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At least 883 records · Page 49Linked to original sources
PubMed1992

Muscle oxygenation by fast near infrared spectrophotometry (NIRS) in ischemic forearm.

Fast scanning near infrared spectroscopy (680-1050nm) was utilized to evaluate human forearm muscle oxygenation in 15 adults volunteers. Spectra were recorded in hypoxic hypoxia, ischemia and venous outflow restriction. Derivative spectra were performed with the aim to obtain a quantitative information of Hb/Mb oxygen saturation free from volume and scattering changes. The absorption spectra O.D. demonstrate an increase of deoxy-Hb/Mb in hypoxic condition with a moderate volume changes. In ischemia a rapid Hb/Mb desaturation occurred until a plateau was reached at 4th min. The cuff release was followed by hyperemia with Hb volume raise and oxy-Hb/Mb increase above the control. Spectral data support the hypothesis that derivative NIRS can be used to identify muscle oxygenation changes.

Adult↗
PubMed1992

Quantitation of tissue optical characteristics and hemoglobin desaturation by time- and frequency-resolved multi-wavelength spectrophotometry.

Photon migration in highly scattering tissues such as muscle and brain gives optical pathlengths that are dependent upon absorption and scattering parameters, mu a, mu s'. Determination of these parameters gives the correct concentration of principal absorber such as hemoglobin in the red region of the spectrum. Determinations of scatter factor in functioning and pathological tissues are made.

Alzheimer Disease↗
PubMed1989

Near infrared quadruple wavelength spectrophotometry of the rat head.

A quadruple wavelength method to monitor the changes in concentration of oxygenated and deoxygenated hemoglobin and the redox state of cytochrome oxidase within a living tissue is presented. The expected advantages of this technique over the triple wavelength method are (i) that it can compensate for the light scattering change of tissue itself or for instabilities of light source and photomultiplier, (ii) that it can treat the optical properties of the red blood cell in a tissue in the same way as in an in vitro model system, and (iii) that it requires no estimation of the absorption coefficient of cytochrome oxidase in situ.

Animals↗
PubMed1986

Two-dimensional spectrophotometry and pseudo-color representation of chemical reaction patterns.

The formation of spatio-temporal patterns in layers of chemical and biochemical media is observed and quantified by a two-dimensional spectrophotometer based on a computerized video equipment with high spatial, temporal, and intensity resolution. Images are shown, to some extent, in pseudo-colors. The use of pseudo-colors and three-dimensional perspective representations enhances the perception of the information contained in an image and the inherent order of the spatial structures.

Chemical Phenomena↗
PubMed1980

The rate of calcium extraction during EDTA decalcification from thin bone slices as assessed with atomic absorption spectrophotometry.

The rate of calcium extraction with EDTA (ethylenediamine tetraacetic acid) from thin bone slices (300 micrometer-3 mm thick) was determined by aid of an atomic absorption spectrophotometer. A 0.5 mm thick bone slice was completely decalcified with 15% (0.40 M), 8% (0.22 M), and 4% (0.11 M) EDTA in 24 h, 3 days, and 5 days, respectively (vol. 15 ml, temp. 4 degrees C, pH 7.4). At 37 and 60 degrees C the speed of demineralization was slightly increased as compared with that at 20 degrees C, while no difference was observed between 4 and 20 degrees C. Bone slices with a thickness of 0.3, 0.5, 1 and 2 mm were decalcified -- in the same order -- in 24 h, 2, 3, and 5 days (8% EDTA, 4 degrees C, pH 7.4). At pH 7.4, the decalcification rate was a little slower than at pH 5.0 and 8.5. Agitation did not affect the decalcifying velocity, nor did the volume of the agent, except when the volume was very small. The demineralization of ordinary bone, containing both compact and spongy bone, was found to be more rapid than that of homogeneous bone reported earlier. The acidic buffers and New Decalc, which served as reference substances, exerted a more vigorous decalcifying effect thatn EDTA. K formate/formic acid buffer, pH 3.15, demineralized a 1 mm thick bone slice in 24 h and 2 days was needed with Na lactate/lactic acid buffer, pH 3.70. With New Decalc, pH 0.9, the corresponding demineralization was accomplished in 1.5 h. Atomic absorption spectrophotometer proved to be a useful tool in the evaluation of calcium extraction velocity from bone slices.

Animals↗