Point-of-care analyte quantification and digital readout via lysate-based cell-free biosensors interfaced with personal glucose monitors

Field-deployable diagnostics based on cell-free systems have advanced greatly, but on-site quantification of target analytes remains a challenge. Here we demonstrate that Escherichia coli lysate-based cell-free biosensors coupled to a personal glucose monitor (PGM) can enable on-site analyte quantification, with the potential for straightforward reconfigurability to diverse types of analytes. We show that analyte-responsive regulators of transcription and translation can modulate production of the reporter enzyme β-galactosidase, which in turn converts lactose into glucose for PGM quantification. Because glycolysis is active in the lysate and would readily deplete converted glucose, we decoupled enzyme production and glucose conversion to increase endpoint signal output. This lysate metabolism did, however, allow for one-pot removal of glucose present in complex samples (like human serum) without confounding target quantification. Taken together, we show that integrating lysate-based cell-free biosensors with PGMs enables accessible target detection and quantification at the point of need.

Design and system evaluation of a dual-panel portable PET (DP-PET)

Background Integrated whole-body PET/MR technology continues to mature and is now extensively used in clinical settings. However, due to the special design architecture, integrated whole-body PET/MR comes with a few inherent limitations. Firstly, whole-body PET/MR lacks sensitivity and resolution for focused organs. Secondly, broader clinical access of integrated PET/MR has been significantly restricted due to its prohibitively high cost. The MR-compatible PET insert is an independent and removable PET scanner which can be placed within an MRI bore. However, the mobility and configurability of all existing MR-compatible PET insert prototypes remain limited. Methods An MR-compatible portable PET insert prototype, dual-panel portable PET (DP-PET), has been developed for simultaneous PET/MR imaging. Using SiPM, digital readout electronics, novel carbon fiber shielding, phase-change cooling, and MRI compatible battery power, DP-PET was designed to achieve high-sensitivity and high-resolution with compatibility with a clinical 3-T MRI scanner. A GPU-based reconstruction method with resolution modeling (RM) has been developed for the DP-PET reconstruction. We evaluated the system performance on PET resolution, sensitivity, image quality, and the PET/MR interference. Results The initial results reveal that the DP-PET prototype worked as expected in the MRI bore and caused minimal compromise to the MRI image quality. The PET performance was measured to show a spatial resolution ≤ 2.5 mm (parallel to the detector panels), maximum sensitivity = 3.6% at the center of FOV, and energy resolution = 12.43%. MR pulsing introduces less than 2% variation to the PET performance measurement results. Conclusions We developed a MR-compatible PET insert prototype and performed several studies to begin to characterize the performance of the proposed DP-PET. The results showed that the proposed DP-PET performed well in the MRI bore and would cause little influence on the MRI images. The Derenzo phantom test showed that the proposed reconstruction method could obtain high-quality images using DP-PET.

Design and System Evaluation of a Dual-Panel Portable PET (DP-PET)

Background: Integrated whole-body PET/MR technology continues to mature and is now extensively used in clinical setting. However, due to the special design architecture, integrated whole-body PET/MR comes with a few inherent limitations. Firstly, whole-body PET/MR lacks sensitivity and resolution for focused organs. Secondly, boarder clinical access of integrated PET/MR has been significantly restricted due to its prohibitively high cost. The MR-compatible PET insert is a low cost and flexible PET scanner which can be placed within an MRI bore. However, mobility and configurability of all existing MR-compatible PET insert prototypes remain limited. Methods: An MR-compatible portable PET insert prototype, Dual-panel Portable PET (DP-PET), has been developed for simultaneous PET/MR imaging. Using SiPM, digital readout electronics, novel carbon fiber shielding, phase-change cooling and MRI compatible battery power, DP-PET was designed to achieve high-sensitivity and high-resolution with compatibility with a clinical 3T MRI scanner. A GPU-based reconstruction method with Resolution Modelling (RM) has been developed for the DP-PET reconstruction. We evaluated the system performance on PET resolution, sensitivity, image quality and the PET/MR interference. Results: Initial results reveal that the DP-PET prototype worked as expected in the MRI bore and caused minimal compromise to the MRI image quality. The PET performance was measured to show a spatial resolution <= 2mm (parallel to the detector panels), maximum sensitivity =3.6% at the center of FOV and energy resolution = 12.43%. MRI pulsing introduces less than 1% variation to the PET performance measurement results. Conclusions: We developed a MR-compatible PET insert prototype and performed several studies to begin to characterize the performance of the proposed DP-PET.The results showed that the proposed DP-PET performed well in the MRI bore and would cause little influence on the MRI images. The Derenzo phantom test showed that the proposed reconstruction method could obtained high quality images using DP-PET.

NanoString Technology for Human Papillomavirus Typing

High-throughput HPV typing assays with increased automation, faster turnaround and type-specific digital readout would facilitate studies monitoring the impact of HPV vaccination. We evaluated the NanoString nCounter® platform for detection and digital readout of 48 HPV types in a single reaction. NanoString (NS) used proprietary software to design CodeSets: type-specific probe pairs targeting 48 HPV types and the globin gene. We tested residual DNA extracts from epidemiologic specimens and defined samples (HPV plasmids at 10 to 104 copies/reaction) directly (No-PCR) as well as after L1 consensus PCR of 45 (PCR-45) or 15 cycles (PCR-15). Assay and interpretation followed NS recommendations. We evaluated analytic performance by comparing NanoString results for types included in prior assays: Roche Linear Array (LA) or HPV TypeSeq assay. No-PCR results on 40 samples showed good type-specific agreement with LA (k = 0.621) but sensitivity was 65% with lower limit of detection (LOD) at 104 plasmid copies. PCR-45 results showed almost perfect type-specific agreement with LA (k = 0.862), 82% sensitivity and LOD at 10 copies. PCR-15 results on 75 samples showed substantial type-specific agreement with LA (k = 0.796, 92% sensitivity) and TypeSeq (k = 0.777, 87% sensitivity), and LOD at 10 copies of plasmids. This proof-of-principle study demonstrates the efficacy of the NS platform with HPV CodeSet for type-specific detection using a low number of PCR cycles (PCR-15). Studies are in progress to evaluate assay reproducibility and analytic validation with a larger number of samples.

Justification of requirements for digital signal synthesizers for various types of radar

В работе обосновываются требования к уровню искажений радиолокационных станций с импульсным и квазинепрерывным излучением, построенных на основе цифровых синтезаторов сигналов четырех типов: цифровых синтезаторах отсчетов напряжения и цифровых синтезаторах отсчетов фазы с равномерной дискретизацией, цифровых синтезаторах отсчетов напряжения и цифровых синтезаторах отсчетов фазы с неравномерной дискретизацией. При построении задающего устройства РЛС возникает вопрос о выборе типа цифрового синтезатора сигналов. Основными исходными критериями при этом являются максимальный рабочий диапазон цифрового синтезатора и уровень внутриполосных искажений. При выборе типа цифрового синтезатора сигналов необходимо учитывать большое количество факторов, основными из которых являются сложность исполнения формирователя цифровых отсчетов, возможность реализации формирователя цифровых отсчетов с требуемым быстродействием и количеством разрядов [1, 2]. При предъявлении требований к суммарному уровню искажений используется критерий допустимого снижения вероятности правильного обнаружения по сравнению с её потенциальным значением при фиксированной вероятности ложной тревоги. Исходя из данного критерия в импульсных РЛС максимальное относительное среднеквадратическое значение искажений взаимокорреляционной функции сигнала с угловой модуляцией, формируемого цифровым синтезатором, не должно превышать $D_{\\delta x}\\le $-(51...67) дБ. В РЛС с квазинепрерывным излучением максимальное относительное среднеквадратическое значение искажений автокорреляционной функции сигнала с угловой модуляцией не должно превышать $D_{\\delta }\\le $-(80...120) дБ. Количество разрядов квантования фазы, напряжения и компенсации временной задержки в цифровых синтезаторах сигналов зависит не только от максимального относительного среднеквадратического значения искажений взаимокорреляционной функции но и от количества отсчетов сигнала с угловой модуляцией. Поэтому первоначально необходимо выбрать эталонную частоту цифрового синтезатора сигналов, задаваясь видом модуляции и эффективной шириной спектра сигнала с угловой модуляцией исходя из ТТХ РЛС. The paper substantiates the requirements for the level of distortion of radar stations with pulsed and quasi-continuous radiation, built on the basis of digital signal synthesizers of four types: digital synthesizers of voltage counts and digital synthesizers of phase counts with uniform sampling, digital synthesizers of voltage counts and digital synthesizers of phase counts with uneven sampling. When building a radar master device, the question arises about choosing the type of digital signal synthesizer. The main initial criteria are the maximum operating range of the digital synthesizer and the level of in-band distortion. When choosing the type of digital signal synthesizer, you must take into account a large number of factors, the main of which are the complexity of the execution of the digital readout shaper, the possibility of implementing a digital readout shaper with the required speed and number of digits [1, 2]. When making requirements for the total level of distortion, the criterion of acceptable reduction of the probability of correct detection in comparison with its potential value for a fixed probability of false alarm is used. Based on this criterion, in pulse radars, the maximum relative RMS value of the distortion of the intercorrelation function of a signal with angular modulation generated by a digital synthesizer should not exceed $D_{\\delta x}\\le $-(51...67) dB. In a radar with quasi-continuous radiation, the maximum relative mean-square value of the distortion of the autocorrelation function of the signal with angular modulation should not exceed $D_{\\delta }\\le $- (80...120) dB. The number of bits of phase quantization, voltage and time delay compensation in digital signal synthesizers depends not only on the maximum relative RMS value of the distortion of the intercorrelation function, but also on the number of samples of the signal with angular modulation. Therefore, initially you need to select the reference frequency of the digital signal synthesizer, setting the type of modulation and the effective spectrum width of the signal with angular modulation based on the tactical and technical characteristics radar.