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1.
J Med Internet Res ; 26: e45904, 2024 Mar 06.
Article in English | MEDLINE | ID: mdl-38446500

ABSTRACT

BACKGROUND: Smartphone apps can aid consumers in making healthier and more sustainable food purchases. However, there is still a limited understanding of the different app design approaches and their impact on food purchase choices. An overview of existing food purchase choice apps and an understanding of common challenges can help speed up effective future developments. OBJECTIVE: We examined the academic literature on food purchase choice apps and provided an overview of the design characteristics, opportunities, and challenges for effective implementation. Thus, we contribute to an understanding of how technologies can effectively improve food purchase choice behavior and provide recommendations for future design efforts. METHODS: Following the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines, we considered peer-reviewed literature on food purchase choice apps within IEEE Xplore, PubMed, Scopus, and ScienceDirect. We inductively coded and summarized design characteristics. Opportunities and challenges were addressed from both quantitative and qualitative perspectives. From the quantitative perspective, we coded and summarized outcomes of comparative evaluation trials. From the qualitative perspective, we performed a qualitative content analysis of commonly discussed opportunities and challenges. RESULTS: We retrieved 55 articles, identified 46 unique apps, and grouped them into 5 distinct app types. Each app type supports a specific purchase choice stage and shares a common functional design. Most apps support the product selection stage (selection apps; 27/46, 59%), commonly by scanning the barcode and displaying a nutritional rating. In total, 73% (8/11) of the evaluation trials reported significant findings and indicated the potential of food purchase choice apps to support behavior change. However, relatively few evaluations covered the selection app type, and these studies showed mixed results. We found a common opportunity in apps contributing to learning (knowledge gain), whereas infrequent engagement presents a common challenge. The latter was associated with perceived burden of use, trust, and performance as well as with learning. In addition, there were technical challenges in establishing comprehensive product information databases or achieving performance accuracy with advanced identification methods such as image recognition. CONCLUSIONS: Our findings suggest that designs of food purchase choice apps do not encourage repeated use or long-term adoption, compromising the effectiveness of behavior change through nudging. However, we found that smartphone apps can enhance learning, which plays an important role in behavior change. Compared with nudging as a mechanism for behavior change, this mechanism is less dependent on continued use. We argue that designs that optimize for learning within each interaction have a better chance of achieving behavior change. This review concludes with design recommendations, suggesting that food purchase choice app designers anticipate the possibility of early abandonment as part of their design process and design apps that optimize the learning experience.


Subject(s)
Mobile Applications , Humans , Food , Learning , Databases, Factual , Health Status
3.
J Physiol ; 601(24): 5795-5811, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37983193

ABSTRACT

Inspiratory tongue dilatory movement is believed to be mediated via changes in neural drive to genioglossus. However, this has not been studied during quiet breathing in humans. Therefore, this study investigated this relationship and its potential role in obstructive sleep apnoea (OSA). During awake supine quiet nasal breathing, inspiratory tongue dilatory movement, quantified with tagged magnetic resonance imaging, and inspiratory phasic genioglossus EMG normalised to maximum EMG were measured in nine controls [apnoea-hypopnea index (AHI) ≤5 events/h] and 37 people with untreated OSA (AHI >5 events/h). Measurements were obtained for 156 neuromuscular compartments (85%). Analysis was adjusted for nadir epiglottic pressure during inspiration. Only for 106 compartments (68%) was a larger anterior (dilatory) movement associated with a higher phasic EMG [mixed linear regression, beta = 0.089, 95% CI [0.000, 0.178], t(99) = 1.995, P = 0.049, hereafter EMG↗/mvt↗]. For the remaining 50 (32%) compartments, a larger dilatory movement was associated with a lower phasic EMG [mixed linear regression, beta = -0.123, 95% CI [-0.224, -0.022], t(43) = -2.458, P = 0.018, hereafter EMG↘/mvt↗]. OSA participants had a higher odds of having at least one decoupled EMG↘/mvt↗ compartment (binary logistic regression, odds ratio [95% CI]: 7.53 [1.19, 47.47] (P = 0.032). Dilatory tongue movement was minimal (>1 mm) in nearly all participants with only EMG↗/mvt↗ compartments (86%, 18/21). These results demonstrate that upper airway dilatory mechanics cannot be predicted from genioglossus EMG, particularly in people with OSA. Tongue movement associated with minimal genioglossus activity suggests co-activation of other airway dilator muscles. KEY POINTS: Inspiratory tongue movement is thought to be mediated through changes in genioglossus activity. However, it is unknown if this relationship is altered by obstructive sleep apnoea (OSA). During awake supine quiet nasal breathing, inspiratory tongue movement, quantified with tagged magnetic resonance imaging (MRI), and inspiratory phasic genioglossus EMG normalised to maximum EMG were measured in four tongue compartments of people with and without OSA. Larger tongue anterior (dilatory) movement was associated with higher phasic genioglossus EMG for 68% of compartments. OSA participants had an ∼7-times higher odds of having at least one compartment for which a larger anterior tongue movement was not associated with a higher phasic EMG than controls. Therefore, higher genioglossus phasic EMG does not consistently translate into tongue dilatory movement, particularly in people with OSA. Large dilatory tongue movements can occur despite minimal genioglossus inspiratory activity, suggesting co-activation of other pharyngeal muscles.


Subject(s)
Sleep Apnea, Obstructive , Wakefulness , Humans , Wakefulness/physiology , Pharyngeal Muscles , Movement/physiology , Tongue , Electromyography
4.
Digit Biomark ; 7(1): 132-138, 2023.
Article in English | MEDLINE | ID: mdl-37901363

ABSTRACT

Background: Innovative Medicines Initiative (IMI) consortium IDEA-FAST is developing novel digital measures of fatigue, sleep quality, and impact of sleep disturbances for neurodegenerative diseases and immune-mediated inflammatory diseases. In 2022, the consortium met with the European Medicines Agency (EMA) to receive advice on its plans for regulatory qualification of the measures. This viewpoint reviews the IDEA-FAST perspective on developing digital measures for multiple diseases and the advice provided by the EMA. Summary: The EMA considered a cross-disease measure an interesting and arguably feasible concept. Developers should account for the need for a strong rationale that the clinical features to be measured are similar across diseases. In addition, they may expect increased complexity of study design, challenges when managing differences within and between disease populations, and the need for validation in both heterogeneous and homogeneous populations. Key Messages: EMA highlighted the challenges teams may encounter when developing a cross-disease measure, though benefits potentially include reduced resources for the technology developer and health authority, faster access to innovation across different therapeutic fields, and feasibility of cross-disease comparisons. The insights included here can be used by project teams to guide them in the development of cross-disease digital measures intended for regulatory qualification.

5.
Digit Health ; 9: 20552076231181239, 2023.
Article in English | MEDLINE | ID: mdl-37361435

ABSTRACT

Objective: Digital devices have demonstrated benefits to patients with chronic and neurodegenerative diseases. But when patients use medical devices in their homes, the technologies have to fit into their lives. We investigated the technology acceptance of seven digital devices for home use. Methods: We conducted 60 semi-structured interviews with participants of a larger device study on their views on the acceptability of seven devices. Transcriptions were analysed using qualitative content analysis. Results: Based on the unified theory of acceptance and use of technology, we evaluated effort, facilitating conditions, performance expectancy and social influence of each device.In the effort category, five themes emerged: (a) the hassle to use the device; (b) its usability; (c) comfort; (d) disturbance to daily life; and (e) problems during usage. Facilitating conditions consisted of five themes: (a) expectations regarding a device; (b) quality of the instructions; (c) insecurities with usage; (d) possibilities of optimization; and (e) possibilities to use the device longer. Regarding performance expectancy, we identified three themes: (a) insecurities with the performance of a device; (b) feedback; and (c) motivation for using a device. In the social influence category, three themes emerged: (a) reactions of peers; (b) concerns with the visibility of a device; and (c) concerns regarding data privacy. Conclusions: We identify key factors that determine the acceptability of medical devices for home use from the participants' perspective. These include low effort of use, minor disruptions to their daily lives and good support from the study team.

6.
Digit Biomark ; 7(1): 28-44, 2023.
Article in English | MEDLINE | ID: mdl-37206894

ABSTRACT

Background: Digital measures offer an unparalleled opportunity to create a more holistic picture of how people who are patients behave in their real-world environments, thereby establishing a better connection between patients, caregivers, and the clinical evidence used to drive drug development and disease management. Reaching this vision will require achieving a new level of co-creation between the stakeholders who design, develop, use, and make decisions using evidence from digital measures. Summary: In September 2022, the second in a series of meetings hosted by the Swiss Federal Institute of Technology in Zürich, the Foundation for the National Institutes of Health Biomarkers Consortium, and sponsored by Wellcome Trust, entitled "Reverse Engineering of Digital Measures," was held in Zurich, Switzerland, with a broad range of stakeholders sharing their experience across four case studies to examine how patient centricity is essential in shaping development and validation of digital evidence generation tools. Key Messages: In this paper, we discuss progress and the remaining barriers to widespread use of digital measures for evidence generation in clinical development and care delivery. We also present key discussion points and takeaways in order to continue discourse and provide a basis for dissemination and outreach to the wider community and other stakeholders. The work presented here shows us a blueprint for how and why the patient voice can be thoughtfully integrated into digital measure development and that continued multistakeholder engagement is critical for further progress.

7.
Aging Ment Health ; 27(1): 193-202, 2023 01.
Article in English | MEDLINE | ID: mdl-35352597

ABSTRACT

OBJECTIVES: Computer-use behaviours can provide useful information about an individual's cognitive and functional abilities. However, little research has evaluated unaided and non-directed home computer-use. In this proof of principle study, we explored whether computer-use behaviours recorded during routine home computer-use i) could discriminate between individuals with subjective cognitive decline (SCD) and individuals with mild cognitive impairment (MCI); ii) were associated with cognitive and functional scores; and iii) changed over time. METHODS: Thirty-two participants with SCD (n = 18) or MCI (n = 14) (mean age = 72.53 years; female n = 19) participated in a longitudinal study in which their in-home computer-use behaviour was passively recorded over 7-9 months. Cognitive and functional assessments were completed at three time points: baseline; mid-point (4.5 months); and end point (month 7 to 9). RESULTS: Individuals with MCI had significantly slower keystroke speed and spent less time on the computer than individuals with SCD. More time spent on the computer was associated with better task switching abilities. Faster keystroke speed was associated with better visual attention, recall, recognition, task inhibition, and task switching. No significant change in computer-use behaviour was detected over the study period. CONCLUSION: Passive monitoring of computer-use behaviour shows potential as an indicator of cognitive abilities, and can differentiate between people with SCD and MCI. Future studies should attempt to monitor computer-use behaviours over a longer time period to capture the onset of cognitive decline, and thus could inform timely therapeutic interventions.Supplemental data for this article can be accessed online at http://dx.doi.org/10.1080/13607863.2022.2036946.


Subject(s)
Cognitive Dysfunction , Humans , Female , Aged , Male , Longitudinal Studies , Cognition , Recognition, Psychology , Computers , Neuropsychological Tests
8.
Sci Adv ; 8(47): eadd0720, 2022 Nov 25.
Article in English | MEDLINE | ID: mdl-36417533

ABSTRACT

Ocean mixing around Antarctica exerts key influences on glacier dynamics and ice shelf retreats, sea ice, and marine productivity, thus affecting global sea level and climate. The conventional paradigm is that this is dominated by winds, tides, and buoyancy forcing. Direct observations from the Antarctic Peninsula demonstrate that glacier calving triggers internal tsunamis, the breaking of which drives vigorous mixing. Being widespread and frequent, these internal tsunamis are at least comparable to winds, and much more important than tides, in driving regional shelf mixing. They are likely relevant everywhere that marine-terminating glaciers calve, including Greenland and across the Arctic. Calving frequency may change with higher ocean temperatures, suggesting possible shifts to internal tsunamigenesis and mixing in a warming climate.

9.
Dement Geriatr Cogn Disord ; 47(3): 157-163, 2019.
Article in English | MEDLINE | ID: mdl-31247628

ABSTRACT

BACKGROUND: People have various and changing needs as they age, and the number of people living with some form of dementia is steadily increasing. Smart homes have a unique potential to provide assisted living but are often designed rigidly with a specific and fixed problem in mind. OBJECTIVES: To make smart-ready homes and communities that can be adaptively and easily updated over time to support varying user needs and to deliver the needed assistance, empowerment, and living independence. METHOD: The design and deployment of programmable assistive environment for older adults. RESULTS: The use of platform technology (a special form of what is known today as the Internet of Things or IoT) has enabled the decoupling of goal setting and application development from sensing and assistive technology deployment and insertion in the assistive environment. Personalising a smart home or changing its applications and its interfaces dynamically as the user needs change was possible and has been demonstrated successfully in one house - the Gator Tech Smart House. Scaling up the platform technology approach to a planned living community is underway at one of UK's National Health Services (NHS) Healthy New Town projects. CONCLUSIONS: There is a great need to integrate technology with living spaces to provide assistance and independent living, but to smarten these spaces for lifelong living, the technology and the smart home applications must be flexible, adaptive, and changeable over time. However, people do not just live at home, they live in communities. Looking at the big picture (communities), as well as the small (homes), we consider how to progress beyond smart-ready homes towards smart-ready communities.


Subject(s)
Assisted Living Facilities/organization & administration , Dementia/therapy , Self-Help Devices/trends , Alzheimer Disease/psychology , Alzheimer Disease/therapy , Delivery of Health Care , Humans , Independent Living , State Medicine , United Kingdom
10.
Neuron ; 84(6): 1170-82, 2014 Dec 17.
Article in English | MEDLINE | ID: mdl-25482026

ABSTRACT

Brain recordings in large animal models and humans typically rely on a tethered connection, which has restricted the spectrum of accessible experimental and clinical applications. To overcome this limitation, we have engineered a compact, lightweight, high data rate wireless neurosensor capable of recording the full spectrum of electrophysiological signals from the cortex of mobile subjects. The wireless communication system exploits a spatially distributed network of synchronized receivers that is scalable to hundreds of channels and vast environments. To demonstrate the versatility of our wireless neurosensor, we monitored cortical neuron populations in freely behaving nonhuman primates during natural locomotion and sleep-wake transitions in ecologically equivalent settings. The interface is electrically safe and compatible with the majority of existing neural probes, which may support previously inaccessible experimental and clinical research.


Subject(s)
Electrodes, Implanted , Electrophysiology/instrumentation , Telemetry/instrumentation , Animals , Cerebral Cortex/physiology , Electrophysiology/methods , Macaca mulatta , Male , Neurons/physiology , Sleep/physiology , Telemetry/methods , Wakefulness/physiology , Walking/physiology
11.
BMC Microbiol ; 14: 196, 2014 Aug 01.
Article in English | MEDLINE | ID: mdl-25085267

ABSTRACT

BACKGROUND: The current inability to culture the entirety of observed bacteria is well known and with the advent of ever more powerful molecular tools, that can survey bacterial communities at previously unattainable depth, the gap in our capacity to culture and define all of these species increases exponentially. This gap has essentially become the rate limiting step in determining how the knowledge of which species are present in a sample can be applied to understand the role of these species in an ecosystem or disease process. A case in point is periodontal disease, which is the most widespread oral disease in dogs. If untreated the disease results in significant pain, eventual loss of the dentition and potentially an increased risk of systemic diseases. Previous molecular based studies have identified the bacterial species associated with periodontal disease in dogs; however without cultured strains from many of these species it has not been possible to study whether they play a role in the disease process. RESULTS: Using a quantitative polymerase chain reaction (qPCR) directed approach a range of microbiological media were screened and optimized to enrich for previously uncultivated target species. A systematic screening methodology was then employed to isolate the species of interest. In cases where the target species were not cultivable in isolation, helper strains grown underneath a nitrocellulose membrane were used to provide the necessary growth factors. This guided media optimization approach enabled the purification of 14 species, 8 of which we had previously been unable to cultivate in isolation. It is also applicable to the targeted isolation of isolates from species that have previously been cultured (for example to study intra-species variation) as demonstrated by the successful isolation of 6 targeted isolates of already cultured species. CONCLUSIONS: To our knowledge this is the first time this combination of qPCR guided media optimization, strategic screening and helper strain support has been used successfully to isolate previously uncultured bacteria. This approach can be applied to any uncultured bacterial species where knowledge of their nutritional requirements or low relative abundance impedes their isolation.


Subject(s)
Bacteria/classification , Bacteria/isolation & purification , Dental Plaque/veterinary , Dog Diseases/microbiology , Periodontal Diseases/veterinary , Animals , Bacteria/growth & development , Bacteriological Techniques/methods , Culture Media/chemistry , Dental Plaque/microbiology , Dogs , Periodontal Diseases/microbiology , Real-Time Polymerase Chain Reaction
12.
Article in English | MEDLINE | ID: mdl-24110386

ABSTRACT

In this paper we present a new type of head-mounted wireless neural recording device in a highly compact package, dedicated for untethered laboratory animal research and designed for future mobile human clinical use. The device, which takes its input from an array of intracortical microelectrode arrays (MEA) has ninety-seven broadband parallel neural recording channels and was integrated on to two custom designed printed circuit boards. These house several low power, custom integrated circuits, including a preamplifier ASIC, a controller ASIC, plus two SAR ADCs, a 3-axis accelerometer, a 48MHz clock source, and a Manchester encoder. Another ultralow power RF chip supports an OOK transmitter with the center frequency tunable from 3GHz to 4GHz, mounted on a separate low loss dielectric board together with a 3V LDO, with output fed to a UWB chip antenna. The IC boards were interconnected and packaged in a polyether ether ketone (PEEK) enclosure which is compatible with both animal and human use (e.g. sterilizable). The entire system consumes 17mA from a 1.2Ahr 3.6V Li-SOCl2 1/2AA battery, which operates the device for more than 2 days. The overall system includes a custom RF receiver electronics which are designed to directly interface with any number of commercial (or custom) neural signal processors for multi-channel broadband neural recording. Bench-top measurements and in vivo testing of the device in rhesus macaques are presented to demonstrate the performance of the wireless neural interface.


Subject(s)
Brain/physiology , Wireless Technology/instrumentation , Action Potentials/physiology , Amplifiers, Electronic , Animal Experimentation , Animals , Animals, Laboratory , Electrodes, Implanted , Head , Humans , Macaca/physiology
13.
Article in English | MEDLINE | ID: mdl-23365999

ABSTRACT

We present polymeric packaging methods used for subcutaneous, fully implantable, broadband, and wireless neurosensors. A new tool for accelerated testing and characterization of biocompatible polymeric packaging materials and processes is described along with specialized test units to simulate our fully implantable neurosensor components, materials and fabrication processes. A brief description of the implantable systems is presented along with their current encapsulation methods based on polydimethylsiloxane (PDMS). Results from in-vivo testing of multiple implanted neurosensors in swine and non-human primates are presented. Finally, a novel augmenting polymer thin film material to complement the currently employed PDMS is introduced. This thin layer coating material is based on the Plasma Enhanced Chemical Vapor Deposition (PECVD) process of Hexamethyldisiloxane (HMDSO) and Oxygen (O(2)).


Subject(s)
Neural Prostheses , Wireless Technology/instrumentation , Animals , Biocompatible Materials , Coated Materials, Biocompatible , Electrophysiological Phenomena , Humans , Macaca mulatta , Materials Testing , Prosthesis Design , Remote Sensing Technology/instrumentation , Siloxanes , Sus scrofa , Telemetry/instrumentation
14.
Article in English | MEDLINE | ID: mdl-22254977

ABSTRACT

A new model has been established in the domestic pig for neural prosthetic device development and testing. To this end, we report on a complete neural prosthetic developmental system using a wireless sensor as the implant, a pig as the animal model, and a novel data acquisition paradigm for actuator control. A new type of stereotactic frame with clinically-inspired fixations pins that place the pig brain in standard surgical plane was developed and tested with success during the implantation of the microsystem. The microsystem implanted was an ultra-low power (12.5 mW) 16-channel intracortical/epicranial device transmitting broadband (40 kS/s) data over a wireless infrared telemetric link. Pigs were implanted and neural data was collected over a period of 5 weeks, clearly showing single unit spiking activity.


Subject(s)
Prostheses and Implants , Animals , Swine
15.
Toxicol Sci ; 114(2): 183-92, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20044590

ABSTRACT

Chronic treatment with suprapharmacologic doses of peroxisome proliferator-activated receptor (PPAR) agonists has a known potential for causing left ventricular hypertrophy (LVH). The mechanism by which LVH develops is not well understood nor are biomarkers of it well characterized. Natriuretic peptides are important regulators of cardiac growth, blood volume, and arterial pressure and may be useful biomarkers of LVH and hemodynamic changes that precede it. We measured amino-terminal pro-atrial natriuretic peptide (NTproANP), amino-terminal pro-brain natriuretic peptide (NTproBNP), and cardiac troponin I (cTnI) concentrations in serum and plasma, as well as transcripts in left ventricular heart tissue for atrial natriuretic peptide precursor (Nppa), brain natriuretic peptide precursor (Nppb), and myosin heavy chain-beta (Myh7) as potential biomarkers of LVH induced by a PPARalpha/gamma dual agonist in Sprague-Dawley rats. We used magnetic resonance imaging, echocardiography, and hemodynamics to identify structural and functional cardiovascular changes related to the biomarkers. Heart-to-brain weight ratios (HW:BrW) were correlated with NTproANP, NTproBNP, and cTnI concentrations in serum as well as fold change in expression of Nppa and Nppb. LVH was characterized by increased left ventricular wall thickness and inner diameter, increased cardiac output, decreased arterial blood pressure, and increased heart rate. In these studies, each end point contributed to the early detection of LVH, the ability to monitor its progression, and demonstrated the ability of NTproANP concentration in serum to predict LVH and hemodynamic changes.


Subject(s)
Cardiovascular Agents/toxicity , Hypertrophy, Left Ventricular/diagnosis , PPAR alpha/agonists , PPAR gamma/agonists , Phenylpropionates/toxicity , Thiophenes/toxicity , Animals , Atrial Natriuretic Factor/genetics , Atrial Natriuretic Factor/metabolism , Biomarkers/metabolism , Disease Models, Animal , Echocardiography , Female , Heart/drug effects , Hypertrophy, Left Ventricular/chemically induced , Hypertrophy, Left Ventricular/genetics , Hypertrophy, Left Ventricular/metabolism , Magnetic Resonance Imaging , Male , Myocardium/metabolism , Myocardium/pathology , Natriuretic Peptide, Brain/genetics , Natriuretic Peptide, Brain/metabolism , Organ Size/drug effects , PPAR alpha/metabolism , PPAR gamma/metabolism , Peptide Fragments/genetics , Peptide Fragments/metabolism , Rats , Rats, Sprague-Dawley , Signal Transduction , Troponin T/genetics , Troponin T/metabolism
16.
Proc IEEE Inst Electr Electron Eng ; 98(3): 375-388, 2010.
Article in English | MEDLINE | ID: mdl-21654935

ABSTRACT

Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature's amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic "brain-interfaces" within the body, a point of special emphasis of this paper.

17.
Article in English | MEDLINE | ID: mdl-19964128

ABSTRACT

A multitude of neuroengineering challenges exist today in creating practical, chronic multichannel neural recording systems for primate research and human clinical application. Specifically, a) the persistent wired connections limit patient mobility from the recording system, b) the transfer of high bandwidth signals to external (even distant) electronics normally forces premature data reduction, and c) the chronic susceptibility to infection due to the percutaneous nature of the implants all severely hinder the success of neural prosthetic systems. Here we detail one approach to overcome these limitations: an entirely implantable, wirelessly communicating, integrated neural recording microsystem, dubbed the Brain Implantable Chip (BIC).


Subject(s)
Amplifiers, Electronic , Analog-Digital Conversion , Electrodes, Implanted , Electroencephalography/instrumentation , Evoked Potentials, Motor/physiology , Motor Cortex/physiology , Signal Processing, Computer-Assisted/instrumentation , Animals , Equipment Design , Equipment Failure Analysis , Humans , Miniaturization , Primates , Rats , Reproducibility of Results , Sensitivity and Specificity
18.
J Am Soc Nephrol ; 20(2): 267-77, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19092124

ABSTRACT

Administration of activated protein C (APC) protects from renal dysfunction, but the underlying mechanism is unknown. APC exerts both antithrombotic and cytoprotective properties, the latter via modulation of protease-activated receptor-1 (PAR-1) signaling. We generated APC variants to study the relative importance of the two functions of APC in a model of LPS-induced renal microvascular dysfunction. Compared with wild-type APC, the K193E variant exhibited impaired anticoagulant activity but retained the ability to mediate PAR-1-dependent signaling. In contrast, the L8W variant retained anticoagulant activity but lost its ability to modulate PAR-1. By administering wild-type APC or these mutants in a rat model of LPS-induced injury, we found that the PAR-1 agonism, but not the anticoagulant function of APC, reversed LPS-induced systemic hypotension. In contrast, both functions of APC played a role in reversing LPS-induced decreases in renal blood flow and volume, although the effects on PAR-1-dependent signaling were more potent. Regarding potential mechanisms for these findings, APC-mediated PAR-1 agonism suppressed LPS-induced increases in the vasoactive peptide adrenomedullin and infiltration of iNOS-positive leukocytes into renal tissue. However, the anticoagulant function of APC was responsible for suppressing LPS-induced stimulation of the proinflammatory mediators ACE-1, IL-6, and IL-18, perhaps accounting for its ability to modulate renal hemodynamics. Both variants reduced active caspase-3 and abrogated LPS-induced renal dysfunction and pathology. We conclude that although PAR-1 agonism is solely responsible for APC-mediated improvement in systemic hemodynamics, both functions of APC play distinct roles in attenuating the response to injury in the kidney.


Subject(s)
Kidney Diseases/metabolism , Kidney/injuries , Protein C/physiology , Animals , Humans , Inflammation , Interleukin-18/metabolism , Interleukin-6/metabolism , Kidney/metabolism , Lipopolysaccharides/metabolism , Male , Microcirculation , Protein C/metabolism , Rats , Rats, Sprague-Dawley , Receptor, PAR-1/metabolism , Signal Transduction
19.
Article in English | MEDLINE | ID: mdl-18001985

ABSTRACT

A prototype cortical neural interface microsystem has been developed for brain implantable neuroengineering applications, featuring hybrid RF (radio-frequency) inductive and IR (infrared) optical telemetries. The system is aimed at neural recording from primates by converting cortical signals to a digital stream of IR light pulses, while acquiring clock signal and electrical power through RF induction. The implantable unit employs a flexible LCP (liquid crystal polymer) substrate for integration of analog, digital, and optoelectronic components, while adapting to the anatomical and physiological constraints of the environment. An ultra-low power analog CMOS chip, which includes preamplifier and multiplexing circuitry, is directly flip-chip bonded to the microelectrode array to form the immediate cortical neuroprobe device. A 16-channel version of the probe has been tested in various in-vivo animal experiments, including measurements of neural activity in somatosensory cortex of a rat.


Subject(s)
Cerebral Cortex , Infrared Rays , Prostheses and Implants , Radio Waves , Signal Transduction , Telemetry/instrumentation , Animals , Humans , Liquid Crystals , Polymers , Rats , Telemetry/methods
20.
J Neural Eng ; 4(3): 213-8, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17873423

ABSTRACT

Recent advances in functional electrical stimulation (FES) show significant promise for restoring voluntary movement in patients with paralysis or other severe motor impairments. Current approaches for implantable FES systems involve multisite stimulation, posing research issues related to their physical size, power and signal delivery, surgical and safety challenges. To explore a different means for delivering the stimulus to a distant muscle nerve site, we have elicited in vitro FES response using a high efficiency microcrystal photovoltaic device as a neurostimulator, integrated with a biocompatible glass optical fiber which forms a lossless, interference-free lightwave conduit for signal and energy transport. As a proof of concept demonstration, a sciatic nerve of a frog is stimulated by the microcrystal device connected to a multimode optical fiber (core diameter of 62.5 microm), which converts optical activation pulses ( approximately 100 micros) from an infrared semiconductor laser source (at 852 nm wavelength) into an FES signal.


Subject(s)
Action Potentials/physiology , Electric Stimulation/instrumentation , Fiber Optic Technology/instrumentation , Lasers , Prostheses and Implants , Sciatic Nerve/physiology , Animals , Electric Stimulation/methods , Equipment Design , Equipment Failure Analysis , Miniaturization , Optical Fibers , Rana catesbeiana
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