Biomedical subjects

X Hang

Publications and source records attributed to X Hang.

9 recordsLinked to original sources

PubMed2005

Production and characterisation of gilthead sea bream (Sparus auratus) recombinant parathyroid hormone related protein.

The production and purification of gilthead sea bream recombinant parathyroid hormone related protein [sbPTHrP(1-125)] using an Escherichia coli system and one step purification process with continuous elution gel electrophoresis is reported. The cDNA encoding sbPTHrP(1-125) was cloned into a prokaryotic expression vector pET-11a. The recombinant plasmid was used to transfect E. coli BL21(DE3) pLysS and sbPTHrP(1-125) synthesis was induced by addition of 1mM isopropyl-beta-d-thiogalactopyranoside. The rapid one step isolation method gave pure sbPTHrP(1-125) as judged by SDS-PAGE and yielded up to 40mg/L of culture medium (3.3mg protein/g of bacteria). The bioactivity of recombinant sbPTHrP(1-125) assessed using an in vitro scale bioassay was found to be equipotent to PTHrP(1-34) in stimulating cAMP accumulation. Assessment of the immunological reactivity of the isolated protein by Western blot revealed it cross-reacts with antisera specific for the N-terminal and C-terminal region of PTHrP. In a radioimmunoassay specific for piscine N-terminal (1-34aa) PTHrP, the recombinant sbPTHrP(1-125) was equipotent with PTHrP(1-34) in displacing labelled (125)I-PTHrP(1-36) PTHrP from the antisera. The availability of recombinant sbPTHrP will allow the development of region specific assays and studies aimed at defining post-secretory processing of this protein and its biological activity in fish.

Amino Acid Sequence↗

PubMed2005

Methyl bromide as a quarantine treatment for Anoplophora glabripennis (Coleoptera: Cerambycidae) in regulated wood packing material.

Anoplophora glabripennis (Motschulsky), has recently (since 1996) established in limited infestations near several cities in the United States. A. glabripennis was probably introduced into the United States with solid wood packing or dunnage. During 2001, we evaluated the current APHIS Schedule T404-b-1-1 for methyl bromide (MeBr) fumigation. Fumigations were conducted in 432-liter Lexan chambers inside a 6.1-m refrigerated container. Each fumigation consisted of 12 high-moisture, naturally infested Populus spp. timbers. We fumigated wood for 24 h at 4.4 degrees C (80 g/m3), 10.0 degrees C (64 g/m3), 15.6 degrees C (56 g/m3), and 21.1 degrees C (48 g/m3). All schedule doses resulted in 100% kill of A. glabripennis larvae. During 2002, we conducted additional fumigations to determine the basic toxicity of MeBr to A. glabripennis larvae in solid wood timbers of 10 by 10 by 115-cm size. Probit analysis estimated the CxT product at 99.0, 99.9, 99.99, and 99.99683% kill (probit-9). The probit-9 values for CxT were 1,196.1, 918.7, 642.4, and 362.4 g-h/m3 at 4.4, 10.0, 15.6, and 21.1 degrees C, respectively. Applied doses to achieve this level of control were estimated to be 119.6, 82.7, 56.0, and 32.2 g/m3, respectively. These applied doses are satisfactory for wood as a commodity with wood load factors of approximately 25% and may be higher than necessary for container fumigation where sorptive wood load as crating or pallets may only be 5% or less. The APHIS Schedule T404-b-1-1 is adequate if extended for 24 h and should be amended to include intermediate doses at 10.0 and 15.6 degrees C, thus reducing the use of MeBr at these temperatures.

Animals↗

PubMed2002

A geometric deformable model for echocardiographic image segmentation.

Gradient vector flow (GVF), an elegant external force for parametric deformable models, can capture object boundaries from both sides. A new geometric deformable model is proposed that combines GVF and the geodesic active contour model. The level set method is used as the numerical method of this model. The model is applied for echocardiographic image segmentation.

Algorithms↗

PubMed2001

PCR cloning of type II polyhydroxyalkanoate biosynthesis genes from two Pseudomonas strains.

Two polyhydroxyalkanoate synthase genes, phaC1 from Pseudomonas pseudoalcaligenes HBQ06 and phaC2 from Pseudomonas nitroreducens 0802, were cloned using a PCR cloning strategy based on the type II pha loci property of Pseudomonas strains. The complete open reading frames (ORFs) of phaC1 (P. nitroreducens HBQ06) and phaC2 (P. nitroreducens 0802) were identified from the PCR products. Using the sequence information, the complete PHA synthase genes were PCR cloned directly from the genomic DNA and expressed in Escherichia coli as confirmed by Fourier transform-infrared spectroscopy and gas chromatography. The differences between PhaC1 and PhaC2 were analyzed and the two proteins were suggested to contain different functions and evolution history.

Acyltransferases↗

PubMed2001

Compression of echocardiographic scan line data using wavelet packet transform.

An efficient compression strategy is indispensable for digital echocardiography. Previous work has suggested improved results utilizing wavelet transforms in the compression of 2D echocardiographic images. Set partitioning in hierarchical trees (SPIHT) was modified to compress echocardiographic scanline data based on the wavelet packet transform. A compression ratio of at least 94:1 resulted in preserved image quality.

Algorithms↗

PubMed2000

[Study of modeling and simulation of the multi-branch cardiovascular system].

By the Power Band Graph(PBG) method, this paper presents a computer simulation model of the multi-branch cardiovascular circulation system, which describes the blood fluid dynamic law in the cardiovacular system by the state equation. The model gives a minute description on physiological characters of cardiovascular circulation system (CVS). An integrate computer model on CVS has been established. The model can simulate physiological characters of cardiovascular circulation system and get the simulation data and the curves of CVS hemodynamics variables. The model can be used widely in the field of physiological system simulation study, medical study, and computer-aided instruction.

Computer Simulation↗

PubMed2000

Compression of real time volumetric echocardiographic data using modified SPIHT based on the three-dimensional wavelet packet transform.

Real-time three-dimensional echocardiography has been introduced to provide improved quantification and description of cardiac function. Data compression is desired to allow efficient storage and improve data transmission. Previous work has suggested improved results utilizing wavelet transforms in the compression of medical data including 2D echocardiogram. Set partitioning in hierarchical trees (SPIHT) was extended to compress volumetric echocardiographic data by modifying the algorithm based on the three-dimensional wavelet packet transform. A compression ratio of at least 40:1 resulted in preserved image quality.

Aerospace Medicine↗

PubMed2000

Impact of temporal resolution on flow quantification by real-time 3D color Doppler echocardiography: numerical modeling and animal validation study.

Real-time, 3D color Doppler echocardiography (RT3D) is capable of quantifying flow at the LV outflow tract (LVOT). However, previous works have found significant underestimation for flow rate estimation due to finite scanning time (ST) of the color Doppler. The authors have, therefore, developed a mathematical model to correct the impact of ST on flow quantification and validated it by an animal study. Scanning time to cover the entire cross-sectional image of the LVOT was calculated as 60 ms, and the underestimation due to temporal averaging effect was predicted as 18 +/- 7%. In the animal experiment, peak flow rates were obtained by spatially integrating the velocity data front the cross-sectional color images of the LVOT. By applying a correction factor, there was an excellent agreement between reference flow rate by an electromagnetic flow meter and RT3D (angstroms=-5.6 ml/s, r=0.93), which was significantly better than without correction (p<0.001). Real-time, color 3D echocardiography was capable of quantifying flow accurately by applying the mathematical correction.

Animals↗

PubMed1995

The lef-3 gene of Autographa californica nuclear polyhedrosis virus encodes a single-stranded DNA-binding protein.

The Autographa californica nuclear polyhedrosis virus (AcNPV) replicates in the nuclei of infected cells and encodes several proteins required for viral DNA replication. As a first step in the functional characterization of viral replication proteins, we purified a single-stranded DNA-binding protein (SSB) from AcNPV-infected insect cells. Nuclear extracts were chromatographed on single-stranded DNA agarose columns. An abundant protein with an apparent molecular weight of 43,000 was eluted from the columns at 0.9 to 1.0 M NaCl. This protein was not evident in extracts prepared from control cells, suggesting that the SSB was encoded by the virus. SSB bound to single-stranded DNA in solution, and binding was nonspecific with respect to base sequence, as single-stranded vector DNA competed as efficiently as single-stranded DNA containing the AcNPV origin of DNA replication. Competition binding experiments indicated that SSB showed a preference for single-stranded DNA over double-stranded DNA. To determine whether SSB was encoded by the lef-3 gene of AcNPV, the lef-3 open reading frame was cloned under the control of the bacteriophage T7 promoter. Immunochemical analyses indicated that LEF-3 produced in bacteria or in rabbit reticulocyte lysates specifically reacted with antiserum produced by immunization with purified SSB. Immunoblot analyses of infected cell extracts revealed that SSB/LEF-3 was detected by 4 h postinfection and accumulated through 48 h postinfection.

Animals↗