Near-infrared Spectrophotometry Research Articles

Detection of dynamic changes in cerebral oxygenation coupled to neuronal function during mental work in man

Changes in the oxygenation state of brain hemoglobin during mental work were monitored in real time (time resolution: 1 s) using near-infrared spectrophotometry in 14 healthy volunteers. In a younger group (age range 22–30 years, n = 12), the subjects finding difficulty in solving a problem were accompanied by significant increases in both oxygenated hemoglobin and total hemoglobin, while the subjects making a correct answer without difficulty showed no significant changes in hemoglobin oxygenation. When compared with those younger subjects, observations on the older subject demonstrated a decrease in oxygenated hemoglobin and a reciprocal increase in deoxygenated hemoglobin, unaccompanied by changes in total hemoglobin.

Gender- and handedness-related differences of forebrain oxygenation and hemodynamics

To elucidate gender- and handedness-related differences between the hemispheres of the brain in their metabolisms and hemodynamics, simultaneous monitoring by near-infrared (NIR) spectrophotometry of hemoglobin (Hb) in both hemispheres of the forebrain during the mirror drawing task (MDT) was performed. Bilaterally simultaneous increases of oxygenated Hb and decreases of deoxygenated Hb in forebrain occurred symmetrically in all cases of volunteer subjects except for two. There were gender- and handedness-related differences of hemodynamics between the hemispheres of the brain; NIR results showed that a large majority of women used both sides of the brain when concentrating on carrying out the MDT, whilst most men, especially left-handers, reacted mainly using the hemisphere which was 'dominant' according to handedness.

Near-infrared spectrophotometry of FU Orionis variables

Water vapor absorption features were detected at 1.4 and 1.9 μm in all the six observed objects; four FU Orionis variables (FU Ori, V1515 Cyg, V1057 Cyg, and Elias 1-12) and two related objects (L1551 IRS 5 and Z CMa). The idea that the water vapor appears by vaporization of ice or crystalline water in the grains or rocks accreting from the outer and cooler regions of a disk surrounding T Tauri stars, in conjunction with the flare-up of the FU Orionis variables, is discussed

Near-Infrared Spectrophotometry: A New Dimension in Clinical Chemistry

The near-infrared (NIR) spectral region (700-2500 nm) is a fertile source of chemical information in the form of overtone and combination bands of the fundamental infrared absorptions and low-energy electronic transitions. This region was initially perceived as being too complex for interpretation and consequently was poorly utilized. Advances in chemometric techniques that can extract massive amounts of chemical information from the highly overlapped, complex spectra have led to extensive use of NIR spectrophotometry (NIRS) in the food, agriculture, pharmaceutical, chemical, and polymer industries. The application of NIRS in clinical laboratory measurements is still in its infancy. NIRS is a simple, quick, nondestructive technique capable of providing clinically relevant analyses of biological samples with precision and accuracy comparable with the method used to derive the NIRS models. Analyses can be performed with little or no sample preparation and no reagents. The success of NIRS in any particular case is determined by the complexity of the sample matrix, relative NIR absorptivities of the constituents, and the wavelengths and regression technique chosen. We describe the general approach to data acquisition, calibration, and analysis, using serum proteins, triglycerides, and glucose as examples.

Simultaneous visible and near-infrared spectrophotometry of Comet Austin 1989c

Simultaneous visible and near-infrared spectra of Comet Austin were obtained wit the 1.5 m and 2.3 m telescopes of the University of Arizona Observatories on 1990 May 16. The visible spectrum obtained with the IHW spectrograph covers the 3126-9490 A wavelength interval, while the near-infrared spectrum obtained with the germanium spectrometer covers the 9036-12794 A wavelength interval. Simultaneous measurements of integrated band fluxes are presented for the CN B 2Sigma(+) - X 2Sigma(+) (violet) and A 2Pi - X 2Sigma(+) (red) systems. A CN spectrum and CN band flux ratios calculated from a fluoresence equilibrium model are also presented. From a comparison between the observed and calculated CN spectra and band flux ratios, it is found that red system oscillator strengths determined from recent ab initio calculations appropriately describe the radiative properties of CN molecules.

Cellulase Solution Concentrations Used to Develop Spectral Equations for Predicting Tall Fescue Digestibility

AbstractDigestibility estimates obtained with prepared cellulase solutions and near infrared spectrophotometry (NIRS) have become valuable and reliable tools for forage quality determination. The objective of this study was to determine the optimum concentration of a prepared cellulase solution from a commercial source to obtain meaningful estimates of in vitro dry matter digestibility (IVDMD) and development of NIRS equations for tall fescue (Festuca arundinacea Schreb.). A total of 176 tall fescue samples were pretreated using pepsin and 0.125 M L−1 HCI followed by digestion using five different concentrations of a prepared cellulase solution obtained from Worthington Corp., Freehold, NJ. Concentrations of the prepared cellulase solution were 0.0, 0.2, 0.4, 0.6, and 0.8 g L−1. Maximum digestion occurred with the prepared cellulase solution at 0.57 g L−1. However, the most meaningful equation for estimating tall fescue IVDMD by NIRS occurred when samples were digested using the prepared cellulase solution at a concentration of 0.8 g L−1.

Noninvasive methods for estimating in vivo oxygenation.

Clinical signs of hypoxia and hyperoxia are nonspecific and unreliable, yet both are potentially injurious. Noninvasive methods of oxygen assessment fill the gap between clinical observation and invasive tests, helping physicians deliver sufficient oxygen with minimum toxicity. Potential sites for oxygen measurement vary between the blood and the mitochondria; each method measures at a different site and detects different types of hypoxia and hyperoxia. Thus, values obtained by two different methods are not equivalent, giving each method unique strengths and weaknesses. We review two clinical methods (pulse oximetry and transcutaneous oximetry), as well as four experimental methods (near-infrared spectrophotometry, magnetic resonance spectroscopy, magnetic resonance saturation imaging, and time-of-flight absorbance spectrophotometry). The principles of each method and the clinical situations in which each succeeds or fails are discussed. A fundamental understanding of each method can help in deciding which methods, if any, are appropriate for a given patient and how best to correct observed oxygenation problems once they are discovered.

Evaluation of the algorithm used in near infrared spectrophotometry.

The major causes of death and disability in a neonatal intensive care unit (NICU) are cerebral ischemia and intra-ventricular hemorrhage. The monitoring of cerebral oxygenation and hemodynamics is of utmost importance for the care of the preterm infant. A small, inexpensive and continuous measuring bedside instrument is a substantial extension of the NICU. The technique of near infrared spectrophotometry (NIRS) might provide in this need.

Cerebral oxygenation state in chemically-induced seizures in the rat--study by near infrared spectrophotometry.

The hemoglobin oxygenation state and the redox state of Cyt.ox. in the rat brain during and after seizure induced by PTZ were measured by using near-infrared spectrophotometry. PTZ administration caused transient reduction of Cyt.ox. in the brain, which might be a trigger for the increase of CBF during seizure. In postictal phase, although BP remained high, Cyt.ox. was in the certain reduced state, which might be due to A-V shunt. Hypoxic loading during seizure caused more reduction of Cyt.ox. than under non-epileptic conditions, which meant that seizure even under mild hypoxic conditions could cause severe hypoxic brain damage.

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.

Brain oxygenation state: preparation of isolated perfused rat brain and near-infrared spectrophotometry.

The method of blood-free isolated perfused rat brain was described, of which EEG was within the normal range. The simultaneous measurement of heme a+a3 and copper in cytochrome oxidase could be performed under the various conditions such as graded hypoxia and seizure. The relationship between these two chromophores in the brain was same to that of isolated mitochondria.

Noninvasive Monitoring of Tissue Oxygenation by Near-infrared Spectrophotometry

Noninvasive Monitoring of Tissue Oxygenation by Near-infrared Spectrophotometry

Rapid reduction of intestinal cytochrome a, a3 during lethal endotoxemia

In vivo near-infrared spectrophotometry was used to determine whether lethal endotoxemia impairs small intestinal oxidative phosphorylation as reflected by the redox state of mitochondrial cytochrome a, a 3 (AA3). Adult male Sprague-Dawley rats were anesthetized with 2.1% isoflurane in 30% O 2:70% N 2O, and the small intestine was partially exteriorized for spectrophotometric monitoring (OMNI-3). By 5 min after an iv bolus of Escherichia coli endotoxin (40 mg/kg, LD 90, n = 7) a significant shift toward reduction in intestinal AA3 had occurred in association with hypotension and a marked fall in both superior mesenteric artery blood flow (SMAF) and cardiac output. In a separate group ( n = 7) SMAF was kept at the baseline level by periodic infusions of donor rat plasma begun 1 min after endotoxin injection, and the reduction in AA3 was again found despite the fluid loading intervention which successfully maintained not only organ blood flow, but also cardiac output and mean arterial pressure in their normal ranges. Further experiments ( n = 34) measuring SM vascular bed oxygen consumption indicated that intestinal VO 2 remained unchanged during early endotoxemia. These findings suggest a rapid impairment of oxidative phosphorylation by endotoxin which seems to occur through direct (and/or indirect) toxic cellular effects rather than through impaired tissue perfusion.

REM sleep-associated hemoglobin oxygenation in the monkey forebrain studied using near-infrared spectrophotometry

The oxygenation state of hemoglobin (Hb) in the monkey forebrain was monitored continuously throughout nocturnal sleep using a near-infrared spectrophotometric technique. During rapid eye movement (REM) sleep, an increase in oxygenated Hb occurred concomitantly with a decrease in deoxygenated Hb, while no significant changes in Hb oxygenation were observed during slow wave sleep (SWS). A gradual increase in total Hb content was also observed to occur during each REM sleep episode but not during SWS.

Near-infrared spectrophotometry of eight 3CR radiogalaxies: the first detections of [O III]500.7 and [S III]953.2 emission lines in galaxies with z > 1

Near-infrared spectrophotometry of eight 3CR radiogalaxies: the first detections of [O III]500.7 and [S III]953.2 emission lines in galaxies with z > 1

Near-infrared time-resolved spectroscopy of the cataclysmic variable YY Draconis

view Abstract Citations (35) References (52) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Near-Infrared Time-resolved Spectroscopy of the Cataclysmic Variable YY Draconis Mateo, Mario ; Szkody, Paula ; Garnavich, Peter Abstract Time-resolved near-infrared (8100-8600 A) spectrophotometry and Johnson B-band CCD photometry of the cataclysmic binary YY Dra are presented. The spectra show the presence of the Na I doublet in absorption from the secondary, as well as sharp and broad Ca II emission lines. The sharp Ca II emission lines appear to originate on or near the secondary star because they are visible only during superior conjunction of the secondary star, their radial velocities vary in phase with the Na I absorption lines, and their K-velocity is considerably smaller than observed for the Na I lines. The radial velocity variation of the Na I near-infrared doublet yield an orbital period for YY Dra of P = 0.164988 + or - 0.00023 days. A spectral type of dM 4 + or - 1 for the secondary star is deduced based on the strength of its near-infrared spectral features. The distance to YY Dra is 155 + or - 35 pc based on an application of Bailey's method. Publication: The Astrophysical Journal Pub Date: March 1991 DOI: 10.1086/169823 Bibcode: 1991ApJ...370..370M Keywords: Astronomical Spectroscopy; Binary Stars; Cataclysmic Variables; Line Spectra; Near Infrared Radiation; Astronomical Photometry; Charge Coupled Devices; Dwarf Stars; Emission Spectra; Radial Velocity; Astrophysics; CA II EMISSION; STARS: BINARIES; STARS: DWARF NOVAE; STARS: INDIVIDUAL CONSTELLATION NAME: YY DRACONIS full text sources ADS | data products SIMBAD (5)

Validity of a Near-infrared Device for Estimating Body Composition in a College Football Team

ABSTRACT Near-infrared spectrophotometry (NIR) has been demonstrated to accurately estimate human body composition. The purpose of this investigation was to determine if a new NIR device (Futrex-5000. Futrex Inc., Gaithersburg, MD) obtained accurate estimates of body fat as compared to a criterion method (hydrostatic weighing, HW) in a college football team (n = 91). Values also were compared with three- and seven-site skinfold (SF) estimations. The black athletes were of particular interest since the NIR device has not been independently tested in such a population. The results demonstrated that the NIR device significantly (p 0.05) between HW, three- and seven-site SF estimations. It is concluded that this NIR device does not obtain accurate estimates of body composition in Caucasian or black college football players. Reasons for the variance, as opposed to other NIR techniques, may involve application of a generalized prediction equation to a specific population or use of an inappropriate body site (bicep) as an index of whole-body fat content.

Advances and Perspectives in Near-Infrared Spectrophotometry

Abstract Near-infrared spectrophotometric analysis is a rapid technique that typically uses the reflectance of a solid sample at several wavelengths to determine the sample's composition. A computerized modeling process is generally used to correct for background and sample-matrix interferences. The modeling process employs a training set of samples to, in effect, “teach” the computer to recognize relationships between minute spectral features and sample composition. The contents of the training-set samples must be determined initially by some other reference method before applying the near-IR technique. The model developed from near-IR spectra and reference values gives the sample composition using a number of linear equations. Each of these equations expresses a particular component concentration as a weighted sum of the signals observed at a number of near-IR wavelengths. Instruments used for near-IR spectrophotometry can be as simple as a filter photometer or a grating monochromator. The broad spectra...

Non-invasive monitoring of brain oxygen metabolism during cardiopulmonary bypass by near-infrared spectrophotometry.

A new portable high performance apparatus for near-infrared (NIR) laser spectrophotometry was developed to monitor the oxygenation state of the human brain. Three different wavelengths of the NIR laser beam were used, 780, 805 and 830 nm, to illuminate the head through a fiber optic bundle. The amount of light reflected by or transmitted from the tissue was detected by a photomultiplier or photodiode. Equations as explained here, were used to calculate the oxy and deoxy Hb content and blood volume changes non-invasively. The equations were verified in vivo with the rat head in order to confirm the reliability and acceptability of our methodology. NIR monitoring was applied to 15 cases of cardiopulmonary bypass (CPB) in reflectance mode. The results demonstrated that using current CPB technique, cerebral oxygenation levels during bypass were maintained within the physiological range and changes in brain blood volume corresponded well to the pump flow balance. That is, the brain oxygenation level was maintained roughly constant at a mean perfusion pressure of over 60 mmHg during CPB, whereas below 50 mmHg, apparent decremental changes in oxy Hb content were observed. These findings led us to conclude that non-invasive monitoring of cerebral oxygenation using NIR light can provide valuable bedside data about tissue metabolism and allow for the proper management of critical patients.

Arome, a balloon-borne instrument for astronomical near-infrared spectrophotometry

We present here the French balloon-borne experiment named AROME. This astronomical instrument is specifically designed for the detection of near infrared emission bands (λ=3–12μm) from extended sources of low surface brightness with an angular resolution of 0.5°. The rms sensitivity achieved is of the order of 10-8 Wm-2sr-1, in terms of the power radiated in the 3.3μm band. We recall that this program led to the first detection of the 3.3μm feature in the spectrum of the diffuse galactic emission. The scientific results were presented and interpreted in Paper I, Giard et al., 1989. Future work will include both the observation of fainter objects at 3.3μm and the detection of other emission bands at 6.2 and 11.3μm.