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At least 379 records · Page 21Linked to original sources
PubMed1992

Limitations of laser-Doppler velocimetry and reflectance spectrophotometry in estimating gastric mucosal blood flow.

This study investigated the accuracy of laser-Doppler flowmetry (LDV) and reflectance spectrophotometry (RS) measurements as an index of blood flow in the gastric mucosa of the rat, in experimental conditions such as pharmacologically induced vasoconstriction, hypoxia, hyperoxia, and acute normovolemic anemia. Hydrogen gas clearance was used as a reference method. After vasopressin infusion, LDV signal and indexes of hemoglobin (IHb) and oxygen (ISO2) content in the gastric mucosa estimated by RS significantly decreased in parallel with the reduction of gastric mucosal blood flow (GMBF). Neither hypoxia (5% O2 administration) nor hyperoxia (100% O2) affected GMBF or LDV signal. However, both IHb and ISO2 significantly decreased or increased after hypoxia or hyperoxia, respectively. Acute normovolemic anemia induced a significant increase in GMBF, while LDV signal and ISO2 remained unchanged. IHb significantly decreased in linear relationship with the decrements in the hematocrit. It is concluded that 1) in pharmacologically induced GMBF changes, LDV and RS correlate with GMBF; 2) when changes in hemoglobin saturation are induced, LDV but not RS reflects GMBF; and 3) in acute normovolemic anemia, neither LDV nor RS reflects changes in GMBF.

Anemia↗
PubMed1975

Cerebrospinal fluid spectrophotometry and computerized transverse axial tomography (EMI scanning) in cerebrovascular diseases. Comparative study between two actual diagnostic methods in cerebrovascular disorders.

51 patients with cerebrovascular diseases were examined by CSF spectrophotometry (CSF-SPE) and computerized transverse axial tomography (CTAT: EMI scanning), most cases being followed by several examinations. Specific diagnoses were detected in 98 (CSF-SPE) and 75% (CTAT) of the cases, generally by only one examination. In cases examined angiographically or by isotope encephalography, the corresponding figures were 50 and 0%. The combination of CSF-SPE and CTAT examination obviously means a breakthrough in diagnosis of cerebrovascular diseases which is naturally a prerequisite for the more rational therapy of these common and frequently disabling disorders.

Angiography↗
PubMedDate not supplied

Quantitative reflection spectrophotometry: spatial and temporal variation of Hb oxygenation in human skin.

Applying a fast scanning reflection spectrophotometer and multicomponent spectra analysis, oxygen saturation (SHb) and relative concentration (CHb) of hemoglobin in the skin were determined at eight skin sites in 11 healthy persons. SHb was significantly higher at the tip of the index finger and big toe (90 +/- 3.9 and 92 +/- 4.2%, respectively) compared with the forehead, volar forearm, back of hand, abdomen, calf and forefoot where mean values varied between 52 and 67% (p < 0.001). CHb also was higher at acral sites (big toe: 2.04 +/- 0.14 arbitrary units (AU); index finger: 2.13 +/- 0.19 AU) than at the other locations (p < 0.0001) where it was between 0.56 +/- 0.12 AU (abdomen) and 0.95 +/- 0.28 AU (forefoot). In the course of time, rhythmical oscillations of both parameters at a frequency of 3-5/min were seen in 68% of the measurements, predominantly at the six proximal sites. Heating the measuring site to 44 degrees C caused a biphasic increase of CHb and SHb which was significant at the proximal sites (p < 0.0001). SHb values came into the range of arterial blood. Temporal and spatial variation of both parameters decreased. Reflection spectrophotometry gives the possibility to directly assess dermal hemoglobin saturation, its physiological variability and reactions to provocation stimuli. Concentration and saturation of hemoglobin in dermal vessels appear definitely different at acral compared with proximal sites.

Hemoglobins↗
PubMedDate not supplied

Failure of brain cytochrome alpha , alpha 3 redox recovery after hypoxic hypotension as determined by in vivo reflectance spectrophotometry.

Rats were subjected to a 30 minute period of combined hypoxia (F1o2 = .08) and hemorrhagic hypotension (MAP = 30 mm Hg), then resuscitated by restoration of F1o2 = .30 and reinfusion of shed blood and saline. Intracranial blood volume, hemoglobin saturation, and the cytochrome alpha, alpha 2 redox state were monitored through the intact skull during hypoxic hypotension and after resuscitation utilizing reflectance spectrophotometry. Although resuscitation returned arterial blood pressure, arterial pO2, and hemoglobin saturation toward normal, a sustained, significant (p less than .005) reduction in cytochrome alpha , alpha 2 remained. A parallel series of rats was subjected to identical hypoxic hypotension. At designated intervals the animals were sacrificed to determine brain ATP, ADP, and inorganic phosphate (P1). The data are discussed in terms of relationships between high energy phosphate metabolism and recorded changes in cerebral cytochrome alpha , alpha 2 redox state.

Acid-Base Imbalance↗
PubMed1983

A comparison of two methods for the determination of thallium in urine. Differential pulse anodic stripping voltammetry and flameless atomic absorption spectrophotometry.

Two analytical procedures for the determination of thallium in urine are evaluated and compared. The two methods consist of differential pulse anodic stripping voltammetry and flameless atomic absorption spectrophotometry. Both procedures correlated well and were found to be acceptable in terms of precision and analytical recovery. However, a solvent extraction step proved to be necessary for the AAS procedure, and the linearity with respect to the concentration range was rather limited. The method based on DPASV is simple, accurate, precise, and sensitive and does not require any pretreatment of the sample. We therefore recommend the voltammetric procedure for the determination of thallium in urine, as described in this paper.

Electrochemistry↗
PubMed1981

Reflection spectrophotometry of facial skin.

The color of human skin of 241 whites, blacks, and orientals was measured by reflection spectrophotometry. Among these groups, major differences in luminous reflectance and excitation purity, but not in dominant wavelength, were observed. The twin absorption bands of oxyhemoglobin at 540 and 580 nm were more prominent in whites (particularly females) than in orientals or blacks. Parameters determined for Source A were higher than those for Source C.

Asian People↗
PubMed1983

Application of I.R. spectrophotometry in emergency analyses.

I.R. spectrophotometry has been applied in emergency toxicological analyses. Poisons and drugs are extracted into chloroform, potassium bromide is added to the extract and the solvent evaporated. Potassium bromide discs are prepared by compression and scanned in an I.R. spectrophotometer. A data bank of standard spectra has been prepared and computerized comparison of the spectral data of the sample extract with those of authentic compounds allows the identification of toxic agents in 'real time'.

Barbiturates↗
PubMed1975

Atomic absorption spectrophotometry applied to photographic densitometry.

For this study of photographic densitometry, sections of cartilage stained with Alcian Blue, safranin O and high iron diamine were photographed at x40 with Nikon photomicrography equipment on Kodak Panatomic X film with appropriate filters to enhance contrast. Portions of the developed negative films were selected from intercellular matrix regions, and circles of film equivalent in diameter to a 30-mu circle of tissue were obtained with a hand-held paper punch. Silver was eluted from the circles of film with 35% nitric acid, and the quantity of silver deposited on the film was determined by atomic absorption spectrophotometry as a measure of stain intensity. The intensity determined by this analytic procedure compared favorably with results obtained previously from the same tissue with microspectrophotometry. This method of silver analysis has advantages over earlier studies which used silver elution to determine photographic densitometry in its technical ease, accuracy and sensitivity. Furthermore, this method compares well with microspectrophotometry in its results and has the advantages of relative inexpensiveness and availability of equipment.

Animals↗
PubMed1982

Measurement of tissue disulfide groups by Alcian blue 8GX and atomic absorption spectrophotometry.

The primary purpose of this study was to quantify tissue disulfides with Alcian blue 8GX using atomic absorption spectrophotometry (ASS) to measure the copper moiety of the Alcian blue. The secondary purpose was to determine whether aqueous or alcoholic formalin was a better fixative for this procedure. Sections of mouse renal cortex fixed in 10% neutral formalin (NBF) or in ethanol/formalin/acetic acid (AFA) were stained in 0.5% Alcian blue 8GX in 0.8 M MgCl2 with prior thiosulfation (+Th) or without prior thiosulfation (-Th). The relative contents in the tissues of the copper of Alcian blue, measured by AAS, may be summarized as follows: -Th NBF, 1.15 micrograms Cu/mg tissue; -Th AFA, 1.35 micrograms Cu/mg tissue; +Th NBF, 1.99 micrograms Cu/mg tissue; +Th AFA, 3.25 micrograms Cu/mg tissue. These data indicate that 1) disulfide may be measured by this procedure, and 2) AFA is the preferred fixative for measurement of both disulfides and native sulfates.

Alcian Blue↗
PubMed1994

Cerebrovascular responses to carbon dioxide as detected by near-infrared spectrophotometry: comparison of three different measures.

Near-infrared spectrophotometry can be used to measure cerebral concentrations of oxyhemoglobin and deoxyhemoglobin. This has been applied to developing methods for quantifying cerebral blood volume (CBV), which is relevant for the investigation of the pathogenesis of brain injury in newborn infants as well as older infants. This study investigates the internal consistency between measurements of CBV using two methods: the oxygen method, which is able to determine absolute values of CBV, and the total Hb method, which can detect changes in CBV only. Cerebral blood flow (CBF) was also measured. Fifteen premature infants were examined. Due to practical problems, in only eight of these was a minimum of two CBF and two CBV values obtained both before and after a change in arterial PCO2 of at least 0.5 kPa. A significant difference between the CBV-CO2 reactivity found by the two methods was demonstrated: 0.89 mL/100 g/kPa (95% confidence interval = 0.63-1.26) for the oxygen method and 0.22 mL/100 g/kPa (95% confidence interval = 0.08-0.36) for the total Hb method. This finding is substantiated by the absolute values of CBV [mean value = 3.7 mL/100 g (SD = 1.1)], CBF [mean value = 11.3 mL/100 g/min (SD = 5.9)], and CBF reactivity [59 +/- 9% (SEM)]. All the values correspond well with previous findings, although the CBV reactivity determined by the oxygen method has not been reported previously. The reason for the discrepancy between the two methods is unclear, but induced changes in the scattering properties of the brain would give rise to errors influencing the total Hb method rather than the oxygen method.

Blood Volume Determination↗
PubMed1985

Comparative studies of the diagnostic value of cerebrospinal fluid spectrophotometry and computed tomographic scanning in subarachnoid hemorrhage.

Serial spectrophotometric scans of cerebrospinal fluid (CSF) and computed tomographic (CT) scans of 99 patients with a subarachnoid hemorrhage (SAH) were examined. The xanthochromic index (i.e., the sum of the absorption values at 416 nm (oxyhemoglobin) and 460 nm (bilirubin)) yielded an accurate diagnosis in 82%, as did the CT scan. When both spectrophotometric and CT scans were used, the accuracy of SAH diagnosis increased to 96%. The xanthochromic index was valuable in estimating the date of hemorrhage and also correlated well with the clinical outcome of these patients. Only 42% of the recurrent hemorrhages were diagnosed by CSF spectrophotometry; in this capacity, its role seems less clear. However, a positive diagnosis of recurrent hemorrhage by CT scan was made in 83%.

Adult↗
PubMed1983

The cyanine dye triS-C4(5) as a cationic uncoupler of oxidative phosphorylation: interaction with mitochondria detected by derivative spectrophotometry.

Derivative spectrophotometry was used to study the interaction of the cationic uncoupler triS-C4(5) with mitochondria. The uncoupling action of this dye is dependent on the presence of Pi in the incubation medium. The second derivative spectrum of the dye changed with the incubation period, becoming similar to the spectrum in chloroform; but, after a time, the spectral pattern reverted to the original spectrum. The change in the spectrum in the presence of Pi was much more rapid than in its absence. The degree of spectral change agreed with the relative amount of bound dye determined directly. Thus, the spectral change reflects the binding of dye to the mitochondria, dependent on their energy state. The greater binding without Pi does not cause uncoupling but does cause shrinkage. In contrast, the lesser binding in the presence of Pi causes uncoupling and the swelling of mitochondria. These facts indicate that the dye does not penetrate the mitochondrial membrane. This refutes the idea that uncoupling by lipophilic cations is caused by the electrophoretic transfer of the uncoupler to the mitochondrial matrix space.

Animals↗
PubMed2002

Effect of phosphatidylserine content on the partition coefficients of diazepam and flurazepam between phosphatidylcholine-phosphatidylserine bilayer of small unilamellar vesicles and water studied by second derivative spectrophotometry.

The affinity of the psychotropic benzodiazepine drugs diazepam (DZ) and flurazepam (FZ) to phosphatidylserine (PS) was examined since PS is abundantly contained in brain membranes. The effect of PS content on the partition coefficients (K(p)s) of these drugs between phosphatidylcholine (PC)-PS bilayer membranes of small unilamellar vesicles (SUV) and water was measured using second derivative spectrophotometry. The second derivative spectra of DZ and FZ measured in the solutions containing various amounts of PC-PS SUV clearly showed derivative isosbestic points and a distinct derivative intensity change depending on the amount of the SUV added. The derivative intensity differences (AD) of the drugs before and after addition of the SUV suspension were measured at a specific wavelength. Using the AD values, the Kp values were calculated and obtained with relative standard deviation of below 10%. The Kp values of both drugs increased according to the PS content in the PS-PC bilayer membranes of the SUV proving that both have higher affinity to the PC-PS bilayer membranes than to PC membranes. The effect was much larger for FZ, i.e., the Kp value of FZ at 30 mol% PS content increased to about five times the value for the PC SUV. This can be explained by the fact that at the experimental pH of 7.4, 80% of FZ molecules are in a cationic form (pKa=8.1), so that these molecules are highly accessible to the negatively charged PS molecules. The results support the rapid and high distribution of DZ and FZ in the central nervous system after their administration.

Diazepam↗
PubMed2004

Determination of thiamine HCl and pyridoxine HCl in pharmaceutical preparations using UV-visible spectrophotometry and genetic algorithm based multivariate calibration methods.

Simultaneous determination of binary mixtures pyridoxine hydrochloride and thiamine hydrochloride in a vitamin combination using UV-visible spectrophotometry and classical least squares (CLS) and three newly developed genetic algorithm (GA) based multivariate calibration methods was demonstrated. The three genetic multivariate calibration methods are Genetic Classical Least Squares (GCLS), Genetic Inverse Least Squares (GILS) and Genetic Regression (GR). The sample data set contains the UV-visible spectra of 30 synthetic mixtures (8 to 40 microg/ml) of these vitamins and 10 tablets containing 250 mg from each vitamin. The spectra cover the range from 200 to 330 nm in 0.1 nm intervals. Several calibration models were built with the four methods for the two components. Overall, the standard error of calibration (SEC) and the standard error of prediction (SEP) for the synthetic data were in the range of <0.01 and 0.43 microg/ml for all the four methods. The SEP values for the tablets were in the range of 2.91 and 11.51 mg/tablets. A comparison of genetic algorithm selected wavelengths for each component using GR method was also included.

Algorithms↗
PubMed2005

Influence of medium and temperature on the hydrolysis kinetics of propacetamol hydrochloride: determination using derivative spectrophotometry.

Propacetamol hydrochloride (PRO) is a water-soluble prodrug of paracetamol (PA) which can be parenterally administered as analgesic for the treatment of postoperative pain, acute trauma, and gastric and/or intestinal disorders where oral administration is not possible. In these circumstances, PRO can be administered in physiologic or glucose solutions since it is rapidly and quantitatively hydrolyzed into PA by plasma estearases. We have studied the degradation kinetics of PRO in 5% glucose and 0.9% saline solutions at 4 degrees C and 25 degrees C (storage and room temperatures, respectively). The analytic technique used to determine PRO and PA quantitatively was first-derivative spectrophotometry. The degradation process of PRO can be best fitted to a second-order kinetics with independence of the medium used (saline or glucose solution). The hydrolysis kinetics of PRO conversion into PA depends on the temperature but not on the assay medium (saline or glucose solution). The degradation rate constants obtained for PRO were approximately 4.5 times higher at 25 degrees C than at 4 degrees C. The values of t(90%) for PRO were 3.17 h and 3.61 h at 25 degrees C, and 13.42 h and 12.36 h at 4 degrees C when the tests were performed in 5% glucose and 0.9% saline solutions, respectively.

Acetaminophen↗
PubMed2005

Simultaneous determination of cyproterone acetate and ethinylestradiol in tablets by derivative spectrophotometry.

Derivative spectrophotometry offers a useful approach for the analysis of drugs in multi-component mixtures. In this study a third-derivative spectrophotometric method was used for simultaneous determination of cyproterone acetate and ethinylestradiol using the zero-crossing technique. The measurements were carried out at wavelengths of 316 and 226 nm for cyproterone acetate and ethinylestradiol respectively. The method was found to be linear (r2>0.999) in the range of 0.5-6 mg/100 ml for cyproterone acetate in the presence of 35 microg/100 ml ethinylestsradiol at 316 nm. The same linear correlation (r2>0.999) was obtained in the range of 10-80 microg/100 ml of ethinylestradiol in the presence of 2 mg/100 ml of cyproterone acetate at 226 nm. The limit of determination was 0.5 mg/100 ml and 10 microg/100 ml for cyproterone acetate and ethinylestradiol respectively. The method was successfully applied for simultaneous determination of cyproterone acetate and ethinylestradiol in pharmaceutical preparations without any interferences from excipients.

Calibration↗
PubMed1991

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.

Animals↗
PubMed1991

[Determination of zinc in very small body hair samples by one-drop flame atomic absorption spectrophotometry].

A method for determination of zinc contents in very small samples of hair was developed in order to estimate the zinc concentration in the human body. All steps from weighing of samples to ashing and preparation of the test solution were done in a tube designed by us to prevent contamination and to improve handling. Zinc concentration was determined with flame atomic absorption spectrophotometry aspirating a small volume of samples (80 microliters), by the so-called "one-drop method". Using this method, 5 mg of whiskers was analyzed every day for 10 days, and this revealed that the fluctuation of the zinc concentration level was very small and that it was possible to trace the individual level of zinc concentration daily. A sample of 5 mg is enough for the application of this method. Zinc concentration in the hair under the temple of a boy, and even the low-level zinc content of patients receiving total parenteral nutrition could be accurately determined every 10 days and monthly, respectively. The level of hair zinc contents for neonates was similar to that of adults.

Adult↗