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Biomedical subjects

Y Yao

Publications and source records attributed to Y Yao.

At least 73 records · Page 4Linked to original sources
PubMed2001

[Use X-ray or CR to evaluate the operation result of the cochlear implant].

OBJECTIVE: To evaluate the cochlear implant operation by the use of X-ray or CR. METHOD: There are 15 ears 15 cases which were completed the cochlear implant operation, after operation the implant electrode array was shown by the use of X-ray or CR. RESULT: The shape and station of those were normal, average insered depth was 23.05 mm, come up to provide standard. CONCLUSION: It was an economic, convenient, objective and worthy method to evaluate the cochlear implant.

Adolescent↗
PubMed2001

[The relationships of the serum concentrations of insulin-like growth factors in fetal rats with intrauterine growth retardation].

OBJECTIVE: To observe the alterations of serum insulin-like growth factor-I,-II (IGF-I, IGF-II) in rat fetus and to investigate the relationship of serum IGFs with intrauterine growth retardation (IUGR). METHODS: 21 pregnant SD rats were randomly divided into control group (n = 9) and experimental group (IUGR group, n = 12). On day 14 of gestation, the bilateral uterine arteries and veins of experimental group were clamped for 20 minutes to build the rat IUGR models and sham surgeries were performed on control group. Fetal serum concentrations of IGFs, birth weight, the length and weight of fetal liver, lung, brain and placenta of all rats in the two groups were measured and compared. RESULTS: The serum concentrations of IGF-I,-II of IUGR group were 117.92 +/- 26.58 ng/ml and 223.19 +/- 33.35 ng/ml, respectively, which were significantly lower than those of control group (234.43 +/- 70.65 ng/ml and 397.74 +/- 23.69 ng/ml, respectively, P < 0.01). Likewise, birth weight, the length and weight of liver, lung, brain and placenta in IUGR group were significantly lower than those in control group (P < 0.05). CONCLUSION: The decrease of fetal serum concentrations of IGF-I,-II may be one of the internal factors contributing to fetal IUGR, and IGFs may play an important role in fetal growth.

Animals↗
PubMed2001

Gut barrier function damage following multiple firearm injuries in a porcine model.

OBJECTIVE: To study the characteristics and pathogenesis of gut barrier damage following multiple firearm injuries in a porcine model. METHODS: Twenty-four small pigs were divided into 4 groups: control group (n = 6, group C), group H (n = 6, gunshot-induced tangential fracture of parietal bone), group L (n = 6, gunshot-induced comminuted fracture of bilateral femora) and group M (n = 6, combined group H + L). Gastric intramucosal pH (pHi), plasma endotoxin levels in portal vein, and plasma D-lactate levels were measured and blood samples were cultured at different intervals after trauma. The animals were sacrificed at 72 h following trauma and intestinal tissues were harvested for pathological examination and diamine oxidase (DAO) activity measurement. RESULTS: In group M at 72 h, pHi was significantly lower than that of group H and L ( P < 0.01), and plasma endotoxin level was significantly higher than that of group H (P < 0.01) and group L (P < 0.05). Simultaneously, in group M, D-lactate level was markedly higher than that of group H ( P < 0.01), and incidence of positive blood culture was much higher than that of group H and L ( P < 0.05). Necrosis and exfoliation were revealed at ileum villus top in all trauma groups, especially in group M, in which ileum DAO activity declined most significantly as well. CONCLUSION: Multiple trauma is prone to cause gastrointestinal ischemia even without hemorrhagic shock. The damage of gut barrier in multiple trauma appears to be more severe than that in one-site trauma, thereby promoting gut-derived endotoxemia and bacterial translocation and contributing to the development of endogenous infection.

Amine Oxidase (Copper-Containing)↗
PubMed2001

[Cloning of the genes associated with the pathogenesis of pregnancy induced hypertension using subtractive hybridization].

OBJECTIVE: To clone the genes related to pregnancy induced hypertension (PIH) for the study of PIH pathogenesis. METHODS: The differential expressed cDNA of PIH and normal pregnant placenta were cloned using modified polymerase chain reaction based subtractive hybridization. The differential cDNA were sequenced. RESULTS: Among 86 clones from subtractive hybridization, 14 clones containing differential expressed gene fragments in PIH and normal placenta were identified, and these might be the genes associated with PIH. Compared with the expressed sequence tags (EST) in dbEST of National Center for Biotechnology Information, it showed that 11 of them were known gene fragments, and three were unknown. The three unknown gene fragments were registered in GenBank, the accession number is AF 232216, AF 232217, AF 233648 respectively. CONCLUSIONS: Fourteen PIH related genes were cloned with subtractive hybridization. A new approach to study on the pathogenesis of PIH is presented.

Cloning, Molecular↗
PubMed2000

Heterogeneity of HLA and EBER expression in Epstein-Barr virus-associated nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is an aggressive tumour of multifactorial aetiology that, although rare in most parts of the world, poses a significant mortality problem in its high incidence area of Southern China. Improved therapies are an urgent requirement and, towards this end, immunotherapeutic methods are being developed in several centres. Such strategies are dependent on the immune competence of the target tumour, in particular its expression of HLA class-I. We examined HLA class-I and -II expression in 27 primary NPC biopsies and found that 15% were extensively down-regulated for class-I expression with the majority of tumour cells appearing negative. Whilst HLA class-II was expressed at high levels in the majority of tumours, 37% showed substantial down-regulation. NPC is associated with Epstein-Barr virus (EBV). Expression of the virus-encoded EBER RNAs is accepted as a marker of EBV latency and is regarded as a valuable diagnostic criterion. EBER RNAs were expressed in all samples, but in some the level was remarkably heterogeneous, being barely detectable in many tumour cells. Our study reinforces the concept of extensive phenotypic variation in NPC. There are morphological differences between tumour cells. Some tumours express HLA class-I and/or -II, whilst others are down-regulated or negative. Individual tumours may or may not express the EBV-encoded LMP-1 protein, and individual tumour cells may express high levels of EBER, yet adjacent tumour cells express very little or none.

Adult↗
PubMed2000

Structural basis for the activation of 20S proteasomes by 11S regulators.

Most of the non-lysosomal proteolysis that occurs in eukaryotic cells is performed by a nonspecific and abundant barrel-shaped complex called the 20S proteasome. Substrates access the active sites, which are sequestered in an internal chamber, by traversing a narrow opening (alpha-annulus) that is blocked in the unliganded 20S proteasome by amino-terminal sequences of alpha-subunits. Peptide products probably exit the 20S proteasome through the same opening. 11S regulators (also called PA26 (ref. 4), PA28 (ref. 5) and REG) are heptamers that stimulate 20S proteasome peptidase activity in vitro and may facilitate product release in vivo. Here we report the co-crystal structure of yeast 20S proteasome with the 11S regulator from Trypanosoma brucei (PA26). PA26 carboxy-terminal tails provide binding affinity by inserting into pockets on the 20S proteasome, and PA26 activation loops induce conformational changes in alpha-subunits that open the gate separating the proteasome interior from the intracellular environment. The reduction in processivity expected for an open conformation of the exit gate may explain the role of 11S regulators in the production of ligands for major histocompatibility complex class I molecules.

Amino Acid Sequence↗
PubMed2000

Cloning and characterization of DIP1, a novel protein that is related to the Id family of proteins.

Using human cyclin D1 as the "bait" in a yeast two-hybrid system, together with a HL60 cDNA library, we identified a novel human nuclear protein designated DIP1. This protein is expressed in a variety of cell types, and in fibroblasts its level remains constant throughout the cell cycle. However, the level of this protein increases severalfold during the differentiation of HL60 cells. The DIP1 protein can be phosphorylated in vitro by a cellular kinase and this activity reaches its maximum in extracts obtained from cells in the G1 phase of the cell cycle. DIP1 contains a helix-loop-helix motif but lacks an adjacent basic DNA-binding domain, thus resembling the Id family of proteins. The dip1 gene is located on human chromosome 16p11.2-12, a locus that is amplified in several types of human cancer. These results suggest that DIP1 may be involved in the control of gene expression and differentiation, but its precise function remains to be determined.

Amino Acid Sequence↗
PubMed2000

p300 and p300/cAMP-responsive element-binding protein associated factor interact with human T-cell lymphotropic virus type-1 Tax in a multi-histone acetyltransferase/activator-enhancer complex.

The human T-cell lymphotropic virus, type (HTLV)-1 trans-activator, Tax, coordinates with cAMP-responsive element-binding protein (CREB) and the transcriptional co-activators p300/CBP on three 21-base pair repeat elements in the proviral long terminal repeat (LTR) to promote viral mRNA transcription. Recruitment of p300/CBP to the activator-enhancer complex, however, is insufficient to support Tax-dependent LTR trans-activation. Here, we report that the p300/CBP-associated factor (P/CAF) is a critical and integral component of the functional HTLV-1 activator-enhancer complex. The HTLV-1 Tax protein directly binds P/CAF in vitro and co-immunoprecipitates with this co-activator in vivo. The Tax mutants (K88A and V89A) defective for p300/CBP-binding and LTR trans-activation, retained their abilities to interact with P/CAF. The M47 mutant (L319R, L320S) protein, which has previously been shown to interact with p300/CBP, by contrast, failed to form complexes with P/CAF and is impaired in LTR trans-activation. Furthermore, LTR trans-activation by Tax is competitively inhibited by the adenoviral E1A 12S gene product, which displaces P/CAF from p300/CBP and inhibits the histone acetyltransferase activities of both P/CAF and p300/CBP. This inhibition is partially reversed by exogenously added P/CAF. These results imply that simultaneous recruitment of two distinct co-activators (p300/CBP and P/CAF) by Tax is essential for the assembly of a trans-activation competent, nucleoprotein complex.

Acetyltransferases↗
PubMed2000

2,3,4,5-Tetrakis[(2-hydroxyethyl)thio]tetrathiafulvalene tetrafluoroborate.

The title complex, C(14)H(20)O(4)S(8)(+)(.)BF(4)(-), is a charge-transfer complex with typical charges for the donor and anion of +1 and -1, respectively. Two centrosymmetrically related donors form a face-to-face pi-dimer with a strong intermolecular S.S interaction. These pi-dimers stack along the a axis to form a donor column. The structure is extensively hydrogen bonded.

Journal Article↗
PubMed2000

Three-layered atmospheric structure in accretion disks around stellar-mass black holes

Modeling of the x-ray spectra of the Galactic superluminal jet sources GRS 1915+105 and GRO J1655-40 reveals a three-layered atmospheric structure in the inner region of their accretion disks. Above the cold and optically thick disk with a temperature of 0.2 to 0.5 kiloelectron volts, there is a warm layer with a temperature of 1.0 to 1.5 kiloelectron volts and an optical depth around 10. Sometimes there is also a much hotter, optically thin corona above the warm layer, with a temperature of 100 kiloelectron volts or higher and an optical depth around unity. The structural similarity between the accretion disks and the solar atmosphere suggests that similar physical processes may be operating in these different systems.

Journal Article↗
PubMed2000

Plastic membrane electrode for the potentiometric determination of pethidine hydrochloride in pharmaceutical preparations.

A novel poly(vinyl chloride) membrane electrode with dibutyl phthalate as plasticizer based on the pethidine-tetraphenylborate ion-association complex as ion-exchange site for the determination of pethidine hydrochloride in injections and tablets was developed. A linear response for 1 x 10(-5) to 1 x 10(-2) mol/L drug with a slope of 51.77 mV/decade was established. The optimum pH range was 2-8. The lower detection limit was 2.18 x 10(-6) mol/L. There were negligible interferences from a number of inorganic and organic cations and some common drug excipients. The electrode proposed had been successfully applied to determine pethidine hydrochloride in tablets and injections. The results correlated well with those obtained by the United States Pharmacopoeia standard procedure.

Calibration↗
PubMed2000

Human oviductal cells produce a factor(s) that maintains the motility of human spermatozoa in vitro.

OBJECTIVE: To characterize in part the factor(s) in conditioned medium (CM) that maintains sperm motility after human oviductal cell culture. DESIGN: Controlled, experimental, laboratory study. SETTING: University-based gynecology unit. PATIENT(S): Fallopian tubes were obtained from patients who underwent tubal ligation or hysterectomy. Semen with normal sperm parameters was obtained from men who visited subfertility clinics. INTERVENTION(S): Spermatozoa were incubated with CM and their motility was evaluated by a computer-aided sperm analysis system. MAIN OUTCOME MEASURE(S): Curvilinear velocity, straight-line velocity, average path velocity, linearity, amplitude of lateral head displacement, beat cross-frequency, and percentage of spermatozoa that exhibited hyperactivation. RESULT(S): Compared with their baseline motility (0 hour), spermatozoa incubated with CM maintained various motility parameters for a longer period than did control spermatozoa. All the motility parameters of the CM-treated spermatozoa were higher than those of the control spermatozoa at the same time point. This effect of CM was dose-dependent and increased with the duration of incubation. The effect was stable at 56 degrees C but was not observed after 100 degrees C heat treatment. Trypsin, but not proteinase K, abolished the effect. A fraction with a molecular weight of <3 kd in the CM was responsible for the observed effect. CONCLUSION(S): Human oviductal cells produce a peptide(s) that maintains sperm motility.

Animals↗
PubMed2000

Effects of human follicular fluid on the capacitation and motility of human spermatozoa.

OBJECTIVE: To investigate the capacitation and motility kinetics of spermatozoa treated with human follicular fluid (FF). DESIGN: Controlled, experimental laboratory study. SETTING: University-based gynecology unit. PATIENT(S): Human FF was collected from women undergoing assisted reproductive treatment. Semen samples were obtained from men visiting subfertility clinics. INTERVENTION(S): Spermatozoa were incubated with human FF under various experimental conditions. Spermatozoa incubated with Earle's balanced salt solution were used as the control. MAIN OUTCOME MEASURE(S): Chlortetracycline staining patterns and sperm motility parameters. RESULT(S): The rate of capacitation in the human FF-treated spermatozoa was significantly higher than that in the control spermatozoa after 1 hour and 3 hours of treatment. The percentage of acrosome-reacted spermatozoa also was significantly higher after human FF treatment than after control treatment. These effects of human FF were dose-dependent. Human FF-treated spermatozoa maintained their velocities at the zero-hour level for 5 hours, whereas the velocities of the control spermatozoa decreased significantly after 1 hour. Human FF treatment significantly increased the beat cross-frequency above the rate at zero hour for 5 hours. The hyperactivation of the human FF-treated spermatozoa remained stable for 3 hours, whereas that of the control spermatozoa decreased significantly after 1 hour of incubation. Significantly more human FF-treated spermatozoa underwent hyperactivation than did control spermatozoa after 1 hour and 3 hours of treatment. The effects of human FF on beat cross-frequency and hyperactivation were dose-dependent. CONCLUSION(S): Human FF promotes capacitation and the acrosome reaction within a short period. It also stimulates or maintains various sperm motility parameters.

Acrosome Reaction↗
PubMed2000

Polychlorinated dibenzo-p-dioxins and dibenzofurans in sediment, soil, fish, shellfish and crab samples from Tokyo Bay area, Japan.

Concentrations of tetra- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans in samples collected in or near Tokyo Bay, Japan, with a densely inhabited catchment area, were congener-specifically determined and discussed. Analyzed in this study were samples of surface sediment covering the whole bay area, reference soil representing atmospheric impact, and fish, shellfish and crab commonly consumed as food. The range of concentrations were comparable to or higher than those in other parts of Japan. The origins of these compounds in the catchment area of the bay were investigated in terms of homolog and isomeric compositions in the sediment samples. Biota-sediment accumulation factors for benthic species declined as the degree of chlorination increased.

Animals↗
PubMed2000

Kinetic studies of imidazole and its methyl derivative binding to metmyoglobin: effects of substitute methyl on the binding affinity.

The binding of imidazole and imidazole derivatives (4- and 2-MeIm) to the metMb was studied by 1H NMR spectroscopy to elucidate the effects of different methyl substitution positions on the affinity and kinetics of binding to metMb. These exogenous ligands can form stable complexes with metMb except 2-MeIm. Kinetics and equilibrium data for the binding of imidazole and 4-MeIm to metMb have been obtained by 2D EXSY, and the reasons for the different affinity are also discussed.

Animals↗
PubMed2000

Controlling global stochasticity in the standard map.

A method for controlling global stochasticity in two-dimensional Hamiltonian systems is proposed in a model of the standard map. We demonstrate that this control method can stabilize global stochasticity into regular motion running in limited regions. The method is robust under the presence of weak external noise. Noise-induced intermittency can be found in the case of large noise strength. This is a new type of intermittency similar to the recently discovered in-out intermittency.

Journal Article↗
PubMed2000

Controlling hamiltonian chaos by adaptive integrable mode coupling

The adaptive integrable mode coupling method is proposed to control two-dimensional Hamiltonian chaos. We demonstrate that this control method can stabilize chaotic motions into regular ones in a model of the standard map. Global stochasticity can be removed from the phase space by the control being switched on and off.

Journal Article↗