X-ray-absorption studies of Nd2-xCexCuO4.
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Journal Article↗
Biomedical subjects
G Cao
Publications and source records attributed to G Cao.
Association between rat serum cholinesterase and some phospholipid components of lipoproteins in thioacetamide-induced hepatic injury.
Rat serum lipoprotein phospholipids and serum cholinesterase activity in control and thioacetamide-treated rats (50 mg/kg/day for 30 days) were studied. Analyses were done after 1, 3, 8 and 30 intraperitoneal doses of thioacetamide or 0.15 mol/l NaCl. Cholinesterase activity significantly increased with thioacetamide treatment. Only two phospholipids: LDL-phosphatidylcholine and HDL-lysophosphatidylcholine appeared associated with cholinesterase activity. LDL-phosphatidylcholine increased through the action of hepatotoxic thioacetamide while HDL-lysophosphatidylcholine significantly decreased. Because of the high statistically significant association between changes in these lipoprotein phospholipids and in cholinesterase in this model of hepatic injury, we conclude that cholinesterase could be involved in the regulation of these phospholipid levels.
Acetamides↗
Photoemission and oxygen K-edge absorption studies of Ba(Pb,Bi)O3.
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Journal Article↗
Changes in serum cholinesterase (EC 3.1.1.8) activity in rats consuming a high-fat diet.
Adult male rats were fed on a control diet containing (g/kg) carbohydrate 600, lipid 35 and protein 190, or on a high-fat diet containing carbohydrate 360, lipid 420 and protein 120. After 30 d, the high-fat diet provoked a decrease in serum cholinesterase (EC 3.1.1.8) activity which was reversed by feeding rats on the control diet. The observed decrease after 90 d on the high-fat diet was not seen if a simultaneous daily intraperitoneal injection of a lipotrophic agent containing (mg/kg) S-adenosyl-L-methionine 3, coenzyme A 0.1, UDP-glucose 30 and CDP-choline 1.5 was given to rats on the high-fat diet. The findings are discussed in relation to the apparent susceptibility of serum cholinesterase to dietary components and its possible role in lipid metabolism.
Animals↗
Structure of [Mg(HO3PCH(C6H5)2)2].8H2O, a layered phosphonate salt.
Bis(hydrogen diphenylmethylphosphonato)-magnesium octahydrate, [Mg(C13H12O3P)2].8H2O. Mr = 662.85, triclinic, P1, a = 6.1051 (15), b = 8.8308(14), c = 15.312(3) A, alpha = 78.514(13), beta = 83.993(11), gamma = 75.772(15) degrees, V = 782.8(3) A3, Z = 1, Dx = 1.41 g cm-3 (163 K), Mo K alpha, lambda = 0.71069 A, mu = 2.171 cm-1, F(000) = 350, T = 163 K, R = 0.0351 for 3749 reflections [F0 greater than or equal to 4 sigma(F0)]. The structure consists of alternating polar and nonpolar layers stacked along the crystallographic c axis. The polar layers contain Mg(H2O)26+ ions, water of hydration and the phosphonate O atoms, and the nonpolar layers contain the benzhydryl groups. Two-dimensional hydrogen-bonding networks link Mg(H2O)26+ and the water of hydration to the phosphonate O atoms. The shortest hydrogen bonds in the structure, 1.68(2) A, connect the P-OH H atom and the water of hydration. Slightly longer contacts [1.79(2), 1.85(2), 1.91(2), 1.92(2) A] connect the phosphonate O atoms (O1 and O3) to the H atoms of the Mg(H2O)26+ group. The coordination environment of the Mg atom is a very nearly regular octahedron of water O atoms.
Chemical Phenomena↗
Reduction of partial-volume artifacts with zero-filled interpolation in three-dimensional MR angiography.
Partial-volume artifacts reduce vessel contrast and continuity (especially in small vessels) in magnetic resonance (MR) angiography. The authors applied zero-filled (band-limited) interpolation to three-dimensional (3D) MR angiograms to reduce partial-volume artifacts. They demonstrated that zero-filled interpolation can also be implemented by means of voxel shifting in real space. Voxel-shifted interpolation is much less computer memory intensive than conventional zero-filled interpolation. They numerically simulated the contrast loss due to partial-volume artifacts and contrast recovery obtained with zero-filled interpolation. Zero-filled interpolation in all three orthogonal directions was applied to 3D MR angiography data sets from 29 human studies. These studies were obtained with the three commonly used 3D MR angiography techniques: 3D time of flight, multislab 3D time of flight, and 3D phase contrast. A substantial improvement in vessel contrast and vessel continuity was observed in all cases.
Adult↗
Experimental and theoretical studies of vessel contrast-to-noise ratio in intracranial time-of-flight MR angiography.
CNR studies were performed for human intracranial vessels in 3D MRA data sets. The CNR dependency of different imaging parameters, such as flip angle, field of view, echo time, repetition time, and echo readout symmetry, was studied for vessels in the region of the circle of Willis. A theoretical model was developed for MR vascular imaging based on the Bloch equations and Fourier imaging theory. This model predicts the MR image intensity of vessels from basic subject parameters, such as the relaxation times of blood and stationary tissue, vessel dimension, and flow velocity, and the parameters of the imaging technique, such as flip angle, voxel volume, repetition time, and echo time. For most experiments, the model was found to fit the experimental results well. The validity of this model allows the optimization of imaging parameters to maximize vessel CNR in MR angiography.
Adult↗
High concentrations of antioxidants may not improve defense against oxidative stress.
It is often assumed that the oxygen radical defense could be further improved by higher concentration of antioxidants. But this has not been demonstrated over a wide range of concentrations. There are different types of oxygen radicals produced in the body and the antioxidant protection against them may not positively related to their concentrations. We report here that by using H(2)O(2) with Cu(2+) as an hydroxyl-radical generator in vitro, ascorbic acid shows no oxygen-radical absorbing capacity. We also found that the net hydroxyl-radical absorbing capacity of a water soluble alpha-tocopherol analogue (Trolox) and uric acid increases with concentration only when the concentration is lower than the normal value found for alpha-tocopherol and uric acid in human serum. At higher concentrations, the hydroxyl-radical absorbing capacity of the alpha-tocopherol analogue and uric acid decreases. The mechanism involved in the decrease of hydroxyl radical absorbance capacity of Trolox and uric acid at high concentration may be related to their reaction with hydroxyl radicals or other oxygen radicals produced in the presence of both H(2)O(2) and Cu(2+). This kind of reaction could lead to the formation of additional many Trolox or uric acid radicals at the same time. These results may be important not only in evaluating antioxidant activities of antioxidants in vitro but also in studying the potential efficiency of antioxidants in vivo in affecting oxidative stress status.
Journal Article↗
Antioxidant capacity decreases during growth but not aging in rat serum and brain.
The objective of this study was to evaluate the effects of growth and aging on the antioxidant capacities of rat serum and brain, by using two different reactive oxygen species (ROS) generators and two different methods of expressing the results. The antioxidant capacity was determined by using the oxygen radical absorbance capacity (ORAL) assay. The protein content of serum increased significantly during the growth period of day 1 to 6 months of age. The protein content in brain (cortex and cerebellum) extract also tended to increase with the growth. The antioxidant capacity of serum decreased during growth, if the ORAC values were expressed on the basis of serum protein concentration. The antioxidant capacity in brain cortex and cerebellum declined significantly during growth, regardless of which ROS generator was used in the ORAC assay or how the results were expressed (units/ml or units/mg protein). Therefore, the rat pups had higher antioxidant capacity than the adult and old rats. The low plasma antioxidant capacity reported in premature neonates may simply result from a low protein concentration of the plasma, which occurs in neonates. No aging effect was observed on the antioxidant capacity of serum and brain in the adult and old rats.
Journal Article↗
Calcium-dependent pro-cholecystokinin V-9-M immunoreactive peptide release from rat brain slices and CCK-secreting rat medullary thyroid carcinoma cells in culture.
The release of peptides immunoreactive for a synthetic peptide (V-9-M) contained in the amino-terminal of pro-CCK was examined. The potassium-evoked release of V-9-M immunoreactive peptides from rat cerebral cortical slices in vitro was calcium dependent. Cholecystokinin-secreting rat medullary thyroid carcinoma cells also secreted significant quantities of these peptides. Sephadex column chromatography of the release media from slices and cells showed two V-9-M immunoreactive peptides, one larger and one smaller than V-9-M itself. Previous behavioral studies have suggested that V-9-M has a distinct neuropharmacological profile. These results demonstrate that V-9-M-like peptides are released along with CCK-8 and are consistent with the hypothesis that V-9-M-like peptides may be neurotransmitters or neuromodulators or may be involved in the sorting or transport of CCK-8.
Amino Acid Sequence↗
Analysis of the human carcinoembryonic antigen promoter core region in colorectal carcinoma-selective cytosine deaminase gene therapy.
We isolated a 204-base pair carcinoembryonic antigen (CEA) promoter core region from a CEA-producing human colorectal carcinoma (CRC) and constructed retrovirus vectors carrying the expression cassette consisting of the CEA promoter core region and the cytosine deaminase (CD) gene. pCD2 retrovirus carrying the CD gene directed by the retrovirus long terminal repeat promoter served as a control vector. An in vitro study showed that the CEA promoter conferred CEA-producing cell-selective CD expression, specifically when the CD expression cassette was inserted into the 3' long terminal repeat of the retrovirus vector. CD-modified CRC xenografts in nude mice were sensitive to 5-fluorocytosine and caused a profound bystander effect on the unmodified CRC. When nude mice harboring intraperitoneally disseminated CRCs were injected intraperitoneally with the CD expression cassette-carrying retrovirus-producing cells, CD transduction into the disseminated CRCs and bone marrow (BM) was observed. CD expression was, however, restricted to CRCs, and it was observed in both CRCs and BM of mice injected with pCD2 retrovirus-producing cells, resulting in better therapeutic outcomes without BM suppression. These results indicate that effective and safe in vivo gene therapy for CRC may be feasible by transferring the CD gene controlled by the CEA promoter core region.
Animals↗
A safe, effective in vivo gene therapy for melanoma using tyrosinase promoter-driven cytosine deaminase gene.
This study was designed to develop a safe, effective gene therapy for disseminated melanoma. We constructed retroviral vectors containing a tyrosinase promoter-cytosine deaminase expression cassette (Tyr/CD), and demonstrated that the tyrosinase promoter conferred a selective expression of cytosine deaminase (CD) gene in B16 melanoma cells, especially when the Tyr/CD cassette inserted in 3'LTR region of a retroviral vector. In vivo gene therapy for the intraperitoneally disseminated melanoma using Tyr/CD retrovirus-producing cells and 5-fluorocytosine (5-FC) showed that retroviruses produced in situ were capable of infecting tumor xenografts and bone marrow cells in animal model, and survival rates were prolonged significantly as compared with those treated with CD2 retrovirus-producing cells and 5-FC. Importantly, the treatment-related bone marrow suppression was not observed in the former treatment, while profound bone marrow suppression was observed in the latter treatment. In vivo gene therapy using retrovirus-producing cells containing suicide gene under the control of a tissue-specific promoter and 5-FC administration is safer and more effective for the treatment of disseminated melanoma, as compared with retrovirus-producing cells containing the gene under the control of a universal promoter and 5-FC.
Animals↗
Analysis of botanicals and dietary supplements for antioxidant capacity: a review.
Free radicals and other reactive species are considered to be important causative factors in the development of diseases of aging such as cancer and cardiovascular diseases. This relationship has led to considerable interest in assessing the antioxidant capacity of foods and botanicals and other nutritional antioxidant supplements. The use of the oxygen radical absorbance capacity (ORAC) assay as a tool for antioxidant assessment is described and proposed as a method for comparing botanical sources and for standardizing nutritional supplements. The free radical or oxidant source is important and direct comparisons cannot be made between procedures that use different sources. The ORAC procedure uses 2,2'-azobis(2-amidinopropane) dihydrochloride as a peroxyl radical source, which is relevant to biological systems because the peroxyl radical is the most abundant free radical. Other oxidant sources (hydroxyl radical and Cu++) can also be used to characterize antioxidants in botanicals. Phenolics or polyphenolics are responsible for most of the antioxidant capacity in fruits, vegetables, and most botanical antioxidant supplements. Although little is known about the absorption and metabolism of these components, improvement in the in vivo antioxidant status has been observed in human subjects following consumption of antioxidant botanicals. The ORAC method provides a basis from which to establish appropriate dietary intakes that might impact health outcomes.
Absorption↗