The effect of different blood sampling sites and analyses on the relationship~ between exercise intensity and 4.0 mmol ·1? blood lactate concentration

The aim of the study was to examine whether the difference in lactate concentration in different blood fractions is of practical importance when using blood lactate as a test variable of aerobic endurance capacity. Ten male firefighters performed submaximally graded exercise on a cycle ergometer for 20-25 min. Venous and capillary blood samples were taken every 5 min for determination of haematocrit and lactate concentrations in plasma, venous and capillary blood. At the same time, expired air was collected in Douglas bags for determination of the oxygen consumption. A lactate concentration of 4.0 mmol.l-1 was used as the reference value to compare the oxygen consumption and exercise intensity when different types of blood specimen and sampling sites were used for lactate analysis. At this concentration the exercise intensity was 17% lower (P less than 0.01) when plasma lactate was compared to venous blood lactate, and 12% lower (P less than 0.05) when capillary blood lactate was used. Similar discrepancies were seen in oxygen consumption. The results illustrated the importance of standardizing sampling and handling of blood specimens for lactate determination to enable direct comparisons to be made among results obtained in different studies.     

A low cost apparatus for the automatic determination of precise oxygen equilibrium curves on red blood cell suspensions

An apparatus for the automatic recording of precise oxygen equilibrium curves on red cell suspensions, as well as on hemoglobin solutions, is described. Dual wavelength determination of fractional oxygen saturation is used, eliminating noise for turbid samples and very small blood samples are needed. An example of data is given for trout blood.     

Use of spin probe in the determination of oxygen consumption in human neutrophils

A quantitative method of the oxygen consumption rate measurement by human blood neutrophils upon their activation is described. This method is based on the spin exchange determination between 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-1-yloxyl spin probe and oxygen molecules from the ESR spectra. Method allows the determination of about 1 micromolar concentrations of oxygen.     

Respiratory activity of avian blood cells

The respiratory activity of avian blood cells was determined with samples of whole blood from individual male and female chickens. this oxygen consumption represents only that of the cells since no measurable activity was found in the plasma samples. the precision of determining respiratory activity was examined statistically and found to be approximately that obtained with a blood cell count but much less precise than the packed cell volume determination. the variability of cell count and mean corpuscular volume indicates that neither is a good means for expressing oxygen consumption – the most meaningful basis is oxygen consumption per milliliter of cells. the relationship between blood cell respiration and temperature is described.     

Mitochondria and FOXO3 in stem cell homeostasis,a window into hematopoietic stem cell fate determination

The production of all blood cells from hematopoietic stem cells (HSC) is highly sensitive to reactive oxygen species (ROS). Cumulating evidence suggests that mitochondria are critical for HSC fate determination. FOXO are known regulators of anti-oxidant response and key to the maintenance of HSC. Recent works indicate that FOXO3 is implicated in the control of mitochondrial function beyond regulating levels of ROS in HSC. Here we review these findings and discuss implications for homeostatic blood formation and stem cell fate determination.     

Sickle cell anemia and the affinity of the blood for oxygen]

Blood affinity for oxygen is reduced in patients with homozygous HbS disease. The mechanisms were related to polymerisation and sickling process. In the HbS blood, P50 values were related to the percentage of sickling, the effect of prior deoxygenation on P50 measurement was established. This work underlines the influences of experimental conditions on the determination of sickle cell blood affinity and the difficulties inherent in the evaluation of in vivo oxygen transport in sickle cell disease.     

A theoretical prediction of the normal cardiac oxygen consumption

A model is described from which the entropy production associated with the process of transporting oxygen and carbon dioxide between the lungs and the muscles of the body can be calculated. The two entropy sources which are assumed to be the dominant ones for this process are the entropy production associated with the metabolism of the heart and the entropy production associated with the diffusion of oxygen and carbon dioxide into and out of the blood. The hypothesis that the observed blood flow is the one for which a given amount of oxygen and carbon dioxide is transported between the lungs and the muscles with minimum total entropy production is used to predict the value of the slope of the cardiac oxygen consumption vs. blood flow curve. At a blood flow of 15 liters/min, the predicted value of the slope of this curve is 1.2 ml/liter.     

Radiation injury in mouse lung: dependence on oxygen levels in the inspired gas

The relationship between radiosensitivity and the partial pressure of oxygen (PO2) in the inspired gas has been established for radiation pneumonitis as a measure of lung damage following irradiation of the mouse thorax. The radiosensitivity at low PO2 (0-1 per cent) fitted the linear transformation of the Alper, Howard-Flanders relationship giving a K value for lung tissue of 1.35 per cent oxygen with an oxygen enhancement ratio, m, of 2.13. The radiosensitivity at higher PO2 (5-21 per cent) did not fit the Alper, Howard-Flanders relationship probably because the PO2 of the inspired gas was greater than the PO2 in the alveolus. At the low PO2 levels in the inspired gas, back diffusion of oxygen from blood into the alveolus may lead to errors in the estimated value of K. If the low value of m is due to this 'contaminating' oxygen from blood then by taking a higher value for m, the amount of contaminating oxygen can be calculated (0.23 per cent) and a 'true' value for K(1.1 per cent) determined. Other uncertainties in this estimate of K due to the radiolytic consumption of oxygen and possible inadequacies in equilibration are discussed. Allowing for the uncertainties, it is concluded that the K value for lung damage lies towards the upper end of the range of K values measured for cells in vitro.     

Polarographic Determination of Respiratory Activity with Clark Oxygen Electrode

The authors have developed a polarographic technique in which Clark oxygen electrode (stationary platinum electrode covered with a polyethylene membrane) is employed for the determination of respiratory activity. The procedure of the operation is very simple, yet it was highly sensitive to the changes of the oxygen concentration in the solution, and the value of current was proportional to the oxygen concentration. The respiratory activity and control of rat liver mitochondria could be determined satisfactorily by this method.     

Fully reversible optical biosensors for uric acid using oxygen transduction

An optical biosensor is presented for continuous determination of uric acid. The scheme is based on the measurement of the consumption of oxygen during the oxidation of uric acid that is catalyzed by the enzyme uricase. The enzyme is immobilized in a polyurethane hydrogel next to a metal-organic probe whose fluorescence is quenched by oxygen. The consumption of oxygen was followed by measurement of changes of luminescence intensity of two kind of probes and can be related to the concentration of uric acid. Analytical ranges (0-2mM), the response times (80-100s), reproducibility, and long-term stability were investigated. The biosensors are stable for at least 1 month and are not interfered by common interferents. One kind of biosensor was applied to the determination of uric acid in human blood serum. The results agree with those of a commercial colorimetric detection kit.     

Blood sugar as an indicator of stress in the freshwater fish, Labeo capensis (Smith)

Factors involved in the determination of the blood sugar level of L. capensis have been studied. The stress of capture and transportation produces a marked increase in the blood sugar concentration. The relationship between blood sugar concentration and oxygen saturation of water and between blood sugar concentration and ammonium ion concentration was also investigated. Increases in ammonium ion concentration and decreases in oxygen saturation of water produce increases in the blood sugar concentration. The results are discussed in relation to the phenomenon of 'asphyxiation hyper-glycemia'.     

Blood rheology and oxygen uptake

Continuously measured oxygen uptake during constant work exercise (15' 50W) reveals increasing oxygen consumption in individuals with elevated blood viscosity parameters, indicating persistent contribution of anaerobic glycolysis during steady state exercise far below expected "anaerobic threshold". Improvement of viscosity parameters by prostaglandin E1--infusion (Prostavasin) 40 micrograms i.v., naftidrofurylhydrogenoxalat (Dusodril pi) 400 mg i.v. or hemodilution with 500 ml 6% hydroxyethylamylum MW 40000 (Onkohaes) in 5 patients results in significant reduction of this oxygen gradient in subsequent exercise test. Integrated VO2 during exercise above the mean value at rest or the quotient of VO2 during 15 min by VO2 during 30 min (including recovery time) are not differing significantly due to high variations inter- and intraindividually. Oxygen gradient during submaximal constant exercise permits direct clinical determination of microcirculatory performance in involved muscle tissue as a function of blood viscosity.     

Determination of oxygen saturation and hematocrit of flowing human blood using two different spectrally resolving sensors.

The blood parameters oxygen saturation and hematocrit were determined by two different spectral sensors using reflectance spectra from 550 to 900 nm and partial transmission spectra centered at 660 nm. The spectra were analyzed by the method of partial least squares. One sensor consists of a miniature integrating sphere, while the other was fiber-guided. The results show that the geometry of the sensors and different blood flows do not influence the spectral analysis significantly. Independent of the sensor geometry, both hematocrit and oxygen saturation could be determined with an absolute predicted root mean square error of less than 3%. Furthermore, the analysis showed that hematocrit prediction requires eight wavelength regions and oxygen saturation prediction requires four wavelength regions using reflectance spectroscopy. This implies that if the measurement is restricted to reflectance, a spectrometer is indispensable for determining both blood parameters. Hematocrit determination could be improved using reflectance measurements in combination with transmission.     

Measurement technique for the determination of blood oxygen saturation

A new optical measurement technique based on spectral scanning is described for the determination of oxygen saturation of whole blood. The principles of this technique are outlined, together with a calibration procedure used to test its feasibility in vitro. The preliminary results show that the accuracy of the new technique is of the order ± 2% over the full range of oxygen saturation. This degree of accuracy is comparable with commercial CO-oximeters.     

The Quantitative Determination of Fibrinogen in Normal Bovine Plasma and in Cows with Inflammatory Conditions

The quantitative determination of fibrinogen in normal plasma and in cows with inflammatory conditions. A rapid method for the quantitative determination of fibrinogen in bovine plasma is described. The method was employed in the determination of normal values in a material consisting of 100 cows and 50 calves and young animals of various ages. The mean value of the groups of cows was approximately 0.550 g/100 ml. For young animals it was somewhat lower and for cows in the last month of gestation moderately higher than in the other groups. The last part of the experiment involves the determination of the fibrinogen and γ-globulin levels in the plasma of 28 hospitalized cows with various inflammatory conditions. Group A in the material contained animals which were clinically cured and Group B animals that died or were killed. Both groups showed a considerable increase in the fibrinogen level. In Group A the mean value fell back to approximately the normal range while in Group B it remained constantly elevated. The sedimentation rate, SR, in human blood is primarily influenced by the fibrinogen content of the plasma. The SR in bovine blood is very low, and the test is therefore of little significance in diagnostic work. In conclusion, the possibility of using the fibrinogen determination in cattle for the same purpose as the SR in human blood is discussed.     

CARDIORESPIRATORY FUNCTION

Accurate evaluation of the degree of impairment of pulmonary function in persons with fibrosis and emphysema requires: (1) ventilatory measurements from rapid spirogram tracings (vital capacity, maximal breathing capacity and the time required to blow the air from the lungs); (2) determination of the degree of bronchospasm present; (3) determination of the degree of pulmonary emphysema (residual air expressed quantitatively as percent of total lung volume); (4) determination of the arterial blood oxygen saturation at rest and immediately after step-up exercise; (5) measurement of the oxygen extraction from inspired air (per cent of oxygen removed) during rest and exercise; (6) determination of the oxygen up-take during exercise; and (7) observation of the duration of dyspnea after step-up exercise.No single physiologic test is adequate in evaluating impairment of pulmonary function, and roentgenograms of the chest are unreliable as a sole basis for appraisal of disability.In industrial medicine, pulmonary function studies make possible (a) more accurate diagnosis and evaluation of pulmonary disability; and (b) earlier detection and thus prevention of prolonged exposure by susceptible individuals to environmental hazards.     

Cardiorespiratory function

ACCURATE EVALUATION OF THE DEGREE OF IMPAIRMENT OF PULMONARY FUNCTION IN PERSONS WITH FIBROSIS AND EMPHYSEMA REQUIRES: (1) ventilatory measurements from rapid spirogram tracings (vital capacity, maximal breathing capacity and the time required to blow the air from the lungs); (2) determination of the degree of bronchospasm present; (3) determination of the degree of pulmonary emphysema (residual air expressed quantitatively as percent of total lung volume); (4) determination of the arterial blood oxygen saturation at rest and immediately after step-up exercise; (5) measurement of the oxygen extraction from inspired air (per cent of oxygen removed) during rest and exercise; (6) determination of the oxygen up-take during exercise; and (7) observation of the duration of dyspnea after step-up exercise. No single physiologic test is adequate in evaluating impairment of pulmonary function, and roentgenograms of the chest are unreliable as a sole basis for appraisal of disability. In industrial medicine, pulmonary function studies make possible (a) more accurate diagnosis and evaluation of pulmonary disability; and (b) earlier detection and thus prevention of prolonged exposure by susceptible individuals to environmental hazards.     

Use of agar diffusion method for separate determination of concentration of streptomycin and rifampicin in the blood in the presence of isoniazid

Conditions for determination of streptomycin and rifampicin in the blood serum on their combined use, as well as in the presence of isoniazid are described. For determination of the blood levels of streptomycin administered in combination with rifampicin it is recommended tat a variant of Bac. mycoides 537 resistant to rifampicin be used. When the rifampicin levels are determined in undiluted serum, the value obtained should be multiplied by 1.4. When a 2-fold dilution of the serum is used, the value is multiplied by 1.15. This provides an indicator maximally close to the real content of the antibiotic in the blood serum.     

Use of a modified oxygen microelectrode and laser-Doppler flowmetry to monitor changes in oxygen tension and microcirculation in a flap

Flap failure is a clinical problem in free tissue transfer, and there is no reliable device for monitoring the tissue. Differentiating between an arterial occlusion and venous congestion is also a problem. A study was undertaken to monitor viability in a pedicled groin flap and to compare two different monitoring methods. The oxygen tension in the flap, measured with a modified Clark-type microelectrode (tip diameter = 3 to 8 microm; 90 percent response within 2.6 +/- 0.5 seconds), was compared with changes in blood flow in the flap, measured with a laser-Doppler probe. In 11 Sprague-Dawley rats, the changes in oxygen tension and blood flow in the pedicled groin flap were studied after clamping and subsequent reperfusion of the artery or vein. After occlusion of the artery to the flap, oxygen tension decreased to a stable value (i.e., the recording level remained unchanged for 30 seconds), from 19.7 +/- 1.8 to 0.3 +/- 0.1 mmHg, after 193 +/-25 seconds; blood flow decreased to a stable value, from 117 +/- 21 to 54 +/- 18 perfusion units, after 26 +/- 6 seconds. Clamping of the vein resulted in a decrease in oxygen tension, from 17.1 +/- 1.8 to 1.4 +/- 0.7 mmHg, after 416 +/- 67 seconds, and blood flow decreased to a stable value, from 90 +/- 14 to 35 +/- 6 perfusion units, after 107 +/- 27 seconds. The results of this study show that there is a difference in oxygen tension and blood flow responses between arterial and venous occlusion and that it may be possible with both methods to distinguish arterial from venous occlusion. However, although oxygen tension measurements are slightly slower in response than laser-Doppler measurements, the values are more reliable as a diagnostic tool for interpretation of a vessel occlusion.