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Results for “Population Density--determinants”

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PubMed1990

The impact of osteophytic and vascular calcifications on vertebral mineral density measurements in men.

To evaluate the influence of extravertebral calcification on spinal bone density determinations, we measured lumbar vertebral density in 71 hospitalized and 58 normal men using dual photon absorptiometry. The extent of vascular and osteophytic calcification was graded from lateral lumbar radiographs. Fifty-five (43%) of the subjects had identifiable osteophytes, and 86 (67%) had vascular calcifications. Despite similar ages and weights in subjects with and without ostephytes, those with osteophytes had greater spinal density (1.34 vs. 1.17 g/cm2; P less than 0.001), and there was a strong correlation between osteophyte severity and spinal density (r = 0.41; P less than 0.00001). Proximal femoral density was not different in those with and without osteophytes. The distribution of osteophytes in this population was not random, and as a result, the presence of osteophytes obscured the the relationship of bone density to age as well as the comparison of hospitalized to normal men. Vascular calcification had a minimal effect on vertebral density. In summary, osteophytic calcification exerted an important influence on the measurement of spinal bone density in men. This effect should be considered in both clinical and research applications of integral vertebral density measures.

Absorptiometry, Photon↗

PubMed2005

Evaluation of quantified contrast-enhanced color and power Doppler ultrasonography for the assessment of vascularity and perfusion of naturally occurring tumors in dogs.

OBJECTIVE: To investigate subjective and computerized methods of evaluation of color Doppler (CD) and power Doppler (PD) ultrasonographic images (obtained before and after administration of contrast medium) for quantitative assessment of vascularity and perfusion of various naturally occurring tumors in dogs. SAMPLE POPULATION: 34 tumors in 34 dogs. PROCEDURE: Tumors in dogs were examined via CD and PD ultrasonography before and after i.v. injection of a microbubble contrast agent (pre- and postcontrast examinations, respectively). Images were digitized for subjective assessment of vessel density and vascular pattern and computer-aided assessment of parameters of vascularity (fractional area [FA]) and perfusion (color-weighted FA [CWFA] and mean color-weighted FA [CWFA] and mean color level). RESULTS: With both analysis methods, more vessels were identified in precontrast PD ultrasonographic images than in precontrast CD ultrasonographic images. Moreover, compared with values for precontrast PD ultrasonography, FA, CWFA, and mean color level were higher for postcontrast PD ultrasonography. In postcontrast images, there was a significant association between vessel densities determined through subjective and computerized assessments. Although sample size was small, vascularity of squamous cell carcinomas was significantly greater than that of other tumor types. Ten of the 19 softer than issue that sarcomas had low vessel density with minor contrast enhancement. With increasing gross tumor volume, FA and CWFA decreased for all Doppler ultrasonographic methods. CONCLUSIONS AND CLINICAL RELEVANCE: Higher values of the ultrasonographic parameters representing vascularity and perfusion of tumors in dogs were determined via PD ultrasonography after administration of contrast medium than via PD or CD ultrasonography without administration of contrast medium.

Animals↗

PubMed2001

[Bone mineral density determination by osteosonography in healthy children and adolescents: normal values].

BACKGROUND: Osteoporosis is a frequent health problem in adults. Optimization of bone mass acquisition during childhood and adolescence may play a major role in the prevention of this disease. Osteosonography is a recent technique for measuring bone mineralization without exposing the patient to radiation. OBJECTIVES: To measure bone mineral density using osteosonography in healthy Spanish Caucasian children and adolescents in order to determine normal values. METHODS: We performed a cross sectional study of 829 healthy child and adolescent volunteers (360 girls and 469 boys) randomly selected from the urban area of Pamplona in Navarre (Spain). Ages ranged from 6 to 18 years. ADBM Sonic 1200 ultrasound densitometer from IGEA was used. Daily calcium dietary intake and amount of physical activity were recorded. RESULTS: Cross sectional standards for Ad-SOS are presented. Ad-SOS did not significantly change between the ages of 6 and 9 years in girls or until the age of 10 years in boys. From the ages of 10 to 14 years, Ad-SOS values were higher in girls than in boys. After the age of 14 years, no significant differences were found. No correlation was found between calcium dietary intake, amount of physical exercise or bone mineralization values. CONCLUSIONS: Measurement of Ad-SOS by osteosonography is an easy, fast and inexpensive method for measuring bone mineral density in children and adolescents without exposing them to radiation. It can be used in the pediatric population to detect early alterations in bone mineralization.

Adolescent↗

PubMed2003

A rapid, automated flow cytometric method to measure activated degranulated platelets by density determination.

Platelet activation is reported to correlate with acute coronary syndromes. A platelet analysis method on the ADVIA 120 Hematology System provides rapid analysis of platelet density, reported as mean platelet component (MPC) concentration, utilizes routine hematology specimens, requires no pre-treatment, and thirty seconds to generate results. Sub-populations of platelets separated by density gradients showed excellent correlation with the ADVIA 120 MPC parameter (r = 0.997). Platelet activation induced by thrombin treatment resulted in a shift of platelets into the lowest density fraction (d</=1.068 g/mL) with a corresponding reduction in MPC from 24.7 to 20.6 g/dL, N = 4 subjects (p < 0.004). There was also excellent correlation between expression of CD62P measured by fluorescence flow cytometry and the ADVIA 120 Hematology System MPC values (r = 0.85). These results indicate that the ADVIA 120 MPC parameter may be a useful new test for assessing activated platelets and platelet density.

Automation↗

PubMed1978

[Fly density determination in cow-sheds].

Considering the tropical conditions of the Republic of Cuba and the usually applied methods of measuring fly-density, a photographic method was developed and tested basing on the experience of the SCUDDER-fly-grill method. In this method the flies are photographically counted in defined areas of 0.25 m2 of extension, which are determined according to the concrete conditions in the animal production units. An index of the fly density (in flies per m2) is calculated. The exact comparison of different animal production units will be obtained by the selection of the defined areas for the photographic counting, always the equal times for measuring, and the consideration of the situation in the production cycle.

Animals↗

PubMedDate not supplied

[Statistics of bone mineral density determined with a double-energy X-ray equipment].

This study was aimed at analyzing the bone mineral density values measured in a non-selected sample of more than 2,500 Italian women from the Treviso province. The subjects were divided into nine 10-year age groups. The figures (%) in each age group are presumed to be constant over time, although arranged on a Gaussian curve because of high interperson variability. The tables with normal rates, made on the basis of the data obtained, represent the reference parameters to evaluate bone mineral content in all the women referred to our hospital for this particular reason. The tables mirror, with the highest possible accuracy, the typical figures of the female population in Treviso, inasmuch as those findings were obtained from a statistically homogeneous sample (that is, uniform in nature). On the other hand, slight differences were observed relative to the figures of population segments other than our study population. Since the risk of bone fractures is related to how quickly bone mass decreases over time, seriated measurements should be compared with the normal curve which is similar in women of every race. Thus, the tables indicate probable normality whenever the figure found for one woman falls within the normal age and race ranges the patient belongs to. If the patient belongs to a population with different lifestyle and environmental factors, the tables are but indicative; for more accurate evaluation, a late control should be made. On the contrary, if rates are markedly lower than normal, a control should be made much sooner. Moreover, the correlations between the bone density rates found in different bone segments indicate the very poor chance of predicting fracture risk at a different point from the examined one. This means that the body areas at greater risk must be studied separately. Finally, we stress the reason why it is impossible to obtain the very same information from bone mineral content measurements on the whole skeleton and how these data can be used.

Absorptiometry, Photon↗