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ABSTRACT: The aim of this study was to develop an antiGPC3-ultrasuperparamagnetic iron oxide (USPIO) probe for early detection of hepatocellular carcinoma.
GPC3 and AFP receptors were selected as biomarkers and conjugated with USPIO nanoparticles coated by dextran with carboxylate groups to synthesize antiGPC3-USPIO and antiAFP-USPIO probes. HepG2 cells (a human hepatocellular carcinoma cell model with high expression of GPC3) were used along with SMMC-7721 cells (a hepatocellular carcinoma cell model with no expression of GPC3), HeLa cells (a cervical cancer model), and HL-7702 (normal hepatocytes) which were used as controls. After incubation with the probes, the iron content in the cells was calculated, USPIO nanoparticles in cells were observed using transmission electron microscopy, and T1 and T2 relaxation times were measured with a 1.5 T magnetic resonance scanner.
AntiGPC3-USPIO probes with a mean hydrodynamic diameter of 47 nm showed good biological compatibility. Transmission electron microscopic images indicated that the amount of USPIO nanoparticles taken up was significantly higher in HepG2 cells incubated with antiGPC3-USPIO than that in HepG2 cells incubated with antiAFP-USPIO or USPIO nanoparticles and that in the SMMC-7721 or HeLa cells incubated with antiGPC3-USPIO probes, antiAFP-USPIO probes, or USPIO nanoparticles. The higher the concentration and the longer the incubation time, the greater the number of USPIO nanoparticles found in the cells. No USPIO nanoparticles were found in the HL-7702 cells. All of the HepG2, SMMC-7721, and HeLa cells incubated with antiGPC3-USPIO, antiAFP-USPIO, or USPIO nanoparticles were able to shorten the T1 and T2 values in agar solution, especially the T2 images of HepG2 cells incubated with antiGPC3-USPIO probes.
AntiGPC3-USPIO probes can be utilized as a specific magnetic resonance targeting contrast agent for early detection of hepatocellular carcinoma. Using a 1.5 T magnetic resonance scanner, the optimal time for imaging HepG2 cells was around 2-4 hours after incubation with antiGPC3-USPIO probes.
International Journal of Nanomedicine 01/2012; 7:4593-611. · 3.13 Impact Factor
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ABSTRACT: This meta-analysis evaluates the diagnostic accuracy of diffusion-weighted MR imaging with ADC values for differentiation between malignant and benign hepatic focal lesions. From retrieved articles, we selected 7 sets of data in 6 articles, which met all the included criteria, for meta-analysis. The pooled sensitivity and specificity were 86% (95% CI, 0.83-0.90) and 84% (95% CI, 0.78-0.88), respectively. However, notable heterogeneity between studies was noted and no covariate evaluated can explain the cause. Only b factor correlated with the mean ADC values of malignant and benign hepatic tumors. In conclusion, ADC value was useful for differentiation between malignant and benign hepatic focal lesions. But, significant heterogeneity between studies underlines the need for further efforts to optimize standardization and reproducibility of the utilized techniques and methods.
European journal of radiology 02/2011; 81(3):484-90. · 2.65 Impact Factor
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ABSTRACT: (18)F-FDG-positron emission tomography-computerized tomography ((18)F-FDG-PET/CT) scan is an important imaging tool which may provide both functional and anatomical information in a single diagnostic test. It has the potential to be a valuable tool in the noninvasive evaluation and monitoring of pediatric tumors including the metastases because (18)fluorodeoxyglucose ((18)F-FDG) is a glucose analogue that concentrates in areas of active metabolic activity. This review provides an update on functional and metabolic imaging approaches for assessment and management of the body tumor and metastases in pediatrics using a combined whole body (18)F-FDG-PET/CT scanners. We discuss the benefits include improved pediatric patients' outcome facilitated by staging and monitoring of disease and better treatment planning. It is worth to concern the preparation of children undergoing PET studies and radiation dosimetry and its implications for family and caregivers. It is important to consider the normal distribution of (18)FDG in children, common variations of the normal distribution. We show some of our cases that most tumors in children accumulate and retain FDG, allowing high-quality images of their distribution and pathophysiology either at the primary site as well as in the areas of metastatic disease.
European journal of radiology 09/2010; 75(3):329-35. · 2.65 Impact Factor
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ABSTRACT: Most of functional magnetic resonance imaging (fMRI) experiments have been performed on horizontal bore magnets. Here, we present practical aspects of fMRI based on single-shot, spin-echo echo-planar imaging (EPI) using a widely available, cost effective 89 mm bore vertical 11.7 T microimager. It was demonstrated that reproducible, high-quality fMRI data can be obtained from alpha-chloralose anesthetized adult rat brain. Both coronal and the more extended horizontal EPI images were acquired to measure blood oxygenation level dependent (BOLD) responses to electrical stimulation of fore- and hindpaws. The BOLD patterns observed match the known representations of fore- and hindpaws in the somatosensory cortex in rats. Preliminary results on BOLD signal enhancement using aminophylline are also presented.
Journal of Neuroscience Methods 04/2006; 151(2):268-75. · 1.98 Impact Factor
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ABSTRACT: A single-shot, proton-localized, polarization transfer (13)C spectroscopic method was proposed and implemented on a 4.7 T scanner for studying rhesus monkey brains. The polarization transfer sequence was mostly adiabatic, minimizing signal loss due to B(1) inhomogeneity. RF pulses in polarization transfer were also used for voxel selection of protons with gradient fields. The transferred (13)C magnetization was refocused by additional refocusing adiabatic pulses. With the intravenous infusion of D-[1-(13)C]glucose solution, (13)C NMR spectra from a 30 mL voxel were acquired for the resonances of C1 of glucose, C2,3,4 of glutamate and glutamine. The time-resolved turnover of glutamate, glutamine and aspartate from intravenously infused D-[1-(13)C]glucose at a temporal resolution of 12 min was demonstrated with excellent spectral resolution and signal-to-noise ratio. Typically, the half-height linewidth of the decoupled (13)C peaks was approximately 4 Hz. Data obtained with infusion of sodium [2-(13)C]acetate using the proposed polarization transfer method and data from the carboxylic carbon region using non-localized acquisition are also presented.
NMR in Biomedicine 01/2006; 18(8):560-9. · 3.21 Impact Factor
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ABSTRACT: Vigabatrin and gabaculine, both highly specific inhibitors of GABA (gamma-aminobutyric acid) transaminase, cause significant elevation of endogenous GABA levels in brain. The time course of GABA concentration after acute GABA transaminase inhibition was measured quantitatively in the alpha-chloralose-anesthetized rat brain using in vivo selective homonuclear polarization transfer spectroscopy. The blood oxygenation level-dependent (BOLD) effect in functional magnetic resonance imaging (fMRI) has been considered to be coupled tightly to neuronal activation via the metabolic demand of associated glutamate transport. Correlated with the rise in endogenous GABA level after vigabatrin or gabaculine treatment, the intensity of BOLD-weighted fMRI signals in rat somatosensory cortex during forepaw stimulation was found to be reduced significantly. These results are consistent with previous findings that inhibition of GABA transaminase leads to augmented GABA release and potentiation of GABAergic inhibition.
Journal of Neuroscience Research 03/2005; 79(3):383-91. · 2.74 Impact Factor
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ABSTRACT: Matrix metalloproteinases are important biological effectors of tissue remodelling. Increased MMP expression occurs during injury, inflammation, cellular transformation, and oxidative stress. Oxidative stress in the lens, a causal factor in cataractogenesis, has been shown to induce MMP secretion. The objective of this study was to assess the expression of MMPs and their regulators in an oxidative stress model of cataract, where epithelial cell death and cortical fibre cell swelling occurs in rat lenses after exposure to riboflavin, oxygen, and light. Two time points (4 and 7 hr of exposure) were chosen in order to compare transparent lenses with partially opaque lenses. MMP activity, protein, and mRNA levels were measured. The results show that MMP-2, MMP-9, MT1-MMP, and MT3-MMP are down-regulated by oxidative stress and that the down-regulation is most likely due to reduced gene transcription. In contrast, genes for catalase, glutathione peroxidase, and GAPDH are essentially unaffected, while beta-actin mRNA and protein levels are markedly increased at both time points. The down-regulation of MMPs occurs in lenses still seemingly transparent after 4 hr of exposure, indicating that reduced MMP activity is a relatively early response to the oxidative stress. Moreover, in our model system, MMP inhibition, not induction, is associated with cataractogenesis.
Experimental Eye Research 01/2005; 79(6):839-46. · 3.26 Impact Factor
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ABSTRACT: A novel single-shot in vivo spectral editing method is proposed in which the signal to be detected, is regenerated anew from the thermal equilibrium magnetization of a source to which it is J-coupled. The thermal equilibrium magnetization of the signal to be detected together with those of overlapping signals are suppressed by single-shot gradient dephasing prior to the signal regeneration process. Application of this new strategy to in vivo GABA editing using selective homonuclear polarization transfer allows complete suppression of overlapping creatine and glutathione while detecting the GABA-4 methylene resonance at 3.02 ppm with an editing yield similar to that of conventional editing methods. The NAA methyl group at 2.02 ppm was simultaneously detected and can be used as an internal navigator echo for correcting the zero order phase and frequency shifts and as an internal reference for concentration. This new method has been demonstrated for robust in vivo GABA editing in the rat brain and for study of GABA synthesis after acute vigabatrin administration.
Journal of Magnetic Resonance 11/2004; 170(2):290-8. · 2.14 Impact Factor
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ABSTRACT: To propose new frequency offset corrected inversion (FOCI) pulses with significantly reduced radiofrequency (RF) power deposition for spin echo imaging by incorporating the variable-rate selective excitation (VERSE) schemes into the pulse design.
Two schemes are proposed to design the new FOCI pulses with dramatically reduced peak RF power requirements. In scheme A, the time-dilation function is derived from a predefined adiabaticity factor modulation function. In scheme B, the time-dilation function is predefined, while the adiabaticity factor is conserved.
The new FOCI pulses are shown to be able to operate at reduced specific absorption rate (SAR), specifically at the same peak RF power as that of a five- or seven-lobe sinc inversion pulse of the same duration. Using the new FOCI pulse, significant gain in sensitivity was observed in in vivo spin-echo echo-planar imaging, which was attributed to the improved refocusing slice profile.
The new FOCI pulses can replace the 180 degrees five- or seven-lobe sinc pulses in spin-echo imaging with the same peak RF power requirement and significantly improved slice profile.
Journal of Magnetic Resonance Imaging 10/2004; 20(3):531-7. · 2.70 Impact Factor
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ABSTRACT: In vivo B(0) inhomogeneity in the rat brain at 11.7 Tesla was measured and decomposed up to the fourth-order spherical harmonic terms using an automatic slice shimming routine derived from the FLATNESS method. In vivo shimming of horizontal slices showed that significant improvement in the T(2)*-weighted echo-planar imaging was achieved after correction of all first-, second- and third-order in-slice shims. For localized proton spectroscopy, reproducible, high quality data were obtained after correcting all first- and second-order shims. The measured high-order in vivo B(0) inhomogeneity in terms of spherical harmonic terms should provide a useful guide for designing shims to meet in vivo requirements.
Magnetic Resonance Imaging 08/2004; 22(6):835-42. · 1.99 Impact Factor
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ABSTRACT: Transforming growth factor-beta2 (TGF-beta2) induces anterior subcapsular cataracts, with a marked increase in cytoskeletal and extracellular matrix proteins, such as alpha-smooth muscle actin (alphaSMA). It has been shown that 17beta-estradiol (E2) can prevent TGF-beta2-induced cataracts in lenses from ovariectomized female rats. The purpose of the current study was to extend this finding by testing whether E2 can prevent TGF-beta2-induced cataracts and inhibit the induction of alphaSMA gene expression in normal male and normal, non-ovariectomized female rats.Sex-specific differences were observed in 17-week-old rat lenses incubated in 0.15 ng ml(-1) TGF-beta2 and in 10(-8)M E2 plus TGF-beta2. TGF-beta2 induced approximately twice as many anterior subcapsular plaques and 1.5 times the level of alphaSMA transcripts in male lenses compared to female lenses. Notably, E2 inhibited plaque formation and the induction of alphaSMA transcripts in female rat lenses but not in male rat lenses. E2 also inhibited the induction of alphaSMA in TGF-beta2-incubated lenses from ovariectomized female rats.E2 prevented lens opacification and the induction of alphaSMA gene expression in female, but not male, lenses. This sex-specific difference may have implications for studies on the therapeutic use of estradiol for treatment of secondary cataract.
Experimental Eye Research 02/2004; 78(1):67-74. · 3.26 Impact Factor
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ABSTRACT: For face recognition, traditional appearance-based methods represented raw face images as vectors and employed dimensionality reduction techniques to capture the structure of the face space. The tensor subspace analysis (TSA) algorithm uses second order tensor to represent face images and assumes the face images reside on or close to a submanifold embedded in the tensor space. The effectiveness of TSA has been demonstrated. However, TSA is time consuming since it needs to solve a series of eigen-problems. In this paper we propose a novel efficient appearance-based face recognition method called tensor subspace regression (TSR). Like TSA, we also represent face images in tensor spaces. The difference is that we cast the facial subspace learning (i.e. dimensionality reduction) problem in a regression framework which avoids the high computational eigen-step. We show the efficiency of our algorithm by analytically and empirically comparing it with TSA. Finally, experimental results on three popular facial databases show that our algorithm can also achieve acceptable performance for face classification and clustering.
Neurocomputing.
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ABSTRACT: Most of functional magnetic resonance imaging (fMRI) experiments have been performed on horizontal bore magnets. Here, we present practical aspects of fMRI based on single-shot, spin-echo echo-planar imaging (EPI) using a widely available, cost effective 89 mm bore vertical 11.7 T microimager. It was demonstrated that reproducible, high-quality fMRI data can be obtained from α-chloralose anesthetized adult rat brain. Both coronal and the more extended horizontal EPI images were acquired to measure blood oxygenation level dependent (BOLD) responses to electrical stimulation of fore- and hindpaws. The BOLD patterns observed match the known representations of fore- and hindpaws in the somatosensory cortex in rats. Preliminary results on BOLD signal enhancement using aminophylline are also presented.
Journal of Neuroscience Methods.
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ABSTRACT: Gene expression patterns were examined in lens epithelial cells conditioned to grow in 125 μM hydrogen peroxide in order to define the protective mechanisms that may be involved in survival during oxidative stress. RNA was extracted from normal and hydrogen peroxide-resistant αTN4 mouse lens epithelial cells. Gene expression was evaluated using Differential Display (DD) and RT-PCR. Upregulation of mRNAs for antioxidant and cellular defense enzymes was observed. The highest elevation detected was a 14-fold increase in catalase in the hydrogen peroxide-resistant cells. Glutathione peroxidase, ferritin, and αB-crystallin were upregulated 2-fold, and reticulocalbin was upregulated 6-fold in the resistant cells. αA-crystallin was downregulated 5-fold, while aldose reductase and mitochondrial gene products were unchanged. Thus, in the αTN4 mouse lens cell line, long-term exposure to high levels of hydrogen peroxide elicited an upregulation of transcripts for enzymes involved in hydrogen peroxide degradation, metal binding, and chaperone function. Since mitochondrial gene transcription is sensitive to hydrogen peroxide, the presence of normal levels of mitochondrial transcripts, in this study, demonstrates the effectiveness of the antioxidant defense systems.
Free Radical Biology and Medicine.
