Biocapteurs et bioélectronique

Image-guided near infrared spectroscopy has been implemented to deduce the map of oxygen consumption rate and blood flow rate of biological tissues using a model-based method combined the noninvasive diffuse light measurement techniques. The developed method relies on optical imaging to recover the concentrations of oxygen and de-oxygen hemoglobin concentration of tissues, and the ordinary differential equations to recover the vascular parameters including oxygen consumption rate and blood flow rate. In particular, the mathematical model has been validated by both simulation and experimental tests.

The advent of multi-sensor microelectrodes for extracellular action potential recordings has significantly improved the quality of recorded signals, allowing more reliable detection and classification of action potentials recorded in vivo. These microelectrodes can also be used to localize neuronal signal sources, which may allow experimentalists to estimate other parameters including the neurons’ migration trends, intensities and sizes. This information can also be used to resolve neurons based on their location and type. However, as the exact characteristics of neurons are unknown during in vivo experiments, current attempts to localize neuronal signal sources have not been validated. This article presents experimental validation of a method capable of estimating both the location and intensity of an electrical source. To this end, a stimulating electrode was immersed in a saline solution and its stimulus patterns were recorded by a commercially available four-sensor microelectrode (tetrode). The location of the tetrode was varied with respect to the stimulator, and for each tetrode position, the stimulus was generated at multiple intensity levels. The location and intensity of the source were estimated using the Multiple Signal Classification (MUSIC) algorithm, and the results were quantified by comparison to the parameters’ true values. Localization results, with an accuracy
and precision of ~10 μm, and ~11 μm respectively, imply the method’s ability to resolve individual neuronal sources. Similarly, source intensity estimation results indicate that this approach can accurately track changes in neuronal signal amplitude. Together, these results demonstrate the potential of the presented approach in characterizing neuronal signal sources in vivo, which may significantly improve the extracellular recording process and enable a more accurate interpretation of experimental data.

The immobilization of horseradish peroxidase (HRP) enzyme causes protections on catalytic activities in determination of H₂O₂. The rate of electron transfer from redox enzyme onto the electrode surface is an important topic in bioelectrochemistry that could improve more the function of HRP biosensor by means of increasing electrode conductivity. Referring to this basis, effect of various nanoparticles are evaluated and compared with each other on the operation promotion in this review and Glassy Carbon Electrode (GCE) is utilized as a main foundation on immobilization of nanoparticles and HRP enzyme. Electrodes have been compared by the rate of current transfer in the optimum voltage data in the presence of Carbon-coated Iron Nanoparticles (CIN), Quantum Dots (QDs), Au and Laponite/Chit nanoparticles. Consequently in the same scan rate, HRP/Au/GCE (28 μA) has achieved more current which is about 94% comparing to the base electrode HRP/GCE (1.8 μA).

We present a rapid (4-hr) electrical method for Antibiotic Susceptibility Testing that not only yields the MIC of candidate antibiotics, but also simultaneously determines the antibiotics’ effect on the bacteria (bactericidal/bacteriostatic). Unlike conventional “impedance microbiology” methods that rely on measuring the effects of bacterial metabolism on the conductance/impedance of the suspension at a single chosen frequency, our method uses measurements at 500 frequencies between 1 KHz and 100 MHz to estimate the amount of electric charge stored due to charge-polarization at intact cell-membranes of living bacteria (the suspension “bulk capacitance”). By doing so, we are able to track the number of live bacteria in suspensions as the observations are taken (every 1 hour). It thus determines whether the numbers of viable bacteria present is increasing (bacteria proliferating in presence of antibiotic), decreasing (bacteria being killed) or holding steady (bacterial numbers held static). Three well-characterized bacterial strains (E. coli ATCC- 25922, S. aureus ATCC-29213 and P. aeruginosa ATCC-27853) were tested against a range of concentrations (0 to 128 mg/l) of known static and cidal antibiotics. For each sample (bacterial strain at a given concentration of antibiotic), statistical analysis of the “bulk capacitance” values, recorded over 4 hours was used to determine whether the bacteria were proliferating, being killed, or being held static. The minimum concentration of antibiotic for which the bacteria were killed or failed to proliferate is considered the Minimum Inhibitory Concentration (MIC). MICs obtained fell within the expected range for the strains tested, and “static” and “cidal” antibiotics were correctly identified. This method thus demonstrates the potential to provide in 4 hrs, clinically relevant information such as the MIC of bacterial strains (that currently take up to 2 days) and the mode of action (static/cidal) that currently takes an additional day.

Background: Early diagnosis and treatment through mass screening is practical against colorectal cancer (CRC). Low compliance for current screening tests affects the effectiveness of CRC mass screening. An efficient screening protocol with high compliance is needed for CRC mass screening.
Methods: Systematic searches were done through Medline and Cochrane Library databases - initial Medline searches were in February 2010 and additional searches in March/April 2010. Search terms included [(“Colorectal cancer” AND “screening program” AND “incidence”) OR (“Colorectal cancer” AND “screening program” AND “mortality”)] AND [“fecal occult blood test” OR “sigmoidoscopy” OR “colonoscopy” OR “Double-contrast barium enema”].
Results: This review explored the current CRC mass screening protocols to find a more efficient and practical mass screening protocol and problems suitable for further research. Considering the current economic crisis and limited available resources, combination of high risk factor questionnaire and immunochemical fecal occult blood test approach as primary CRC mass screening can currently be used as a risk stratification tool to identify high-risk populations from the community, especially for medically and economically underserved areas/countries before a new better test comes. Using serum Pyruvate Kinase Isoenzyme M2 (M2-PK) as primary and colonoscopy as secondary screening test sounds more efficient with higher compliance than current CRC mass screening protocols.
Conclusion: Recommendations for CRC mass screening are suggested for each risk population based on risk stratification. Serum M2-PK- may be developed as a promising CRC primary mass screening test. Sequential combination of serum biomarker such as Pyruvate Kinase Isoenzyme M2 (M2-PK) and colonoscopy can be a promising CRC mass screening protocol.

Ductal carcinoma in situ (DCIS) is a heterogeneous disease characterized by noninvasive clonal proliferation of malignant epithelial cells arising from the mammary ducts and terminal ductal-lobular units. Its reported incidence is rising due to the wide adoption of screening mammography and magnetic resonance imaging (MRI). The combination of nuclear grade and presence of necrosis is currently the best predictor of biological behavior. DCIS should be managed in the context of a multidisciplinary team. Local control depends upon adequate surgical clearance with margins of
at least 2mm. Sentinel lymph node biopsy (SLNB) is not routinely indicated and should be reserved for those with concurrent or recurrent invasive disease. SLNB can be considered in patients undergoing mastectomy (MX) and those with risk factors for invasion such as palpability, comedo morphology, necrosis or recurrent disease. Radiotherapy (RT) following breast conserving surgery (BCS) significantly reduces local recurrence (LR), particularly in those at high-risk. There remains a lack of level-1 evidence supporting the omission of adjuvant RT in selected low risk cases. Large, multi-centric or recurrent lesions (particularly in cases of prior RT) should be treated by MX with the opportunity for immediate reconstruction. Adjuvant Tamoxifen may reduce the risk of LR in selected cases with hormone sensitive disease. Further research is required to determine the role of contemporary RT regimes and endocrine therapies. Biological profiling and molecular analysis represent an opportunity to improve our understanding of the tumour biology of this condition and rationalise its treatment. Reliable identification of low-risk lesions could allow treatment to be less radical or safely omitted.

The purpose of this study was to determine if a general motor program controlled some or all aspects of overhand throwing. Using a 12 camera Vicon motion analysis system to record data from body markers, a group of 30 Australian Aboriginal children 6-10 years of age threw with maximal effort into a large target area. Data were reduced and analyzed for numerous variables and correlations were calculated between dominant and non-dominant side variables that were deemed reliable. Results indicated that five variables showed significant dominant to non-dominant correlations. However, only two of the five were entered into both multiple regressions to predict horizontal ball velocity for the dominant vs. non-dominant sides. The variables entered suggested that more gross aspects of the movement (stride
distance and pelvis flexion) were both correlated from dominant to non-dominant sides and predicted horizontal ball velocity. Thus, the general motor program does not appear to control the more complex and coordinated parts of the throwing motion.