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Cross-polarized reflected light measurement of fast optical responses associated with neural activation 下载免费PDF全文
We developed an optical probe for cross-polarized reflected light measurements and investigated optical signals associated with electrophysiological activation in isolated lobster nerves. The cross-polarized baseline light intensity (structural signal) and the amplitude of the transient response to stimulation (functional signal) measured in reflected mode were dependent on the orientation of the nerve axis relative to the polarization plane of incident light. The maximum structural signal and functional response amplitude were observed at 45 degrees , and the ratio of functional to structural signals was approximately constant across orientations. Functional responses were measured in single trials in both transmitted and reflected geometries and responses had similar waveforms. Both structural and functional signals were an order of magnitude smaller in reflected than in transmitted light measurements, but functional responses had similar signal/noise ratios. We propose a theoretical model based on geometrical optics that is consistent with experimental results. In the model, the cross-polarized structural signal results from light reflection from axonal fibers and the transient functional response arises from axonal swelling associated with neural activation. Polarization-sensitive reflected light measurements could greatly enhance in vivo imaging of neural activation since cross-polarized responses are much larger than scattering signals now employed for dynamic functional neuroimaging. 相似文献
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Chloe?KB?Mortimer Tansy?M?Peters Saheer?E?Gharbia Julie?MJ?Logan Catherine?ArnoldEmail author 《BMC microbiology》2004,4(1):31
Background
The fliC and fljB genes in Salmonella code for the phase 1 (H1) and phase 2 (H2) flagellin respectively, the rfb cluster encodes the majority of enzymes for polysaccharide (O) antigen biosynthesis, together they determine the antigenic profile by which Salmonella are identified. Sequencing and characterisation of fliC was performed in the development of a molecular serotyping technique. 相似文献16.
Anna B. Cope Kimberly A. Powers JoAnn D. Kuruc Peter A. Leone Jeffrey A. Anderson Li-Hua Ping Laura P. Kincer Ronald Swanstrom Victoria L. Mobley Evelyn Foust Cynthia L. Gay Joseph J. Eron Myron S. Cohen William C. Miller 《PloS one》2015,10(6)
Objective
HIV transmission is influenced by status awareness and receipt of care and treatment. We analyzed these attributes of named partners of persons with acute HIV infection (index AHI cases) to characterize the transmission landscape in North Carolina (NC).Design
Secondary analysis of programmatic data.Methods
We used data from the NC Screening and Tracing of Active Transmission Program (2002–2013) to determine HIV status (uninfected, AHI, or chronic HIV infection [CHI]), diagnosis status (new or previously-diagnosed), and care and treatment status (not in care, in care and not on treatment, in care and on treatment) of index AHI cases'' named partners. We developed an algorithm identifying the most likely transmission source among known HIV-infected partners to estimate the proportion of transmissions arising from contact with persons at different HIV continuum stages. We conducted a complementary analysis among a subset of index AHI cases and partners with phylogenetically-linked viruses.Results
Overall, 358 index AHI cases named 932 partners, of which 218 were found to be HIV-infected (162 (74.3%) previously-diagnosed, 11 (5.0%) new AHI, 45 (20.6%) new CHI). Most transmission events appeared attributable to previously-diagnosed partners (77.4%, 95% confidence interval 69.4–85.3%). Among these previously-diagnosed partners, 23.2% (14.0–32.3%) were reported as in care and on treatment near the index AHI case diagnosis date. In the subset study of 33 phylogenetically-linked cases and partners, 60.6% of partners were previously diagnosed (43.9–77.3%).Conclusions
A substantial proportion of HIV transmission in this setting appears attributable to contact with previously-diagnosed partners, reinforcing the need for improved engagement in care after diagnosis. 相似文献17.
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Haidet-Phillips AM Hester ME Miranda CJ Meyer K Braun L Frakes A Song S Likhite S Murtha MJ Foust KD Rao M Eagle A Kammesheidt A Christensen A Mendell JR Burghes AH Kaspar BK 《Nature biotechnology》2011,29(9):824-828
Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease, with astrocytes implicated as contributing substantially to motor neuron death in familial (F)ALS. However, the proposed role of astrocytes in the pathology of ALS derives in part from rodent models of FALS based upon dominant mutations within the superoxide dismutase 1 (SOD1) gene, which account for <2% of all ALS cases. Their role in sporadic (S)ALS, which affects >90% of ALS patients, remains to be established. Using astrocytes generated from postmortem tissue from both FALS and SALS patients, we show that astrocytes derived from both patient groups are similarly toxic to motor neurons. We also demonstrate that SOD1 is a viable target for SALS, as its knockdown significantly attenuates astrocyte-mediated toxicity toward motor neurons. Our data highlight astrocytes as a non-cell autonomous component in SALS and provide an in vitro model system to investigate common disease mechanisms and evaluate potential therapies for SALS and FALS. 相似文献
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Sara E. Gombash Lampe Brian K. Kaspar Kevin D. Foust 《Journal of visualized experiments : JoVE》2014,(93)
Intravenous injection is a clinically applicable manner to deliver therapeutics. For adult rodents and larger animals, intravenous injections are technically feasible and routine. However, some mouse models can have early onset of disease with a rapid progression that makes administration of potential therapies difficult. The temporal (or facial) vein is just anterior to the ear bud in mice and is clearly visible for the first two days after birth on either side of the head using a dissecting microscope. During this window, the temporal vein can be injected with volumes up to 50 μl. The injection is safe and well tolerated by both the pups and the dams. A typical injection procedure is completed within 1-2 min, after which the pup is returned to the home cage. By the third postnatal day the vein is difficult to visualize and the injection procedure becomes technically unreliable. This technique has been used for delivery of adeno-associated virus (AAV) vectors, which in turn can provide almost body-wide, stable transgene expression for the life of the animal depending on the viral serotype chosen. 相似文献
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Patrick Royston Friederike M-S Barthel Mahesh KB Parmar Babak Choodari-Oskooei Valerie Isham 《Trials》2011,12(1):1-18