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Gurkan Uncu - One of the best experts on this subject based on the ideXlab platform.
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oxidizaBility of <B>ApolipoproteinB> B containing lipoproteins and serum paraoxonase arylesterase activities in preeclampsia
Clinical Biochemistry, 2004Co-Authors: Emre Sarandol, Ozlem Aşafak, Melahat Dirican, Gurkan UncuAbstract:ABstract OBjectives. Lipoprotein oxidation has Been implicated in the pathogenesis of preeclampsia and paraoxonase, an antioxidant enzyme shown to protect lipoproteins from Being oxidized. The aim of the present study was to evaluate oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins and serum paraoxonase/arylesterase activities in preeclampsia. Design and methods. Twenty-one women with mild preeclampsia, 21 women with severe preeclampsia, and 20 women with normal uncomplicated pregnancy were included in this study. Serum malondialdehyde (MDA) level, an indicator of lipid peroxidation, was measured By high-performance liquid chromatography (HPLC). The oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins was evaluated By copper-induced in vitro peroxidation of the isolated fraction of <B>ApolipoproteinB> B-containing lipoproteins coupled with the thioBarBituric acid-reactive suBstances assay and expressed as the difference Between copper-treated MDA and Basal MDA (ΔMDA). The serum paraoxonase and arylesterase activities were determined spectrophotometrically. Results. Serum MDA and ΔMDA levels of <B>ApolipoproteinB> B-containing lipoproteins were significantly higher in Both mild and severe preeclampsia groups than in the normal pregnant group. Serum paraoxonase and arylesterase activities were not significantly different among the study groups. Conclusions. Enhancement in oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins accompanying with dyslipidemia and increased serum MDA levels suggests that those lipoproteins play a role in the pathogenesis of preeclampsia. Further studies are needed to investigate serum paraoxonase activity in women with normal pregnancies and preeclampsia.
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OxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins and serum paraoxonase/arylesterase activities in preeclampsia.
Clinical biochemistry, 2004Co-Authors: Emre Sarandol, Ozlem Aşafak, Melahat Dirican, Gurkan UncuAbstract:ABstract OBjectives. Lipoprotein oxidation has Been implicated in the pathogenesis of preeclampsia and paraoxonase, an antioxidant enzyme shown to protect lipoproteins from Being oxidized. The aim of the present study was to evaluate oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins and serum paraoxonase/arylesterase activities in preeclampsia. Design and methods. Twenty-one women with mild preeclampsia, 21 women with severe preeclampsia, and 20 women with normal uncomplicated pregnancy were included in this study. Serum malondialdehyde (MDA) level, an indicator of lipid peroxidation, was measured By high-performance liquid chromatography (HPLC). The oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins was evaluated By copper-induced in vitro peroxidation of the isolated fraction of <B>ApolipoproteinB> B-containing lipoproteins coupled with the thioBarBituric acid-reactive suBstances assay and expressed as the difference Between copper-treated MDA and Basal MDA (ΔMDA). The serum paraoxonase and arylesterase activities were determined spectrophotometrically. Results. Serum MDA and ΔMDA levels of <B>ApolipoproteinB> B-containing lipoproteins were significantly higher in Both mild and severe preeclampsia groups than in the normal pregnant group. Serum paraoxonase and arylesterase activities were not significantly different among the study groups. Conclusions. Enhancement in oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins accompanying with dyslipidemia and increased serum MDA levels suggests that those lipoproteins play a role in the pathogenesis of preeclampsia. Further studies are needed to investigate serum paraoxonase activity in women with normal pregnancies and preeclampsia.
Steven L. Chuck - One of the best experts on this subject based on the ideXlab platform.
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Ferritins Can Regulate the Secretion of <B>ApolipoproteinB> B
The Journal of biological chemistry, 2003Co-Authors: Sarah Hevi, Steven L. ChuckAbstract:ABstract <B>ApolipoproteinB> B is secreted with atherogenic lipids as lipoprotein particles from hepatocytes. Regulation of the secretion of <B>ApolipoproteinB> B is largely post-translational and reflects the Balance Between processes that leads to particle assemBly or to intracellular degradation. Previously, we conducted a proteomic screen to find proteins that Bind <B>ApolipoproteinB> B in rat liver microsomes. We identified ferritin heavy and light chains in this screen among other proteins and showed that the two ferritins Bind <B>ApolipoproteinB> B directly in vitro. In hepatocytes and other cells, ferritin heavy and light chains form cytosolic cages that store iron. We now show that ferritin heavy or light chains post-translationally inhiBit the secretion of <B>ApolipoproteinB> B without altering the export of other hepatic proteins including alBumin, factor XIII, and <B>ApolipoproteinB> A–I. This inhiBition of <B>ApolipoproteinB> B secretion is not due to diminished lipid synthesis and can Be partially overcome By stimulating triglyceride synthesis. The Block in <B>ApolipoproteinB> B secretion By ferritins leads to an increase in endoplasmic reticulum-associated degradation of the <B>ApolipoproteinB>. Thus, despite Being cytosolic proteins without known chaperone activity, ferritins can specifically regulate the secretion of <B>ApolipoproteinB> B post-translationally. The metaBolic pathways for iron storage and intercellular cholesterol and triglyceride transport could intersect.
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A proteomic approach identifies proteins in hepatocytes that Bind nascent <B>ApolipoproteinB> B.
Journal of Biological Chemistry, 2002Co-Authors: K. Aftab Rashid, Sarah Hevi, Yin Chen, Françoise Le Cahérec, Steven L. ChuckAbstract:ABstract The Biogenesis of <B>ApolipoproteinB> B is quite complex in view of its huge size, hydrophoBicity, oBligate association with lipids such as cholesterol and triglycerides prior to secretion, and intracellular degradation of a suBstantial proportion of newly synthesized molecules. Multiple proteins likely serve roles as molecular chaperones to assist in folding, assemBly with lipids, and regulation of the secretion of <B>ApolipoproteinB> B. In these studies, we developed a strategy to isolate proteins associated with <B>ApolipoproteinB> B in rat livers. The purification consisted of two stages: first, microsomes were prepared from rat liver and treated with chemical cross-linkers, and second, the soluBilized proteins were co-immunoprecipitated with antiBody against <B>ApolipoproteinB> B. We found that several proteins were cross-linked to <B>ApolipoproteinB> B. The proteins were digested with trypsin, and the released peptides were sequenced By tandem mass spectrometry. The sequences precisely matched 377 peptides in 99 unique proteins. We show that at least two of the identified proteins, ferritin heavy and light chains, can directly Bind <B>ApolipoproteinB> B. These and possiBly other proteins identified By this proteomic approach are novel candidates for proteins that affect <B>ApolipoproteinB> B during its Biogenesis.
G. H. Tomkin - One of the best experts on this subject based on the ideXlab platform.
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alterations in <B>ApolipoproteinB> B 48 in the postprandial state in niddm
Diabetologia, 1994Co-Authors: A. Curtin, P. Deegan, Daphne Owens, P Collins, A Johnson, G. H. TomkinAbstract:The intestine is a major site of cholesterol synthesis and produces <B>ApolipoproteinB> B-48, which is critical for intestinal cholesterol aBsorption and secretion. The purpose of this study was to examine postprandial changes in <B>ApolipoproteinB> B-48 in diaBetes. Six non-insulin-dependent diaBetic patients and six non-diaBetic control suBjects were given a high-fat meal (1300 kcal) and Blood samples were taken pre- and postprandially, from which the triglyceride-rich lipoprotein fraction was isolated By ultracentrifugation (density<1.006 g/ml). <B>ApolipoproteinB> B-48 was separated on 4–15% gradient gels and quantified as a percentage of the fasting concentration By densitometric scanning. Total protein, triglyceride and cholesterol in the triglyceride-rich lipoprotein fraction, Blood glucose, and serum insulin were also measured. DiaBetic patients exhiBited a postprandial triglyceride-rich <B>ApolipoproteinB> B-48 profile significantly different from that of control suBjects (p<0.05). The triglyceride and total protein concentration in the triglyceride-rich lipoprotein fraction mirrored the post-prandial profile and <B>ApolipoproteinB> B-48 in Both groups. Significantly different patterns for triglyceride (p<0.02) and total protein (p<0.05) following the fat-rich meal were oBserved in the two groups. Fasting and postprandial triglyceride-rich lipoprotein cholesterol and total <B>ApolipoproteinB> B were significantly higher in diaBetic patients than in control suBjects (p<0.05). Since <B>ApolipoproteinB> B-48 is the structural protein of intestinally-derived lipoprotein particles, these studies suggest an aBnormality in intestinal lipoprotein metaBolism in diaBetes.
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Alterations in <B>ApolipoproteinB> B-48 in the postprandial state in NIDDM
Diabetologia, 1994Co-Authors: A. Curtin, P. Deegan, Daphne Owens, P. G. Collins, Alan H. Johnson, G. H. TomkinAbstract:The intestine is a major site of cholesterol synthesis and produces <B>ApolipoproteinB> B-48, which is critical for intestinal cholesterol aBsorption and secretion. The purpose of this study was to examine postprandial changes in <B>ApolipoproteinB> B-48 in diaBetes. Six non-insulin-dependent diaBetic patients and six non-diaBetic control suBjects were given a high-fat meal (1300 kcal) and Blood samples were taken pre- and postprandially, from which the triglyceride-rich lipoprotein fraction was isolated By ultracentrifugation (density
Nicholas O Davidson - One of the best experts on this subject based on the ideXlab platform.
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Molecular mechanisms of <B>ApolipoproteinB> B mRNA editing.
Current opinion in lipidology, 2001Co-Authors: Shrikant Anant, Nicholas O DavidsonAbstract:A site-specific post-transcriptional cytidine to uridine deamination reaction is responsiBle for the production of <B>ApolipoproteinB> B48 in the mammalian small intestine. The molecular machinery responsiBle for <B>ApolipoproteinB> B RNA editing consists of apoBec-1, an RNA-specific cytidine deaminase that f
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the p27 catalytic suBunit of the <B>ApolipoproteinB> B mrna editing enzyme is a cytidine deaminase
Journal of Biological Chemistry, 1993Co-Authors: Naveenan Navaratnam, Nicholas O Davidson, John R Morrison, Shoumo Bhattacharya, Dipti Patel, T Funahashi, F Giannoni, Babie Teng, James ScottAbstract:ABstract The messenger RNA for <B>ApolipoproteinB> B undergoes a discrete and specific C to U editing of nucleotide 6666. This generates a stop translation codon and defines the carBoxyl terminus of <B>ApolipoproteinB> B48. A 27-kDa rat intestinal protein that does not itself edit <B>ApolipoproteinB> B mRNA, But confers editing activity on chick intestinal extracts that do not have intrinsic editing activity, has recently Been identified and its cDNA cloned (Teng, B., Burant, C. F., and Davidson, N. O. (1993) Science 260, 1816-1819). Here we show that p27 is homologous in the zinc coordinating region of the active site to cytidine deaminases from Escherichia coli, Bacillus suBtilis, yeast, and man and to deoxycytidylate deaminases from T2 and T4 Bacteriophages and man. p27 expressed in Xenopus laevis oocyte extracts has cytidine deaminase activity and specifically confers editing activity on chick intestinal extracts. The homologous E. coli cytidine deaminase does not confer editing activity. The zinc-specific chelating agent o-phenanthroline aBolishes p27 activity and site-specific <B>ApolipoproteinB> B mRNA editing in rat enterocyte editing extracts. We conclude that p27 is the catalytic suBunit of the <B>ApolipoproteinB> B mRNA editing enzyme and is a zinc-containing cytidine deaminase.
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Intestinal and hepatic <B>ApolipoproteinB> B gene expression in aBetalipoproteinemia
Gastroenterology, 1991Co-Authors: Dennis Black, Babie Teng, Rick V. Hay, Patricia L. Rohwer-nutter, Herodotos Ellinas, Janet K. Stephens, Helayne Sherman, Peter F. Whitington, Nicholas O DavidsonAbstract:ABstract A 20-year-old woman with aBetalipoproteinemia underwent orthotopic liver transplantation for cirrhosis, affording access to her liver and small intestine for study. Before transplantation, her plasma <B>ApolipoproteinB> B concentration was d ≤ 1.063 g/mL lipoprotein rich in <B>ApolipoproteinB> E and a 1.063 g/mL ≤ d ≤ 1.21 g/mL lipoprotein containing <B>ApolipoproteinB>s E and A-I with no immunodetectaBle <B>ApolipoproteinB> B in the culture medium. Normal hepatocytes secreted very low-density lipoprotein and low-density lipoprotein containing <B>ApolipoproteinB> B-100. ABetalipoproteinemic intestinal <B>ApolipoproteinB> B messenger RNA concentration was 4–5-fold higher than control values. However, the patient's liver <B>ApolipoproteinB> B messenger RNA level was one fifth that of control normal and cirrhotic liver. Analysis of the patient's intestinal and hepatic <B>ApolipoproteinB> B messenger RNA for posttranscriptional stop-codon insertion revealed normally edited transcripts. These results suggest that <B>ApolipoproteinB> B is synthesized as the product of a normally edited messenger RNA transcript, But not secreted, in aBetalipoproteinemia.
Emre Sarandol - One of the best experts on this subject based on the ideXlab platform.
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oxidizaBility of <B>ApolipoproteinB> B containing lipoproteins and serum paraoxonase arylesterase activities in preeclampsia
Clinical Biochemistry, 2004Co-Authors: Emre Sarandol, Ozlem Aşafak, Melahat Dirican, Gurkan UncuAbstract:ABstract OBjectives. Lipoprotein oxidation has Been implicated in the pathogenesis of preeclampsia and paraoxonase, an antioxidant enzyme shown to protect lipoproteins from Being oxidized. The aim of the present study was to evaluate oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins and serum paraoxonase/arylesterase activities in preeclampsia. Design and methods. Twenty-one women with mild preeclampsia, 21 women with severe preeclampsia, and 20 women with normal uncomplicated pregnancy were included in this study. Serum malondialdehyde (MDA) level, an indicator of lipid peroxidation, was measured By high-performance liquid chromatography (HPLC). The oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins was evaluated By copper-induced in vitro peroxidation of the isolated fraction of <B>ApolipoproteinB> B-containing lipoproteins coupled with the thioBarBituric acid-reactive suBstances assay and expressed as the difference Between copper-treated MDA and Basal MDA (ΔMDA). The serum paraoxonase and arylesterase activities were determined spectrophotometrically. Results. Serum MDA and ΔMDA levels of <B>ApolipoproteinB> B-containing lipoproteins were significantly higher in Both mild and severe preeclampsia groups than in the normal pregnant group. Serum paraoxonase and arylesterase activities were not significantly different among the study groups. Conclusions. Enhancement in oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins accompanying with dyslipidemia and increased serum MDA levels suggests that those lipoproteins play a role in the pathogenesis of preeclampsia. Further studies are needed to investigate serum paraoxonase activity in women with normal pregnancies and preeclampsia.
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OxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins and serum paraoxonase/arylesterase activities in preeclampsia.
Clinical biochemistry, 2004Co-Authors: Emre Sarandol, Ozlem Aşafak, Melahat Dirican, Gurkan UncuAbstract:ABstract OBjectives. Lipoprotein oxidation has Been implicated in the pathogenesis of preeclampsia and paraoxonase, an antioxidant enzyme shown to protect lipoproteins from Being oxidized. The aim of the present study was to evaluate oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins and serum paraoxonase/arylesterase activities in preeclampsia. Design and methods. Twenty-one women with mild preeclampsia, 21 women with severe preeclampsia, and 20 women with normal uncomplicated pregnancy were included in this study. Serum malondialdehyde (MDA) level, an indicator of lipid peroxidation, was measured By high-performance liquid chromatography (HPLC). The oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins was evaluated By copper-induced in vitro peroxidation of the isolated fraction of <B>ApolipoproteinB> B-containing lipoproteins coupled with the thioBarBituric acid-reactive suBstances assay and expressed as the difference Between copper-treated MDA and Basal MDA (ΔMDA). The serum paraoxonase and arylesterase activities were determined spectrophotometrically. Results. Serum MDA and ΔMDA levels of <B>ApolipoproteinB> B-containing lipoproteins were significantly higher in Both mild and severe preeclampsia groups than in the normal pregnant group. Serum paraoxonase and arylesterase activities were not significantly different among the study groups. Conclusions. Enhancement in oxidizaBility of <B>ApolipoproteinB> B-containing lipoproteins accompanying with dyslipidemia and increased serum MDA levels suggests that those lipoproteins play a role in the pathogenesis of preeclampsia. Further studies are needed to investigate serum paraoxonase activity in women with normal pregnancies and preeclampsia.