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1.
Rev Sci Instrum ; 94(3): 035106, 2023 Mar 01.
Article in English | MEDLINE | ID: mdl-37012784

ABSTRACT

The compressed ultrafast photography (CUP) can capture non-repetitive time-evolving events at 7 × 1013 fps, which is anticipated to find a diverse range of applications in physics, biomedical imaging, and materials science. The feasibility of diagnosing ultrafast phenomenon of Z-pinch by using the CUP has been analyzed in this article. Specifically, a dual-channel CUP design has been adopted for acquiring high quality reconstructed images and the strategies of identical masks, uncorrelated masks, and complementary masks have been compared. Furthermore, the image of the first channel was rotated by 90° to balance the spatial resolution between the sweep direction and the non-sweep direction. Both five synthetic videos and two simulated Z-pinch videos were chosen as the ground truth to validate this approach. The average peak signal to noise ratio of the reconstruction results is 50.55 dB for the self-emission visible light video and 32.53 dB for the laser shadowgraph video with unrelated masks (rotated channel 1). The simulation results show that the time-space-evolving process of plasma distribution can be well retold, and the phenomenon of plasma instability can be accurately diagnosed by the dual-channel CUP with unrelated masks (rotated channel 1). This study may promote the practical applications of the CUP in the field of accelerator physics.

2.
Rev Sci Instrum ; 93(3): 033702, 2022 Mar 01.
Article in English | MEDLINE | ID: mdl-35365019

ABSTRACT

A high-speed radiation imaging system based on an image converter of liquid scintillator filled capillary arrays has been developed, which is sensitive to x rays, gamma rays, and neutrons. This imaging system has advantages of both high spatial resolution and high sensitivity because increasing the thickness of the image converter only leads to little deterioration on imaging resolution. The capillary arrays have dimensions of 150 mm diameter and 50 mm thickness, with 100 µm diameter of each capillary. The fluorescence decay time of the filled liquid scintillator based on the mixture of p-xylene and 2,5-diphenyloxazole has been evaluated to be ∼3 ns with the single photon method under the gamma ray excitation. The spatial resolution has been experimentally evaluated to be about 1.15 and 0.6 mm, under excitation of x rays and neutrons, respectively. The imaging system has been applied for diagnosing the dynamic x-ray spot generated by the rod pinch. Two frames in single shot with 15 ns temporal resolution and 20 ns inter-frame separation time have been obtained, which show the spatiotemporal distribution of the electrons bombarding the tungsten rod, indicating the ability of this imaging system in diagnosing dynamic radiation objects. In addition, the technique of capillary arrays provides a promising path for applications of advanced liquid scintillators in the field of radiation imaging.

3.
Poult Sci ; 101(4): 101697, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35176705

ABSTRACT

Calcification of bones is the critical process of bone development in birds, which is very important for sustaining the normal biological function of bones. Light is one of the vital factors affecting bone development, but whether light intensity affects bone calcification and the underlying mechanism is still unknown. In this study, we used duck sternum as a model to analyze the calcification process under different light regimes. In addition, the underlying mechanism was also illustrated by integrating metabolomics and transcriptome methods. The experiment lasted from 14 to 51 d of duck age. The control group (LP1) kept light intensity 2 lx during the whole experiment. The two light supplement groups (LP2, LP3) were given light with the intensity of 70 lx at different time (14-29 d for LP2, 14-43 d for LP3). Samples were collected at 52 d of duck age. Sternal calcification analysis showed no significant difference in proportion of area of cartilage matrix and trabecular bone in keel tissue among the 3 groups, but the degree of keel calcification in LP3 was higher than in the other 2 groups. Serum metabolomics showed 32 and 28 differentially accumulated metabolites (DAMs) in the 2 comparison groups, LP1 vs. LP3 and LP1 vs. LP2, respectively. Carboxylic acids and derivatives were the most abundant among the DAMs. Sternal transcriptome analysis showed 231 differentially expressed genes (DEGs), including 177 upregulated genes and 54 downregulated genes in group LP1 vs. LP3, and 22 DEGs in group LP1 vs. LP2. Protein-protein interaction (PPI) network analysis on DEGs between LP1 and LP3 showed that genes BTRC, GLI1, BMP4, and FOS were in the core position of the interaction network, and are also involved in bone development. KEGG pathway analysis of DAMs and DEGs showed that differences in Hedgehog signaling pathway, MAPK signaling pathway, apoptosis, energy metabolism, and amino acid metabolism following light treatment seem likely to have contributed to the observed difference in calcification of duck sternum.


Subject(s)
Ducks , Transcriptome , Animals , Chickens/genetics , Ducks/genetics , Gene Expression Profiling/veterinary , Hedgehog Proteins/genetics , Metabolome , Sternum
4.
Poult Sci ; 100(7): 101208, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34102480

ABSTRACT

To explored the difference of goose fatty liver formation induced-by different types of sugar from the intestinal physiology and the gut microflora, an integrated analysis of intestinal physiology and gut microbiota metagenomes was performed using samples collected from the geese including the normal-feeding geese and the overfed geese which were overfed with maize flour or overfeeding dietary supplementation with 10% sugar (glucose, fructose or sucrose, respectively), respectively. The results showed that the foie gras weight of the fructose group and the sucrose group was heavier (P < 0.05) than other groups. Compared with the control group, the ileum weight was significantly higher (P < 0.01), and the cecum weight was significantly lower in the sugar treatment groups (P < 0.001). Compared with the control group, the ratio of villi height to crypt depth in the fructose group was the highest in jejunum (P < 0.05); the trypsin activity of the ileum was higher in the fructose group and the sucrose group (P < 0.05). At the phylum level, Firmicutes, Proteobacteria and Bacteroidetes were the main intestinal flora of geese; and the abundance of Firmicutes in the jejunum was higher in the sugar treatment groups than that of the maize flour group. At the genus level, the abundance of Lactobacillus in the jejunum was higher (P < 0.05) in the sugar treatment groups than that of the maize flour group. In conclusion, forced-feeding diet supplementation with sugar induced stronger digestion and absorption capacity, increased the abundance of Firmicutes and Bacteroidetes and the abundance of Lactobacillus (especially fructose and sucrose) in the gut. So, the fructose and sucrose had higher induction on hepatic steatosis in goose fatty liver formation.


Subject(s)
Fatty Liver , Gastrointestinal Microbiome , Animals , Chickens , Fatty Liver/veterinary , Geese , Sugars
5.
Poult Sci ; 100(3): 100960, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33652539

ABSTRACT

To have a better understanding of how the "gut-liver axis" mediates the lipid deposition in the liver, a comparison of overfeeding influence on intestine physiology and microbiota between Gang Goose and Tianfu Meat Goose was performed in this study. After force-feeding, compared with Gang Goose, Tianfu Meat Goose had better fat storage capacity in liver (397.94 vs. 166.54 for foie gras weight (g), P < 0.05; 6.37 vs. 2.92% for the ratio of liver to body, P < 0.05; 60.01 vs. 46.64% for fat content, P < 0.05) and the less subcutaneous adipose tissue weight (1240.96 g vs. 1440.46 g, P < 0.05). After force-feeding, the digestion-absorption capacity of Tianfu Meat Goose was higher than that of Gang Goose (5.56 vs. 3.64 and 4.63 vs. 3.68 for the ratio of villus height to crypt depth in duodenum and ileum, respectively, P < 0.05; 1394.96 vs. 782.59 and 1314.76 vs. 766.17 for the invertase activity (U/mg-prot), in duodenum and ileum, respectively, P < 0.05; 6038.36 vs. 3088.29 and 4645.29 vs. 3927.61 for the activity of maltase (U/mg-prot), in duodenum and ileum, respectively, P < 0.05). Force-feeding decreased the gene expression of Escherichia coli in the ileum of Tianfu Meat Goose; force-feeding increased the number of gut microbiota Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction band in Tianfu Meat Goose and decreased the number in Gang Goose. In conclusion, compared with Gang Goose, the lipid deposition in the liver and the intestine digestion-absorption capacity and stability were higher in Tianfu Meat Goose. Thereby, Tianfu Meat Goose is the better breed for foie gras production for prolonged force-feeding; Gang Goose possesses better fat storage capacity in subcutaneous adipose tissue. However, Gang Goose has lower gut stability responding to force-feeding, so Gang Goose is suited to force-feeding in a short time to gain the body weight and subcutaneous fat as an overfed duck for roast duck.


Subject(s)
Feeding Methods , Gastrointestinal Microbiome , Geese , Intestines , Animals , Feeding Methods/veterinary , Gastrointestinal Microbiome/physiology , Intestines/microbiology , Intestines/physiology , Species Specificity
6.
Neoplasma ; 67(2): 354-363, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31986892

ABSTRACT

TNF-α has been confirmed to promote tumor growth in LSCC. PGE2 expression in LSCC tissues was significantly higher than in tumor-adjacent tissues. In the present work, we aimed to discover the combined role of TNF-α and PGE2 in LSCC progression and its potential mechanisms. TNF-α and PGE2 were quantified by ELISA. TRAF2, MMP-9 and GRK2 expressions were detected by immunohistochemistry and western blot. UM-SCC-11A cell proliferation was tested by CCK-8, and cell migration and invasion were determined by transwell assay. GRK2/TRAF2 interaction was tested by Co-IP. The results showed that TNF-α, PGE2, TRAF2, MMP-9 and GRK2 expressions were significantly higher in tumor tissues than in tumor-adjacent tissues. Higher expressions of TRAF2, MMP-9 and GRK2 were associated with poorer prognosis of LSCC. Combined TNF-α with PGE2 promoted UM-SCC-11A cell proliferation, migration and invasion. The interactions of TRAF2 and GRK2, as well as MMP-9 expression, were upregulated in response to TNF-α and PGE2 co-stimulation. In conclusion, we found crosstalk between PGE2 and TNF-α signaling pathways, and the interaction between GRK2 and TRAF2 led to the activation of TNF-α-TRAF2-MMP-9 signaling and resulted in the progression of LSCC.


Subject(s)
Carcinoma, Squamous Cell/pathology , Dinoprostone/metabolism , G-Protein-Coupled Receptor Kinase 2/metabolism , Laryngeal Neoplasms/pathology , TNF Receptor-Associated Factor 2/metabolism , Tumor Necrosis Factor-alpha/metabolism , Cell Line, Tumor , Cell Proliferation , Humans , Matrix Metalloproteinase 9/metabolism , Signal Transduction
7.
Genet Mol Res ; 15(3)2016 Jul 25.
Article in English | MEDLINE | ID: mdl-27525855

ABSTRACT

PI3K-Akt-mTOR signaling pathway is associated with endoplasmic reticulum (ER) stress. However, it is not clear how this signaling pathway affects the ER stress. The present study aimed to determine whether the PI3K-Akt-mTOR signaling pathway regulates tunicamycin (TM)-induced increases in mRNA levels of genes involved in the ER stress, to help elucidate the mechanism by which this pathway affects the ER stress in primary goose hepatocytes. Primary hepatocytes were isolated from geese and cultured in vitro. After 12 h in a serum-free medium, the hepatocytes were incubated for 24 h in a medium with either no addition (control) or with supplementation of TM or TM together with PI3K-Akt-mTOR signaling pathway inhibitors (LY294002, rapamycin, NVP-BEZ235). Thereafter, the expression levels of genes involved in the ER stress (BIP, EIF2a, ATF6, and XBP1) were assessed. The results indicated that the mRNA level of BIP was up-regulated in 0.2, 2, and 20 µM TM treatment group (P < 0.05), whereas the mRNA levels of EIF2a, ATF6, and XBP1 were up-regulated in the 2 µM TM treatment group (P < 0.05). However, the TM mediated induction of mRNA levels of genes involved in the ER stress (BIP, EIF2a, ATF6, and XBP1) was down-regulated after the treatment with PI3K-Akt-mTOR pathway inhibitors (LY294002, NVP-BEZ235, and rapamycin). Therefore, our results strongly suggest that the PI3K-Akt-mTOR signaling pathway might be involved in the down-regulation of the TM-induced ER stress in primary goose hepatocytes.


Subject(s)
Endoplasmic Reticulum Stress/genetics , Phosphoinositide-3 Kinase Inhibitors , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , TOR Serine-Threonine Kinases/antagonists & inhibitors , Tunicamycin/pharmacology , Animals , Apoptosis/drug effects , Apoptosis/genetics , Cell Proliferation/drug effects , Cell Proliferation/genetics , Cells, Cultured , Endoplasmic Reticulum Stress/drug effects , Geese , Gene Expression Regulation/drug effects , Hepatocytes/drug effects , Hepatocytes/metabolism , Hepatocytes/physiology , Phosphatidylinositol 3-Kinases/genetics , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Signal Transduction , TOR Serine-Threonine Kinases/genetics , TOR Serine-Threonine Kinases/metabolism , Unfolded Protein Response
8.
Animal ; 10(8): 1319-27, 2016 Aug.
Article in English | MEDLINE | ID: mdl-26956906

ABSTRACT

UNLABELLED: Phosphatidylinositol-3 kinases (PI3K)-Protein kinase B (Akt)-mammalian target of rapamycin (mTOR) pathway plays an important role in the synthesis and secretion of triacylglycerol. However, the mechanism of PI3K-Akt-mTOR pathway in regulating lipid metabolism of goose liver was poorly understood. The purpose of this study was to determine how PI3K-Akt-mTOR pathway regulating lipid metabolic homeostasis in goose hepatocytes. Goose primary hepatocytes were treated with different PI3K-Akt-mTOR signal inhibitors (LY294002, rapamycin and NVP-BEZ235) for 24 h. The results showed that these inhibitors evidently inhibited PI3K-Akt-mTOR downstream signaling. Meanwhile, these PI3K-Akt-mTOR inhibitors reduced intracellular lipid accumulation, decreased the mRNA expression and protein content of genes involved in the de novo fatty acid synthesis, while increased the transcriptional and protein level of key factors involved in fatty acid oxidation and very low density lipoprotein (VLDL) assembly and secretion. CONCLUSION: These findings suggested that the reduction of lipids accumulation induced-by inhibiting PI3K-Akt-mTOR pathway was closely linked to the decrease of lipogenesis, the increase of fatty acids oxidation, and the increase of VLDL assembly and secretion in goose hepatocytes.


Subject(s)
Geese/metabolism , Lipid Metabolism/drug effects , Phosphoinositide-3 Kinase Inhibitors , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Signal Transduction/drug effects , TOR Serine-Threonine Kinases/antagonists & inhibitors , Animals , Hepatocytes/drug effects , Homeostasis/drug effects , Liver/drug effects , Liver/metabolism
9.
Genet Mol Res ; 12(3): 4046-59, 2013 Sep 27.
Article in English | MEDLINE | ID: mdl-24089094

ABSTRACT

The amphidromous goby Sicyopterus japonicus is distributed throughout southern Taiwan and Japan. Larvae of this freshwater fish go through a long marine stage. This migratory mode influences population genetic structure. We examined the genetic diversity, population differentiation, and demographic history of S. japonicus based on the mitochondrial DNA control region. We identified 102 haplotypes from 107 S. japonicus individuals from 22 populations collected from Taiwan and Islet Lanyu. High mean haplotype diversity (h = 0.999) versus low nucleotide diversity (θπ = 0.008) was detected across populations. There was low correspondence between clusters identified in the neighbor-joining tree and geographical region, as also indicated by AMOVA and pairwise F(ST) estimates. Both mismatch distribution analysis and Tajima's D test indicated that S. japonicus likely experienced a demographic expansion. Using a Bayesian skyline plot approach, we estimated the time of onset of the expansion of S. japonicus at 135 kyr (during the Pleistocene) and the time of stable effective population size at approximately 2.5 kyr (last glacial maximum). Based on these results, we suggest 1) a panmictic population at the oceanic planktonic larval stage, mediated by the Kuroshio current; 2) a long planktonic marine stage and long period of dispersal, which may have permitted efficient tracking of environmental shifts during the Pleistocene; and 3) a stable, constant population size ever since the last glacial maximum.


Subject(s)
DNA, Mitochondrial/genetics , Perciformes/classification , Perciformes/genetics , Animals , Genetic Variation , Haplotypes , Phylogeny , Phylogeography , Population Density , Sequence Analysis, DNA , Taiwan
10.
Mol Cell Biochem ; 374(1-2): 163-72, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23180245

ABSTRACT

To investigate how cholesterol induces hepatocytic steatosis, we investigated the effect of cholesterol on hepatic lipogenesis and the assembly and secretion of very-low-density lipoprotein-triglycerides (VLDL-TGs) in goose primary hepatocytes. We found that cholesterol at 20 µg/ml increased the concentrations of extracellular VLDL, intracellular cholesterol, and intracellular TGs, while cholesterol at 30 µg/ml had a reduced effect (p < 0.05). Additionally, cholesterol at 20 µg/ml, but not at 10 or 30 µg/ml, increased the extracellular TG concentration. Cholesterol increased the fatty acid synthase (FAS) enzyme activity in a dose-dependent manner. Incubation with cholesterol increased the mRNA level of genes involved in lipogenesis, including sterol regulatory element-binding proteins (SREBPs), FAS, acetyl-CoA carboxylase-α (ACCα), and liver X receptors. The mRNA level of the acyl-CoA: diacylglycerol acyltransferase 1 (DGAT1) gene changed in response to cholesterol treatment in a dose-dependent manner. Similar to the regulation of extracellular VLDL and intracellular TG accumulation, the mRNA levels of the microsomal triglyceride transfer protein, forkhead box O1, and DGAT2 increased with treatment with 10 or 20 µg/ml of cholesterol, but decreased with treatment with 30 µg/ml of cholesterol (p < 0.05). Cholesterol had no evident effect on the mRNA level of the apolipoprotein B gene. Incubation with cholesterol at 20 and 30 µg/ml increased the nuclear SREBP-1 protein level (p < 0.05) and the binding affinity of the nuclear SREBP-1 to ACCα SRE probes. In conclusion, cholesterol not only activates the transcription of genes involved in fatty acid synthesis and TG accumulation, but also activates the transcription of genes involved in the assembly and secretion of VLDL-TG in goose primary hepatocytes.


Subject(s)
Cholesterol/pharmacology , Hepatocytes/metabolism , Lipogenesis/drug effects , Lipoproteins, VLDL/metabolism , Triglycerides/metabolism , Acetyl-CoA Carboxylase/biosynthesis , Animals , Cells, Cultured , Cholesterol/metabolism , Diacylglycerol O-Acyltransferase/genetics , Fatty Acid Synthases/metabolism , Fatty Liver , Forkhead Transcription Factors/genetics , Geese , Lipid Metabolism/drug effects , Lipid Metabolism/genetics , Lipogenesis/genetics , Liver X Receptors , Orphan Nuclear Receptors/biosynthesis , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sterol Regulatory Element Binding Protein 1/genetics , Sterol Regulatory Element Binding Protein 1/metabolism
11.
J Appl Physiol (1985) ; 111(6): 1789-97, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21885804

ABSTRACT

In ovo administration of IGF-1 to poultry eggs has effective roles on post hatching muscle development. However, the secondary muscle development stages at the late embryo development stage are important for muscle fiber formation and differentiation. To investigate the roles of in ovo administration of IGF-1 on duck secondary muscle development, we injected rhIGF-1 into duck eggs in hatching at day 12. After administration on days 18, 21, 24, and 27 in hatching (E18d, E21d, E24d, and E27d, respectively), muscle samples were isolated, and the muscle tissue weight, muscle fiber parameters, and myoblast proliferation rate in leg and breast muscle were analyzed. Additionally, the expression levels of the transcription factors MyoG and MRF4 were detected using qPCR. Results show that embryo body weight and muscle fiber parameters, including muscle fiber diameter (MFD) and the number of myofibers per unit area, are upregulated in IGF-1-treated groups. Moreover, the transcription factors MyoG and MRF4 are expressed at higher levels in the experimental groups compared with the control groups. These results suggest that in ovo administration of IGF-1 to poultry eggs can mediate the expression of MyoG and MRF4, induce myoblast proliferation, and finally influence muscle development during the secondary muscle development stages.


Subject(s)
Ducks/embryology , Ducks/genetics , Insulin-Like Growth Factor I/administration & dosage , Myogenic Regulatory Factors/genetics , Animals , Base Sequence , Cell Proliferation/drug effects , Female , Gene Expression Regulation, Developmental/drug effects , Humans , Muscle Development/drug effects , Muscles/drug effects , Muscles/embryology , Myoblasts/drug effects , Myogenin/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Recombinant Proteins/administration & dosage , Up-Regulation/drug effects
12.
Poult Sci ; 90(2): 402-9, 2011 Feb.
Article in English | MEDLINE | ID: mdl-21248338

ABSTRACT

In this study, we investigated the role of liver X receptor (LXR) activation in hepatic assembly and in the secretion of very low density lipoprotein-triglycerides in goose primary hepatocytes. Goose primary hepatocytes were isolated and treated with the LXR agonist T0901317. Total triglyceride accumulation, intracellular and extracellular triglyceride concentrations, extracellular very low density lipoprotein concentration, and gene expression levels of LXRα, microsomal triglyceride transfer protein, acyl coenzyme A:diacylglycerol acyltransferase (DGAT) 1, and DGAT2 were measured in primary hepatocytes. We found a dose-dependent upregulation of total and intracellular TG accumulation when using 0, 0.01, 0.1, 1, and 10 µM T0901317, but the extracellular triglyceride and very low density lipoprotein concentrations were dose dependent only when the T0901317 concentration was below 1 µM; as compared with 1 µM T0901317, 10 µM T0901317 had an inhibiting effect (P < 0.05). The mRNA levels of all the detected genes increased in the presence of T0901317. The change in LXRα and DGAT1 was dose dependent, and the mRNA levels of microsomal triglyceride transfer protein and DGAT2 increased with a T0901317 concentration up to 1 µM, but decreased when treated with 10 µM T0901317 (P < 0.05). In conclusion, the secretion of very low density lipoprotein plays a role in pharmacologically activating the LXR-induced development of hepatocellular steatosis in geese.


Subject(s)
Geese/metabolism , Gene Expression Regulation/physiology , Hepatocytes/metabolism , Lipoproteins, VLDL/metabolism , Orphan Nuclear Receptors/metabolism , RNA, Messenger/metabolism , Animals , Cells, Cultured , Gene Expression Regulation/drug effects , Hepatocytes/drug effects , Hydrocarbons, Fluorinated/pharmacology , Liver X Receptors , Orphan Nuclear Receptors/genetics , RNA, Messenger/genetics , Sulfonamides/pharmacology
13.
Anal Chem ; 77(1): 259-65, 2005 Jan 01.
Article in English | MEDLINE | ID: mdl-15623304

ABSTRACT

Carboxylated/oxidized diamond nanoparticles (nominal size 100 nm) exhibit exceptionally high affinity for proteins through both hydrophilic and hydrophobic forces. The affinity is so high that proteins in dilute solution can be easily captured by diamonds, simply separated by centrifugation, and directly analyzed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). No preseparation of the adsorbed molecules from diamonds is required for the mass spectrometric analysis. Compared to conventional MALDI-TOF-MS, an enhancement in detection sensitivity by more than 2 orders of magnitude is achieved for dilute solution containing cytochrome c, myoglobin, and albumin because of preconcentration of the probed molecules. The lowest concentration detectable is 100 pM for a 1-mL solution. Aside from the enhanced sensitivity, the overall performance of this technique does not show any sign of deterioration for highly contaminated protein solutions, and furthermore, no significant peak broadening and band shift were observed in the mass spectra. The promise of this new method for clinical proteomics research is demonstrated with an application to human blood serum.


Subject(s)
Nanoparticles , Proteins/analysis , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Adsorption , Blood Proteins/analysis , Diamond , Humans
14.
J Colloid Interface Sci ; 274(2): 515-25, 2004 Jun 15.
Article in English | MEDLINE | ID: mdl-15144824

ABSTRACT

The equilibrium structure and shear response of model polymer-clay nanocomposite gels are measured using X-ray scattering, light scattering, optical microscopy, and rheometry. The suspensions form physical gels via the "bridging" of neighboring colloidal clay platelets by the polymer, with reversible adsorption of polymer segments onto the clay surface providing a short-range attractive force. As the flow disrupts this transient network, coupling between composition and stress leads to the formation of a macroscopic domain pattern, while the clay platelets orient with their surface normal parallel to the direction of vorticity. We discuss the shear-induced structure, steady-shear rheology, and oscillatory-shear response of these dynamic networks, and we offer a physical explanation for the mesoscale shear response. In contrast to flow-induced "banding" transitions, no stress plateau is observed in the region where macroscopic phase separation occurs. The observed platelet orientation is different from that reported for polymer-melt clay nanocomposites, which we attribute to effects associated with macroscopic phase separation under shear flow.

15.
Ann Acad Med Singap ; 32(5): 665-9, 2003 Sep.
Article in English | MEDLINE | ID: mdl-14626799

ABSTRACT

INTRODUCTION: The objectives of this review were to document the surgico-pathological characteristics of surgically resected FIGO stage 1B2 cervical carcinoma and to review our overall experience with this disease. MATERIALS AND METHODS: This is a retrospective review of 35 patients diagnosed and treated from September 1990 to November 2001. RESULTS: The median age was 42 years and the mean tumour diameter was 5.1 cm. Majority were squamous cell carcinomas (65.7%), 28.6% were adenocarcinomas and 5.7% were adeno-squamous carcinomas. The primary treatment comprised radical surgery in 77.1%, radiotherapy in 20% and neoadjuvant chemotherapy followed by radical surgery and adjuvant radiotherapy in 2.9%. Significant surgico-pathological features noted were deep stromal invasion (66.7%), lympho-vascular space invasion (55.6%), parametrial involvement (22.2%), positive margins (3.7%) and pelvic node metastases (33.3%). Postoperative radiation was given to 92.6% of the patients who underwent primary surgery, of whom 29% received concurrent chemotherapy. Radiation toxicity was mild with no grade 3 or 4 toxicity documented. For the patients who had surgery, the recurRence rate was 14.8% (11.1% pelvic and 3.7% distant) and the survival rate was 88.9%. For those who had primary radiation, the rate of persistent disease was 28.6%, the distant recurrence rate was 28.6% and the survival rate was 57.1%. CONCLUSION: FIGO stage 1B2 cervical carcinomas are associated with significant rates of adverse surgico-pathological features. The ideal primary treatment is yet to be established and should be determined by prospective randomised trials.


Subject(s)
Carcinoma, Squamous Cell/epidemiology , Carcinoma, Squamous Cell/pathology , Neoplasm Recurrence, Local/pathology , Uterine Cervical Neoplasms/epidemiology , Uterine Cervical Neoplasms/pathology , Adult , Age Distribution , Aged , Biopsy, Needle , Carcinoma, Squamous Cell/therapy , Cohort Studies , Combined Modality Therapy , Female , Humans , Hysterectomy/methods , Immunohistochemistry , Incidence , Middle Aged , Neoplasm Recurrence, Local/epidemiology , Neoplasm Recurrence, Local/therapy , Neoplasm Staging , Retrospective Studies , Risk Assessment , Singapore/epidemiology , Survival Analysis , Treatment Outcome , Uterine Cervical Neoplasms/therapy
16.
Eur J Gynaecol Oncol ; 24(1): 85-8, 2003.
Article in English | MEDLINE | ID: mdl-12691327

ABSTRACT

BACKGROUND: A rare case of metastatic ovarian carcinoma arising from intrahepatic cholangiocarcinoma is reported and the literature reviewed. CASE: A 49-year-old woman presented with ascites and a left pelvic mass. Optimal debulking surgery was carried out including a segmental resection of segment 5/6 of the liver. Histopathology confirmed an intrahepatic cholangiocarcinoma metastatic to the ovaries and omentum. CONCLUSION: Distinguishing a metastatic tumor from a primary ovarian tumoris critical for appropriate management. A high index of suspicion intraoperatively and subsequent expert pathological review are essential in making the correct diagnosis.


Subject(s)
Bile Duct Neoplasms/pathology , Bile Ducts, Intrahepatic/pathology , Cholangiocarcinoma/secondary , Ovarian Neoplasms/secondary , Abdominal Pain/physiopathology , Bile Duct Neoplasms/surgery , Biopsy, Needle , Cholangiocarcinoma/surgery , Female , Follow-Up Studies , Hepatectomy/methods , Humans , Immunohistochemistry , Laparotomy/methods , Middle Aged , Neoplasm Staging , Ovarian Neoplasms/surgery , Ovariectomy/methods , Rare Diseases , Risk Assessment , Treatment Outcome
17.
Phys Rev E Stat Nonlin Soft Matter Phys ; 67(6 Pt 1): 061801, 2003 Jun.
Article in English | MEDLINE | ID: mdl-16241248

ABSTRACT

The existence of a transient period during the surface enrichment of a binary polymer blend by one of its components has been suggested by previous theoretical and experimental studies as well as computer simulations. Taking advantage of the high depth resolution of neutron reflectivity and the slow dynamics of polymers near their glass transition, we investigate this early-stage surface compositional enrichment in a phase separating polymer blend for the first time. Two stages of surface enrichment layer growth are observed. A rapid local surface enrichment at the chain segmental level occurs first, followed by a slower growth of a diffuse layer having a scale on the order of the bulk correlation length and the radius of gyration of the surface enriching polymer chains.

18.
Anal Chem ; 74(17): 4434-40, 2002 Sep 01.
Article in English | MEDLINE | ID: mdl-12236352

ABSTRACT

Charged polystyrene nanoparticles are generated by matrix-assisted laser desorption/ionization (MALDI) and detected by laser-induced fluorescence (LIF) in a quadrupole ion trap. Employing the LIF technique, observations of individual fluorescent nanospheres (27 nm in diameter and containing 180 fluorescein dye equivalents) have been achieved with an average signal-to-noise ratio of approximately 10. With the trap operating at a frequency around 5 kHz, charge state analysis of the particles reveals that the number of charges carried by the spheres is between 1 and 10. It suggests a mass-to-charge ratio (m/z) in the range of 10(5)-10(6) for the MALDI-generated particles. To effectively trap such large particles (m > 5 MDa), damping of the particles' motions by using approximately 50 mTorr He buffer gas is absolutely required. Similar findings are obtained for particles with a nominal size of 1 microm in diameter, demonstrating that production of charged particles with a molecular mass as high as 10(12) Da is possible using the MALDI technique.


Subject(s)
Molecular Probe Techniques , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Fluorescent Dyes , Fluorometry , Microspheres , Molecular Weight , Nanotechnology/methods , Particle Size , Polystyrenes
19.
Appl Opt ; 40(31): 5770-7, 2001 Nov 01.
Article in English | MEDLINE | ID: mdl-18364868

ABSTRACT

Lateral light-distribution images of biologic tissues were used to study the tissues' optical characteristics. Monte Carlo simulation with the same conditions was performed to simulate the light distribution for comparison. Simulation results showed that the lateral light distribution was similar to the internal light distribution in biologic tissue. The direction of muscle fibers and the temperature both affect the near-field light distribution in tissue. The lateral view distribution can be both measured and simulated to study photon migration in tissue. It can also be used to estimate or verify the optical coefficients of tissue.

20.
J Mol Biol ; 301(2): 525-36, 2000 Aug 11.
Article in English | MEDLINE | ID: mdl-10926525

ABSTRACT

In order to understand the changes in protein dynamics that occur in the final stages of protein folding, we have used neutron scattering to probe the differences between a protein in its folded state and the molten globule states. The internal dynamics of bovine alpha-lactalbumin (BLA) and its molten globules (MBLA) have been examined using incoherent, quasielastic neutron scattering (IQNS). The IQNS results show length scale dependent, pico-second dynamics changes on length scales from 3.3 to 60 A studied. On shorter-length scales, the non-exchangeable protons undergo jump motions over potential barriers, as those involved in side-chain rotamer changes. The mean potential barrier to local jump motions is higher in BLA than in MBLA, as might be expected. On longer length scales, the protons undergo spatially restricted diffusive motions with the diffusive motions being more restricted in BLA than in MBLA. Both BLA and MBLA have similar mean square amplitudes of high frequency motions comparable to the chemical bond vibrational motions. Bond vibrational motions thus do not change significantly upon folding. Interestingly, the quasielastic scattering intensities show pronounced maxima for both BLA and MBLA, suggesting that "clusters" of atoms are moving collectively within the proteins on picosecond time scales. The correlation length, or "the cluster size", of such atom clusters moving collectively is dramatically reduced in the molten globules with the correlation length being 6.9 A in MBLA shorter than that of 18 A in BLA. Such collective motions may be important for the stability of the folded state, and may influence the protein folding pathways from the molten globules.


Subject(s)
Lactalbumin/chemistry , Protein Folding , Animals , Calcium/chemistry , Cattle , Models, Molecular , Neutrons , Protein Structure, Secondary , Scattering, Radiation
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