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Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 271 records · Page 15Linked to original sources
PubMed2000

Quantitative digitography (QDG): a sensitive measure of digital motor control in idiopathic Parkinson's disease.

This study introduces a new method for studying, quantitatively, the dynamics of finger movement using data obtained from sequences of key strikes on a computer-interfaced piano keyboard. We have called this quantitative digitography (QDG). This initial article introduces the method in a group of patients with Parkinson's disease and in a group of healthy subjects using simple, repetitive, alternating finger-tapping for 60 seconds. Patients with idiopathic Parkinson's disease (IPD) were studied "ON" and "OFF" dopaminergic medication before and after pallidotomy. Customized software allowed the independent analysis of key strike velocity, duration of key strike, and frequency of tapping along with a quantitative measure of the regularity of performance. Quantitative measures of the improvement in performance after medication are presented for each parameter of movement. The technique also reveals correlates of some clinical phenomena of the temporal disturbances of repetitive motion in IPD, such as fatigue, tremor, freezing, and festination. We demonstrate that the performance of 60 seconds of alternating finger tapping on a computerized keyboard yields objective measures of motor performance that are significantly different in patients with IPD "OFF" when compared with "ON" medication and when compared with healthy subjects. This is the first time that such a method has been used in the measurement of specific kinematics of digital motion in Parkinson's disease. The equipment is inexpensive and portable and the data are rapidly and easily collected, making it suitable for the outpatient setting.

Adult↗
PubMed2000

Characterization of zebrafish full-length prothrombin cDNA and linkage group mapping.

In this paper, we report the complete cDNA sequence of zebrafish prothrombin. The cDNA sequence predicts that zebrafish prothrombin is synthesized as a pre-proprotein consisting of a Gla domain, two kringle domains, and a two-chain protease domain. Zebrafish prothrombin is structurally very similar to human and other vertebrate prothrombins. Zebrafish and human prothrombin share 53% amino acid identity whereas zebrafish and hagfish prothrombin share 51% identity. Amino acid alignments of various prothrombins identified conservation of many of the functional/structural motifs suggesting that the vertebrate prothrombins may have similar functions. The three-dimensional structure of prothrombin predicted by homology modeling also revealed that the prothrombin fragment 1 and the catalytic domain structures are well conserved except for the insertion of an extra 7-amino-acid loop in the connecting region (CR) between the Gla and kringle I domain of fragment 1. Linkage analysis revealed that the prothrombin gene locus on linkage group 7 in zebrafish is syntenic to the human chromosome 11-prothrombin region suggesting its preservation through evolution. The availability of this cDNA sequence in zebrafish adds to our knowledge of the zebrafish hemostatic system and provides support for the view that similarities between zebrafish and mammalian coagulation exist, thus underscoring the relevance of the zebrafish model for studying human hemostasis.

Amino Acid Sequence↗
PubMed2000

Electron spin-lattice relaxation rates for high-spin Fe(III) complexes in glassy solvents at temperatures between 6 and 298 K.

The temperature dependence of spin-lattice relaxation rates was analyzed for four high-spin nonheme iron proteins between 5 and 20 K, for three high-spin iron porphyrins between 5 and 118 K, and for four high-spin heme proteins between 5 and 150 to 298 K. For the nonheme proteins the zero-field splittings, D, are less than 0.7 cm(-1), and the relaxation is dominated by the Orbach and Raman processes. For the iron porphyrins and heme proteins D is between 4 and 12 cm(-1) and the relaxation is dominated by the Orbach process between about 5 and 100 K and by a local mode at higher temperatures. The relaxation rates for the heme proteins in glassy matrices extrapolated to values at room temperature that are similar to values obtained by NMR relaxivity in fluid solution. This similarity suggests that for high-spin Fe(III) heme proteins with effective intramolecular spin-lattice relaxation processes, the additional motional freedom gained when a relatively large protein goes from glassy solid to liquid solution at room temperature has little impact on spin-lattice relaxation.

Animals↗
PubMed2000

Pre-clinical experimental studies of indomethacin-releasing copper intrauterine device.

Effects of two types of intrauterine device (IUD) on the prostaglandins and endothelin (ET) in uterus and on the endometrial morphology in rats and rabbits, and Cu2+ releasing amounts of both IUDs in vitro were observed. The results showed that the inhibiting action of the indomethacin-releasing copper IUD (FICu-IUD) on the PGI2 was stronger than that on the TXA2, the ratio of 6-keto-PGF1 alpha/TXB2 was reduced with the increase of the doses. There were significant differences between the groups. The FICu-IUD could inhibit the rising of the ET level and lighten the endometrial impairment caused by the FCu-IUD, and promote copper ion release. It was suggested that indomethacin released by FICu-IUD could effectively reduce abnormal uterine bleeding.

Animals↗
PubMed2000

Covalent attachment of DNA to glass supports using a new silane coupling agent and chemiluminescent detection.

A new kind of silane coupling agent, N-(beta-aminoethyl)-gamma-aminopropyl triethoxysilane, was used for DNA direct attachment on the surfaces of glass supports, then the immobilized DNA was hybridized with horseradish peroxidase (HRP)-labeled probe, and detected by using enhanced chemiluminescent method. In comparison with gamma-aminopropyl triethoxysilane, the detection limits (S/N) of DNA were 10 pg and 75 pg respectively. Several experimental conditions of DNA attach-ING to glass supports were investigated, and the system of hybridization of nucleic acid on the surfaces of glass supports was developed.

DNA↗
PubMed2000

Clinical application of surface mode on three-dimensional ultrasonography: a preliminary study.

To investigate the methology and evaluate the clinical value of surface mode on three-dimensional ultrasonography (3DUS) in static anatomical structures, 62 patients with various diseases were studied. The equipment used here was Voluson 530D 3DUS imaging system and 3D volume transducer with frequency being 3.0-5.0 MHz. The 3DUS rendering method was surface mode. The results showed that: 1) Surface mode of 3DUS could demonstrate clearly the anatomical characteristics of the region-of-interest (ROI) and the inner wall of lesions or organs that contained fluid. The anatomic details, such as location, size, shape, and number of the ROI, could be visualized intuitively; 2) The outer anatomic features (e.g. contour, edge, configuration, etc.) of some organs or lesions surrounded by fluid could be displayed clearly. It could be concluded that surface mode on 3DUS could provide more diagnostic information than two-dimensional ultrasonography (2DUS) in some cases and could served as a beneficial supplement to 2DUS in clinical practice.

Adolescent↗
PubMed2000

Invasive cytotrophoblasts manifest evidence of oxidative stress in preeclampsia.

In preeclampsia, poor placental perfusion may result in maternal endothelial dysfunction, but the pathways involved are largely unknown. Candidate placental mediators include products of oxidative stress released into the maternal circulation. Xanthine oxidase has been implicated in postischemic-reperfusion injury via the generation of superoxide anion radicals (superoxide; O(2)(.-)) and hydrogen peroxide. We examined placentas and placental bed curettings and/or biopsies from preeclamptic control pregnant women to test the hypothesis that xanthine oxidase is a mediator of oxidative stress in placentas from women with preeclampsia. The expression of xanthine dehydrogenase/xanthine oxidase holoenzyme and the activity of xanthine oxidase, the isoform known to generate reactive oxygen species, were increased in a subpopulation of cytotrophoblasts of preeclamptic women. Additionally, the expression of superoxide dismutase, which would scavenge superoxide produced by xanthine oxidase, was reduced in the same cells. Furthermore, fluorescence immunostaining for nitrotyrosine, which was suggestive of superoxide-nitric oxide interactions to form peroxynitrite anion (ONOO(-)) in vivo, was increased in these cells and in villous vessels. Thus, our data indicate an increased capacity of placental cells to generate reactive oxygen species in preeclampsia.

Adult↗
PubMed2000

Thrombospondin-2 gene expression and protein localization during embryonic mouse palate development.

The mammalian palate develops from projections of the paired maxillary processes termed palatal shelves. Shelf growth is an essential in normal palatal morphogenesis. Mesenchymal proliferation in the palatal shelves is modulated by transforming growth factor-1 (TGF-1), among other growth factors. Several pathways effect TGF-beta activation, including one which utilizes thrombospondin (TSP). TSP-1 is a major activator of TGF-beta in vivo and has been localized in head mesenchyme, including palates. TSP-2 appears to inhibit TSP-1 activation of latent TGF-beta by competitively binding the latent TGF-beta. Here the TSP-2 mRNA transcript and the immunolocalization of TSP-2 protein with progressive palatogenesis were quantified. There was a significant (p < 0.05) decline of TSP-2 transcript with palatal maturation; there was no evidence correlating the TSP-2 transcription with the amount of activated TGF-beta. At the vertical shelf stage of palatogenesis, TSP-2 protein was found throughout the extracellular matrix of shelf mesenchyme. By the horizontal shelf stage, TSP-2 protein was principally localized to the ossification centres of the developing maxilla, both in extracellular matrix and bone; far less was seen in palatal shelves proper. These results suggest that TSP-2 is multifunctional during embryonic palate formation.

Animals↗
PubMed2000

Interspin distances in spin-labeled metmyoglobin variants determined by saturation recovery EPR.

Saturation recovery (SR) electron paramagnetic resonance was used to determine the distance between iron and nitroxyl for spin-labeled metmyoglobin variants in low-spin and high-spin states of the Fe(III). The interspin distances were measured by analyzing the effect of the heme iron on the spin-lattice relaxation rates of the nitroxyl spin label using the modified Bloembergen equation for low-spin species, and an analogue of the Bloembergen equation for high-spin species. Insight simulations of the spin-labeled protein structures also were used to determine the interspin distances. The distances obtained by SR for high-spin and low-spin complexes with 15-20 A interspin distances, for low-spin CN(-) and high-spin formate adducts at distances up to about 30 A, and results from Insight calculations were in good agreement. For variants with 25-30 A interspin distances, the distances obtained by SR for the fluoride adducts were shorter than observed for the CN(-) or formate adducts or predicted by Insight simulations. Of the heme axial ligands examined (CN(-), imidazole, F(-), and formate), CN(-) is the best choice for determination of iron-nitroxyl distances in the range of 15-30 A.

Amino Acid Substitution↗
PubMed2000

Protein motions at zero-total angular momentum: the importance of long-range correlations.

A constant-energy molecular dynamics simulation is used to monitor protein motion at zero-total angular momentum. With a simple protein model, it is shown that overall rotation is possible at zero-total angular momentum as a result of flexibility. Since the rotational motion is negligible on a time scale of 1000 reduced time units, the essentially rotation-free portion of the trajectory provides an unbiased test of the common approximate methods for separating overall rotation from internal motions by optimal superposition. Removing rotation by minimizing the root-mean-square deviation (RMSD) for the entire system is found to be more appropriate than using the RMSD for only the more rigid part of the system. The results verify the existence of positive cross-correlation in the motions of atoms separated by large distances.

Models, Molecular↗
PubMed2000

Structure of basic phospholipase A2 from Agkistrodon halys Pallas: implications for its association, hemolytic and anticoagulant activities.

The basic phospholipase A2 (PLA2) from the venom of Agkistrodon halys Pallas is a potent hemolytic toxin and anticoagulant. Crystal structure of the enzyme complexed with detergent n-octyl beta-D-glucopyranoside (beta-OG) in monoclinic crystal form has been determined to 2.6 A resolution. Beta-OG molecules were found in the hydrophobic channels of the enzyme. SDS-PAGE and dynamic light scattering measurements showed that the enzyme had a strong tendency to dimerise in aqueous solution. In the crystal structure the enzyme molecules associate into a tetramer with pseudo 222 symmetry, and the interfacial recognition site linked dimers constituting the tetramer have intensive interface interactions, and may be stable in solution. The structure reveals a unique positively charged face at the C-terminal region and a characteristic non-cationic 'anticoagulant' region (53-77). The face is supposed to be the hemolytic site, and based on sequence and structure comparison residues Trp70 and Glu53 instead of the basic residues in 'anticoagulant' region might play an important role in the anticoagulant activity.

Agkistrodon↗
PubMed2000

Parental underestimates of adolescent risk behavior: a randomized, controlled trial of a parental monitoring intervention.

OBJECTIVES: To develop and evaluate an intervention (ImPACT) seeking to increase monitoring (supervision and communication) by parents and guardians of African-American youth regarding high risk and protective behaviors; and to develop an instrument to assess parental monitoring, the Parent-Adolescent Risk Behavior Concordance Scale. DESIGN/INTERVENTION: This research was a randomized, controlled longitudinal study. Baseline (preintervention), and 2 and 6 months postintervention data were obtained via a talking MacIntosh computer regarding youth and parent perceptions of youth involvement in 10 risk behaviors, parental monitoring and youth-parent communication, and condom-use skills. Intervention parents and youth received the ImPACT program and a video emphasizing parental supervision and discussion, followed by a structured discussion and role-play emphasizing key points. Control parents and youth received an attention-control program on goal-setting, which also included an at-home video and discussion. PARTICIPANTS: A total of 237 parents and one each of their youth (ages 12-16 years) recruited from eight public housing developments located in a city in the mid-Atlantic region. RESULTS: Similarity of youth and parental reporting on the Parent-Adolescent Risk Behavior Concordance Scale was positively correlated with protective behaviors, perceived parental monitoring, and good parent-youth communication. At baseline, parents significantly underestimated their youth's risk behaviors. However, 2 and 6 months postintervention, the ImPACT program increased similarity of reports by youth and their parents of youth involvement in risk and protective behaviors. In addition, at 6 months postintervention, intervention (compared to control) youths and parents also demonstrated higher levels of condom-use skills. CONCLUSION: Parental monitoring interventions such as ImPACT should be given to parents in conjunction with more traditional youth-centered risk-reduction interventions.

Adolescent↗
PubMed2000

Green up-conversion emission in Er3+:BaTiO3 sol-gel powders.

Bright green emissions at 549 and 526 nm have been observed from sol-gel derived Er3+:BaTiO3 powders upon excitations at two near infrared (NIR) wavelengths of 973 and 816 nm. The decay characteristics were measured and studied. It was found that the predominant emission at 549 nm has very different lifetimes upon excitation at 973 and 816 nm, which was explained by the mechanisms of excited state absorption (ESA) of individual Er3+ ion and cooperative energy transfer (CET) between two near Er3+ ions for the up-conversion emission. Analysis also showed that 973-nm excitation is more effective for the green up-conversion emission.

Barium Compounds↗
PubMed2000

Attachment kinetics of Vero cells onto CT-3 microcarriers.

The effects of cell seeding density, microcarrier concentration, agitation speed and age of seeding cells on the rate of cell attachment to the surface of CT-3 microcarriers were investigated. It was shown that the attachment followed first-order kinetics. When either the cell seeding density or the microcarrier concentration was increased, the kinetic constant increased due to an increase in the probability of collision between cells and microcarriers. However, at higher microcarrier concentrations, the increase in the kinetic constant with increasing microcarrier concentration was not significant. Cell attachment was decelerated upon increasing the agitation speed because of the shorter cell-microcarrier contact time. In addition, it was also demonstrated that cell attachment occurred more efficiently when seeding cells from the middle or early exponential growth phase were used. The process of cell attachment onto CT-3 microcarriers was investigated, and our results showed that the attachment stage was the rate-limiting step. These results will facilitate the optimization of the Vero cell culture process.

Journal Article↗
PubMed2000

The interferon-alpha regulation of interferon regulatory factor 1 (IRF-1) and IRF-2 has therapeutic implications in carcinoid tumors.

BACKGROUND: Interferon regulatory factor 1 (IRF-1) has been demonstrated to possess antiproliferative and tumor suppressor functions, on the contrary. IRF-2 has been suggested to induce oncogenetic effect in some cell lines, but not evaluated in tumor patients. PATIENTS AND METHODS: In 35 carcinoid tumor patients, expressions of IRF-1 and IRF-2 were investigated by immunohistochemistry and their values were analyzed with clinical treatment response. In carcinoid tumor cell line, Bonl, effects of IFN-alpha on the expression of both IRF-1 and IRF-2 mRNAs and proteins were determined by Northern blot, RNase protection assays and Western blot analysis. RESULTS: IFN-alpha up-regulated the expression of IRF-1 and IRF-2 both in vivo and in vitro. In carcinoid tumors, IFN-alpha treatment led to a significant increase in the expression of IRF-1 (P < 0.001) and IRF-2 (P < 0.001). Moreover, the IRFs induction was correlated with the clinical response of IFN-alpha treatment, although their baseline values were not predictive. In addition, expressions of IRF-1 and IRF-2 were significantly correlated with the p68 kinase expression (P = 0.032 and P = 0.0176, respectively) and the expression of IRF-1 protein was positively correlated with that of IRF-2 (r = 0.671, P = 0.0001) tested in the same specimens. CONCLUSIONS: IRF-1 as well as IRF-2 have therapeutic implications in carcinoid tumors during treatment with interferon-alpha and IRFs induction might be used as indicators of response to treatment with interferon-alpha.

Carcinoid Tumor↗
PubMed2000

Regulation of cytoplasmic dynein behaviour and microtubule organization by mammalian Lis1.

Whereas total loss of Lis1 is lethal, disruption of one allele of the Lis1 gene results in brain abnormalities, indicating that developing neurons are particularly sensitive to a reduction in Lis1 dosage. Here we show that Lis1 is enriched in neurons relative to levels in other cell types, and that Lis1 interacts with the microtubule motor cytoplasmic dynein. Production of more Lis1 in non-neuronal cells increases retrograde movement of cytoplasmic dynein and leads to peripheral accumulation of microtubules. These changes may reflect neuron-like dynein behaviours induced by abundant Lis1. Lis1 deficiency produces the opposite phenotype. Our results indicate that abundance of Lis1 in neurons may stimulate specific dynein functions that function in neuronal migration and axon growth.

Animals↗
PubMed2000

Expression of the plant cyclin-dependent kinase inhibitor ICK1 affects cell division, plant growth and morphology.

The plant CDK inhibitor ICK1 was identified previously from Arabidopis thaliana with its inhibitory activity characterized in vitro. ICK1 displayed several structural and functional features that are distinct from known animal CDK inhibitors. Despite the initial characterization, there is no information on the functions of any plant CDK inhibitor in plants. To gain insight into ICK1 functions in vivo and the role of cell division during plant growth and development, transgenic plants were generated expressing ICK1 driven by the cauliflower mosaic virus 35S promoter. In comparison to control plants, growth was significantly inhibited in transgenic 35S-ICK1 plants, with some plants weighing <10% of wild-type plants at the 3 week stage. Most organs of 35S-ICK1 plants were smaller. There were also modifications in plant morphology such as shape and serration of leaves and petals. The changes were so drastic that 35S-ICK1 plants with strong phenotype no longer resembled wild-type plants morphologically. Analyses showed that increased ICK1 expression resulted in reduced CDK activity and reduced the number of cells in these plants. Cells in 35S-ICK1 plants were larger than corresponding cells in control plants. These results demonstrate that ICK1 acts as a CDK inhibitor in the plant, and the inhibition of cell division by ICK1 expression has profound effects on plant growth and development. They also suggest that alterations of plant organ shape can be achieved by restriction of cell division.

Arabidopsis↗