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PubMed1995

Postoperative neuropsychological dysfunction and cerebral oxygenation during cardiac surgery.

In 41 patients undergoing cardiac operations with extracorporeal circulation, oxidized cytochrome a,a3(CtO2), deoxygenated hemoglobin (Hb), and oxygenated hemoglobin (HbO2) were measured in brain tissue by near-infrared spectrophotometry (NIRS) intraoperatively. Monitoring also included electroencephalography (EEG) and jugular-bulb venous saturation (SBJO2). All operations were performed using membrane oxygenators, moderate hypothermia (26-28 degrees C) and pH alpha-stat management. During cardiopulmonary bypass (CPB) CtO2 and HbO2) were reduced, reaching minimal values when rewarming was instituted. At the end of the operation CtO2 and HbO2 had regained initial levels. During CPB, arterial PCO2, pH, and temperature were closely related to CtO2 (r = 1000, r = -0.964 and 0.929 respectively; p < 0.001, p < 0.001, and p < 0.003 respectively). Neuropsychological testing by the Mini-Mental-State Test indicated reversible postoperative neuropsychological deficits in four patients. There patients had a lower CtO2 minimum compared to those without these deficits (-4.5 mumol/L v. -0.7 mumol/L; p = 0.036). These findings support the hypothesis that neuropsychological deficits in patients after cardiac surgery can be caused by intraoperative cerebral hypoxia.

Adult↗

PubMed1990

Evaluation of the Fourier transform infrared (FTIR) spectrophotometer for analysis of trichloroethylene (TCE) in the presence of Freon-113 in carbon disulfide eluates of charcoal air sampling tubes.

Results obtained using Fourier transform infrared spectrophotometry (FTIR) for the analysis of samples of carbon disulfide (CS2) eluates containing trichloroethylene (TCE) and Freon from charcoal air sampling tubes were evaluated by comparison with results obtained when using gas chromatography (GC). The FTIR yielded accurate results without regard to the presence of Freon.

Air↗

PubMed1990

Analysis of amphibole asbestos in chrysotile and other minerals.

Chrysotile asbestos and many other mineral raw materials contain amphibole minerals which may be asbestiform. There is currently no analytical method which will detect the presence of amphibole at sufficiently low limits to preclude the possibility of inadvertent exposure of persons handling these materials to hazardous airborne fibre concentrations. A method of chemical digestion of chrysotiles has been tested with regard to the determination of their tremolite contaminant content and this has been applied to a range of chrysotile and other minerals. The method improves the sensitivity of the amphibole analysis at least 10-fold giving detection limits of 0.01-0.05% in chrysotile by X-ray diffractometry (XRD). The difficulties arising from compositional and morphological variations are discussed in the context of the potential hazards from airborne fibres and the relative values of analyses by XRD, infrared spectrophotometry (IR) and electron microscopy. It is concluded that XRD and IR are useful as screening methods for the detection of amphibole in chrysotile but other materials should be analysed by optical or electron microscopy.

Asbestos↗

PubMedDate not supplied

Suicidal poisoning by endothall.

A fatal case of suicidal ingestion of the herbicide endothall (7-oxabicyclo [2,2,1]heptane-2,3-dicarboxylic acid) is described. Endothall was determined after initial phosphotungstic acid deproteination followed by extraction using 1,2-dichloroethane:tert-butanol (2:1) and subsequent injection into the gas chromatograph equipped with a flame ionization detector. Identity was confirmed by thin-layer chromatography, infrared spectrophotometry, and gas chromatography/mass spectrometry.

Adult↗

PubMed1997

Rhodamine 800 as a probe of energization of cells and tissues in the near-infrared region: a study with isolated rat liver mitochondria and hepatocytes.

To examine the feasibility of optical monitoring of cellular energy states with tissue-transparent near-infrared (NIR) light, the absorption and fluorescence characteristics of Rhodamine 800 in isolated rat liver mitochondria and hepatocytes were investigated. When the dye was incubated with isolated mitochondria, a large red shift of the absorption spectra and quenching of the fluorescence intensity were observed. The absorbance difference at 730 minus 685 nm, or at 730 minus 800 nm, and the fluorescence intensity measured at 692 nm varied linearly with the mitochondrial membrane potential. The spectral changes observed could be explained in terms of the potential-dependent uptake of the dye from the buffer solution into the mitochondrial matrix. The respiration control ratio and oxygen consumption rate were not affected by the addition of Rhodamine 800 at concentrations lower than 5 microM, which was the concentration range mostly employed throughout the present study. In a suspension of hepatocytes, the red shift and fluorescence quenching of Rhodamine 800 characteristic of energized mitochondria were also observed, and these changed to those of the buffer solution with the addition of an uncoupler under normoxia. At the early stage of anoxia, within about 5 min, when cytochrome oxidase was completely reduced, hepatocytes were concluded to be in the fully energized state, since the optical characteristics of Rhodamine 800 were the same as those of energized mitochondria. On the basis of these in vitro data, Rhodamine 800 is concluded to be a possible NIR-active contrast agent, that can be used to monitor the energy states of living tissues, in addition to the tissue oxygenation states, by the use of near-infrared spectrophotometry (NIRS) without harmful effects.

Adenine↗

PubMed1988

Failure of autoregulation after closed head injury: an experimental model.

Cats were subjected to a 3.5-atm fluid percussion impact administered to the cerebral cortex. Near-infrared spectrophotometry (NIRS) was used to measure the quantity of oxyhemoglobin and total hemoglobin in the illuminated tissue as well as the cytochrome a, a3 redox state. Corroborative data were obtained by freezing brains with liquid nitrogen and measuring cortical concentrations of ATP, creatine phosphate (CP), and lactate. Immediately postimpact there was a rise in mean arterial pressure with a 38% increase of highly oxygenated blood and a shift toward oxidation in the cytochrome a, a3 redox state. By 4 hours postimpact, cytochrome a, a3 was becoming progressively reduced despite the persistence of hyperemia. This was associated with a significant (p less than 0.01) decrease in ATP and CP concentration. Additional studies in which a 0.5-sec, 100-v electrical seizure was induced before and after fluid percussion demonstrated significant differences in seizure response, indicating a failure of autoregulation.

Adenosine Triphosphate↗

PubMed2001

Hemoglobin/myoglobin oxygen desaturation during Alpine skiing.

PURPOSE: To investigate muscle blood volume (BV) change and hemoglobin/myoglobin oxygen desaturation (OD) during simulated giant slalom (GS) and slalom (SL) Alpine ski racing. METHODS: Joint angle, BV, OD, and heart rate (HR) were evaluated during GS and SL events in 30 junior elite skiers ages 9--17 yr (13.5 +/- 2.3). Subjects were stratified by ski class and age: group I, J1 and J2, ages 15--18 yr (16.8 +/- 0.8); group II, J3, 13--14 yr (13.6 +/- 0.7); and group III, J4 and J5, 9--12 yr (11.5 +/- 1.2). Near-infrared spectrophotometry (NIRS) was used to measure BV and OD in the capillary bed of the vastus lateralis during trials. Maximal OD was determined during thigh cuff ischemia (CI). Quadriceps cross-sectional area (CSA) was estimated by skin-fold and thigh circumference. RESULTS: Joint angles were smaller (P < 0.05) during GS than SL for ankle (83.8 +/- 11.9 degrees; 98.6 +/- 15.7 degrees ), knee (107.4 +/- 14.9 degrees; 118.3 +/- 18.0 degrees ), and hip (98.8 +/- 14.3 degrees; 107.5 +/- 16.2 degrees ). BV reduction from rest to peak exercise (Delta BV) was 30% greater (P < 0.05) during the GS than SL, whereas Delta OD was 33% greater (P < 0.05) during GS. Delta OD, relative to CI OD, was greater for all subjects during GS (79.2 +/- 3.7%) than SL (65.7 +/- 4.4%). This pattern continued within groups; group II displayed the greatest relative desaturation (82.9 +/- 7.6%). CSA was larger in older skiers (92.5 +/- 21.6; 72.5 +/- 12.3; 65.3 +/- 21.2 cm(2)) and correlated with Delta OD (P < 0.05). CONCLUSION: The larger reduction in BV (Delta BV change) and greater OD when skiers assumed lower posture during GS than SL may be related to greater effective static load secondary to higher percent of maximal voluntary contraction and is consistent with compromised blood flow to working muscle.

Adolescent↗

PubMed1995

The influence of arterial carbon dioxide on cerebral oxygenation and haemodynamics during ECMO in normoxaemic and hypoxaemic piglets.

OBJECTIVE: To investigate the cerebrovascular response to changes in arterial CO2 tension during extracorporeal membrane oxygenation (ECMO) in normoxaemic and hypoxaemic piglets. METHODS: Four groups of six anaesthetized, paralysed and mechanically ventilated piglets: group 1-normoxaemia without ECMO, group 2-ECMO after normoxaemia, group 3-hypoxaemia without ECMO, and group 4-ECMO after hypoxaemia, were exposed successively to hypercapnia and hypocapnia. Changes in cerebral concentrations of oxyhaemoglobin (cO2Hb), deoxyhaemoglobin (cHHb), (oxidized-reduced) cytochrome aa3 (cCyt.aa3) and blood volume (CBV) were continuously measured using near infrared spectrophotometry. Heart rate, arterial O2 saturation, arterial blood pressure, central venous pressure, intracranial pressure (ICP) and left common carotid artery blood flow (LCaBF) were measured simultaneously. RESULTS: Hypercapnia resulted in increased CBV, cO2Hb and ICP in all groups, while cHHb was decreased. No changes in LCaBF were found. Hypocapnia resulted in decreased cO2Hb and increased cHHb except in group 3. LCaBF decreased in all groups except group 2. CBV decreased only in groups 2 and 4. No effect on ICP was observed in any of the groups. The other variables showed no important changes either during hypercapnia or hypocapnia. ECMO after hypoxaemia resulted in a greater response of cO2Hb and cO2Hb and cHHb during hypocapnia. The effect of hypercapnia on CBV while on ECMO was greater than without ECMO. CONCLUSION: Since cerebrovascular reactivity to CO2 remains intact during ECMO in piglets, it is important to keep arterial CO2 tension stable and in normal range during clinical ECMO.

Anesthesia, General↗

PubMed1990

Effect of beta-glucanases on Penicillium oxalicum cell wall fractions.

The polysaccharidic effect of a purified 1,3-beta-glucanase, a purified beta-glucosidase, and of partially purified endo-1,3-beta-glucanase from autolysed Penicillium oxalicum cultures on cell wall isolate fractions from the same fungus were studied. Fractionation of 5-day-old cell wall gave rise to a series of fractions that were identified using infrared spectrophotometry. The fractions used were: F1, an alpha-glucan; F3, a beta-glucan; F4, a chitin-glucan; and F4b, a beta-glucan. The fractions were incubated with each of the enzymes and with a mixture of equal parts of the three enzymes and the products of the enzymatic hydrolysis were analyzed after 96 h incubation. The enzymes were found to degrade fraction F4b (beta-glucan); the greatest degree of hydrolysis was reached when the three enzymes were used together, suggesting the need for synergic action by these enzymes in the cell wall degradation process.

Cell Wall↗

PubMed1992

Physiochemical interactions of praziquantel, oxamniquine and tablet excipients.

A differential scanning calorimetry and infrared spectrophotometry study of potential interactions between oxamniquine and praziquantel, two synergistic anti-parasitic drugs, indicated that they did not interact on fusion. Mixtures of the two drugs with each of nine common pharmaceutical excipients (Ac-Di-Sol, Avicel, Crospovidone, calcium phosphate, magnesium stearate, starch, lactose, PEG 6000, stearic acid) appeared to interact only with stearic acid. These results suggested that a combination solid dosage form was feasible.

Calorimetry, Differential Scanning↗

PubMed1992

Comparison of four methods to assess body composition in black and white athletes.

Four methods of assessing body composition were compared in 55 black and 35 white, Division I, American football players. Percent body fat (%BF) was estimated with hydrostatic weighing at residual volume, corrected for race; seven-site skinfolds (7 SF), corrected for race; bioelectrical impedance analysis (BIA); and near-infrared spectrophotometry (NIR). Percent body fat with HW in blacks (mean = 14.7%) and whites (19.7%) did not differ (P > .05) from %BF with 7 SF (blacks, 14.7%; whites, 19.0%). In relation to HW, BIA significantly (P < .05) overpredicted (blacks: 20.1%, SEE = 3.2%; whites: 22.3%, SEE = 4.3%) and NIR underpredicted %BF (blacks: 12.6%, SEE = 3.9%; whites: 17.7%, SEE = 3.6%). The contribution of BIA variables (resistance, phase angle, conductance) and NIR optical density to predict %BF was trivial compared to body mass index. It appears that race may not substantially influence %BF prediction by NIR and BIA. It was concluded that when considering the cost and expertise required with NIR and BIA, SF measurements appear to be a superior alternative for rapid and accurate body composition assessment of athletes, independent of race.

Adolescent↗

PubMed1958

An infrared study of the hydrolysis of a thiazolidine.

The hydrolysis in aqueous solution of L-4-carboxy-2,2-dimethylthiazolidine hydrochloride has been followed by infrared spectrophotometry. The absorption curve of the final reaction mixture had absorption characteristics which were also shown by a solution containing stoichiometric amounts of the expected reaction products.

Hydrolysis↗

PubMed1993

Seven-day validation of doubly labeled water method using indirect room calorimetry.

Carbon dioxide production, water production, and energy expenditure (EE) determined with 2H2(18)O were validated using a room calorimeter. Nine human subjects (5 males, 4 females) resided in the calorimeter for five to seven consecutive 23.5-h days. Daily carbon dioxide and water production and EE were averaged from calorimeter data and compared with 2H2(18)O results for the same period and for the following week. Isotope concentrations were measured by isotope ratio mass spectroscopy (18O) and infrared spectrophotometry (2H). Isotope clearance rates and pool sizes were determined by two multipoint methods and the two-point method. No significant differences were measured between calorimetry and 2H2(18)O results for the period within the chamber [multipoint A.M. urine 1.55% +/- 2.57 (SD) %, multipoint A.M. + P.M. urine 0.98% +/- 8.19%, two-point 1.59% +/- 4.50%]. Free-living EE was 13% +/- 7% greater. The results indicate that the 2H2(18)O method as applied is a valid technique for measuring EE, that multipoint calculation methods can be as precise as the two-point method, and that EE was greater in free-living than in calorimeter-confined conditions.

Adult↗

PubMed1996

Impact of central, obstructive and mixed apnea on cerebral hemodynamics in preterm infants.

The objective of this study was to evaluate the effect of central, obstructive and mixed apnea on cerebral total hemoglobin concentration (tHb), which is analogous to cerebral blood volume, and to investigate whether tHb alterations correlate with bradycardia and arterial desaturation. Measurements were carried out on 17 preterm infants (gestational age 26-30 weeks) with frequent apneic events. Near infrared spectrophotometry (NIRS) was used to quantify changes in tHb. Respiration was monitored by chest movements using impedance pneumography and by nasal airflow using a thermistor. In addition, heart rate, arterial oxygen saturation, in each infant and esophageal pressure in 3 babies were continuously recorded. 130 apneic episodes of > 10 s duration showed four different patterns of tHb alterations: (1) no change in tHb (28%); (2) isolated decrease (35%); (3) isolated increase (12%), or (4) both combined, an initial decrease followed by an increase over the previous baseline level (25%). Obstructive apneic episodes were associated with a significantly greater maximum fall in tHb (median 11.5; 5th percentile 0 and 95th percentile 30.5 mumol/l) compared to mixed (4.9, 0 and 26.4 mumol/l) and central events (3.0, 0 and 14.0 mumol/l). Changes in tHb correlated with heart rate only in purely central apnea and were not reflected in arterial oxygen saturation in any type of apnea. Obstructive apnea was observed to have the strongest impact on tHb. As these tHb alterations may exacerbate or cause intraventricular hemorrhage, efforts must be made to prevent obstruction of upper airways and to focus monitoring on cerebral perfusion.

Apnea↗

PubMed1995

Determinants of cerebral oxygenation during cardiac surgery.

BACKGROUND: Neuropsychological deficits after cardiac surgery are attributed to the side effects of cardiopulmonary bypass (CPB). To protect the brain from ischemic damage, the influences of temperature, blood pressure, blood gases, acid-base status, and hemodilution on cerebral oxygenation have to be elucidated and quantified. METHODS: Forty-one consecutive patients were investigated during cardiac surgery while on CPB. Operative management included moderate hypothermia of 26 degrees C and the alpha-stat pH management. With near-infrared spectrophotometry, changes in oxygenated hemoglobin (HbO2, representing oxygen delivery) and oxidized cytochrome a,a3 (CtO2, cellular oxygenation) in brain tissue were obtained noninvasively. In addition, venous saturation of the brain was measured via a catheter in the jugular bulb (SBJO2). The influence of operative management parameters on cerebral oxygenation was calculated by univariate and multiple regression analyses. RESULTS: Before and after CPB there was no significant multivariate determinant of cerebral oxygenation. During CPB, HbO2 depended solely on PCO2 (P < .01; r = .89). CtO2 was determined by pH (P < .01), esophageal temperature (P < .01), PCO2 (P < .01), and Hb (P < .01). These parameters explained nearly all changes of the cytochrome measurements during CPB (r = .99). Arterial PCO2 (P < .01) and pH (P < .01) influenced brain venous oxygen saturation (SBJO2; r = .98). CONCLUSIONS: Cerebral oxygenation is autoregulated during cardiac surgery before and after CPB. During CPB, Hb, temperature, pH, and PCO2 determined at least 85% of all changes in cerebral oxygenation. The main causes of impaired cerebral oxygenation are the decrease in Hb with hemodilution, vasoconstriction due to hypocapnia, and the leftward shift of the Hb binding curve in alkalosis and hypothermia.

Adult↗

PubMed1997

Effects of irradiation of an erbium:YAG laser on root surfaces.

The application of erbium:YAG laser (Er:YAG) irradiation has been investigated for periodontal therapy. The purpose of this study was to evaluate the effects of Er:YAG laser irradiation on root surfaces using a scanning electron microscope (SEM) and to determine the laser's ability to remove lipopolysaccharides (LPS). Infrared spectrophotometry was used to investigate the effects of the laser on LPS applied to root dentin pellets. Premolars extracted for orthodontic reasons were prepared for this study. The crowns were resected below the cemento-enamel junction, longitudinally sectioned, and the contents of the pulp chamber were removed. Then 15 root tips (5 x 5 x 1 mm) were classified into 3 groups of 5 each as follows: group 1, tips without any treatment; group 2, planed tips with the cement layers left untouched; and group 3, planed until the dentin surface was disclosed. The center of each specimen was used as the experimental irradiated area and the peripheral area served as a control. The quantity of vapor delivered by Er:YAG laser was highly increased, and the irradiated areas displayed little morphogenetic changes. The lyophilized sample LPS 0111 B4 from E. coli was then mixed with potassium bromide and pressed into a tablet, which was examined at 4,000-650 Kayser. The lyophilized LPS had a peak at 2.94 microns. LPS on the root dentin pellets was cleared away as much as possible by 150 washings in pyrogen-free water using an ultrasonic cleaner. Five microliters of 24 EU LPS solution was dropped on the root dentin pellets, which were then irradiated by the Er:YAG laser, and washed using the ultrasonic cleaner in pyrogen-free water. The amount of the extracted LPS solution was determined by spectrophotometer at 405 nm. The Er:YAG laser could remove 83.1% of the LPS. This study suggests that Er:YAG laser irradiation might be useful for root conditioning in periodontal therapy. However, clinical testing is necessary to establish what, if any, utility the Er:YAG laser has as a part of periodontal therapy.

Aluminum Silicates↗

PubMed1986

Evaluation of physical health effects due to volcanic hazards: crystalline silica in Mount St. Helens volcanic ash.

This investigation has shown that crystalline silica has been identified as being present in the Mount St. Helens volcanic ash at levels of 3 to 7 per cent by weight. This identification has been established using X-ray powder diffraction, infrared spectrophotometry, visible spectrophotometry, electron microscopy, and Laser Raman spectrophotometry. Quantitative analysis by IR, XRD, and visible spectrophotometry requires a preliminary phosphoric acid digestion of the ash sample to remove the plagioclase silicate material which interferes with the determination by these methods. Electron microscopic analysis as well as Laser Raman spectrophotometric analysis of the untreated ash confirms the presence of silica and at levels found by the XRD and IR analysis of the treated samples. An interlaboratory study of volcanic ash samples by 15 laboratories confirms the presence and levels of crystalline silica. Although several problems with applying the digestion procedure were observed in this hastily organized supply, all laboratories employing the digestion procedure reported the presence of crystalline silica. These results unequivocally put to rest the question of the presence of silica in the volcanic ash from eruptions of Mount St. Helens in 1980.

Disasters↗

PubMed1998

Characterization of urinary calculi: in vitro study of "twinkling artifact" revealed by color-flow sonography.

OBJECTIVE: The "twinkling artifact" is a color-flow sonographic artifact described behind calcifications and presenting as a random color encoding in the region where shadowing would be expected on gray-scale images. Our purpose was to study the relationship between this twinkling artifact seen behind urinary stones on color-flow sonography and the morphology or biochemical composition of these urinary stones. MATERIALS AND METHODS: Forty-seven urinary stones were studied in vitro with color-flow sonography. Transmit frequency, color gain, velocity range, color filters, focal depth, and depth of field were changed during scanning. The twinkling artifact was graded 0 when absent, 1 when present but occupying a portion of acoustic shadowing, and 2 when occupying the entire acoustic shadowing. Stones were studied under a binocular magnifying glass to characterize the surface, and infrared spectrophotometry was used to determine the chemical composition. RESULTS: Calculi of calcium oxalate dihydrate and calcium phosphate always produced a grade 1 or grade 2 twinkling artifact. Absence of artifact was noted only for calcium oxalate monohydrate and urate stones. In 100% of grade 0 calcium oxalate stones, the monohydrate compound was predominant (>93%). In 100% of grade 2 calcium oxalate stones, the dihydrate compound was predominant (>75%). For calcium oxalate stones, the surface pattern was correlated with their composition. Sensitivity and specificity for absence of artifact, as indicative of calcium oxalate monohydrate, were 60% and 83%, respectively, for all stones and 56% and 100%, respectively, only for radiopaque stones. CONCLUSION: An in vitro relationship exists between the twinkling artifact and the morphology of urinary stones. Color-flow sonography could play a role in detecting dense calcium oxalate monohydrate calculi, which in turn may help predict fragmentability.

Artifacts↗