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PubMed1994

Corneosurfametry: a predictive assessment of the interaction of personal-care cleansing products with human stratum corneum.

OBJECTIVE: Corneosurfametry is introduced as a noninvasive quantitative test rating the interaction between surfactants and human stratum corneum. It may be used as a predictive irritancy test. BACKGROUND: Surfactants present in personal-care products elicit multiple effects on the stratum corneum. With upcoming regulations avoiding animal experiments and ethical considerations for human testing, there is a need for new in vitro methods evaluating irritancy. DESIGN: Corneosurfametry entails collection of cyanoacrylate skin surface strippings and short contact time with surfactants followed by staining samples with toluidine blue and basic fuchsin dyes. Measurements are made by reading the color of samples using reflectance colorimetry. RESULTS: The intensity of color increases with irritancy potential of the surfactant. Results are reproducible, and great differences are noted among a series of diluted shampoos, shower gels and facial cleansing gels. CONCLUSION: Corneosurfametry is proposed as a rapid in vitro method allowing a predictive grading of surfactants related to irritancy.

Adult↗
PubMed1977

Effect of succinimide on hyperoxaluria in the rat estimated value of the different dosing methods of oxaluria.

In the female rat intoxicated with ethylene glycol the oxaluria increases with the degree of intoxication. The increase is less in the animals treated with succinimide. The comparative study of the results of the dosages made with gas-liquid-chromatography and by various colorimetric methods show that this later gives varying results and underestimates high concentrations of oxalic acid. The result is that any study based on results of dosages of urinary oxalic acid made by colorimetry must be taken with some reserve, and this on whether the oxalic lithiasis is experimentally induced or human, or whether its evolution is spontaneous or influenced by a therapeutic.

Animals↗
PubMed1997

Composition of human thrombus assessed by quantitative colorimetric angioscopic analysis.

BACKGROUND: Angioscopy surpasses other diagnostic tools, such as angiography and intravascular ultrasound, in detecting arterial thrombus. This capability arises in part from the unique ability of angioscopy to assess true color during imaging. In practice, hardware-induced chromatic distortions and the subjectivity of human color perception substantially limit the theoretic potential of angioscopic color. We used a novel application of tristimulus colorimetry to quantify thrombus color to both aid in its detection and assess its composition. METHODS AND RESULTS: A series of human thrombus models were constructed in vitro. Spatial homogeneity was ensured by light and electron microscopy. Quantitative colorimetric angioscopic analysis demonstrated excellent measurement reproducibility (mean difference, 0.07% to 0.17%), unaffected by illuminating light intensity (coefficient of variation, 0.21% to 3.67%). Colorimetric parameters C1 and C2 were strongly correlated (r=.99, P<.0001) with thrombus erythrocyte concentration. Principal components analysis transformed these parameters into a single value, the thrombus erythrocyte index, with little (0.06%) loss of content. Measured and predicted concentrations were similar (mean difference, 0.16 erythrocytes per 1 ng). Randomly ordered images were also subjected to visual analysis by three experienced angioscopists, with suboptimal levels of both intraobserver (mean kappa=0.63) and interobserver (mean kappa=0.48) agreement. In addition, visual ranking resulted in a Kendall rank coefficient of 0.72 to 0.76 versus a perfect 1.00 from quantitative measurement. CONCLUSIONS: Quantitative colorimetric angioscopic analysis provides a new, objective, and reproducible analytic tool for assessing angioscopic images of human thrombus. Even under ideal circumstances, experienced angioscopists do a poor job of assessing color (and therefore composition) of human thrombi. This technique can, for the first time, provide quantitative information of thrombus composition during routine diagnostic imaging.

Angioscopy↗
PubMed2000

Oximetric and capnometric studies--aspects of natural and artificial ventilation.

Methods and instrumentation of own design and their application to the measurement of oxygen and CO2 content in blood and respiration gases are discussed. Spectrophotometry, particularly double wavelength colorimetry using red light and IR light, applied to the measurement of oxygen blood saturation for in vitro examination and through an intravascular catheter for invasive in vivo study and by means of pulse oximetry for non-invasive in vivo examination are presented. The electrochemical methods applied to in vitro and in vivo measurement of oxygen in blood (amperometric method) and in respiration gases (amperometric and fuel cell methods) are discussed. The electrochemical Stow-Severinghaus method of CO2 tension measurement in blood and CO2 partial pressure in respiratory gases as well as the selective IR light (4.26 microm) absorption method and instruments of own design for CO2 measurements in respiratory gases are also discussed. The methods and instrumentation described are very important for monitoring respiratory and circulatory function, particularly during artificial ventilation and circulatory support.

Biosensing Techniques↗
PubMed1994

Biomaterials with permanent hydrophilic surfaces and low protein adsorption properties.

Low protein adsorbing polymer films have been prepared with which to fabricate intravenous containers, designed for compatibility with low concentrations of protein drugs. The material is economically manufactured utilizing physical melt blending of water-soluble surface-modifying polymers (PEO, PEOX, PVA, and PNVP) with a base polymer (EVA, PP, PETG, PMMA, SB, and nylon). Permanency of the hydrophilic surfaces so generated was confirmed by surface contact angle experiments and total organic carbon leachables analysis of the aqueous contacting solutions. Binding of IgG, albumin and insulin was studied. A sixfold reduction of protein adsorption was obtained by adding 5% PVA13K to EVA, for IgG at a bulk concentration of 2.5 ppm. Surface bound protein measured by micro-BCA colorimetry, agreed with the solution protein lost, as determined by the Fluoraldehyde procedure. Imaging of the protein exposed plastic surfaces by silver enhanced protein conjugated gold staining agreed with the quantitative assay determinations.

Adsorption↗
PubMed1982

Evaluation of a simple colorimetric assay for serum angiotensin-converting enzyme: comparison with a new ion-pair liquid chromatography-assisted assay.

The development and validation of two different assays for serum angiotensin-converting enzyme are reported. The first step in both analytical systems is based on enzymatic cleavage of the synthetic substrate, hippuryl-histidyl-leucine, under conditions advocated by Cushman and Cheung. The hippuric acid released is then assayed either by colorimetry following an azlactone condensation reaction with an aromatic aldehyde, or by reversed-phase ion-pair high-performance liquid chromatography (HPLC). Both procedures reveal good linearity in the range 0-80 nmol/ml per min, with an inter-assay coefficient of variation of 6.2% for the colorimetric assay and 4.5% for the HPLC-assisted assay. Recovery values measured for the colorimetric method ranged from 97% to 102% and for the HPLC-assisted method from 98% to 101%. The colorimetric method is suitable for performance in small hospital laboratories since it can be carried out with simple analytical instrumentation. It is obvious nevertheless, that the HPLC-assisted assay reveals better validation criteria. The method is also simple and rapid and it has successfully been used in our laboratory for the last two years.

Chromatography, High Pressure Liquid↗
PubMed1984

Colorimetric assay for N-acetyl-beta-D-glucosaminidase (NAG) in pathological urine using the omega-nitrostyryl substrate: the development of a kit and the comparison of manual procedure with the automated fluorimetric method.

This paper describes a comparison of the recently developed substrate 2-methoxy-4-(2'-nitrovinyl)-phenyl-2-acetamido-2-deoxy-beta-D-gluc opyranoside (MNP-GlcNAc) and the corresponding 4-methylumbelliferyl substrate (4-MU-GlcNAc) for the determination of urinary NAG. A good correlation (r = 0.977) was found between NAG activities in 366 urine samples from renal transplant patients determined by either the fluorimetric method or the colorimetric procedure. The colorimetric method may be used with confidence as an alternative to the fluorimetric assay and does have the advantage that colorimetry is widely used in clinical chemistry laboratories. Sample blanks are not normally required unless there is blood contamination in the urine which can easily be identified visually. The incorporation of the MNP-GlcNAc substrate into a kit suitable for the assay of urinary NAG using a simple battery-operated miniphotometer is also described. The presence of elevated NAG levels in urine can be detected rapidly and this procedure is suitable for routine monitoring of renal patients in the laboratory and may prove to be suitable for use by non-laboratory personnel in clinics or on the ward.

Acetylglucosamine↗
PubMed1993

A novel colorimetric method for determination of glycated protein based on 2-keto-glucose release with hydrazine.

We tried to measure glycated proteins by a novel method based on colorimetry of 2-keto-glucose which is released from the glycated protein (ketoamine) on heating with hydrazine. Reaction conditions were optimized with glycated human serum albumin (glc HSA) as a model compound. Ketoamine reacted quantitatively with hydrazine on heating at 100 degrees C for 0.5 h, followed by heating with phenylhydrazine at 60 degrees C for 1 h. Glucose interference with the assay was eliminated by preincubation of the sample with glucose oxidase at 37 degrees C for 0.5 h. Time courses for the coloration of glc HSA and human serum showed a profile similar to that of N-p-tolyl-D-isoglucosamine under optimized reaction conditions. The lower limit for the assay of glc HSA was 0.7 microM. The serum level of glycated proteins measured by the present method correlated well with that (fructoamine value, microM) measured by the conventional method (nitroblue tetrazolium-reducing method) (r = 0.92, n = 35). In conclusion, the present method is a novel, highly sensitive and reliable one for measuring glycated proteins in biological samples.

Colorimetry↗
PubMed1995

Estimation of bloodstain age by rapid determinations of oxyhemoglobin by use of oxygen electrode and total hemoglobin.

Bloodstain age could be estimated from the ratio of oxyhemoglobin/total hemoglobin (fractional oxyhemoglobin) in the bloodstain by this present method, if the temperature at which the bloodstain had been kept was known. The oxyhemoglobin was determined with an oxygen electrode immersed in water in which the oxygen had been depleted, and the total hemoglobin was determined by conventional colorimetry (cyanomethemoglobin method). Ages of prepared bloodstain samples (within 24 h after bleeding) were estimated by this present method, which requires only 20 microliters of bloodstain and only 5 min for the whole analysis.

Adult↗
PubMed1998

HPLC method for evaluation of the free radical-scavenging activity of foods by using 1,1-diphenyl-2-picrylhydrazyl.

An HPLC method for evaluation of the free radical-scavenging activity of foods by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) is reported. The activity was evaluated by measuring the decrease of DPPH detected at 517 nm. By using this novel method, we determined the free radical-scavenging activity of several antioxidants: ascorbic acid, alpha-tocopherol, Trolox, and cysteine. The results gave good correlation between the radical-scavenging activity determined by HPLC and by conventional colorimetry. This methodology was applied to determine the free radical-scavenging activity of 8 beverages. The activity of coffee was the highest, followed by red wine, green tea, oolong tea, black tea, rosé wine, white wine, and orange juice. The results well agree with those of previous reports. This method is expected to be useful for a simple and rapid determination of free radical-scavenging activity in colored foods, because coloring substances in foods do not interfere with the measurement.

Antioxidants↗
PubMed1980

Identification of the sialic acids from the egg jelly coat of the sea urchin Pseudocentrotus depressus (Okayama).

The jelly coat substance of the sea urchin eggs of Pseudocentrotus depressus (Okayama) was found to contain 0.35% sialic acids. After isolation of the sialic acids from the purified sulfated sialoglycoprotein containing 11% of sialic acids, analysis by colorimetry, thin-layer chromatography and gas-liquid chromatography/mass spectrometry demonstrated the nature of the sialic acids to be N-glycolylneuraminic acid and 9-O-acetyl-N-glycoloylneuraminic acid. The molar ratio between both sialic acids was found to be 1 : 1. Since it is known that O-acyl groups are partially released during the hydrolysis and isolation procedure, it can be assumed that in the native glycoprotein the percentage of O-acetylation is much higher than 50%. The sugar and sulfate composition of the glycoprotein is also described.

Animals↗
PubMed1994

Plasma pancreatic lipase activity: from analytical specificity to clinical efficiency for the diagnosis of acute pancreatitis.

Using five procedures (turbidimetry with the Boehringer Mannheim kit and with a home made reagent, reflectometry with the Eastman Kodak kit, colorimetry with the Sigma kit, and UV spectrophotometry with the Wako kit), lipase activity was assayed in the same group of 60 healthy adults and in 30 patients suffering from acute pancreatitis (n = 197 samples) as well as in a purified and stabilized preparation of human pancreatic lipase. Results indicated considerable inter-assay discrepancies for the mean values of the patients' results: catalytic activity concentrations differed by a factor of up to 16 according to the measurement procedures. For each method, mean patients' results were also expressed as multiples of the upper limit of normal values. This method of presentation did not significantly improve the intra-assay agreement, with maximal relative differences as high as 13-fold. When each method was calibrated with the same material (human pancreatic lipase), the inter-assay agreement was considerably improved. The causes of inter-assay disagreement are discussed in detail, and the necessity for a validated lipase calibrator is stressed, in order to improve the efficiency of the information transmitted by clinical laboratories to clinicians. A strategy is proposed, which includes development of a reference method and reference material, and a study of inter-assay commutability of secondary calibrators for a set of methods.

Acute Disease↗
PubMed1980

Comparison of several methods for the measurement of urinary hippuric acid as an index of toluene exposure.

The levels of hippuric acid in the urine of people exposed to toluene vapour were measured by paper chromatography, direct colorimetry, high performance liquid chromatography and gas chromatography. The control was a similar group not exposed to toluene vapour. The values were analyzed statistically, conversion equations calculated, and the propriety of these equation discussed. Since the three chromatographic methods gave similar values, the measurement of urinary hippuric acid by these methods can be used as an index of toluene exposure. The colorimetric method gave higher levels the chromatographic methods, especially for the urine of people not exposed to toluene. This may have been due to glycine conjugates (other than hippuric acid) developing a similar color, resulting in elevated values for hippuric acid. This colorimetric method should be used with caution for biological evaluation of workers with low toluene exposure.

Air Pollutants, Occupational↗
PubMed1981

Quantitative determination of urinary metabolites in subjects exposed to organic solvents.

Most of the common organic solvents are excreted into urine as metabolites. A correlation exists for several organic solvents between the amount taken in and the amount of metabolites excreted. Many methods have been developed for the measurement of these urinary metabolites. The methods were classified into three group: colorimetry, gas chromatography and high performance liquid chromatography. The characteristics and availability of these methods in a laboratory for routine work were reviewed. The correction equation for the amounts of metabolites in spot urine is discussed.

Chromatography, Gas↗
PubMed2006

Porphyrin-induced photogeneration of hydrogen peroxide determined using the luminol chemiluminescence method in aqueous solution: A structure-activity relationship study related to the aggregation of porphyrin.

A luminol chemiluminescence method was used to evaluate the porphyrin-induced photogeneration of hydrogen peroxide (H2O2). This method enabled us to detect H202 in the presence of a high concentration of porphyrin, which was not possible using conventional colorimetry. The limit of detection was about 1 microM. We compared the ability to generate H2O2, using uroporphyrin (UP), hexacarboxylporphyrin (HCP), coproporphyrin (CP), hematoporphyrin (HP), mesoporphyrin (MP), and protoporphyrin (PP). The amount of H2O2 photoproduced was strongly related to the state of the porphyrin in the aqueous solution. UP and HCP, which existed predominantly in a monomeric form, had a good ability to produce H2O2. HP and MP, existing as dimers, showed weak activity. CP, forming a mixture of monomer and dimer, had a moderate ability to produce H2O2. PP, which was highly aggregated, had a good ability. These results demonstrated that the efficiency of porphyrins to produce H2O2 was strongly dependent on their aggregated form, and the dimer suppressed the production of H2O2.

Colorimetry↗
PubMed1987

Nonenzymatic glycosylation of serum IgG and its effect on antibody activity in patients with diabetes mellitus.

Susceptibility to infection is assumed to be increased in diabetic patients, although its mechanism is unknown. The purpose of this study was to determine whether glycosylation of circulating immunoglobulins is related to the decrease of antibody activity in diabetic patients. Thirty-five patients with type II (non-insulin-dependent) diabetes and 14 age-matched normal controls were examined. Nonenzymatic glycosylation of serum immunoglobulin G (IgG) in vivo was measured by two different techniques, colorimetry and affinity chromatography. The levels of glycosylated IgG were significantly higher in diabetic patients than in normal controls. To evaluate the antibody activity of glycosylated IgG, anti-streptolysin O (ASO) titers after in vitro glycosylation of IgG and antibody titers before and after in vivo immunization with influenza vaccine were determined. IgG specific for streptolysin O purified by affinity chromatography decreased ASO titers after in vitro glycosylation. In diabetic patients, serum titers of hemagglutinin-inhibiting antibody against influenza viruses 4 wk after initial immunization were significantly lower than those in normal controls. These results indicate that serum IgG in diabetic patients was nonenzymatically glycosylated, and this modification in vivo might be associated with its functional alteration.

Adult↗
PubMed1988

Asymptomatic hyperbromidaemia detected as pseudohyperchloridaemia measured with an ion selective electrode meter.

Six patients were found to have increased serum chloride concentrations when these concentrations were determined with an ion-selective electrode, but not when determined by continuous flow mercuric thiocyanate colorimetry or amperometric-coulometric titration. Their serum bromide levels of 1.8-8.0 mmol/l were much higher than those of 0.07-0.13 mmol/l in normal controls. The urinary bromide excretion, measured in two of these patients, was higher than that in normal subjects. No common symptoms or abnormalities in laboratory findings except hyperbromidaemia were found in these patients, who claimed not to have taken any drugs containing bromide. For determination of the incidence of subclinical hyperbromidaemia, the serum bromide concentrations were measured in sera of 1,323 outpatients sent to Tokushima University Hospital for routine measurements of blood chemistry over a one-month period. Five samples showed abnormally high bromide levels. It is concluded that subclinical hyperbromidaemia is not as rare as generally thought, though the aetiology of this state is unknown. Chloride determination with an ion-selective electrode can be used to screen for hyperbromidaemia, since increased levels of bromide ion result in apparently high chloride values.

Adult↗