Current Issue : April - June Volume : 2012 Issue Number : 2 Articles : 8 Articles
It has traditionally been assumed that cochlear implant users de facto perform atypically in audiovisual tasks. However, a\r\nrecent study that combined an auditory task with visual distractors suggests that only those cochlear implant users that are\r\nnot proficient at recognizing speech sounds might show abnormal audiovisual interactions. The present study aims at\r\nreinforcing this notion by investigating the audiovisual segregation abilities of cochlear implant users in a visual task with\r\nauditory distractors. Speechreading was assessed in two groups of cochlear implant users (proficient and non-proficient at\r\nsound recognition), as well as in normal controls. A visual speech recognition task (i.e. speechreading) was administered\r\neither in silence or in combination with three types of auditory distractors: i) noise ii) reverse speech sound and iii) nonaltered\r\nspeech sound. Cochlear implant users proficient at speech recognition performed like normal controls in all\r\nconditions, whereas non-proficient users showed significantly different audiovisual segregation patterns in both speech\r\nconditions. These results confirm that normal-like audiovisual segregation is possible in highly skilled cochlear implant users\r\nand, consequently, that proficient and non-proficient CI users cannot be lumped into a single group. This important feature\r\nmust be taken into account in further studies of audiovisual interactions in cochlear implant users....
Neuronal degeneration and the deterioration of neuronal communication lie at the origin of many neuronal disorders, and\nthere have been major efforts to develop cell replacement therapies for treating such diseases. One challenge, however, is\nthat differentiated cells are challenging to transplant due to their sensitivity both to being uprooted from their cell culture\ngrowth support and to shear forces inherent in the implantation process. Here, we describe an approach to address these\nproblems. We demonstrate that rat hippocampal neurons can be grown on colloidal particles or beads, matured and even\ntransfected in vitro, and subsequently transplanted while adhered to the beads into the young adult rat hippocampus. The\ntransplanted cells have a 76% cell survival rate one week post-surgery. At this time, most transplanted neurons have left\ntheir beads and elaborated long processes, similar to the host neurons. Additionally, the transplanted cells distribute\nuniformly across the host hippocampus. Expression of a fluorescent protein and the light-gated glutamate receptor in the\ntransplanted neurons enabled them to be driven to fire by remote optical control. At 1-2 weeks after transplantation,\ncalcium imaging of host brain slice shows that optical excitation of the transplanted neurons elicits activity in nearby host\nneurons, indicating the formation of functional transplant-host synaptic connections. After 6 months, the transplanted cell\nsurvival and overall cell distribution remained unchanged, suggesting that cells are functionally integrated. This approach,\nwhich could be extended to other cell classes such as neural stem cells and other regions of the brain, offers promising\nprospects for neuronal circuit repair via transplantation of in vitro differentiated, genetically engineered neurons....
Multielectrodes have been used with great success to simultaneously record the activity of neuronal populations in awake,\nbehaving animals. In particular, there is great promise in the use of this technique to allow the control of neuroprosthetic\ndevices by human patients. However, it is crucial to fully characterize the tissue response to the chronic implants in animal\nmodels ahead of the initiation of human clinical trials. Here we evaluated the effects of unilateral multielectrode implants on\nthe motor cortex of rats weekly recorded for 1ââ?¬â??6 months using several histological methods to assess metabolic markers,\ninflammatory response, immediate-early gene (IEG) expression, cytoskeletal integrity and apoptotic profiles. We also\ninvestigated the correlations between each of these features and firing rates, to estimate the impact of post-implant time\non neuronal recordings. Overall, limited neuronal loss and glial activation were observed on the implanted sites. Reactivity\nto enzymatic metabolic markers and IEG expression were not significantly different between implanted and non-implanted\nhemispheres. Multielectrode recordings remained viable for up to 6 months after implantation, and firing rates correlated\nwell to the histochemical and immunohistochemical markers. Altogether, our results indicate that chronic tungsten\nmultielectrode implants do not substantially alter the histological and functional integrity of target sites in the cerebral\ncortex....
Background: Peri-implantitis has gained significant clinical attention in recent years. This disease is an inflammatory\nreaction to microorganisms around dental implants. Due to the limited accessibility, non-invasive antimicrobial strategies\nare of high interest. An unexpected approach to implant disinfection may evolve from electrolysis. Given the electrical\nconductivity of titanium implants, alkalinity or active oxidants can be generated in body fluids. We investigated the use of\ndental titanium implants as electrodes for the local generation of disinfectants. Our hypothesis was that electrolysis can\nreduce viable counts of adhering bacteria, and that this reduction should be greater if active oxidative species are\ngenerated.\nMethodology/Principal Findings: As model systems, dental implants, covered with a mono-species biofilm of Escherichia\ncoli C43, were placed in photographic gelatin prepared with physiological saline. Implants were treated by a continuous\ncurrent of 0 - 10 mA for 15 minutes. The reduction of viable counts was investigated on cathodes and anodes. In separate\nexperiments, the local change in pH was visualized using color indicators embedded in the gelatin. Oxidative species were\nqualitatively detected by potassium iodide-starch paper. The in situ generated alkaline environment around cathodic\nimplants caused a reduction of up to 2 orders of magnitude in viable E. coli counts. On anodic implants, in contrast to\ncathodic counterparts, oxidative species were detected. Here, a current of merely 7.5 mA caused complete kill of the\nbacteria.\nConclusions/Significance: This laboratory study shows that electrochemical treatment may provide access to a new way to\ndecontaminate dental implants in situ....
Objectives: To identify genetic factors that would be predictive of individuals who require an implantable cardioverterdefibrillator\n(ICD), we conducted a genome-wide association study among individuals with an ICD who experienced a lifethreatening\narrhythmia (LTA; cases) vs. those who did not over at least a 3-year period (controls).\nBackground: Most individuals that receive implantable cardioverter-defibrillators never experience a life-threatening\narrhythmia. Genetic factors may help identify who is most at risk.\nMethods: Patients with an ICD and extended follow-up were recruited from 34 clinical sites with the goal of oversampling\nthose who had experienced LTA, with a cumulative 607 cases and 297 controls included in the analysis. A total of 1,006\nCaucasian patients were enrolled during a time period of 13 months. Arrhythmia status of 904 patients could be confirmed\nand their genomic data were included in the analysis. In this cohort, there were 704 males, 200 females, and the average age\nwas 73.3 years. We genotyped DNA samples using the Illumina Human660 W Genotyping BeadChip and tested for\nassociation between genotype at common variants and the phenotype of having an LTA.\nResults and Conclusions: We did not find any associations reaching genome-wide significance, with the strongest\nassociation at chromosome 13, rs11856574 at P = 561026. Loci previously implicated in phenotypes such as QT interval\n(measure of the time between the start of the Q wave and the end of the T wave as measured by electrocardiogram) were\nnot found to be significantly associated with having an LTA. Although powered to detect such associations, we did not find\ncommon genetic variants of large effect associated with having a LTA in those of European descent. This indicates that\ncommon gene variants cannot be used at this time to guide ICD risk-stratification....
Background & Purpose: Rectal toxicity is less common after 125I seed implant brachytherapy for prostate cancer,\r\nand intraoperative rectal dose-volume constraints (the constraint) is still undetermined in pioneering studies. As our\r\nconstraint failed to prevent grade 2 or 3 rectal bleeding (bled-pts) in 5.1% of patients, we retrospectively explored\r\nanother constraint for the prevention of rectal bleeding.\r\nMaterials and methods: The study population consisted of 197 patients treated with the brachytherapy as\r\nmonotherapy using real-time intraoperative transrectal ultrasound (US)-guided treatment at a prescribed dose of 145\r\nGy. Post-implant dosimetry was performed on Day 1 and Day 30 after implantation using computed tomography (CT)\r\nimaging. Rectal bleeding toxicity was classified by CTC-AE ver. 3.0 during a mean 29-month (range, 12-48 months)\r\nperiod after implantation. The differences in rV100s were compared among intraoperative, Day 1 and Day 30 dosimetry,\r\nand between that of patients with grade 2 or 3 rectal bleeding (the bled-pts) and of the others (the spared-pts). All\r\npatients were divided into groups based on provisional rV100s that were increased stepwise in 0.1-cc increments from\r\n0 to 1.0 cc. The difference in the ratios of the bled-pts to the spared-pts was tested by chi-square tests, and their odds\r\nratios were calculated (bled-OR). All statistical analyses were performed by t-tests.\r\nResults: The mean values of rV100us, rV100CT_1, and rV100CT_30 were 0.31 �± 0.43, 0.22 �± 0.36, and 0.59 �± 0.68 cc,\r\nrespectively. These values temporarily decreased (p = 0.020) on Day 1 and increased (p = 0.000) on Day 30. There\r\nwas no significant difference in rV100s between the bled-pts and spared-pts at any time of dosimetry. The\r\nmaximum bled-OR was identified among patients with an rV100us value above 0.1 cc (p = 0.025; OR = 7.8; 95% CI,\r\n1.4-145.8); an rV100CT_1 value above 0.3 cc (p = 0.014; OR = 16.2; 95% CI, 3.9-110.7), and an rV100CT_30 value\r\nabove 0.5 cc (p = 0.019; OR = 6.3; 95% CI, 1.5-42.3).\r\nConclusion: By retrospective analysis exploring rV100 as intraoperative rectal dose-volume thresholds in 125I seed\r\nimplant brachytherapy for prostate cancer, it is proved that rV100 should be less than 0.1 cc for preventing rectal\r\nbleeding....
Objectives. Cost studies can provide useful guidance, so long as they adhere to accepted methodology. Cochlear implants (CIs)\nare electronic devices introduced surgically into the inner ear. It is a relevant example to review cost study analyses because of its\ncostliness. The aim of this study was to review relevant published cost studies of CI to analyze the method used. Methods. First,\nwe described the key points of cost study methodology. Cost studies relating to CI were systematically reviewed, focussing on\nan analysis of the different methods used. Results. The methods, data sources, and estimated cost categories in each study varied\nwidely. The paper showed that cost studies adopted significantly different approaches to estimate costs of CI, reflecting a lack of\nconsensus on the methodology of cost studies. Conclusion. To increase its credibility, closer agreement among researchers on the\nmethodological principles of cost studies would be desirable....
Background: Colorectal-cancer (CRC) research has greatly benefited from the availability of small animal tumor models.\r\nSpontaneous and chemically-induced CRC models are widely used yet limited in their resemblance to human disease and\r\nare often prolonged, not accurately repetitive, and associated with inflammatory side effects. In-situ murine or human\r\ntumor implantation in the gastrointestinal tract of mice is extremely challenging, and limited by inter-animal variability and\r\nprocedure-related complications and mortality. As a result, in frequent studies CRC is implanted in distal sites, most\r\ncommonly the subcutaneous region, an approach that is greatly limited by the absence of normal gastrointestinal tumor\r\nmilieu and has substantial effects on tumor development.\r\nAims: In this study we aimed to develop a well-tolerated repetitive tool to study CRC in small animals by adapting the\r\nmurine colonoscopy system to serve as a platform for colonic sub-mucosal orthotopic implantation of human and murine\r\nCRC tumor cells.\r\nResults: We report the establishment of a novel small-animal CRC model that is minimally invasive, rapid, well-tolerated,\r\nhighly reproducible, and confers precise control of tumor number, location and growth rate. Moreover, we show that this\r\nmodel uniquely allows the side-by-side induction of distinct genetically manipulated tumors, enabling the mechanistic\r\nstudy of tumor interaction and cross-talk within the native intestinal microenvironment.\r\nConclusions: Employment of this new approach may represent a major technical advance for the in-vivo study of CRC....
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