All-Optical Tunable Plasmonic Biosensor Made of Graphene and Metamaterial

Plasmonics - We demonstrate a novel, label-free and real-time tunable infrared biosensor by employing surface-plasmon polaritons in asymmetric Mach–Zehnder interferometer. The waveguides...     

Comparative Evaluation of α-Amylase Refolding Through Two Different Artificial Chaperone Systems

Two different artificial chaperone systems were evaluated in this work using either detergents or CDs as the stripping agents. Upon dilution of urea-denatured α-amylase to a non-denaturing urea concentration in the presence of the capturing agent, complexes of the detergent and non-native protein molecules are formed and thereby the formation of protein aggregates is prevented. The so-called captured protein is unable to refold from the detergent-protein complex states unless a stripping agent is used to remove the detergent molecules. Our results by fluorescence, UV, turbidity measurement, circular dichroism, surface tension and activity assay indicated that the extent of refolding assistance was different due to different inter- and intra- molecular interactions in the two different systems. However, the high activity recovery in the presence of detergents, as the stripping agent, suggests that they can constitute suitable replacement for the more expensive and common stripping agent of cyclodextrins.     

A faunistic study on the leafhoppers of northwestern Iran (Hemiptera,Cicadellidae)

The leafhopper fauna of northwestern Iran: Azarbaijan-e-Sharghi, Azarbaijan-e-Gharbi and Ardabil provinces is listed from previously published records and from our current work. Sixty-nine species are included with four species (Mogangella straminea Dlabola, 1957, Doratura stylata (Boheman, 1847), Macrosteles sordidipennis (Stål, 1858) and Psammotettix seriphidii Emeljanov, 1962) listed as new for Iran and Balclutha punctata (Fabricius, 1775), as a new record for the region. A distribution map of the species in northwestern Iran is given.     

Modified thalamocortical model: A step towards more understanding of the functional contribution of astrocytes to epilepsy

It is evident that the cortex plays a primary role in seizure generation. At the same time, various experimental results clearly confirm that thalamic neurons are also actively involved in seizure generation and spreading. On the other hand, recent neurophysiologic findings suggest that astrocytes regulate dynamically the synaptic activity in neuronal networks. Therefore, in the present study, the thalamocortical neural population model (TCPM) is modified by embedding into the model the functional role of astrocytes in the regulation of synaptic transmission. Using the modified TCPM (MTCPM) we examined the hypothesis that one of the possible causes of neural hypersynchronization is the dysfunction of astrocytes in the regulatory feedback loop. Then, two MTCPMs are coupled via excitatory synapses and the astrocytes are also coupled together through gap junctions. Utilizing the MTCPM and CMTCPM, the transition from normal to malfunctioned states is analyzed using a dynamical system approach. In this way, the hypothesis is investigated and it is demonstrated that the healthy astrocytes provide feedback control to regulate neural activity. That is, the astrocytes compensate to a large extent variations in the coupling between neural populations and maintain the balance between the excitation and inhibition levels. However, the malfunctioned astrocytes are no longer able to regulate and/or compensate the excessive increase of the inter-population coupling strength. As a consequence, disruption of the signaling function of astrocytes could contribute to the neuronal hyperexcitability and generating epileptiform activity. These results suggest that astrocytes might be one of the potential targets for the treatment of epilepsy.     

Analyses of Arabidopsis trr14 T-DNA Insertion Mutants Reveal an Essential Role in Seed Germination

TRR14 is an unknown protein that was first identified as a component of Arabidopsis responses to trehalose treatment. Phylogenic analysis showed that TRR14 belongs to a seven-gene family in Arabidopsis. Close homologues of TRR14 were found in plants and many cyanobacteria. GFP expression analysis showed that TRR14 is located in the chloroplast. GUS::TRR14 expression was found in leaves, flowers, stems and siliques. We investigated the functional roles of TRR14 in Arabidopsis thaliana under salt and drought stress. By a reverse genetic approach, two trr14 T-DNA insertion mutants were isolated from the SALK collection. Functional analysis of the trr14 mutants revealed enhanced sensitivity of the mutants to salt and drought stress, compared with the wild type plants. Further experiments indicated that the trr14 mutants have reduced seed germination, root length, survival rate and chlorophyll content under stress conditions. In addition activity of oxidative enzymes like peroxidase, catalase and polyphenol oxidase was reduced under salt and drought treatments. Thus, the present data indicate that a novel protein, TRR14, is involved in plant salt and drought tolerance.     

Phototaxis and impaired motility in adenylyl cyclase and cyclase receptor protein mutants of Synechocystis sp. strain PCC 6803

We have carefully characterized and reexamined the motility and phototactic responses of Synechocystis sp. adenylyl cyclase (Cya1) and catabolite activator protein (SYCRP1) mutants to different light regimens, glucose, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, and cyclic AMP. We find that contrary to earlier reports, cya1 and sycrp1 mutants are motile and phototactic but are impaired in one particular phase of phototaxis in comparison with wild-type Synechocystis sp.     

Vascular wall resident progenitor cells: a source for postnatal vasculogenesis

Here, we report the existence of endothelial precursor (EPC) and stem cells in a distinct zone of the vascular wall that are capable to differentiate into mature endothelial cells, hematopoietic and local immune cells, such as macrophages. This zone has been identified to be localized between smooth muscle and adventitial layer of human adult vascular wall. It predominantly contains CD34-positive (+) but CD31-negative (-) cells, which also express VEGFR2 and TIE2. Only few cells in this zone of the vascular wall are positive for CD45. In a ring assay using the fragments of human internal thoracic artery (HITA), we show here that the CD34+ cells of the HITA-wall form capillary sprouts ex vivo and are apparently recruited for capillary formation by tumor cells. New vessels formed by these vascular wall resident EPCs express markers for angiogenically activated endothelial cells, such as CEACAM1, and also for mature endothelial cells, such as VE-cadherin or occludin. Vascular wall areas containing EPCs are found in large and middle sized arteries and veins of all organs studied here. These data suggest the existence of a ;vasculogenic zone' in the wall of adult human blood vessels, which may serve as a source for progenitor cells for postnatal vasculogenesis, contributing to tumor vascularization and local immune response.     

MODEM: a multi-agent hierarchical structure to model the human motor control system

In this study, based on behavioral and neurophysiological facts, a new hierarchical multi-agent architecture is proposed to model the human motor control system. Performance of the proposed structure is investigated by simulating the control of sit to stand movement. To develop the model, concepts of mixture of experts, modular structure, and some aspects of equilibrium point hypothesis were brought together. We have called this architecture MODularized Experts Model (MODEM). Human motor system is modeled at the joint torque level and the role of the muscles has been embedded in the function of the joint compliance characteristics. The input to the motor system, i.e., the central command, is the reciprocal command. At the lower level, there are several experts to generate the central command to control the task according to the details of the movement. The number of experts depends on the task to be performed. At the higher level, a “gate selector” block selects the suitable subordinate expert considering the context of the task. Each expert consists of a main controller and a predictor as well as several auxiliary modules. The main controller of an expert learns to control the performance of a given task by generating appropriate central commands under given conditions and/or constraints. The auxiliary modules of this expert learn to scrutinize the generated central command by the main controller. Auxiliary modules increase their intervention to correct the central command if the movement error is increased due to an external disturbance. Each auxiliary module acts autonomously and can be interpreted as an agent. Each agent is responsible for one joint and, therefore, the number of the agents of each expert is equal to the number of joints. Our results indicate that this architecture is robust against external disturbances, signal-dependent noise in sensory information, and changes in the environment. We also discuss the neurophysiological and behavioral basis of the proposed model (MODEM).     

Discovery of potent inhibitors of interleukin-2 inducible T-cell kinase (ITK) through structure-based drug design

Interleukin-2 inducible T-cell kinase (ITK) is a member of the Tec kinase family and is involved with T-cell activation and proliferation. Due to its critical role in acting as a modulator of T-cells, ITK inhibitors could provide a novel route to anti-inflammatory therapy. This work describes the discovery of ITK inhibitors through structure-based design where high-resolution crystal structural information was used to optimize interactions within the kinase specificity pocket of the enzyme to improve both potency and selectivity.