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1
Ferenczi, Alejandra, Nobuko Sugimoto, and Randolph M. Beaudry. "Emission Patterns of Esters and Their Precursors Throughout Ripening and Senescence in ‘Redchief Delicious’ Apple Fruit and Implications Regarding Biosynthesis and Aroma Perception." Journal of the American Society for Horticultural Science 146, no. 5 (September 2021): 297–328. http://dx.doi.org/10.21273/jashs05064-21.
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The volatile profile of ‘Redchief Delicious’ apple (Malus ×domestica Borkh.) fruit was evaluated at 18 time points from 3 weeks before to 8 weeks after onset of autocatalytic ethylene production to capture the dynamics associated with development from mature green to senescent fruit. Minor amounts of ester production began several days before the onset of ethylene production. Ester production rose rapidly as internal ethylene levels increased beyond 22 nmol·L−1 (0.5 µL·L−1). Peak ester production roughly coincided with maximum ethylene synthesis, declining thereafter. Ester production was further evaluated according to the acid- (alkanoate) and alcohol- (alkyl) derived portions of the ester. The maximum rate of production for a given ester tended to occur later in development as the chain length of the alcohol-derived portion declined. The production rate for many esters paralleled the rate of emanation of their respective alcohol substrates, suggesting that availability of the alcohols limits ester production more than availability of the acid substrates. Combining production rates with sensory descriptors and human sensitivity to individual volatiles permitted approximations of aroma sensations likely engendered by the fruit throughout ripening. Overripe and alcoholic sensations are predicted to increase 2 weeks after the initiation of ripening in response to an increase in the production of ethyl esters. Acetate esters predominated, comprising 50% to 80% of esters throughout maturation and ripening, indicating that the substrate acetyl-CoA may be at saturating levels for alcohol acyl transferase (AAT) at the final step of ester formation. Acetate feeding did not enhance ester production, although label from 13C-acetate was extensively incorporated into esters. The data are consistent with the action of multiple AAT isozymes differing in activity and substrate preference. Incorporation of labeled 13C-acetate into precursors of esters, alcohols, and acids, reflected ester biosynthesis via 1- and 2-carbon chain elongation pathways in ripening ‘Redchief Delicious’ apple fruit.
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Jayanty, Sastry, Jun Song, Nicole M. Rubinstein, Andrés Chong, and Randolph M. Beaudry. "Temporal Relationship between Ester Biosynthesis and Ripening Events in Bananas." Journal of the American Society for Horticultural Science 127, no. 6 (November 2002): 998–1005. http://dx.doi.org/10.21273/jashs.127.6.998.
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The temporal relationship between changes in ethylene production, respiration, skin color, chlorophyll fluorescence, volatile ester biosynthesis, and expression of ACC oxidase (ACO) and alcohol acyl-CoA transferase (AAT) in ripening banana (Musa L. spp., AAA group, Cavendish subgroup. `Valery') fruit was investigated at 22 °C. Ethylene production rose to a peak a few hours after the onset of its logarithmic phase; the peak in production coincided with maximal ACO expression. The respiratory rise began as ethylene production increased, reaching its maximum ≈30 to 40 hours after ethylene production had peaked. Green skin coloration and photochemical efficiency, as measured by chlorophyll fluorescence, declined simultaneously after the peak in ethylene biosynthesis. Natural ester biosynthesis began 40 to 50 hours after the peak in ethylene biosynthesis, reaching maximal levels 3 to 4 days later. While AAT expression was detected throughout, the maximum level of expression was detected at the onset of natural ester biosynthesis. The synthesis of unsaturated esters began 100 hours after the peak in ethylene and increased with time, suggesting the lipoxygenase pathway be a source of ester substrates late in ripening. Incorporation of exogenously supplied ester precursors (1-butanol, butyric acid, and 3-methyl-1-butanol) in the vapor phase into esters was maturity-dependent. The pattern of induced esters and expression data for AAT suggested that banana fruit have the capacity to synthesize esters over 100 hours before the onset of natural ester biosynthesis. We hypothesize the primary limiting factor in ester biosynthesis before natural production is precursor availability, but, as ester biosynthesis is engaged, the activity of alcohol acyl-CoA transferase the enzyme responsible for ester biosynthesis, exerts a major influence.
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Saerens, S. M. G., F. Delvaux, K. J. Verstrepen, P. Van Dijck, J. M. Thevelein, and F. R. Delvaux. "Parameters Affecting Ethyl Ester Production by Saccharomyces cerevisiae during Fermentation." Applied and Environmental Microbiology 74, no. 2 (November 9, 2007): 454–61. http://dx.doi.org/10.1128/aem.01616-07.
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ABSTRACT Volatile esters are responsible for the fruity character of fermented beverages and thus constitute a vital group of aromatic compounds in beer and wine. Many fermentation parameters are known to affect volatile ester production. In order to obtain insight into the production of ethyl esters during fermentation, we investigated the influence of several fermentation variables. A higher level of unsaturated fatty acids in the fermentation medium resulted in a general decrease in ethyl ester production. On the other hand, a higher fermentation temperature resulted in greater ethyl octanoate and decanoate production, while a higher carbon or nitrogen content of the fermentation medium resulted in only moderate changes in ethyl ester production. Analysis of the expression of the ethyl ester biosynthesis genes EEB1 and EHT1 after addition of medium-chain fatty acid precursors suggested that the expression level is not the limiting factor for ethyl ester production, as opposed to acetate ester production. Together with the previous demonstration that provision of medium-chain fatty acids, which are the substrates for ethyl ester formation, to the fermentation medium causes a strong increase in the formation of the corresponding ethyl esters, this result further supports the hypothesis that precursor availability has an important role in ethyl ester production. We concluded that, at least in our fermentation conditions and with our yeast strain, the fatty acid precursor level rather than the activity of the biosynthetic enzymes is the major limiting factor for ethyl ester production. The expression level and activity of the fatty acid biosynthetic enzymes therefore appear to be prime targets for flavor modification by alteration of process parameters or through strain selection.
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Udry, Christopher. "Esther Duflo: 2010 John Bates Clark Medalist." Journal of Economic Perspectives 25, no. 3 (August 1, 2011): 197–216. http://dx.doi.org/10.1257/jep.25.3.197.
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Esther Duflo, winner of the 2010 John Bates Clark Medal, has made extraordinary contributions to development economics. She exemplifies and has played a vital role in the renaissance of development economics over the past decade. She has erected and inspired a research apparatus all over the developing world that integrates large-scale field experiments with economic theory to yield important insights for development policy and our understanding of behavior and institutions in developing countries. I'll divide my discussion of Esther's work into four categories: educational production, the economic lives of the poor, women as decisionmakers, and a broad category of market and policy failures. I will then offer some thoughts on Esther's role as a scholar–activist.
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Rodriguez, K. A., and A. T. Tsin. "Retinyl esters in the vertebrate neuroretina." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 256, no. 1 (January 1, 1989): R255—R258. http://dx.doi.org/10.1152/ajpregu.1989.256.1.r255.
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High-performance liquid chromatography (HPLC) was employed to measure retinyl esters in the vertebrate retina. Both retina and retinal pigment epithelium (RPE) from frog, chicken, and bovine eyes were studied. In comparison to the RPE, the retina possessed a significant level of 11-cis and all trans retinyl palmitate. Using a sensitive radioassay, we also detected the presence of retinyl ester hydrolase (REH) activity in homogenates prepared from both retina and RPE. The rate of retinyl ester hydrolysis in these retinas was sufficiently high to supply retinal chromophores for the metabolic renewal and for the regeneration of visual pigments. In comparison to retinyl esters in the RPE, retinyl esters in the retina are located much closer to the sites of visual pigment synthesis and regeneration. Hence it is possible that these retinyl esters play a more important role in the visual cycle than those in the RPE.
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Braun, Derek C., Yeyu Cao, Shaomeng Wang, Susan H. Garfield, Gang Min Hur, and Peter M. Blumberg. "Role of phorbol ester localization in determining protein kinase C or RasGRP3 translocation: Real-time analysis using fluorescent ligands and proteins." Molecular Cancer Therapeutics 4, no. 1 (January 1, 2005): 141–50. http://dx.doi.org/10.1158/1535-7163.141.4.1.
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Abstract The diacylglycerol signaling pathway, involving protein kinase C (PKC) and RasGRP, is a promising therapeutic target for both cancer and other indications. The phorbol esters, ultrapotent diacylglycerol analogues, bind to and activate PKC and RasGRP. Here, using fluorescent phorbol esters and complementary fluorescent PKC and RasGRP constructs, we determined the localization of the phorbol ester as a function of time after addition and how the resultant PKC or RasGRP3 translocation related to ligand localization. For these studies, we prepared fluorescently labeled phorbol esters of varying lipophilicities based on the BODIPY FL (green) or BODIPY 581/591 (red) fluorophores, and by using fusion constructs of green fluorescent protein or DsRed with PKC isoforms or RasGRP3 expressed in Chinese hamster ovary cells, we simultaneously compared the kinetics and pattern of localization of PKC or RasGRP3 with that of the fluorescent red or green phorbol esters. Binding assays showed that the fluorescent derivatives were potent ligands. Uptake followed a one-compartment pharmacokinetic model with a half-time of minutes to hours, depending on the ligand, and all of the fluorescent phorbol esters localized primarily to intracellular membranes, with little plasma membrane localization. The fluorescent phorbol esters induced translocation of and generally colocalized with PKCδ or RasGRP3. However, PKCα and, initially, PKCδ, translocated to the plasma membrane, in which little phorbol ester accumulated. The findings argue that the rate of uptake of phorbol esters influences the subsequent pattern of PKCδ translocation, and that the specificity for PKCα translocation is dominated by factors other than the localization of the ligand.
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Mei, Shuang, Haihua Gu, Adam Ward, Xuefeng Yang, Huailan Guo, Ka He, Zhenqi Liu, and Wenhong Cao. "p38 Mitogen-activated Protein Kinase (MAPK) Promotes Cholesterol Ester Accumulation in Macrophages through Inhibition of Macroautophagy." Journal of Biological Chemistry 287, no. 15 (February 21, 2012): 11761–68. http://dx.doi.org/10.1074/jbc.m111.333575.
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p38 MAPK has been strongly implicated in the development of atherosclerosis, but its role in cholesterol ester accumulation in macrophages and formation of foam cells, an early step in the development of atherosclerosis, has not been investigated. We addressed this issue and made some brand new observations. First, elevated intracellular cholesterol level induced by the exposure to LDL-activated p38 MAPK and activation of p38 MAPK with anisomycin increased the ratio of cholesterol esters over free cholesterol, whereas inhibition of p38 MAPK with SB203580 or siRNA reduced the LDL loading-induced intracellular accumulation of free cholesterol and cholesterol esters in macrophages. Second, exposure to LDL cholesterol inhibited autophagy in macrophages, and inhibition of autophagy with 3-methyladenine increased intracellular accumulation of cholesterol (free cholesterol and cholesterol esters), whereas activation of autophagy with rapamycin decreased intracellular accumulation of free cholesterol and cholesterol esters induced by the exposure to LDL cholesterol. Third, LDL cholesterol loading-induced inhibition of autophagy was prevented by blockade of p38 MAPK with SB203580 or siRNA. Neutral cholesterol ester hydrolase was co-localized with autophagosomes. Finally, LDL cholesterol loading and p38 activation suppressed expression of the key autophagy gene, ulk1, in macrophages. Together, our results provide brand new insight about cholesterol ester accumulation in macrophages and foam cell formation.
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Hamilton, J. J., and P. Hahn. "Carnitine and carnitine esters in rat bile and human duodenal fluid." Canadian Journal of Physiology and Pharmacology 65, no. 9 (September 1, 1987): 1816–20. http://dx.doi.org/10.1139/y87-283.
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The recent discovery of carnitine and its esters in rat bile has led to much speculation about its role. The objectives of these studies were to investigate the origin of carnitine esters in rat bile and to study the presence of carnitine in human bile-rich duodenal fluid. Bile was collected from chow-fed (n = II), fasted (72 h, n = 6), and fasted plus 2-tetradecylglycidic acid administered (72 h, n = 5) male adult rats under sodium pentobarbital anaesthesia. Carnitine and carnitine ester content was measured in the bile and compared with serum and liver carnitine. Bile from fed rats was found to contain 80% acylcarnitine, one-third of this as long chain carnitine esters. Fasting caused no change in the secretion rate of acylcarnitine into the bile, although long chain carnitine ester secretion almost doubled. Conversely, 2-tetradecylglycidic acid treatment caused a decrease in long chain carnitine ester secretion into bile. Duodenal fluid was collected from patients with suspected cholelithiasis (n = 10) before and after pancreozymin–cholecystokinin injection. Although carnitine concentration was variable, it was consistently 80% esterified. These data associate bile carnitine with hepatic carnitine metabolism and establish the presence of carnitine and carnitine esters in the human intestinal lumen.
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Sesar, Kristina. "Young People Who Sext: The Role of Self-Esteem and Body-Esteem." Central European Journal of Paediatrics 17, no. 1 (March 24, 2021): 52–65. http://dx.doi.org/10.5457/p2005-114.288.
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Almahbobi, G., and P. F. Hall. "The role of intermediate filaments in adrenal steroidogenesis." Journal of Cell Science 97, no. 4 (December 1, 1990): 679–87. http://dx.doi.org/10.1242/jcs.97.4.679.
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Cholesterol is stored in adrenal cells as ester in lipid droplets, which are transported to mitochondria to provide a substrate for steroid hormone synthesis. Using mouse adrenal tumour cells (Y-1), we show here that approximately 33% of the adrenal cell cholesterol ester is bound tightly to intermediate filaments while the rest is either loosely attached or free in the cytosol. Specific binding of droplets to intermediate filaments was demonstrated by immunofluorescence and electron microscopy. Immunofluorescence was based upon Nile Red to stain lipid and antibodies to vimentin, actin and tubulin. Electron microscopy, including immunoelectron microscopy with protein A conjugated to gold particles (5 nm), was used to examine whole mounts of cytoskeletons and intermediate filaments. Immunofluorescence reveals that bound droplets are surrounded by a capsule containing vimentin and can be removed from the filaments by extraction with ethanol or 6 M urea. Negative staining of the urea extracts revealed isolated droplets. To the extent that cholesterol ester is the storage form of steroidogenic cholesterol, the knowledge that lipid droplets containing such esters are attached to intermediate filaments may prove important in unravelling the complex process of the transport of cholesterol to mitochondria.
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Ishige, Takeru, Akio Tani, Keiji Takabe, Kazunori Kawasaki, Yasuyoshi Sakai, and Nobuo Kato. "Wax Ester Production from n-Alkanes by Acinetobacter sp. Strain M-1: Ultrastructure of Cellular Inclusions and Role of Acyl Coenzyme A Reductase." Applied and Environmental Microbiology 68, no. 3 (March 2002): 1192–95. http://dx.doi.org/10.1128/aem.68.3.1192-1195.2002.
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ABSTRACT Acinetobacter sp. strain M-1 accumulated a large amount of wax esters from an n-alkane under nitrogen-limiting conditions. Under the optimized conditions with n-hexadecane as the substrate, the amount of hexadecyl hexadecanoate in the cells reached 0.17 g/g of cells (dry weight). Electron microscopic analysis revealed that multilayered disk-shaped intracellular inclusions were formed concomitant with wax ester formation. The contribution of acyl-CoA reductase to wax ester synthesis was evaluated by gene disruption analysis.
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Rajendran, Aravindan, Anbumathi Palanisamy, and Viruthagiri Thangavelu. "Lipase catalyzed ester synthesis for food processing industries." Brazilian Archives of Biology and Technology 52, no. 1 (February 2009): 207–19. http://dx.doi.org/10.1590/s1516-89132009000100026.
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Lipases are one of the most important industrial biocatalyst which catalyzes the hydrolysis of lipids. It can also reverse the reaction at minimum water activity. Because of this pliable nature, it is widely exploited to catalyze the diverse bioconversion reactions, such as hydrolysis, esterification, interesterification, alcoholysis, acidolysis and aminolysis. The property to synthesize the esters from the fatty acids and glycerol promotes its use in various ester synthesis. The esters synthesized by lipase finds applications in numerous fields such as biodiesel production, resolution of the recemic drugs, fat and lipid modification, flavour synthesis, synthesis of enantiopure pharmaceuticals and nutraceuticals. It plays a crucial role in the food processing industries since the process is unaffected by the unwanted side products. Lipase modifications such as the surfactant coating, molecular imprinting to suit for the non-aqueous ester synthesis have also been reported. This review deals with lipase catalyzed ester synthesis, esterification strategies, optimum conditions and their applications in food processing industries.
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Verstrepen, Kevin J., Stijn D. M. Van Laere, Bart M. P. Vanderhaegen, Guy Derdelinckx, Jean-Pierre Dufour, Isak S. Pretorius, Joris Winderickx, Johan M. Thevelein, and Freddy R. Delvaux. "Expression Levels of the Yeast Alcohol Acetyltransferase Genes ATF1, Lg-ATF1, and ATF2 Control the Formation of a Broad Range of Volatile Esters." Applied and Environmental Microbiology 69, no. 9 (September 2003): 5228–37. http://dx.doi.org/10.1128/aem.69.9.5228-5237.2003.
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ABSTRACT Volatile aroma-active esters are responsible for the fruity character of fermented alcoholic beverages such as beer and wine. Esters are produced by fermenting yeast cells in an enzyme-catalyzed intracellular reaction. In order to investigate and compare the roles of the known Saccharomyces cerevisiae alcohol acetyltransferases, Atf1p, Atf2p and Lg-Atf1p, in volatile ester production, the respective genes were either deleted or overexpressed in a laboratory strain and a commercial brewing strain. Subsequently, the ester formation of the transformants was monitored by headspace gas chromatography and gas chromatography combined with mass spectroscopy (GC-MS). Analysis of the fermentation products confirmed that the expression levels of ATF1 and ATF2 greatly affect the production of ethyl acetate and isoamyl acetate. GC-MS analysis revealed that Atf1p and Atf2p are also responsible for the formation of a broad range of less volatile esters, such as propyl acetate, isobutyl acetate, pentyl acetate, hexyl acetate, heptyl acetate, octyl acetate, and phenyl ethyl acetate. With respect to the esters analyzed in this study, Atf2p seemed to play only a minor role compared to Atf1p. The atf1Δ atf2Δ double deletion strain did not form any isoamyl acetate, showing that together, Atf1p and Atf2p are responsible for the total cellular isoamyl alcohol acetyltransferase activity. However, the double deletion strain still produced considerable amounts of certain other esters, such as ethyl acetate (50% of the wild-type strain), propyl acetate (50%), and isobutyl acetate (40%), which provides evidence for the existence of additional, as-yet-unknown ester synthases in the yeast proteome. Interestingly, overexpression of different alleles of ATF1 and ATF2 led to different ester production rates, indicating that differences in the aroma profiles of yeast strains may be partially due to mutations in their ATF genes.
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Wang, Wei, Xiao Hao, Lina Han, Zhe Yan, Wen-Jun Shen, Dachuan Dong, Kathrin Hasbargen, et al. "Tissue-Specific Ablation of ACSL4 Results in Disturbed Steroidogenesis." Endocrinology 160, no. 11 (August 27, 2019): 2517–28. http://dx.doi.org/10.1210/en.2019-00464.
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Abstract ACSL4 is a member of the ACSL family that catalyzes the conversion of long-chain fatty acids to acyl-coenzyme As, which are essential for fatty-acid incorporation and utilization in diverse metabolic pathways, including cholesteryl ester synthesis. Steroidogenic tissues such as the adrenal gland are particularly enriched in cholesteryl esters of long-chain polyunsaturated fatty acids, which constitute an important pool supplying cholesterol for steroid synthesis. The current studies addressed whether ACSL4 is required for normal steroidogenesis. CYP11A1 promoter‒mediated Cre was used to generate steroid tissue‒specific ACSL4 knockout (KO) mice. Results demonstrated that ACSL4 plays an important role in adrenal cholesteryl ester formation, as well as in determining the fatty acyl composition of adrenal cholesteryl esters, with ACSL4 deficiency leading to reductions in cholesteryl ester storage and alterations in cholesteryl ester composition. Statistically significant reductions in corticosterone and testosterone production, but not progesterone production, were observed in vivo, and these deficits were accentuated in ex vivo and in vitro studies of isolated steroid tissues and cells from ACSL4-deficient mice. However, these effects on steroid production appear to be due to reductions in cholesteryl ester stores rather than disturbances in signaling pathways. We conclude that ACSL4 is dispensable for normal steroidogenesis.
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Olusola, Adesanya Ibiyinka. "Esther: Biblical Model for Women Leadership Role in Contemporary Nigeria." MIMBAR PENDIDIKAN 1, no. 1 (March 23, 2016): 77. http://dx.doi.org/10.17509/mimbardik.v1i1.1755.
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<p><strong><em>ABSTRACT</em></strong><strong><em>: </em></strong><em>The paper examined critically the story of Esther in the Bible</em><em>,</em><em> who delivered her nation when they were being threatened with total annihilation</em><em>. </em><em>The patriotism, faith, prayer</em><em>,</em><em> and determination she combined to deliver her nation were examined. With the background story of Esther given, the paper noted that leaders of women’s groups could use Esther as a role model to rescue Nigeria from total collapse</em><em>,</em><em> especially now that the peace of the nation is being threatened by Boko Haram insurgency. To make this more challenging to the women folk, the paper appraised the positive contributions of some women in the pre</em><em>-</em><em>colonial, colonial</em><em>,</em><em> and post</em><em>-</em><em>colonial period</em><em>s</em><em>. The paper observed that women who were appointed to the key administrative and political positions at this period performed creditably. However, the paper observed that some women started off well, but veered off to corruption. It is</em><em>,</em><em> therefore</em><em>,</em><em> noted that the fact that some women did not play their roles correctly does not mean there could</em><em> </em><em>n</em><em>o</em><em>t be a change. It is against this background that the paper recommended Biblical leadership model of Esther</em><em>,</em><em> which </em><em>is a</em><em> model of determination, self</em><em>-</em><em>sacrifice, prayer, humility</em><em>,</em><em> and righteousness. Equally</em><em>,</em><em> women were encouraged to use their positions to </em><em>improve, although</em><em> the</em><em>y are</em><em> the less privileged in the society</em><em>,</em><em> and to always take advantage of any circumstance.</em></p><p><strong><em>K</em></strong><strong><em>EY</em></strong><strong><em> </em></strong><strong><em>WORD</em></strong><em>: </em><em>E</em><em>sther</em><em>,</em><em> women leadership</em><em>,</em><em> role model</em><em>,</em><em> patriotism,</em><em> </em><em>and </em><em>self</em><em>-</em><em>sacrifice.</em><em> </em></p><p><strong><em>ABTRAKSI: “</em></strong><em>Esther: Teladan dalam Alkitab untuk Peran Kepemimpinan Perempuan di Negara Nigeria Kini”. Makalah ini mengkaji secara kritis kisah Ester dalam Alkitab, yang menyelamatkan bangsanya ketika terancam dalam kehancuran total. Patriotisme, iman, doa, dan tekad yang Esther lakukan untuk membebaskan bangsanya itu dikaji dalam penelitian ini. Dengan latar belakang cerita Ester, makalah ini mencatat bahwa pemimpin kelompok perempuan bisa menggunakan Esther sebagai model atau teladan untuk menyelamatkan Nigeria dari kehancuran total, terutama sekarang ini karena perdamaian bangsa sedang terancam oleh pemberontakan Boko Haram. Untuk menjadikan hal ini lebih menantang bagi kaum perempuan, makalah ini menilai kontribusi positif dari beberapa wanita pada zaman pra-kolonial, zaman kolonial, dan zaman pasca-kolonial. Makalah ini mengamati bahwa wanita yang ditunjuk untuk menempati posisi administrasi dan politik penting pada periode ini dapat dipercaya. Namun, makalah ini juga mengamati bahwa beberapa wanita memulainya dengan baik, tetapi kemudian melakukan penyimpangan dalam korupsi. Oleh karena itu, perlu dicatat bahwa fakta beberapa wanita tidak memainkan peran mereka dengan benar tidak pula berarti bahwa perubahan tidak mungkin. Dengan latar belakang ini, makalah merekomendasikan model kepemimpinan Esther dalam Alkitab, yang merupakan teladan dalam keteguhan, pengorbanan diri, doa, kerendahan hati, dan kebenaran. Semua perempuan didorong untuk sama-sama menggunakan posisi mereka agar lebih baik, meskipun mereka adalah orang yang kurang beruntung dalam masyarakat, dan untuk selalu mengambil keuntungan dari setiap keadaan.</em></p><p><strong><em>KATA KUNCI</em></strong><em>: Esther, kepemimpinan wanita, teladan, patriotisme, dan pengorbanan diri.</em></p><p><img src="/public/site/images/wirta/07.adesanya_.ng_.ok_.jpg" alt="" /></p><p><strong><em>About the Author:</em></strong> <strong>Dr. Adesanya Ibiyinka Olusola</strong> is a Lecturer at the Department of Religious Studies, Ekiti State University, Ado-Ekiti, Nigeria. For academic interests, the author is able to be contacted via mobile phone at: +2348133946799 or e-mail at: <a href="mailto:olusolaibiyinka@yahoo.com">olusolaibiyinka@yahoo.com</a></p><p><strong><em>How to cite this article?</em></strong> Olusola, Adesanya Ibiyinka. (2016). “Esther: Biblical Model for Women Leadership Role in Contemporary Nigeria” in <em>MIMBAR PENDIDIKAN</em><em>: </em><em>Jurnal Indonesia untuk Kajian Pendidikan</em>, Vol.1(1) Maret, pp.77-86. Bandung, Indonesia: UPI Press. <strong></strong></p><p><em><strong><em>Chronicle of the article:</em></strong> </em>Accepted (February 11, 2016); Revised (February 21, 2016); and Published (March 11, 2016).<em><br /></em></p>
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Wahlen, Bradley D., Whitney S. Oswald, Lance C. Seefeldt, and Brett M. Barney. "Purification, Characterization, and Potential Bacterial Wax Production Role of an NADPH-Dependent Fatty Aldehyde Reductase from Marinobacter aquaeolei VT8." Applied and Environmental Microbiology 75, no. 9 (March 6, 2009): 2758–64. http://dx.doi.org/10.1128/aem.02578-08.
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ABSTRACT Wax esters, ester-linked fatty acids and long-chain alcohols, are important energy storage compounds in select bacteria. The synthesis of wax esters from fatty acids is proposed to require the action of a four-enzyme pathway. An essential step in the pathway is the reduction of a fatty aldehyde to the corresponding fatty alcohol, although the enzyme responsible for catalyzing this reaction has yet to be identified in bacteria. We report here the purification and characterization of an enzyme from the wax ester-accumulating bacterium Marinobacter aquaeolei VT8, which is a proposed fatty aldehyde reductase in this pathway. The enzyme, a 57-kDa monomer, was expressed in Escherichia coli as a fusion protein with the maltose binding protein on the N terminus and was purified to near homogeneity by using amylose affinity chromatography. The purified enzyme was found to reduce a number of long-chain aldehydes to the corresponding alcohols coupled to the oxidation of NADPH. The highest specific activity was observed for the reduction of decanal (85 nmol decanal reduced/min/mg). Short-chain and aromatic aldehydes were not substrates. The enzyme showed no detectable catalysis of the reverse reaction, the oxidation of decanol by NADP+. The mechanism of the enzyme was probed with several site-specific chemical probes. The possible uses of this enzyme in the production of wax esters are discussed.
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Leibson, P. J., D. E. Midthun, K. P. Windebank, and R. T. Abraham. "Transmembrane signaling during natural killer cell-mediated cytotoxicity. Regulation by protein kinase C activation." Journal of Immunology 145, no. 5 (September 1, 1990): 1498–504. http://dx.doi.org/10.4049/jimmunol.145.5.1498.
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Abstract NK cells can mediate either FcR-dependent cytotoxicity against antibody-coated target cells or direct cytotoxicity against a variety of tumor cells. We used homogeneous, cloned populations of CD16+/CD3- human NK cells to characterize and compare the transmembrane signaling mechanisms used during these alternative forms of cytotoxicity. Cross-linkage of NK cell FcR with anti-FcR (anti-CD16) mAb or direct binding to NK-sensitive tumor targets resulted in a rapid release of inositol phosphates and increases in [Ca2+]i. The receptor-dependent [Ca2+]i increase (as monitored in indo-1 loaded NK cells by flow cytometry) consisted of an initial release of calcium from intracellular stores, followed by a sustained influx of calcium across the plasma membrane. To assess the potential regulatory feedback role of protein kinase C (PKC) activation in these proximal signaling events, NK cells were pretreated with either PKC-activating phorbol esters, nonactivating phorbol ester homologs, or synthetic diacylglycerols. Brief pretreatment with activating phorbol esters rapidly inhibited, in a concentration-dependent manner, both phosphoinositide hydrolysis and increases in [Ca2+]i induced by FcR ligation, whereas pretreatment with an inactive phorbol ester had no effect. This acute inhibitory effect was not explained by FcR down-regulation, which occurred with more prolonged exposure to phorbol esters. In contrast, the phosphoinositide turnover and [Ca2+]i increase in NK cells stimulated with NK-sensitive tumor targets were not affected by prior exposure to PKC-activating phorbol esters. This differential regulatory effect of phorbol ester on proximal signaling was paralleled by a corresponding effect on cytotoxicity, i.e., phorbol ester-induced activation of PKC inhibited FcR-dependent cytotoxicity, but did not alter direct cytotoxicity against NK-sensitive tumor cells. These results indicate that PKC activation can differentially regulate alternative forms of NK cell-mediated cytotoxicity by rapidly and specifically desensitizing the FcR.
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Garg, M. L., A. A. Wierzbicki, A. B. R. Thomson, and M. T. Clandinin. "ω–3 fatty acids increase the arachidonic acid content of liver cholesterol ester and plasma triacylglycerol fractions in the rat." Biochemical Journal 261, no. 1 (July 1, 1989): 11–15. http://dx.doi.org/10.1042/bj2610011.
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Recent studies have demonstrated that dietary fish oils rich in eicosapentaenoic acid (C20:5,omega 3) lower the content of arachidonic acid and its metabolites in plasma and tissue phospholipids. The present study examined the fatty acid composition of cholesterol ester and triacylglycerol fractions from plasma and livers of rats fed diets enriched with saturated fatty acids (beef tallow), alpha-linolenic acid (linseed oil) or eicosapentaenoic acid (fish oil). Feeding diets containing linseed oil or fish oil for 28 days increased arachidonic acid (C20:4,omega 6) levels in the cholesterol ester fraction of liver and in the triacylglycerol fraction of the plasma lipids. Plasma cholesterol esters were depleted of C20:4,omega 6 after feeding of the diet containing either linseed oil or fish oil. The changes in C20:4,omega 6 content cannot be explained by alterations in cholesterol ester or triacylglycerol pools of plasma and liver. These results suggest that the decrease in phospholipid C20:4,omega 6 content generally observed after fish oil consumption may be partly due to a shift of C20:4,omega 6 from phospholipid to the triacylglycerol and/or cholesterol ester pools in the same tissue. Triacylglycerols and cholesterol esters may therefore play a buffering role in the homeostatic maintenance of tissue phospholipid levels of arachidonic acid.
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Badeau, Maija, Veera Vihma, Tomi S. Mikkola, Aila Tiitinen, and Matti J. Tikkanen. "Estradiol Fatty Acid Esters in Adipose Tissue and Serum of Pregnant and Pre- and Postmenopausal Women." Journal of Clinical Endocrinology & Metabolism 92, no. 11 (November 1, 2007): 4327–31. http://dx.doi.org/10.1210/jc.2007-1372.
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Abstract Context: The 17β-estradiol fatty acid esters are hormone derivatives with long-lasting estrogenic effect. They are transported in serum lipoproteins and thought to be sequestered in adipose tissue. Objective: Our objective was to determine the 17β-estradiol fatty acid ester concentrations in serum and adipose tissue in women of various hormonal states. Design: After several chromatographic steps separating esterified from free estradiol, time-resolved fluoroimmunoassay was used as a quantifying tool. Participants: Samples were obtained from pregnant women undergoing cesarean section (n = 13), or premenopausal (n = 8) and postmenopausal women (n = 6) during gynecological surgery. Main Outcome Measures: 17β-Estradiol and 17β-estradiol fatty acid ester concentrations in serum, and visceral and sc adipose tissue were examined. Results: The ratio of esterified to free estradiol in plasma increased with decreasing estradiol level from 0.5% in pregnant, to 15% in premenopausal and 110% in postmenopausal women. Estradiol esters constituted about 10% of the free estradiol present in adipose tissue in pregnancy. In nonpregnant women, most of the adipose tissue estradiol was in esterified form, the median ester to free ratio being elevated to 150–490%. After menopause, the overwhelming majority of estradiol in both free and esterified form was present in adipose tissue. Conclusions: The overall higher ester to free estradiol ratio in adipose tissue than in serum indicates active esterification capacity in adipose tissue. The predominance of esterified and free estradiol in postmenopausal adipose tissue compared with serum suggests in situ production and storage. Whether the estradiol esters have an independent physiological role in adipose tissue remains to be clarified.
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Valmu, L., and C. G. Gahmberg. "Treatment with okadaic acid reveals strong threonine phosphorylation of CD18 after activation of CD11/CD18 leukocyte integrins with phorbol esters or CD3 antibodies." Journal of Immunology 155, no. 3 (August 1, 1995): 1175–83. http://dx.doi.org/10.4049/jimmunol.155.3.1175.
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Abstract The CD11/CD18 leukocyte integrins comprise three heterodimers involved in leukocyte adhesion. CD11/CD18 avidity may be regulated intracellularly, and the CD18 polypeptide has previously been shown to become phosphorylated in leukocytes after phorbol ester stimulation. The importance of phosphorylation in the regulation of CD11/CD18 avidity has, however, remained unclear. We have now activated T cells using phorbol esters, CD3, and CD44 Abs. Both phorbol ester and CD3 treatment activated protein kinase C. CD18 was shown to become more stably phosphorylated after phorbol ester treatment and more transiently so after CD3 stimulation. The phosphorylation was strongly augmented by okadaic acid, a serine/threonine phosphatase inhibitor. While phorbol ester treatment caused phosphorylation mainly on serine, in okadaic acid-pretreated cells, both phorbol ester treatment as well as CD3 stimulation revealed strong threonine phosphorylation. Since earlier mutational studies have demonstrated the functional importance of cytoplasmic threonine residues in CD18, the threonine phosphorylation reported here indicates the role of threonine phosphorylation in the regulation of CD11/CD18 avidity.
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O'Byrne, Sheila M., Yuko Kako, Richard J. Deckelbaum, Inge H. Hansen, Krzysztof Palczewski, Ira J. Goldberg, and William S. Blaner. "Multiple pathways ensure retinoid delivery to milk: studies in genetically modified mice." American Journal of Physiology-Endocrinology and Metabolism 298, no. 4 (April 2010): E862—E870. http://dx.doi.org/10.1152/ajpendo.00491.2009.
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Retinoids are absolutely required for normal growth and development during the postnatal period. We studied the delivery of retinoids to milk, availing of mouse models modified for proteins thought to be essential for this process. Milk retinyl esters were markedly altered in mice lacking the enzyme lecithin:retinol acyltransferase ( Lrat−/−), indicating that this enzyme is normally responsible for the majority of retinyl esters incorporated into milk and not an acyl-CoA dependent enzyme, as proposed in the literature. Unlike wild-type milk, much of the retinoid in Lrat−/− milk is unesterified retinol, not retinyl ester. The composition of the residual retinyl ester present in Lrat−/− milk was altered from predominantly retinyl palmitate and stearate to retinyl oleate and medium chain retinyl esters. This was accompanied by increased palmitate and decreased oleate in Lrat−/− milk triglycerides. In other studies, we investigated the role of retinol-binding protein in retinoid delivery for milk formation. We found that Rbp−/− mice maintain milk retinoid concentrations similar to those in matched wild-type mice. This appears to arise due to greater postprandial delivery of retinoid, a lipoprotein lipase (LPL)-dependent pathway. Importantly, LPL also acts to assure delivery of long-chain fatty acids (LCFA) to milk. The fatty acid transporter CD36 also facilitated LCFA but not retinoid incorporation into milk. Our data show that compensatory pathways for the delivery of retinoids ensure their optimal delivery and that LRAT is the most important enzyme for milk retinyl ester formation.
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Banerjee, Sudheer K., R. Shanker, and Om P. Sachdeva. "Kinetics of Pb(IV) Oxidation of Substituted Methyl Mandelates — A L.F. E. R. Study." Zeitschrift für Naturforschung B 41, no. 4 (April 1, 1986): 467–72. http://dx.doi.org/10.1515/znb-1986-0411.
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Lead tetra acetate (Pb(IV) or LTA) oxidation of the esters X -C6H4-CH(OH)-COOCH3(X = H, m-NO2, p-NO2, m-Cl, p-Cl, p-Br. p-CH3 and p-C2H5) gives corresponding keto esters. The reaction is first order in [Pb(IV)] and second order in [Ester], and is catalysed by pyridine and 2,6-lutidine. The pyridine catalysed reaction is first order each in [Pb(IV)]. [Ester] and [Pyridine]. A kinetic isotope effect is observed in oxidation of methyl m andelate for both uncatalysed reaction (kH/kD = 4.2) and pyridine catalysed reaction (kH/kD = 1.8). Activation param eters for both uncatalysed and pyridine catalysed reactions are evaluated. The results are in accord with Linear Free Energy Relationship (L.F.E.R.) and the reaction constant (ϱ = +0.75) obtained supports proton transfer in the ɑ-C-H bond rupture in the rate limiting step. The role pf pyridine in catalysis, as a ligand or as a base is discussed
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Pieters, M. N., G. R. Castro, D. Schouten, P. Duchateau, J. C. Fruchart, and T. J. C. Van Berkel. "Cholesterol esters selectively delivered in vivo by high-density-lipoprotein subclass LpA-I to rat liver are processed faster into bile acids than are LpA-I/A-II-derived cholesterol esters." Biochemical Journal 292, no. 3 (June 15, 1993): 819–23. http://dx.doi.org/10.1042/bj2920819.
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High-density lipoprotein (HDL) subclass LpA-I has been reported to promote cholesterol efflux from mouse adipose cells in vitro, whereas subclass LpA-I/A-II has no effect. To investigate whether the apolipoprotein composition of HDL plays a role in the selective delivery of cholesterol esters to the liver in vivo, we labelled HDL in its cholesterol ester moiety and separated [3H]cholesterol oleate-labelled HDL into subclasses LpA-I and LpA-I/A-II by immuno-affinity chromatography. Serum decay and liver association of LpA-I and LpA-I/A-II were compared for the apoprotein and cholesterol ester moieties. Both LpA-I and LpA-I/A-II selectively delivered cholesterol esters to the liver with similar kinetics. The kinetics of biliary secretion of processed cholesterol esters, initially associated with LpA-I or LpA-I/A-II, were studied in rats equipped with permanent catheters in bile, duodenum and heart. For both LpA-I and LpA-I/A-II, liver association was coupled to bile acid synthesis, with an increase in secretion rate during the night. During the first night period, the biliary secretion of LpA-I-derived radio-activity was significantly greater than for LpA-I/A-II. The data indicate that with both LpA-I and LpA-I/A-II selective delivery of cholesterol esters from HDL to the liver occurs, but that cholesterol esters delivered by LpA-I are more efficiently coupled to bile acid synthesis.
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Pieters, M. N., D. Schouten, H. F. Bakkeren, B. Esbach, A. Brouwer, D. L. Knook, and T. J. C. van Berkel. "Selective uptake of cholesteryl esters from apolipoprotein-E-free high-density lipoproteins by rat parenchymal cells in vivo is efficiently coupled to bile acid synthesis." Biochemical Journal 280, no. 2 (December 1, 1991): 359–65. http://dx.doi.org/10.1042/bj2800359.
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[3H]Cholesteryl ester-labelled human high-density lipoprotein (HDL) was injected into rats and its decay, intrahepatic cellular distribution and the kinetics of biliary secretion were determined. At 10 min after injection the hepatic uptake of cholesteryl esters from HDL was 3-fold higher as compared with the apolipoprotein. Selective uptake was exerted only by parenchymal cells (5.6-fold more cholesteryl esters than apolipoprotein) and not by liver endothelial or Kupffer cells. The kinetics of biliary secretion of processed cholesteryl esters initially associated with HDL or low-density lipoprotein (LDL) were compared in unrestrained rats, equipped with permanent catheters in bile duct, duodenum and heart. At 72 h after injection of [3H]cholesteryl oleate-labelled HDL, 51.0 +/- 2.5% of the injected dose was recovered as bile acids, which is about twice as high as the secretion of biliary radioactivity after injection of [3H]cholesteryl oleate-labelled LDL. Oestradiol treatment stimulated only liver uptake of LDL cholesteryl esters, and resulted in a 2-fold higher liver uptake than with HDL. However, the rate of radioactive bile acid formation from [3H]cholesteryl oleate-labelled HDL was still more rapid than for LDL. It is concluded that the selective uptake pathway for cholesteryl esters from HDL in parenchymal cells is more efficiently coupled to the formation of bile acids than is the cholesteryl ester uptake from LDL. This efficient coupling may facilitate the role of HDL in reverse cholesterol transport.
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Lenneman, Eric M., Janet M. Ohlert, Nagendra P. Palani, and Brett M. Barney. "Fatty Alcohols for Wax Esters in Marinobacter aquaeolei VT8: Two Optional Routes in the Wax Biosynthesis Pathway." Applied and Environmental Microbiology 79, no. 22 (September 6, 2013): 7055–62. http://dx.doi.org/10.1128/aem.02420-13.
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ABSTRACTThe biosynthesis of wax esters in bacteria is accomplished by a unique pathway that combines a fatty alcohol and a fatty acyl coenzyme A substrate. Previousin vitroenzymatic studies indicated that two different enzymes could be involved in the synthesis of the required fatty alcohol inMarinobacter aquaeoleiVT8. In this study, we demonstrate through a series of gene deletions and transcriptional analysis that either enzyme is capable of fulfilling the role of providing the fatty alcohol required for wax ester biosynthesisin vivo, but evolution has clearly selected one of these, a previously characterized fatty aldehyde reductase, as the preferred enzyme to perform this reaction under typical wax ester-accumulating conditions. These results complement previousin vitrostudies and provide the first glimpse into the role of each enzymein vivoin the native organism.
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Pani, Alessandra, Claudia Norfo, Claudia Abete, Claudia Mulas, Marirosa Putzolu, Sergio Laconi, Christina Doriana Orrù, et al. "Antiprion Activity of Cholesterol Esterification Modulators: a Comparative Study Using Ex Vivo Sheep Fibroblasts and Lymphocytes and Mouse Neuroblastoma Cell Lines." Antimicrobial Agents and Chemotherapy 51, no. 11 (August 20, 2007): 4141–47. http://dx.doi.org/10.1128/aac.00524-07.
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ABSTRACT Our studies on the role of cholesterol homeostasis in the pathogenesis of scrapie revealed abnormal accumulation of cholesterol esters in ex vivo peripheral blood mononuclear cells (PBMCs) and skin fibroblasts from healthy and scrapie-affected sheep carrying a scrapie-susceptible genotype compared to sheep with a resistant genotype. Similar alterations were observed in mouse neuroblastoma N2a cell lines persistently infected with mouse-adapted 22L and RML strains of scrapie that showed up to threefold-higher cholesterol ester levels than parental N2a cells. We now report that proteinase K-resistant prion protein (PrPres)-producing cell populations of subclones from scrapie-infected cell lines were characterized by higher cholesterol ester levels than clone populations not producing PrPres. Treatments with a number of drugs known to interfere with different steps of cholesterol metabolism strongly reduced the accumulation of cholesterol esters in ex vivo PBMCs and skin fibroblasts from scrapie-affected sheep but had significantly less or no effect in their respective scrapie-resistant or uninfected counterparts. In scrapie-infected N2a cells, inhibition of cholesterol esters was associated with selective antiprion activity. Effective antiprion concentrations of cholesterol modulators (50% effective concentration [EC50] range, 1.4 to 40 μM) were comparable to those of antiprion reference compounds (EC50 range, 0.6 to 10 μM). These data confirm our hypothesis that abnormal accumulation of cholesterol esters may represent a biological marker of susceptibility to prion infection/replication and a novel molecular target of potential clinical importance.
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Quadro, Loredana, Leora Hamberger, Max E. Gottesman, Vittorio Colantuoni, Rajasekhar Ramakrishnan, and William S. Blaner. "Transplacental delivery of retinoid: the role of retinol-binding protein and lipoprotein retinyl ester." American Journal of Physiology-Endocrinology and Metabolism 286, no. 5 (May 2004): E844—E851. http://dx.doi.org/10.1152/ajpendo.00556.2003.
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Retinoids are required for normal embryonic development. Both embryonic retinoid deficiency and excess result in congenital malformations. There is little understanding of the physiology underlying retinoid transfer from the maternal circulation to the embryo. We now report studies that explore this process using retinol-binding protein-deficient (RBP−/−) mice and mice that express human RBP on the RBP−/−background. Our studies establish that dietary retinoid, bound to lipoproteins, can serve as an important source for meeting tissue retinoid requirements during embryogenesis. Indeed, retinyl ester concentrations in the circulations of pregnant RBP−/−mice are significantly elevated over those observed in wild-type mice, suggesting that lipoprotein retinyl esters may compensate for the absence of retinol-RBP during pregnancy. We also demonstrate, contrary to earlier proposals, that maternal RBP does not cross the placenta and cannot enter the fetal circulation. Overall, our data indicate that both retinol-RBP and retinyl esters bound to lipoproteins are able to provide sufficient retinoid to the embryo to allow for normal embryonic development.
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Auer, Alexandra, Julia von Blume, Sabine Sturany, Götz von Wichert, Johan Van Lint, Jackie Vandenheede, Guido Adler, and Thomas Seufferlein. "Role of the Regulatory Domain of Protein Kinase D2 in Phorbol Ester Binding, Catalytic Activity, and Nucleocytoplasmic Shuttling." Molecular Biology of the Cell 16, no. 9 (September 2005): 4375–85. http://dx.doi.org/10.1091/mbc.e05-03-0251.
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Protein kinase D2 (PKD2) belongs to the PKD family of serine/threonine kinases that is activated by phorbol esters and G protein-coupled receptors (GPCRs). Its C-terminal regulatory domain comprises two cysteine-rich domains (C1a/C1b) followed by a pleckstrin homology (PH) domain. Here, we examined the role of the regulatory domain in PKD2 phorbol ester binding, catalytic activity, and subcellular localization: The PH domain is a negative regulator of kinase activity. C1a/C1b, in particular C1b, is required for phorbol ester binding and gastrin-stimulated PKD2 activation, but it has no inhibitory effect on the catalytic activity. Gastrin triggers nuclear accumulation of PKD2 in living AGS-B cancer cells. C1a/C1b, not the PH domain, plays a complex role in the regulation of nucleocytoplasmic shuttling: We identified a nuclear localization sequence in the linker region between C1a and C1b and a nuclear export signal in the C1a domain. In conclusion, our results define the critical components of the PKD2 regulatory domain controlling phorbol ester binding, catalytic activity, and nucleocytoplasmic shuttling and reveal marked differences to the regulatory properties of this domain in PKD1. These findings could explain functional differences between PKD isoforms and point to a functional role of PKD2 in the nucleus upon activation by GPCRs.
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Müllner, Heidemarie, and Günther Daum. "Dynamics of neutral lipid storage in yeast." Acta Biochimica Polonica 51, no. 2 (June 30, 2004): 323–47. http://dx.doi.org/10.18388/abp.2004_3574.
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Since energy storage is a basic metabolic process, the synthesis of neutral lipids occurs in all kingdoms of life. The yeast, Saccharomyces cerevisiae, widely accepted as a model eukaryotic cell, contains two classes of neutral lipids, namely steryl esters and triacylglycerols. Triacylglycerols are synthesized through two pathways governed by the acyl-CoA diacylglycerol acyltransferase Dga1p and the phospholipid diacylglycerol acyltransferase Lro1p, respectively. Steryl esters are formed by the two steryl ester synthases Are1p and Are2p, two enzymes with overlapping function which also catalyze triacylglycerol formation, although to a minor extent. Storage of neutral lipids is tightly linked to the biogenesis of so called lipid particles. The role of this compartment in lipid homeostasis and its interplay with other organelles involved in neutral lipid dynamics, especially the endoplasmic reticulum and the plasma membrane, are subject of current investigations. In contrast to neutral lipid formation, mobilization of triacylglycerols and steryl esters in yeast are less characterized at the molecular level. Only recently, the triacylglycerol lipase Tgl3p was identified as the first yeast enzyme of this kind by function. Genes and gene products governing steryl ester mobilization still await identification. Besides biochemical properties of enzymes involved in yeast neutral lipid synthesis and degradation, regulatory aspects of these pathways and cell biological consequences of neutral lipid depletion will be discussed in this minireview.
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Wiest, P. M., S. S. Kunz, and K. R. Miller. "Activation of protein kinase C by phorbol esters disrupts the tegument of Schistosoma mansoni." Parasitology 109, no. 4 (November 1994): 461–68. http://dx.doi.org/10.1017/s0031182000080719.
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SUMMARYThe tegument of the human parasite Schistosoma mansoni is critical for parasite survival within the mammalian host. The role of protein kinase C (PKC), a major effector molecule in the phosphoinositide pathway, in maintaining the structural organization of this syncytial layer was examined in adult worms. Phorbol 12-myristate, 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDB), phorbol esters that activate PKC, induced formation of surface vesicles as determined by light and scanning electron microscopy. Similar results were seen with sn-2-dioctanoyl-glycerol, a synthetic analogue of diacylglycerol. No effect was seen in parasites incubated with 4-a-phorbol ester or a isomers of PMA or PDB, compounds that do not activate PKC. Vesicle formation was reversible in parasites treated with sn-2-dioctanoyl-glycerol but not with phorbol esters. The tegument of male worms was more sensitive to the effect of phorbol esters than females. Transmission electron microscopy revealed vacuolization of the tegument. These data suggest that signal transduction pathways may have a critical role in the maintenance of the structural integrity of the tegument of parasitic helminths.
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Harwood, Seandean Lykke, Nadia Sukusu Nielsen, Kathrine Tejlgård Jensen, Peter Kresten Nielsen, Ida B. Thøgersen, and Jan J. Enghild. "α2-Macroglobulin-like protein 1 can conjugate and inhibit proteases through their hydroxyl groups, because of an enhanced reactivity of its thiol ester." Journal of Biological Chemistry 295, no. 49 (September 25, 2020): 16732–42. http://dx.doi.org/10.1074/jbc.ra120.015694.
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Proteins in the α-macroglobulin (αM) superfamily use thiol esters to form covalent conjugation products upon their proteolytic activation. αM protease inhibitors use theirs to conjugate proteases and preferentially react with primary amines (e.g. on lysine side chains), whereas those of αM complement components C3 and C4B have an increased hydroxyl reactivity that is conveyed by a conserved histidine residue and allows conjugation to cell surface glycans. Human α2-macroglobulin–like protein 1 (A2ML1) is a monomeric protease inhibitor but has the hydroxyl reactivity–conveying histidine residue. Here, we have investigated the role of hydroxyl reactivity in a protease inhibitor by comparing recombinant WT A2ML1 and the A2ML1 H1084N mutant in which this histidine is removed. Both of A2ML1s' thiol esters were reactive toward the amine substrate glycine, but only WT A2ML1 reacted with the hydroxyl substrate glycerol, demonstrating that His-1084 increases the hydroxyl reactivity of A2ML1's thiol ester. Although both A2ML1s conjugated and inhibited thermolysin, His-1084 was required for the conjugation and inhibition of acetylated thermolysin, which lacks primary amines. Using MS, we identified an ester bond formed between a thermolysin serine residue and the A2ML1 thiol ester. These results demonstrate that a histidine-enhanced hydroxyl reactivity can contribute to protease inhibition by an αM protein. His-1084 did not improve A2ML1's protease inhibition at pH 5, indicating that A2ML1's hydroxyl reactivity is not an adaption to its acidic epidermal environment.
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Sampson, S. R., C. Brodie, and S. V. Alboim. "Role of protein kinase C in insulin activation of the Na-K pump in cultured skeletal muscle." American Journal of Physiology-Cell Physiology 266, no. 3 (March 1, 1994): C751—C758. http://dx.doi.org/10.1152/ajpcell.1994.266.3.c751.
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Administration of insulin to preparations of skeletal muscle causes an increase in Na(+)-K+ pump activity within 15-30 min. Although several mechanisms have been proposed, such as promotion of Na+ influx and translocation of pumps from intracellular to membrane sites, the early events involved in this effect remain unknown. We have investigated the possibility that activation of protein kinase C (PKC) may be an initial event in Na(+)-K+ pump activation in primary cultures of rat skeletal muscle. Insulin (80-100 mU/ml) and tumor-promoting phorbol esters (10-100 nM) increased Na(+)-K+ pump activity as determined by measurements of ouabain-suppressible 86Rb uptake, electrogenic pump component of membrane potential, and specific [3H]ouabain binding. These effects were not reduced by treatment of myotubes with amiloride, which blocks Na(+)-H+ exchange, or with tetrodotoxin, which blocks voltage-dependent Na+ channels. Effects of insulin and phorbol esters were not additive, suggestive of a common mechanism. Effects of both phorbol esters and insulin were significantly reduced by staurosporine (50-100 nM) and by downregulation of PKC (by pretreatment of myotubes with phorbol ester for 24 h). The findings suggest that insulin may stimulate Na(+)-K+ pump activity in skeletal muscle by activation of PKC.
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Shariati, S., C. Ebenau-Jehle, A. A. Pourbabaee, H. A. Alikhani, M. Rodriguez-Franco, M. Agne, M. Jacoby, R. Geiger, F. Shariati, and M. Boll. "Degradation of dibutyl phthalate by Paenarthrobacter sp. Shss isolated from Saravan landfill, Hyrcanian Forests, Iran." Biodegradation 33, no. 1 (November 9, 2021): 59–70. http://dx.doi.org/10.1007/s10532-021-09966-7.
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AbstractPhthalic acid esters are predominantly used as plasticizers and are industrially produced on the million ton scale per year. They exhibit endocrine-disrupting, carcinogenic, teratogenic, and mutagenic effects on wildlife and humans. For this reason, biodegradation, the major process of phthalic acid ester elimination from the environment, is of global importance. Here, we studied bacterial phthalic acid ester degradation at Saravan landfill in Hyrcanian Forests, Iran, an active disposal site with 800 tons of solid waste input per day. A di-n-butyl phthalate degrading enrichment culture was established from which Paenarthrobacter sp. strain Shss was isolated. This strain efficiently degraded 1 g L–1 di-n-butyl phthalate within 15 h with a doubling time of 5 h. In addition, dimethyl phthalate, diethyl phthalate, mono butyl phthalate, and phthalic acid where degraded to CO2, whereas diethyl hexyl phthalate did not serve as a substrate. During the biodegradation of di-n-butyl phthalate, mono-n-butyl phthalate was identified in culture supernatants by ultra-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry. In vitro assays identified two cellular esterase activities that converted di-n-butyl phthalate to mono-n-butyl phthalate, and the latter to phthalic acid, respectively. Our findings identified Paenarthrobacter sp. Shss amongst the most efficient phthalic acid esters degrading bacteria known, that possibly plays an important role in di-n-butyl phthalate elimination at a highly phthalic acid esters contaminated landfill.
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Ryu, Jaihyunk, Jae Il Lyu, Dong-Gun Kim, Jung-Min Kim, Yeong Deuk Jo, Si-Yong Kang, Jin-Baek Kim, Joon-Woo Ahn, and Sang Hoon Kim. "Comparative Analysis of Volatile Compounds of Gamma-Irradiated Mutants of Rose (Rosa hybrida)." Plants 9, no. 9 (September 17, 2020): 1221. http://dx.doi.org/10.3390/plants9091221.
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Roses are one of the most important floricultural crops, and their essential oils have long been used for cosmetics and aromatherapy. We investigated the volatile compound compositions of 12 flower-color mutant variants and their original cultivars. Twelve rose mutant genotypes were developed by treatment with 70 Gy of 60Co gamma irradiation of six commercial rose cultivars. Essential oils from the flowers of the 18 genotypes were analyzed by gas chromatography–mass spectrometry. Seventy-seven volatile compounds were detected, which were categorized into six classes: Aliphatic hydrocarbons, aliphatic alcohols, aliphatic ester, aromatic compounds, terpene alcohols, and others. Aliphatic (hydrocarbons, alcohols, and esters) compounds were abundant categories in all rose flowers. The CR-S2 mutant had the highest terpene alcohols and oil content. Three (CR-S1, CR-S3, and CR-S4) mutant genotypes showed higher ester contents than their original cultivar. Nonacosane, 2-methylhexacosane, and 2-methyltricosane were major volatile compounds among all genotypes. Hierarchical cluster analysis (HCA) of the rose genotypes gave four groups according to grouping among the 77 volatile compounds. In addition, the principal component analysis (PCA) model was successfully applied to distinguish most attractive rose lines. These findings will be useful for the selection of rose genotypes with improved volatile compounds.
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Barney, Brett M., Bradley D. Wahlen, EmmaLee Garner, Jiashi Wei, and Lance C. Seefeldt. "Differences in Substrate Specificities of Five Bacterial Wax Ester Synthases." Applied and Environmental Microbiology 78, no. 16 (June 8, 2012): 5734–45. http://dx.doi.org/10.1128/aem.00534-12.
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ABSTRACTWax esters are produced in certain bacteria as a potential carbon and energy storage compound. The final enzyme in the biosynthetic pathway responsible for wax ester production is the bifunctional wax ester synthase/acyl-coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT), which utilizes a range of fatty alcohols and fatty acyl-CoAs to synthesize the corresponding wax ester. We report here the isolation and substrate range characterization for five WS/DGAT enzymes from four different bacteria:Marinobacter aquaeoleiVT8,Acinetobacter baylyi,Rhodococcus jostiiRHA1, andPsychrobacter cryohalolentisK5. The results from kinetic studies of isolated enzymes reveal a differential activity based on the order of substrate addition and reveal subtle differences between the substrate selectivity of the different enzymes. Thesein vitroresults are compared to the wax ester and triacylglyceride product profiles obtained from each organism grown under neutral lipid accumulating conditions, providing potential insights into the role that the WS/DGAT enzyme plays in determining the final wax ester products that are produced under conditions of nutrient stress in each of these bacteria. Further, the analysis revealed that one enzyme in particular fromM. aquaeoleiVT8 showed the greatest potential for future study based on rapid purification and significantly higher activity than was found for the other isolated WS/DGAT enzymes. The results provide a framework to test prospective differences between these enzymes for potential biotechnological applications such as high-value petrochemicals and biofuel production.
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Lai, W. S., T. B. Rogers, and E. E. el-Fakahany. "Protein kinase C is involved in desensitization of muscarinic receptors induced by phorbol esters but not by receptor agonists." Biochemical Journal 267, no. 1 (April 1, 1990): 23–29. http://dx.doi.org/10.1042/bj2670023.
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Preincubation with receptor agonists or phorbol esters desensitized muscarinic-receptor-mediated [3H]cyclic GMP responses in mouse neuroblastoma N1E-115 cells. However, desensitization mediated by phorbol esters was heterologous, whereas that effected by receptor agonist was specific towards the muscarinic receptors. In addition, there was no loss of cell surface muscarinic receptors, as measured by the binding of the hydrophilic ligand [3H]N-methylscopolamine, when cells were treated with phorbol esters, but receptor-agonist-induced desensitization was accompanied by a decrease in cell surface receptor density. We examined the role of protein kinase C (PKC) in the desensitization of muscarinic receptors by employing a kinase inhibitor and by down-regulation of PKC by long-term incubation of cells with phorbol esters. Whereas these manoeuvres had marked effects on phorbol-ester-induced desensitization of muscarinic responses, they did not block agonist-induced down-regulation and desensitization of muscarinic receptors. In addition, when phosphoinositide hydrolysis was suppressed, the muscarinic agonist was still capable of mediating receptor sequestration and desensitization. These results suggest that the mechanisms for regulating muscarinic receptor sensitivity could be both PKC-dependent and PKC-independent, being mediated by phorbol esters and receptor agonists respectively.
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Tall, A., E. Granot, R. Brocia, I. Tabas, C. Hesler, K. Williams, and M. Denke. "Accelerated transfer of cholesteryl esters in dyslipidemic plasma. Role of cholesteryl ester transfer protein." Journal of Clinical Investigation 79, no. 4 (April 1, 1987): 1217–25. http://dx.doi.org/10.1172/jci112940.
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Liu, Cuibo, Zhongxin Chen, Huan Yan, Shibo Xi, Kah Meng Yam, Jiajian Gao, Yonghua Du, et al. "Expedient synthesis of E-hydrazone esters and 1H-indazole scaffolds through heterogeneous single-atom platinum catalysis." Science Advances 5, no. 12 (December 2019): eaay1537. http://dx.doi.org/10.1126/sciadv.aay1537.
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Unprotected E-hydrazone esters are prized building blocks for the preparation of 1H-indazoles and countless other N-containing biologically active molecules. Despite previous advances, efficient and stereoselective synthesis of these compounds remains nontrivial. Here, we show that Pt single atoms anchored on defect-rich CeO2 nanorods (Pt1/CeO2), in conjunction with the alcoholysis of ammonia borane, promotes exceptionally E-selective hydrogenation of α-diazoesters to afford a wide assortment of N-H hydrazone esters with an overall turnover frequency of up to 566 hours−1 upon reaction completion. The α-diazoester substrates could be generated in situ from readily available carboxylic esters in one-pot hydrogenation reaction. Utility is demonstrated through concise, scalable synthesis of 1H-indazole–derived pharmaceuticals and their 15N-labeled analogs. The present protocol highlights a key mechanistic nuance wherein simultaneous coordination of a Pt site with the diazo N═N and ester carbonyl motifs plays a central role in controlling stereoselectivity, which is supported by density functional theory calculations.
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Mouzat, Kevin, Magali Prod'Homme, David H. Volle, Benoit Sion, Pierre Déchelotte, Karine Gauthier, Jean-Marc Vanacker, and Jean-Marc A. Lobaccaro. "Oxysterol Nuclear Receptor LXRβ Regulates Cholesterol Homeostasis and Contractile Function in Mouse Uterus." Journal of Biological Chemistry 282, no. 7 (December 13, 2006): 4693–701. http://dx.doi.org/10.1074/jbc.m606718200.
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The uterus is an organ where lipid distribution plays a critical role for its function. Here we show that nuclear receptor for oxysterols LXRβ prevents accumulation of cholesteryl esters in mouse myometrium by controlling expression of genes involved in cholesterol efflux and storage (abca1 and abcg1). Upon treatment with an LXR agonist that mimics activation by oxysterols, expression of these target genes was increased in wild-type mice, whereas under basal conditions, lxrα;β-/- mice exhibited a marked decrease in abcg1 accumulation. This change resulted in a phenotype of cholesteryl ester accumulation. Besides, a defect of contractile activity induced by oxytocin or PGF2α was observed in mice lacking LXRβ. These results imply that LXRβ provides a safety valve to limit cholesteryl ester levels as a basal protective mechanism in the uterus against cholesterol accumulation and is necessary for a correct induction of contractions.
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Linke, M. J., F. M. Burton, D. T. Fiedeldey, and W. R. Rice. "Surfactant phospholipid secretion from rat alveolar type II cells: possible role of PKC isozymes." American Journal of Physiology-Lung Cellular and Molecular Physiology 272, no. 2 (February 1, 1997): L171—L177. http://dx.doi.org/10.1152/ajplung.1997.272.2.l171.
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Protein kinase C (PKC) plays an integral role in control of many type II cell functions, including regulation of surfactant phospholipid secretion. To determine which isozymes of PKC may regulate type II cell functions, we identified those PKC isozymes activated in type II cells in association with surfactant phospholipid secretion after phorbol ester treatment. Transcripts encoding PKC-alpha, -beta, -delta, -epsilon, -eta, and -zeta were detected in type II cells by reverse transcriptase-polymerase chain reaction, whereas PKC-alpha, -beta, -delta, -eta, and -zeta were detected in type II cells by immunoblotting. PKC-alpha and -beta were only present in the cytosol in unstimulated type II cells, whereas PKC isozymes delta, eta, and zeta were found in cytosol and membrane fractions in unstimulated type II cells. 12-O-tetradecanoylphorbol-13-acetate stimulated surfactant secretion and activated PKC-alpha, -beta, -delta, and -eta isozymes in a dose-dependent manner. The inactive analogue 4alpha-phorbol 12,13-didecanoate neither activated PKC isozymes nor stimulated surfactant phospholipid secretion. PKC-zeta was not activated by any of the phorbol esters. PKC isozymes alpha, beta, delta, and eta are present in purified type II epithelial cells and are activated in a dose-dependent manner in alveolar type II cells in association with surfactant phospholipid secretion after phorbol ester treatment.
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Kovářová, Anna, Svatopluk Světlík, Václav Kozmík, Jiří Svoboda, Vladimíra Novotná, Damian Pociecha, Ewa Gorecka, and Natalia Podoliak. "Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core." Beilstein Journal of Organic Chemistry 10 (April 7, 2014): 794–807. http://dx.doi.org/10.3762/bjoc.10.75.
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Bent-shaped mesogens possessing a biphenyl as a central core have been synthesized and the role of the terminal chain and the orientation of the ester as a linkage group have been investigated. For the studied molecular core we have established that both parameters play an important role for the mesomorphic properties. The polyfluoroalkyl terminal chain supports the formation of mesophases, and the introduction of a chiral lactate terminal chain destabilizes mesophases for the first type of mutual orientation of ester groups, attached to the central core. On the contrary, for the opposite orientation of esters, the terminal chain has no effect on the mesomorphic properties, and columnar phases have been found for all compounds. A unique phase sequence has been found for the mesogen with the fluorinated chain. A generalized tilted smectics, SmCG, have been observed in a temperature interval between two different lamellar SmCP phases and characterized by X-ray and dielectric measurements. The dielectric spectroscopy data are unique and presented for the first time in the SmCG phase providing new information about the molecular dynamics.
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Jeon, Jeong Ho, Soo-Jin Kim, Hyun Sook Lee, Sun-Shin Cha, Jung Hun Lee, Sang-Hong Yoon, Bon-Sung Koo, et al. "Novel Metagenome-Derived Carboxylesterase That Hydrolyzes β-Lactam Antibiotics." Applied and Environmental Microbiology 77, no. 21 (September 9, 2011): 7830–36. http://dx.doi.org/10.1128/aem.05363-11.
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ABSTRACTIt has been proposed that family VIII carboxylesterases and class C β-lactamases are phylogenetically related; however, none of carboxylesterases has been reported to hydrolyze β-lactam antibiotics except nitrocefin, a nonclinical chromogenic substrate. Here, we describe the first example of a novel carboxylesterase derived from a metagenome that is able to cleave the amide bond of various β-lactam substrates and the ester bond ofp-nitrophenyl esters. A clone with lipolytic activity was selected by functional screening of a metagenomic library using tributyrin agar plates. The sequence analysis of the clone revealed the presence of an open reading frame (estU1) encoding a polypeptide of 426 amino acids, retaining an S-X-X-K motif that is conserved in class C β-lactamases and family VIII carboxylesterases. The gene was overexpressed inEscherichia coli, and the purified recombinant protein (EstU1) was further characterized. EstU1 showed esterase activity toward various chromogenicp-nitrophenyl esters. In addition, it exhibited hydrolytic activity toward nitrocefin, leading us to investigate whether EstU1 could hydrolyze β-lactam antibiotics. EstU1 was able to hydrolyze first-generation β-lactam antibiotics, such as cephalosporins, cephaloridine, cephalothin, and cefazolin. In a kinetic study, EstU1 showed a similar range of substrate affinities for bothp-nitrophenyl butyrate and first-generation cephalosporins while the turnover efficiency for the latter was much lower. Furthermore, site-directed mutagenesis studies revealed that the catalytic triad of EstU1 plays a crucial role in hydrolyzing both ester bonds ofp-nitrophenyl esters and amide bonds of the β-lactam ring of antibiotics, implicating the predicted catalytic triad of EstU1 in both activities.
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Gryvul, T. M., Ye M. Veres, and Ye M. Makukh. "ВПЛИВ ПРОДУКТІВ ОКИСНЕННЯ ЕСТЕРІВ ХОЛЕСТЕРОЛУ НА РОЗВИТОК АТЕРОСКЛЕРОЗУ." Scientific Messenger of LNU of Veterinary Medicine and Biotechnology 18, no. 3(70) (August 11, 2016): 49–57. http://dx.doi.org/10.15421/nvlvet7012.
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Products of per oxide lipid oxidation are produced in the place of increased oxidative stress and their accumulation leads to aterotic damage. Most of the investigations are still devoted to formation and oxidized lipid metabolism, but the data on their biological activity and possible pathophysiological functions are not many. In this review it was done an attempt to analyze the mechanisms of formation, metabolic activity and by transforming the cholesterol ester, which contain the unsaturated fatty acids, that may oxidize to form peroxides. The last are able to be restored to appropriate alcohols, which can be oxidized to biologically active aldehydes, which make a significant contribution to the development of progressive atherosclerotic lesions.The most cholesterol esters are as a part of ß – lipoproteins, localized in the hydrophobic core and in doing so are able to be oxidized hydro peroxides faster than the outer layer of phospholipids. Most of aldehydes, which are formed at per ester oxidation – these are nine–, eight– and five carbon compounds. Because of cholesterol esters in ß – lipoprotein were formed mainly by linoleic acid, therefore its level was reliable test of per oxidation degree of these esters.The analysis of stereoisomers of oxidized lipids, which were marked from atherogenic plaques, witnessed a significant contribution of the enzyme lipooxi genesis in oxidative modification of cholesterol esters. Selenium containing enzymes play an important role in the metabolism of cholesterol hydroxides esters, in particular: glutathionereductase and tioredoxinereductase. It was also obtained the convincing data on the participation of aldosereductase in these processes.Esther of cholesterol inhibit the mitotic activity of growth factor of atherogenic plaques, fibroblast growth factor and the ß1– antiproliferative activity of transforming growth factor.Hence, oxidative modification of lipids in general, oxidized of cholesterol esters and in particular, is one of the causes of progressive development of atherosclerotic damages, Although metabolic pathway of lipoprotein particles to the atherosclerotic plaque is search enough.
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Greaves, Martin Robert, and Evelyn Zaugg Hoozemans. "Improving ester hydrolytic stability using triblock polyalkylene glycols." Industrial Lubrication and Tribology 70, no. 2 (March 12, 2018): 418–22. http://dx.doi.org/10.1108/ilt-09-2017-0272.
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Purpose This paper aims to examine the role of different polyalkylene glycol architectures in improving the hydrolytic stability of natural and synthetic esters. Design/methodology/approach Hydrolytic stability measurements were conducted using a modified ASTM D2619 test method in which several polyalkylene glycol chemistries were examined at concentrations of up to 10 per cent in a selection of esters. Findings The inclusion of triblock copolymers derived from ethylene oxide (EO) and 1,2-propylene oxide (PO) and with an EO content of about 30 per cent produced significant improvements in the hydrolytic stability of natural and synthetic esters. Stability improved with increased concentration of the triblock. Research limitations/implications The study did not evaluate the vast array of polyalkylene glycol structures that can be derived from other higher alkylene oxides. Practical implications Improving the hydrolytic stability of esters can offer the possibility of creating longer life environmentally acceptable lubricants (EALs). Social implications This discovery should allow longer life EALs to be designed thereby using less raw materials over a determined period. It may also allow more replacement of conventional hydrocarbon lubricants. Originality/value Triblock copolymers are rarely used in lubricants. Their use as components of ester-based EALs is new.
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Zhao, Bin, Ramesh Natarajan, and Shobha Ghosh. "Human liver cholesteryl ester hydrolase: cloning, molecular characterization, and role in cellular cholesterol homeostasis." Physiological Genomics 23, no. 3 (November 17, 2005): 304–10. http://dx.doi.org/10.1152/physiolgenomics.00187.2005.
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The liver regulates cholesterol homeostasis and eliminates excess cholesterol as bile acids or biliary cholesterol. Free cholesterol for bile acid synthesis or biliary secretion is obtained by the hydrolysis of stored cholesteryl esters or from cholesteryl esters taken up by the liver from high-density lipoproteins via a selective uptake pathway. The present study was undertaken to characterize the enzyme catalyzing this reaction, namely, cholesterol ester hydrolase (CEH) from the human liver, and demonstrate its role in regulating bile acid synthesis. Two cDNAs were isolated from the human liver that differed only in the presence of an additional alanine at position 18 in one of the clones. Transient transfection of COS-7 cells with a eukaryotic expression vector containing either of these two cDNAs resulted in significant increase in the hydrolysis of cholesteryl esters, authenticating these clones as human liver CEH. CEH mRNA and protein expression in human hepatocytes were demonstrated by real-time PCR and Western blot analyses, respectively, confirming the location of this enzyme in the cell type involved in hepatic cholesterol homeostasis. Overexpression of these CEH clones in human hepatocytes resulted in significant increase in bile acid synthesis, demonstrating a role for liver CEH in modulating bile acid synthesis. This CEH gene mapped on human chromosome 16, and the two clones represent two different transcript variants resulting from splice shifts at exon 1. In conclusion, these data identify that human liver CEH was expressed in hepatocytes, where it potentially regulates the synthesis of bile acids and thus the removal of cholesterol from the body.
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Ahmed, S., R. Kozma, J. Lee, C. Monfries, N. Harden, and L. Lim. "The cysteine-rich domain of human proteins, neuronal chimaerin, protein kinase C and diacylglycerol kinase binds zinc. Evidence for the involvement of a zinc-dependent structure in phorbol ester binding." Biochemical Journal 280, no. 1 (November 15, 1991): 233–41. http://dx.doi.org/10.1042/bj2800233.
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Diacylglycerol (DG) and its analogue phorbol 12-myristate 13-acetate (PMA) activate the ubiquitous phospholipid/Ca2(+)-dependent protein kinase, protein kinase C (PKC), and cause it to become tightly associated with membranes. DG is produced transiently as it is rapidly metabolized by DG kinase (DGK) to phosphatidic acid. Phorbol esters such as PMA are not metabolized and induced a prolonged membrane association of PKC. Until recently, PKC was the only known phorbol ester receptor. We have shown that a novel brain-specific cDNA, neuronal chimaerin (NC), expressed in Escherichia coli, binds phorbol ester with high affinity, stereospecificity and a phospholipid requirement [Ahmed, Kozma, Monfries, Hall, Lim, Smith & Lim (1990) Biochem. J. 272, 767-773]. The proteins NC, PKC and DGK possess a cysteine-rich domain with the motif HX11/12CX2CXnCX2CX4HX2CX6/7C (where n varies between 12 and 14). The partial motif, CX2CX13CX2C, is present in a number of transcription factors including the steroid hormone receptors and the yeast protein, GAL4, in which zinc plays a structural role of co-ordinating cysteine residues and is essential for DNA binding (protein-nucleic acid interactions). The cysteine-rich domain of NC and PKC is required for phospholipid-dependent phorbol is required for phospholipid-dependent phorbol ester binding, suggesting an involvement of this domain in protein-lipid interactions. We have expressed recombinant NC, PKC and DGK glutathione S-transferase and TrpE fusion proteins in E. coli to investigate the relationship between the cysteine-rich motif, HX11/12CX2CX10-14CX2CX4HX2CX6/7C, zinc and phorbol ester binding. The cysteine-rich domain of NC, PKC and DGK bound 65Zn2+ but only NC and PKC bound [3H]phorbol 12,13-dibutyrate. When NC and PKC were subjected to treatments known to remove metal ions from GAL4 and the human glucocorticoid receptor, phorbol ester binding was inhibited. These data provide evidence for the role of a zinc-dependent structure in phorbol ester binding.
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Sholihat, Suvianti, Agus Abdul Rahman, Deden Sudirman, and Nur’aini Azizah. "The Role of Agreeableness and Self-esteem on Fear of Missing Out." International Journal of Psychosocial Rehabilitation 24, no. 1 (January 20, 2020): 1518–25. http://dx.doi.org/10.37200/ijpr/v24i1/pr200249.
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Singh, Dharvinder. "Parental Attachment and Psychological Wellbeing in Adolescents: Mediating Role of Self-esteem." Indian Journal of Youth & Adolescent Health 08, no. 01 (March 29, 2021): 13–17. http://dx.doi.org/10.24321/2349.2880.202103.
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Introduction: Adolescence is amongst the most rapid stage of human development. It is the period to create knowledge and skills, learn to mange emotions, obtain attributes and capacities and relationships with parents and peers. All these aspects are important for enjoying these years and assuming the roles of adults. The purpose of the study was to examine the relationship between parental attachment, self-esteem and psychological wellbeing of adolescents. Methods: The participants were 292 adolescents with age ranging from 13 to 18 years. Inventory for parent and peer attachment (IPPA) by Armsden and Greenberg self-esteem scale by Rosenberg and psychological wellbeing scale by Ryff were used to measure the parental attachment, self-esteem, and psychological wellbeing in adolescents. Result: Results indicated that the the correlation value of parental attachment and psychological wellbeing was found be 0.306. The value of correlation value for self-esteem and psychological wellbeing was found to be 0.342. Conclusion: Significant positive relationship was found between parental attachment, self-esteem, and psychological wellbeing. The mediation analysis has shown that self-esteem partially mediates the relationship between parental attachment and psychological wellbeing among adolescents.
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Fedevych, Eugeniy, Oleh Datsko, and Oleh Fedevych. "The Role of Oxides in Oxidation of Allyl Alcohol and its Esters." Chemistry & Chemical Technology 13, no. 1 (March 5, 2019): 46–51. http://dx.doi.org/10.23939/chcht13.01.046.
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Kalayoglu, Murat V., and Gerald I. Byrne. "A Chlamydia pneumoniae Component That Induces Macrophage Foam Cell Formation Is Chlamydial Lipopolysaccharide." Infection and Immunity 66, no. 11 (November 1, 1998): 5067–72. http://dx.doi.org/10.1128/iai.66.11.5067-5072.1998.
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ABSTRACT Chlamydia pneumoniae infection is associated with atherosclerotic heart and vessel disease, but a causal relationship between this pathogen and the disease process has not been established. Recently, it was reported that C. pneumoniae induces human macrophage foam cell formation, a key event in early atheroma development, suggesting a role for the organism in atherogenesis. This study further examines C. pneumoniae-induced foam cell formation in the murine macrophage cell line RAW-264.7. Infected RAW cells accumulated cholesteryl esters when cultured in the presence of low-density lipoprotein in a manner similar to that described for human macrophages. Exposure of C. pneumoniae elementary bodies to periodate, but not elevated temperatures, inhibited cholesteryl ester accumulation, suggesting a role for chlamydial lipopolysaccharide (cLPS) in macrophage foam cell formation. Purified cLPS was found to be sufficient to induce cholesteryl ester accumulation and foam cell formation. Furthermore, the LPS antagonist lipid X inhibited C. pneumoniae and cLPS-induced lipid uptake. These data indicate that cLPS is a C. pneumoniae component that induces macrophage foam cell formation and suggest that infected macrophages chronically exposed to cLPS may accumulate excess cholesterol to contribute to atheroma development.