309 research outputs found
On the total mass of asymptotically hyperbolic manifolds
Generalising a proof by Bartnik in the asymptotically Euclidean case, we give
an elementary proof of positivity of the hyperbolic mass near the hyperbolic
space.
It is a pleasure to dedicate this work to Robert Bartnik on the occasion of
his 60th birthday
PI3K/Akt inhibition and down-regulation of BCRP re-sensitize MCF7 breast cancer cell line to mitoxantrone chemotherapy
Objective(s): Multidrug resistance (MDR) of cancer cells is a major obstacle to successful chemotherapy. Overexpression of breast cancer resistance protein (BCRP) is one of the major causes of MDR. In addition, it has been shown that PI3K/Akt signaling pathway involves in drug resistance. Therefore, we evaluated the effects of novel approaches including siRNA directed against BCRP and targeted therapy against PI3K/Akt signaling pathway using LY294002 (LY) to re-sensitize breast cancer MCF7 cell line to mitoxantrone (MTX) chemotherapy. Materials and Methods: Anticancer effects of MTX, siRNA, and LY alone and in combination were evaluated in MCF7 cells using MTT cytotoxicity assay and flow cytometry analysis of cell cycle distribution and apoptosis induction. Results: MTT and apoptosis assays showed that both MTX and LY inhibited cell proliferation and induced apoptosis in MCF7 cells. Results indicated that inhibition of BCRP by siRNA or PI3K/Akt signaling pathway by LY significantly increased sensitivity of MCF7 cells to antiproliferation and apoptosis induction of MTX. Furthermore, MTX showed G2/M arrest, whereas LY induced G0/G1 arrest in cell cycle distribution of MCF7 cells. Combination of siRNA or LY with MTX chemotherapy significantly increased accumulation of MCF7 cells in the G2/M phase of cell cycle. Conclusion: Combination of MTX chemotherapy with BCRP siRNA and PI3K/Akt inhibition can overcome MDR in breast cancer cells. This study furthermore suggests that novel therapeutic approaches are needed to enhance anticancer effects of available drugs in breast cancer. ĂŠ 2015, Iranian Journal of Basic Medical Sciences. All rights reserved
The Evaluation of Growth, Yield and Physiological Responses of African Horned Cucumber (Cucumis metuliferus L.) to Deficit Irrigation
Introduction
Water stress is the most prominent abiotic stress limiting agricultural crop growth and productivity. Deficit irrigation stress as a consequence of the progressive decrease in water availability has been a hot topic regarding food security during the last two decades. Growth and development of plants is influenced by reduction in turgor that results in decreased nutrient acquisition from dry soil. When water supply is limited, plant growth and yield is reduced and plant structure is modified by decreasing in leaf size. The effect of deficit irrigation on fruit yield and quality has been reported by numerous researchers with different results. In melon, deficit irrigation reduced marketable fruit number and yield, average fruit weight, fruit diameter and did not affect rind thickness and seed cavity, but increased total soluble solids content. Although the effects of water stress have been studied on growth and yield of different crops during the last years, recent information on the response of African horned cucumber yield and quality to deficit irrigation remains limited, particularly about the results of restricted water distributions in arid and sub-arid environments. The main goal of this study was to evaluate the effect of controlled deficit irrigation on growth, physiological parameters and yield and fruit quality of African horned cucumber.
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Material and Methods
Field experiment was performed based on a completely randomized block design with three irrigation regimes (60, 80 and 100 %ETc), whit three replications at Research Farm of University of Zanjan during the 2019. The African horned cucumber seeds were sown on 1th July 2020 at recommended spacing of 50 cm in row with 120 cm between rows. The irrigation system consisted of one drip line every crop row. The three irrigation levels were calculated based on actual evapotranspiration (ETc): (1) control, irrigated 100% crop water requirement, (2) deficit irrigation 80% ETc and (3) deficit irrigation 60% ETc. The Water requirement of the plant for control treatment was estimated using long-term average daily data of meteorological parameters recorded at Zanjan Meteorological Station and following relation. Before starting the differential irrigation at five-leaf stage, all treatments were supplied with similar amount of water to maximize stands and uniform crop establishment. During plant growth, the relative water content, proline content, electrolyte leakage, chlorophyll and carotenoids, P and K contents were measured. After fruit harvest, vine length of each plant, leaf dry weight and stem diameter were measured. The fruits were harvested when color changed from green to yellow. Fruit weight, fruit number per plant and fruit yield per plant was measured. Immediately after harvest, fruit firmness, total soluble solid, total phenols content, antioxidant capacity and vitamin C were determined.
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Results and Discussion
As the results showed water deficit stress significantly reduced plant length, chlorophyll content, and increased carotenoids content. Based on the findings, deficit irrigation caused a significant reduction in leaf relative water content. According to the results, phosphorus and potassium contents in African horned cucumber leaves decreased with deficit irrigation treatments. The highest P and K contents were found under irrigation 100 %ETc treatment. Drought stress and associated reduction in soil moisture can decrease plant nutrient uptake by reducing nutrient supply through mineralization. The proline content increased with the deficit irrigation treatments; in particular with sever deficit irrigation (60 %ETc). Mean comparisons of data showed that deficit irrigation led to a significant increase in electrolyte leakage compared to control.
Water deficit stress caused significant reductions in yield. The highest fruit number per plant and yield were obtained under irrigation 100% ETc. The average fruit weigh significantly increased in response to increase water deficit stress. Deficit irrigation treatments significantly decreased vitamin C and fruit firmness. Significant differences among irrigation treatments were observed for total phenols and total soluble solid contents. The phenols and total soluble solid contents increased with the decrease of irrigation water applied. Antioxidant capacity was affected significantly by the irrigation treatments, and water deficit stress increased antioxidant capacity, which no significant difference was observed between irrigation 100 and 80 %ETc.
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Conclusion
Water deficit has been shown to adversely affect plant growth, fruit yield, and leaf water status of African horned cucumber, but led to increase the TSS and antioxidant capacity. According to the results, fruit yield reduced 13.9 % under irrigation 80% ETc compared to irrigation 100% ETc, However, water consumption was saved by 20% and improved fruit weight and fruit quality with increasing soluble solids and antioxidant capacity
Proton-Coupled Electron-Transfer Mechanism for the Radical Scavenging Activity of Cardiovascular Drug Dipyridamole
Dipyridamole (DIP) is a well-known pharmaceutical drug used as a coronary vasodilator and anti-platelet agent in clinics for treating several cardiovascular diseases. Primarily, the therapeutic effects of the drug are attributed to its antioxidant potency. In this research, we aim to declare the unknown antioxidant mechanism of DIP as well as its potent chain-breaking antioxidant activity in polar aqueous medium inside the cells, using different experimental methods and theoretical quantum calculations. Data demonstrated the higher antioxidant capacity of DIP against ROS and free radicals in polar cell's interior. DIP is capable of generating long living and noninvasive DIP⢠radicals in oxidant condition that leads to an effective âchain-breaking antioxidantâ activity. Quantum computational data indicated that DIP antioxidant has more favorable ionization potential than trolox which means DIP has higher antioxidant activity. Also, data showed that the direct hydrogen-transfer is not a favorable process to construct DIP⢠because of high barrier energy, though electron-transfer process can more easily to produce DIPâ˘+ with the lowest barrier energy. Altogether, the electron donating potency of DIP to reduce ferric ion, having the low anodic oxidation peak potential, producing long lived stable DIP⢠radicals and protecting myoblast cells from oxidation, proposed the excellent âchain-breaking antioxidantâ potency via electron-transfer mechanism of this vasodilator DIP drug in polar aqueous medium
Method for in-solution, high-throughput T1 relaxometry using fluorescent nanodiamonds
Fluorescent nanodiamonds (FNDs) have been exploited as sensitive quantum
probes for nanoscale chemical and biological sensing applications, with the
majority of demonstrations to date relying on the detection of single FNDs.
This places significant limits on the measurement time, throughput and
statistical significance of a measured result as there is usually marked
inhomogeneity within FND samples. Here we have developed a measurement platform
that can report the T1 spin relaxation time from a large ensemble of FNDs in
solution. We first describe a refined sensing protocol for this modality and
then use it to identify the optimal FND size for the detection of paramagnetic
targets. Our approach is simple to set up, robust and can be used for rapid
material characterisation or a variety of in-situ quantum sensing applications.Comment: 8 pages, 3 figure
Small palladium islands embedded in palladium-tungsten bimetallic nanoparticles form catalytic hotspots for oxygen reduction
The sluggish kinetics of the oxygen reduction reaction at the cathode side of proton exchange membrane fuel cells is one major technical challenge for realizing sustainable solutions for the transportation sector. Finding efficient yet cheap electrocatalysts to speed up this reaction therefore motivates researchers all over the world. Here we demonstrate an efficient synthesis of palladium-tungsten bimetallic nanoparticles supported on ordered mesoporous carbon. Despite a very low percentage of noble metal (palladium: tungsten = 1:8), the hybrid catalyst material exhibits a performance equal to commercial 60% platinum/Vulcan for the oxygen reduction process. The high catalytic efficiency is explained by the formation of small palladium islands embedded at the surface of the palladium-tungsten bimetallic nanoparticles, generating catalytic hotspots. The palladium islands are similar to 1 nm in diameter, and contain 10-20 palladium atoms that are segregated at the surface. Our results may provide insight into the formation, stabilization and performance of bimetallic nanoparticles for catalytic reactions
Solvothermal synthesis of NiAl double hydroxide microspheres on a nickel foam-graphene as an electrode material for pseudo-capacitors
In this paper, we demonstrate excellent pseudo-capacitance behavior of nickelaluminum
double hydroxide microspheres (NiAl DHM) synthesized by a facile
solvothermal technique using tertbutanol as a structure-directing agent on nickel
foam-graphene (NF-G) current collector as compared to use of nickel foam current
collector alone. The structure and surface morphology were studied by X-ray
diffraction analysis, Raman spectroscopy and scanning and transmission electron
microscopies respectively. NF-G current collector was fabricated by chemical vapor
deposition followed by an ex situ coatingmethod of NiAlDHMactivematerial which
forms a composite electrode. The pseudocapacitive performance of the composite
electrode was investigated by cyclic voltammetry, constant chargeâdischarge and
electrochemical impedance spectroscopy measurements. The composite electrode
with the NF-G current collector exhibits an enhanced electrochemical performance
due to the presence of the conductive graphene layer on the nickel foam and gives a
specific capacitance of 1252 F gâ1 at a current density of 1 A gâ1 and a capacitive
retention of about 97% after 1000 chargeâdischarge cycles. This shows that these
composites are promising electrode materials for energy storage devices.A.T.C.J acknowledges support from the LRSM, through the U.S. National Science
Foundation MRSEC, Grant No. DMR-1120901. D M acknowledges the financial support from the
University of Pretoria and the NRF Doctorate Innovation Fund for his study.http://scitation.aip.org/content/aip/journal/advaam201
Protocol of a prospective multicenter study on comorbidity impact on multiple sclerosis and antibody-mediated diseases of the central nervous system (COMMIT)
Comorbidities in patients with multiple sclerosis (MS) and antibody-mediated diseases of the central nervous system (CNS) including neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG)-antibody-associated disease (MOGAD) are common and may influence the course of their neurological disease. Comorbidity may contribute to neuronal injury and therefore limit recovery from attacks, accelerate disease progression, and increase disability. This study aims to explore the impact of comorbidity, particularly vascular comorbidity, and related risk factors on clinical and paraclinical parameters of MS, NMOSD and MOGAD. We propose COMMIT, a prospective multicenter study with longitudinal follow-up of patients with MS, NMOSD, and MOGAD, with or without comorbidities, as well as healthy subjects as controls. Subjects will be stratified by age, sex and ethnicity. In consecutive samples we will analyze levels of inflammation and neurodegeneration markers in both fluid and cellular compartments of the peripheral blood and cerebrospinal fluid (CSF) using multiple state-of-the-art technologies, including untargeted proteomics and targeted ultrasensitive ELISA assays and quantitative reverse transcription polymerase chain reaction (RT-qPCR) as well as high-dimensional single-cell technologies i.e., mass cytometry and single-cell RNA sequencing. Algorithm-based data analyses will be used to unravel the relationship between these markers, optical coherence tomography (OCT) and magnetic resonance imaging (MRI), and clinical outcomes including frequency and severity of relapses, long-term disability, and quality of life. The goal is to evaluate the impact of comorbidities on MS, NMOSD, and MOGAD which may lead to development of treatment approaches to improve outcomes of inflammatory demyelinating diseases of the CNS
Whole genome sequencing reveals a 7 base-pair deletion in DMD exon 42 in a dog with muscular dystrophy
Dystrophin is a key cytoskeletal protein coded by the Duchenne muscular dystrophy (DMD) gene located on the X-chromosome. Truncating mutations in the DMD gene cause loss of dystrophin and the classical DMD clinical syndrome. Spontaneous DMD gene mutations and associated phenotypes occur in several other species. The mdx mouse model and the golden retriever muscular dystrophy (GRMD) canine model have been used extensively to study DMD disease pathogenesis and show efficacy and side effects of putative treatments. Certain DMD gene mutations in high-risk, the so-called hot spot areas can be particularly helpful in modeling molecular therapies. Identification of specific mutations has been greatly enhanced by new genomic methods. Whole genome, next generation sequencing (WGS) has been recently used to define DMD patient mutations, but has not been used in dystrophic dogs. A dystrophin-deficient Cavalier King Charles Spaniel (CKCS) dog was evaluated at the functional, histopathological, biochemical, and molecular level. The affected dogâs phenotype was compared to the previously reported canine dystrophinopathies. WGS was then used to detect a 7 base pair deletion in DMD exon 42 (c.6051-6057delTCTCAAT mRNA), predicting a frameshift in gene transcription and truncation of dystrophin protein translation. The deletion was confirmed with conventional PCR and Sanger sequencing. This mutation is in a secondary DMD gene hotspot area distinct from the one identified earlier at the 5Ⲡdonor splice site of intron 50 in the CKCS breed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00335-016-9675-2) contains supplementary material, which is available to authorized users
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