57 research outputs found

    High-resolution, high-contrast ultrasound imaging using a prototype dual-frequency transducer: In vitro and in vivo studies

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    With recent advances in animal models of disease, there has been great interest in capabilities for high-resolution contrast-enhanced ultrasound imaging. Microbubble contrast agents are unique in that they scatter broadband ultrasound energy because of their nonlinear behavior. For optimal response, it is desirable to excite the microbubbles near their resonant frequency. To date, this has been challenging with high-frequency imaging systems because most contrast agents are resonant at frequencies in the order of several megahertz. Our team has developed a unique dual-frequency confocal transducer which enables low-frequency excitation of bubbles near their resonance with one element, and detection of their emitted high-frequency content with the second element. Using this imaging approach, we have attained an average 12.3 dB improvement in contrast-to-tissue ratios over fundamental mode imaging, with spatial resolution near that of the high-frequency element. Because this detection method does not rely on signal decorrelation, it is not susceptible to corruption by tissue motion. This probe demonstrates contrast imaging capability with significant tissue suppression, enabling high-resolution contrast-enhanced images of microvascular blood flow. Additionally, this probe can readily produce radiation force on flowing contrast agents, which may be beneficial for targeted imaging or therapy

    Post-Construction Support and Sustainability in Community-Managed Rural Water Supply

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    Executive Summary This volume reports the main findings from a multi-country research project that was designed to develop a better understanding of how rural water supply systems are performing in developing countries. We began the research in 2004 to investigate how the provision of support to communities after the construction of a rural water supply project affected project performance in the medium term. We collected information from households, village water committees, focus groups of village residents, system operators, and key informants in 400 rural communities in Bolivia, Ghana, and Peru; in total, we discussed community water supply issues with approximately 10,000 individuals in these communities. To our surprise, we found the great majority of the village water systems were performing well. Our findings on the factors influencing their sustainability will, we hope, be of use to policy makers, investors, and managers in rural water supply

    A highly compact packaging concept for ultrasound transducer arrays embedded in neurosurgical needles

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    State-of-the-art neurosurgery intervention relies heavily on information from tissue imaging taken at a pre-operative stage. However, the data retrieved prior to performing an opening in the patient’s skull may present inconsistencies with respect to the tissue position observed by the surgeon during intervention, due to both the pulsing vasculature and possible displacements of the brain. The consequent uncertainty of the actual tissue position during the insertion of surgical tools has resulted in great interest in real-time guidance techniques. Ultrasound guidance during neurosurgery is a promising method for imaging the tissue while inserting surgical tools, as it may provide high resolution images. Microfabrication techniques have enabled the miniaturisation of ultrasound arrays to fit needle gauges below 2 mm inner diameter. However, the integration of array transducers in surgical needles requires the development of advanced interconnection techniques that can provide an interface between the microscale array elements and the macroscale connectors to the driving electronics. This paper presents progress towards a novel packaging scheme that uses a thin flexible printed circuit board (PCB) wound inside a surgical needle. The flexible PCB is connected to a probe at the tip of the needle by means of magnetically aligned anisotropic conductive paste. This bonding technology offers higher compactness compared to conventional wire bonding, as the individual electrical connections are isolated from one another within the volume of the paste line, and applies a reduced thermal load compared to thermo-compression or eutectic packaging techniques. The reduction in the volume required for the interconnection allows for denser wiring of ultrasound probes within interventional tools. This allows the integration of arrays with higher element counts in confined packages, potentially enabling multi-modality imaging with Raman, OCT, and impediography. Promising experimental results and a prototype needle assembly are presented to demonstrate the viability of the proposed packaging scheme. The progress reported in this work are steps towards the production of fully-functional imaging-enabled needles that can be used as surgical guidance tools

    Распространенность болезни Помпе у пациентов с идиопатической гиперкреатинкиназемией и слабостью поясно-конечностных мышц (анализ 3076 случаев)*

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    .Проведен проспективный скрининг дефицита фермента кислой α-глюкозидазы (GAA) европейской когорты пациентов с гиперкреатинкиназемией (гиперКК) и / или слабостью поясно-конечностных мышц (СПКМ) неустановленной этиологии с помощью метода сухого пятна крови (dry blood spot, DBS).Материалы и методы. Образцы DBS были собраны у 3076 взрослых пациентов, проходивших обследование в 7 немецких и британских нервно-мышечных центрах. Все образцы были исследованы на дефицит GAA методом флуорометрии. При выявлении пониженной ферментативной активности определяли наличие мутации гена GAA.Результаты. Из 3076 образцов DBS в 232 (7,6 %) случаях обнаружена низкая ферментативная активность GAA. У 55 (24 %) из 232 пациентов наблюдали изолированную гиперКК, а у 176 (76 %) – гиперКК и СПКМ. При комбинации 2 признаков у 94 % больных активность GAA была снижена. Мутационный анализ выявил мутации гена GAA у 74 (2,4 %) пациентов, при этом 70 больных были гетерозиготными по распространенной мутации сайта сплайсинга гена GAA c.-32-13T>G. У пациентов с подтвержденной болезнью Помпе основной симптомокомплекс состоял из СПКМ (85,3 %) в сочетании с дыхательной недостаточностью (61 %). У 12,0 % больных наблюдали изолированную гиперКК, а у 2,7 % – гиперКК и дыхательную недостаточность.Заключение. В большой когорте пациентов с гиперКК и / или СПКМ  распространенность болезни Помпе с поздним началом составляет 2,4 %, что требует проведения целевого скрининга активности GAA у пациентов с гиперКК и / или СПКМнеустановленной этиологии

    AI is a viable alternative to high throughput screening: a 318-target study

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    : High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

    Low prevalence estimates of late-onset glycogen storage disease type II in French-speaking Belgium are not due to missed diagnoses

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    Background: Late-onset glycogen storage disease type II is associated with variable muscle phenotypes. Epidemiological data suggest that its prevalence is lower in Belgium than in bordering countries like The Netherlands. Objective: We investigated whether such low estimated prevalence is due to missed diagnoses. Methods: We screened 100 patients with muscle phenotypes of undetermined origin using a dried blood spot test for alpha-acid glucosidase (GAA) activity. Patients with low activity at screening were re-tested by the same method and, if low activity was confirmed, GAA gene analysis was performed. Results: The screening test revealed lower than normal GAA activity in 15 patients, but in only two of them it was low enough to be considered in the disease range. Retesting confirmed lower than normal GAA activity in five patients, but in all of them it was above the disease range. A single patient carried a heterozygous known pathogenic GAA mutation, whose significance in this case remains undetermined. Conclusions: We conclude that reported low prevalence estimates in Belgium are not likely to be due to an underdiagnosis bias. Lower prevalence compared to neighbouring The Netherlands may be due to different ethnic stratification of our patients. Diagnostic strategies should keep into account the expected prevalence of a disease in specific populations.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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