Flexible gastrointestinal motility pressure sensors based on aluminum thin-film strain-gauge arrays

This paper reports on an innovative approach to measuring intraluminal pressure in the upper gastrointestinal (GI) tract, especially monitoring GI motility and peristaltic movements. The proposed approach relies on thin-film aluminum strain gauges deposited on top of a Kapton membrane, which in turn lies on top of an SU-8 diaphragm-like structure. This structure enables the Kapton membrane to bend when pressure is applied, thereby affecting the strain gauges and effectively changing their electrical resistance. The sensor, with an area of 3.4 mm2, is fabricated using photolithography and standard microfabrication techniques (wet etching). It features a linear response (R2 = 0.9987) and an overall sensitivity of 2.6 mV mmHg−1. Additionally, its topology allows a high integration capability. The strain gauges’ responses to pressure were studied and the fabrication process optimized to achieve high sensitivity, linearity, and reproducibility. The sequential acquisition of the different signals is carried out by a microcontroller, with a 10-bit ADC and a sample rate of 250 Hz. The pressure signals are then presented in a user-friendly interface, developed using the Integrated Development Environment software, QtCreator IDE, for better visualization by physicians.

Deteção e classificação de regiões de interesse em vídeos de endoscopia

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Informática Médica)

Prognostic value of technetium-99m-labeled single-photon emission computerized tomography in the follow-up of patients after their first myocardial revascularization surgery

OBJECTIVE: To assess the prognostic value of Technetium-99m-labeled single-photon emission computerized tomography (SPECT) in the follow-up of patients who had undergone their first myocardial revascularization. METHODS: We carried out a retrospective study of 280 revascularized patients undergoing myocardial scintigraphy under stress (exercise or pharmacological stress with dipyridamole) and at rest according to a 2-day protocol. A set of clinical, stress electrocardiographic and scintigraphic variables was assessed. Cardiac events were classified as "major" (death, infarction, unstable angina) and "any" (major event or coronary angioplasty or new myocardial revascularization surgery). RESULTS: Thirty-six major events occurred as follows: 3 deaths, 11 infarctions, and 22 unstable anginas. In regard to any event, 22 angioplasties and 7 new surgeries occurred in addition to major events, resulting a total of 65 events. The sensitivity of scintigraphy in prognosticating a major event or any event was, respectively, 55% and 58%, showing a negative predictive value of 90% and 83%, respectively. Diabetes mellitus, inconclusive stress electrocardiography, and a scintigraphic visualization of left ventricular enlargement were significant variables for the occurrence of a major event. On multivariate analysis, abnormal myocardial scintigraphy was a predictor of any event. CONCLUSION: Myocardial perfusion tomography with Technetium-99m may be used to identify high-risk patients after their first myocardial revascularization surgery.

Ultrasound Blocks for the Anterior Abdominal Wall - Adult and Pediatric Surgery

Somatic post-surgical pain is invalidating and distressing to patients and carries the risk of important complications. The anterior abdominal wall is involved in most surgical procedures in general, gynecologic, obstetric, urological, vascular and pediatric surgery. Combined multimodal strategies involving nerve blocks, opiates, and non-steroidal anti-inflammatory drugs for systemic analgesia are necessary for optimal pain modulation. Anterior abdominal wall blocks, transverse abdominal plexus block, iliohypogastric and ilioinguinal nerveblock, genitofemoral nerve block and rectus sheath block have an important role as components of multimodal analgesia for somatic intraoperative and postoperative pain control. Ultrasound visualization has improved the efficacy and safety of abdominal blocks and implemented the application in the clinical setting. For this reason, they are a very important tool for all anesthesiologists who aim to treat effectively patients’ pain. This guide provides an evidence based comprehensive and necessary overview of anatomical, anesthesiological and technical information needed to safely perform these blocks.

Analysis of the Atmosphere Aerosol and Ozone Condition Over Tbilisi Using Satellite Data and Ground Truth Measurements

Ground-based measurements of the parameters of atmosphere in Tbilisi during the same period, which are provided by the Mikheil Nodia Institute of geophysics, were used as calibration data. Satellite data monthly averaging, preprocessing, analysis and visualization was performed using Giovanni web-based application. Maps of trends and periodic components of the atmosphere aerosol optical thickness and ozone concentration over the study area were calculated.

Informationsdarstellung mit Bildern

Visualization, information visualization, computer graphics, non-photorealistic rendering

Extraction of topological structures in 2D and 3D vector fields

feature extraction, feature tracking, vector field visualization

Use of camera-traps in natural trails and shelters for the mammalian survey in the Atlantic Forest

In order to evaluate the efficiency of different mammalian survey methods, we compared traditional sampling techniques (use of camera-traps on roads and artificial trails, track censuses, and direct field visualization) with an alternative sampling design (camera-traps positioned in natural areas such as natural trails and shelters). We conducted the study in a deciduous Atlantic-Forest park in southern Brazil, and additionally compared our results with a previous intensive study carried out in the same area. Our considerably smaller sampling effort (example: 336 trap.day for our camera-traps versus 2,154 trap.day for the earlier study) registered the presence of 85% of the local known species, with camera-traps being 68% efficient. Moreover, shelter camera-traps revealed a different species composition regarding most of other sampling methods. This sampling strategy involving natural forest sites was therefore able to effectively optimize the chances of evaluating species composition in a shorter period, especially with respect to lower-density and cryptic species, as well as to detect species that avoid open, disturbed sites such as roads and man-made forest trails.

Desenvolupament de mesures per comparar transculturalment xarxes personals (USA i Estats Units)

Estudi elaborat a partir d’una estada a la Universitat de Florida durant Abril i Maig de 2006. “Application to Immigrant Populations in South Florida and Northeastern Spain" ha permès recollir les xarxes personals d’immigrants en els dos països mitjançant un qüestionari implementat amb un software desenvolupat ex professo per recollir i presentar visualment les dades. Es van revisar i assemblar les entrevistes i qüestionaris realitzats a Catalunya i a Estats Units (Miami i Nova York, especialment). Fins al moment s’han revisat i analitzat uns 450 casos. Un cop depurada i analitzada la informació obtinguda s’ha pogut disposar per primer cop de mesures globals pels diferents col•lectius estudiats. L'objectiu global del projecte és entendre les implicacions que les estructures de les xarxes personals tenen en relació a un conjunt de conductes (de salut, d'ús de la llengua, etx) i les autoconcepcions. En aquest sentit era necessari desenvolupar un seguit de mesures que permetessin comparar i documentar la variació de les estructures de les xarxes personals a diferents cultures, nivells socioeconòmics, gènere, religió, etc. i incorporar-les com a variables independents als models explicatius.En aquest moments s’està desenvolupant un índex basat en variables estructurals (número de components de la xarxa, densitat, grau d’intermediació, etc.) i variables de composició (proporció de persones diferents del país d’origen, entre d'altres). La idea és disposar d’un índex d’heterogeneïtat de la xarxa social comparable entre els diferents col•lectius. Malgrat que el treball continua, la principal conclusió a la que s’ha arribat és que al menys a Espanya a mida que passa el temps augmenta el nivell d’heterogeneïtat de les xarxes personals. És a dir, que desprès d’un ràpid procés de canvi i una fase de transnacionalitat la tendència és a reduir aquest nivell (pels costos socials i econòmics que comporta) depenent, naturalment, de factors com l’origen temporal (primera onada o successives), el tipus de col•lectiu i el sexe.

Differentiation of the sibling species Biomphalaria occidentalis and Biomphalaria tenagophila by the electrophoretic patterns of their hemoglobin

A simple and rapid method for differentialing the sibling species Biomphalaria tenagophila and Biomphalaria occidentalis by agarose gel electrophoresis (AGE) is described. Snail hemolymph is used as the test sample and the red colaration of the hemoglobin fraction permits visualization of the migration patterns without resorting to specific stains. Moreover, hemolymph samples may be obtained without killing the snail, thus permitting its use for other studies for breeding.

Multi-phase post-mortem CT angiography: development of a standardized protocol.

The objective of this work was to develop an easily applicable technique and a standardized protocol for high-quality post-mortem angiography. This protocol should (1) increase the radiological interpretation by decreasing artifacts due to the perfusion and by reaching a complete filling of the vascular system and (2) ease and standardize the execution of the examination. To this aim, 45 human corpses were investigated by post-mortem computed tomography (CT) angiography using different perfusion protocols, a modified heart-lung machine and a new contrast agent mixture, specifically developed for post-mortem investigations. The quality of the CT angiographies was evaluated radiologically by observing the filling of the vascular system and assessing the interpretability of the resulting images and by comparing radiological diagnoses to conventional autopsy conclusions. Post-mortem angiography yielded satisfactory results provided that the volumes of the injected contrast agent mixture were high enough to completely fill the vascular system. In order to avoid artifacts due to the post-mortem perfusion, a minimum of three angiographic phases and one native scan had to be performed. These findings were taken into account to develop a protocol for quality post-mortem CT angiography that minimizes the risk of radiological misinterpretation. The proposed protocol is easy applicable in a standardized way and yields high-quality radiologically interpretable visualization of the vascular system in post-mortem investigations.

Videolaryngoscopy improves intubation condition in morbidly obese patients

Résumé : Contexte clinique et objectifs: l'intubation oro-trachéale peut être plus difficile chez les patients obèses morbides (index de masse corporelle BMI > 35 kg/m2) que chez les patients non-obèses. Récemment, de nouveaux instruments permettant une intubation assistée au moyen d'une caméra ont été développés. Notre expérience pratique avec la vidéolaryngoscopie nous a conduit à l'hypothèse que celle-ci pourrait améliorer la vision laryngoscopique chez cette population spécifique et de ce fait faciliter l'intubation. Le but de cette étude était donc d'évaluer le bénéfice du vidéolaryngoscope sur le grade de laryngoscopie chez le patient obèse morbide. Résultats : le grade laryngoscopique fut abaissé de manière significative avec le vidéolaryngoscope comparé à la vision directe avec un laryngoscope standard. Lorsque le grade laryngoscopique était plus grand que 1 à la laryngoscopie directe, il fut dans la grande majorité des cas (93% des patients) abaissé avec le vidéolaryngoscope. Chez les 7 % restant, le grade laryngoscopique resta identique. Conclusions : chez le patient obèse morbide, l'utilisation du vidéolaryngoscope améliore de manière significative la visualisation du larynx et de ce fait facilite l'intubation. Une application systématique de ce procédé pourrait donc permettre de réduire l'incidence d'une intubation difficile ainsi que ses conséquences chez cette population de patients. Summary : Background and objective: Tracheal intubation may be more difficult in morbidly obese patients (body mass index >35 kgM-2) than in the non-obese. Recently, new video-assisted intubation devices have been developed. After some experience with videolaryngoscopy, we hypothesized that it could improve the laryngoscopic view in this specific population and therefore facilitate intubation. The aim of this study was to assess the benefit of a videolaryngoscope on the grade of laryngoscopy in morbid obesity. Methods: We studied 80 morbidly obese patients undergoing bariatric surgery. They were randomly assigned to one of two groups. One group was intubated with the help of the videolaryngoscope and in the control group the screen of the videolaryngoscope was hidden to the intubating anaesthesiologist. The primary end-point of the study was to assess in both groups the Cormack and Lehane direct and indirect grades of laryngoscopy. The duration of intubation, the number of attempts needed as well as the minimal SPO2 reached during the intubation process were measured. Results: Grade of laryngoscopy was significantly lower with the videolaryngoscope compared with the direct vision (P < 0.001). When the grade of laryngoscopy was higher than one with the direct laryngoscopy (n = 30), it was lower in 28 cases with the videolaryngoscope and remained the same only in two cases (P < 0.001). The minimal SPO2 reached during the intubation was higher with the videolaryngoscope but it did not reach statistical significance. Conclusions: In morbidly obese patients, the use of the videolaryngoscope significantly improves the visualization of the larynx and thereby facilitates intubation.

Ischemic heart disease in postmortem CT and CT angiography

Objective: Postmortem radiology had in recent years appeared in the field of forensic medicine and is now considered by some authors as a good replacement for conventional autopsy and by others as a complementary examination. Although postmortem CT radiological imaging is very useful in demonstrating traumatic lesions, its utility is still quite limited in the cardiovascular field. This limitation could be minimized by the introduction of postmortem angiography. At the University Center of Legal Medicine of Lausanne, CT scans and postmortem multiphase CTangiography are used in cases with a suspicion of ischemic heart disease.Method: The goal of this presentation is to demonstrate some correlations between postmortem CT, CTangiography and conventional autopsy examination in cases of ischemic heart disease.Results: We observed that the native CT scan can show only some pathological findings as cardiac tamponade and calcifications of coronary arteries. However, postmortem angiography allows a better visualization of coronary arteries and evaluation of stenosis and occlusion as well as better imaging of soft tissue.Conclusion: The interpretation of postmortem modern radiology is a new field for both forensic pathologists and radiologists who have to learn to read the postmortem modified images. The information obtained from both parties can help to further the understanding of CT and CT angiography in postmortem cases.

Subcellular investigation of photosynthesis-driven carbon assimilation in the symbiotic reef coral Pocillopora damicornis.

Reef-building corals form essential, mutualistic endosymbiotic associations with photosynthetic Symbiodinium dinoflagellates, providing their animal host partner with photosynthetically derived nutrients that allow the coral to thrive in oligotrophic waters. However, little is known about the dynamics of these nutritional interactions at the (sub)cellular level. Here, we visualize with submicrometer spatial resolution the carbon and nitrogen fluxes in the intact coral-dinoflagellate association from the reef coral Pocillopora damicornis by combining nanoscale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy with pulse-chase isotopic labeling using [(13)C]bicarbonate and [(15)N]nitrate. This allows us to observe that (i) through light-driven photosynthesis, dinoflagellates rapidly assimilate inorganic bicarbonate and nitrate, temporarily storing carbon within lipid droplets and starch granules for remobilization in nighttime, along with carbon and nitrogen incorporation into other subcellular compartments for dinoflagellate growth and maintenance, (ii) carbon-containing photosynthates are translocated to all four coral tissue layers, where they accumulate after only 15 min in coral lipid droplets from the oral gastroderm and within 6 h in glycogen granules from the oral epiderm, and (iii) the translocation of nitrogen-containing photosynthates is delayed by 3 h. IMPORTANCE: Our results provide detailed in situ subcellular visualization of the fate of photosynthesis-derived carbon and nitrogen in the coral-dinoflagellate endosymbiosis. We directly demonstrate that lipid droplets and glycogen granules in the coral tissue are sinks for translocated carbon photosynthates by dinoflagellates and confirm their key role in the trophic interactions within the coral-dinoflagellate association.

Endovascular thoracic aortic aneurysm repair without angiography.

OBJECTIVE: : Intravascular ultrasound (IVUS) generates high definition circumferential cross-sectional images and provides real-time readout of vascular dimensions, including visualization of vessel branches. We have used it as an alternative to angiography in the endovascular thoracic aneurysm repair work-up. METHODS: : Out of consecutive 203 patients with descending thoracic aortic aneurysm, 89 (43.8%) received endovascular treatment [mean age, 68 ± 8 years; range, 29-82; male, 79 (88.7%); female, 10 (11.3%)] without using angiography during the endovascular procedure. IVUS (6 F, 12.5 MHz probe or 10 F 9 MHz) coupled with fluoroscopy for the placement of radiopaque markers was used for target site identification, landing zone measurement, device positioning, and assessment of endovascular repair. RESULTS: : Hospital mortality was 4/89 (4.5%). Number of devices implanted in each patient was 1.2 (range, 1-3). X-ray exposure time was 12 ± 8 minutes. Median procedure time was 63 ± 20 minutes. Conversion to open surgery was necessary in one patient (1.1%) because of aortic dissection. In nine patients (10.1%) left subclavian artery was covered because of a short neck. Two patients (2.2%) had vascular access lesions and required surgical repair. One patient developed paraplegia (1.1%). Early endoleak was observed in eight patients (8.9%) and 4 (4.5%) required additional procedures (proximal or distal extensions). Late conversion was necessary in one patient (1.1%). CONCLUSIONS: : IVUS provides all information necessary for device selection, target site identification as well as safe and correct deployment of thoracic endoprostheses and makes periprocedural angiography unnecessary, thus avoiding the risk of renal failure because of contrast medium.