A Novel Model to Generate Heterogeneous and Realistic Time-Series Data for Post-Stroke Rehabilitation Assessment.

The application of machine learning-based tele-rehabilitation faces the challenge of limited availability of data. To overcome this challenge, data augmentation techniques are commonly employed to generate synthetic data that reflect the configurations of real data. One such promising data augmentation technique is the Generative Adversarial Network (GAN). However, GANs have been found to suffer from mode collapse, a common issue where the generated data fails to capture all the relevant information from the original dataset. In this paper, we aim to address the problem of mode collapse in GAN-based data augmentation techniques for post-stroke assessment. We applied the GAN to generate synthetic data for two post-stroke rehabilitation datasets and observed that the original GAN suffered from mode collapse, as expected. To address this issue, we propose a Time Series Siamese GAN (TS-SGAN) that incorporates a Siamese network and an additional discriminator. Our analysis, using the longest common sub-sequence (LCSS), demonstrates that TS-SGAN generates data uniformly for all elements of two testing datasets, in contrast to the original GAN. To further evaluate the effectiveness of TS-SGAN, we encode the generated dataset into images using Gramian Angular Field and classify them using ResNet-18. Our results show that TS-SGAN achieves a significant accuracy increase of classification accuracy (35.2%-42.07%) for both selected datasets. This represents a substantial improvement over the original GAN.

The professional development and career journey into musculoskeletal first contact physiotherapy: a telephone interview study.

(A)BACKGROUND: Musculoskeletal (MSK) first contact physiotherapy (FCP) is being rolled out in the National Health Service, but limited research exists on career pathways into MSK FCP, or on pre-and-post-registration educational preparation for the knowledge and skills that are required for musculoskeletal first contact physiotherapy. (B) OBJECTIVES: From the perspectives of existing MSK FCPs, the study sought to understand the pre-and-post-registration professional developmental journey into musculoskeletal first contact physiotherapy. (C) METHODS: Semi-structured interviews over the telephone were conducted with a self-selected and snowball sample of 15 MSK FCPs from across Britain. Framework analysis was used to analyze the interview transcripts. (D) RESULTS: Four overarching themes were identified: (1) Decision to choose a career path as a MSK FCP; (2) Relevancy of pre-registration physiotherapy (PT) education for MSK FCP; (3) Relevancy of post-registration continuing professional development for MSK FCP, and; (4) Improving pre-registration PT education for the foundational knowledge and skills required to work in musculoskeletal first contact physiotherapy. Each overarching theme generated several subthemes. (E)CONCLUSION: The research contributes to understanding the career pathway into the MSK FCP role and showed what relevant knowledge and skills were acquired for this role at pre-and-post registration levels. Findings will inform guidance for pre-registration PT curriculum development.

A comprehensive evaluation of state-of-the-art time-series deep learning models for activity-recognition in post-stroke rehabilitation assessment.

The recent COVID-19 pandemic has further high-lighted the need for improving tele-rehabilitation systems. One of the common methods is to use wearable sensors for monitoring patients and intelligent algorithms for accurate and objective assessments. An important part of this work is to develop an efficient evaluation algorithm that provides a high-precision activity recognition rate. In this paper, we have investigated sixteen state-of-the-art time-series deep learning algorithms with four different architectures: eight convolutional neural networks configurations, six recurrent neural networks, a combination of the two and finally a wavelet-based neural network. Additionally, data from different sensors' combinations and placements as well as different pre-processing algorithms were explored to determine the optimal configuration for achieving the best performance. Our results show that the XceptionTime CNN architecture is the best performing algorithm with normalised data. Moreover, we found out that sensor placement is the most important attribute to improve the accuracy of the system, applying the algorithm on data from sensors placed on the waist achieved a maximum of 42% accuracy while the sensors placed on the hand achieved 84%. Consequently, compared to current results on the same dataset for different classification categories, this approach improved the existing state of the art accuracy from 79% to 84%, and from 80% to 90% respectively.

The mechanical energetics of walking across the adult lifespan.

PURPOSE: Understanding what constitutes normal walking mechanics across the adult lifespan is crucial to the identification and intervention of early decline in walking function. Existing research has assumed a simple linear alteration in peak joint powers between young and older adults. The aim of the present study was to quantify the potential (non)linear relationship between age and the joint power waveforms of the lower limb during walking. METHODS: This was a pooled secondary analysis of the authors' (MT, KD, JJ) and three publicly available datasets, resulting in a dataset of 278 adults between the ages of 19 to 86 years old. Three-dimensional motion capture with synchronised force plate assessment was performed during self-paced walking. Inverse dynamics were used to quantity joint power of the ankle, knee, and hip, which were time-normalized to 100 stride cycle points. Generalized Additive Models for location, scale and shape (GAMLSS) was used to model the effect of cycle points, age, walking speed, stride length, height, and their interaction on the outcome of each joint's power. RESULTS: At both 1m/s and 1.5 m/s, A2 peaked at the age of 60 years old with a value of 3.09 (95% confidence interval [CI] 2.95 to 3.23) W/kg and 3.05 (95%CI 2.94 to 3.16), respectively. For H1, joint power peaked with a value of 0.40 (95%CI 0.31 to 0.49) W/kg at 1m/s, and with a value of 0.78 (95%CI 0.72 to 0.84) W/kg at 1.5m/s, at the age of 20 years old. For H3, joint power peaked with a value of 0.69 (95%CI 0.62 to 0.76) W/kg at 1m/s, and with a value of 1.38 (95%CI 1.32 to 1.44) W/kg at 1.5m/s, at the age of 70 years old. CONCLUSIONS: Findings from this study do not support a simple linear relationship between joint power and ageing. A more in-depth understanding of walking mechanics across the lifespan may provide more opportunities to develop early clinical diagnostic and therapeutic strategies for impaired walking function. We anticipate that the present methodology of pooling data across multiple studies, is a novel and useful research method to understand motor development across the lifespan.

Role of the halo sign in the assessment of giant cell arteritis: a systematic review and meta-analysis.

OBJECTIVES: This systematic review and meta-analysis aimed to evaluate the diagnostic value of the halo sign in the assessment of GCA. METHODS: A systematic literature review was performed using MEDLINE, EMBASE and Cochrane central register databases up to August 2020. Studies informing on the sensitivity and specificity of the US halo sign for GCA (index test) were selected. Studies with a minimum of five participants were included. Study articles using clinical criteria, imaging such as PET-CT and/or temporal artery biopsy (TAB) as the reference standards were selected. Meta-analysis was conducted with a bivariate model. RESULTS: The initial search yielded 4023 studies. Twenty-three studies (patients n = 2711) met the inclusion criteria. Prospective (11 studies) and retrospective (12 studies) studies in academic and non-academic centres were included. Using clinical diagnosis as the standard (18 studies) yielded a pooled sensitivity of 67% (95% CI: 51, 80) and a specificity of 95% (95% CI: 89, 98%). This gave a positive and negative likelihood ratio for the diagnosis of GCA of 14.2 (95% CI: 5.7, 35.5) and 0.375 (95% CI: 0.22, 0.54), respectively. Using TAB as the standard (15 studies) yielded a pooled sensitivity of 63% (95% CI: 50, 75) and a specificity of 90% (95% CI: 81, 95). CONCLUSION: The US halo sign is a sensitive and specific approach for GCA assessment and plays a pivotal role in diagnosis of GCA in routine clinical practice. REGISTRATION: PROSPERO 2020 CRD42020202179.

Halo score (temporal artery, its branches and axillary artery) as a diagnostic, prognostic and disease monitoring tool for Giant Cell Arteritis (GCA).

BACKGROUND: Giant cell arteritis (GCA) is a common large vessel vasculitis of the elderly, often associated with sight loss. Glucocorticoids (GC remain the mainstay of treatment, although biologic treatments have been approved. Biomarkers predicting disease severity, relapse rates and damage are lacking in GCA.EULAR recommends ultrasound (US) as the first investigation for suspected GCA. The cardinal US finding, a non-compressible halo, is currently categorised as either negative or positive. However, the extent and severity of this finding may vary.In this study, we hypothesise whether the extent and severity of the halo sign [calculated as a single composite Halo score (HS)] of temporal and axillary arteries may be of diagnostic, prognostic and monitoring importance; whether baseline HS is linked to disease outcomes, relapses and damage; whether HS can stratify GCA patients for individual treatment needs; whether HS can function as an objective monitoring tool during follow up. METHODS: This is a prospective, observational study. Suspected GCA Participants will be selected from the GCA FTC at the participating centres in the UK. Informed consent will be obtained, and patients managed as part of standard care. Patients with GCA will have HS (temporal and axillary arteries) measured at baseline and months 1,3,6 and 12 long with routine clinical assessments, blood sampling and patient-reported outcomes (EQ5D). Non-GCA patients will be discharged back to the referral team and will have a telephone interview in 6 months.We aim to recruit 272 suspected GCA referrals which should yield 68 patients (25% of referrals) with confirmed GCA. The recruitment will be completed in 1 year with an estimated total study period of 24 months. DISCUSSION: The identification of prognostic factors in GCA is both timely and needed. A prognostic marker, such as the HS, could help to stratify GCA patients for an appropriate treatment regimen. Tocilizumab, an IL-6R blocking agent, switches off the acute phase response (C-Reactive Protein), making it difficult to measure the disease activity. Therefore, an independent HS, and changes in that score during treatment and follow-up, maybe a more objective measure of response compare to patient-reported symptoms and clinical assessment alone.

Challenges and Learning Opportunities of Pre-Registration Physiotherapy Placements in First Contact Settings: The Perspectives of Musculoskeletal First Contact Physiotherapists.

OBJECTIVES: As musculoskeletal first contact physiotherapy is rolled out into primary healthcare in Britain, this could offer up new practice-based educational opportunities for pre-registration physiotherapy students. Thus, the present study sought to explore the perceived challenges and learning opportunities of pre-registration physiotherapy placements in musculoskeletal first contact physiotherapy settings from first contact physiotherapists' perspectives. METHODS: Using a qualitative strategy, 15 musculoskeletal first contact physiotherapists from different geographical locations in Britain, participated in telephone mediated semi-structured interviews. Participants were self-selected through a Chartered Society of Physiotherapy fortnightly bulletin and online forum for first contact physiotherapists, or recruited via snowball sampling. Interview transcripts were analysed according to framework analysis - and the findings were member-checked by proxy. RESULTS: Three core themes emerged: operational challenges, challenges for pre-registration physiotherapy students and learning opportunities for pre-registration physiotherapy students. Operational challenges included: ensuring sufficient support from first contact physiotherapy practice educators; financial cost implications of placements, and; lack of capacity within the existing first contact physiotherapy workforce to provide placements. Challenges for physiotherapy students involved: time pressures and stressors of a first contact physiotherapy placement; identifying red flags, and; complexity of patient presentations. Identified learning opportunities for physiotherapy students were: experience of a specialised physiotherapy role in a primary healthcare setting; bringing awareness of first contact physiotherapy as a potential career pathway, and; experience multidisciplinary team working in primary care. CONCLUSIONS: By seeking the perspectives of first contact physiotherapists, this study provides the first step for the development of placements in an emerging practice area.

The association of working alliance, outcome expectation, adherence and self-efficacy with clinical outcomes for Achilles tendinopathy: A feasibility cohort study (the MAP study).

INTRODUCTION: This study evaluated the feasibility of a large longitudinal cohort study utilizing an online platform to investigate the association and predictive relationship of working alliance, outcome expectations, adherence and self-efficacy with outcome in Achilles tendinopathy. The objectives were: (1) to determine the recruitment and retention rate and (2) to carry out preliminary data analysis of the selected variables and clinical outcomes. METHODS: A multi-centred, longitudinal feasibility cohort study was used. Eligible participants were directed to a bespoke online platform hosting study information and the outcome measures in the form of an online questionnaire. Responses from the online questionnaire were collected on three occasions: at baseline, at 6 and at 12 weeks following completion of the first questionnaire. Feasibility outcomes (recruitment and retention rates) were described using descriptive statistics. RESULTS: The website recorded a total 55 views. These 55 views resulted in 24 participants consenting to join the study. The questionnaire at baseline was started 63 times and completed on 60 separate occasions resulting in a 95% conversion rate. Retainment for completion of the questionnaire for a second time was 83.3% and for the third time was 66.6%. All questionnaires were completed fully yielding a missing data indicator of 0%. CONCLUSIONS: Feasibility studies ask the question 'can this be done'? Based on the data from recruitment and rates and exploratory correlation analysis a future study can be done; this previously untested online platform appears feasible, but changes could be useful before proceeding to a much larger study.

Musculoskeletal ultrasound imaging - An exploration of physiotherapists' interests and use in practice.

BACKGROUND: Musculoskeletal ultrasound imaging (MSKUSI) has gained popularity; several professions have expressed an interest in this application but the clinical use by physiotherapists has not been fully researched. OBJECTIVES: To explore physiotherapists' interests and use of MSKUSI in practice. DESIGN: Sequential mixed-methods; questionnaire followed by semi-structured interviews. METHOD: A questionnaire was developed and distributed to gain initial information, (75 responses). Analysis informed topic-guide development and enabled a purposive-sampling strategy for semi-structured interviews that explored physiotherapists' interests, education and clinical use of MSKUSI (n = 11). Interview data were analysed thematically. RESULTS: Five themes were identified: 1. Professional skill set - physiotherapists' suitability for MSKUSI. 2. Factors that have impacted physiotherapists' ability to use MSKUSI. 3. Physiotherapists' motivation to use ultrasound - improving patient focused care. 4. Quality assurance strategies. 5. Application of biopsychosocial model. Themes revealed links between physiotherapists' core skills, knowledge and professional experiences that align with MSKUSI requirements. Some participants reported support accessing education but many described challenges finding appropriate mentorship. Participants observed education did not always reflect practice typical of physiotherapists. Application of clinical reasoning processes utilised by physiotherapists was regarded as integral to patient-focused scanning. CONCLUSIONS: Physiotherapists' professional training and musculoskeletal practice are seen as a foundation for education in MSKUSI. Accessing education can be challenging, in particular mentorship that fully incorporates the biopsychosocial model. Proposed roles for MSKUSI for physiotherapists include verification of clinical assessment findings for diagnosis and facilitation of patient education. The potential to streamline patient pathways and optimise resource management warrants investigation.

Musculoskeletal ultrasound imaging - Integration with the biopsychosocial model.

BACKGROUND AND METHOD: Musculoskeletal ultrasound imaging, (MSKUSI) has become a popular imaging modality in recent years and is being utilised by a variety of professions in clinical environments beyond radiology departments. A previously published study exploring physiotherapists' interests and use of MSKUSI in practice included in-depth interviews of participants, (n = 11). The data from this qualitative study were analysed thematically and five themes were identified; one was 'Application of the biopsychosocial model', the basis of this paper. RESULT: The theme, 'Application of the biopsychosocial model' drew together three categories of analysed data: clinical reasoning, professional variance and communication opportunity. 'Clinical reasoning' reflected the participants' value on subjective assessment information and the integration of ultrasound imaging with physical examination findings. 'Professional variance' observed the scanning processes undertaken by physiotherapists tended to vary from other professionals, the physiotherapists perceived their use of dynamic imaging was greater, in particular scanning in symptom provoking positions. Another variance observed was the style of communication that physiotherapists used when scanning, this was categorised as a 'communication opportunity' as it represented an event that could be utilised to promote patient understanding of their presentation, link imaging findings to proposed management and enhance compliance with rehabilitation strategies. Participants emphasised their responsibility when communicating with patients to avoid language that could promote unhelpful behaviour, e.g. catastrophisation. CONCLUSION: Participants placed value on integrating musculoskeletal ultrasound imaging into the biopsychosocial model, further research to explore the impact of this approach on patients' clinical outcomes and reported experiences is required.

Managing Achilles Pain (the MAP study) - A process evaluation of data collection methods.

BACKGROUND: Process evaluations explore the way in which a study was conducted. The Managing Achilles Pain study (MAP study) had the primary aim of assessing the feasibility of the protocol for a future large longitudinal cohort study that would investigate the association and predictive relationship of self-efficacy, working alliance and expectations with outcome in the management of Achilles tendinopathy. OBJECTIVES: This study aimed to evaluate the processes conducted in the MAP study by exploring the acceptability of the study procedures from the participants' and physiotherapists' perspectives. DESIGN: A qualitative evaluation using semi-structured telephone interviews. METHOD: All physiotherapists and participants who participated in the MAP study were invited. Data from physiotherapists (n = 6) and participants (n = 7) were transcribed and analysed using the Framework Approach. FINDINGS: From the physiotherapists' perspective 4 themes were identified relating to obstacles; (1) access to participants; (2) recall; (3) visibility; (4) time, and 4 themes were identified relating to facilitating success; (1) training; (2) motivation; (3) incentives; (4) simplicity. From the participants' perspective 2 themes were identified relating to obstacles; (1) information from the physiotherapist; (2) follow up, 3 themes were identified relating to facilitating success; (1) motivation; (2) website; (3) questionnaire, and 1 theme relating to unintended consequences of participating in the study; positive experience. CONCLUSIONS: Although clinicians are enthused to be involved in research, organisational factors impact levels of engagement. Key influences to optimising the potential success of a study include the publicising of the study; optimising verbal recruitment strategies; and clarity in communication.

The concept of margins of stability can be used to better understand a change in obstacle crossing strategy with an increase in age.

The purpose of the current study was to use the margins of stability (MoS) to investigate how older adults choose between minimizing the risk of a forward fall when crossing an obstacle and the ease of maintaining forward progression during the steps taken behind the obstacle. In the current study 143 community-dwelling older adults aged between 55 and 83 years old, were divided into three age groups based on tertials of age. All participants were asked to complete five trials of obstacle walking and five trials of normal walking. For the trials of normal walking, the main difference between groups was that MoS at initial contact was lower in the older age groups. For the trials of obstacle crossing the MoS at the instants of obstacle crossing with both the leading and trailing limb became smaller with an increase in age. This result might imply that older people choose to use a strategy during obstacle crossing that results in smaller chance of falling forward if an obstacle was struck. A negative consequence of this more conservative strategy was a smaller MoS at the instants of initial contact after crossing the obstacle, thus a larger chance of a backward fall. These findings provide more insight into the regulation of stability during obstacle crossing and specifically in the differences in strategy between younger and older people, and therefore these results might be used for further research to investigate whether obstacle crossing strategies are trainable in older adults, which could be used as advisory programs aimed at fall prevention and/or engagement in an active lifestyle.

Are there associations with age and sex in walking stability in healthy older adults?

The variability of the centre of pressure (COP) during walking can provide information in relation to stability when walking. The aim of this study was to investigate if age and sex were associated with COP variability, COP excursions, and COP velocities during walking. One-hundred and fourteen older adults (age 65.1±5.5 yrs.) participated in the study. A Kistler force platform (1000Hz) recorded the ground reaction forces and COPs during walking at a self-selected walking speed. The stance phase was divided, using the vertical GRF, into four sub-phases: loading response (LR), mid-stance (MSt), terminal stance (TSt), and pre-swing (PSw). The standard deviations of the COP displacement (variability), the COP velocity, and COP excursion in the medial-lateral and anterior-posterior directions, as well as the resultant magnitude were assessed. When controlling for walking speed, a greater age was associated with a higher variability and excursion of the COP during LR only suggesting that stability is maintained during the majority of the stance phase. During LR lower COP velocity was significantly associated for females for anterior-posterior and total COP, which may be a strategy to facilitate stability before, and moving into, MSt and TSt.

Exploring assistant practitioners' views of their role and training.

AIM: To examine the views of assistant practitioners and trainee assistant practitioners regarding experiences of practice in relation to the autonomy of the role and level of supervision, the training involved and support experienced in undertaking the foundation degree, and the effects of the assistant practitioner role in the workplace. METHOD: A service evaluation was undertaken in which a small cross-sectional quantitative survey was distributed to trainee assistant practitioners undertaking the foundation degree, and assistant practitioners who had previously completed the foundation degree or who had qualified via another route. RESULTS: A total of 93 questionnaires were returned. The data indicate that there is some uncertainty surrounding the skills and competence of those undertaking the foundation degree, and a lack of opportunity for career progression for unregistered staff. CONCLUSION: Increased understanding of the scope and role of assistant practitioners and the academic requirements of the foundation degree is required to increase assistant practitioner numbers.

Introduction of a new ward round approach in a cardiothoracic critical care unit.

BACKGROUND: Francis (2013) described inconsistent ward rounds and failures to conduct ward rounds properly as contributing factors to the poor care seen at the Mid Staffordshire Foundation Trust. He suggested that the absence of a nurse at the bedside had clear consequences for communication, ward round efficiency and patient safety. He recommended that nurses should be actively involved in ward rounds and linked this to high quality patient care. AIM: To share an experience of introducing a ward round checklist, a bedside nurse verbal summary and the development of standard operating procedure for Ward Rounds in cardiothoracic critical care unit to improve patient safety and care. DESIGN AND METHODS: Semi structured interviews of six registered nurses. A questionnaire to 69 registered nurses. An electronic questionnaire sent to 23 members of the MDT. An observational audit of seven ward rounds reviewing 69 patients. RESULTS: 97% of nurses agreed that verbal summarizing had improved clarity and 90% felt that it had improved patient care. 87% of the MDT respondents stated that they had noticed an improvement in the attendance of the bedside nurse at the ward round review. The ward round checklist reduced omissions. Communication with patients during ward rounds was an area which needed to be improved. CONCLUSIONS: The introduction of a new ward round approach and audit of its practice has enabled an improvement in the quality of patient care by: Giving more opportunity for the nurse to participate and feel part of the ward round. Reduction of omissions through the use of a ward round checklist. Improved clarity among the MDT by the use of bedside nurse verbal summarizing of the plan of care. RELEVANCE TO CLINICAL PRACTICE: Nurses' full participation in ward rounds is essential to ensure effective communication and enhance patient safety.

Differential antiviral effect of PEG-interferon-alpha-2b on HIV and HCV in the treatment of HIV/HCV co-infected patients.

OBJECTIVE: The major antiviral effect of interferon (IFN)-alpha on hepatitis C virus (HCV) is blocking of virion production from infected cells. We now investigate the previously unknown mechanism of action of IFN-alpha against HIV. METHODS: HIV kinetics in parallel to HCV kinetics and IFN pharmacokinetics during pegylated-IFN-alpha-2b (1.5 microg/Kg q.w., PEG-IFN) and ribavirin (1-1.2 g daily) treatment in nine HIV patients co-infected with HCV genotype 1 were analyzed. In vivo modeling predictions of suppression of HIV replication by PEG-IFN in CD8-depleted peripheral blood mononuclear cells were verified by in vitro experiments. RESULTS: HCV and HIV show different viral decline patterns after administration of PEG-IFN. Unlike the bi-phasic decline shown by HCV, HIV shows a slow continuous decline during the first week, with no rebound when PEG-IFN levels decline. Fitting of HIV kinetics with known half-lives of free virus and infected cells indicates that the major effect of IFN on HIV is to block de novo infection rather than to block virion production. The magnitude of the antiviral effect is similar (mean 1.1 log10 decline at 7 days) to those of direct anti-HIV drugs, but shows an inverse correlation with baseline viremia. In vitro studies show that preincubation with IFN renders a suppression of HIV replication superior to that of treatment postinfection, thus corroborating the mathematical analysis in vivo. CONCLUSION: The complimentary antiviral properties of IFN-alpha and antiretroviral therapy suggest a role for pharmacokinetically improved formulations of IFN as part of salvage therapy for HIV-infected individuals.

Clinical inquiries. What is the recommended evaluation and treatment for elevated serum prolactin?

History and physical examination can distinguish among most physiologic, pharmacologic, or pathologic causes of an elevated serum prolactin level (SPL) (strength of recommendation [SOR]: C, expert opinion). Patients with unexplained elevations of serum prolactin or with a level above 200 ng/mL should undergo imaging of the sella turcica (SOR: C, expert opinion). Mildly elevated SPL due to physiologic causes may be managed expectantly (SOR: B, cohort studies) and pharmacologic elevations may be treated by discontinuing the causative medication (SOR: C, expert opinion). Elevated SPL due to pathologic causes requires both monitoring for complications and treatment of the underlying condition (SOR: C, expert opinion). Dopamine agonists are effective for patients requiring drug treatment (SOR: B, systematic review of cohort studies), and cabergoline is more effective and better tolerated than bromocriptine (SOR: B, randomized controlled trial [RCT]). Surgery is reserved for symptomatic patients not controlled medically (SOR: C, expert opinion).

Dynamic monitoring of cytotoxicity on microelectronic sensors.

A real-time cell electronic sensing (RT-CES) system was used for label-free, dynamic measurement of cell responses to cytotoxicants. Cells were grown onto the surfaces of microelectronic sensors, which are comprised of circle-on-line electrode arrays and are integrated into the bottom surfaces of the microtiter plate. Changes in cell status such as cell number, viability, morphology, and adherence were monitored and quantified by detecting sensor electrical impedance. For cell quantification and viability measurement, the data generated on the RT-CES system correlated well with those from the colorimetric (MTT) assay. For cytotoxicity assessment, cells growing on microelectronic sensors were treated with different cytotoxicants, such as arsenic, mercury, and sodium dichromate. The dynamic responses of the cells to the toxicants were continuously monitored by the RT-CES system. On the basis of the IC50 values, the RT-CES system displays an equal sensitivity to the neutral red uptake assay at specific time points. Furthermore, because the RT-CES system provides real-time information regarding the state of cell morphology and adhesion in addition to cell number, we were able to discern a previously unreported effect of arsenic on NIH 3T3 cells prior to cell death. Also, using the RT-CES system, we were able to monitor cytotoxicity effects that occur within a minute of compound addition. Taken together, the RT-CES system allows for real-time, continuous monitoring and quantitative recording of the whole assay process and provides new insight into the cell-toxicant interaction.

Label-free, real-time monitoring of IgE-mediated mast cell activation on microelectronic cell sensor arrays.

Immunoglobulin E (IgE)-mediated mast cell activation is involved in the immediate phase of allergic reactions and plays a central role in the onslaught and persistence of allergic diseases. IgE-mediated mast cell activation includes two important events: cell sensitization resulting from IgE binding to Fc (FcepsilonRI) receptor and cell activation triggered by allergen-mediated oligomerization of membrane-bound IgE. Real-time monitoring of these events is needed to dissect the molecular mechanisms underlying IgE-mediated mast cell activation. Existing technologies are limited to label-based end-point assay formats, which detect either early signaling or final phase of mast cell activation. We describe a microelectronic cell sensor-based technology allowing dynamic monitoring of IgE-mediated mast cell sensitization and activation in real-time without any labeling steps. RBL-2H3 mast cells were cultured onto the surface of microelectronic cell sensor arrays integrated into the bottom of microtiter plates, which record electric properties, such as impedance between cell membrane and sensor surface. In the presence of the allergen, dinitrophenyl (DNP)-bovine serum albumin (BSA), anti-DNP IgE-sensitized cells were activated within 5 min and the entire activation process was quantitatively and continuously recorded. Impedance measurements correlate with morphological dynamics and mediator release as measured by beta-hexosaminidase activity, and can be blocked by pharmacological agents, inhibiting IgE-mediated signaling. The assay on microelectronic cell sensor arrays can be scaled up for high-throughput screening of pharmacological inhibitors of IgE-mediated mast cell activation and other cell-based receptor-ligand assays.