Search results for "Spectroscopy"
showing 10 items of 10293 documents
Glutathione conjugation of trans-3,4-dihydroxy 1,2-epoxy l,2,3,4-tetrahydrobenzo[c]phenanthrene isomers by human glutathione transferases
1992
Each of the four stereoisomers of trans-3,4-dihydroxy 1,2-epoxy 1,2,3,4-tetrahydrobenzo[c]phenanthrene [(+)- and (-)-anti-BPhDE and (+)- and (-)-syn-BPhDE] has been incubated with the human glutathione transferase (GST) isoenzymes GST A1-1, GST M1-1 and GST P1-1, representing class alpha, mu and pi respectively, and glutathione (GSH). The conjugates formed were analyzed by HPLC and the results demonstrate that all GST isoenzymes catalyze the formation of GSH conjugates of all BPhDE isomers. However, a marked variation in catalytic efficiencies was observed (0.122-1.28/mM/s). These values are considerably lower than those previously estimated for the bay-region diol epoxides of benzo[a]pyren…
Metabolic aggressiveness in benign meningiomas with chromosomal instabilities.
2010
Abstract Meningiomas are often considered benign tumors curable by surgery, but most recurrent meningiomas correspond to histologic benign tumors. Because alterations in chromosome 14 among others have suggested clinical aggressiveness and recurrence, determining both the molecular phenotype and the genetic profile may help distinguish tumors with aggressive metabolism. The aim of this study was to achieve higher specificity in the detection of meningioma subgroups by measuring chromosomal instabilities by fluorescence in situ hybridization and cytogenetics and metabolic phenotypes by high-resolution magic angle spinning spectroscopy. We studied 46 meningioma biopsies with these methodologi…
Optimization of a GF-AAS method for lead testing in blood and urine: A useful tool in acute abdominal pain management in emergency.
2021
Suspicion of lead poisoning is confirmed by its concentration in blood and protoporphyrin red blood cells. At low concentrations, lead influences the synthesis of the heme in the sense of lowering it. Acute and chronic lead intoxication is extremely polymorphic in regards to its clinical manifestations, with digestive, hematological, cardiovascular, renal hepatic and neurological features. The aim of the study was to evaluate the presence of lead in human whole blood and urine harvested before and during chelation treatment in the case of lead poisoning. An atomic absorption spectroscopic method for the analysis of lead was developed using graphite furnace atomic absorption spectrophotomete…
WIN55,212-2-induced expression of Mir-29b1 favours the suppression of osteosarcoma cell migration in a SPARC-independent manner
2019
WIN55,212-2 (WIN) is a synthetic agonist of cannabinoid receptors that displays promising antitumour properties. The aim of this study is to demonstrate that WIN is able to block the migratory ability of osteosarcoma cells and characterize the mechanisms involved. Using wound healing assay and zymography, we showed that WIN affects cell migration and reduces the activity of the metalloproteases MMP2 and MMP9. This effect seemed to be independent of secreted protein acidic and rich in cysteine (SPARC), a matricellular protein involved in tissue remodeling and extracellular matrix deposition. SPARC release was indeed prevented by WIN, and SPARC silencing by RNA interference did not influence …
Quantitative global mapping of terrestrial vegetation photosynthesis
2017
Although traditional remote sensing systems based on spectral reflectance can already provide estimates of the 'potential' photosynthetic activity of terrestrial vegetation through the quantification of total canopy chlorophyll content or absorbed photosynthetic radiation, the determination of the 'actual' photosynthetic activity of terrestrial vegetation requires information about how the absorbed light is used by plants, such as vegetation fluorescence, using very high spectral resolution spectroscopy in the range 650-800 nm. The Fluorescence Explorer (FLEX) mission, selected in November 2015 as the 8th Earth Explorer by the European Space Agency (ESA), carries the FLORIS spectrometer, wi…
Evaluating the predictive power of sun-induced chlorophyll fluorescence to estimate net photosynthesis of vegetation canopies: A SCOPE modeling study
2016
Abstract Progress in imaging spectroscopy technology and data processing can enable derivation of the complete sun-induced chlorophyll fluorescence (SIF) emission spectrum. This opens up opportunities to fully exploit the use of the SIF spectrum as an indicator of photosynthetic activity. Simulations performed with the coupled fluorescence–photosynthesis model SCOPE were used to determine how strongly canopy-leaving SIF can be related to net photosynthesis of the canopy (NPC) for various canopy configurations. Regression analysis between SIF retrievals and NPC values produced the following general findings: (1) individual SIF bands that were most sensitive to NPC were located around the fir…
Variability and Uncertainty Challenges in Scaling Imaging Spectroscopy Retrievals and Validations from Leaves Up to Vegetation Canopies
2019
Imaging spectroscopy of vegetation requires methods for scaling and generalizing optical signals that are reflected, transmitted and emitted in the solar wavelength domain from single leaves and observed at the level of canopies by proximal sensing, airborne and satellite spectroradiometers. The upscaling embedded in imaging spectroscopy retrievals and validations of plant biochemical and structural traits is challenged by natural variability and measurement uncertainties. Sources of the leaf-to-canopy upscaling variability and uncertainties are reviewed with respect to: (1) implementation of retrieval algorithms and (2) their parameterization and validation of quantitative products through…
An integrated approach for high spatial resolution mapping of water and carbon fluxes using multi-sensor satellite data
2012
In the last years, modeling of surface processes - such as water, energy and carbon budgets, as well as vegetation growth- seems to be focused on integrated approaches that combine aspects of hydrology, biology and meteorology into unified analyses. In this context, remotely sensed data often have a core role due to the cross-cutting impact of this novel source of spatially distributed information on all these research areas. However, several applications - such as drought monitoring, yield forecasting and crop management - require spatially detailed products at sub-field scales, which can be obtained only with support of adequately fine resolution remote sensing data (< 100 m). In particul…
The scattering and re-absorption of red and near-infrared chlorophyll fluorescence in the models Fluspect and SCOPE
2019
Scattering and re-absorption have been recognized as relevant aspects for the interpretation of solar induced chlorophyll fluorescence (SIF) in vegetation remote sensing. In an earlier study [Yang and Van der Tol, RSE 215, 97–108, 2018] we addressed the problem of scattering and re-absorption of near-infrared fluorescence in the vegetation canopy. In this study we analyse within-leaf re-absorption of both red and near-infrared fluorescence using the radiative transfer model Fluspect. The leaf scattering determines the ratio of backward to total leaf fluorescence emission Fb/(Fb + Ff). Fluspect reproduces this ratio with an RMSE of less than 0.1, and explains the observed dependence of the s…
Remote sensing of sunlight-induced chlorophyll fluorescence and reflectance of Scots pine in the boreal forest during spring recovery
2005
A measurement campaign to assess the feasibility of remote sensing of sunlight-induced chlorophyll fluorescence (ChlF) from a coniferous canopy was conducted in a boreal forest study site (Finland). A Passive Multi-wavelength Fluorescence Detector (PMFD) sensor, developed in the LURE laboratory, was used to obtain simultaneous measurements of ChlF in the oxygen absorption bands, at 687 and 760 nm, and a reflectance index, the PRI (Physiological Reflectance Index), for a month during spring recovery. When these data were compared with active fluorescence measurements performed on needles they revealed the same trend. During sunny days fluorescence and reflectance signals were found to be str…