SEARCH · PubMed Health

Results for “Colorimetry”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources

PubMed1985

Membrane homeostasis: thermotropic behaviour of microsomal membrane lipids isolated from livers of rats fed cholesterol-supplemented diets.

Differential scanning colorimetry (DSC) has been applied to study the phase transition properties of isolated lipids from liver microsomal membranes of rats fed high cholesterol diets with or without high levels of either saturated (coconut oil) or unsaturated (sunflower seed oil) fat. DSC of aqueous buffer dispersions of liver microsomal lipids exhibited two independent, reversible phase transitions. The dietary cholesterol treatments had their major effect on the temperature at which the lower phase transition (T1) occurred. This transition occurred at a lower temperature when cholesterol was added to the diet, irrespective of the nature of the fatty acid supplement. However the magnitude of decrease was more when cholesterol was fed with sunflower seed oil. Inclusion of cholesterol into the rat diets also lowered the enthalpy values for the lower phase transition (T1). No appreciable effect on the temperature of the higher phase transition (T2) was observed, however the enthalpy values were slightly decreased by cholesterol feeding. These results suggest that certain domains of microsomal lipids, probably containing some relatively higher melting-point lipids, independently undergo solidus or gel formation and this transition (T2) is not greatly affected by dietary cholesterol. On the other hand, domains representing the bulk of the microsomal lipids undergo a phase change (T1) at temperatures which are dependent on cholesterol content and fatty acid profiles of the membrane, which are in turn, modified by dietary cholesterol intake.

Animals↗

PubMed1981

[Determination of proteinuria in children: changes in results according to the methods used (author's transl)].

Five methods for determination of proteinuria are compared : gravimetry, colorimetry (bromocresol green, Biuret test, Lowry's test), opacimetry (sulfosalicylic acid). Determinations were performed on normal urine, overloaded with albumin or gammaglobulins or on abnormal urine, after varying several parameters (pH, osmolarity, glucose, fructose, red blood cells, hemoglobin. leukocytes, germs). Some methods give non linear results depending on the concentrations (gravimetry, sulfosalicylic acid, bromocresol green). Some systematically give over-results (Biuret test, Lowry's test). Some almost exclusively determine albumin levels (bromocresol green, sulfosalicylic acid). In some, results are altered by glucose or fructose (Biuret, Lowry) or by red blood cells (Biuret, Lowry, sulfosalicylic acid). None of the tested methods can be used as a reference method. The method using sulfosalicylic acid is suitable for routine determination; however, results should be interpreted according to the parameters mentioned above.

Albuminuria↗

PubMed1978

Immobilized-enzyme nylon-tube reactors for routine determination of urea and citrulline in serum.

A continuous-flow clinical analyzer for the routine estimation of urea is described that makes use of an immobilized-enzyme nylon-tube reactor as part of a flow-through system (a Technicon AutoAnalyzer I). Results of blood-urea analyses by use of the immobilized urease are compared with determinations made with the diacetyl monoxime method and the urease solution method. Clinical trials carried out routinely with the immobilized enzyme nylon tube reactor give reliable and reproducible results with high precision and low cost. The reactors are stable to intermittent or continued use for at least four months or for 2000 tests. A method is described in which differential colorimetry is used for determining citrulline in blood and which makes use of the immobilized urease, albeit indirectly.

Autoanalysis↗

PubMed1984

Studies on the apoproteins of the major lipoprotein of the yolk of hen's eggs. V. Protein sulfhydryl groups: accessibility in the lipoprotein and the effect of temperature.

Sulfhydryl groups in the apoproteins of the major lipoprotein (density 0.95 g/ml) of hen's egg yolk have been studied by colorimetry, analysis for carboxymethylcysteine, and labelling with [14C]iodo-compounds and their distribution amongst the individual apoproteins (i.e. apovitellenins I-VI) has been determined. In the intact lipoprotein, reaction of sulfhydryl groups with aqueous reagents was slower than in the apoprotein mixture and there were large differences amongst different reagents in the extent of reaction. If the lipoprotein was heated for a short time in 1 mM EDTA above about 70 degrees C and then cooled, more sulfhydryl groups were accessible although the total number did not change. This increase in accessibility was accompanied by the disruption of the lipoprotein structure and an increase in the viscosity of its solutions. Furthermore, the isolated apoprotein mixture was less soluble in urea solutions and formed a gel, probably as a result of cross-linking by inter-protein disulfides. There was also a small change in the distribution of sulfhydryl groups so it is likely that sulfhydryl-disulfide interchanges occurred on heating. It is suggested that such interchanges help determine the physical properties of heated yolk and that in the intact lipoprotein sulfhydryl groups are concealed to prevent sulfhydryl-disulfide interchanges in the egg.

Animals↗

PubMed1983

Pseudoisochromatic plate design--Macbeth or tungsten illumination?

Three sets of pseudoisochromatic plates were evaluated by photometry and colorimetry. The luminance contrast between the figure and background was measured and compared with a contrast detection threshold. The chromaticity coordinates of the figure and background were evaluated on the basis of how closely they approached a dichromatic line of confusion. The separation of the coordinates of the figure and background are a measure of the severity of the defect for which the plate tests. The plates were evaluated under both Macbeth (C) and tungsten (A) illuminants; two sets of plates were found to be better designed for tungsten illumination.

Color Perception Tests↗

PubMed1984

Simple assay of estrogen in urine during pregnancy by means of latex agglutination inhibition reaction.

A simple and rapid method, latex agglutination inhibition reaction (LAIR), using anti-estriol-16-glucuronide coupled with BSA for estimating estrogen in urine has been developed. Agglutination of the latex reagent by the antiserum occurs within 3 min. The agglutination, however, was completely inhibited by 100 ng/ml or more of estriol. There was a good correlation in results obtained by LAIR and by colorimetry, RIA and GLC. Urine samples (3329) obtained at various gestational weeks were assayed. The samples from 94% of the normal pregnant patients in the third trimester revealed 10 micrograms/ml or more of estrogens. Although the assay is semiquantitative, it may be useful in screening for fetal well-being in high-risk pregnancies.

Estriol↗

PubMed1983

High performance liquid chromatographic and colorimetric determination of synthetic dyes in gelatin-containing sweets, following polyamide adsorption and ion-pair extraction with tri-n-octylamine.

Dyes are determined in gelatin-containing sweets. The gelatin must be eliminated first because it interferes with the normal ion-pair extraction of dyes with tri-n-octylamine to chloroform. Techniques such as precipitation of gelatin with organic solvents, and acid and enzymatic digestion of gelatin are shown to be unsuccessful because the remaining gelatin still influences the extraction scheme. Positive results are obtained when dyes are adsorbed on polyamide, gelatin is washed away, and dyes are desorbed with a methanol-ammonia mixture. Dyes are identified by thin layer chromatography and high performance liquid chromatography (HPLC), and quantitated by HPLC or colorimetry.

Adsorption↗

PubMed1981

Major developments in clinical chemical instrumentation.

The introduction of instrumentation into the clinical chemistry laboratory is reviewed for the period extending from about 1890 to 1960. Topics covered, from a historical point of view, include the microscope, analytical balance, and centrifuge, colorimetry and spectrophotometry, flame photometry, gasometric analysis, pH, electrophoresis, chromatography, radioisotopes, and automation.

Chemistry, Clinical↗

PubMed1981

[Energy expenditure of workers in a copper mill].

The results of the studies of energetic expenditure at 63 different workstations in copper mill were presented. 212 determinations of energetic expenditure were performed with direct colorimetry. 11% of the workstations exhibited a high energetic expenditure and hazardous working environment conditions. The results imply the necessity to modernize the mill and improve the preventive activities within industrial health service.

Adult↗

PubMed1995

[A preliminary study on etiology of atrophic rhinitis in Zunyi].

200 cases (households with atrophic rhinitis (AR) diagnosed from outpatients and mobile medical team as the AR group were studied. Another 200 cases (households) served as the control group, who were residents of countryside and members of a factory in Zunyi, and they have lived in Zunyi for more than 20 years. The subjects between the two groups were similar in age and sex. Each of these two groups was further divided into two groups, the opentype stove group (100 cases) and the closetype stove group (100 cases). The heritability (h2, 59.4 +/- 0.032%) was estimated by using the method of Falconer liability threshold. The concentration of SO2 in living environment was monitored with Parafuchsin colorimetry. The daily average SO2 concentrations have been drawn for comparison. The result showed that the SO2 concentration of living environment in AR group was significantly higher than that in control group (P < 0.01). We believe that the contraction and development of AR were determined by the combination of inheritance with environment. This fact suggests that AR may be transmitted in a multigenic and multifacterial modes.

Adolescent↗

PubMed1993

Pharmacological activity and local and systemic tolerance of topically applied iloprost.

The chemically stable prostacyclin derivative iloprost (CAS 73873-87-7) infused intravenously induces vasodilation and inhibits platelet aggregation. Numerous clinical studies have shown that iloprost is beneficial in the treatment of obliterative arterial disease. As a topical therapy would have considerable advantages, the pharmacological activity and the tolerance of the drug was evaluated in several studies which included 73 healthy volunteers. The drug was tested in different galenical formulations: aqueous solution, various hydrogels and a fatty ointment. They were applied to intact as well as experimentally damaged (stripped) skin. The pharmacodynamic effects were determined by visual assessment, colorimetry and laser Doppler velocimetry. Moreover, the volunteers were monitored for systemic side effects including changes in blood and urine. After the solution was applied under occlusion, iloprost induced erythema at dose levels of at least 50/25 ng/cm2 (intact/stripped skin). Applied to intact skin, erythema lasted for up to 5 days. When the drug was applied to stripped skin the effect was shorter (24 h). Following low doses, erythema was confined predominantly to the follicles whereas homogeneous redness was induced by higher iloprost doses. Thus penetration seems to occur in particular via the follicles with the horny layer acting as a penetration barrier and as a drug reservoir. High doses (400/150 ng/cm2) induced edema in all cases when applied to intact/stripped skin. When applied to large areas of the skin, increased iloprost serum levels (< or = 80 pg/ml) as well as systemic side effects (inhibition of platelet function, flush, headache) were observed. Tachyphylaxia did not develop after the application of 25 micrograms/100 cm2 once daily for 60 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗

PubMed1993

[Determination of potassium iodide in Polish edible salt].

The purpose of the study was to assess the correctness of salt iodination and its distribution in Poland. The subject of the study was salt for human consumption iodinated or not, according to Polish norm PN-88/C-84081/02 "Sól (chlorek sodowy). Requirements. Salt samples were taken from retail shops or stores in 36 provinces. The study was carried out in the years 1992-1993 according to PN-80/C-84081.35 "Sól (chlorek sodowy) standard. Potassium iodide was determined by photo-colorimetry. The total number of studied salt samples was 3418, including 2440 samples of iodinated salt. The per cent of samples with proper content of potassium iodide was from 30% to 50% depending on the producer. The study demonstrated that in most cases the process of salt iodination is done incorrectly.

Poland↗

PubMed1993

[Study on compound levonorgestrel microspheres].

Levonorgestrel (LNG) and estradiol (E2) were mixed in the ratio of 5:2 by weight. Compound LNG gelatin-microspheres were prepared by phase-separation method, natural biodegradable gelatin being used as the core material. The experimental conditions were optimized, the mean diameter of the microspheres obtained being 10-40 microns, and the rate of encapsulation 65-75%. Storage observations and acceleration tests of the compound LNG gelatin-microsphere injection prepared showed that the microspheres have good stability. The thermal degradation activation energy of the injection was determined to be 134.4 kJ/mol, based on differential scanning colorimetry (DSC). T1/2 values for dissolution in vitro of LNG and E2 from the compound LNG gelatin-microsphere injection and from the unencapsulated injection showed significant difference (P < 0.01), indicating that the microspheres have good sustained release action. Effects of the pure LNG microsphere injection and compound LNG microsphere injection on the mouse ovary were compared histologically. The results showed that the compound LNG microsphere injection reduced some of the side effects such as ovary congestion. This points out that the compound dosage form can clinically alleviate the irregular bleeding caused by the administration of LNG alone.

Animals↗

PubMedDate not supplied

[Effect of soybean protein isolate on energy substrate oxidation in patients with insulin-dependent diabetes mellitus].

Using indirect colorimetry, the authors demonstrated disordered energy metabolism at rest in patients with insulin-dependent diabetes mellitus (IDDM) with a moderate decompensation of metabolism: carbohydrate oxidation was reduced and fat and protein oxidation increased, this being aimed at maintenance of the basic metabolism within the normal range under conditions of insulin insufficiency. Improvement of common parameters of compensation during optimization of insulin therapy and therapeutic diets was associated with approximation of substrate oxidation structure and energetic structure of a diet, as well as with increased production of useful energy coupled with reduced oxygen consumption. Moreover, a positive correlation between insulin level and carbohydrate oxidation rate was revealed. Analysis of the effects of qualitative composition of protein showed a more rapid improvement of metabolism during metabolic diet, whereas during therapy with diets including soybean protein increase of metabolism efficacy is more manifest. Bioenergetic parameters may be used as criteria of the efficacy of IDDM treatment. Changes in these parameters not always correlate with the time course of routine criteria of compensation and provide supplementary information on a patient's metabolic status.

Adolescent↗

PubMed1993

[Effect of processing on phospholipid of Dioscorea opposita Thunb].

A study of the chemical changes of phospholipid in crude and seven processed samples of Dioscorea opposita was carried out by molybdenum blue colorimetry and TLCS. The result shows that the total phospholipid content in the sample processed by honey bran comes out the highest (180.31 mg/100g).

Chromatography, Thin Layer↗

PubMed1993

Detection of antifood IgE by in vitro tests and diagnosis of food allergy.

The diagnosis of IgE-dependent food allergy relies on the demonstration of specific IgE by prick tests or biological tests. A radioimmunoassay (RAST Phadebas) is completed by several immuno-enzymatic methods: RAST Phadezym, FAST, MAST-CLA, AlaSTAT, etc. The allergen is bound to solid or liquid phases, by different binding agents. Various enzyme-substrate systems, and several systems for expression are used (RIA, fluorescence, chemoluminescence, colorimetry, etc.). Another aspect of modern technics is the trend towards high automated processes. A second group of tests aims to detect the release of mediators from sensitized basophils: leucocyte histamine release test, human basophil degranulation test and a leucocyte leukotriene release test. The specificity of tests for detection of anti-food IgE is lessened by numerous cross reactivities between pollens, fruit, and vegetable. The study of the sensitivity of such tests needs strictly standardized food challenge tests in order to firmly establish the diagnosis of food allergy. Multiscreen tests have to be assessed, in order to validate their efficacy for detecting frequency allergens. Whatever the test to be used, its positivity means only sensitization, and food challenge tests are mandatory to recognize true food allergy, as latent sensitization to food is a current phenomenon in atopic children. The possibility of reliable diagnosis of food allergy by using challenge tests makes now possible and advisable to set up quality controls for all biological tests applied to the detection of antifood IgE, thanks to the possibility to dispose of reference sera.

Adult↗

PubMed1977

Cortisol production rate determined by radio gas-chromatography.

We describe a ratio gas-chromatographic method for determination of cortisol production rate by measuring the isotope dilution of urinary cortisol metabolites. The method was calibrated by analyzing [3H]tetrahydrocortisol and [3H]tetrahydrocortisone of known specific activities. Results are reasonably well reproducible, the coefficients of variation ranging from 8-15% of allotetrahydrocortisol/tetrahydrocortisol and from 9-19% for tetrahydrocortisone. Correlation coefficients were 0.966 and 0.998 for tetrahydrocortisone and allotetrahydrocortisol/tetrahydrocortisol, respectively, when the method was compared with a method involving thin-layer chromatography and colorimetry. Only one chromatographic step is needed for both purification and quantitation, thus time and effort are saved.

Chromatography, Gas↗

PubMed1977

Simple procedure for measuring total protein in urine.

We describe a procedure for measuring total protein in urine. The method is simple, sensitive, and free of interference from drugs that are known to affect other commonly used methods. The CV for a 1.1 g/liter urine control in daily, routine use is 4.6%. The procedure involves adsorbing the protein onto cellulose powder, binding of Ponceau S dye by the protein, washing away excess dye, and eluting the bound dye into dilute NaOH for colorimetry. Comparison of results by this method with those by the biuret and turbidimetric procedures showed good agreement in those cases where the specimens were suitable for assay by the comparison methods.

Biuret Reaction↗