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Biomedical subjects

J A Raymakers

Publications and source records attributed to J A Raymakers.

At least 37 records · Page 2Linked to original sources
PubMed1990

Assessment of osteoporotic spine deformity. A new method.

For the objective assessment of the severity and progression of osteoporotic deformities of the spine, a mathematical model has been developed which permits evaluation of a single set of radiographs of the spine without reference to absolute values of vertebral height. The model was based on measurements of anterior, central and posterior heights of the vertebrae Th4 to L5 of 50 subjects, aged 20 to 50 years, without a history or radiologic signs of osteoporosis or other metabolic bone disease and without traumatic deformities. The model follows a simple sinusoidal function which describes the general form of the spine, adapted to the individual's height and build. A spine fracture index (SFI) is produced and the method allows calculation of the total number of vertebral deforming events (VDE), manner. The method has been used prospectively in 178 spine radiographs of 109 subjects (60 healthy early postmenopausal women and 49 with osteoporosis). Sensitivity and specificity of SFI in identifying osteoporotic patients were 94 and 88% respectively. In all 109 persons, densitometry of the spine was performed by dual photon absorptiometry at the same time. In the osteoporotic patients the examination was repeated once or twice during fluoride therapy for osteoporosis. The SFI and the total score of VDE and VDS correlated significantly with lumbar bone mineral content (r = -0.38 P less than 0.001). The method offers the advantage of being objective, not dependent on projection errors, and adaptable to the shape of the individual spine.

Adult↗
PubMed1990

The value of local 99mTc(Sn)-MDP bone to soft tissue uptake ratio in osteoporosis, before and during fluoride therapy.

The reproducibility and diagnostic value of local bone to soft tissue uptake ratio of 99mTc(Sn)-MDP as a bone tracer was examined in a prospective study in 35 patients who were under investigation and/or treatment for postmenopausal osteoporosis. The ratio of tracer uptake in the second lumbar vertebra (L2) and both femoral shafts was calculated from the number of counts in suitable regions of interest. Results obtained with settings and calculations in the routine practice were compared to the results obtained by revision of all raw data in one run by one person. The results were compared to the serum alkaline phosphatase activity (AP) and to local bone mineral mass as determined by dual photon absorptiometry (DPA). In 15 patients serial measurements during fluoride therapy were also compared to serum osteocalcin values and to bone histomorphometric data. The precision error of the calculation of uptake ratios from raw counts (including selection of region of interest) was 13.9% for the femoral shaft and 14.7% for L2. The mean difference between left and right femoral shaft in individuals was not significant and its variance was small P greater than 0.1). There was a weak but significant linear correlation between local uptake ratio in the spine and AP in the total material (r = 0.328 P less than 0.01). However, changes in local uptake ratio during therapy with fluoride in 15 patients were too small to be of any value and did not correlate with changes in alkaline phosphatase or osteocalcin or trabecular surface covered with osteoblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Relation of axial bone mass to habitual calcium intake and to cortical bone loss in healthy early postmenopausal women.

A group of 60 healthy early postmenopausal women participating in an ongoing study on the effect of habitual calcium intake on the rate of cortical bone loss at the radius, were subjected to additional skeletal measurements at the lumbar spine and femoral neck. The women were between 58 and 64 years of age, and 3 to 10 years postmenopausal. No correlations were found between habitual calcium intake (range 560 to 2580 mg/day) and either bone mineral content of the radius, the lumbar spine and the femoral neck, or spine deformity index. Body mass index was found to be positively correlated with bone mass indices of the radius (decrease of BMD and BMD) and femoral neck (BMC), but not with of the lumbar spine (BMC, BMD and SDI), even after adjustments had been made for confounding factors. Although the rate of cortical bone loss at the radius correlated significantly with bone mineral content of lumbar spine and femoral neck, the error in predicting bone mass of the lumbar spine or the femoral neck from longitudinal measurements of cortical bone at the radius was high. The rate of cortical bone loss did not correlate with the spine deformity index. We conclude that in healthy women in early menopause, the bone mineral content of both the appendicular and the axial skeleton are not influenced by habitual calcium intake. A higher body mass index has a protective effect on the appendicular skeleton but appears to be less protective to the axial skeleton. Longitudinal measurements of cortical bone mass are of limited value to predict bone density of the appendicular and axial skeleton.

Absorptiometry, Photon↗
PubMed1990

No effect of APD (amino hydroxypropylidene bisphosphonate) on hypercalcemia in patients with renal osteodystrophy.

Hypercalcemia, due to autonomous functioning of the parathyroids following long standing secondary hyperparathyroidism, is a well known complication in patients with renal osteodystrophy, which can on most cases be treated by parathyroidectomy only. While patients with renal osteodystrophy react favorably to supplementation of active vitamin D metabolites to prevent or reverse renal osteodystrophy, the use of these drugs is bound to result in greater hypercalcemia in those patients who are already hypercalcemic. The question rose if the bisphosphonate amino hydroxypropylidene bisphosphonate (APD) would decrease plasma calcium concentration sufficiently in order to create room for the use of vitamin D to cure the osteomalacia component of the osteodystrophy and simultaneously block the excessive bone resorption. Therefore, five patients with renal osteodystrophy and hypercalcemia were treated for up to 9 months with APD. Three of them, who were on chronic hemodialysis, received 15 mg APD i.v. 3 times a week, the 2 other patients with severe renal failure received 200 mg APD orally. Ionized calcium in plasma did not decrease. Histological investigation of bone samples, obtained before and after therapy, showed an increase of fibrous tissue and a remarkable increase in the number of osteoclasts or osteoclast-like cells not only along the bone-margin, but mainly within the bone-marrow. We conclude that in patients with renal failure with hypercalcemia, APD in the doses used had no effect on plasma calcium level, but caused a striking change in bone histology. Although the consequences of these findings are not yet clear, they do not seem to indicate improvement of bone structure.

Adult↗
PubMed1990

[Hypercalcemia in the elderly].

The symptoms which are caused by hypercalcemia are variable and unspecific. In the elderly the functional capacity of homeostatic mechanisms is less than in young people and at the same time the prevalence of diseases which may cause hypercalcemia is greater. One should be aware of the possibility of hypercalcemia in patients presenting vague gastrointestinal and/or psychiatric complaints or symptoms. The prevalence of hypercalcemia in elderly women may well be 3%. Hypercalcemia leads to renal loss of salt and disturbances of renal function. An increasing inability to excrete the calcium overload is the result. Only in primary hyperparathyroidism renal function remains generally normal and moderately increased calcium levels may exist for years without serious consequences. Important causes of hypercalcemia in the elderly are hyperthyroidism, malignant disease and abrupt immobilization with previously elevated skeletal remodelling activity. Thiazide diuretics may precipitate the hypercalcemic state. Diagnosis is relatively simple and is based on a limited package of laboratory tests. Treatment should always begin with the restoration of the extracellular fluid volume. This is followed by inhibition of bone resorption by means of bisphosphonates or corticosteroids and treatment of the underlying disease.

Aged↗
PubMed1989

No short-term effects of 24,25-dihydroxycholecalciferol in healthy subjects.

Seven healthy volunteers were given 25 micrograms of 24,25-DHCC for one week to study the effects on calcium and bone metabolism. Mean plasma 24,25-DHCC concentration increased from 2.2 +/- 1.7 micrograms/l to 10.8 +/- 6.1 micrograms/l (p less than 0.001). No significant change was seen in the fasting plasma concentrations of Ca, Ca++, PTH and alkaline phosphatase activity and in urinary excretion of calcium and hydroxyproline and in tubular reabsorption of phosphate. The area under the curve for plasma ionized calcium concentration and urinary excretion of calcium during a standard calcium infusion of 10 mg/kg of Ca in 2 h did not change by 24,25-DHCC. We conclude that in healthy subjects no effect of 24,25-DHCC on the steady state parameters of calcium and bone metabolism, on renal calcium handling and on the handling of an intravenous calcium challenge by the homeostatic system could be demonstrated.

24,25-Dihydroxyvitamin D 3↗
PubMed1988

Bone mineral content of the forearm in healthy Dutch women.

Single energy photon absorptiometry is a reliable technique for assessing the bone mineral content (BMC) of cortical bone in the forearm. It can also be used for BMC measurement in the ultradistal part of the forearm, where there is a considerable proportion of trabecular bone. The results of a BMC survey at both sites in healthy Dutch women, aged 26-75 yr, are reported, and the differences and changes with age are discussed. The technique offers possibilities for a rational screening programme in post-menopausal women, because of its high precision, low radiation dose, speed and low cost. The validity of the ultradistal measurement for the detection of abnormally fast bone mineral loss from trabecular bone in the individual patient has yet to be proven.

Adult↗
PubMed1988

Acute changes in calcium and bone metabolism during methylprednisolone pulse therapy in rheumatoid arthritis.

Corticosteroids (CS) decrease bone formation and enhance bone resorption and this can lead to osteopenia. Bone metabolism was studied during the administration of huge amounts of CS (1000 mg methylprednisolone) over a short period of time in 10 patients with persistently active rheumatoid arthritis. The effects could be divided into those occurring within 24 h: (a) a decrease in bone resorption (urinary excretion of calcium and hydroxyproline) and bone formation (alkaline phosphatase); (b) a decrease in renal excretion of calcium; (c) an increase in concentration of serum 1,25-dihydroxy-cholecalciferol and those secondary effects arising after 24 h; (d) a decrease in serum calcium due to the decrease in intestinal Ca absorption and the decrease in renal tubular reabsorption of Ca; (e) an increase in serum PTH concentrations. In a previous study it was found that these changes normalized within a few days after completion of the CS treatment.

Adult↗
PubMed1987

Responders and non-responders after fluoride therapy in osteoporosis.

Patients with osteoporosis were treated for two years with sodium fluoride. Fifteen received sodium fluoride in capsules, 56 in enteric coated slow release tablets (Ossin) and 20 in enteric coated tablets (Procal). Seven women treated with Procal were also treated with oestrogens. All patients had a calcium intake between 1000 and 2000 mg/day, used dihydrotachysterol for vitamin suppletion and were advised to exercise. Non-responders were arbitrarily defined as those who had an increase in serum alkaline phosphatase less than 10 U/l, those who had no increase in bone mineral content measured with CT in L4 and those who got a femoral neck fracture during the period of therapy. In the overall group of 91 patients 20% were non-responders based on a serum alkaline phosphatase increase less than 10 U/l. Based on the changes in bone mineral content 40% were non-responders during the first year of treatment, 45% during the second year and 23% over the first plus second year. The impression is that patients with a femoral neck fracture have a higher increase in serum parathyroid hormone concentration than patients without fractures. The urinary excretion of fluoride has a better predictive value than the change in serum alkaline phosphatase concentration for the prediction of an increase in bone mineral content.

Aged↗
PubMed1987

Monitoring fluoride therapy in osteoporosis by dual photon absorptiometry.

Dual photon absorptiometry (DPA) was used to evaluate changes in bone mineral mass in 108 osteopenic patients. Ninety were treated with fluoride and 18 served as controls. All osteopenic patients and 9 of the controls took calcium and vitamin D supplements. In 16 women estrogens were combined with the fluoride therapy. Seven patients received prednisone. Significant positive changes in bone mineral mass in the lumbar spine could be demonstrated over a mean observation time of 14-15 months in all groups treated with fluoride but not in the control group. The average increase in bone mineral mass in the lumbar spine (L2, L3 and L4 combined) ranged from 3.57% +/- 1.42% (sem, p less than 0.05) in women on fluoride to 10.36% +/- 3.17% (p less than 0.01) in men and 10.18% +/- 2.39% (p less than 0.001) in women on estrogen and fluoride. Changes in bone mineral mass in femoral necks (left and right combined) and femoral diaphysis were not significant. In the control group no significant changes were observed (lumbar spine: -1.68% +/- 1.75%, femoral necks -0.09% +/- 3.3% and femoral diaphysis -2.32% +/- 2.40%). It is concluded that a positive effect of fluoride on trabecular bone in the spine can be demonstrated with DPA on a group basis when data processing is done in a uniform way by a single observer. Its longitudinal use in individual patients necessitates a series of measurements to overcome the analytical error.

Adult↗
PubMed1986

Fracture prevalence and bone mineral mass in osteoporosis measured with computed tomography and dual energy photon absorptiometry.

In 174 adults presenting with backache, bone densitometry was performed on the lumbar spine, both femoral necks, and one femoral shaft employing dual energy photon absorptiometry (DPA); in 112 of these, densitometry was undertaken on L4 using single energy quantitative computer assisted tomography (CT). Radiographs of the spine were obtained in all patients and those with known or suspected malignant disease were excluded. The subjects were divided into two groups according to the presence (n = 128) or absence (n = 44) of signs of vertebral collapse or compression. The predictive value of the densitometric results for the presence of vertebral fractures was calculated and used as an estimate of fracture risk. While CT showed somewhat higher predictive values than DPA of the spine or combinations of DPA results from spine and femoral necks, the difference was not significant. It is concluded that with both CT and DPA the probability of the presence or absence of fracture can be raised to 75-80% when the probability prior to the investigation is 50% and when the threshold values of the measurements are chosen so that their sensitivity and specificity are about equal.

Adult↗
PubMed1985

Treatment of renal osteodystrophy in children with dihydrotachysterol and 24,25-dihydroxyvitamin D3.

The effect of administration of 25 micrograms 24,25-dihydroxyvitamin D3 (24,25(OH)2D) combined with dihydrotachysterol (DHT2) on clinical, radiological, biochemical and bone histological parameters was assessed in ten children on chronic hemodialysis. Eight children had been treated with DHT2 prior to administration of 24,25(OH)2D. Addition of 24,25(OH)2D to the treatment resulted in a decrease in serum calcium values. Therefore higher doses of DHT2 were required to maintain serum-calcium levels between 2.4-2.8 mmol/l. Administration of 24,25(OH)2D did not modify the quality of bone, but histomorphometric investigation did show a significant reduction of the surface percentage of bone trabecula, in the iliac crest, covered with osteoclasts (oc%). Following the administration of 24,25(OH)2D an increase in bone mineralization was shown by X-rays of the wrists and measured by dual photonabsorptiometry. Addition of 24,25(OH)2D to the DHT2 treatment resulted in an increase in serum concentration of 24,25(OH)2D and a decrease in DHT2 levels. The present study suggests that administered 24,25(OH)2D interferes with DHT2 metabolism and increases DHT2 tolerance. Increased bone mineralization may be related to 24,25(OH)2D, a higher dose of DHT2 or both.

24,25-Dihydroxyvitamin D 3↗