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At least 631 records · Page 35Linked to original sources
PubMed1978

Quantitative determination of chlordiazepoxide and its metabolites in serum by fluorescence TLC--densitometry.

A sensitive fluorescence TLC--densitometric procedure was developed for the specific determination of chlordiazepoxide (I) and its two metabolites, demoxepam (II) and desmethylchlordiazepoxide (III), in serum. After extraction from serum with ether, I, II, and II were separated by TLC and converted with a sulfuric acid spray to pale blue (Rf 0.63), green (Rf 0.54), and blue (Rf 0.45) fluorescence spots, respectively. Quantitation was accomplished by scanning the plate with a densitometer at 390 (I), 430 (II), and 390 (III) nm. The sensitivities were 0.05 (I), 0.01 (II), and 0.01 (III) microgram/ml of serum. The procedure was successfully applied to measurement of I-III in human serum after oral administration of 20 mg of chlordiazepoxide hydrochloride.

Chlordiazepoxide↗
PubMed1986

Projective MRI angiography and quantitative flow-volume densitometry.

Projective MR images of vascular anatomy and flow are performed at 0.14 T by using phase contrast to suppress the signal contribution of the stationary background. The source of the contrast is the distinctive phase evolution of moving protons under the influence of the read-out gradient of a conventional two-dimensional Fourier transform (2D FT) spin-echo pulse sequence. By using short echo times, small phase shifts may be obtained. When phase shifts are less than about 45 degrees, the phase contrast assumes a simple and useful form. The flow image intensity at any pixel becomes proportional to the net flux or flow volume of protons which cross the corresponding voxel. This proportionality is demonstrated in images of flow phantoms as is the reproducibility of measured flow volume under a variety of transformations of imaging conditions and of the subject. Projective images gated in vivo produce angiographic views of arteries and veins, in systole and diastole, in the neck of a dog and in the lower extremities of a human subject.

Animals↗
PubMed1996

Ultramicro-analysis by use of light-scanning photoacoustic densitometry for electrophoresed protein in human hair.

A technique was developed for the ultramicro-analysis of proteins electrophoresed by Laemmli's method using a light-scanning photoacoustic densitometer. After electrophoresis, the proteins were blotted on a nitrocellulose membrane filter and colored by the avidin-biotin complex method. This filter was then measured using a photoacoustic densitometer. The optimal blotting time was 150 min. The relative standard deviation of four measurements was 3.89% for 200 ng bovine serum albumin (BSA). The limits of detection were 2.3, 0.69, 4.4, and 2.9 ng (S/N = 3) for BSA, ovalbumin, carbonic anhydrase, and alpha-Lactoalbum respectively. Proteins eluted from hair by various harmful agents, such as a surfactant and UV irradiation, were analyzed by the present method. Using 2-mercaptoethanol, the molecular weights of proteins in hair were in the range of 14,000-64,000. Maximal elution of protein was obtained at pH 8. More protein was eluted under alkaline conditions than under acidic conditions. A protein of Mr 68,000 was eluted from hair by oxidative treatment with either UV irradiation or sodium bromate.

Acoustics↗
PubMed1995

Bone densitometry.

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Bone Density↗
PubMed1995

Ultrasound, densitometry, and extraskeletal appendicular fracture risk factors: a cross-sectional report on the Saunders County Bone Quality Study.

The Saunders Bone Quality Study was designed to determine the feasibility of ultrasonic bone measurement, at the patella, as a predictor of low-trauma fractures in a rural population-based study. At the first visit of this 4-year longitudinal study, anthropometric and clinical measurements and medical, surgical and fracture histories were obtained for the 1428 participants 9899 women and 529 men). Explored risk factors for low-trauma fractures included age, sex, calcium intake, alcohol and caffeine ingestion, tobacco use, body mass and grip strength, age of menopause, estrogen replacement therapy, propensity to fall, distal radius and ulna bone mineral content, and bone density. Forward multivariate logistic regression analysis showed that lower ultrasound values are more consistently associated with reported low-trauma appendicular fractures than the commonly reported forearm absorptiometry measures of radius mineral content and density. When ultrasound, age, and the extra skeletal risk factors were included in an additional multivariate model, only age and ultrasound were significantly associated with appendicular fracture history in women (P = 0.0003), whereas only ultrasound was associated in the men (P = 0.001). We conclude that ultrasound is a better measure as association with reported low-trauma fractures than the commonly reported forearm SPA measures. Even after adjustment for many of the extra skeletal risk factors, low AVU is highly associated with low-trauma fracture status for both men and women.

Age Factors↗
PubMed1977

High-resolution scanning-densitometry of photographic negatives of human chromosomes. III. Determination of fluorescence emission intensities.

Principles and techniques are discussed for measuring with high topological resolution local emission in fluorescing objects, using photographic negatives. Determination of fluorescence intensities is only possible when an unequivocal relation between the original local fluorescence emission intensities of the object, and the transmittances or densities recorded in the microfluorophotograph is known. This relation is formulated in the theoretical part. From this relation it can be concluded that the recorded intensities can be measured optimally when the optical density values produced by the fluorescence emission fall in the range of the linear portion of the Hurter and Driffield curve. In order to obtain this situation, a uniform low-level pre-exposure of the film emulsion to (white) light is carried out prior to the actual fluorescence emission exposure. This pre-exposure acts to elevate the signal exposure to the linear (steeper) part of the H.D. curve. Inhomogeneity of the excitation beam in the object field, or differences in film emulsion response to the light exposure, will result in erroneous optical densities recorded in the photographic negative. Correction for such artifacts could be obtained by addition of a low concentration of fluorophore to the mounting medium of the microscopic preparation. The overall fluorescent background produced in this way, enabled calibration of local fluorescence intensities in different parts of one fluorophotographic negative, and also of the intensities in different negatives taken from one microscopic preparation. The validity of this approach was checked by comparing data obtained from several photographic negatives of the same quinacrine-stained metaphase, taken with different exposure times to imitate fluctuations in excitation illumination, after conversion of the scanning data into emission intensity values with an alogarithm based on the proposed theoretical relation. In another experiment, fluorescence emission intensities of Feulgen-stained chromosomes which had been measured with a cytofluorometer, were compared with results obtained by conversion of the scanning data measured in the fluorophotographic negatives of the same metaphases. Both types of experiment confirmed the applicability of the procedure described.

Chromosomes↗
PubMed1977

[A new image-processing system designed for densitometry and pattern analysis of microscopic specimen. Application to the automated recognition and counting of cells in the various phases of the mitotic cycle (author's transl)].

A new image analysing system, designed for microphotometric measurement and pattern recognition has been applied in the discrimination of cells from the various phases of the mitotic cycle. The data acquisition procedure is controlled by a programmable electronic unit and involves the combination of the shifting of the microscope moving stages and the scanning of the successive fields by a mechanical device. The data processing is achieved by a computer. The preliminary results we obtained have shown that such a system allows the automatic recognition and counting of the M, G1, S and G2 cells as also the G0 resting cells. The most useful parameters of the cell proliferation kinetics are thus obtained from a single specimen of a cell population.

Cell Count↗
PubMed1992

Correlations between densitometry of red-free photographs and reflectometry with the scanning laser ophthalmoscope in normal subjects and glaucoma patients.

OBJECTIVE: To compare image measurements of the retina produced by scanning laser ophthalmoscopy with those from red-free photographs (RFP) of the nerve fibre layer. SUBJECTS: The left eyes of 23 subjects (10 normal, 7 glaucoma suspect and 6 glaucomatous) were included in this study. METHOD: All the eyes were photographed using standard red-free photography, and images of the retina were digitised directly from the SLO. RESULTS: The correlation coefficient for all except three subjects was > 0.45, and the probability (p) that R = 0 was < 0.05 in all but 5 eyes. CONCLUSIONS: The data indicate that variations in retinal surface reflectivity as measured by the SLO are similar to those recorded on negative film during RFP. This further suggests that the SLO can be useful for making objective measurements of the RNFL, without the intermediate and variable steps of photography.

Densitometry↗
PubMed1989

Analysis of brain and myelin lipids by high-performance thin layer chromatography and densitometry.

We have developed a simple method involving high-performance thin layer chromatographic separation of total brain and myelin lipids. Only two solvent systems consisting of chloroform: methanol:acetic acid and water at different concentrations were needed. The plate was then stained with three sequential procedures to visualize phospholipids, cholesterol and galactolipids. Densitometric procedure at each step of staining was utilized to obtain quantitative analysis of brain and myelin samples.

Animals↗
PubMed1995

Nuclear morphometry and DNA densitometry of human gliomas by image analysis.

In 48 patients with gliomas in whom complete clinical follow-up was obtained, DNA ploidy was evaluated by using formalin-fixed paraffin-embedded tissues and by means of image analysis. The mean DNA indices, determined by averaging DNA indices of all tumor cells in a tumor, were mainly affected by mean DNA indices of the nuclei of SG2M phase tumor cell (including S phase and G2M phase cells) (SG2M DNA indices) and that mean DNA indices correlated with the SG2M phase fraction. The SG2M DNA indices and the percentage of tumor cells with S phase and G2M phase were higher in high grade gliomas including anaplastic glioma and glioblastoma multiforme than in low grade gliomas. Patients with G2M-hypertetraploid tumors demonstrated a shorter time to tumor progression than those with G2M-tetraploid in high grade glioma. Morphometrically, the nuclei of SG2M phase glioma cells were larger and more deformity than those of G0G1 phase (including G0 phase and G1 phase cells) cells. The G2M-hypertetraploid tumors were highly malignant and demonstrated large nuclei, greater nuclear deformity, and a higher proliferative potential. The G2M-tetraploid gliomas demonstrated a shorter time to tumor progression in cases whose the SG2M fraction was large. In contrast, G2M-hypotetraploid gliomas revealed an insignificant trend towards a longer time to tumor progression than those associated with tetraploid and hypertetraploid gliomas. We emphasize herein the prognostic importance of the SG2M phase cell, as well as other proliferation indices.

Adolescent↗