectively. It is likely that M1 band is due to different deep levels and each of these deep levels has a concentration larger than 10(14) cm(-3). The origin of M1 band is discussed and possible associations of the 0.44, 0.47 and 0.51 eV thresholds with copper acceptor, EL3 and oxygen donor are presented. The relationship between M1 band and the photoresponse behavior of drain current of GaAs field effect transistor was also investigated.

English Abstract↗
PubMed1999

[Anharmonicity of local vibrational mode of carbon acceptor in GaAs and its effect on main absorption band].

A sideband on the low energy side of the local-vibrational-mode main absorption band of carbon acceptor in GaAs was observed. The difference between the peak frequency of the main absorption band and that of the sideband is 3.5 cm(-1). The integrated absorption of the sideband varies with temperature and has an effect on the temperature dependence of the main absorption band. It is likely that the sideband originates from the anharmonicity of the local vibrational mode itself.

English Abstract↗
PubMed1998

Mitochondrial respiratory mutants in yeast inhibit glycogen accumulation by blocking activation of glycogen synthase.

Control of glycogen synthase activity by protein phosphorylation is important for regulating the synthesis of glycogen. In this report, we describe a regulatory linkage between the ability of yeast cells to respire and activation of glycogen synthase. Strains containing respiration-deficient mutations in genes such as COQ3, required for the synthesis of coenzyme Q, were reduced in their ability to accumulate glycogen in response to limiting glucose. This lowered glycogen accumulation results from inactivation of the rate-determining enzyme, glycogen synthase (Gsy2p). Reduced glycogen synthase activity is coincident with lowered glucose 6-phosphate and ATP levels in the respiration-deficient cells deprived of glucose. Alanine substitutions of three previously characterized phosphorylation sites in Gsy2p, Ser-650, Ser-654, or Thr-667, each suppressed the glycogen defect in cells unable to respire, suggesting that inactivation of this enzyme is mediated by phosphorylation of these residues. Inactivation of glycogen synthase requires the RAS signaling pathway that controls cAMP-dependent protein kinase and is independent of Pho85p previously identified as a Gsy2p kinase. These results suggest that yeast cells unable to shift from a fermentative to a respiratory metabolic regimen block accumulation of glycogen by inactivating Gsy2p through protein phosphorylation.

Adenosine Triphosphate↗
PubMed1998

[Identification of a mutation hotspot in exon 8 of Wilson's disease gene by cycle sequencing].

OBJECTIVE: To screen for mutation hotspot of Wilson's disease (WD) gene in Chinese. METHODS: Cycle sequencing was used to detect mutation in exon 8 of WD gene in 30 patients with WD. RESULTS: The same missense mutation, Arg778Leu, was identified in 14 WD patients, four of which were homozygous and the others were heterozygous for this mutation. The frequency of this mutation was 30%. CONCLUSION: The codon 778(CGG-->CTG) of exon 8 in WD gene was one of mutation hotspots in Chinese.

Adolescent↗
PubMed1998

Mechanisms of growth control of Kaposi's sarcoma-associated herpes virus-associated primary effusion lymphoma cells.

Primary effusion lymphoma (PEL) is a distinct clinicopathologic entity associated with Kaposi's sarcoma-associated herpes virus (KSHV). Several cytokines, including interleukin-6 (IL-6), basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF) may be important for survival of KS cells. However, little is known about the interaction of cytokines with KSHV-infected lymphocytes from PEL. Therefore, we investigated what cytokines were produced by KSHV-infected PEL cell lines (KS-1, BC-1, BC-2), what cytokine receptors were expressed by these cells, what response these cells had to selected cytokines, and what was the effect of IL-6 antisense phosphorothioated oligonucleotides. Reverse transcriptase-polymerase chain reaction (RT-PCR) and protein studies showed that these three cell lines produced IL-10, IL-6, and the receptors for IL-6. The granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1beta, IL-8, IL-12, bFGF, PDGF, and c-kit transcripts were not detected in the cell lines. High levels (0.7 to 5 ng/mL/10(6) cells/48 hours) of IL-6 protein were consistently detected in supernatants of the cell lines by enzyme-linked immunosorbent assay (ELISA) tests. In clonogenic assays, interferon-alpha (IFN-alpha) and IFN-gamma suppressed the clonal growth of the PEL cells, but GM-CSF, IL-4, IL-6, IL-8, IL-10, and oncostatin M did not change it. We examined for several autocrine loops that have been suggested to occur in KS. Experiments using antisense oligonucleotides showed that the clonal growth of KS-1 and BC-1 was nearly 100% inhibited by IL-6 antisense oligonucleotides (10 micromol/L), but not at all by either oligonucleotides (</=10 micromol/L) to IL-6 sense, IL-6 scrambled, viral IL-6 (vIL-6) antisense, or IL-10 antisense. Furthermore, the IL-6 antisense oligonucleotides had no effect on two B-cell lymphoma cell lines, which were not infected with KSHV. Addition of IL-6 antibody did not inhibit clonal growth of any of the cell lines. Taken together, we have defined the cytokines and their receptors expressed on PEL cells and have found that these cells synthesized IL-6 and IL-6 receptors; interruption of this pathway by IL-6 antisense oligonucleotides specifically prevented the growth of these cells. These findings will offer potential new therapeutic strategies for PEL.

Cell Division↗
PubMed1998

Effects of cardiotrophin-1 on haemodynamics and cardiac function in conscious rats.

Cardiotrophin-1 (CT-1), a newly discovered cytokine, has been shown to induce cardiac hypertrophy in vitro and in vivo. The present study examined the effects of CT-1 on haemodynamics and cardiac function. The measurements of haemodynamic parameters were made using in-dwelling catheters and flow probes in conscious, unrestrained rats. Intravenous administration of CT-1 caused a dose-dependent decrease in mean arterial pressure (MAP), and an increase in heart rate (HR). CT-1 (100 micrograms/kg) significantly elevated cardiac output and HR, and decreased MAP and systemic vascular resistance. Stroke volume was unaltered, suggesting that the CT-1 induced increase in cardiac output was secondary to increased HR. There was no significant difference in left ventricular maximal dP/dt between the CT-1-treated and vehicle-treated groups, suggesting that CT-1 might not induce a meaningful change in ventricular contractility. Pretreatment with intravenous N omega-nitro-L-arginine methyl ester, a specific inhibitor of nitric oxide synthase, significantly attenuated the depressor and tachycardic responses to CT-1. These results indicate that nitric oxide plays an important role in mediating the haemodynamic effects of CT-1.

Animals↗
PubMed1998

Differential effects of bone mineral content and bone area on vertebral strength in a swine model.

Since the biomechanical competence of a vertebral body may be closely related to the content and distribution of the bone mineral, we have evaluated the effects of projected vertebral bone area (BA) and bone mineral parameters [bone mineral content (BMC) or bone mineral density (BMD)] on their biomechanical competence. We used dual-energy X-ray absorptiometry (DXA) to assess the bone mineral parameters of 36 swine thoracic vertebrae (T1-T12) and 15 lumbar vertebrae (L1-L5) after removal of the posterior elements. The failure load, compressive stress, and the stored strain energy of these vertebral bodies were assessed by a uniaxial compressive test using an MTS 810 testing system. Multiple regression analysis showed a significantly negative effect of BA and significantly positive effect of BMC on the biomechanical competence (compressive stress, r2 = 0.67, P < 0.0001; failure load, r2 = 0.75, P < 0.0001). However, the stored strain energy was only related to the BMC (r2 = 0.35, P < 0.0001). The contributory effects of BMC and BA on the biomechanical competence were not equal. The effects of BMC was larger than BA in determining the failure load and stored strain energy, whereas the reverse was found for the compressive stress. Using the log-transformed parameters as the regressors resulted in similar results. These results suggested the differential effects of BA and BMC in determining the biomechanical competence of vertebral bodies. We recommend the use of both parameters instead of BMD alone for evaluation of the vertebral biomechanical competence.

Absorptiometry, Photon↗