Biomedical subjects
Publications and source records attributed to E Rovida.
Large white pig and human blood oxygen affinities are different due to different primary structures of hemoglobin. Empirical equations are reported to predict the oxygen partial pressure at half-saturation of hemoglobin (p50) from known values for pH, pCO2 and 2,3-diphosphoglycerate, with an accuracy of +/- 0.82 torr.
We describe a new polarographic method to measure the haemoglobin oxygen saturation in whole blood, employing up to 10 microliters of sample in a standard case. The measurement is done in an anaerobic stainless-steel cuvette (1 ml) recording three oxygen tension values: (1) that of an air-equilibrated buffer before the addition of the sample; (ii) that after the addition of the sample; and (iii) that after the addition of an oxidant. The haemoglobin oxygen saturation is then calculated from the three oxygen tension values, the volume of the reagents, and the solubility coefficient of oxygen. This method is simple, inexpensive and accurate, and correlates well with other standard methods.
We investigated the effect of temperature (19, 30, 37, and 43 degrees C) on the p50 value for normal human blood at pco2 = 5.72 kPa (43 mmHg), at various pHs (range 7.0 to 7.6) and molar ratios of [2,3-diphosphoglycerate]/[Hb4] (range 0.4 to 2.4). The d(log p50)/d(pH) coefficient varied from 0.39 at 19 degrees C to 0.35 at 43 degrees C. The relationship between log p50 and 1/T (T = degrees Kelvin) was linear under the experimental conditions used, and the d(log p50)/d(1/T) coefficient varied between -2138 at pH 7.0 and -2162 at pH 7.6, independent of the concentration of 2,3-diphosphoglycerate. Assuming that the effect of pco2 on the p50 value is the same at 19, 30, and 43 degrees C as at 37 degrees C, one can use the reported coefficients to calculate the p50 value for normal human blood under conditions of temperature, pH, pco2, and 2,3-diphosphoglycerate concentrations prevailing under physiological and pathological conditions. The p50 value calculated by empirical equations, taking into account the effect of temperature, correlated well with the values for p50 determined experimentally (y = 0.9774x + 0.453; r = 0.998; n = 60), with an SD of 52 Pa (0.39 mmHg).
A new automatic apparatus based on the differential measurement of pH between two solutions has been developed. Two 25-microL (internal volume) glass capillary electrodes are used to measure the results of automated (under microcomputer control) chemical reactions that lead to the liberation or the uptake of hydrogen ions. The sensitivity of the differential pH measurements is better than +/- 0.0001 pH unit, and the change in H+ concentration that can be detected by such an apparatus is 1 mumol/L for plasma and 3 mumol/L for whole blood. The technique has been applied to the measurement of glucose in plasma, giving results in agreement with the specifications of the Food and Drug Administration reference method for quantitative determination of glucose (hexokinase/glucose-6-phosphate dehydrogenase method).
Human cultured cells (EUE) were synchronized by the method of the mitotic harvest and the degree of synchronization, during the first duplication interval, determined by various tests which include growth curves, mitotic index cell-size distributions. Values of synchronization index initially greater than 90% and desynchronization rate of about 2%/hour were evaluated. The survival after 1.75 Gy of 31 MeV protons irradiation shows a sensitive period in the late G1 followed by an increase in radioresistance to a maximum in S.