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At least 19 recordsLinked to original sources
PubMed1975

[New bases and theories from improving angio-cine-densitometry. II Improvements in the signal-to-noise ratio by the quotient method in cine densitometry].

In radio-cine-densitometry, random variations can be smoothed and reduced in two ways: temporal (frame to frame) and spatial (each frame). Both methods may, however, alter the signal measurements. The advantage of quotient cine-densitometry depends on the elimination of interference or random variations without changing the signal. Elimination of the variations occurs during signal recording. Amongst others the following are eliminated: variations in mains voltage, uneven development, absorption by other tissues and organs. A more suitable signal-to-noise ratio can be obtained. If an artery or a vein are opacified simultaneously it is possible, by means of quotient cine densitometry, to distinguish the arterial and venous phase and to analyse these separately from the overlying tissues.

Absorptiometry, Photon↗
PubMed1975

[A new basis and theories for improving angio-cine-densitometry. V. The effect of the injection method of the contrast on measurements during angio-cine-densitometry (author's transl)].

The theoretical basis for measuring speed of flow in vessels of conscious patients obtained by estimating dilution of injected contrast is described. Previously, measurements at two separate points had to be carried out in order to obtain a flow profile, but with the present method, a single measurement point is adequate. If contrast is distributed evenly in the circulation during its flow to the periphery, the measurement can be carried out at some distance from the point of injection. The ability to select ones point of measurement makes it possible to avoid areas covered by overlying shadows and eliminates the difficulties inherent in measurements in curved vessels.

Absorptiometry, Photon↗
PubMed1979

Reliable estimation of hemoglobin A2 concentration by electrophoresis with densitometry.

Elevated hemoglobin A2 (Hb A2) levels can be identified conveniently by densitometry after electrophoresis on cellulose acetate strips. Because a recent report questioned the accuracy of this technic, the method was re-evaluated by paired comparison with microcolumn chromatography. Analysis of 100 patient specimens showed high correlation (r = +0.84), but an average Hb A2 concentration 0.7% higher by densitometry than by chromatography (P less than 0.001). With upper limits set at 4.5%, and 3.8%, respectively, results were divided into "normal" and "high" for each method. Concordant results were obtained in 97 of the 100 cases (82 normal, 15 high). Another densitometer of improved design was used for paired analysis of 50 additional specimens, 25 normal and 25 with beta-thalassemia trait. The two groups were well separated by both procedures, and Hb A2 levels were similar (r = +0.92, P greater than 0.6). This study demonstrates that it is possible, with carefully controlled technics and properly calibrated instruments, to use electrophoresis with densitometry as a reliable means of identifying abnormal Hb A2 levels.

Child↗
PubMed1978

A rapid, sensitive method for accurate analysis of individual bile acids in biological fluids by high performance thin-layer chromatography and densitometry.

1. A rapid new micromethod for quantitative analysis of individual bile acids in duodenal juice by high performance thin-layer chromatography (HPTLC) and densitometry is described and evaluated by comparison with standard TLC and spectrophotometry. 2. Advantages of HPTLC over TLC include more rapid separation, better resolution and more sensitive detection (5 - 10 fold), without the need for prior extraction. Densitometry provides simple, direct and rapid quantitation. 3. The method is accurate and reliable over a range of bile acid concentrations. In the 0.5 mM range, recovery was greater than 89%, and coefficients of variation for within-day analysis were 2 - 12% and for between-day analysis were 6 - 18% for the individual bile acids. Twenty analyses can be performed by one worker in a single day. 4. We conclude that the method offers several advantages over most currently described techniques, is suitable for routine use and is deserving of wider application.

Bile Acids and Salts↗
PubMed1975

[New basic considerations and theories for improving angio-cine-densitometry. IV. The effect of discontinuous, pulsatile flow on angio-cine-densitometric measurements (author's transl)].

Various expressions of the speed of flow of blood in arteries are discussed, such as instantaneous speed, integral speed, pulse wave speed (phase speed) and velocity of a moving front. The flow profile of the abdominal aorta was obtained by cine-densitometry, bearing in mind the above considerations, and the densitometric curves have been analysed. Differences of the flow velocities in different persons have been interpreted as a result of these theoretical considerations. The effects of the point of measurement, the distance over which the measurement was carried out and the pulse wave length on velocity were examined. In order to obtain a median blood stream velocity by angio-cine-densitometry, repeated injections of small volumes of contrast medium (random sampling method) are recommended.

Blood Flow Velocity↗
PubMed1975

Atomic absorption spectrophotometry applied to photographic densitometry.

For this study of photographic densitometry, sections of cartilage stained with Alcian Blue, safranin O and high iron diamine were photographed at x40 with Nikon photomicrography equipment on Kodak Panatomic X film with appropriate filters to enhance contrast. Portions of the developed negative films were selected from intercellular matrix regions, and circles of film equivalent in diameter to a 30-mu circle of tissue were obtained with a hand-held paper punch. Silver was eluted from the circles of film with 35% nitric acid, and the quantity of silver deposited on the film was determined by atomic absorption spectrophotometry as a measure of stain intensity. The intensity determined by this analytic procedure compared favorably with results obtained previously from the same tissue with microspectrophotometry. This method of silver analysis has advantages over earlier studies which used silver elution to determine photographic densitometry in its technical ease, accuracy and sensitivity. Furthermore, this method compares well with microspectrophotometry in its results and has the advantages of relative inexpensiveness and availability of equipment.

Animals↗
PubMed1977

Clinical evaluation of bone-densitometry in patients with final renal insufficiency operated for hyperparathyroidism.

Because of difficulties in evaluating bone mineral mass with conventional methods in patients with final renal insufficiency before and after parathyroidectomy, bone densitometry has been tried. During a three year period ten patients have been selected for surgery. The parathyroidectomy performed was total in nine patients and subtotal in one. Bone mineral mass was significantly lower preoperatively in the operated patients than in other patients on regular hemodialysis and also lower than in a normal material. In four of ten patients there was a transient decrease in bone mineral mass after parathyroidectomy. Thereafter there was a significant increase in five of ten patients and in the whole group of patients. Thus bone densitometry was found to be of value in following patients with renal insufficiency selected for parathyroidectomy.

Adult↗
PubMedDate not supplied

Associated problems of protein electrophoresis, staining and densitometry.

The process of electrophoresis, a separation phenomenon, is mistakenly understood to include the sequential processes ancillary to analyte resolution, that is, staining and quantification, where the latter could be elution followed by photometry or integrating-calculating-densitometry. The theories involved in electrophoresis itself are well worked out and equally well understood but the problems which are associated with separation, chemical reaction to generate a chromogen and quantification, perhaps partly forgotten and perhaps partly ignored, are taken up and described here. They include albumin trail, resolution, unequivalent staining, prestaining and the densitometry problems associated with band widths, opacity effects and polychromaticities.

Blood Proteins↗
PubMed1977

Computer densitometry for angiographic assessment of arterial cholesterol content and gross pathology in human atherosclerosis.

Sequential change studies in human atherosclerosis are desirable in disease regression trials but are now limited by dependence on the occurrence of epidemiologic end-points. Prior radiographic studies have pertained to advanced obstructive atherosclerosis. This is a study of measures applied by computer-generated densitometry of angiograms to assess early to advanced nonobstructive atherosclerosis. Measures are based on pathologic and angiographic appearance of all stages of atherosclerosis and include image edge roughness, local width, and local contrast density changes. Femoral angiograms were made in 21 cadavers under simulated clinical conditions, with a pressurized radiopaque casting material. Full-size color photographs were made of 10 cm. segments of opened artery, with matching cast and arterial specimens analyzed for cholesterol content. Four graders, on two occasions, sequenced the photographs in increasing order of disease on the basis of the International Atherosclerosis Grading scheme. The correlation between the two sessions was 0.93. Thirteen computer indices correlated significantly with visual grade and cholesterol and were allowed to compete in a step-wise regression for best indices of prediction. Computer index correlation coefficient for visual grade prediction was 0.86, and for cholesterol content, 0.84. Computer densitometry measurement appears useful in the evaluation of all stages of atherosclerosis as recorded angiographically and obviates the necessity for exacting visual comparisons of large numbers of films.

Angiography↗
PubMed1978

[Attenuation values of normal and pathological liver tissue as a basis for computer tomographic densitometry of fatty livers (author's transl)].

Measurements of the density of normal and diffusely disease liver parenchyma show a significant difference only in the presence of fatty livers. A linear relationship between the fat content and density (g/cm3) has been demonstrated. Computer tomographic densitometry of liver tissue correlates well with physical in vitro measurements and permits measurements of fat content which are sufficiently accurate for clinical use. Other types of liver disease cannot be differentiated by densitometry.

Absorptiometry, Photon↗
PubMed1978

Determination of individual hydroxyethyl rutosides in various animal body fluids by thin-layer chromatography and scanning densitometry.

A method is described for the accurate determination in plasma of the beta-hydroxyethylrutosides by measurement of the fluorescence of their borocitrate complexes by scanning densitometry following separation by thin-layer chromatography. A modification is also described for estimation of individual hydroxyethylrutosides and their glucuronide conjugates in samples of bile and urine.

Animals↗
PubMed1979

An objective method for measuring fluorescence of individual sperm cells labelled with 1-anilinonaphthalene-8-sulphonate (ANS) by means of photomicrography and densitometry.

A method is presented for measuring the degree of fluorescence of sperm cells labelled with 1-anilinonaphthalene-8-sulphonate (ANS). Labelled spermatozoa were subjected to incident-light u.v. illumination and the fluorescent image was photographed. Densitometry of the photographic film yielded values for individual sperm heads, and the mean value for ten cells formed the unit of data for parametric statistical analysis. The method is both objective and precise, and was used to distinguish between treatments applied to the spermatozoa. It is believed that the method has a wide application as an inexpensive means of fluorimetry.

Anilino Naphthalenesulfonates↗
PubMedDate not supplied

Geometrical considerations for Compton scatter densitometry.

The determination of the physical density by Compton scatter densitometry is dependent upon the geometry used for the measurement. The diameter of the sample, the density range, and the scattering volume size and shape influence the relative electron density values obtained by such a system. This work presents the results of an experimental analysis of these parameters in which the importance of each is evaluated for samples of known density. A bias in the computed Compton density, due to multiple scattering and attenuation, is defined; and an expression relating the density bias to these geometrical parameters is presented. The importance of applying corrections to the computed physical density for samples of large diameter and/or high density (cortical bone tissue and large diameter cancellous bone tissue) is discussed.

Bone and Bones↗
PubMed1979

Bone densitometry using computed tomography. Part II: increased trabecular bone density in children with chronic renal failure.

The method of gamma-ray computed tomography (gamma-ray CT) bone densitometry described in the preceding article provides selective determination of trabecular bone density (TBD), the relative amount of compact bone (bone density, BD), and the total absorption (TA) within a bone cross section. Seven of nine children with chronic renal failure (CRF), and selected only on the basis of their serum creatinine value (greater than 5 mg/100 ml), had increased TBD values above the normal range, whereas the other bone mineral parameters were normal. Radiographic signs of secondary hyperparathyroidism (subperiosteal erosions, cysts) were reported in the five patients with the highest TBD values, whereas the subjective diagnosis of osteosclerosis reported in three of these five and in one other patient correlated less well with the TBD increases. However, this is the first report of an objective, non-invasive documentation of the radiological finding of osteosclerosis in CRF. It also explains why methods for bone mineral measurements used previously, such as a photon absorptiometry which provides only a parameter equivalent to TA, failed to reveal increases in bone mineral content in renal osteodystrophy even when signs of osteosclerosis were present. Thus, gamma-ray CT helps to document objectively the degree of osteosclerosis and its location.

Adolescent↗
PubMed1977

[The use of an internal standard for the correction of deviations in densitometry of thin-layer chromatograms (author's transl)].

In order to obtain a better reproducibility in quantitative determination of amino acids in amounts of picomoles an internal standard was used. A mixture of ten amino acids was diluted and dansylated. 0.1 microliter of each solution was separated by two-dimensional thin-layer chromatography on polyamide sheets (3 x 3 cm). Each chromatogram was photographed with four different exposure times under ultraviolet light. The dark spots in the photographic negatives were measured by television densitometry. A number of factors influence the reproducibility of this method: loading volume, photographic exposure time and processing, and quenching of fluorescence. As an internal standard, which is influenced by all these factors, DANS-hydroxyproline was added to each solution. By using this standard, the variations in exposure time and fluorescence quenching can be corrected satisfactorily. The relative standard deviation of the mean value of four photographs of one chromatogram is 2%. The results on correction of the volume deviation were not so satisfying. The relative standard deviation of the mean of twelve different chromatograms can be reduced from 34% for the initially measured data, to 8% for the values corrected by the internal standard. It seems necessary to carry out three or more determinations of one solution. In this case the relative standard error of the mean is 2%.

Amino Acids↗
PubMed1978

Quantitative determination of carbaryl in apples, lettuce, and water by densitometry of thin layer chromatograms.

A method for the quantitative determination of carbaryl insecticide by in situ densitometry was developed. After separation on silica gel thin layer plates, carbaryl residues were detected by using p-nitrobenzenediazonium fluoborate reagent and quantitated by scanning the resultant blue spots with a fiber optics densitometer and comparing them with standards. The method was applied to water fortified with carbaryl at 8 ppb and apples and lettuce fortified at 0.10 ppm; all recoveries were greater than 89%. The 2 crop extracts were cleaned up by using the AOAC thin layer chromatographic method for visual estimation of carbaryl. Related carbamate insecticides were detected by using the same reagent, and the potential for quantitation was demonstrated.

Carbaryl↗
PubMed1979

[Phenobarbital determination using direct densitometry of thin-layer chromatography].

A report on the determination of phenobarbital in model specimens of plasma and blood using direct densitometry of thin-layer chromatograms, namely by measurements of fluorescence quenching using remission technique following previous conversion of phenobarbital to sodium salt. Phenobarbital is extracted by three fundamentally different techniques, the results of estimation are given statistical evaluation, and the yield of each of the techniques is compared. Since the processing of 1 ml serum still allows the estimation of quantities as low as 1 microgram per stain the proposed method can be recommended for the determination of toxic levels of phenobarbital in plasma or in blood.

Chromatography, Thin Layer↗