Effects of epidural compression on stellate neurons and thalamocortical afferent fibers in the rat primary somatosensory cortex

A number of neurological disorders such as epidural hematoma can cause compression of cerebral cortex. We here tested the hypothesis that sustained compression of primary somatosensory cortex may affect stellate neurons and thalamocortical afferent (TCA) fibers. A rat model with barrel cortex subjected to bead epidural compression was used. Golgi‑Cox staining analyses showed the shrinkage of dendritic arbors and the stripping of dendritic spines of stellate neurons for at least 3 months post‑lesion. Anterograde tracing analyses exhibited a progressive decline of TCA fiber density in barrel field for 6 months post‑lesion. Due to the abrupt decrease of TCA fiber density at 3 days after compression, we further used electron microscopy to investigate the ultrastructure of TCA fibers at this time. Some TCA fiber terminal profiles with dissolved or darkened mitochondria and fewer synaptic vesicles were distorted and broken. Furthermore, the disruption of mitochondria and myelin sheath was observed in some myelinated TCA fibers. In addition, expressions of oxidative markers 3‑nitrotyrosine and 4‑hydroxynonenal were elevated in barrel field post‑lesion. Treatment of antioxidant ascorbic acid or apocynin was able to reverse the increase of oxidative stress and the decline of TCA fiber density, rather than the shrinkage of dendrites and the stripping of dendritic spines of stellate neurons post‑lesion. Together, these results indicate that sustained epidural compression of primary somatosensory cortex affects the TCA fibers and the dendrites of stellate neurons for a prolonged period. In addition, oxidative stress is responsible for the reduction of TCA fiber density in barrels rather than the shrinkage of dendrites and the stripping of dendritic spines of stellate neurons

Temperature effects of Mach-Zehnder interferometer using a liquid crystal-filled fiber

We demonstrated a simple and cost-effective method to fabricate all fiber Mach-Zehnder interferometer (MZI) based on cascading a short section of liquid crystal (LC)-filled hollow-optic fiber (HOF) between two single mode fibers by using automatically splicing technique. The transmission spectra of the proposed MZI with different LC-infiltrated length were measured and the temperature-induced wavelength shifts of the interference fringes were recorded. Both blue shift and red shift were observed, depending the temperature range. Based on our experimental results, interference fringe was observed with a maximum interferometric contrast over 35dB. The temperature-induced resonant wavelength blue-shifts 70.4 nm for the MZI with an LC length of 9.79 mm and the wavelength temperature sensitivity of -1.55 nm/°C is easily achieved as the temperature increases from 25°C to 77°C

Analysis of Resistance to Clarithromycin and Virulence Markers in Helicobacter pylori Clinical Isolates from Eastern Taiwan

AbstractObjectiveLittle information is available concerning the relationships between clarithromycin resistance and virulence marker genes (iceA, cagA and vacA) in Helicobacter pylori isolated in Taiwan. The aim of this study was to evaluate the possible association between clarithromycin resistance and genotypes of the virulence markers on clarithromycin-resistant H. pylori isolates obtained in eastern TaiwanMaterials and MethodsThe genotypes of the virulence marker genes (iceA, cagA and vacA) were analyzed by PCR, and the 23S rDNA region from 18 clarithromycin-resistant clinical isolates of H. pylori was amplified by PCR and sequenced.ResultsPoint mutations were found to occur in all isolates. Two isolates had A2143G, six had T2182C, one had C2227T, six had A2143G plus T2182C, and three had heterozygous alleles. The latter included a wild-type allele (A2143) plus (i) an A2143G, (ii) an A2143G plus an A2223G, and (iii) an A2143G plus a T2182C. The prevalence of the marker genes cagA, iceA1, iceA2, and both iceA1 and iceA2, in the isolates was 95.5%, 66.9%, 7.5%, and 25.6%, respectively. The vacAs1 allele was detected in all isolates, whereas the m1 and m2 alleles were found in 44.4% and 55.6% of the isolates, respectivelyConclusionThere were no significant associations between clarithromycin resistance and the presence of the cagA gene, vacA allele mosaicism, and the iceA genotypes. The most notable finding of our study was that the C2227T single mutation in 23S rDNA could also be related to the high clarithromycin minimal inhibitory concentrations in clinical isolates from eastern Taiwan

Widely Tunable Picosecond-Pulsed Source near 2 μm based on Cascaded Raman Wavelength Shifting

We demonstrate a cavity-less picosecond pulsed source near 2μm, tunable over more than 200nm based on third order cascaded Raman wavelength shifting. Up to 44% conversion is achieved for 100mW peak powers at 200MHz repetition rate

Thulium Assisted Parametric Conversion from Near to Short Wave Infrared

We report an all-fiber continuous wave source, tunable between 1935-1980nm, based on parametric conversion combined with thulium amplification. More than 150mW of power and 30dB optical signal-to-noise ratio is obtained over the entire range. OCIS codes: (190.4975) Parametric processes, (230.2285) Fiber devices and optical amplifiers, (060.4370) Nonlinear optics, fibers

Tunable Thulium-Assisted Parametric Generation of 10 Gb/s Intensity Modulated Signals Near 2 μm

We report the demonstration of an all-fiber 10Gb/s modulation capable source near 2μm, tunable over more than 60nm with powers exceeding 2dBm, based on parametric conversion and appended Thulium amplification

A Potential Antifungal Effect of Chitosan Against Candida albicans Is Mediated via the Inhibition of SAGA Complex Component Expression and the Subsequent Alteration of Cell Surface Integrity

Due to the high incidence of nosocomial Candida albicans infection, the first-line drugs for C. albicans infection have been heavily used, and the emergence of drug-resistant strains has gradually increased. Thus, a new antifungal drug or therapeutic method is needed. Chitosan, a product of chitin deacetylation, is considered to be potentially therapeutic for fungal infections because of its excellent biocompatibility, biodegradability and low toxicity. The biocidal action of chitosan against C. albicans shows great commercial potential, but the exact mechanisms underlying its antimicrobial activity are unclear. To reveal these mechanisms, mutant library screening was performed. ADA2 gene, which encodes a histone acetylation coactivator in the SAGA complex, was identified. Transmission electronic microscopy images showed that the surface of chitosan-treated ada2Δ cells was substantially disrupted and displayed an irregular morphology. Interestingly, the cell wall of ada2Δ cells was significantly thinner than that of wild-type cells, with a thickness similar to that seen in the chitosan-treated wild-type strain. Although ADA2 is required for chitosan tolerance, expression of ADA2 and several Ada2-mediated cell wall-related genes (ALS2, PGA45, and ACE2) and efflux transporter genes (MDR1 and CDR1) were significantly inhibited by chitosan. Furthermore, GCN5 encoding a SAGA complex catalytic subunit was inhibited by chitosan, and gcn5Δ cells exhibited phenotypes comparable to those of ada2Δ cells in response to chitosan and other cell surface-disrupting agents. This study demonstrated that a potential antifungal mechanism of chitosan against C. albicans operates by inhibiting SAGA complex gene expression, which decreases the protection of the cell surface against chitosan