Self-Organization, Layered Structure, and Aggregation Enhance Persistence of a Synthetic Biofilm Consortium

Microbial consortia constitute a majority of the earth’s biomass, but little is known about how these cooperating communities persist despite competition among community members. Theory suggests that non-random spatial structures contribute to the persistence of mixed communities; when particular structures form, they may provide associated community members with a growth advantage over unassociated members. If true, this has implications for the rise and persistence of multi-cellular organisms. However, this theory is difficult to study because we rarely observe initial instances of non-random physical structure in natural populations. Using two engineered strains of Escherichia coli that constitute a synthetic symbiotic microbial consortium, we fortuitously observed such spatial self-organization. This consortium forms a biofilm and, after several days, adopts a defined layered structure that is associated with two unexpected, measurable growth advantages. First, the consortium cannot successfully colonize a new, downstream environment until it selforganizes in the initial environment; in other words, the structure enhances the ability of the consortium to survive environmental disruptions. Second, when the layered structure forms in downstream environments the consortium accumulates significantly more biomass than it did in the initial environment; in other words, the structure enhances the global productivity of the consortium. We also observed that the layered structure only assembles in downstream environments that are colonized by aggregates from a previous, structured community. These results demonstrate roles for self-organization and aggregation in persistence of multi-cellular communities, and also illustrate a role for the techniques of synthetic biology in elucidating fundamental biological principles

Isolation and characterisation of human gingival margin-derived STRO-1/MACS+ and MACS− cell populations

Recently, gingival margin-derived stem/progenitor cells isolated via STRO-1/magnetic activated cell sorting (MACS) showed remarkable periodontal regenerative potential in vivo. As a second-stage investigation, the present study's aim was to perform in vitro characterisation and comparison of the stem/progenitor cell characteristics of sorted STRO-1-positive (MACS+) and STRO-1-negative (MACS−) cell populations from the human free gingival margin. Cells were isolated from the free gingiva using a minimally invasive technique and were magnetically sorted using anti-STRO-1 antibodies. Subsequently, the MACS+ and MACS− cell fractions were characterized by flow cytometry for expression of CD14, CD34, CD45, CD73, CD90, CD105, CD146/MUC18 and STRO-1. Colony-forming unit (CFU) and multilineage differentiation potential were assayed for both cell fractions. Mineralisation marker expression was examined using real-time polymerase chain reaction (PCR). MACS+ and MACS− cell fractions showed plastic adherence. MACS+ cells, in contrast to MACS− cells, showed all of the predefined mesenchymal stem/progenitor cell characteristics and a significantly higher number of CFUs (P<0.01). More than 95% of MACS+ cells expressed CD105, CD90 and CD73; lacked the haematopoietic markers CD45, CD34 and CD14, and expressed STRO-1 and CD146/MUC18. MACS− cells showed a different surface marker expression profile, with almost no expression of CD14 or STRO-1, and more than 95% of these cells expressed CD73, CD90 and CD146/MUC18, as well as the haematopoietic markers CD34 and CD45 and CD105. MACS+ cells could be differentiated along osteoblastic, adipocytic and chondroblastic lineages. In contrast, MACS− cells demonstrated slight osteogenic potential. Unstimulated MACS+ cells showed significantly higher expression of collagen I (P<0.05) and collagen III (P<0.01), whereas MACS− cells demonstrated higher expression of osteonectin (P<0.05; Mann–Whitney). The present study is the first to compare gingival MACS+ and MACS− cell populations demonstrating that MACS+ cells, in contrast to MACS− cells, harbour stem/progenitor cell characteristics. This study also validates the effectiveness of the STRO-1/MACS+ technique for the isolation of gingival stem/progenitor cells. Human free gingival margin-derived STRO-1/MACS+ cells are a unique renewable source of multipotent stem/progenitor cells

Derivation of an optimal boundary layer width for the smooth variable structure filter

In this paper, an augmented form of the smooth variable structure filter (SVSF) is proposed. The SVSF is a state estimation strategy based on variable structure and sliding mode concepts. It uses a smoothing boundary to remove chattering (excessive switching along an estimated state trajectory). In its current form, the SVSF defines the boundary layer by an upper-bound on the uncertainties present in the estimation process (i.e., modeling errors, magnitude of noise, etc.). This is a conservative approach as one would be limiting the gain by assuming a larger smoothing boundary subspace than what is necessary. A more well-defined boundary layer will yield more accurate estimates. This paper derives a solution for an optimal boundary layer width by minimizing the trace of the a posteriori covariance matrix. The results of the derivation are simulated on a linear mechanical system for the purposes of control, and compared with the Kalman filter. © 2011 AACC American Automatic Control Council

The use of medicinal plants in health care practices by Rohingya refugees in a degraded forest and conservation area of Bangladesh

People in developing countries traditionally rely on plants for their primary healthcare. This dependence is relatively higher in forests in remote areas due to the lack of access to modern health facilities and easy availability of the plant products.We carried out an ethno-medicinal survey in Teknaf Game Reserve (TGR), a heavily degraded forest and conservation area in southern Bangladesh, to explore the diversity of plants used by Rohingya refugees for treating various ailments. The study also documented the traditional utilization, collection and perceptions of medicinal plants by the Rohingyas residing on the edges of this conservation area. We collected primary information through direct observation and by interviewing older respondents using a semi-structured questionnaire. A total of 34 plant species in 28 families were frequently used by the Rohingyas to treat 45 ailments, ranging from simple headaches to highly complex eye and heart diseases. For medicinal preparations and treating various ailments, aboveground plant parts were used more than belowground parts. The collection of medicinal plants was mostly from the TGR. © 2009 Taylor & Francis

Molecular and biological characterization of Trichogramma turkestanica

Parasitoids of Trichogramma (Hymenoptera: Trichogrammatidae) parasitize the eggs of many species of Lepidoptera and have been used for the biological control of numerous pest species. We collected this parasitoid from Taif governorate, KSA in summer of 2009. It is difficult to differentiate between Trichogramma species because of their small size and lack of differences in morphological characters. Therefore, different molecular markers were employed to characterize this species, including direct amplification of the internal transcribed spacer 2 (ITS2) of ribosomal DNA and by restriction fragment length polymorphism followed by sequencing. The results show that ITS2 region is 491 bp and indicated that this is a new stain of Trichogramma. We named this strain TaifKSA. From the tested restriction enzymes, only EcoRI and PstI cut the PCR product of ITS2 region. We compared the biological characteristics of the strain under investigation with other commercial strain (SQG) of the same species and no significant differences between them have been shown.Key words: Trichogramma turkestanica, TaifKSA, molecular identification, internal transcribed spacer 2 (ITS2), restriction enzymes, biological characteristics

Fault Detection of an Engine Using a Neural Network Trained by the Smooth Variable Structure Filter

A multilayered neural network is a multi-input, multi-output (MIMO) nonlinear system in which training can be regarded as a nonlinear parameter estimation problem by estimating the network weights. In this paper, the relatively new smooth variable structure filter (SVSF) is used for the training of a nonlinear multilayered feed forward network. The SVSF is a recursive sliding mode parameter and state estimator that has a predictor-corrector form. Using a switching gain, a corrective term is calculated to force the network weights to converge to within a neighbourhood of the optimal weight values. SVSF-based trained neural networks are used to classify engine faults on the basis of vibration data. Two faults are induced in a four-stroke, eight-cylinder engine. Furthermore, a comparative study between the popular back propagation method, the extended Kalman filter (EKF), and the SVSF is presented. Experimental results indicate that the SVSF is comparable with the EKF, and both methods outperform back propagation. © 2011 IEEE

Molecular epidemiology of antibiotic-associated diarrhoea due to Clostridium difficile and clostridium perfringens in Ain Shams University Hospitals

Background: As we are living in the era of antibiotic overuse, antibiotic associated diarrhea (AAD) is considered now a distinct health problem with a need for more attention. Aim of the Study: was to perform a highly specific detection and definition of pathogenic Clostridium perfringens and Clostridium difficile related AAD in children compared to adults and geriatircs. Patients and Methods: One hundred and fifty patients diagnosed for AAD were included in this study (50 children, 50 adults and 50 geriatric patients). All of them were subjected to full medical history including complete therapeutic history of antibiotics and collection of stool sample during the attack for detection of Clostridium perfringenes enterotoxin (CPEnt) and Clostridium difficile cytotoxin by (EIA) kit. PCR detection of Clostridium perfringenes cpe gene (Coding gene for CPEnt) was performed as well. Results: Results showed that prevalence of Clostridium difficile cytotoxin was 24% while Clostridium perfringenes enterotoxin was 12% as detected by EIA in faecal specimens as a whole. Detection of cpe gene by PCR was positive in 16% of all cases. Children (OR: 4.2, 95% CI: 1.3-14.8, P_0.01) and geriatric patients (OR: 3.4, 95% CI: 1.2-13.5, P_0.02) were significantly more prone to Clostridium difficile AAD compared to adults. Also, childhood was a significant risk for Clostridium perfringens AAD (OR: 2.1, 95% CI: 0.54-7.4, P_0.04). In Conclusion: children and geriatric patients are more vulnerable to develop AAD with antibiotic abuse compared to adults. Abbreviations: AAD=Antibiotic associated diarrhea, CI=Confidence interval, ELISA=Enzyme-linked immunosorbent assay, OR=Odd ratio, PCR=Polymerase chain reaction. Keywords: Antibiotic-associated diarrhea, children, Clostridium perfringens, Clostridium difficile. Egypt. J. Hum. Genet Vol. 8 (2) 2007: pp. 121-13

Salivary PCR detection of Helicobacter pylori DNA in Egyptian patients with dyspepsia

Several methods are available for detecting Helicobacter pylori infection: (1) invasive methods based on gastric biopsies, (2) non invasive methods like Urea Breath Test (UBT), serology and stool antigen tests. Importance of salivary PCR in detection of H. pylori is still questionable. To evaluate the role of salivary PCR technique in detecting H. pylori gastric affection in Egyptian patients with dyspepsia and in differentiating between functional dyspepsia and acid-ulcer syndrome. This study included 60 patients with dyspepsia classified into three groups: (Group 1) patients with gastric H. pylori and ulcers or erosions (n= 20), (Group 2) patients with gastric H. pylori and no ulcers or erosions and had functional dyspepsia (n= 20), (Group 3) patients without H. pylori and had functional dyspepsia (n= 20). All underwent upper gastrointestinal endoscopy with biopsies, rapid urease test and salivary samples for H. pylori PCR. Significant difference between the three groups regarding salivary PCR values. No significant difference between Group 1 and Group 2 but both had significant difference with Group 3, significant difference between gastric H. pylori positive patients (n= 40) and negative ones (n= 20). Salivary PCR test had sensitivity of 85%, specificity of 70% in diagnosing H. pylori. PCR value of 534000 Iu/ml had best sensitivity (75%) and specificity (100%) for diagnosing H. pylori, highly significant positive correlation between H. pylori gastric affection and salivary PCR values. No significant difference between patients with acid ulcer syndrome (n=20) and those with functional dyspepsia (n= 40) as regard salivary PCR mean values. Salivary PCR test showed sensitivity of 100%, specificity of 50% in differentiating between patients with acid ulcer syndrome and those with functional dyspepsia. PCR value of 440000 Iu/ml had best sensitivity (100%) and specificity (55%) in differentiating acid ulcer syndrome from functional dyspepsia with non significant. H. pylori salivary PCR may be of value in diagnosing H. pylori gastric affection and is strongly correlated with it but it is of limited value in differentiating between acid ulcer syndrome and functional dyspepsia.Keywords: Salivary PCR; Helicobacter pylori; Functional dyspepsia; Acid ulcer syndrom

A Signal-Based Fault Detection and Classification Strategy with Application to an Internal Combustion Engine

Fault detection strategies are important for ensuring the safe and reliable operation of mechanical and electrical systems. Recently, a new signal-based fault detection and classification strategy has been proposed, which makes use of artificial neural networks (NNs) and the smooth variable structure filter (SVSF). The strategy, referred to as the NN-SVSF, has shown promising results with applications to benchmark classification problems. New developments of the SVSF have resulted in improved performance in terms of state and parameter estimation. These developments are used to enhance the NN-SVSF in an effort to further advance the signal-based strategy. This paper studies and compares the results of applying other popular strategies on an internal combustion engine (ICE), for the purposes of fault detection and classification. © 2012 IEEE

Automotive Internal-Combustion-Engine Fault Detection and Classification Using Artificial Neural Network Techniques

In this paper, an engine fault detection and classification technique using vibration data in the crank angle domain is presented. These data are used in conjunction with artificial neural networks (ANNs), which are applied to detect faults in a four-stroke gasoline engine built for experimentation. A comparative study is provided between the popular backpropagation (BP) method, the Levenberg-Marquardt (LM) method, the quasi-Newton (QN) method, the extended Kalman filter (EKF), and the smooth variable structure filter (SVSF). The SVSF is a relatively new estimation strategy, based on the sliding mode concept. It has been formulated to efficiently train ANNs and is consequently referred to as the SVSF-ANN. The accuracy of the proposed method is compared with the standard accuracy of the Kalman-based filters and the popular BP algorithms in an effort to validate the SVSF-ANN performance and application to engine fault detection and classification. The customizable fault diagnostic system is able to detect known engine faults with various degrees of severity, such as defective lash adjuster, piston chirp (PC), and chain tensioner (CT) problems. The technique can be used at any dealership or assembly plant to considerably reduce warranty costs for the company and manufacturer