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At least 433 records · Page 24Linked to original sources
PubMed1984

Quantification of proteins in tracheobronchoalveolar lavage fluid by isoelectric focusing and scanning densitometry. A methodological study on rats.

The aim of this study was to evaluate whether isoelectric focusing is a technique that is capable of quantifying a number of proteins simultaneously, in a single analysis of tracheobronchoalveolar lavage fluid. The aim included presentation of an animal model for such analysis after exposure to a pulmonary irritant. The studies were performed on tracheobroncoalveolar lavage fluid from rats. One-millimetre-thick agarose gels were used. The gel plates were stained with Coomassie Brilliant Blue R 250, which primarily stains proteins. Quantification of different protein bands was performed by laser scanning densitometry and computerized processing of the results. The effects of different steps in the analysis were examined. Recommendations for application of the method are proposed. An investigation was also made of the variance for the entire method, the variance attributable to isoelectric focusing and individual variation, for different protein bands. A light-microscopic examination for mechanical injury caused by tracheobronchoalveolar lavage was performed. The effects of perfusion of the pulmonary circulation with 0.9% sodium chloride solution during lavage was investigated. Application of the method in an experiment in which rats exposed to tobacco smoke were compared with rats not thus exposed showed that the method is powerful enough to show significances between these two groups. Corresponding results were obtained when rats, the pulmonary circulation of which was perfused as stated above, were compared with non-perfused rats. The experiments showed that isoelectric focusing combined with laser scanning as applied in this study, can be used for quantification of a system of proteins in tracheobronchoalveolar lavage fluid when different groups are to be compared.

Animals↗
PubMed1983

[Pharmacologic effects of contrast media in angio-densitometry].

Angio-densitometry is a very sensitive method in the evaluation of vascular effects of a contrast medium. For that purpose the renal circulation is especially suitable. The method is based on the zero or subtraction method. Thus, the majority of the well known interference sources will not be recorded. Only changes of density caused by the passing blood are measured. Four different contrast media are compared. Their effects on the circulation cannot be predicted from a single measurement. The mean value of several measurements limits the scattering range and allows comparisons to be made. Accordingly there are some differences between the examined conventional contrast media and their influence upon the kidney circulation. They all slow down the blood velocity in the renal artery, but the extent is different. The causes responsible for the circulatory effects of the contrast media are discussed on the basis of current scientific knowledge. In addition the results of 144 angio-densitometric studies are reported. The analysis of the pharmacological effect of meglumine iothalamate (Conray 60) revealed only an unimportant influence upon the renal circulation.

Angiography↗
PubMedDate not supplied

[Correlation of the histological structure of gliomas with densitometry findings during computer tomography].

Local features of the histological structure of malignant glioma tissue are compared with the results of densitometry in computer tomography (CT) with a contrast amplifier. The material for histological examination was collected during stereotaxis biopsy conducted according to CT findings (9 patients) and in examination of the brain of 5 patients who had died without being subjected to operation. The method by means of which anatomical axial sections identical to a series of CT sections were obtained is described. The results in the form of mean values of the coefficients of absorption and the homogeneity of their distribution are shown in accordance with the density of areas with intact brain in each CT section. These data make it possible to detect details of the CT image which are not accessible to visual analysis in some cases and to appraise more objectively the boundaries and spread of the tumors. Besides, they may be used in choosing the targets for stereotaxis biopsy of brain tumors when it is conducted according to the findings of CT. They also increase the informativeness of biopsy.

Astrocytoma↗
PubMed1983

Densitometry of phosphatidylcholine and sphingomyelin in high-density lipoproteins.

We describe the quantitative densitometric determination of phosphatidylcholine (PC) and sphingomyelin (SP) in human serum after precipitation with phosphotungstic acid/MgCl2 and use of thin-layer chromatography. After development, chromatographic plates were charred with methanolic sulfuric acid and MnCl2 and scanned by direct reflectance densitometry in an automated densitometric system interfaced to a basic programmable computing integrator. The method is sensitive enough to detect abnormally low concentrations of PC and SP in high-density lipoproteins. The accuracy of the method was tested either with the Bartlett phosphorus assay or with enzymatic methods for PC and SP; correlations of the described method with the enzymatic determinations were r = 0.93 and 0.88, respectively. Day-to-day precision (CV) for the phospholipid determination was 8.6% for PC and 12.2% for SP. The major advantage of this inexpensive technique is that native plasma or serum or the serum supernate after precipitation can be used without prior delipidation. With this technique serum high-density lipoproteins had PC values of 1.08 (SD 0.32) mmol/L in men (n = 158) and 1.12 (SD 0.37) mmol/L in women (n = 192); similarly, SP values were 0.23 (SD 0.07) mmol/L in the men and 0.23 (SD 0.08) mmol/L in the women. The differences by sex are not significant.

Adult↗
PubMed1995

[Quantitative assessment of blood-aqueous humor barrier permeability using densitometry methods combined with high performance thin layer chromatography].

The paper presents an original method of examining blood-aqueous humor permeability. The examinations were performed on grey rabbits that had been intravenously injected 10% fluorescein solution. Subsequently, at definite time intervals from the moment of the administration, fluid of the anterior chamber was taken in which the amount of aqueous fluorescein permeating to aqueous humor was measured. The measurements were performed using the method of high potency thin layer chromatography (HPTLC) in DS type chambers. Examination results were presented as densitometry, and the area of individual points was counted using a computer programme. This method yielded a diagram quantitatively presenting fluorescein permeation from the blood to the aqueous humor.

Animals↗
PubMed1995

[Quantitative determination of genkwanin in flos Genkwa by TLC-densitometry].

The contents of genkwanin in Flos Genkwa processed in different ways were determined by TLC-densitometry. The result showed that the contents of genkwanin in different samples were 0.128%-0.389% and the rate of recovery was 98.8%, thus offering a reference to the selection of top processing technology.

Chromatography, Thin Layer↗
PubMed1995

[Determination of ursodeoxycholic acid and chenodeoxycholic acid in Chinese medicinal compound preparations by TLC-densitometry].

The contents of ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) in Chinese medicinal compound preparations have been determined by TLC-densitometry. The determination wavelength was 375nm and reference wavelength was 700nm. For UDCA the linear range was 3.0-15.0 micrograms and recovery was 97.2% (RSD = 1.2%), and for CDCA the linear range was 4.0-20.0 micrograms and recovery was 99.3% (RSD = 2.1%).

Animals↗
PubMed1994

Allelic D variants of transferrin in evaluation of alcohol abuse: differential diagnosis by isoelectric focusing-immunoblotting-laser densitometry.

In the diagnosis of alcohol abuse transferrin (Tf) allelic D variants generate false-positive test results for carbohydrate-deficient transferrin (CDT) as assessed by their electrophoretic migration patterns. The predominant Tf C1 allele encodes a protein for which the most prevalent isoform has a pI of 5.4, i.e., four sialic acids and two bound ion molecules. Carriers of allele D encode Tfs with different amino acid sequences, for which the pI is > 5.7, despite their identical iron and carbohydrate composition. We used isoelectric focusing, immunoblotting, and laser densitometry (IEF-IB-LD) to distinguish Tf D variants from CDT. Alcohol abusers carrying the D chi allele tested CDT+; D chi nondrinkers were CDT-. Although normal controls (< 15 g of alcohol per day for 7-10 consecutive days) carrying variants D1, D2, or D chi exhibited abnormal IEF banding patterns, they did not generate false-positive results for CDT. D3 variants expressed isoforms that migrate at the same pI as CDT bands. Thus, IEF-IB-LD yields a highly resolved banding pattern to distinguish most Tf D variants from CDT.

Alcoholism↗
PubMed1994

Densitometry: modern approaches advance an established technique.

Densitometry is an established technique used in most biological research laboratories. Established techniques are often assumed to be stable and therefore not subject to advancement by the application of newer technology. However, when new technology is applied to an established technique, great advances can suddenly occur. Using the latest in laser optics design, semiconductor technology and state-of-the-art software implementation, Molecular Dynamics has developed and recently introduced a new Personal Densitometer SI that has performance capabilities considered impossible only a few years ago. In addition, the entire system can be priced lower than was previously possible.

Biomedical Engineering↗
PubMed1994

[Problems with bone densitometry].

Today, bone density can be measured by different technical methods which show variations in terms of reproducibility, accuracy and sensibility. A crucial parameter is the reproducibility, which differs considerably from method to method. With densitometric methods it is possible not only to evaluate patients at risk getting an osteoporosis but also to establish an individual prophylaxis and therapy by means of highly precise quantitative methods, based on the parameters 'bone density' and 'loss of bone density'. A high bone turnover leads to fast bone loss and, vice versa, fast bone loss, measured by densitometry, is correlated with high bone turnover in postmenopausal women. This allows to establish an individual therapy with antiresorption resp. bone-stimulating agents and the knowledge about a tailored, individual treatment increases patients' compliance and reduces the rate of 'non-responders'.

Aged↗
PubMed1995

[The analysis of the gastric mucosa by computerized densitometry].

An analytical method of histologic imaging of the gastric mucosa by computerized densitometry based on the extraction of components of an image on the basis of its luminous density is described. A group of 10 healthy controls, a group of 10 subjects with gastric ulcer and 10 with duodenal ulcer were included in the study. The method was particularly useful in the identification of atrophic and hypertrophic processes. A decrease was found in the density of parietal and chief cells in atrophic gastritis of the gastric body. In atrophic gastritis of the gastric antrum a decrease was observed in global cell density of the antrum. Patients with gastric ulcer did not present variations versus the control group. In those with duodenal ulcers an increase was observed in the density of surface cell of the gastric body with no variation in the density of parietal and principal cells. This finding challenges the classical concept on the increase in parietal cell mass accompanying duodenal ulcers.

Adolescent↗
PubMed1996

[Laterality differences in ultrasonic densitometry].

The authors discuss lateral differences between heel bones during ultrasonic bone densitometry using the apparatus Achilles Lunar. While the mean values for the whole group are statistically insignificant (162 patients) in different parameters (SOS, BUA, stiffness) in one quarter of the patients the differences between the two extremities are greater than 9% which may be a source of errors when evaluating the state of the skeleton and when subsequently deciding on treatment.

Bone Density↗
PubMed1977

Quantitative determination of drugs by means of densitometry of thin-layer chromatograms. Part 6 Determination of 1-benzhydril-4-allypiperazine dihydrochloride in biological media.

A quantitative method for determination of 1-benzhydril-4-allypiperazine dihydrochloride (As-2) in blood is proposed, based on direct densitometry of t.l.c. plates. The main advantage of the method consists in the fact that it can be applied for determination of As-2 in biological samples in the presence of its metabolites and other components of the investigated samples. The statistical treatment of results obtained from ten analyses shows that the method has no systematic error and the relative percentage error is +/- 8.5%. The lowest concentration which can be determined is 5 microng/1 ml plasma. It has been established that As-2 administered intravenously in the maximally tolerable dose of 22 mg/kg can be detected in the blood after the first min (RF = 0.45). Ten min after application one major metabolite (RF = 0.35) is observed under UV-light. When administered per os in the maximally tolerable dose of 100 mg/kg, As-2 is established in the blood after 15 min while the metabolite mentioned above is detected by the thirtieth min.

Animals↗
PubMed1996

[Foveal cone densitometry in high myopia].

We performed foveal cone densitometry using a modified fundus camera in 17 eyes of 17 normal subjects (age range, 20 to 47 yr, refractive error, +2.0 to -2.5 D) and 15 eyes of 15 high myopia subjects with normal visual acuity (age range, 18 to 46 yr, refractive error, -9.0 to -14.5 D). After fully bleaching, the density of photopigment was measured for 7 minutes by a test spot of 562 nm in wavelength and 1 degree in diameter, focussed on the fovea. Two-way density and the time constant of pigment regeneration were calculated. No significant difference was found in two-way density between the two groups. The time constant in high myopia (161.6 +/- 36.6 sec), however, was significantly increased (p < 0.01), compared with normals (124.0 +/- 28.7 sec). To study the correlation of psychophysical visual function, we performed a photostress recovery test, which revealed a significant delay of the recovery time in high myopia (p < 0.01). These results suggest that a delay in foveal cone pigment kinetics precedes loss of cone cells or chorioretinal degeneration in high myopia.

Adolescent↗
PubMed1997

Selective supplementation of calcaneal ultrasound densitometry with dual-energy x-ray absorptiometry of the spine and femur for population screening.

OBJECTIVE: To determine the limitations on the improvements in the efficacy of screening with ultrasound densitometry of the calcaneus that can be achieved by adding direct-site mineral measurements of the lumbar spine and the femur when the ultrasound t-score is low. SUBJECTS AND METHODS: The author retrospectively analysed data from 2500 women for whom the results of both dual-energy x-ray absorptiometry of the lumbar spine and femur and ultrasonometry of the calcaneus were available. Various ultrasound t-score cut-off values (from 0 to -4.5) were tested to determine changes in sensitivity, specificity, false negatives, false positives and accuracy with and without adding direct-site measurements of the lumbar spine and the femur neck. RESULTS: For this analysis, the addition of direct-site measurement data increases the specificity to 100% for all t-score cut-off values without affecting the sensitivity, thereby improving the accuracy; however, the number of false negatives remains unknown. The number of false negatives decreases as the cut-off value is increased, but with higher cut-off values, greater numbers of subjects would have to be recalled for direct-site measurements of the lumbar spine and the femoral neck, which would entail extra costs. CONCLUSIONS: The accuracy of screening for low mineral content by calcaneal ultrasonometry is improved by recalling subjects for direct-site measurements if their ultrasound t-score falls below some arbitrary value. The cut-off value must be chosen to achieve a balance between the number of missed false negatives that are acceptable in the screening process and the number of subjects recalled for the direct-site study at additional cost. In remote areas, where dual-energy x-ray absorptiometry devices for performing the supplemental measurement are not usually available, the cost of transportation would be another factor.

Adult↗
PubMed1997

Broadband ultrasound attenuation predicts fractures strongly and independently of densitometry in older women. A prospective study. Study of Osteoporotic Fractures Research Group.

BACKGROUND: Quantitative ultrasound of bone is a new radiation-free technique that measures bone mass and may assess bone quality. Retrospective studies have suggested that low-bone ultrasound of the calcaneus is associated with an increased risk for hip and other fractures in older women. OBJECTIVES: To establish the utility of calcaneal quantitative ultrasound of bone for the prediction of fractures and to compare quantitative ultrasound of bone with bone mineral densitometry by performing a prospective cohort study within the Study of Osteoporotic Fractures. SUBJECTS AND METHODS: We studied 6189 postmenopausal women older than 65 years of 4 US clinical centers. Broadband ultrasound attenuation (BUA), a measurement of the differential attenuation of sound waves transmitted through the calcaneus, and bone mineral density of the calcaneus and hip were measured. Subsequent hip and other nonspine fractures were documented during a mean follow-up of 2.0 years. RESULTS: In age- and clinic-adjusted analyses, each SD reduction in calcaneal BUA was associated with a doubling of the risk for hip fractures (relative risk [RR], 2.0; 95% confidence interval [CI], 1.5-2.7); a similar relationship was observed with bone mineral density of the calcaneus (RR, 2.2; 95% CI, 1.9-3.0) and femoral neck (RR, 2.6; 95% CI, 1.9-3.8). After adjustment for bone mineral density of the femoral neck, BUA was still associated with an increased risk for hip fracture (RR, 1.5; 95% CI, 1.0-2.1). Intertrochanteric fractures in particular were strongly associated with a low BUA measurement (RR, 3.3; 95% CI, 2.0-5.5). CONCLUSIONS: Broadband ultrasound attenuation predicts the occurrence of fractures in older women and is a useful diagnostic test for osteoporosis. The strength of the association between BUA and fracture is similar to that observed with bone mineral density.

Aged↗
PubMedDate not supplied

Bone densitometry with L125 in the study of uraemic osteropathy: semeiological signifiance and limitations.

Bone densitometry using I125 is a very easy method of investigation; it may be used repeatedly and simultaneously at different bone levels without distress to patients. The problems involved were those of the value, semeiological significance and possible limitations of this method in the investigation of uraemic osteopathy. These problems were solved successfully in tests carried out on 87 patients of both sexes suffering from various degrees of chronic nephropathy and on chronic haemodialysis patients. The method is reliable: reproducibility tests in normal and uraemic subjects were satisfactory; the indexes remain constant, usually in normal subjects. The parameters are "Bone Mineral Content" and "Bone Index". Trabecular bone is more sensitive than cortical bone, although comparisons between the two types of bone produce interesting data. There are difference dependent on sex. The method which is more sensitive than others enables: 1) Normal and nephropathic subjects, to be distinguished from one another. The latter generally show a lower mineral content and bone index (clinical picture of osteomalacia, osteoporosis, hyperparathyroidism) seldom a higher or a normal one. 2) The same bone sites to be examined over a given period. 3) Treatment of patients to be monitored.

Bone and Bones↗