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PubMed1995

[Clinical study on measurement of cerebral metabolism and oxygenation during cardio-pulmonary bypass by near-infrared spectrophotometry].

We studied the non-invasive method of monitoring of cerebral metabolism and oxygenation of patients mainly with thoracic aortic aneurysm during Cardio-pulmonary bypass (CPB) by Near-infrared Spectrophotometry (NIRS) to establish the safety limits of cerebral perfusion. NIRS monitoring of all 12 patients showed that cerebral oxygenation levels were maintained within the pre-CPB range when mean arterial perfusion pressure (MAPP) was above 60 mmHg. With considering rectal temperature, the cerebral oxygenation levels were maintained above the pre-perfusion baseline when MAPP was above 50 mmHg at rectal temp. < or = 25 degrees C, and 73 mmHg at > or = 25 degrees C. It was suspected that cerebral autoregulatory mechanism could exist even in hypothermia (< or = 25 degrees C) because cerebral oxy-Hb and blood volume was significantly declined when MAPP was reduced to 40 mmHg or less. In 5 patients who underwent selective cerebral perfusion, the base line level of blood volume was preserved when the perfusion flow rates were above 0.5l/min, and the desirable oxy-Hb levels were obtained when the flow rates were above 0.4l/min. During deep hypothermic circulatory arrest (18 degrees C), cerebral oxy-Hb level was gradually reduced from baseline, reflecting proceeding metabolic activity even in profound hypothermia. These findings led us to conclude that non-invasive, continuous, and direct monitoring of cerebral oxygenation using NIRS can provide valuable data to prevent cerebral injury after CPB. It is hoped that the safety limits of cerebral perfusion and circulatory arrest can be established in the future using multiple analysis of pressure, flow, temperature, Hb concentration and so far by NIRS.

Aged↗
PubMed1995

Determination of paraquat in biologic materials by a simplified solid phase extraction and spectrophotometry.

A rapid measurement of low paraquat levels in body fluids is important for diagnosis and prognosis of paraquat intoxication. A simple and sensitive method for the determination of submicrogram levels of paraquat by solid phase extraction in conjunction with spectrophotometry has been developed. Serum, urine and formalin from fixed tissue were passed through this column and paraquat was eluted with 2 mL 2N NaOH. The eluent was reduced with dithionite and spectrophotometrically quantified with the zero- or second-order derivative. The detection limits of paraquat by this method are 0.05 mg/L and 0.01 mg/L with the zero-order and 0.005 mg/L and 0.001 mg/L with the second-order derivative, using 2 mL of serum and 10 mL of urine or formalin. The proposed method prevents the interference of biologic specimens as well as providing high extraction efficiency and good precision. The entire procedure can be completed within 30 minutes without special skills, reagents or equipment. These results show that this method is suitable for clinical and forensic toxicologic purposes.

Chromatography, Gel↗
PubMed1995

Sensitive method for analysis of strontium in human and animal plasma by graphite furnace atomic absorption spectrophotometry.

For long-term pharmacokinetic studies in humans as well as in experimental animals, an analysis of strontium (Sr) with a low detection limit and high sensitivity is necessary. The data presented here describe the optimization of the furnace program and sample handling for measuring Sr in plasma by using graphite furnace atomic absorption spectrophotometry. The method was validated and applied to studies on the pharmacokinetics of SrCl2 in humans and rats. Calibration curves were linear up to 57.1 nmol/L. The limit of detection and lower limit of quantification were 0.21 and 0.57 nmol/L, respectively. Reciprocal sensitivity was 0.53 nmol/L Sr at A = 0.0044. The intraassay precision was 2.2%, 1.5%, and 1.1% (n = 6) at 4.57, 22.7, and 49.2 nmol/L Sr, respectively. At these concentrations, the interassay precision and recovery were 0.7%, 1.5%, and 1.8% and 100.4%, 99.1%, and 100.6% (n = 12), respectively. The endogenous Sr concentration in human plasma samples was 0.27 +/- 0.07 mumol/L (n = 18). Pharmacokinetic studies in a human volunteer and in rats demonstrated that this procedure was suited for measuring low Sr concentrations and was applicable to small sample volumes.

Adult↗
PubMed1995

[Non-invasive monitoring of cerebral oxygenation by NIR spectrophotometry (clinical trial)].

A Shimazu OM-100A near infrared spectrophotometer was used to monitor the cerebral oxygenated hemoglobin (Oxy-Hb), deoxygenated hemoglobin (Deoxy-Hb) and total hemoglobin (Total-Hb) in 3 patients with a) massive hemorrhage, b) ruptured aneurysm in the abdominal aorta, or c) hypercapnia. The hematocrit value of the patient with massive hemorrhage decreased rapidly to 18 %; the Total-Hb and Oxy-Hb also decreased significantly. Red blood cell transfusion raised the Oxy-Hb level, indicating an improvement in cerebral oxygenation. In the patient with a ruptured aneurysm, changes in blood flow brought about by clamping or declamping of the abdominal aorta were immediately reflected by corresponding changes in Total-Hb and Oxy-Hb. Oxy-Hb increased significantly and correlated well with the PETCO2 value in the patient with hypercapnia. Thus, NIR spectrophotometry is a useful non-invasive tool which can monitor metabolic and hemodynamic changes in the brain in various pathological conditions.

Adult↗
PubMed1995

Cerebral oxygenation and hemodynamics during induction of extracorporeal membrane oxygenation as investigated by near infrared spectrophotometry.

OBJECTIVE: To investigate cerebral oxygenation and hemodynamics in relation to changes in some relevant physiologic variables during induction of extracorporeal membrane oxygenation (ECMO) in newborn infants. METHODS: Twenty-four newborn infants requiring ECMO were studied from cannulation until 60 minutes after starting ECMO. Concentration changes of oxyhemoglobin (cO2Hb), deoxyhemoglobin (cHHb), total hemoglobin (ctHb), and (oxidized-reduced) cytochrome aa3 (cCyt.aa3) in cerebral tissue were measured continuously by near infrared spectrophotometry. Heart rate (HR), transcutaneous partial pressures of oxygen and carbon dioxide (tcPO2 and tcPCO2), arterial O2 saturation (saO2), and mean arterial blood pressure (MABP) were measured simultaneously. Intravascular hemoglobin concentration (cHb) was measured before and after starting ECMO. In 18 of the 24 infants, mean blood flow velocity (MBFV) and pulsatility index (PI) in the internal carotid and middle cerebral arteries were also measured before and after starting ECMO using pulsed Doppler ultrasound. RESULTS: After carotid ligation, cO2Hb decreased whereas cHHb increased. After jugular ligation, no changes in cerebral oxygenation were found. At 60 minutes after starting ECMO, the values of cO2Hb, saO2, tcPO2, and MABP were significantly higher than the precannulation values, whereas the value of cHHb was lower. There were no changes in cCyt.aa3, tcPCO2, and HR, whereas cHb decreased. The MBFV was significantly increased in the major cerebral arteries except the right middle cerebral artery, whereas PI was decreased in all measured arteries. Cerebral blood volume, calculated from changes in ctHb and cHb, was increased in 20 of 24 infants after starting ECMO. Using multivariate regression models, a positive correlation of delta ctHb (representative of changes in cerebral blood volume) with delta MABP and a negative correlation with delta tcPO2 were found. CONCLUSIONS: The alterations in cerebral oxygenation after carotid artery ligation might reflect increased O2 extraction. Despite increase of the cerebral O2 supply after starting ECMO, no changes in intracellular O2 availability were found, probably because of sufficient preservation of intracellular cerebral oxygenation in the pre-ECMO period despite prolonged hypoxemia. The increase in cerebral blood volume and cerebral MBFV may result from the following: (1) reactive hyperperfusion, (2) loss of autoregulation because of prolonged hypoxemia before ECMO and/or decreased arterial pulsatility, or (3) compensation for hemodilution related to the ECMO procedure.

Brain↗
PubMedDate not supplied

Analysis of calcium and lead in calcium supplements by inductively coupled plasma-atomic emission spectrometry and graphite furnace atomic absorption spectrophotometry.

A method was developed to analyze various calcium supplements for Ca and Pb content. The analysis involves a dry ash of the supplements followed by wet digestion. The Pb is determined by graphite furnace atomic absorption spectrophotometry (GFAAS). Analysis of Ca is by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Ca supplements fortified with Pb at levels ranging from 0.25 to 10.0 micrograms/g yielded recoveries ranging from 82.7 +/- 4.2 to 105.0 +/- 1.7%. To test accuracy, the method was applied to National Institute of Standards and Technology standard reference materials (NIST SRMs) 1572 citrus leaves and 1486 bone meal. GFAAS analysis of SRM 1572 averaged 13.1 +/- 0.6 micrograms Pb per g (certificate value, 13.3 +/- 2.4 micrograms Pb per g), and analysis of SRM 1486 averaged 1.34 +/- 0.11 micrograms Pb per g (certificate value, 1.335 +/- 0.014 micrograms Pb per g). ICP-AES analysis of SRM 1572 averaged 3.12 +/- 0.01% Ca (certificate value, 3.15 +/- 0.10% Ca by weight), and analysis of SRM 1486 averaged 27.63 +/- 0.27% Ca (certificate value, 26.58 +/- 0.24% Ca). The method's limit of quantitation (LOQ), on supplement Ca basis and a 1 g sample, averaged 0.75 micrograms Pb per 1 g Ca for supplements containing 9 to 35% Ca by weight. At a Pb level of 0.663 micrograms/g Ca, the reproducibility relative standard deviation (RSDr) averaged 7.3% and the repeatability relative standard deviation (RSDR) averaged 8.0%. It is recommended that the method be studied collaboratively.

Calcium↗
PubMed1976

[Determination of erythrocyte zinc by atomic absorption spectrophotometry: Its significance in iron deficiency anemia (author's transl)].

Present investigation was undertaken to elucidate the significance of changes in erythrocyte zinc levels in anemia. A preliminary study for the determination of erythrocyte zinc by atomic absorption spectrophotometry was done. The simple dilution method, in which zinc was determined directly from a sample of erythrocyte lysed and diluted with deionized water, appeared satisfactory in view of its rapidity, simplicity and accuracy. Of importance is that the temperature of sample and standard solution had to be matched. By using the above method, the mode of changes in erythrocyte zinc levels was investigated in healthy individuals and it was found that erythrocyte zinc expressed per gram of hemoglobin was inversely correlated to mean corpuscular hemoglobin concentration (MCHC). This relationship was also shown in patients with iron deficiency anemia and phlebotomy-induced anemia in rabbits. However, erythrocyte zinc expressed per milliliter of packed red cells was generally increased in these cases. The difference of erythrocyte zinc levels between 9:00 a.m. and 3:00 p.m. was not statistically significant. In addition, the levels of the B and of the C type erythrocyte carbonic anhydrases were assayed immunochemically. It was ascertained that there was a significant correlation between erythrocyte zinc levels and those of total carbonic anhydrase. This, the clinical importance of changes in erythrocyte zinc levels in anemia was discussed in relation to the role of this zinc - metalloenzyme.

Adolescent↗
PubMed1977

Determination of plasma and erythrocyte lithium concentrations by atomic absorption spectrophotometry.

We describe a method for determining plasma and erythrocyte lithium concentrations by atomic absorption spectrophotometry. Plasma and hemolyzed whole-blood are diluted and analyzed, with use of a lithium hollow-cathode lamp, at 670.8 nm. Erythrocyte lithium concentrations are calculated indirectly from the hematocrit. The standard deviation for a 0.43 mmol/liter pool of whole blood, run daily over 11 months, was +/-20 mumol/liter (CV=5.1). The lithium concentration of a lyophilized pool assayed periodically over the same period (n=127) was 1.84+/-0.05 mmol/liter (CV=2.7%). The relatively low erythrocyte/plasma lithium ratio and the microhematocrit centrifugation force (9600 to 13 600 X g) make corrections for trapped plasma insignificant. Problems with matrix matching and viscosity are overcome by using a plasma pool standard for calculations. Values for erythrocyte lithium concentrations were unchanged in samples stored at room temperature up to 24 h. Hemolysis appears to be of possible clinical significance. This method is useful as a routine clinical laboratory procedure for monitoring patients with affective disorders, who are undergoing therapy with lithium.

Erythrocytes↗
PubMedDate not supplied

Determination of metals in foodstuffs by atomic absorption spectrophotometry after dry ashing: NMKL interlaboratory study of lead, cadmium, zinc, copper, iron, chromium, and nickel.

An interlaboratory study of a method for determination of lead, cadmium, zinc, copper, iron, chromium, and nickel in foodstuffs by atomic absorption spectrophotometry (AAS) after dry ashing at 450 degrees C was conducted in 16 laboratories. The study was preceded by a practice round of familiarization samples and another round in which solutions were distributed and the metals were determined directly by AAS. The study included 5 different foods (liver paste, apple sauce, minced fish, wheat bran, and milk powder) and 2 composite diets. A single analysis was carried out on each sample. Suitable sample combinations were used as split level combinations for determination of the repeatability standard deviation. The relative reproducibility standard deviation for each of the elements ranged as follows: lead, 74-18% at 0.025-0.28 mg/kg; cadmium, 80-11% (0.002-0.51 mg/kg); zinc, 12-7% (44-72 mg/kg); copper, 47-10% (0.48-41 mg/kg); iron, 35-9% (2-228 mg/kg); chromium, 48-21% (0.008-0.22 mg/kg); nickel, 64-39% (0.025-0.39 mg/kg).

Dairy Products↗
PubMedDate not supplied

Simultaneous determination of flavor enhancers inosine 5'-monophosphate and guanosine 5'-monophosphate in food preparations by derivative spectrophotometry.

A derivative spectrophotometric method was developed for the quantitative determination of 2 flavor enhancers, inosine 5'-monophosphate (IMP) and guanosine 5'-monophosphate (GMP), in the presence of monosodium glutamate (MSG). Procedures for determining IMP and GMP singly and in binary mixtures are described. Overlapping absorption spectra of both compounds were resolved by using first-derivative spectrophotometry. By measuring the first-derivative signals of IMP and GMP at 253 and 248 nm, respectively, simultaneous determination was possible for IMP and GMP at 5-40 micrograms/mL, in the presence of up to 5000 micrograms/mL MSG. The method was satisfactorily used to determine IMP and GMP in several food preparations.

Flavoring Agents↗
PubMedDate not supplied

Determination of chromium and molybdenum in medical foods by graphite furnace atomic absorption spectrophotometry.

Graphite furnace atomic absorption spectrophotometry was used to determine chromium and molybdenum in 7 medical foods from 5 manufacturers. Linear standard curves were obtained for both elements for concentrations between 5 and 25 ng/mL. Detection limits were 0.24 ng/mL for Cr and 0.67 ng/mL for Mo. Characteristic masses were 3.1 and 14.7 pg for Cr and Mo, respectively. No difference was detected between wet and dry ashing methods, and dry ashing was used to complete the study. The method was validated by assaying various National Institute of Standards and Technology standard reference materials. Analysis of these products for Cr and Mo were within certified values. One product was evaluated by this method for reproducibility (n = 5). Relative standard deviations were 6.8 and 4.8% for Cr and Mo, respectively. This product contained 0.31 +/= 0.02 micrograms Cr/g and 0.63 +/- 0.03 micrograms Mo/g. The remaining products contained 0.09-1.28 micrograms Cr/g and 0.07-2.3 micrograms Mo/g. Mean recovery values were 98 +/- 14% (n = 14) for Cr at spike levels of 0.20-1.89 micrograms/g and 102 +/- 24% (n = 10) for Mo at spike levels of 0.30-1.89 micrograms/g.

Animals↗
PubMed1977

Nickel content of human palatine tonsils: analysis of small tissue samples by flameless atomic absorption spectrophotometry.

We describe a method for determining the nickel content of small tissue samples by flameless atomic absorption spectrophotometry in this case biopsy specimens from human palatine tonsils. Contact between tissue samples and metallic objects was avoided, except for the use of biopsy forceps (Type No. 8150.00 Wolf, stainless steel) for collecting samples, to imitate the actual procedure when small biopsy specimens are removed from the nasal mucosal membranes in nickel workers for histopathological and chemical investigations. Nickel contamination from this instrument was insignificant at the precision of the present procedures. The mean concentration of nickel in 15 tonsils was 13.5 +/- 7.0 (SD) microng/100g (wet wt). The mean nickel concentration in eight different samples of the same tonsil was 5.6 +/- 2.7 (SD microng/100 g.

Adolescent↗
PubMed1996

Analysis of breath alcohol via infrared spectrophotometry: predicting false ethanol results by application of the base-line method to vapor phase infrared spectra.

Toluene and a mixture of the isomeric xylenes are common organic solvents that have been implicated in false ethanol results produced by older models of the Intoxilyzer 5000, a breath alcohol analyzer that uses infrared spectrophotometry to quantitate ethanol in breath samples. A straightforward method is described which predicts this type of interference in analyses conducted on such models. The methodology relies on a comparison of the vapor phase infrared spectra of toluene and xylene with the corresponding spectrum of ethanol, using the base-line method to estimate relative absorbances at the two analytical wavelengths employed by the Intoxilyzer 5000. The point is also made that, given the potential for such interference, a model of the Intoxilyzer 5000 has been developed that has the capability to compensate for this problem.

Breath Tests↗
PubMed1996

[Gastric mucosal congestion following endoscopic variceal ligation--analysis using reflectance spectrophotometry].

UNLABELLED: Endoscopic variceal ligation (EVL) has been accepted as a new treatment for esophageal varices in cirrhotic patients, and evaluated to have a lower incidence of complications compared to sclerotherapy. Sclerotherapy may increase the risk of portal hypertensive gastropathy (PHG), which is recognized to be gastric mucosal congestion due to portal hypertension in cirrhotics. However, the gastric mucosal hemodynamics after EVL has not been established yet. The aim of this study is to assess whether EVL could affect the hemodynamics of the gastric mucosa. PATIENTS AND METHODS: Eleven cirrhotic patients with severe esophageal varices, who underwent prophylactic EVL were enrolled in the trial. Age and sex-matched non-cirrhotic patients who had only gastric mucosal atrophy were entered as control to compare the mucosal hemodynamics to that of cirrhotic patient. EVL was performed as described by Stiegmann et al. The gastric mucosal hemodynamics was evaluated with both gastric mucosal blood volume (IHB) and hemoglobin O2 saturation (ISO2), which were measured by reflectance spectrophotometry during endoscopy. These parameters were measured in the three points of the stomach (gastric antrum, lower corpus and upper corpus) just before and after EVL. RESULT: In all patients with cirrhosis, mild PHG was observed endoscopically. ISO2 in cirrhotic patients was significantly lower in all points of the stomach compared with control. IHB in cirrhotic patients was not significantly different from control. ISO2 of post-EVL was significantly lower than that of pre-EVL, whereas IHB of post-EVL revealed significantly higher than that of pre-EVL. However, endoscopic grade of PHG remained mild. The hemodynamics of the mucosa two weeks after the initial EVL showed improvement of the congestion. CONCLUSIONS: The gastric mucosal hemodynamics showed increment of the gastric blood volume and decreased hemoglobin O2 saturation in cirrhotic patients, indicating that cirrhotic gastric mucosa is in congestive condition. EVL for esophageal varices makes the gastric mucosa more congestive soon after the procedure in spite of the same grade of endoscopic PHG. However, the worsened congestion improves within a few weeks.

Aged↗
PubMed1977

Analysis of foods for arsenic and selenium by acid digestion, hydride evolution atomic absorption spectrophotometry.

A method based on acid digestion, hydride evolution atomic absorption spectrophotometry for estimating microgram and submicrogram quantities of As and Se in foods was developed and evaluated. Samples up to 3 g dry weight were digested with HNO3-HCIO4-H2SO4. As and Se in aliquots of the digests were reduced with NaBH4 to volatile hydrides, using laboratory-constructed and commercially available generators. As and Se were estimated by transient signal atomic absorbance measurements as the hydrides were decomposed in an Ar-H2-entrained air flame. Recoveries of inorganic As and Se added at levels of 0.1-1.0 microgram/g to a variety of foods ranged from 70 to 125%. Analyses of several standard reference samples indicated the method is capable of recovering native analytes. Detection limits for the determinative step and the method as a whole were as low as 5 and 25 ng, respectively, for both elements.

Arsenic↗
PubMed1977

Flameless atomic absorption spectrophotometry of selenium in fish and food products.

A method is described for determining selenium in fish tissues, meat, cereals, milk powder, and other materials by flameless atomic absorption spectrophotometry. Samples are solubilized in HNO3 and atomized in a graphite furnace in the presence of nickel nitrate. Recoveries of 0.500 and 1.000 microgram selenium added to several fish samples averaged 99.0 and 98.3%, respectively, with standard deviations of 5.3 and 4.0. Results agreed with those obtained for samples previously analyzed by fluorometry, and with results for NBS Standard Reference Material. The detection limit was 3 ng/ml solution and 50 ng/g sample.

Fish Products↗
PubMed1997

Evaluation of rectal mucosal hemodynamics in patients with liver cirrhosis using reflectance spectrophotometry.

OBJECTIVES: Portal hypertensive colonopathy is observed in patients with liver cirrhosis. To determine the correlation between rectal mucosal hemodynamics and portal hypertensive colonopathy, we observed rectal mucosal findings and measured rectal mucosal hemodynamics in patients with liver cirrhosis. METHODS: Thirty-four patients with liver cirrhosis and 16 healthy control subjects were simultaneously examined for rectal mucosal findings by colonoscopy and indices of rectal mucosal Hb concentration (RHb) and rectal mucosal oxygen saturation by reflectance spectrophotometry. Endoscopic findings in the rectal mucosa of patients with liver cirrhosis included vascular ectasias, blue veins, and varices. We investigated the relationship between rectal mucosal hemodynamics and clinical parameters of liver cirrhosis (Child-Pugh classification, the amount of indocyanine green remaining in the blood 15 min after its injection, and ascites). Patients with hepatocellular carcinoma, colonic cancer, multiple colonic polyps, or severe anemia were excluded. RESULTS: Rectal mucosal lesions were observed in 11 patients with liver cirrhosis (32.4%). In the hemodynamic studies, we found significantly increased RHb values in the cirrhosis group as compared with the control group. On the other hand, there was no significant change in rectal mucosal oxygen saturation between the two groups. A significant increase in RHb was observed in patients with rectal mucosal lesions in the cirrhosis group. RHb in the cirrhosis group correlated with grade of Child-Pugh classification. Increased RHb decreased in parallel after portal decompression by creation of a transjugular intravenous portosystemic stent shunt. CONCLUSIONS: The rectal mucosal lesions in liver cirrhosis correlate with an increase in RHb, which correlates with portal hypertension.

Ascites↗