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PubMed1976

[Measurements of bone mineral concentration ("hydroxylapatite-volume values") and of bone density in vitro and in vivo with a densitometric method using beams of two different energies (author's transl)].

The densitometric method of Rassow-Strüter (1969) using beams of two energies permits separate estimations of bone mineral and connective tissue concentrations in bone; their sum indicates bone density. The value of the method has been examined and the early results of in-vitro and in-vivo measurements are quoted. The former were obtained from pairs of macerated calcanei and vertebral bodies embedded in resin blocks. The in-vivo estimations were concerned with obtaining normal values in healthy children aged four to fifteen years and adults aged 18 to 54 years. Standard deviation, obtained from measurements of four different points of both calcanei in adults was KM 12% for Hydroxylapatite-volume values, and for bone density 14%. The average value for KM for the whole group is 198 mg/cm3 with 17% standard deviation of the single measurements compared with the average. The following-up measurements for children with renal disease do not yet allow final conclusions about the correlation of the clinical aspects of case to the measured bone parameters and their value as independent criteria. For 16 nursing mothers a significantly lower average HA volume value KM = 149 mg/cm3 +/- 21% was found.

Absorptiometry, Photon↗
PubMed2022

Abdominal aortic calcification on lateral spine images captured during bone density testing and late-life dementia risk in older women: A prospective cohort study.

BACKGROUND: Dementia after the age of 80 years (late-life) is increasingly common due to vascular and non-vascular risk factors. Identifying individuals at higher risk of late-life dementia remains a global priority. METHODS: In prospective study of 958 ambulant community-dwelling older women (≥70 years), lateral spine images (LSI) captured in 1998 (baseline) from a bone density machine were used to assess abdominal aortic calcification (AAC). AAC was classified into established categories (low, moderate and extensive). Cardiovascular risk factors and apolipoprotein E (APOE) genotyping were evaluated. Incident 14.5-year late-life dementia was identified from linked hospital and mortality records. FINDINGS: At baseline women were 75.0 ± 2.6 years, 44.7% had low AAC, 36.4% had moderate AAC and 18.9% had extensive AAC. Over 14.5- years, 150 (15.7%) women had a late-life dementia hospitalisation (n = 132) and/or death (n = 58). Compared to those with low AAC, women with moderate and extensive AAC were more likely to suffer late-life dementia hospitalisations (9.3%, 15.5%, 18.3%, respectively) and deaths (2.8%, 8.3%, 9.4%, respectively). After adjustment for cardiovascular risk factors and APOE, women with moderate and extensive AAC had twice the relative hazards of late-life dementia (moderate, aHR 2.03 95%CI 1.38-2.97; extensive, aHR 2.10 95%CI 1.33-3.32), compared to women with low AAC. INTERPRETATION: In community-dwelling older women, those with more advanced AAC had higher risk of late-life dementia, independent of cardiovascular risk factors and APOE genotype. Given the widespread use of bone density testing, simultaneously capturing AAC information may be a novel, non-invasive, scalable approach to identify older women at risk of late-life dementia. FUNDING: Kidney Health Australia, Healthway Health Promotion Foundation of Western Australia, Sir Charles Gairdner Hospital Research Advisory Committee Grant, National Health and Medical Research Council of Australia.

AAC, abdominal aortic calcification↗
PubMed1979

Measuring radiographic bone density and irregularity in normal hands.

This paper describes a method of measuring the radiographic density of the proximal phalanges and metacarpals using a television image analyser. The site for measurement is highly definable and covers the majority of the middle 2/4ths of these bones. Measurements yield two figures; one for mean bone density and one for the density distribution factor (irregularity). Thirty pairs of normal female hands were radiographed and measured. Variations of density and irregularity bone by bone, with age and with dominance are described.

Absorptiometry, Photon↗
PubMed1976

Bone density measured by photon scattering. II. Inherent sources of error.

The origins of inherent sources of error in results of measurements of bone density by a photon scattering technique are described and their effects are predicted theoretically. The predictions are confirmed experimentally. The prime source of error is multiple scattering. A procedure has been developed to correct the observed densities for effects of multiple scattering.

Bone Diseases↗
PubMed1978

Effect of chronic centrifugation on bone density of the dog.

Sixteen male Beagle dogs, 293 to 509 days old, were exposed almost continuously for 3 months to 2.0 G on a 7.9m radius centrifuge. The dogs were maintained on the centrifuge by means of a specially designed, automated waste disposal and life support system. Bone density was measured by a 125I Profile Scanner in the anterior, medial posterior and lateral cortex of the femoral mid-shaft. As compared to mean density in the femora of normal gravity controls, centrifuged dogs showed a 0.8% (P less than 0.05) lower mean linear absorption in their femora. However, the regression of density on the square-root of cross-sectional area/pi differs very significantly in the animals living at earth gravity and those living at hypergravity. Thin hypergravic bones are denser, thick hypergravic ones are less dense than the corresponding ones of normal gravity controls.

Animals↗
PubMed1977

Effect of chronic centrifugation on bone density of the rat.

Alterations in density of the femur of female Sprague-Dawley rats exposed to chronic centrifugation of 2.76 G for 810 days were studied. The density was measured by photon absorptiometry, using a 125I Profile Scanner. The photon absorption measurements were taken: (1) on bone sections from the midshaft of the femur in the anterior, posterior, medial and lateral cortex with the beam path parallel to the shaft axis, and (2) on the femur near the midshaft with the beam path perpendicular to the shaft axis. The latter were correlated with the cross-sectional area in the midshaft. Compared with femora of age-matched rats (age controls) and of rats having body masses comparable to the centrifuged group (weight controls), kept under earth gravity, the chronically centrifuged animals showed no average no significant differences in photon absorption (density) in the four positons in midshaft. The absorption measurements perpendicular to the shaft axis in all groups differ significant differences between the centrifuged group and the control groups. When cross-sections of equal size are compared, the density of the rat femora is clearly higher in the centrifuged animals than in the control groups. In contrast, the age and weight controls do not differ significantly in density. The results suggest that the increased stress in the rat femora due to centrifugation is reflected in an increased bone density.

Absorption↗
PubMed1978

[Bone density measurements by computer tomography (author's transl)].

The suitability of the E.M.I. mark I computer scanner for carrying out bone densitometry has been tested, using the forearm. Within the region of interest there was an almost linear relationship between CT densities and the concentration of the bone equivalent substance K2HPO4. By means of a special computer programme, the spongiosa and cortex of both forearm bones could be analysed quantitatively. The reproducibility of the results (coefficient of variation 5%) was similar to that of other procedures in current use. The advantage of the method lies in the fact that it is possible to estimate the spongiosa and cortex separately. Investigations on patients with normal bones have shown that senile demineralisation affects the cortex most severely. On the other hand, in renal osteopathies of chronically dialysed patients, demineralisation in the forearm predominantly involves the spongiosa.

Absorptiometry, Photon↗
PubMed1977

[25-hydroxy vitamin D deficiency with reduction of intestinal calcium absorption and bone density in chronic alcoholism].

Plasma levels of 25-hydroxycalciferol (25-OH-D), 47-calcium intestinal absorption, bone mineral content and the biologic parameters of phospho-calcium metabolism were studied in 30 chronic alcoholics, 15 with Laennec's cirrhosis (group A) and 15 without (group B). These patients were compared with 27 normal subjects. In group A, the mean 25-OH-D plasma level was 23.7 +/- SD 18.5 microgram/l and in group B 35.2 +/- SD 21.8 microgram/l. These mean levels were lower than those of the control group, which were 57.2 +/- SD 22.5 microgram/l (p less than 0.001). The mean value of the 47Ca intestinal absorption, measured as the percentage of the ingested dose per litre of plasma and multiplied by the body weight, was also significantly lower in group A, which was 140 +/- SD 47 (p less than 0.01), and in group B, which was 145 +/- SD 69 (p less than 0.05), compared with the normal subjects whose average was 182 +/- SD 45.6. Similarly, the total plasma calcium was low: 1.99 +/- SD 0.24 mmol/l in all the alcoholics, while that of the control group was 2.22 +/- SD 0.18 mmol/l (p less than 0.001). For the 30 chronic alcoholics there was a positive correlation between 25-OH-D and 47Ca intestinal absorption, (r = 0.484; p less than 0.004). This suggests that in chronic alcoholism the deficiency of 25-OH-D induces a diminution of the intestinal absorption of calcium which, in the long term, can result in bone demineralization evidenced in the patients studied by a bone mineral content lower than normal (p less than 0.001).

Adult↗