Hypobaric hypotension was used to reduce systemic blood pressure in rats below the lower threshold of CBF autoregulation to evaluate a new laser Doppler (LD) "scanning" technique. Spontaneously breathing male Wistar Kyoto rats (n = 8) were anesthetized with chloral hydrate and the head fixed in a stereotaxic head holder. A cranial window with intact dura mater was introduced to assess local CBF (lCBF) by LD. One stationary probe served to detect rapid flow changes, whereas the second probe was used to sample lCBF recordings from many cortical locations by means of a stepping motor-controlled micromanipulator to obtain lCBF frequency histograms. Advantages are an improved spatial resolution together with the easy detection of low-flow areas and a better comparison of data from individual experiments. Arterial blood pressure was stepwise reduced by exposing the lower body portions to subatmospheric pressures (hypobaric hypotension), thus avoiding the use of drugs or heparinization. The lower threshold of CBF autoregulation was detected by "scanning" at arterial pressures between 50 and 46 mm Hg, with low-flow spots occurring immediately. The data suggest LD scanning as a method suited particularly for studies where lCBF inhomogeneities are expected, e.g., the ischemic penumbra or sinus vein thrombosis.
Background and Purpose-An animal model of incomplete forebrain ischemia resembling human hemodynamic insufficiency was established. The model allows examination of acute and chronic changes of local cerebral blood flow (lCBF) and reserve capacity in correlation with behavioral parameters. Methods-Anesthetized male Wistar-Kyoto rats underwent bilateral carotid occlusion (BCO). Laser-Doppler scanning of lCBF at baseline conditions and after acetazolamide was done 30 minutes after BCO, motor and memory function tests were administered after 1 and 2 days, and both investigations were repeated after 1, 2, 4, and 6 weeks. A sham-operated and a control group without any vessel manipulation served as controls. Results-lCBF dropped within 60 minutes after surgery by 62% (PϽ0.001) in 10 animals surviving BCO (BCO survival ) and by 69% in 5 rats that died within 9 days (BCO lethal ). Acetazolamide increased lCBF to 142.33% in controls, to 136.66% in sham-operated rats (both significant), and to 104.80% in BCO survival (not significant), and it decreased flow by 23.1% in BCO lethal rats (PϽ0.001). Baseline lCBF normalized within 4 weeks. Total motor function scores were significantly reduced from 9 points preoperatively to 5.80Ϯ0.65 in BCO lethal and 6.68Ϯ0.54 points in BCO survival rats 1 day after occlusion. Memory retention function remained impaired after BCO, as did the acetazolamide response, which correlated with motor score and was inversely related to maze exploration time. Conclusions-This model allows long-term follow-up of cerebral function, lCBF, and reserve capacity in a pathophysiological setting similar to hemodynamic insufficiency in humans. (Stroke. 1998;29:2412-2420.)
Cochlear implants (CI) restore functional hearing in the majority of deaf patients. Despite the tremendous success of these devices, some limitations remain. The bottleneck for optimal electrical stimulation with CI is caused by the anatomical gap between the electrode array and the auditory neurons in the inner ear. As a consequence, current devices are limited through 1) low frequency resolution, hence sub-optimal sound quality and 2), large stimulation currents, hence high energy consumption (responsible for significant battery costs and for impeding the development of fully implantable systems). A recently completed, multinational and interdisciplinary project called NANOCI aimed at overcoming current limitations by creating a gapless interface between auditory nerve fibers and the cochlear implant electrode array. This ambitious goal was achieved in vivo by neurotrophin-induced attraction of neurites through an intracochlear gel-nanomatrix onto a modified nanoCI electrode array located in the scala tympani of deafened guinea pigs. Functionally, the gapless interface led to lower stimulation thresholds and a larger dynamic range in vivo, and to reduced stimulation energy requirement (up to fivefold) in an in vitro model using auditory neurons cultured on multi-electrode arrays. In conclusion, the NANOCI project yielded proof of concept that a gapless interface between auditory neurons and cochlear implant electrode arrays is feasible. These findings may be of relevance for the development of future CI systems with better sound quality and performance and lower energy consumption. The present overview/review paper summarizes the NANOCI project history and highlights achievements of the individual work packages.
ObjectivesTumour recurrence of glioblastoma multiforme (GBM) after initial treatment with surgical resection, radiotherapy and chemotherapy is an inevitable phenomenon. This retrospective cohort study compared the efficacy of interstitial high dose rate brachytherapy (HDR-BRT), re-resection and sole dose dense temozolomide chemotherapy (ddTMZ) in the treatment of recurrent glioblastoma after initial surgery and radiochemotherapy.DesignRetropective cohort study.SettingPrimary level of care with two participating centres. The geographical location was central Germany.ParticipantsFrom January 2005 to December 2010, a total of 111 patients developed recurrent GBM after initial surgery and radiotherapy with concomitant temozolomide. The inclusion criteria were as follows: (1) histology-proven diagnosis of primary GBM (WHO grade 4), (2) primary treatment with resection and radiochemotherapy, and (3) tumour recurrence/progression.InterventionsThis study compared retrospectively the efficacy of interstitial HDR-BRT, re-resection and ddTMZ alone in the treatment of recurrent glioblastoma.Primary and secondary outcome measuresMedian survival, progression free survival and complication rate.ResultsMedian survival after salvage therapy of the recurrence was 37, 30 and 26 weeks, respectively. The HDR-BRT group did significantly better than both the reoperation (p<0.05) and the ddTMZ groups (p<0.05). Moderate to severe complications in the HDR-BRT, reoperation and sole chemotherapy groups occurred in 5/50 (10%), 4/36 (11%) and 9/25 (36%) cases, respectively.ConclusionsCT-guided interstitial HDR-BRT attained higher survival benefits in the management of recurrent glioblastoma after initial surgery and radiotherapy with concurrent temozolomide in comparison with the other treatment modalities. The low risk of complications of the HDR-BRT and the fact that it can be delivered percutaneously in local anaesthesia render it a promissing treatment option for selected patients which should be further evaluated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.