This study was carried out to determine the characteristics of common carp surimi. In Australia, common carp (Cyprinus carpio) is an environmental pest, strongly coloured (dark-muscle fish), large (2-3 kg), low cost (AUD 2.5/kg) and not highly valued as it is every where else. Surimi could add value to carp, but the colour would have to be modified as surimi manufacturers prefer white coloured flesh. So, firstly the efficiency of Hydrogen peroxide (H2O2; 1-3% v/v) solution at alkaline side of pH (7.0-11.5) on whitening of light fillets of common carp was examined. The whiteness (L*-3b*) of surimi produced from treated (3% H2O2, pH 8.2) common carp light fillets was significantly (p less than 0.05) greater than that of threadfin bream surimi and was not significantly different to that of Alaska pollock. Based on a temperature sweep test, a similar pattern in G of tested surimi was observed which started at ca. 47?C and was completed at ca. 73-74?C. However, thread fin bream kamaboko showed better texture profile characteristics (hardness and gel strength) than that of the other kamaboko tested. To improve the quality of common carp surimi and kamaboko, alternative methods were applied such as modified conventional method (MCM), alkaline-aided method (AAM) and pH modified method (PMM) and the resultant surimi and kamaboko were compared with those produced by the traditional method (TM). In MCM each washing cycle was followed by a centrifugation step for a more effective dewatering and removal of sarcoplasmic proteins (Sp-P). Kamaboko prepared from MCM was whiter and had significantly (p less than 0.05) improved textural characteristics (hardness and gel strength) than that from TM, AAM and PMM. Furthermore, SEM of surimi and kamaboko showed higher number of polygonal structure/mm2 in the gel matrix of MCM kamaboko, as a result of more cross-linking of the myofibrillar proteins, than that recorded for TM, AAM and PMM samples tested. Finally, this study examined the effect of adding common carp sarcoplasmic proteins (Sp-P) on the gel characteristics of threadfin bream surimi and kamaboko. Based on the temperature sweep test, the depths of the valley in the G thermograph of the gels decreased as the concentration of added Sp-P increased from 5% to 35%. Storage modulus (G) of the gels showed greater elasticity in the samples with added Sp-P compared with the control samples without added Sp-P. Furthermore, the breaking force and breaking distance and consequently gel strength of the resultant kamaboko were improved, significantly (p less than 0.05) with added Sp-P. Thus, added Sp-P did not interfere with the gelling of myofibrillar proteins during sol-gel transition phase and was associated with textural quality enhancement for the resultant kamaboko. However, the addition of freeze-dried Sp-P from the dark muscle of the carp decreased the whiteness of the resultant surimi. Furthermore, the gel strength could not be associated with either the number of polygonal structures/mm2 or the area of the polygonal structures.

Heart failure represents an important cause of death in Western Countries. The pathophysiology of heart failure is mainly associated with abnormalities in intracellular calcium control. We previously showed that Egr-1 negatively regulates expression of sodium-calcium exchanger (NCX) in vivo and in vitro. Here we tested the hypothesis that Egr-1 regulates expression of calcium storage proteins in the sarco-endoplasmic reticulum (SER), calsequestrin (CSQ) and/or ER, calreticulin (CRT) directly or indirectly via Egr-1:NFAT (nuclear factor of activated T-cells) formation. Secondarily, we hypothesized that this will reduce calcium mobilization. We found that undifferentiated 1293F cells, overexpressing Egr-1, have reduced CSQ compared to control H9c2 cells. We demonstrated that Egr-1 negatively regulates CSQ but not CRT expression. The Egr-1 mediated decrease in CSQ is linked to decreased calcium availability. Repression is by a novel NAB-independent (NGFI-A binding protein) activity localized to a.a. region 1-307. We conclude that Egr-1-mediated reductions in calcium storage protein expression alter calcium availability for cardiac contraction/relaxation.

Thesis (Ph. D. in Physics)--Vanderbilt University, May 2006. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--University of Delaware, 2005. / Principal faculty advisor: Norman J. Karin, Dept. of Biological Sciences. Includes bibliographical references.

Orientadores: José Wilson Magalhães Bassani, Rosana Almada Bassani / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-19T11:34:49Z (GMT). No. of bitstreams: 1 Monteiro_MarinaCarneiro_M.pdf: 5677929 bytes, checksum: 5c42afe705a43b66a4505a6ecded7b7c (MD5) Previous issue date: 2011 / Resumo: A fração do conteúdo de Ca2+ do retículo sarcoplasmático (RS) liberada a cada contração (Fractional Release - FR) em miócitos cardíacos é regulada pela corrente de entrada de Ca2+ através da membrana celular pelos canais de Ca2+ tipo-L (ICa,L) e pelo conteúdo de Ca2+ do RS ([Ca2+]RS). Em trabalho anterior foi desenvolvido, no nosso laboratório, um modelo experimental denominado de modelo do RS funcionalmente isolado (MRSFI). Neste modelo, cardiomiócitos são perfundidos em solução sem Na+ e sem Ca2+, o que torna as suas membranas eletricamente inexcitáveis e inibe o transporte do íon pelo trocador Na+/Ca2+. As variações (transientes) da concentração intracelular de Ca2+ ([Ca2+]i) medidas com o indicador fluorescente Fluo-3 AM (5 ?M, 20 min, 24ºC) são evocadas por aplicação de pulsos rápidos (100 ms) de cafeína (10 mM). No presente trabalho, o MRSFI foi usado para estudo da relação entre FR e [Ca2+]RS na ausência do gatilho fisiológico (ICa,L) para liberação reticular de Ca2.... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The fraction of the sarcoplasmic reticulum (SR) Ca2+ content released at a twitch (Fractional Release - FR) in cardiac myocytes is regulated by the transmembrane inward Ca2+ current through the L-type Ca2+ channel (ICa,L) and by the SR Ca2+ content ([Ca2+]SR). In the experimental model of the functionally isolated SR model (FISRM), previously developed in this laboratory, cardiomyocytes are perfused with Na+, Ca2+-free solution, which makes the cells electrically unexcitable and thermodynamically inhibits the sarcolemmal Na+/Ca2+ exchanger. Variations in the intracellular Ca2+ concentration ([Ca2+]i) was measured with the Ca2+ indicator fluo-3 and Ca2+ transients due to SR release are evoked by pulse-like (100 ms duration) application of 10 mM caffeine. In the present work, the FISRM was used to study the relationship between FR and [Ca2+]SR in the absence of ICa,L, the physiological trigger for the release of Ca2+ from the SR.... Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Engenharia Biomedica / Mestre em Engenharia Elétrica

The sarcoplasmic reticulum is an internal membrane system that controls the Ca²⁺ concentration inside muscle cells, and hence the contractile state of both skeletal and cardiac muscle. A key protein that that regulates the Ca²⁺ concentration in this membrane is known as the calcium release channel (CRC). The effects on Ca²⁺ dependent activation is of major importance in the study of CRC since other channel modifiers cannot effect the channel in the absence of Ca²⁺, or they require Ca²⁺ for maximum results. In this study of the high-affinity Ca²⁺ binding site, expected increases in total binding and shifts in the sensitivity of the channel to Ca²⁺ were observed when the pH increased or the solution redox status became more oxidative. Ranolazine, a drug used for treating Angina Pectoris (chest pain), desensitized the cardiac CRC activation but had no effect on the skeletal CRC. This selective desensitization may be the cause of Ranolazine's beneficial therapeutic effects. Both Ranolazine, and homocystein thiolactone (HCTL), a naturally occurring derivative of homocysteine, alters Ca²⁺ dependent activation by calcium without changing the number of channels found in the open state. Surprisingly the effect of HCTL was observed only in a reduced redox potential which leads to speculation that the formation of an alpha-carbon radical by HCTL on the cardiac CRC only occurs if select thiols are in a reduced state.

The purpose of this study is the characterization of the membrane-water interfaces of both sarcoplasmic reticulum membrane (SR) and charged lipid bilayers under varied properties of the surrounding aqueous solution. In this work we studied the electrokinetic properties of liposomes and SR vesicles as well as the interaction of lipophilic ions with these membranes. The study of electrokinetic properties is based on the measurements of electrophoretic mobility of SR membrane vesicles and PC/PG liposomes. Electrophoretic mobility of SR vesicles was measured as a function of ionic strength for six pH values (pH 4.0, 4.7, 5.0, 6.0, 7.5, and 9.0). Electrophoretic mobility of single-layered and multi-layered PC/PG liposomes was measured at neutral pH as a function of ionic strength. For interpretation of electrophoretic mobility studies, SR vesicles (at pH 4, 7, and 9) and multi-layered and single-layered liposome sizes were determined using photoelectron microscopy. The study of the interaction of lipophilic ions with these membranes is based on (1) measurements of their partition coefficients described in terms of an ion partition model based on the Langmuir adsorption model and (2) electrophoretic mobility measurements of SR vesicles and PC liposomes in suspension with varied concentration of lipophilic ions. SR-water and PC-water partition coefficients were measured as a function of concentration for two anions tetraphenylborate (TePB-) and pentabromophenol (PBP-) and two cations (Imipramine+, and Clomipramine+). The anions belong to a class of pesticides and the cations are drugs once prescribed as anti-depressants. Partition into the SR membrane was shown to be significantly greater for all lipophilic ions except TePB-, which only showed this effect at the higher lipophilic ion range of the data. The PC-water partition coefficient was also measured for TePP+. Since the lipid bilayer of SR is not significantly different than that of PC liposomes, we believe the differences in partition are due to excess lipophilic ions being absorbed to the proteins of SR. The electrokinetics of charged PCPG liposomes, and PC liposomes with absorbed lipophilic ions could be understood in terms of the charge being located below their surface and screened by counter-ions inside the polar head-group region. We call this model the "permeable surface model". The assumptions of this model are that (1) the charge exists on a plane at a depth, d, below the surface of the liposome within the lipid head-group region and (2) small ions (Na+, K+, Cl-) are able to penetrate the lipid head-group region with a molar membrane-water partition coefficient of 0.4. Using this model we were able to obtain the depth of sorption of lipophilic ions in PC liposomes. We found values of 0.13 nm for TePB-, 0.5 nm for PBP-, 0.12 nm for Imipramine+, 0.17 nm for Clomipramine and 0.25 nm for TePP+. The depth of lipophilic ions in PC is a valuable quantity for the study of the effect of lipophilic ions on membrane function. For PCPG mobility we found the charged plane due to PG lipids was 0.2 nm for single-layered liposomes and 0.1 nm for multi-layered liposomes. This is consistent with the relative size of PC and PG head groups The dependence of SR mobility on pH was found to be directly correlated with the total charge of the A, P, and N domains of the Ca2+-ATPase as determined by the amino acid residues and their corresponding pKa values in water. We found that detached charged plane model, a new model developed in our group, could be fit to the mobility of SR as a function of ionic strength while other soft particle models failed. The assumptions of this model are that (1) the friction caused by protruding proteins on the surface of SR can be represented by a homogeneous retardation layer of thickness D and softness parameter λRL, and (2) the charge of the APN domain can be represented as a plane of charge embedded in the retardation layer at a distance s from the membrane surface. The best-fit values for λRL, and s were not consistent for different pH value studies. The detached charged plane model was unable to predict the mobility of SR vesicles in the presence of lipophilic ions if we assumed that the lipophilic ions were sorbing to the detached charged plane that represents the native charge of the APN domains of SR. At high lipophilic ion concentration the experimental mobilities consistently were greater in magnitude than the values predicted by the model. We concluded that there is significant absorption of lipophilic ions to the proteins in SR membrane, and that the lipophilic ion sorption sites are not the same as the detached plane of charge that represents the native charge of the APN domain.

京都大学 / 0048 / 新制・課程博士 / 博士(薬科学) / 甲第20059号 / 薬科博第66号 / 新制||薬科||8(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 竹島 浩, 教授 中山 和久, 教授 根岸 学 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

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