Ultra-low-power Physical Activity Classifier for Wearables: From Generic MCUs to ASICs.

In the era of Internet of Things (IoT), an increasing amount of sensors is being integrated into intelligent wearable devices. These sensors have the potential to produce a large quantity of physiological data streams to be analyzed in order to produce meaningful and actionable information. An important part of this processing is usually located in the device itself and takes the form of embedded algorithms which are executed into the onboard microcontroller (MCU). As data processing algorithms have become more complex due to, in part, the disruption of machine learning, they are taking an increasing part of MCU time becoming one of the main driving factors in the energy budget of the overall embedded system. We propose to integrate such algorithms into dedicated low-power circuits making the power consumption of the processing part negligible to the overall system. We provide the results of several implementations of a pre-trained physical activity classifier used in smartwatches and wristbands. The algorithm combines signal processing for feature extraction and machine learning in the form of decision trees for physical activity classification. We show how an in-silicon implementation decreases up to 0.1 µW the power consumption compared to 73 µW on a general-purpose ARM's Cortex-M0 MCU.

Quality control of rigid endoscopes: a comparative study between ScopeControl® and surgeons' evaluation.

BACKGROUND: In central sterile services departments (CSSD), the functionality of rigid endoscopes, which are complex and fragile reusable devices, is usually controlled visually and is considered a complex and subjective task. ScopeControl® was developed to provide an automated quality control of rigid endoscopes by measuring the value of six parameters: viewing angle (VA), field of view (FV), color correctness (CC), light transmission (LT), fibers transmission (FT), and focus (FC). The aim of the present study was to assess the ability of ScopeControl® to pre-emptively identify endoscope defects before the surgeon considers them as defective. METHODS: The same endoscope was evaluated by surgeons during surgery using a scoring scale as well as the CSSD staff using the ScopeControl® during reprocessing. The ScopeControl® categorized the endoscope into 3 groups: "passed," "in danger," and "failed." Correlations between the surgeon's evaluation and results of the ScopeControl® were calculated. RESULTS: One hundred sixty-six controls were carried out concerning 51 different endoscopes. According to the surgeon's evaluation, 78.9% and 80.7% of controls were considered as satisfactory for image and brightness quality, respectively. Results obtained using ScopeControl® found that 13.3% of controls were considered as "passed," 31.3% "in danger," and 55.4% "failed," with poor correlation with the surgeons' evaluation. LT and FT parameters represented 95.2% of the reasons for failures. The ability of the ScopeControl® to detect endoscope defects earlier than surgeons was validated by tracking the results of endoscopes used and controlled several times. CONCLUSION: The ScopeControl® achieved an objective and consistent quality control of endoscopes and showed poor correlation with the surgeon's opinion. In practice, the ScopeControl® could avoid the use of defective endoscopes in the surgery unit and thus improve the quality of the surgical procedure.

Change in Expression of 5-HT6 Receptor at Different Stages of Alzheimer's Disease: A Postmortem Study with the PET Radiopharmaceutical [18F]2FNQ1P.

BACKGROUND: The 5-HT6 receptor is one of the most recently identified serotonin receptors in the central nervous system. Because of its role in memory and cognitive process, this receptor might be implicated in Alzheimer's disease (AD) and associated disorders. OBJECTIVE: The aim of this study was to investigate the binding of [18F]2FNQ1P, a new specific radiotracer of 5-HT6 receptors, and to quantify 5-HT6 receptor density in caudate nucleus in a population of patients with different AD stages. METHODS: Patients were classified according to the "ABC" NIA-AA classification. In vitro binding assays were performed in postmortem brain tissue from the healthy control (HC; n = 8) and severe AD ("High"; n = 8) groups. In vitro quantitative autoradiography was performed in human brain tissue (caudate nucleus) from patients with different stages of AD: HC (n = 15), "Low" (n = 18), "Int" (n = 20), and "High" (n = 15). RESULTS: In vitro binding assays did not show significant differences for the KD and Bmax parameters between "High" and HC groups. In vitro quantitative autoradiography showed a significant difference between the "High" and HC groups (p = 0.0025). We also showed a progressive diminution in [18F]2FNQ1P specific binding, which parallels 5-HT6 receptors expression, according to increasing AD stage. Significant differences were observed between the HC group and all AD stages combined ("Low", "Intermediate", and "High") (p = 0.011). CONCLUSION: This study confirms the interest of investigating the role of 5-HT6 receptors in AD and related disorders. [18F]2FNQ1P demonstrated specific binding to 5-HT6 receptors.

Preclinical validation of [18F]2FNQ1P as a specific PET radiotracer of 5-HT6 receptors in rat, pig, non-human primate and human brain tissue.

INTRODUCTION: The aim of this study was to perform in-vitro and in-vivo radiopharmacological characterizations of [18F]2FNQ1P, a new PET radiotracer of 5-HT6 receptors, in rat, pig, non-human primate and human tissues. The 5-HT6 receptor is one of the more recently identified serotonin receptors in central nervous system and, because of its role in memory and cognitive processes, is considered as a promising therapeutic target. METHODS: In-vitro autoradiography and saturation binding assays were performed in postmortem brain tissues from rat, pig, non-human primate and human caudate nucleus, completed by serum stability assessment in all species and cerebral radiometabolite and biodistribution studies in rat. RESULTS: In all species, autoradiography data revealed high binding levels of [18F]2FNQ1P in cerebral regions with high 5-HT6 receptor density. Binding was blocked by addition of SB258585 as a specific antagonist. Binding assays provided KD and Bmax values of respectively 1.34 nM and 0.03 pmol·mg-1 in rat, 0.60 nM and 0.04 pmol·mg-1 in pig, 1.38 nM and 0.07 pmol·mg-1 in non-human primate, and 1.39 nM and 0.15 pmol·mg-1 in human caudate nucleus. In rat brain, the proportion of unmetabolized [18F]2FNQ1P was >99% 5 min after iv injection and 89% at 40 min. The biodistribution studies found maximal radioactivity in lungs and kidneys (3.5 ± 1.2% ID/g and 2.0 ± 0.7% ID/g, respectively, 15 min post-injection). CONCLUSION: These radiopharmacological data confirm that [18F]2FNQ1P is a specific radiotracer for molecular imaging of 5-HT6 receptors and suggest that it could be used as a radiopharmaceutical in humans.

Serotonin 5-HT1A Receptor Biased Agonists Induce Different Cerebral Metabolic Responses: A [18F]-Fluorodesoxyglucose Positron Emission Tomography Study in Conscious and Anesthetized Rats.

Serotonin 5-HT1A receptors constitute an attractive therapeutic target for various psychiatric or neurodegenerative disorders. These receptors are expressed in multiple brain regions on different neuronal populations and can be coupled with distinct G-protein subtypes; such functional diversity complicates the use of 5-HT1A ligands in several pathologies where it would be desirable to stimulate the receptors in a precise region. Therefore, using "biased agonists" able to target specifically certain subpopulations of 5-HT1A receptors would enable achievement of better therapeutic benefit. Several 5-HT1A receptor biased agonists are currently in development, including NLX-101 (aka F15599) and NLX-112 (aka F13640, befiradol), with preclinical data suggesting that they preferentially target different populations of 5-HT1A receptors. However, most previous studies used invasive and regionally limited approaches. In this context, [18F]-fluorodesoxyglucose (FDG)-positron emission tomography (PET) imaging constitutes an interesting technique as it enables noninvasive mapping of the regional brain activity changes following a pharmacological challenge in conscious animals. We report here the evaluation of cerebral glucose metabolism following intraperitoneal injection of different doses of NLX-112 or NLX-101 in conscious or isoflurane-anesthetized rats. The biased agonists produced different metabolic "fingerprints" with distinct regional preferences, consistent with previous studies. At equal doses, the effect of NLX-101 was less marked than NLX-112 in the piriform cortex, in the striatum (in terms of inhibition), and in the pontine nuclei and the cerebellum (in terms of activation); furthermore, only NLX-112 increased the glucose metabolism in the parietal cortex, whereas only NLX-101 induced a clear activation in the colliculi and the frontal cortex, which may be related to its distinctive procognitive profile. Both agonist effects were almost completely unapparent in anesthetized animals, underlining the importance of studying serotonergic neurotransmission in the conscious state. In this regard, [18F]FDG-PET imaging seems very complementary with other functional imaging techniques such as pharmacological MRI.

Fractionated elution of 99Mo/99mTc generators using calibrated vials.

Fractionated elution consists in collecting the fractions of an eluate with the highest radioactive concentration. It may be useful to meet the requirements of a subset of clinical radiopharmacy procedures. This study aims to describe and evaluate straightforward procedures allowing to readily perform fractionated elution on dry and wet columns Mo/Tc generators by using calibrated vials. The main objectives of this study consisted in determining the relationship between eluate volume and elution yield using different vials calibration and assessing repeatability of the procedure. Elution vials were calibrated to obtain different eluate volumes by addition of air for wet column generator (WCG) and subtraction of saline for dry column generator (DCG) (n≥5 for each calibration). The relationship between the eluate volume and the elution yield was determined by a regression model for both DCG and WCG. Then repeatability evaluation was performed using 3-ml vial calibration. Relationships between the eluate volume (V) and the elution yield (Y) for DCG and WCG were Y=57.551 ln(V)+10.526 and Y=50.256 ln(V)+17.597, respectively. For repeatability assessment (n=30 for DCG and n=31 for WCG), the median volume and the interquartile range for DCG and WCG were 2.98 ml (2.92-3.01) and 3.28 ml (2.71-3.40), respectively, and median (interquartile range) eluate yields were 84.73% (81.30-86.33) and 81.78% (78.91-85.20), respectively. The volume was significantly higher for WCG than DCG (P=0.036) and also significantly more variable (P<0.001). The elution yield was significantly lower for WCG than DCG (P=0.025), but no difference in variability between the two generators was found (P=0.874). Easy-to-handle fractionated elution methods are compatible with both DCG and WCG. Fractionation using calibrated vials exhibits a better reproducibility with DCG than WCG generators and represents the only proposed method so far to master fractionated elution with DCG.