Biochemical analysis using high-resolution magic angle spinning NMR spectroscopy distinguishes lipoma-like well-differentiated liposarcoma from normal fat.
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Adipose Tissue↗
Biomedical subjects
J H Chen
Publications and source records attributed to J H Chen.
Local thermodynamic stability scores are well represented by a non-central student's t distribution.
Local folding in mRNAs is closely associated w ith biological functions. In this study, we reveal the whole distribution of local thermodynamic stability in the complete genome of the poliovirus P3/Leon/37 and the single-stranded RNA sequences that corresponds to the nucleotide sequence of the complete genome sequence (1 667 867 bp) of Helicobacter pylori (H. pylori) strain 26695. Local thermodynamic stability in the RNA sequences is measured by two standard z -scores, significance score and stability score. To estimate the distribution of thermodynamic stability, a model based on the non-central Student's t distribution has been developed. Significant patterns of extremes that are either much more stable or unstable than expected by chance are detected. Our results indicate that the highly stable and statistically more significant folding regions are predominantly in non-coding sequences in the two genome sequences. Moreover, the highly unstable folding regions, on the contrary, are predominantly in the protein coding sequences of H. pylori. The observed differences across the complete genomic sequences are statistically very significant by a chi2-test. These extreme patterns may be useful in searching for target sequences for long-chain antisense RNA and for locating potential RNA functional elements involved in the regulation of gene expression including translation, mRNA localization and metabolism.
Animals↗
Metal complexes of N-p-nitrobenzoylamido- meso-tetraphenylporphyrin: cis-acetato-N-p-nitrobenzoylimido-meso- tetraphenylporphyrinatothallium(III) and N-p-nitrobenzoylimido-meso- tetraphenylporphyrinatonickel(II).
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Journal Article↗
On the pyrolysis kinetics of scrap automotive tires.
Pyrolysis kinetics of scrap tires of passenger car and truck have been investigated thermogravimetrically under heating rates of 5, 10, 20 and 30K/min and temperature range 373-1273K in nitrogen. The results show that the initial reaction temperatures are 482-521K for the tire of passenger car and 458-511K for truck tire. Both tires exhibit similar behaviors that the initial reaction temperature decreases, but reaction range and reaction rate increase when heating rate is increased. The overall rate equation for each tire can be modeled satisfactorily by a simple one equation from which the kinetic parameters such as the activation energy (E), the pre-exponential factor (A), and the reaction order (n) of unreacted material based on Arrhenius form are determined using Friedman's method. The results show that two tires behave similarly and the average kinetic parameters of two tires are E = 147.95 +/- 0.21kJ/mol, A = (6.295 +/- 1.275)x10(10)min(-1), and n = 1.81 +/- 0.18. The predicted rate equations compare fairly well with the measured data.
Incineration↗
Inhibition of LZIP-mediated transcription through direct interaction with a novel host cell factor-like protein.
Host cell factor 1 (HCF-1) is a cellular transcriptional coactivator which coordinates the assembly of enhancer complex through direct interactions with viral and cellular trans-activators such as VP16, Oct-1, LZIP, and GA-binding protein. These interactions are mediated by the beta-propeller domain comprising the first 380 residues of HCF-1 with six kelch repeats. Here we describe the identification and characterization of a novel HCF-like kelch repeat protein, designated HCLP-1. HCLP-1 is a ubiquitously expressed nuclear protein which is composed almost entirely of a six-bladed beta-propeller. HCLP-1 selectively interacts with LZIP but not with VP16. The physical interaction between HCLP-1 and LZIP leads to the repression of the LZIP-dependent transcription. The HCLP-1-binding domain of LZIP maps to residues 109-315, which contain the bZIP DNA-binding motif. Electrophoretic mobility shift assay demonstrates that HCLP-1 indeed interferes with the binding of LZIP to its DNA target. Thus, HCLP-1 serves a transcriptional co-repressor function mediated through its inhibitory interaction with the LZIP transcription factor. Our findings suggest a new mechanism for transcriptional regulation by HCF-like proteins.
Amino Acid Sequence↗
Regulation of ecdysteroid signaling: cloning and characterization of ecdysone oxidase: a novel steroid oxidase from the cotton leafworm, Spodoptera littoralis.
One route of inactivation of ecdysteroids in insects involves ecdysone oxidase-catalyzed conversion into 3-dehydroecdysteroid followed by irreversible reduction by 3-dehydroecdysone 3alpha-reductase to 3-epiecdysone. We have purified from Spodoptera littoralis the first ecdysone oxidase and subjected it to limited amino acid sequencing. A reverse-transcriptase polymerase chain reaction-based approach has been used to clone the cDNA (2.8 kilobases) encoding this 65-kDa protein. Northern blotting showed that the mRNA transcript was expressed in midgut during the prepupal stage of the last larval instar at a time corresponding to an ecdysteroid titer peak. Conceptual translation of the ecdysone oxidase cDNA and data base searching revealed that the enzyme is an FAD flavoprotein that belongs to the glucose-methanol-choline oxidoreductase superfamily. Ecdysone oxidase represents the only oxidase in eukaryotic animals known to catalyze oxygen-dependent oxidation of steroids; by contrast, oxidation of steroids in vertebrates occurs via NAD(P)(+)-linked dehydrogenases. The injection of RH-5992, an ecdysteroid agonist, induced the transcription of ecdysone oxidase, suggesting that ecdysone oxidase is an ecdysteroid-responsive gene. The gene encoding this enzyme, consisting of five exons, has also been isolated. Sequences similar to the binding motifs for Broad-Complex and FTZ-F1 have been found in the 5'-flanking region. Southern blotting indicated that ecdysone oxidase is encoded by a single-copy gene. We have determined the kinetic characteristics of this novel recombinant ecdysone oxidase produced using a baculovirus expression system.
3-Hydroxysteroid Dehydrogenases↗
Usefulness of echocardiographic intrapericardial abnormalities in the diagnosis of tuberculous pericardial effusion.
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Diagnosis, Differential↗
Association of elevation of anti-Helicobacter pylori antibody with myocardial ischemic events in coronary artery disease.
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Antibodies, Bacterial↗
The N-terminal leucine-rich regions in Slit are sufficient to repel olfactory bulb axons and subventricular zone neurons.
The Slit proteins are a new family of secreted guidance cues involved in axon guidance and neuronal migration. Each mammalian Slit protein contains >1400 amino acid residues, with four leucine-rich regions (LRRs), nine epidermal growth factor repeats, a laminin G domain, and a C-terminal cysteine-rich domain. A receptor for Slit is the transmembrane protein Roundabout (Robo), whose extracellular part contains five Ig domains and three fibronectin type III repeats. We report here that the LRRs in Slit are sufficient for binding to the Ig domains of Robo. Mutant forms of Slit containing only the LRRs function as chemorepellents for axons projecting from the olfactory bulb both in vitro and in the telencephalon. The LRRs can repel neurons migrating from the anterior subventricular zone (SVZa) to the olfactory bulb in brain slices isolated from neonatal rodents. However, the LRRs do not show repulsive effects on the SVZa neurons migrating in collagen gels. Our results indicate that the same LRRs are sufficient for guiding both axon projection and neuronal migration and suggest that the other regions in the Slit proteins may be involved in regulating the diffusion and distribution of the Slit proteins. The fact that the same domains are involved in guiding axon projection and neuronal migration further strengthens the idea of a conserved guidance mechanism for these important processes.
Amino Acid Motifs↗
Functional mutation in the promoter region of thrombomodulin gene in relation to carotid atherosclerosis.
Thrombomodulin is an important endothelial anticoagulant protein that decreases thrombin activity and activates protein C. Our recent study has shown that the G-33A promoter mutation of thrombomodulin gene is associated with coronary artery disease. This study was conducted to determine whether the G-33A mutation in the promoter region of thrombomodulin gene is a genetic risk factor for ischemic stroke or carotid atherosclerosis. The functional significance of this mutation was also evaluated. We recruited 333 patients (mean age 64 years, 59% male) with ischemic stroke and 257 age- and sex-matched controls. In all study participants, carotid atherosclerosis was assessed by Duplex scanning, and thrombomodulin G-33A promoter mutation was detected by single-strand conformation polymorphism. Luciferase reporter gene assay was used to assess the influence of this mutation on thrombomodulin promoter activity. There was no significant difference in the thrombomodulin G-33A mutation frequency (GA+AA genotypes) between the stroke and the control groups (18.3 vs. 24. 1%, P=0.105). The G-33A mutation frequency was also similar between the study participants with and without carotid atherosclerosis (22.2 vs. 19.8%, P=0.550). When only younger subjects (age </=60 years) were included in the analysis, however, we found the mutation occurred more frequently in participants with carotid atherosclerosis (33.3 vs. 17.3%, odds ratio [OR]=2.38, 95% confidence interval [CI]=1.16-4.90, P=0.027). Multiple logistic regression analyses showed that only diabetes mellitus (OR=3.11, 95% CI=1.33-7.30, P=0.009) and G-33A mutation (OR=2.46, 95% CI=1.14-5.29, P=0.021) were associated independently with carotid atherosclerosis in younger subjects. As assessed by luciferase reporter gene assays, the contructs bearing the G-33A mutation showed a significant decrease (36+/-12%) in transcriptional activity in comparison with the wild type constructs. Our findings suggest that G-33A mutation reduces the thrombomodulin promoter activity and is associated with carotid atherosclerosis in younger subjects.
Aged↗
In vivo magnetic resonance (MR) study of fatty liver: importance of intracellular ultrastructural alteration for MR tissue parameters change.
Fatty liver is thought to have a shorter T1 relaxation time than normal liver tissue, due to the accumulation of triglyceride. Previous studies regarding T1 and T2 relaxation times, however, show widely different results. In order to elucidate the mechanism responsible for the changes and diversity of relaxation times in fatty liver, we created two animal models in 14 rabbits, one acute form (N = 6) and the other chronic form (N = 8). Four rabbits were taken as a control group. Tissue relaxation times and the magnetization transfer (MT) effect of the liver tissue in these two models were measured. The results were correlated with biochemical analysis of water and fat content and histological examination, including findings in light microscopy and electron microscopy. Although the fatty ratio in both forms of fatty liver was similar, their tissue relaxation rate and MT effect were significantly different. The acute form showed prolongation of both T1 and T2 relaxation times (512 +/- 51 msec vs. 710 +/- 95 msec and 39 +/- 1.8 msec vs. 48 +/- 3.7 msec, respectively) and a decrease of the MT effect (50 +/- 5.1% vs. 38 +/- 6.3%), compared to those of the control group and preinduction liver. The chronic form showed shorter T1 and T2 values (526 +/- 36 msec vs. 406 +/- 56 msec and 36 +/- 1.6 msec vs. 33 +/- 2.3 msec, respectively) and a stronger MT effect (21 +/- 0.9% vs. 26 +/- 2.3%). In acute form fatty liver, electron microscopic examination revealed dramatic subcellular changes, such as vesicular transformation, a markedly increased amount of smooth endoplasmic reticulum (SER), and disruption of the crista. These changes were not found in the chronic form fatty liver. From this study, we concluded that the ultrastructural alteration in the subcellular organelles of hepatocyte might play a crucial role for the chameleonic presentation of MR tissue parameters in fatty liver.
Animals↗
IMPACT: image-based physiological artifacts estimation and correction technique for functional MRI.
Functional MRI (fMRI) signal variation induced by respiratory and cardiac motion affects the activation signal and limits the accuracy of analysis. Current physiological motion correction methods require either synchronization with external monitoring of respiration and heartbeat, specialized pulse sequence design, or k-space data. The IMage-based Physiological Artifacts estimation and Correction Technique (IMPACT), which is free from these constraints, is described. When images are acquired fast enough to sample physiological motion without aliasing, respiratory and cardiac signals can be directly estimated from magnitude images. Physiological artifacts are removed by reordering images according to the estimated respiratory and cardiac phases and then subtracting the Fourier-fitted variation from magnitude images. Compared with the k-space-based method, this method can efficiently and effectively reduce the overall signal fluctuation in the brain and increase the activated area. With this new technique, physiological artifacts can be reduced using traditional fMRI pulse sequences, and existing data can be corrected and reanalyzed without additional experiments.
Adult↗
Effect of FGF-1 and FGF-2 on VEGF binding to human umbilical vein endothelial cells.
When FGF-1 or FGF-2 and VEGF were added together, the mitogenic effect of FGF-1 or FGF-2 and VEGF on HUVEC was additive. However, when HUVECs were preincubated for 2 days with 10 ng/ml FGF-1 in the absence of VEGF, the Scatchard plot of [125I]VEGF binding sites was shifted to the right: both affinity classes of VEGF binding sites were equally affected, such that the total number of sites increased twofold. It is suggested that this type of interaction may be related to tumor angiogenesis and wound repair.
Cell Division↗
Bifunctional effects of heparin-binding protein HBp17 on DNA synthesis in cells.
A 17 kD heparin-binding protein (HBp17) has a biphasic dose-dependent effect on DNA synthesis in 3T3 cells. Maximal stimulation of DNA synthesis occurs at 8 ng/ml HBp17, but a half-maximal inhibition occurs at approximately 500 ng/ml. This inhibition can easily be reversed by addition of 400 pg/ml aFGF or 100 pg/ml bFGF, whereas EGF had no effect. This biphasic action of HBp17 was also seen in human umbilical vein endothelial cells (HUVEC), whereas it was not found in the malignant cell line, A431-AJC. The functional relationship between HBp17 and FGF is discussed.
3T3 Cells↗
Validation of diffusion tensor magnetic resonance axonal fiber imaging with registered manganese-enhanced optic tracts.
Noninvasive mapping of white matter tracts using diffusion tensor magnetic resonance imaging (DTMRI) is potentially useful in revealing anatomical connectivity in the human brain. However, a gold standard for validating DTMRI in defining axonal fiber orientation is still lacking. This study presents the first validation of the principal eigenvector of the diffusion tensor in defining axonal fiber orientation by superimposing DTMRI with manganese-enhanced MRI of optic tracts. A rat model was developed in which optic tracts were enhanced by manganese ions. Manganese ion (Mn(2+)) is a potent T1-shortening agent and can be uptaken and transported actively along the axon. Based on this property, we obtained enhanced optic tracts with a T1-weighted spin-echo sequence 10 h after intravitreal injection of Mn(2+). The images were compared with DTMRI acquired with exact spatial registration. Deviation angles between tangential vectors of the enhanced tracts and the principal eigenvectors of the diffusion tensor were then computed pixel by pixel. We found that under signal-to-noise (SNR) of 30, the variance of deviation angles was (13.27 degrees). In addition, the dependence of this variance on SNR obeys stochastic behavior if SNR is greater than 10. Based on this relation, we estimated that an rms deviation of less than 10 degrees could be achieved with DTMRI when SNR is 40 or greater. In conclusion, our method bypasses technical difficulties in conventional histological approach and provides an in vivo gold standard for validating DTMRI in mapping white matter tracts.
Animals↗
Tissue segmentation-assisted analysis of fMRI for human motor response: an approach combining artificial neural network and fuzzy C means.
The authors have developed an automated algorithm for segmentation of magnetic resonance images (MRI) of the human brain. They investigated the quantitative analysis of tissue-specific human motor response through an approach combining gradient echo functional MRI and automated segmentation analysis. Fifteen healthy volunteers, placed in a 1.5 T clinical MR imager, performed a self-paced finger opposition throughout the activation periods. T1-weighted images (WI), T2WI, and proton density WI were acquired for segmentation analysis. Single-slice axial T2* fast low-angle shot (FLASH) images were obtained during the functional study. Pixelwise cross-correlation analysis was performed to obtain an activation map. A cascaded algorithm, combining Kohonen feature maps and fuzzy C means, was applied for segmentation. After processing, masks for gray matter, white matter, small vessels, and large vessels were generated. Tissue-specific analysis showed a signal change rate of 4.53% in gray matter, 2.98% in white matter, 5.79% in small vessels, and 7.24% in large vessels. Different temporal patterns as well as different levels of activation were identified in the functional response from various types of tissue. High correlation exists between cortical gray matter and subcortical white matter (r = 0.957), while the vessel behaves somewhat different temporally. The cortical gray matter fits best to the assumed input function (r = 0.957) followed by subcortical white matter (r = 0.829) and vessels (r = 0.726). The automated algorithm of tissue-specific analysis thus can assist functional MRI studies with different modalities of response in different brain regions.
Adult↗
Antifungal highly oxygenated guaianolides and other constituents from Ajania fruticulosa.
Three highly oxygenated guaianolides were isolated from the aerial parts of Ajania fruticulosa along with 17 known phytochemicals including a triterpene (alpha-amyrin), two plant sterols (beta-sitosterol, daucosterol), four flavonoids (axillarin, centaureidin, santin and 5,7,4'-trihydroxy-3,3'-dimethoxyflavone), and ten sesquiterpenes [1alpha-hydroperoxy-4beta,8alpha,10alpha,13-tetrahydroxyguaia-2-en-12,6alpha-olide, 1alpha-hydroperoxy-4alpha,10alpha-dihydroxyguaia-9alpha-angeloyloxyguaia-2,11(13)-dien-12,6alpha-olide, 3beta,4alpha-dihydroxyguaia-11(13),10(14)-dien-12,6alpha-olide, 1alpha,4alpha,10alpha-trihydroxy-9alpha-angeloyloxyguaia-2,11(13)-dien-12,6alpha-olide, 1beta,2beta-epoxy-3beta,4alpha,10alpha-trihydroxy-guaia-11(13)-en-12,6alpha-olide and 2-oxo-8alpha-hydroxyguaia-1(10),3,11(13)-trien-12,6alpha-olide, ketoplenolide B, alantolactone, 9beta-hydroxyeudesma-4,11(13)-dien-12-oic acid and 9beta-acetoxyeudesma-4,11(13)-dien-12-oic acid]. The structures of the three guaianolides were elucidated by a combination of spectroscopic methods (EIMS, HREIMS, COSY, HMQC, HMBC and NOESY) as 1beta,2beta-epoxy-3beta,4alpha,8beta,10alpha-tetrahydroxyguaia-11(13)-en-12,6alpha-olide (1), 1beta,2beta-epoxy-3beta,4alpha,9alpha,10alpha-tetrahydroxyguaia-11(13)-en-12,6alpha-olide (2) and 1beta,2beta-epoxy-10alpha-hydroperoxy-3beta,4alpha,8beta-trihydroxyguaia-11(13)-en-12,6alpha-olide (3), respectively. Antifungal bioassay of all isolates showed that guaianolides 1, 2, 3, and 1beta,2beta-epoxy-3beta,4alpha,10alpha-trihydroxyguaia-11(13)-en-12,6alpha-olide were inhibitory to the growth of Candida albicans with MICs being 20, 20, 20, and 40 microg/ml, respectively.
Antifungal Agents↗
Molecular characterization of Newcastle disease viruses isolated from recent outbreaks in Taiwan.
A reverse transcription-polymerase chain reaction (RT-PCR) was described which amplified a portion of the F and HN genes of Newcastle disease virus (NDV) isolated from recent outbreaks in Taiwan. The F protein plays an important role in determining the virulence of NDV strains. Sequencing of a region specifying the F protein cleavage site was therefore undertaken and this verified the correlation between deduced amino sequences and pathogenicity. Analysis of the deduced amino acid sequences of the F protein cleavage site showed that all recent Taiwanese isolates in 1999 were velogenic viruses. All the virulent viruses have the amino acid sequence 112RRQKR116 for the C-terminus of the F2 protein and phenylanine (F) at the N-terminus of the F1 protein, residue 117. A phylogenetic tree based on the nucleotide sequences of the F gene revealed that recent Taiwanese NDV isolates responsible for recent outbreaks were classified into two distant genotypes (VI and VII). Genotype VI virus is the first finding in Taiwan and has a highly genetic similarity to European isolates, suggesting that they might have originated from a common ancestor.
Amino Acid Sequence↗