Glyphosate (N-(phosphonomethyl)glycine) is the most widely used herbicide on earth. A simple assay to quantify glyphosate concentrations in environmental samples was developed as part of an interdisciplinary effort linking introductory laboratory courses in chemistry, biology, and microbiology. In this 3 h laboratory experiment, students used UV−vis spectroscopy to quantify glyphosate in prepared unknowns and supernatants from glyphosate-treated soil samples. Regression analysis indicated that the assay is linear up to 20.0 ppm, making it particularly useful for detection of low levels of glyphosate in environmental samples. The assay can be used to quantify the activity of glyphosate-degrading soil microorganisms by comparing glyphosate levels between autoclaved and nonautoclaved soil slurries.
To evaluate the prophylactic effect of intravitreal pegaptanib sodium on choroidal neovascularization membrane (CNVM) development and compare its performance with that of triamcinolone acetonide. Methods: In drug-treated and control groups, CNVMs were induced by laser trauma. Immediately after undergoing the laser procedure, animals received intravitreal injections of pegaptanib sodium, 8 or 17 µg; triamcinolone acetonide, 200 µg; or a vehicle solution. After 21 days, fluorescein angiography was performed. The CNVM mean diameters and radial thicknesses were measured histologically. Results: Mean CNVM diameters were 10% to 13% smaller in pegaptanib-treated eyes and 43% smaller in triamcinolone-treated eyes compared with laser-only control eyes. Late-stage fluorescein angiography leakage scores, on a scale of 0 to 3, suggested a statistical difference between triamcinolone-(0.6) and pegaptanib 8 µg-treated (1.5) groups compared with the laser-only control group (2.0). The CNVM mean thicknesses were greater in the pegaptanib 8 µg-(79 µm) and pegaptanib 17 µg-treated (71 µm) groups and significantly smaller in the triamcinolonetreated group (26 µm) compared with the laser-only control group (67 µm). Conclusion: In this animal model of choroidal neovascularization, intravitreal pegaptanib exhibited marginal or no effect on CNVM development; whereas intravitreal triamcinolone evoked robust inhibition of CNVMs. Clinical Relevance: Pegaptanib treatment may be insufficient to prevent CNVM formation.
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