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).     

Differentiation of mesenchymal stem cells to insulin-producing cells and their impact on type 1 diabetic rats

Cell therapy is thought to be a possible approach for treatment of diabetes. Cells with the ability to differentiate into insulin-producing cells (IPCs) would provide an unlimited source of islet cells for transplantation. In this study, the differentiation capacity of rat bone-marrow-derived mesenchymal stem cells (MSCs) to IPCs and the feasibility of using them for reversal of hyperglycemia were investigated. In vitro studies indicated that treatment of cells with high glucose concentration, nicotinamide and β-mercaptoethanol resulted to differentiated cells, which had characteristics of IPCs including spherical, grape-like morphology, secretion of insulin, and being positive for dithizone. To test the in vivo function of differentiated MSCs, they were injected into the spleen of diabetic rats. It was shown that diabetic rats who received IPCs, significantly reduced the glucose level, in response to intraperitoneal glucose tolerance (IPGT) test. These results indicate that MSCs are capable of in vitro differentiation into functional IPCs, which can reverse hyperglycemia in rat model of diabetes.     

A new on-line, in-tube pre-column derivatization technique for high performance liquid chromatographic determination of azithromycin in human serum

Pre-column derivatization methods for high performance liquid chromatographic assay of specific pharmaceutical agents using 9-fluorenylmethyl chloroformate (FMOC-Cl) have received special attention because highly fluorescent and stable adducts are provided by these methods. However, unlike the post-column on-line techniques, long derivatization time is needed and the reaction cannot be well controlled. A new, sensitive and fast pre-column on-line derivatization technique coupled with high-performance liquid chromatography using FMOC-Cl as labeling agent is described and validated for determination of azithromycin in human serum. After extraction of the drug from serum, the residue was reconstituted in mixture of acetonitrile-phosphate buffer (3:1, v/v; pH 8.5) and directly injected onto the chromatographic system. Continuous on-line derivatization and analysis of the compounds were successfully performed using in-tube elution of FMOC-Cl. The total time needed for derivatization and chromatographic analysis of the drug was 13 min. The assay was reliable and reproducible, with limit of quantification of 10 ng/ml. The described technique may offer significant advantages over existing off-line derivatization methods using FMOC-Cl.     

Over-expression of recombinant human interferon-gamma in high cell density fermentation of Escherichia coli

Human interferon-gamma (hIFN-gamma) was expressed in Escherichia coli BL21(DE3) under the control of the T7 promoter. Glucose was used as the sole source of carbon and energy with simple exponential feeding rate in fed-batch process. Cell density of recombinant E. coli was reached to 100 g dry wt l(-1) under both constant (0.12 h(-1)) and variable (0.12-0.52 h(-1)) specific growth rates. In the variable specific growth rate fed-batch process, plasmid stability and specific yield of rhIFN-gamma were greater than constant specific growth rate fed-batch process. The final specific yield and overall productivity of rhIFN-gamma were 0.35 +/- 0.02 g rhIFN-gamma g(-1) dry cell wt and 0.9 +/- 0.05 g rhIFN-gamma l(-1) h(-1) in the variable specific growth rate fed-batch process, respectively.     

Epr analysis reveals three tissues responding to endotoxin by increased formation of reactive oxygen and nitrogen species

The excessive formation of reactive oxygen and nitrogen species (RONS) in tissue has been implicated in the development of various diseases. In this study we adopted ex vivo low temperature EPR spectroscopy combined with spin trapping technique to measure local RONS levels in frozen tissue samples. CP-H (1-hydroxy-3-carboxy-pyrrolidine), a new nontoxic spin probe, was used to analyze RONS in vivo. In addition, nitrosyl complexes of hemoglobin were determined to trace nitric oxide released into blood. By this technique we found that RONS formation in tissue of control animals increased in the following order: liver < heart < brain < cerebellum < lung < muscle < blood < ileum < kidney < duodenum < jejunum. We also found that endotoxin challenge, which represents the most common model of septic shock, increased the formation of RONS in rat liver, heart, lung, and blood, but decreased RONS formation in jejunum. We did not find changes in RONS levels in other parts of gut, brain, skeletal muscles, and kidney. Scavenging of RONS by CP-H was accompanied by an increase in blood pressure, indicating that LPS-induced vasodilatation may be due to RONS, but not due to nitric oxide. Experiments with tissue homogenates incubated in vitro with CP-H showed that ONOO⁻ and O₂^•−, as well as other not identified RONS, are detectable by CP-H in tissue. In summary, low-temperature EPR combined with CP-H infusion allowed detection of local RONS formation in tissues. Increased formation of RONS in response to endotoxin challenge is organ specific.     

High performance liquid chromatographic determination of topiramate in human serum using UV detection

Topiramate has no ultraviolet, visible or fluorescence absorption. Analysis of the drug in human serum has been reported by high performance liquid chromatography (HPLC) with either mass detector or fluorescence detection after precolumn derivatization using 9-fluorenylmethyl chloroformate as fluorescent labeling agent. This study was aimed to validate derivatization and analysis of topiramate in human serum with HPLC using UV detection. The drug was extracted from human serum by liquid-liquid extraction and subjected to derivatization with 9-fluorenylmethyl chloroformate. Analysis was performed on a phenyl column using of spectrophotometer detection operated at wavelength of 264 nm. A mixture of phosphate buffer (0.05M) containing triethylamine (1 ml/l, v/v; pH 2.3) and methanol (28:72, v/v) at a flow rate of 2.5 ml/min was used as mobile phase. No interference was found with endogenous substances. Validity of the method was studied and the method was precise and accurate with a linearity range from 40 ng/ml to 40 microg/ml. The limit of quantification was 40 ng/ml of serum. The correlation coefficient between HPLC methods using fluorescence and UV detections was studied and found to be 0.992.     

Skeletal muscles, heart, and lung are the main sources of oxygen radicals in old rats

The aim of this study was to compare rat tissues with respect to their reactive oxygen and nitrogen species (RONS) generating activities as a function of age. We quantified the RONS generation in vivo in young (6 months) and in old (30 months) male Sprague-Dawley rats using the recently developed spin trap 1-hydroxy-3-carboxy-pyrrolidine, applied intravenously. This spin trap reacts with superoxide radical and peroxynitrite yielding a stable spin adduct which is detectable by means of electron paramagnetic resonance (EPR) spectroscopy in frozen tissues. In old rats RONS generation was significantly increased compared to their young counterparts in the following order: blood相似文献   

Probabilistic Identification of Spin Systems and their Assignments including Coil–Helix Inference as Output (PISTACHIO)

We present a novel automated strategy (PISTACHIO) for the probabilistic assignment of backbone and sidechain chemical shifts in proteins. The algorithm uses peak lists derived from various NMR experiments as input and provides as output ranked lists of assignments for all signals recognized in the input data as constituting spin systems. PISTACHIO was evaluate00000000d by comparing its performance with raw peak-picked data from 15 proteins ranging from 54 to 300 residues; the results were compared with those achieved by experts analyzing the same datasets by hand. As scored against the best available independent assignments for these proteins, the first-ranked PISTACHIO assignments were 80–100% correct for backbone signals and 75–95% correct for sidechain signals. The independent assignments benefited, in a number of cases, from structural data (e.g. from NOESY spectra) that were unavailable to PISTACHIO. Any number of datasets in any combination can serve as input. Thus PISTACHIO can be used as datasets are collected to ascertain the current extent of secure assignments, to identify residues with low assignment probability, and to suggest the types of additional data needed to remove ambiguities. The current implementation of PISTACHIO, which is available from a server on the Internet, supports input data from 15 standard double- and triple-resonance experiments. The software can readily accommodate additional types of experiments, including data from selectively labeled samples. The assignment probabilities can be carried forward and refined in subsequent steps leading to a structure. The performance of PISTACHIO showed no direct dependence on protein size, but correlated instead with data quality (completeness and signal-to-noise). PISTACHIO represents one component of a comprehensive probabilistic approach we are developing for the collection and analysis of protein NMR data.Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users.     

Anti-Inflammatory Activity of S. Marianum and N. Sativa Extracts on Macrophages

Background:Nigella sativa (N. sativa) and Silybum marianum (S. marianum) are used to regulate macrophage polarization in lipopolysaccharide-induced RAW 264.7 cells and thioglycollate-elicited peritoneal inflammation.Methods:Cytotoxicity assays and acute toxicity tests were performed to investigate the safe dose and toxicity of the prepared extracts. Also, nitric oxide production was determined by Griess assay on RAW264.7 and peritoneal macrophage supernatants. After RNA extraction from macrophages, real-time PCR was performed to measure the relative gene expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6, transforming growth factor (TGF)-β, and IL-10. Finally, regulatory T cells (Treg cells) were counted by flow cytometry.Results:S. marianum methanolic extract (SME), N. sativa ethanolic extract (NEE), and their mixture (SME+NEE) decreased NO levels significantly in RAW264.7 and peritoneal murine macrophages. N. sativa ethanolic extract significantly increased IL-10 gene expression and significantly decreased IL-6 and TNF-α expression in RAW264.7 cells. In mixture-treated peritoneal macrophages, IL-10 and TGF-β expression were significantly increased, while IL-6 and TNF-α were significantly decreased. Also, the percentage of Treg cells was significantly greater in the mixture-treated cells than in controls.Conclusion:These results suggest that an SME and NEE mixture has anti-inflammatory and immunomodulatory activities and may be useful in the treatment of diseases of immunopathologic origin characterized by macrophage hyperactivation.Key Words: Cytokine, Inflammation, Nigella sativa, Nitric oxide, Silybum marianum