Biomedical subjects
Publications and source records attributed to F Ring.
Methods of bone mineral density measurement are presented. Radiological photogrammetry, single photon absorptiometry, dual photon absorptiometry and dual energy X-ray absorptiometry are described. Mode of work of densitometers and their characteristics ares presented. Modern development of densitometric equipment and possible application in diagnosing of osteoporosis is discussed.
Peak bone mass is an important determinant of the risk of osteoporotic fracture, and preventive strategies against osteoporosis require a clear understanding of the factors influencing bone gain in early life. We report a longitudinal study aiming to identify the relationships between childhood growth, lifestyle, and peak bone mass in women. One hundred and fifty-three women born in a British city during 1968-1969 were traced and studied in 1990. Data on their growth in childhood was obtained from linked birth and school health records; current bone mineral measurements were made by dual X-ray absorptiometry. There were statistically significant associations between weight at 1 year and BMC (but not BMD) at the lumbar spine (r = 0.32, p < 0.01) and femoral neck (r = 0.26, p < 0.01). These remained significant after adjusting for current weight. There were also strong relationships between childhood height measurements and adult BMC at the two skeletal sites. Physical activity was the major lifestyle determinant of BMD after allowing for body build. We conclude that infant growth and physical activity in childhood are important determinants of peak bone mass in women. Growth primarily determines the size of the skeletal envelope, and its trajectory is established by age 1 year. Activity, in contrast, modulates the mineral density within the skeletal envelope and may contribute to the consolidation of bone following the end of linear growth.
OBJECTIVES: To determine whether significant reduction in bone mass is detectable in early disease in patients with rheumatoid arthritis (RA) and to examine the possible influences of disease activity and physical disability on bone mineral density (BMD) of the lumbar spine (LS) and femoral neck (FN). METHODS: LS and FN BMD values were measured and Z scores determined in a cross-sectional study of 104 patients with RA of less than five years duration. BMD values were also compared between a subgroup of 64 patients and a normal control group matched for age, sex, menopausal status and body mass. BMD values and Z scores were correlated with disease activity, measured by the Stoke Index, disability, measured by HAQ score, and disease duration. RESULTS: Premenopausal female patients with RA had significantly reduced mean FN Z scores (-0.62, 95% CI -0.30 to -0.94) which correlated with HAQ scores (Rs 0.358, p = 0.05) and age (Rs 0.397, p = 0.03). There were no significant changes of BMD in males or postmenopausal females. Disease duration and disease activity did not correlate with BMD changes. CONCLUSION: BMD is reduced in premenopausal female patients with early RA possibly related to the attainment of peak bone mass. No significant reduction of BMD was found in males or postmenopausal females with early disease. Physical disability but not disease activity appears to play a role in the reduction of FN bone mass.
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This study of 20 patients with monoclonal gammopathy (17 patients with multiple myeloma and 3 patients with Waldenström's syndrome) showed a decreased platlet aggregation induced by ADP and collagen, a reduced platlet retention and a prolonged bleeding time in 25% of the cases in comparison with 30 age- and sex-matched healthy controls. Using Wu and Hoak's technique as increased number of reversible platelet aggregates was observed. There was no relationship between the parameters of primary haemostasis and protein analysis. A disturbed mechanism of primary haemostasis is the main factor responsible for the bleeding diathesis in patients with monoclonal gammopathy.
In eight chronically haemodialysed patients a significant increase of circulating platelet aggregates (method of Wu and Hoak) was observed immediately after starting haemodialysis. The number of aggregates decreased at the end of haemodialysis reaching the starting values after 360 min. The platelet interaction with the dialysis membrane surface might cause this phenomenon. Anticoagulation with heparin alone was insufficient in preventing aggregate formation during haemodialysis.
Morphological control of Moncada's bioassay for prostacyclin (PG I2) activity measurement shows that the activity depends not only on endothelium, but in important amounts on subendothelial tissue too. Therefore, it can be concluded that platelet thrombus formation after endothelial cell injury does not depend only on the PG I2-producing ability of the tissue.
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Platelet retention was investigated using a standardized technique with a glass pearl column in 18 patients with malignant thyroid disease treated by thyroidectomy before and after high-dose radioiodine treatment (80 or 150 mCi). As compared with the normal controls platelet retention was significantly lower in 13 hypothyroid patients in whom thyroidectomy had been undertaken at least 6 months previously and hormone substitution therapy had been interrupted 3 weeks before the period of investigation. The remaining 5 patients, studied about 18 days following thyroidectomy, were euthyroid and displayed platelet retention values within the lower limits of the normal range except for one patient with markedly reduced values. Thyroid substitution therapy with synthetic preparations induced recovery of platelet retention in both groups examined over a 4 week period, the increase being highly significant in the group of hypothyroid patients. A transient increase in platelet retention was observed 24 hours after a therapeutic dose of radioiodine, and initial values being regained after a further 24-hour period. This phenomenon was found in both, the euthyroid and hypothyroid group, however, it was more pronounced in the latter patients. Our results indicate a dependence of platelet retention on thyroid hormone concentration. The observed transient increase after radioiodine may be due to a radiation effect.
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The authors have correlated the findings of thermography and radiology in some inflammatory lesions. The two investigations are complementary. Thermography demonstrates changes of vascularity in the acute phase of a lesion whereas radiology is of value in showing structural changes.
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Patients with severe ankylosing spondylitis of long duration often have spinal osteoporosis secondary to ankylosis and immobility. Bone mineral density of defined regions of the lumbar spine, femoral neck, and carpus was measured in 25 men who met accepted diagnostic criteria for ankylosing spondylitis but had early disease, with normal mobility and no, or very minor, radiological evidence of lumbar spine involvement. Compared with age-matched male controls, patients with ankylosing spondylitis had a significantly lower hydroxyapatite density in the lumbar spine (mean [SD] 0.82 g/cm2 [0.12] vs 0.91 g/cm2 [0.11]) and in the femoral neck (0.83 g/cm2 [0.11] vs 0.92 g/cm2 [0.11]). There was no significant difference in carpal bone mineralisation density. The pattern of bone loss in these patients indicates early loss of trabecular bone in ankylosing spondylitis, possibly from a systemic cause, but biochemical indices of calcium turnover were similar in patients and controls.