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At least 1,225 records · Page 68Linked to original sources
PubMed1997

Comparison of the bone robusticity index and bone weight/bone length index with the results of bone densitometry and bone histomorphometry in experimental studies.

In experimental studies of bone in rats, two morphometric indices reflecting bone density have been proposed, the bone robusticity index and bone weight/bone length index. In rats, the bone mineral content (BMC) and bone mineral density (BMD) of a selected bone can be determined using dual-energy X-ray absorptiometry (DXA); bone volume can be measured by histomorphometry and other techniques. This study was undertaken to compare two morphometric indices (bone robusticity and bone weight/bone length) with the results of DXA and histomorphometry. Forty female Wistar rats (100 days old, mean weight 239+/-12 g) were studied: 20 controls and 20 ovariectomized rats (OVX). The morphometric indices and BMD differed significantly (Friedman test) in the overall group of rats; no differences were observed in the control group, but significant differences were apparent in the OVX group (p<0.0001). The morphometric indices correlated more closely with BMC than with BMD; the femur length/ femur weight index had closer correlations than the robusticity index. Nonetheless, both morphometric indices differed significantly from BMD determined by DXA under abnormal conditions, which makes them unreliable for use in these circumstances.

Absorptiometry, Photon↗
PubMed1995

Scanning gel densitometry of amniotic fluid acetylcholinesterase and butyrylcholinesterase: quantification of 'faint-positive' bands in fetal malformations.

The quantification of 'faint-positive' cholinesterases in amniotic fluid was performed in 40 patients with positive acetylcholinesterase (AchE) tests. Fetuses with anencephaly and open spina bifida presented an AchE/butyrylcholinesterase (A/B) ratio of more than 0.3 with clearly dense bands. Fetuses with gastroschisis showed a 'faint-positive' AchE band (A/B < 0.3). In 5 fetuses (1 teratoma, 3 open spina bifida, 1 unaffected) we found faint AchE and butyrylcholinesterase bands.

Acetylcholinesterase↗
PubMed1983

Measurement of systolic and diastolic flow rates in the coronary artery system by x-ray densitometry.

The reliability of a modified videodensitometric and photodensitometric sampling technique for measuring phasic flow rates in the coronary artery system was examined. Electromagnetic flow measurements were performed in a circulatory model with continuous and pulsatile flow and intraoperatively in aortocoronary bypass grafts; cineangiograms were made simultaneously. Based on the front velocities of injected boluses of contrast medium, the densitometric measurement overestimated the electromagnetically measured flow systematically by about 20%. Systolic and diastolic flow rates in aortocoronary bypass grafts and coronary arteries determined from biplane cineangiograms in 34 patients generally revealed the typical pulsatile flow pattern familiar from electromagnetic and ultrasonic flow measurements. Flow velocities in unstenosed coronary arteries were nearly identical before and after branchings of the vessels, whereas the corresponding flow rates were higher in proximal than in distal segments. The identical flow velocities in different branches of the same vessel and the low variability of this parameter in different patients may be a suitable index of the effect of stenoses on coronary arterial blood flow.

Absorptiometry, Photon↗
PubMedDate not supplied

Metabolic bone disease in adults receiving long-term parenteral nutrition: longitudinal study with regional densitometry and bone biopsy.

A syndrome of bone pain and fractures has been described in patients receiving long-term support from parenteral nutrition containing large quantities of aluminium or vitamin D2. Whether this same syndrome occurs in patients supported by current therapeutic regimens is controversial. In this study, bone health was longitudinally evaluated over 7 to 61 months in 14 subjects maintained on long-term parenteral nutrition. The parameters of bone health evaluated included bone mass as measured by single and dual photon absorptiometry and quantitative histomorphometry of bone biopsies. There was a striking heterogeneity in baseline measures of bone health. Mean bone density of parenteral nutrition patients was significantly below expected values on entry into the study at both the distal radius (z score = -0.76 +/- 0.27) and the lumbar spine (z score = -1.17 +/- 0.27). Mean areal density at the forearm was less severely depressed (z score = -0.62 +/- 0.34). The longitudinal changes in bone density and morphology were heterogeneous, with some subjects showing deterioration, others improvement, and still others no change. We conclude that patients already established on parenteral nutrition frequently have osteopenia. The group as a whole did not demonstrate normalization of the osteopenia, but our results also suggest that current parenteral nutrition formulations low in aluminum and vitamin D2 do not necessarily cause worsening of bone health. The etiology of this clinical syndrome merits additional study.

Adult↗
PubMed1994

Effect of beclomethasone dipropionate on bone mineral content assessed by X-ray densitometry in asthmatic children: a longitudinal evaluation.

There is little information on bone turnover in asthmatic children taking long-term treatment with inhaled steroids (ICS). The aim of this longitudinal study was to determine the effects of inhaled beclomethasone dipropionate (BDP) on bone mineral density (BMD), in asthmatic children treated over a period of six months. BMD and growth were studied in two age- and sex-matched groups of asthmatic children. These comprised: 14 asthmatic children (Group 1) who had taken BDP in a dosage of 300-400 micrograms daily through a 145 ml spacer device for at least 6 months (mean age 9.1 yrs); and a control group of 16 age- and sex-matched asthmatic patients (Group 2) not treated with ICS (mean age 9.5 yrs). Mean duration of asthma was 5.7 yrs in Group 1 and 5.5 yrs in Group 2. Vertebral BMD (L2-L4) was measured by dual energy X-ray absorptiometry (DEXA) at the beginning (baseline) of the study and 6 months later. There were no significant differences in the baseline bone mass (mean +/- SEM) between the two groups (0.63 +/- 0.03 and 0.64 +/- 0.02 g.cm-2 in Group 1 and 2, respectively). During the observation period, bone density increased, by 4% (95% confidence interval (95% CI) 2-6) in the control group and by 2.3% (95% CI 0.4-4.2) in the group under BDP treatment, showing no significant influence of the treatment. No difference was found in height velocity evaluated before starting BDP and after 6 months of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1997

Aromatase deficiency in a female who is compound heterozygote for two new point mutations in the P450arom gene: impact of estrogens on hypergonadotropic hypogonadism, multicystic ovaries, and bone densitometry in childhood.

We report on a female who is compound heterozygote for two new point mutations in the CYP19 gene. The allele inherited from her mother presented a base pair deletion (C) occurring at P408 (CCC, exon 9), causing a frameshift that results in a nonsense codon 111 bp (37 aa) further down in the CYP19 gene. The allele inherited from her father showed a point mutation from G-->A at the splicing point (canonical GT to mutational AT) between exon and intron 3. This mutation ignores the splice site and a stop codon 3 bp downstream occurs. Aromatase deficiency was already suspected because of the marked virilization occurring prepartum in the mother, and the diagnosis was confirmed shortly after birth. Extremely low levels of serum estrogens were found in contrast to high levels of androgens. Ultrasonographic follow-up studies revealed persistently enlarged ovaries (19.5-22 mL) during early childhood (2 to 4 yr) which contained numerous large cysts up to 4.8 x 3.7 cm and normal-appearing large tertiary follicles already at the age of 2 yr. In addition, both basal and GnRH-induced FSH levels remained consistently strikingly elevated. Low-dose estradiol (E2) (0.4 mg/day) given for 50 days at the age of 3 6/12 yr resulted in normalization of serum gonadotropin levels, regression of ovarian size, and increase of whole body and lumbar spine (L1-L4) bone mineral density. The FSH concentration and ovarian size returned to pretreatment levels shortly (150 days) after cessation of E2 therapy. Therefore, we recommend that affected females be treated with low-dose E2 in amounts sufficient to result in physiological prepubertal E2 concentrations using an ultrasensitive estrogen assay. However, E2 replacement needs to be adjusted throughout childhood and puberty to ensure normal skeletal maturation and adequate adolescent growth spurt, normal accretion of bone mineral density, and, at the appropriate age, female secondary sex maturation.

Adult↗
PubMed1992

The application of microdosimetry in clinical bone densitometry using a dual-photon absorptiometer.

Experimental microdosimetric methods have been used to determine absorbed dose values for a scanning dual-photon absorptiometer. Absorbed doses within the scanned field have been obtained for three different scanning speeds. For the normal speed setting used clinically, measurements have also been carried out in a water-filled phantom in order to estimate typical patient entrance, exit and midline doses. The results agree well with values obtained using thermoluminescence dosimetry and support the claims of the manufacturers with regard to upper limits placed on patient dose levels. The microdosimetric method enables changes in radiation quality to be followed and comparisons to be made with other low-energy photon fields used in medical diagnosis.

Absorptiometry, Photon↗
PubMed1992

Single- versus dual-energy quantitative computed tomography for spinal densitometry in patients with rheumatoid arthritis.

Lumbar bone mineral density was measured by both single- and dual-energy quantitative computed tomography in 109 patients with rheumatoid arthritis. The results were corrected for the age-related increase in vertebral fat content by converting them to percentages of expected densities, using sex and energy-level specific regression equations obtained in a normal reference population. The percentages of expected density are approximately 10% lower in the single- than in the dual-energy mode, both in the patients with and without prednisone therapy. This difference is statistically highly significant, and is positively correlated with the duration of the disease and with the degree of radiological joint destruction. The data suggest that the vertebral fat content may be increased in patients with rheumatoid arthritis, as a consequence of disease-dependent mechanisms.

Adipose Tissue↗