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The liver harvested from a donor must be preserved and transported to a suitable recipient immediately for a successful liver transplantation. In this process, the preservation period is the most critical, since it is the longest and most tissue damage occurs during this period due to the reduced blood supply to the harvested liver and the change in its temperature. We investigate the effect of preservation period on the dynamic material properties of bovine liver using a viscoelastic model derived from both impact and ramp and hold experiments. First, we measure the storage and loss moduli of bovine liver as a function of excitation frequency using an impact hammer. Second, its time-dependent relaxation modulus is measured separately through ramp and hold experiments performed by a compression device. Third, a Maxwell solid model that successfully imitates the frequency- and time-dependent dynamic responses of bovine liver is developed to estimate the optimum viscoelastic material coefficients by minimizing the error between the experimental data and the corresponding values generated by the model. Finally, the variation in the viscoelastic material coefficients of bovine liver are investigated as a function of preservation period for the liver samples tested 1 h, 2 h, 4 h, 8 h, 12 h, 24 h, 36 h, and 48 h after harvesting. The results of our experiments performed with three animals show that the liver tissue becomes stiffer and more viscous as it spends more time in the preservation cycle. 相似文献
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In this study, a major cellulase, namely endoglucanase 1 (EGI) from Trichoderma reesei was mutated by the introduction of four different lysine and glycine rich loops to create a hotspot for directed crosslinking of EGI away from the active site. The impact of the inserted loops on the stability of the enzyme was analyzed using molecular dynamics (MD) and the effect on the active site was studied using molecular mechanics (MM) simulations. The best loop mutation predicted in silico (EGI_L5) was introduced to EGI via site directed mutagenesis. The loop mutant EGI_L5 and EGI were both expressed in Pichia pastoris. Enzymes were characterized and their activities against soluble substrates such as CMC and 4-MUC were determined. Both enzymes exhibited similar pH and temperature activity and thermal stability profiles. Moreover, specific activity of EGI_L5 against 4-MUC was found to be the same as the native enzyme. 相似文献
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Dahia PL Ross KN Wright ME Hayashida CY Santagata S Barontini M Kung AL Sanso G Powers JF Tischler AS Hodin R Heitritter S Moore F Dluhy R Sosa JA Ocal IT Benn DE Marsh DJ Robinson BG Schneider K Garber J Arum SM Korbonits M Grossman A Pigny P Toledo SP Nosé V Li C Stiles CD 《PLoS genetics》2005,1(1):72-80
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Patricia L. M Dahia Ken N Ross Matthew E Wright César Y Hayashida Sandro Santagata Marta Barontini Andrew L Kung Gabriela Sanso James F Powers Arthur S Tischler Richard Hodin Shannon Heitritter Francis Moore Jr. Robert Dluhy Julie Ann Sosa I. Tolgay Ocal Diana E Benn Deborah J Marsh Bruce G Robinson Katherine Schneider Judy Garber Seth M Arum Márta Korbonits Ashley Grossman Pascal Pigny Sérgio P. A Toledo Vania Nosé Cheng Li Charles D Stiles 《PLoS genetics》2005,1(1)
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Afshin Abrishamkar Markos Paradinas Elena Bailo Romen Rodriguez-Trujillo Raphael Pfattner René M. Rossi Carmen Ocal Andrew J. deMello David B. Amabilino Josep Puigmartí-Luis 《Journal of visualized experiments : JoVE》2016,(113)
The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. Herein, we introduce a microfluidic-based technology, employing a double-layer microfluidic device, which can trap and localize in situ and ex situ synthesized structures on microfluidic channel surfaces. Crucially, we show how such a device can be used to conduct controlled chemical reactions onto on-chip trapped structures and we demonstrate how the synthetic pathway of a crystalline molecular material and its positioning inside a microfluidic channel can be precisely modified with this technology. This approach provides new opportunities for the controlled assembly of structures on surface and for their subsequent treatment. 相似文献
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Aksoy HM Ozman-Sullivan SK Ocal H Celik N Sullivan GT 《Experimental & applied acarology》2008,46(1-4):223-230
This study investigated Pseudomonas putida biotype B as a potential biological control agent of Tetranychus urticae. The bacteria were isolated from greenhouse soil from Carsamba, Turkey. The experiment was carried out in a completely randomized plot design under laboratory conditions. For this purpose, spraying and dipping applications of a suspension of P. putida biotype B (10(8)-10(9) colony forming units/ml) were applied to newly emerged, copulated females. Dead mite and egg counts were started on the 3rd day after treatments, and observations were continued daily until all the mites had died and egg hatching had finished. Both types of bacterial application significantly reduced total egg numbers and egg hatching, compared to their respective controls. Bacterial spraying was significantly more effective than dipping-the spray application demonstrated 100% efficacy and resulted in the fewest viable eggs. The results of this study indicated that P. putida biotype B has a strong efficacy in causing mortality in T. urticae. 相似文献
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Berkan O Bagcivan I Kaya T Yildirim K Yildirim S Doğan K 《Canadian journal of physiology and pharmacology》2007,85(5):521-526
The radial artery (RA) is used as a spastic coronary bypass graft. This study was designed to investigate the mechanism of vasorelaxant effects of YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole), a nitric oxide (NO)-independent soluble guanylate cyclase (sGC) activator, and DEA/NO (diethylamine/nitric oxide), a NO-nucleophile adduct, on the human RA. RA segments (n = 25) were obtained from coronary artery bypass grafting patients and were divided into 3-4 mm vascular rings.Using the isolated tissue bath technique, the endothelium-independent vasodilatation function was tested in vitro by the addition of cumulative concentrations of YC-1 (10-10 to 3 x 10-7 mol/L) and DEA/NO (10-8 to 3 x 10-5 mol/L) following vasocontraction by phenylephrine in the presence or absence of 10-5 mol/L ODQ (1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one), the selective sGC inhibitor, 10-7 mol/L iberiotoxin, a blocker of Ca2+-activated K+ channels, or 10-5 mol/L ODQ plus 10-7 mol/L iberiotoxin. We also evaluated the effect of YC-1 and DEA/NO on the cGMP levels in vascular rings obtained from human radial artery (n = 6 for each drug). YC-1 (10-10 to 3 x 10-7 mol/L) and DEA/NO (10-8 to 3 x 10-5 mol/L) caused the concentration-dependent vasorelaxation in RA rings precontracted with phenylephrine (10-5 mol/L) (n = 20 for each drug). Pre-incubation of RA rings with ODQ, iberiotoxin, or ODQ plus iberiotoxin significantly inhibited the vasorelaxant effect of YC-1, but the inhibitor effect of ODQ plus iberiotoxin was significantly more than that of ODQ and iberiotoxin alone (p < 0.05). The vasorelaxant effect of DEA/NO almost completely abolished in the presence of ODQ and iberiotoxin plus ODQ, but did not significantly change in the presence of iberiotoxin alone (p > 0.05). The pEC50 value of DEA/NO was significantly lower than those for YC-1 (p < 0.01), with no change Emax values in RA rings. In addition, YC-1-stimulated RA rings showed more elevation in cGMP than that of DEA/NO (p < 0.05). These findings indicate that YC-1 is a more potent relaxant than DEA/NO in the human RA. The relaxant effects of YC-1 could be due to the stimulation of the sGC and Ca2+-sensitive K+channels, whereas the relaxant effects of DEA/NO could be completely due to the stimulation of the sGC. YC-1 and DEA/NO may be effective as vasodilator for the short-term treatment of perioperative spasm of coronary bypass grafts. 相似文献
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Trichoderma reesei cellulases are important biocatalysts for a wide range of industrial applications that include the paper, feed, and textile industries. T. reesei endoglucanase 1 (egl1) was successfully expressed as an active and stable catalyst in Pichia pastoris for the first time. Codon optimization was applied to egl1 of T. reesei to enhance its expression levels in P. pastoris. When compared with the originally cloned egl1 gene of T. reesei, the synthetic codon optimized egl1 gene (egl1s) was expressed at a higher level in P. pastoris. Batch fermentations of both clones with the same copy number under controlled conditions indicated that codon optimized EGI enzyme activity increased to 1.24 fold after 72 h of methanol induction. Our research indicated that P. pastoris is a suitable host for cellulase production. 相似文献
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Hematopoietic stem cell transplantation is the most powerful treatment modality for a large number of hematopoietic malignancies, including leukemia. Successful hematopoietic recovery after transplantation depends on homing of hematopoietic stem cells to the bone marrow and subsequent lodging of those cells in specific niches in the bone marrow. Migration of hematopoietic stem cells to the bone marrow is a highly regulated process that requires correct regulation of the expression and activity of various molecules including chemoattractants, selectins and integrins. This review will discuss recent studies that have extended our understanding of the molecular mechanisms underlying adhesion, migration and bone marrow homing of hematopoietic stem cells. 相似文献