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At least 613 records · Page 34Linked to original sources
PubMed1994

[Enzymatic determination of sodium, potassium and chloride in plasma].

The Boehringer enzymatic reagents for Na, K and Cl determination on a Hitachi 717 automatic analyser at 37 degrees C were evaluated. Except for Na, the within-run and between-run precision assays gave CV within the SFBC ranges but were higher than those of the comparison analysers: Ektachem 500 Kokak, Dimension Ars Du Pont-De-Nemours and flame photometry. The linear ranges were larger than the usual clinical results. Accuracy, estimated from human controls, was 99 to 103% for Na and K, and 105% for Cl. Comparison of plasma from 102 to 152 patients showed a good concordance for sodium with the Dimension ARS (y = 1x + 0). On the contrary, with Ektachem Kodak, differences appeared, particularly for high values (y = 0.91x + 13.6). For potassium, the concordance was good with flame photometry (y = 1x + 0.1) and Ektachem Kodak (y = 0.94x - 0.16). For chloride, comparison was satisfactory except for high values which were underestimated by the enzymatic method: Dimension ARS (y = 1.03x - 4.8), Ektachem Kodak (y = 0.91x + 9.8). The enzymatic methods were very easy to perform and can be adapted on any autoanalyser at 37 degrees C. We conclude that they are suitable for routine clinical determination. Urinary assays are currently being developed.

Autoanalysis↗
PubMed1984

Abnormalities of cone photopigments in genetic carriers of protanomaly.

Anomaloscopic color matching was performed in 57 protanomalous boys. The relative luminous efficiencies of their mothers were measured by flicker photometry to clarify the characteristics of protanomaly carriers. The sensitivity loss of protanomaly carriers in the long wave-length region had a highly significant correlation with the anomalous quotients ( AQs ) of their protanomalous sons. This correlation means that both the luminous efficiencies of the protanomaly carriers and the AQs of their sons are determined by the same "anomalous" cone pigments.

Adolescent↗
PubMed2003

Diurnality and cone photopigment polymorphism in strepsirrhines: examination of linkage in Lemur catta.

Trichromatic color vision is routine among catarrhine primates, but occurs only as a variant form of color vision in some individuals in most platyrrhine genera. This arises from a fundamental difference in the organization of X-chromosome cone opsin genes in these two lineages: catarrhines have two opsin genes specifying middle- and long-wavelength-sensitive cone pigments, while platyrrhines have only a single gene. Some female platyrrhine monkeys achieve trichromacy because of a species polymorphism that allows the possibility of different opsin gene alleles on the two X-chromosomes. Recently, a similar opsin gene polymorphism was detected in some diurnal strepsirrhines, while at the same time appearing to be absent in any nocturnal genera. The aim of this study was to assess whether cone pigment polymorphism is inevitably linked to diurnality in strepsirrhines. Cone photopigments were measured in a species usually classified as diurnal, the ring-tailed lemur (Lemur catta), using electroretinogram flicker photometry, a noninvasive electrophysiological procedure. Each of 12 animals studied was found to have the same middle-wavelength cone pigment, with peak sensitivity at about 547 nm. In conjunction with earlier results, this implies that cone pigment polymorphism is unlikely to exist in this species and that, accordingly, such variation is not a consistently predictable feature of vision in diurnal strepsirrhines.

Animals↗
PubMed1985

Determination of nitrates in milk by ion-chromatography.

A method is described for the determination of nitrates in cow milk, human milk, milk powder or milk-based infant formulae using liquid chromatography on Spheron DEAE and a direct photometric detection (205 nm). The influence of removing proteins by precipitation with Carrez reagent on the accuracy of determination was studied. The proposed method gives identical results with the reference method (photometry after reduction of nitrate to nitrite) but is more rapid. Its limit of determination is 0.5 mg NO3-/l of milk, its reproducibility is 4% (relative standard deviation).

Animals↗
PubMed1987

Kinetic description of proteolysis. Part 4. Hydrolysis kinetics of partial protein hydrolysates.

This report presents experimental data on kinetics of casein hydrolysate hydrolysis. The experiments were interpreted in the framework of a theory reported, which is guided by an experimentally measurable value--a total molar concentration of all peptides and amino acids (total amino nitrogen). The total amino nitrogen N was determined by photometry of N-trinitrophenyl (N-TNP) derivatives obtained by means of trinitrobenzenesulfonic acid (TNBS). Unlike the procedures reported previously, we stopped the proteolysis reaction by boiling, and performed the trinitrophenylation in a 20% V. aqueous solution of MeCN.

Amines↗
PubMed2003

Phorbol ester uncouples adenosine inhibition of presynaptic Ca2+ transients at hippocampal synapses.

Synaptic transmission involves Ca2+ influx at presynaptic terminals. Adenosine receptors inhibit transmission, and this effect can be abolished by activation of PKC with phorbol esters. Whether protein kinase C (PKC) acts via alterations in Ca2+ entry at the presynaptic terminal is unknown. In the present study, we recorded the presynaptic Ca2+ transients (preCa(delta)) in hippocampal stratum radiatum, using fluorescence photometry. The calcium dye Fura-2 AM was used to load the Schaffer collateral/commissural tract and its terminals. Tetrodotoxin (TTX)-sensitive Na+ channels and Cd2+-sensitive, high-voltage activated Ca2+ channels (HVACCs) were required to elicit the preCa(delta). Application of the phorbol ester phorbol-12,13-dibutyrate (PDBu) abolished the adenosine inhibition of both preCa(delta) and the field excitatory postsynaptic potentials (fEPSPs). PDBu consistently potentiated fEPSPs, and also increased preCa(delta) in a large majority of the slices examined. Regardless of whether potentiation was observed, PDBu always prevented adenosine inhibition of preCa(delta). In contrast, the inactive phorbol ester, 4alpha-phorbol, did not alter adenosine inhibition of preCa(delta), indicating that PKC activation is necessary for the occurrence of the observed effects. Our findings suggest that PKC activation abolishes adenosine's inhibitory effect on synaptic activity involving presynaptic Ca2+ entry.

Adenosine↗
PubMed2000

Lutein and zeaxanthin in the eyes, serum and diet of human subjects.

Inverse associations have been reported between the incidence of advanced, neovascular, age-related macular degeneration (AMD) and the combined lutein (L) and zeaxanthin (Z) intake in the diet, and L and Z concentration in the blood serum. We suggest that persons with high levels of L and Z in either the diet or serum would probably have, in addition, relatively high densities of these carotenoids in the macula, the so-called 'macular pigment'. Several lines of evidence point to a potential protective effect by the macular pigment against AMD. In this study we examined the relationship between dietary intake of L and Z using a food frequency questionnaire; concentration of L and Z in the serum, determined by high-performance liquid chromatography, and macular pigment optical density, obtained by flicker photometry. Nineteen subjects participated. We also analysed the serum and retinas, as autopsy samples, from 23 tissue donors in order to obtain the concentration of L and Z in these tissues. The results reveal positive, though weak, associations between dietary intake of L and Z and serum concentration of L and Z, and between serum concentration of L and Z and macular pigment density. We estimate that approximately half of the variability in the subjects' serum concentration of L and Z can be explained by their dietary intake of L and Z, and about one third of the variability in their macular pigment density can be attributed to their serum concentration of L and Z. These results, together with the reported associations between risk of AMD and dietary and serum L and Z, support the hypothesis that low concentrations of macular pigment may be associated with an increased risk of AMD.

Adolescent↗
PubMed1994

Electrophysiological measurements of spectral mechanisms in the retinas of two cervids: white-tailed deer (Odocoileus virginianus) and fallow deer (Dama dama).

Electroretinogram (ERG) flicker photometry was used to study the spectral mechanisms in the retinas of white-tailed deer (Odocoileus virginianus) and fallow deer (Dama dama). In addition to having a rod pigment with maximum sensitivity (lambda max) of about 497 nm, both species appear to have two classes of photopic receptors. They share in common a short-wavelength-sensitive cone mechanism having lambda max in the region of 450-460 nm. Each also has a cone having peak sensitivity in the middle wavelengths, but these differ slightly for the two species. In white-tailed deer the lambda max of this cone is about 537 nm; for the fallow deer the average lambda max value for this mechanism was 542 nm. Deer resemble other ungulates and many other types of mammal in having two classes of cone pigment and, thus, the requisite retinal basis for dichromatic color vision.

Animals↗
PubMed1983

An optical micromethod for the determination of relative crystallisation rates of calcium oxalate in gels: method and preliminary results.

This paper describes a new, highly efficient micromethod for the determination of relative crystallisation rates of calcium oxalate (CaOx). Crystallisation is performed in the upper layer of a gel (bactoagar, agarose) which contains one component (oxalate) of the sparingly soluble salt. Precipitation is started by pipetting Ca++ containing solutions (in the presence and absence of crystallisation inhibitors) onto the gel. The process is followed quantitatively as a function of time by means of vertical light path photometry carrying out quasi-simultaneous multideterminations within a 50-fold multicuvette. The test volume is 0.1 ml. The method is suitable for large scale determinations. About 50 single crystallisation kinetics can be measured within 5-15 min. Testing three known inhibitors of CaOx crystal formation, relative inhibitory activities were obtained with standard errors of 1%-4%.

Calcium Oxalate↗
PubMed1985

Errors due to heparin in the estimation of plasma sodium and potassium concentrations.

The effect of adding sodium heparin (5000 U/ml and 1000 U/ml) to whole blood on the concentrations of plasma sodium and potassium was examined. When the analysis was done by flame photometry both preparations of heparin caused an increase in plasma sodium concentration. If the analysis was done by a direct ion selective electrode method the 5000 U/ml heparin caused a decrease and the 1000 U/ml caused an increase in plasma sodium concentration. Plasma potassium concentration decreased when 1000 U/ml heparin was added irrespective of the method of analysis. It is recommended that sodium heparin should not be used in samples taken for estimation of sodium and potassium.

Blood Specimen Collection↗
PubMed1996

Quantitative photometrical assessment of iron deposits in synovial membranes in different joint diseases.

We investigated 86 synovial membranes from patients suffering either from rheumatoid arthritis (RA) or osteoarthritis (OA). Iron deposits in the synovial membrane were stained by the Prussian blue reaction, and the amount of stained iron was quantitatively assessed by microscope photometry. We found a statistically significant increase in iron deposits in the synovial membrane of RA patients when compared to OA patients. The amount of iron deposits correlated with the histological subtype of synovitis, those presenting with more exudative and proliferative features showing greater amounts of iron deposits. We also observed an inverse correlation between the haemoglobin concentration and erythrocytes in the serum and the amount of iron in the synovial membrane. From our data we concluded that iron deposits in the synovial membrane can contribute by several mechanisms, including activation of oxygen radicals, to the chronic inflammatory reaction in RA synovitis.

Aged↗
PubMed1991

Stride-dependent changes in gait of older people.

Infrared computerized stroboscopic photometry was used to measure the kinematic profile of walking of 20 young adults and 20 neurologically healthy elderly people. Compared with the young adults, the elderly exhibited 17-20% reductions in the velocity of gait and length of stride. The elderly also exhibited comparable reductions in the maximum toe-floor clearance, arm swing, and rotations of the hips and knees, but these alterations in gait were attributable to the reduction in stride length, which may have non-neurological causes. The influence of reduced gait velocity and stride length on the other characteristics of walking must be considered when evaluating the pattern of walking in elderly people.

Adult↗
PubMed1991

Adhesion of Candida albicans to epithelial cells effect of polyoxin D.

Data from our previous studies suggested that the fungal cell wall component, chitin, is involved in the adhesion of Candida albicans to mucosal surfaces. In the present study, we investigated the effect of polyoxin D, an inhibitor of chitin synthase, on the interaction of the fungus with epithelial cells. The effect of polyoxin D on Candida was evaluated in in vitro assays for its capacity to adhere to buccal epithelial cells (BEC), and by fluorescent-microscopy photometry and flow cytometry using cells stained with cellufluor (CF), a fluorochrome with affinity for chitin. C. albicans grown with and without polyoxin D was stained with CF and examined in a fluorescent microscope equipped with a photometer. Measurements of fluorescence revealed a wide range of intensity among C. albicans cells and a decreased intensity in polyoxin D treated cultures. Flow cytometry analyses of yeasts revealed 2 peaks of fluorescence intensity, and pointed to differences between polyoxin D treated and non-treated microorganisms. C. albicans stained with CF were separated into 2 subpopulations by flow cytometry according to fluorescence intensity. In vitro adhesion of each subpopulation to BEC was similar. Polyoxin D treated fungi showed significantly reduced adherence to BEC, as evaluated by a radioactivity assay with radiolabelled yeasts and by microscopic readings. The reduction in adhesion was Polyoxin D concentration dependent. These observations support our previous findings suggesting involvement of chitin in the attachment process of C. albicans (CBS562) to epithelial cells.

Antifungal Agents↗
PubMed1976

Method for simultaneous determination of red cell and plasma flow velocity in vitro and in vivo.

A method is described which can be used to simultaneously determine the flow velocity of plasma and of red blood cells in small glass tubes in vitro or in living microvessels of the microcirculation. The principle of dual slit photometry is applied to the measurement of plasma flow by determining the passage time of a dye bolus across two photodetectors separated by a variable distance. Measurements performed both in vitro and in vivo indicate a significant difference (up to 85%) between cellular and plasmatic flow velocity.

Animals↗
PubMed1975

Microrheology and light transmission of blood. III. The velocity of red cell aggregate formation.

The formation of primary (rouleaux) and secondary (rouleaux networks) RCA was studied by microcinematography (12 frames/sec) and photometry in a counterrotating "rheoscope" chamber. The blood was first subjected to rapid viscometric flow (460 sec-1, all RBC dispersed and aligned in flow) and then brought abruptly to full stop. In normal human blood, primary and secondary RCA occurred simultaneously, and were completed within 8 to 10 sec after stop. Blood from pregnant women at term, known for its pronounced red cell aggregation, shows a dissociation between the formation of short primary rouleaux (initiated even before full stop and completed 1-2 see thereafter) and secondary RCA completed 3-5 see after stop. RCA increases the light transmission of blood (measured by an increase in photovoltage V), the process and its first derivative (dV/dt equals I) can be recorded. After flow stop, there is an exponential decay of I(I equals t-I-o with e-lambda-t). The half time of this decay is recorded and correlated to the kinetics of red cell aggregate formation In human blood the half time of this process varies between 1.0 and 6.0 sec. In suspensions of human RBC in artificial plasmas, t-1/2 decreases with increasing concentration of fibrinogen and/or Dextran 250000, the second component appearing at concentrations above 500 mg-%. The method lend sitself for the quantification of RCA in small blood samples (20 mul).

Blood Viscosity↗
PubMed1994

Validity of the Wescor's sweat conductivity analyzer for the assessment of sweat electrolyte concentrations.

The purpose of this study was to compare the "NaCl equivalent" values determined by the Wescor's sweat conductivity analyzer (Sweat-Chek) with the sweat Na+ and Cl- concentration values measured by conventional methods. The sweat was induced by 60-min exercise and collected by a closed-pouch collector. The "NaCl equivalent" values determined by the sweat conductivity analyzer (mean: 75 mmol.L-1, range: 38 - 122, n = 72) were significantly (P < 0.05) greater than Na+ concentration values (mean: 71 mmol.L-1, range: 24 - 123, n = 72) measured by flame photometry and Cl-concentration values (mean: 61 mmol.L-1, range: 18 - 100, n = 48) measured by coulometric titration. The difference were most accentuated for low concentration values. The 95% confidence-agreement intervals around the mean differences between methods were 11 mmol.L-1 (14%) for both Na+ and Cl-. The Sweat-Chek conductivity analyzer is a portable instrument which approximates the actual Na+ and Cl- concentrations in sweat but with a positive bias probably due to the other unmeasured anions present in sweat.

Chlorides↗
PubMed1986

Effects of temperature, ouabain and diuretics on the cell sodium and potassium contents of isolated rat kidney tubules.

Cell Na+ and K+ contents were measured by flame photometry in single pieces of rat medullary thick ascending limb (MAL) and medullary collecting tubules (MCT) after an overnight incubation at various temperatures. Below 8 degrees C, MCT samples were no more able to sustain high-K+, low-Na+ cell concentrations, and sodium progressively replaced cell potassium as the temperature decreased. The loss of potassium and the accompanying accumulation of sodium by MCT cells occurred at lower or higher temperature when amiloride (20 mumol/l) or ouabain (1 mmol/l) was present respectively in the incubation medium compared to that observed on control non-treated MCT. In contrast, MAL samples maintained normal cation gradients across their membrane at all temperatures, including 0 degree C, even in the presence of ouabain. However, MAL cells lost nearly all their potassium which was replaced by sodium when they were incubated in K+-free solution. These Na+-loaded, K+-depleted MAL cells restored high-K+ and low-Na+ contents similar to those of control samples when they were further incubated for 1 h at 0 degree C in presence of 5 mmol/l external potassium. Even in the presence of 1 mmol/l ouabain and at 0 degree C, a restoration of almost normal cation gradients occurred provided that Na+-loaded MAL were incubated for 24 h after potassium addition to the external medium. The results are discussed in relation to the respective effects of low temperatures on the passive and active components of the cation balance in the cells of the two nephron segments.

Amiloride↗
PubMed1978

[Determination of diterpene glycosides in coffee (author's transl)].

The determination of 3'O-beta-D-glucopyranosyl-2'-O-isovaleroyl-2beta-(2-desoxy-atractyligenin)-beta-D-glucopyranoside (KA 1) and 2-O-beta-d-glucopyranosyl-atractyligenin (KA II) in coffee was carried out by liquid/liquid-partition, column chromatography, thin layer chromatography, and photometry. In robusta and arabusta green coffees KA I levels were below the limit of detection, in arabica green coffees between 170 and 460 mg/kg. KA II was present in robusta green coffees between 10 and 45 mg/kg, in arabusta green coffee at about 60 mg/kg, in arabica green coffees between 290 and 340 mg/kg. During roasting these values are reduced, but not during commercial extraction.

Chromatography, Liquid↗