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PubMed1990

Near-patient potassium and sodium measurements: evaluation of ion-selective electrodes (Ionometer EF2) in a dialysis department.

For potassium and sodium monitoring, an Ionometer EF2 was installed in our dialysis unit. The apparatus measured linearly, and between-series and within-series variations were comparable to flame photometry. No difference in performance was disclosed when operated by one or several persons. The 95% limits of agreement between Ionometer EF2 and flame photometry were for potassium -0.29 and 0.43 mmol/l and for sodium -5.0 and 2.89 mmol/l, respectively. Contrary to sodium, the accidental difference for potassium was greater than expected from analytical variation.

Adolescent↗

PubMed1984

A new method of measuring in vivo the lens transmittance, and study of lens scatter, fluorescence and transmittance.

We propose a new method to measure in vivo nuclear transmittance using scanning photometry, thus complementing its present application in measuring lens scatter and fluorescence. We compared our method of measuring the transmittance with a previously reported in vivo method and found an adequate correlation. We then measured the fluorescence, scatter and transmittance of lenses without cataract and those with as much as a mild yellowing. The three phenomena correlated with age. In addition, this study allowed a correlation of the three phenomena with each other, indicating that the loss of transmittance of the nucleus cannot be explained by its thickening alone but that changes in its composition must take place. Finally, a preliminary study on diabetics showed early onset of the process responsible for the increase in lens fluorescence. This process did not seem to be accelerated in diabetics in comparison with normals. The nuclear scatter appeared to increase more rapidly with age in nondiabetics as compared to diabetics. This preliminary study suggests mainly that scanning photometry can be used to study aging and pathologic changes in the lens.

Absorption↗

PubMed2005

A luminous efficiency function, V*(lambda), for daylight adaptation.

We propose a new luminosity function, V*(lambda), that improves upon the original CIE 1924 V(lambda) function and its modification by D. B. Judd (1951) and J. J. Vos (1978), while being consistent with a linear combination of the A. Stockman & L. T. Sharpe (2000) long-wavelength-sensitive (L) and middle-wavelength-sensitive (M) cone fundamentals. It is based on experimentally determined 25 Hz, 2 degrees diameter, heterochromatic (minimum) flicker photometric data obtained from 40 observers (35 males, 5 females) of known genotype, 22 with the serine variant L(ser180), 16 with the alanine L(ala180) variant, and 2 with both variants of the L-cone photopigment. The matches, from 425 to 675 nm in 5-nm steps, were made on a 3 log troland xenon white (correlated color temperature of 5586 K but tritanopically metameric with CIE D65 standard daylight for the Stockman and Sharpe L- and M-cone fundamentals in quantal units) adapting field of 16 degrees angular subtense, relative to a 560-nm standard. Both the reference standard and test lights were kept near flicker threshold so that, in the region of the targets, the total retinal illuminance averaged 3.19 log trolands. The advantages of the new function are as follows: it forms a consistent set with the new proposed CIE cone fundamentals (which are the Stockman & Sharpe 2000 cone fundamentals); it is based solely on flicker photometry, which is the standard method for defining luminance; it corresponds to a central 2 degrees viewing field, for which the basic laws of brightness matching are valid for flicker photometry; its composition of the serine/alanine L-cone pigment polymorphism (58:42) closely matches the reported incidence in the normal population (56:44; Stockman & Sharpe, 1999); and it specifies luminance for a reproducible, standard daylight condition. V*(lambda) is defined as 1.55L(lambda) + M(lambda), where L(lambda) and M(lambda) are the Stockman & Sharpe L- & M-cone (quantal) fundamentals. It is extrapolated to wavelengths shorter than 425 nm and longer than 675 nm using the Stockman & Sharpe cone fundamentals.

Adaptation, Physiological↗

PubMed1968

Irreversibly sickled erythrocytes: a consequence of the heterogeneous distribution of hemoglobin types in sickle-cell anemia.

THE AMOUNT OF FETAL HEMOGLOBIN (HB F) IN ERYTHROCYTES OF PATIENTS WITH SICKLE CELL ANEMIA (HB SS DISEASE) WAS MEASURED BY TWO METHODS: (a) photometry of individual cells stained for Hb F by the Kleihauer-Betke technique; and (b) chemical assay of alkali-resistant hemoglobin in cells distributed according to specific gravity by ultracentrifugation. Irreversibly sickled cells (ISC), which could be identified directly during photometry and which were found to gather in high concentration at the bottom of ultracentrifuged cell columns, contained significantly less Hb F than non-ISC. Cell content of total Hb was constant regardless of cell size, shape, or ultracentrifugal behavior: thus absolute amounts of Hb F and S varied reciprocally from cell to cell. In experiments designed to estimate age, at formation, and rate of destruction of ISC, Hb SS blood was incubated with selenomethionine-(75)Se (which labels reticulocytes) or (51)Cr (which labels erythrocytes at random) and reinfused. Sequential blood samples were separated by ultracentrifugation into fractions rich in reticulocytes, non-ISC, and ISC; and chronological changes in the specific activity of each fraction were determined. Analogous information was obtained from radioautography of sequential blood samples after reinfusion of whole blood labeled with amino acids-(3)H: this technique permitted direct visual characterization of labeled erythrocytes as ISC or non-ISC, all of which had been reticulocytes at the time of reinfusion. The transformation of non-ISC into ISC, presumably a manifestation of membrane damage, proved to begin soon after cell release from the marrow; and ISC subsequently underwent rapid removal from the circulating blood. IT IS THEREFORE APPARENT FROM THESE STUDIES THAT, IN HB SS DISEASE, RELATIVELY SMALL RECIPROCAL CHANGES IN THE AMOUNTS OF THE TWO MAJOR HEMOGLOBINS CARRY PREDICTIVE IMPORTANCE: (a) net synthesis of Hb F is least in erythroid cells destined to become ISC; and (b) these irreversibly deformed erythrocytes suffer preferential destruction.

Adult↗

PubMed1982

Luminous-efficiency functions for point sources.

Luminous-efficiency functions for small fields were measured with flicker photometry and heterochromatic brightness-matching methods for the same two subjects. For the larger stimuli (22.9 and 11.5'), the luminous-efficiency functions differed between the two methods. Those obtained by flicker photometry showed a simple narrow shape, whereas those obtained by heterochromatic brightness matching showed increased sensitivity at short and long wavelengths. The difference however, decreased as the stimulus was reduced to 2.3', and the luminous-efficiency functions converged to curves that resemble the CIE V (lambda ) or Judd's modification. It seems unnecessary to introduce a new luminous-efficiency function for point sources, which is fortunate for practical purposes.

Adult↗

PubMed1984

Spectral sensitivity and wavelength discrimination of the human peripheral visual field.

Spectral sensitivity and wavelength discrimination are determined along the nasal horizontal meridian of the human peripheral retina. The target size as a function of eccentricity is varied according to a particular cortical magnification factor. Spectral sensitivity is measured by flicker photometry parameterized for the flicker frequency (10-20 Hz) and is found to be independent of the eccentricity (0-80 degrees) for 20-Hz flicker photometry after correction of the foveal spectral sensitivity for macular pigment absorption. This 20-Hz function is chosen as being representative for the peripheral luminous-efficiency function and is used in the wavelength-discrimination experiments. The peripheral retina can perform wavelength discrimination up to an eccentricity of 80 degrees. If field-size scaling according to the eccentricity-dependent cone density, the cortical magnification factor, or the reciprocal of the interganglion cell distance is applied, then wavelength-discrimination performance from 8 degrees to 80 degrees eccentricity is roughly the same. Foveal wavelength discrimination is considerably better than peripheral wavelength discrimination.

Adult↗

PubMed2001

Spectral luminous efficiency as a function of age.

Spectral luminous efficiency function for a 2-deg field at a photopic level (100 Td) was measured for 91 observers by flicker photometry (FP) and for 97 observers by direct brightness matching (DBM), to find age-related change in the efficiency function as well as to obtain a reliable data set to be used in photometry. Observers ranged in age from 11 to 78 years. A gradual reduction of luminous efficiency with age was observed for both functions by FP and by DBM in the short-wave region, which was expected because of the age-related increase of optical density of eye lens. A similar age-related reduction of efficiency was observed in the long-wave region for the function obtained by DBM; this reduction was regarded as being due to reduced chromatic contribution to brightness with age. Principal components analysis on the spectral efficiency data and an analysis of the efficiency difference between the data obtained by DBM and FP confirmed this conclusion. Assuming a log-linear change in efficiency with age for any wavelength throughout the life span, spectral luminous efficiency function at any age was derived for photometric use.

Adolescent↗

PubMed2004

Assessment of potassium and sodium ion concentrations in the vitreous humour of swine isolated eyeballs after organism death.

Potassium and sodium ion concentrations were estimated by the flame photometry and potentiometry in the vitreous fluid of isolated porcine eyeballs at time of death and of eyeballs, stored at temperature of 6-8 degrees C during post-mortem intervals: 4, 28, 52, 75, 100, 124 and 148 hours. The increase of K+ concentration and decrease of Na+ concentration were proportional to the increasing post-mortem time intervals. The results of the potentiometric measurements of K+ and sodium ion concentrations were significantly lower, as compared to those after flame photometry. In all the vitreous fluid smears after 124 and 148 hours, gram (-) bacteria were found. Our results suggest that bacterial infection participates in the variability of K+ levels. The influence of bacterial infection on the margin of error for the K+ post-mortem test remains unanswered and needs further studies.

Animals↗

PubMed1992

Method-dependent differences in apparent sodium concentrations in plasma after exchange transfusions with citrated blood.

Shortly after exchange transfusions (n = 7) with citrate-dextrose-phosphate (CDP)-treated blood, but not after regular transfusions (n = 9), sodium concentrations in plasma were significantly and paradoxically lower (3-10 mmol/L) by Ektachem 700 XR determination [with use of electrolyte reference fluid (ERF) generation 00] than by flame photometry. Similar between-method differences could also be generated by in vitro supplementation of plasma pools with CDP solution, with trisodium citrate, or to a lesser extent with Na2HPO4. For four potentiometric methods the analytical recovery of sodium added as CDP was significantly lower than by flame photometry. Within each potentiometric method the recovery was also less than the value for sodium added as NaCl. A significant association of sodium ions with citrate3- ions and, to a lesser extent, HPO4(2-) ions could theoretically account for at least part of the observations, conferring greater medical relevance to potentiometric measurements in this particular clinical situation.

Citrates↗

PubMed1991

[Evaluation of enzymatic methods for the determination of plasma sodium and potassium using the Hitachi 747 analytic system].

In the hospital clinical laboratory, plasma potassium and sodium are usually determined by using a flame photometer or ion-selective electrodes, for which special equipment is required. The new enzymatic methods of sodium and potassium can be used as a routine chemical method. We evaluated the new enzymatic methods for the determination of sodium and potassium in human plasma on the Hitachi 747. The sodium and potassium assay kits were purchased from Boehringer Mannheim, Germany. Precision studies were performed using three levels of pool plasma. The coefficients of variation (CV) of sodium and potassium determination were less than 1.0% and less than 2.2% by intraassay and interassay respectively. The recoveries of the assigned values of the ten control sera were 97-102%. Comparisons with results either from flame photometry and from ion-selective electrodes showed no clinically relevant differences for 100 patient samples. Performance of the enzymatic methods for Na+ and K+ is clinically comparable to flame photometry or ion-selective electrodes in the routine clinical chemistry laboratory.

Clinical Enzyme Tests↗

PubMed1989

[A method of studying the aggregative function of thrombocytes].

Platelet aggregation function has been examined by photometry; the procedure is as follows: the blood plasma enriched for platelets is stirred and stabilized in a not full photometer cuvette rotating with a 40-60 r.p.m. speed in a plane perpendicular to the luminous flux. The air hole in the cuvette provides the plasma stirring atraumatic for platelets, whereas the cuvette rotation rules out sedimentation of the blood platelets and their aggregants. Studies of the platelet aggregation in 18 normal subjects and 18 coronary patients have shown that such technique improves the accuracy and sensitivity of blood platelet aggregation photometry.

Coronary Disease↗

PubMed1989

Quantitative immunohistochemistry: standardization and possible application in research and surgical pathology.

We describe three different methods of calibration of quantitative immunohistochemistry, two of them based on self-made dye-agarose or antigen-agarose substrates. Quantification of immunostained objects (immunosignals) can be done by (1) microscope photometry (plug method) or scanning-photometry; (2) and densitometry of a television transformed microscope image. Both approaches are subjected to the different methods of calibration and three examples of application.

Arginase↗

PubMed1988

Enzymatic determination of sodium in serum.

This is a kinetic assay for measuring serum Na+ concentration based on determination of Na+-dependent beta-galactosidase (EC 3.2.1.23) activity. The method, sufficiently sensitive to measure sub-millimolar concentrations of Na+, was modified by including a Na+-binding agent (cryptand) to provide a linear assay for serum Na+ concentrations between 110 and 160 mmol/L. The assay was developed with and evaluated in the Cobas Fara centrifugal analyzer (and has been used in other kinetic analyzers). Within-run and between-run CVs were less than 1%. The reaction rate for normal serum samples (0.20 delta A/min) is about 10-fold that of the reagent blank. Results correlated well with flame photometry. Interference from bilirubin, hemoglobin, lipemia, heparin, and other cations was negligible. The method offers a practical alternative to the use of ion-selective electrodes and flame photometry for measuring serum Na+ in high-throughput or "stat" biochemical analyzers.

Bridged Bicyclo Compounds↗

PubMed1988

Lithium determined in serum with an ion-selective electrode.

We evaluated the performance of the lithium ion-selective electrode (ISE) in the Du Pont Na/K/Li analyzer. Lithium concentrations in 106 serum samples from patients being treated with lithium were measured in duplicate with the ISE and by flame photometry. The slope of the regression line for the two methods was 1.004 with a standard error of the estimate of 0.049 mmol/L (x = flame photometry, y = ISE). Lithium measurements by the ISE method in serum or aqueous standards were linear to greater than 2.0 mmol/L. Within-run CVs for low (0.31 mmol/L) and high (1.15 mmol/L) lithium controls were 5.9% and 1.7%, respectively (n = 20). Day-to-day CVs for the same controls were 9.8% and 3.3%, respectively (n = 20). There was no significant interference when the concentrations of sodium, potassium, calcium, or magnesium were varied, nor did intervening urinary lithium analyses affect the measurement of serum lithium. Results for lithium measurement in four serum-based survey materials compared well with results by isotope dilution/mass spectrometry.

Electrodes↗

PubMed1987

[Patient-adapted, ion selective analysis--characteristics of a new instrument].

We report on a newly developed instrument with ion-selective electrodes (IONOMETER EF) for the measurement of sodium, potassium and calcium. The measurements in whole blood and plasma from intensive care patients were compared with flame photometry. We assessed the precision and accuracy of these measurements. The precision of the analysis is excellent: K+ 4.69 +/- 0.03 mmol/l; Na+ 139.2 +/- 0.27 mmol/l; Ca++: 1.23 +/- 0.03 mmol/l. When assessing the accuracy, the characteristics of the ionselective device have to be considered, as well as differences in solvent volumes, when compared with flame photometry. The correlation coefficient of potentiometric analyses of whole blood and plasma is r = 0.99. It seems to be appropriate to define new normal ranges for ionselective electrode systems.

Blood Chemical Analysis↗

PubMed1981

Stability of sodium and potassium in lyophilized quality control serum. A study of data from the Quality Assurance Service Program of the College of American Pathologists.

The long-term prereconstitution stability of sodium and potassium in large pools of lyophilized quality control serum used in Regional Quality Control Programs, conducted between 1977 and 1980 is reviewed. In approximately one third of 27 pools studied, minimal but significant increases in sodium concentration were detected, these increases averaged less than 0.50 per year and confirmed our previously reported results from pools analyzed between 1973 and 1976. Results relating to potassium stability have been inconsistent. The previously reported tendency for potassium to increase in some pools was again suggested by data obtained from laboratories using automated flame-emission photometry procedures. This was not confirmed, however, by the data reflecting manual/semi-automated flame-emission photometry procedures or automated electrode methods. It is postulated, that the source of sodium causing the increases in concentration is the glass containers in which control materials are stored between the time of manufacture and reconstitution. Regression analysis against time of monthly interlaboratory means, from participants in Regional Quality Control Programs, is a useful tool for evaluating postmanufacture stability of analytes in pools used for daily internal quality control procedures.

Blood Preservation↗

PubMed1996

Comparison of methods for sodium and potassium determination in llama urine.

OBJECTIVE: To compare results for sodium and potassium determination on llama urine, using flame emission spectrophotometry (flame photometry), atomic absorption spectrophotometry (AAS), indirect ion-selective electrode potentiometry (ISE), and direct ISE. DESIGN: Llama urine samples encompassing a wide range of electrolyte concentrations were analyzed for sodium and potassium concentrations, using 4 analytical methods, and results were compared statistically to assess correlation, bias, and potential interferents. SAMPLE POPULATION: 10 healthy male llamas. PROCEDURE: Urine specimens were obtained from llamas fitted with urine collection apparatus at defined intervals over a 24-hour period. Urine samples were centrifuged, and supernatants were frozen at -70 C until analysis. Analytical procedures were done, using standard laboratory protocols. Means, correlation coefficients, and bias were calculated, and differences were evaluated by ANOVA, with significance set at P < 0.05. RESULTS: There was strong correlation and good agreement among sodium values obtained by flame photometry, AAS, and indirect ISE. Sodium values obtained by use of direct ISE correlated poorly with other methods; urine is not an acceptable specimen for this method. Only AAS and indirect ISE had good correlation (r > 0.9) for potassium values. Data did not suggest presence of a potassium chelator in llama urine; urine potassium values measured by indirect ISE were significantly higher (by 150 to 200 mmol/L) than those measured by other methods. CLINICAL RELEVANCE: Urine electrolyte analysis in llamas resulted in less agreement between methods than is generally found for serum. Data collection for patient monitoring or research analysis should be restricted to a single method to avoid differences in results attributable to analytical variance.

Analysis of Variance↗

PubMedDate not supplied

[Application of ion-selective electrodes for determining ion concentration in blood of irradiated rabbits].

Concentration of potassium and sodium ions as well as chlorides in rabbit blood serum was determined by applying the direct potentiometric method using the ion-selective electrodes. The techniques on calibration of the applied ion-selective electrodes are described and comparative data are presented of determining the concentration of potassium and sodium by the potentiometric method and that of flame photometry and of chlorides by the potentiometric and chemical methods. By high-specific ion-selective electrodes (glass for Na+, membrane one for Cl- and valinemycinic for R+) the character of ionic disturbances is established in the blood serum of rabbits irradiated with a dose of 2000 R. The concentration of potassium ions decreases 15-18 degrees min after irradiation. The concentration of sodium ions and chlorides is not changed noticeably. The concentration of calcium determined by the method of flame photometry decreases after irradiation within a range of 30 min-72h. The found changes may be explained by the damaging effect of radiation on the structure and function of the cell membranes.

Animals↗