The Science and Art of Nerve Fiber Teasing for Myelinated Nerves: Methodology and Interpretation

Nerve fiber teasing is a sensitive technique utilized in diagnostic neuropathology practice, laboratory research, and animal toxicity studies for characterizing changes in single myelinated nerve fibers over extended distances. In animal toxicity studies, a nerve portion (approximately 10 mm in length) is stained with Sudan black for 24 to 48 hours and then transferred into a drop of viscous medium (eg, glycerin) mounted on an adhesive-coated glass slide, positioning it such that the proximodistal orientation is known. Individual fibers are removed using fine forceps while the sample is viewed under a stereomicroscope. In general, lesions can be identified during teasing, but more detailed characterization and photodocumentation is undertaken once nerve fibers have been dried and coverslipped. Nerve fiber teasing is particularly useful for distinguishing early stages of axonal degeneration (which presents as ovoid fiber fragments in the midinternodal region) from segmental demyelination (which presents as loss of original myelin segments and their replacement by thinner, shorter segments in the absence of axonal damage). The slow, laborious nature of nerve fiber teasing dictates that the technique will be employed on a few samples as an auxiliary method to better define the pathogenesis of nerve lesions first identified by conventional histopathologic assessment.

A colorimetric method for the sequence-specific recognition of double-stranded DNA on the surface of a silver-coated glass slide

In this study, a colorimetric method for sequence-specific recognition of double-stranded DNA (dsDNA) was established on the surface of a silver-coated glass slide. Oligo-1 was assembled on the surface of a silver-coated glass slide through an Ag–S bond, and Oligo-2 as reporter was used to bind with streptavidin-horseradish peroxidase (SA–HRP). They could bind with target dsDNA that was composed of Oligo-3 and Oligo-4 on the surface of a silver-coated glass slide through triplex formation. The bound HRP could be moved into the solution by DNase I and catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB). Therefore, the concentration of target dsDNA could be determined with the colour change of TMB. Under the optimum conditions, the absorbance was proportional to the concentration of target dsDNA over the range of 100 pmol/L to 2.0 nmol/L, with a detection limit of 13 pmol/L. In addition, this method showed good sequence selectivity, enabling it to be further developed for the detection of other polymerase chain reaction (PCR) products.

Localized surface plasmon resonance sensing properties of photocatalytically prepared Ag/TiO2 films

Photocatalytic deposition of Ag nanoparticles from a mixed aqueous solution of AgNO3 and polyvinylpyrrolidone (PVP) onto TiO2 film supported on indium-tin oxide-coated glass slide (Ag/TiO2 film) was carried out by using UV light irradiation. The size and shape of the Ag nanoparticles were controlled by the addition of PVP during the photodeposition. In the optical absorption spectra of the Ag/TiO2 film, the localized surface plasmon resonance (LSPR) absorption of the Ag nanoparticles was observed. When the film was immersed in various kinds of alcohols with the refractive index at 20°C (), ranging between 1.3292 and 1.4103, the peak LSPR absorption was shifted to longer wavelengths and the peak absorbance increased with increasing . The spectral change of the Ag/TiO2 film with larger spherical Ag nanoparticles was more prominent than that with smaller ones.