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2.
Methods Mol Biol ; 2394: 343-376, 2022.
Article in English | MEDLINE | ID: mdl-35094337

ABSTRACT

We fabricated a novel single molecule nanosensor by integrating a solid-state nanopore and a double nanohole nanoaperture. The nanosensor employs Self-Induced Back-Action (SIBA) for optical trapping and enables SIBA-Actuated Nanopore Electrophoresis (SANE) for concurrent acquisition of bimodal optical and electrical signatures of molecular interactions. This work describes how to fabricate and use the SANE sensor to quantify antibody-ligand interactions. We describe how to analyze the bimodal optical-electrical data to improve upon the discrimination of antibody and ligand versus bound complex compared to electrical measurements alone. Example results for specific interaction detection are described for T-cell receptor-like antibodies (TCRmAbs) engineered to target peptide-presenting Major Histocompatibility Complex (pMHC) ligands, representing a model of target ligands presented on the surface of cancer cells. We also describe how to analyze the bimodal optical-electrical data to discriminate between specific and non-specific interactions between antibodies and ligands. Example results for non-specific interactions are shown for cancer-irrelevant TCRmAbs targeting the same pMHCs, as a control. These example results demonstrate the utility of the SANE sensor as a potential screening tool for ligand targets in cancer immunotherapy, though we believe that its potential uses are much broader.


Subject(s)
Nanopores , Neoplasms , Electrophoresis , Immunotherapy , Ligands , Nanotechnology/methods
3.
RSC Adv ; 11(39): 24398-24409, 2021.
Article in English | MEDLINE | ID: mdl-34354824

ABSTRACT

Nanopore probing of molecular level transport of proteins is strongly influenced by electrolyte type, concentration, and solution pH. As a result, electrolyte chemistry and applied voltage are critical for protein transport and impact, for example, capture rate (C R), transport mechanism (i.e., electrophoresis, electroosmosis or diffusion), and 3D conformation (e.g., chaotropic vs. kosmotropic effects). In this study, we explored these using 0.5-4 M LiCl and KCl electrolytes with holo-human serum transferrin (hSTf) protein as the model protein in both low (±50 mV) and high (±400 mV) electric field regimes. Unlike in KCl, where events were purely electrophoretic, the transport in LiCl transitioned from electrophoretic to electroosmotic with decreasing salt concentration while intermediate concentrations (i.e., 2 M and 2.5 M) were influenced by diffusion. Segregating diffusion-limited capture rate (R diff) into electrophoretic (R diff,EP) and electroosmotic (R diff,EO) components provided an approach to calculate the zeta-potential of hSTf (ζ hSTf) with the aid of C R and zeta potential of the nanopore surface (ζ pore) with (ζ pore-ζ hSTf) governing the transport mechanism. Scrutinization of the conventional excluded volume model revealed its shortcomings in capturing surface contributions and a new model was then developed to fit the translocation characteristics of proteins.

4.
Neurosci Lett ; 762: 136169, 2021 09 25.
Article in English | MEDLINE | ID: mdl-34390772

ABSTRACT

Children with hemiplegic cerebral palsy (HCP) often show disturbances of somatosensation. Despite extensive evidence of somatosensory deficits, neurophysiological alterations associated with somatosensory deficits in children with HCP have not been elucidated. Here, we aim to assess phase synchrony within and between contralateral primary (S1) and secondary (S2) somatosensory areas in children with HCP. Intra-regional and inter-regional phase synchronizations within and between S1 and S2 were estimated from somatosensory evoked fields (SEFs) in response to passive pneumatic stimulation of contralateral upper extremities and recorded with pediatric magnetoencephalography (MEG) in children with HCP and typically developing (TD) children. We found aberrant phase synchronizations within S1 and between S1 and S2 in both hemispheres in children with HCP. Specifically, the less-affected (LA) hemisphere demonstrated diminished phase synchronizations after the stimulus onset up to ~120 ms compared to the more-affected (MA) hemisphere and the dominant hemisphere of TD children, while the MA hemisphere showed enhanced phase synchronizations after ~100 ms compared to the LA hemisphere and the TD dominant hemisphere. Our findings indicate abnormal somatosensory functional connectivity in both hemispheres of children with HCP.


Subject(s)
Cerebral Palsy/physiopathology , Hemiplegia/physiopathology , Somatosensory Cortex/physiopathology , Cerebral Palsy/complications , Child , Evoked Potentials, Somatosensory/physiology , Female , Hemiplegia/etiology , Humans , Magnetoencephalography , Male
5.
Electrophoresis ; 42(7-8): 899-909, 2021 04.
Article in English | MEDLINE | ID: mdl-33340118

ABSTRACT

Recently, we developed a fabrication method-chemically-tuned controlled dielectric breakdown (CT-CDB)-that produces nanopores (through thin silicon nitride membranes) surpassing legacy drawbacks associated with solid-state nanopores (SSNs). However, the noise characteristics of CT-CDB nanopores are largely unexplored. In this work, we investigated the 1/f noise of CT-CDB nanopores of varying solution pH, electrolyte type, electrolyte concentration, applied voltage, and pore diameter. Our findings indicate that the bulk Hooge parameter (αb ) is about an order of magnitude greater than SSNs fabricated by transmission electron microscopy (TEM) while the surface Hooge parameter (αs ) is ∼3 order magnitude greater. Theαs of CT-CDB nanopores was ∼5 orders of magnitude greater than theirαb , which suggests that the surface contribution plays a dominant role in 1/f noise. Experiments with DNA exhibited increasing capture rates with pH up to pH ∼8 followed by a drop at pH ∼9 perhaps due to the onset of electroosmotic force acting against the electrophoretic force. The1/f noise was also measured for several electrolytes and LiCl was found to outperform NaCl, KCl, RbCl, and CsCl. The 1/f noise was found to increase with the increasing electrolyte concentration and pore diameter. Taken together, the findings of this work suggest the pH approximate 7-8 range to be optimal for DNA sensing with CT-CDB nanopores.


Subject(s)
Nanopores , DNA , Electrolytes , Electroosmosis , Microscopy, Electron, Transmission
6.
Nanotechnology ; 32(4): 045501, 2021 Jan 22.
Article in English | MEDLINE | ID: mdl-33027774

ABSTRACT

A plasmonic nanopore sensor enabling detection of bimodal optical and electrical molecular signatures was fabricated and tested for its ability to characterize low affinity ligand-receptor interactions. This plasmonic nanosensor uses self-induced back-action (SIBA) for optical trapping to enable SIBA-actuated nanopore electrophoresis (SANE) through a nanopore located immediately below the optical trap volume. A natural killer (NK) cell inhibitory receptor heterodimer molecule CD94/NKG2A was synthesized to target a specific peptide-presenting Qa-1b Qdm ligand as a simplified model of low-affinity interactions between immune cells and peptide-presenting cancer cells that occurs during cancer immunotherapy. A cancer-irrelevant Qa-1b GroEL ligand was also targeted by the same receptor as a control experiment to test for non-specific binding. The analysis of different pairs of bimodal SANE sensor signatures enabled discrimination of ligand, receptor and their complexes and enabled differentiating between specific and non-specific ligand interactions. We were able to detect ligand-receptor complex binding at concentrations over 500 times lower than the free solution equilibrium binding constant (K D ). Additionally, SANE sensor measurements enabled estimation of the fast dissociation rate (k off) for this low-affinity specific ligand-receptor system, previously shown to be challenging to quantify with commercial technologies. The k off value of targeted peptide-presenting ligands is known to correlate with the subsequent activation of immune cells in vivo, suggesting the potential utility of the SANE senor as a screening tool in cancer immunotherapy.


Subject(s)
Electrophoresis , Nanopores , Receptors, Natural Killer Cell , Animals , Electrophoresis/instrumentation , Electrophoresis/methods , Kinetics , Ligands , Mice , Mice, Inbred C57BL , Peptides/chemistry , Peptides/metabolism , Protein Binding , Receptors, Natural Killer Cell/chemistry , Receptors, Natural Killer Cell/metabolism
7.
Biomed Opt Express ; 11(10): 5783-5799, 2020 Oct 01.
Article in English | MEDLINE | ID: mdl-33149986

ABSTRACT

Transcranial photobiomodulation (tPBM) with near-infrared light on the human head has been shown to enhance human cognition. In this study, tPBM-induced effects on resting state brain networks were investigated using 111-channel functional near-infrared spectroscopy over the whole head. Measurements were collected with and without 8-minute tPBM in 19 adults. Functional connectivity (FC) and brain network metrics were quantified using Pearson's correlation coefficients and graph theory analysis (GTA), respectively, for the periods of pre-, during, and post-tPBM. Our results revealed that tPBM (1) enhanced information processing speed and efficiency of the brain network, and (2) increased FC significantly in the frontal-parietal network, shedding light on a better understanding of tPBM effects on brain networks.

8.
Front Neurosci ; 14: 167, 2020.
Article in English | MEDLINE | ID: mdl-32210748

ABSTRACT

Twenty-three young adults (4 Females, 25.13 ± 3.72 years) performed an intermittent maximal handgrip force task using their dominant hand for 20 min (3.5 s squeeze/6.5 s release, 120 blocks) with concurrent cortical activity imaging by functional Near-Infrared Spectroscopy (fNRIS; OMM-3000, Shimadzu Corp., 111 channels). Subjects were grouped as physically active (n = 10) or inactive (n = 12) based on a questionnaire (active-exercise at least four times a week, inactive- exercise less than two times a week). We explored how motor task fatigue affected the vasomotion-induced oscillations in ΔHbO as measured by fNIRS at each hemodynamic frequency band: endothelial component (0.003-0.02 Hz) associated to microvascular activity, neurogenic component (0.02-0.04 Hz) related to intrinsic neuronal activity, and myogenic component (0.04-0.15 Hz) linked to activity of smooth muscles of arterioles. To help understand how these three neurovascular regulatory mechanisms relate to handgrip task performance we quantified several dynamic fNIRS metrics, including directional phase transfer entropy (dPTE), a computationally efficient and data-driven method used as a marker of information flow between cortical regions, and directional connectivity (DC), a means to compute directionality of information flow between two cortical regions. The relationship between static functional connectivity (SFC) and functional connectivity variability (FCV) was also explored to understand their mutual dependence for each frequency band in the context of handgrip performance as fatigued increased. Our findings ultimately showed differences between subject groups across all fNIRS metrics and hemodynamic frequency bands. These findings imply that physical activity modulates neurovascular control mechanisms at the endogenic, neurogenic, and myogenic frequency bands resulting in delayed fatigue onset and enhanced performance. The dynamic cortical network metrics quantified in this work for young, healthy subjects provides baseline measurements to guide future work on older individuals and persons with impaired cardiovascular health.

9.
Neurophotonics ; 6(4): 045011, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31853458

ABSTRACT

The temporal evolution of cortical activation and connectivity patterns during a fatiguing handgrip task were studied by functional near-infrared spectroscopy (fNIRS). Twenty-three young adults (18 to 35 years old) were recruited to use a handheld force sensor to perform intermittent handgrip contractions with their dominant hand at their personal maximum voluntary contraction force level for 3.5 s followed by 6.5 s of rest for 120 blocks. Subjects were divided into self-reported physically active and inactive groups, and their hemodynamic activity over the prefrontal and sensory-motor cortices (111 channels) was mapped while they performed this task. Using this fNIRS setup, a more detailed time sequence of cortical activation and connectivity patterns was observed compared to prior studies. A temporal evolution sequence of hemodynamic activation patterns was noted, which was different between the active and the inactive groups. Physically active subjects demonstrated delayed fatigue onset and significantly longer-lasting and more spatially extended functional connectivity (FC) patterns, compared to inactive subjects. The observed differences in activation and FC suggested differences in cortical network adaptation patterns as fatigue set in, which were dependent on subjects' physical activity. The findings of this study suggest that physical activity increases FC with regions involved in motor task control and correlates to extended fatigue onset and enhanced performance.

10.
Nanotechnology ; 31(8): 085502, 2019 Nov 01.
Article in English | MEDLINE | ID: mdl-31675752

ABSTRACT

Recent advances in plasmonic nanopore technologies have enabled the use of concurrently acquired bimodal optical-electrical data for improved quantification of molecular interactions. This work presents the use of a new plasmonic nanosensor employing self-induced back-action (SIBA) for optical trapping to enable SIBA-actuated nanopore electrophoresis (SANE) for quantifying antibody-ligand interactions. T-cell receptor-like antibodies (TCRmAbs) engineered to target peptide-presenting major histocompatibility complex (pMHC) ligands, representing a model of target ligands presented on the surface of cancer cells, were used to test the SANE sensor's ability to identify specific antibody-ligand binding. Cancer-irrelevant TCRmAbs targeting the same pMHCs were also tested as a control. It was found that the sensor could provide bimodal molecular signatures that could differentiate between antibody, ligand and the complexes that they formed, as well as distinguish between specific and non-specific interactions. Furthermore, the results suggested an interesting phenomenon of increased antibody-ligand complex bound fraction detected by the SANE sensor compared to that expected for corresponding bulk solution concentrations. A possible physical mechanism and potential advantages for the sensor's ability to augment complex formation near its active sensing volume at concentrations lower than the free solution equilibrium binding constant (K D ) are discussed.

11.
Biomed Opt Express ; 9(11): 5296-5317, 2018 Nov 01.
Article in English | MEDLINE | ID: mdl-30460129

ABSTRACT

Little work has been done on the information flow in functional brain imaging and none so far in fNIRS. In this work, alterations in the directionality of net information flow induced by a short-duration, low-current (2 min 40 s; 0.5 mA) and a longer-duration, high-current (8 min; 1 mA) anodal tDCS applied over the Broca's area of the dominant language hemisphere were studied by fNIRS. The tDCS-induced patterns of information flow, quantified by a novel directed phase transfer entropy (dPTE) analysis, were distinct for different hemodynamic frequency bands and were qualitatively similar between low and high-current tDCS. In the endothelial band (0.003-0.02 Hz), the stimulated Broca's area became the strongest hub of outgoing information flow, whereas in the neurogenic band (0.02-0.04 Hz) the contralateral homologous area became the strongest information outflow source. In the myogenic band (0.04-0.15 Hz), only global patterns were seen, independent of tDCS stimulation that were interpreted as Mayer waves. These findings showcase dPTE analysis in fNIRS as a novel, complementary tool for studying cortical activity reorganization after an intervention.

12.
Nanotechnology ; 29(43): 435501, 2018 Oct 26.
Article in English | MEDLINE | ID: mdl-30073973

ABSTRACT

We present a novel method to trap nanoparticles in double nanohole (DNH) nanoapertures integrated on top of solid-state nanopores (ssNP). The nanoparticles were propelled by an electrophoretic force from the cis towards the trans side of the nanopore but were trapped in the process when they reached the vicinity of the DNH-ssNP interface. The self-induced back action (SIBA) plasmonic force existing between the tips of the DNH opposed the electrophoretic force and enabled simultaneous optical and electrical sensing of a single nanoparticle for seconds. The novel SIBA actuated nanopore electrophoresis (SANE) sensor was fabricated using two-beam GFIS FIB. Firstly, Ne FIB milling was used to create the DNH features and was combined with end pointing to stop milling at the metal-dielectric interface. Subsequently, He FIB was used to drill a 25 nm nanopore through the center of the DNH. Proof of principle experiments to demonstrate the potential utility of the SANE sensor were performed with 20 nm silica and Au nanoparticles. The addition of optical trapping to electrical sensing extended translocation times by four orders of magnitude. The extended electrical measurement times revealed newly observed high frequency charge transients that were attributed to bobbing of the nanoparticle driven by the competing optical and electrical forces. Frequency analysis of this bobbing behavior hinted at the possibility of distinguishing single from multi-particle trapping events. We also discuss how SANE sensor measurement characteristics differ between silica and Au nanoparticles due to differences in their physical properties and how to estimate the charge around a nanoparticle. These measurements show promise for the SANE sensor as an enabling tool for selective detection of biomolecules and quantification of their interactions.

13.
J Environ Manage ; 223: 165-174, 2018 Oct 01.
Article in English | MEDLINE | ID: mdl-29929072

ABSTRACT

Stakeholder engagement in the processes of planning local adaptation to climate change faces many challenges. The goal of this work was to explore whether or not the intention of engaging could be understood (Study 1) and promoted (Study 2), by using an extension of the theory of planned behaviour. In Study 1, stakeholders from three European Mediterranean case studies were surveyed: Baixo Vouga Lagunar (Portugal), SCOT Provence Méditerranée (France), and the island of Crete (Greece) (N = 115). Stakeholders' intention of engaging was significantly predicted by subjective norm (which was predicted by injunctive normative beliefs towards policy-makers and stakeholders) and by perceived behavioural control (which was predicted by knowledge of policy and instruments). Study 2 was conducted in the Baixo Vouga Lagunar case study and consisted of a two-workshop intervention where issues on local and regional adaptation, policies, and engagement were presented and discussed. A within-participants comparison of initial survey results with results following the workshops (NT1 = 12, NT2 = 15, NT3 = 12) indicated that these were successful in increasing stakeholders' intention of engaging. This increase was paired with a) an increase in injunctive normative beliefs towards policy-makers and consequently in subjective norm, and to b) a decrease in perceived complexity of planning local adaptation and an increase in knowledge regarding adaptation to climate change.


Subject(s)
Climate Change , Intention , France , Greece , Humans , Policy Making , Portugal
14.
Neurophotonics ; 5(2): 025002, 2018 Apr.
Article in English | MEDLINE | ID: mdl-29531963

ABSTRACT

Cortical circuit reorganization induced by anodal transcranial direct current stimulation (tDCS) over the Broca's area of the dominant language hemisphere in 13 healthy adults was quantified by functional near-infrared spectroscopy (fNIRS). Transient cortical reorganization patterns in steady-state functional connectivity (seed-based and graph theory analysis) and temporal functional connectivity (sliding window correlation analysis) were recorded before, during, and after applying high current tDCS (1 mA, 8 min). fNIRS connectivity mapping showed that tDCS induced significantly ([Formula: see text]) increased functional connectivity between Broca's area and its neighboring cortical regions while it simultaneously decreased the connectivity to remote cortical regions. Furthermore, the anodal stimulation caused significant increases to the functional connectivity variability (FCV) of remote cortical regions related to language processing. In addition to the high current tDCS, low current tDCS (0.5 mA, 2 min 40 s) was also applied to test whether the transient effects of lower stimulation current could qualitatively predict cortical connectivity alterations induced by the higher currents. Interestingly, low current tDCS could qualitatively predict the increase in clustering coefficient and FCV but not the enhancement of local connectivity. Our findings indicate the possibility of combining future studies fNIRS with tDCS at lower currents to help guide therapeutic interventions.

15.
Cancer Genet ; 220: 19-23, 2018 01.
Article in English | MEDLINE | ID: mdl-29310834

ABSTRACT

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant disorder caused by germline mutations in the STK11 tumor suppressor gene. PJS patients face a cumulative cancer risk as high as 93% for all sites combined. The present study reports the spectrum of STK11 mutations in eight families with clinical diagnosis of PJS, summarizes the clinical characteristics of sixteen mutation carriers and launches a National Registry for PJS in Greece. STK11 loss-of-function (LoF) mutations were detected in 87.5% of index patients. Carriers presented with their first manifestation at a median age of 24.9 years, while early-onset breast cancer was the most frequent malignancy observed, highlighting the need for breast surveillance. Out of the deleterious STK11 mutations identified, two were novel: c.375_376delGT and c.676_679dupAACG, with 57.2% of these potentially occurring de novo. Using all available clinical and genetic data, the National Registry for Greek PJS was established in an attempt to better characterize the syndrome and raise awareness among patients and clinicians (available at https://www.peutzjeghersgreece.org). This is the first comprehensive genetic analysis and clinical characterization of Greek PJS patients, where a high incidence of breast cancer was observed and the first attempt to centralize all data in a National Registry.


Subject(s)
Genetic Testing/methods , Peutz-Jeghers Syndrome/genetics , Adult , Female , Greece , Humans , Male , Peutz-Jeghers Syndrome/pathology , Registries , Young Adult
16.
Endoscopy ; 49(11): 1051-1060, 2017 Nov.
Article in English | MEDLINE | ID: mdl-28763808

ABSTRACT

Background and study aims The Endocuff (ARC Medical Design, Leeds, UK) is a device that, when mounted on the tip of an endoscope, may assist with inspection of a greater surface of the colonic mucosa by pulling backwards, flattening, and stretching the colonic folds as the endoscope is gradually withdrawn. We aimed to compare the adenoma miss rates of Endocuff-assisted colonoscopy with those of conventional colonoscopy. Patients and methods The included patients underwent same-day, back-to-back, (Endocuff-assisted colonoscopy as the index procedure followed by conventional colonoscopy or vice versa, randomly assigned 1:1) colonoscopies, performed by six endoscopists with documented adenoma detection rates > 35 %, in four tertiary endoscopy facilities. Results We randomized 200 patients (mean age 61.2 years [standard deviation 9.8]; 86.5 % colorectal cancer screening surveillance cases). Overall, there were seven incomplete examinations using Endocuff and one with conventional colonoscopy (P = 0.03). Times for endoscope insertion (5.0 minutes [0.8 - 21.0] vs. 5.0 minutes [1.0 - 16.0]; P = 0.49) and withdrawal (6.0 minutes [3.2 - 29.0] vs. 6.0 minutes [3.1 - 17.0]; P = 0.06) were similar for Endocuff-assisted and conventional colonoscopy. We detected one cancer and 195 adenomas; 84 in the proximal colon. Endocuff-assisted colonoscopy showed significantly lower overall and proximal colon adenoma miss rates compared with conventional colonoscopy (14.7 % [8.0 % - 21.0 %] vs. 38.4 % [28.1 % - 48.6 %] and 10.4 % [1.8 % - 19.1 %] vs. 38.9 % [23.0 % - 54.8 %], respectively). No difference between the two arms was shown regarding advanced adenoma miss rates, either overall or in the proximal colon. There were no serious adverse events related to the procedures. Conclusions In comparison with conventional colonoscopy, Endocuff-assisted colonoscopy has a significantly lower adenoma miss rate when performed by high-detector endoscopists. However, the incomplete colonoscopy rate with Endocuff is higher.ClinicalTrials.gov Identifier: NCT02340065.


Subject(s)
Adenoma/diagnostic imaging , Colonic Polyps/diagnostic imaging , Colonoscopy/instrumentation , Colorectal Neoplasms/diagnostic imaging , Population Surveillance , Aged , Cecum/diagnostic imaging , Colon, Ascending/diagnostic imaging , Colon, Transverse/diagnostic imaging , Colonoscopy/adverse effects , Cross-Over Studies , Early Detection of Cancer/instrumentation , False Negative Reactions , Female , Humans , Male , Middle Aged , Time Factors
17.
Eur J Gastroenterol Hepatol ; 29(2): 185-191, 2017 Feb.
Article in English | MEDLINE | ID: mdl-27775952

ABSTRACT

INTRODUCTION: Since its introduction, small bowel video capsule endoscopy (VCE) use has evolved considerably. AIM: Evaluation of the temporal changes of small bowel VCE utilization in three tertiary centers in Greece in Era 1 (2002-2009) and Era 2 (2010-2014) and the development a forecast model for future VCE use during 2015-2017. MATERIALS AND METHODS: Data from all small bowel VCE examinations were retrieved and analyzed in terms of the annual number of the performed examinations, their indications and the significance of their findings. RESULTS: Overall, we evaluated 3724 VCE examinations. The number of studies peaked in 2009 (n=595) and then decreased to reach 225 in 2014. Overall, more (53.8 vs. 51.4%) patients with iron-deficiency anemia and obscure gastrointestinal bleeding (IDA/OGIB) and fewer (10.7 vs. 14%) patients with chronic diarrhea were evaluated in Era 2 compared with Era 1 (P=0.046). In Era 2, there were more nondiagnostic examinations (39.5 vs. 29.3%, P<0.001), whereas the rate of cases with relevant findings decreased from 47.8 to 40.9%. According to the time trend analysis, we developed a forecast model with two scenarios: the pessimistic and the optimistic. Validation of the model with 2015 data showed that reality was close to the pessimistic scenario: the number of exams further decreased to 190, studies carried out for IDA/OGIB increased to 67%, and there were more negative than positive exams (40.7 vs. 39.2%). CONCLUSION: The number of VCE studies carried out after the emergence of the financial crisis decreased significantly and VCE indications were optimized. Our forecast model predicts lower numbers of VCE studies, with IDA/OGIB being the dominant indication. However, the predicted increase of negative exams requires further evaluation.


Subject(s)
Anemia, Iron-Deficiency/diagnosis , Capsule Endoscopy/trends , Crohn Disease/diagnosis , Diarrhea/diagnosis , Economic Recession , Gastrointestinal Hemorrhage/diagnosis , Intestine, Small , Aged , Chronic Disease , Female , Forecasting , Greece , Humans , Male , Middle Aged , Prospective Studies , Reproducibility of Results , Retrospective Studies , Tertiary Care Centers
18.
Biomed Opt Express ; 6(9): 3256-67, 2015 Sep 01.
Article in English | MEDLINE | ID: mdl-26417498

ABSTRACT

Near infrared spectroscopy (NIRS) is capable of detecting and monitoring acute changes in cerebral blood volume and oxygenation associated with traumatic brain injury (TBI). Wavelength selection, source-detector separation, optode density, and detector sensitivity are key design parameters that determine the imaging depth, chromophore separability, and, ultimately, clinical usefulness of a NIRS instrument. We present simulation results of NIR light propagation in a digital head model as it relates to the ability to detect intracranial hematomas and monitor the peri-hematomal tissue viability. These results inform NIRS instrument design specific to TBI diagnosis and monitoring.

19.
J Fluoresc ; 25(6): 1775-85, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26411799

ABSTRACT

Photobleaching is a key limitation in two-photon imaging of fluorescent proteins with femtosecond pulsed excitation. We present measurements of the dependence of eGFP photobleaching on the spectral amplitude and phase of the pulses used. A strong dependence on the excitation wavelength was confirmed and measured over a 800-950 nm range. A fiber continuum light source and pulse shaping techniques were used to investigate photobleaching with broadband, 15 fs transform limited, pulses with differing spectral amplitude and phase. Narrow band pulses, >150 fs transform limited, typical of femtosecond laser sources used in two-photon imaging applications, were also investigated for their photobleaching dependence on pulse dispersion and bandwidth. The bleach rate for broadband pulses was found to be primarily determined by the second harmonic spectrum of the excitation light. On the other hand, for narrow band excitation pulses with similar center wavelengths improvement in bleach rate was found to be mostly dependent on reducing the pulse length. A simple model to predict the relative bleach rates for broadband pulses is presented and compared to the experimental data.


Subject(s)
Green Fluorescent Proteins/chemistry , Photobleaching , Photons , Kinetics , Lasers , Spectrometry, Fluorescence
20.
J Biomed Opt ; 20(4): 046009, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25900145

ABSTRACT

Sensorimotor cortex plasticity induced by constraint-induced movement therapy (CIMT) in six children (10.2±2.1 years old) with hemiplegic cerebral palsy was assessed by functional near-infrared spectroscopy (fNIRS). The activation laterality index and time-to-peak/duration during a finger-tapping task and the resting-state functional connectivity were quantified before, immediately after, and 6 months after CIMT. These fNIRS-based metrics were used to help explain changes in clinical scores of manual performance obtained concurrently with imaging time points. Five age-matched healthy children (9.8±1.3 years old) were also imaged to provide comparative activation metrics for normal controls. Interestingly, the activation time-to-peak/duration for all sensorimotor centers displayed significant normalization immediately after CIMT that persisted 6 months later. In contrast to this improved localized activation response, the laterality index and resting-state connectivity metrics that depended on communication between sensorimotor centers improved immediately after CIMT, but relapsed 6 months later. In addition, for the subjects measured in this work, there was either a trade-off between improving unimanual versus bimanual performance when sensorimotor activation patterns normalized after CIMT, or an improvement occurred in both unimanual and bimanual performance but at the cost of very abnormal plastic changes in sensorimotor activity.


Subject(s)
Brain Mapping/methods , Cerebral Palsy/physiopathology , Cerebral Palsy/therapy , Neuronal Plasticity , Sensorimotor Cortex/physiopathology , Spectroscopy, Near-Infrared/methods , Child , Female , Humans , Male , Motion Therapy, Continuous Passive , Oxygen Consumption , Reproducibility of Results , Sensitivity and Specificity , Treatment Outcome
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