280 research outputs found

    Cloning of taxadiene synthase gene into Arabidopsis thaliana (ecotype Columbia-0)

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    Paclitaxel (Taxol), a complex diterpenoid, produced by yew tree (Taxus sp.) is the most important chemotherapeutic agent that is widely used against a variety of malignancies such as ovarian and breast cancers. However, destructive methods for its production from natural resources together with currently used low-yielding industrial production systems via total synthesis or semi-synthesis have led researchers to invent a robust alternative biological production system using biotechnological approaches. The first committed step in taxol biosynthesis pathway is the  production of taxadiene from geranylgeranyl diphosphate (GGPP) catalyzed by the plastid-localized enzyme taxadiene synthase (TXS). In this research, an attempt was made to evaluate the effects of the first critical enzyme in thetaxol biosynthesis pathway on Arabidopsis plant through the expression of taxadiene synthase gene under the control of a dexamethasone-inducible promoter. To achieve this goal, Arabidopsis plants (ecotype Columbia-0) were transformed with the construct pTA-TXS-His via floral dip method using Agrobacterium tumefaciens AGL1. The transformed plants were confirmed using the PCR reaction amplifying an 800 bp fragment of the cloned gene. Upon these findings, a proposal was made that biotechnological strategies could be utilized for the production of taxol components

    Accuracy of doppler-derived indices in predicting pulmonary vascular resistance in children with pulmonary hypertension secondary to congenital heart disease with left-to-right shunting

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    This study aimed to evaluate the accuracy of Doppler echocardiography- derived indices in children with pulmonary hypertension secondary to congenital heart disease with left-to-right shunting. Doppler-derived indices including the acceleration time corrected (AcTc), deceleration time corrected, deceleration index, peak velocity, heart-rate-corrected inflection time (InTc), and a new index (the acceleration slope Acc = peak flow velocity/AcTc) were measured from the pulmonary artery (PA) systolic flow curve before and after 100 % oxygen administration in the main, left, and right PAs of 33 children. The acquired data were compared between low and high pulmonary vascular resistance (PVR) groups and between responders and nonresponders to the vasoreactivity test. The AcTc values differed significantly between the low and high PVR groups before and after oxygen administration in the main (P = 0.032 and <0.001, respectively), right (P = 0.011 and <0.001, respectively), and left (P < 0.001 and <0.001, respectively) PAs. The AcTc cutoff point in the main PA was 3.44 before oxygen administration (81 % sensitivity and 91 % specificity). The InTc in the main PA and its changes differed significantly between the low and high PVR groups before and after oxygen administration and between the responders and nonresponders (P = 0.016, 0.046, and 0.021, respectively). The velocity changes of the PA in the main PA differed significantly between the responders and nonresponders to oxygen administration (P < 0.001). The Acc and its changes differed significantly between the low and high PVR groups after oxygen administration and between the responders and nonresponders to oxygen administration (P = 0.044 and 0.006, respectively). Doppler echocardiographic examination using PA systolic flow indices in addition to PA reactivity testing is a promising technique for assessing PVR in children with congenital heart disease. © 2013 Springer Science+Business Media New York

    Full particle simulation of a perpendicular collisionless shock: A shock-rest-frame model

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    The full kinetic dynamics of a perpendicular collisionless shock is studied by means of a one-dimensional electromagnetic full particle simulation. The present simulation domain is taken in the shock rest frame in contrast to the previous full particle simulations of shocks. Preliminary results show that the downstream state falls into a unique cyclic reformation state for a given set of upstream parameters through the self-consistent kinetic processes.Comment: 4 pages, 2 figures, published in "Earth, Planets and Space" (EPS), the paper with full resolution images is http://theo.phys.sci.hiroshima-u.ac.jp/~ryo/papers/shock_rest.pd

    Percutaneous balloon pulmonary valvuloplasty of critical pulmonary stenosis and severe pulmonary stenosis in neonates and early infancy: A challenge in the cyanotic

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    Introduction: Pulmonary stenosis with an intact ventricular septum (PS-IVS) is one of the common causes of cyanotic heart disease in neonates with diverse morphologies as well as management and treatment protocols. The aim of this study was to evaluate short and midterm results of balloon pulmonary valvuloplasty (BPV) for this disorder. Methods: Between 2012 and 2016, Totally 45 neonates and infants under 6 months old were evaluated. The patients had a minimum right-to-left ventricular pressure ratio of 1, right-to-left shunting at the patent foramen ovale or atrial septal defect level, and tricuspid valve Z-scores higher than -4. Results: Immediately after the procedure, the right ventricular pressure dropped to the normal values in 8 (20) patients. The immediate procedural success rate was seen in 42 (93.3) cases: the right-to-left ventricular pressure ratio dropped to below 50 or the level of O2 saturation rose above 75. Of three cases unresponsive to BPV, two of them underwent patent ductus arteriosus (PDA) stenting and one procedural death occurred. At 6 months' follow-up, of 42 patients, this pressure was still within the normal range in 36 (80) infants, while it had returned to high values in 9 (20) patients and necessitated repeat valvuloplasty. After BPV, severe pulmonary valve regurgitation was observed in 14.2 patients; the condition was more common when high-profile noncompliant balloons were used. Conclusion: Balloon pulmonary valvuloplasty in infants with PS-IVS confers acceptable results insofar as it improves echocardiographic parameters and hemodynamic changes at short- and midterm follow-ups. Balloon selection with sizes more than 1.2 of the diameter of the pulmonary valve annulus and the use of noncompliant high-pressure balloons results in higher degrees of pulmonary regurgitation. © 2021 The Author(s)

    Ion Acceleration by Flux Transfer Events in the Terrestrial Magnetosheath

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    We report ion acceleration by flux transfer events in the terrestrial magnetosheath in a global two-dimensional hybrid-Vlasov polar plane simulation of Earth's solar wind interaction. In the model we find that propagating flux transfer events created in magnetic reconnection at the dayside magnetopause drive fast-mode bow waves in the magnetosheath, which accelerate ions in the shocked solar wind flow. The acceleration at the bow waves is caused by a shock drift-like acceleration process under stationary solar wind and interplanetary magnetic field upstream conditions. Thus, the energization is not externally driven but results from plasma dynamics within the magnetosheath. Energetic proton populations reach the energy of 30 keV, and their velocity distributions resemble time-energy dispersive ion injections observed by the Cluster spacecraft in the magnetosheath.Peer reviewe

    Environmental risk assessment of the activity of specific pathogen free shrimp production centers

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    This study is a part of the national and technology master plan entitled "Attain to technical knowledge of specific pathogen free shrimp production and cut off to dependence on foreign products". The goals of this work were to assess and analysis the risk factors of production of specific pathogen free Litopenaeus vannamei shrimp in its all stages (broodstocking, laravl production, shrimp farming, feeding and water quality), determining the pattern of outcomes monitoring, management and control of outcomes from April 2012 to September 2015 in Bandargah research station and Persian Gulf SPF Shrimp research station and their environment, belonging to Shrimp Research Center, located in Bushehr. Identification and screening of risk factors have been done based on Environment Aspect and Effect Analysis method, (EA)2, using a fine statement questionnaire and quantification of risks. The number of identified risk factors in Bandargah research station was 15 while it was 13 in Persian Gulf SPF Shrimp research station. The more number of risk factors in Bandargah station in respect to its number in Persian Gulf station is might due to lower level of biosecurity, physical structure and aging of Bandargah station and existence of two possible source of contamination, the Bushehr nuclear power plant pollutants and Bandargah fishing harbor, near to the station. On the basis of results, the maximum values of APN in Bandargah station was 42 while it was 30 in Persian Gulf station. These results revealed that the level of risk in Bandargah station is lower than that in Persian Gulf station. The most probable risks in both studied research stations are related to transmission of pathogens in shrimp feeding and water intake pollution

    New Clathrin-Based Nanoplatforms for Magnetic Resonance Imaging

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    Background: Magnetic Resonance Imaging (MRI) has high spatial resolution, but low sensitivity for visualization of molecular targets in the central nervous system (CNS). Our goal was to develop a new MRI method with the potential for non-invasive molecular brain imaging. We herein introduce new bio-nanotechnology approaches for designing CNS contrast media based on the ubiquitous clathrin cell protein. Methodology/Principal Findings: The first approach utilizes three-legged clathrin triskelia modified to carry 81 gadolinium chelates. The second approach uses clathrin cages self-assembled from triskelia and designed to carry 432 gadolinium chelates. Clathrin triskelia and cages were characterized by size, structure, protein concentration, and chelate and gadolinium contents. Relaxivity was evaluated at 0.47 T. A series of studies were conducted to ascertain whether fluorescent-tagged clathrin nanoplatforms could cross the blood brain barriers (BBB) unaided following intranasal, intravenous, and intraperitoneal routes of administration. Clathrin nanoparticles can be constituted as triskelia (18.5 nm in size), and as cages assembled from them (55 nm). The mean chelate: clathrin heavy chain molar ratio was 27.0464.8: 1 fo
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