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Biomedical subjects

J E Compston

Publications and source records attributed to J E Compston.

At least 163 records · Page 9Linked to original sources
PubMed1984

Bone histomorphometry and vitamin D status after biliopancreatic bypass for obesity.

Bone histomorphometry and vitamin D status were investigated in 41 patients studied 1-5 yr after partial or total biliopancreatic bypass. Metabolic bone disease, characterized by defective mineralization, decreased bone formation rate, and increased surface extent of resorption, was present in 30 patients (73%). Nine patients (22%) were hypocalcemic, but serum 25-hydroxyvitamin D concentrations were normal in all 41 patients. We conclude that metabolic bone disease is common after biliopancreatic bypass and usually occurs in the absence of simple vitamin D deficiency. The pathogenesis of the bone disease is unclear.

Adolescent↗
PubMed1983

Value of the history in diagnosis of histological osteomalacia among Asians presenting to the NHS.

A questionnaire screening for osteomalacia was used to obtain histories from 53 consecutive Asian patients referred to a gastroenterology unit. 15 of the patients were found to have osteomalacia on subsequent histology. The questions that best distinguished between osteomalacic and non-osteomalacic patients were identified by discriminant analysis. These questions were used to derive discriminant functions by which a second sample of 45 Asian patients presenting to other parts of the National Health Service were classified as osteomalacic or non-osteomalacic. Bone histology showed false-negative and false-positive rates of 10% and 11%; the predictive value of the negative result was 97%. A short questionnaire would be a cheaper and more convenient method than biochemical screening for osteomalacia case-finding among Asian patients presenting to the NHS.

Alkaline Phosphatase↗
PubMed1983

Vitamin D.

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Enterohepatic Circulation↗
PubMed1983

Reduced plasma half-life of radio-labelled 25-hydroxyvitamin D3 in subjects receiving a high-fibre diet.

1. The plasma disappearance of 3H-labelled 25-hydroxyvitamin D3 (25(OH)D3) was studied in healthy volunteers on normal and high-fibre diets, using 3H-labelled tracer doses given intravenously. 2. The mean (+/- SEM) plasma half-life in the high-fibre-diet group was 19.2 +/- 1.7 d, which was significantly shorter than in the group on normal diets (27.5 +/- 2.1 d, P less than 0.01). 3. This finding suggests that a high-fibre diet leads to enhanced elimination of 25(OH)D3 by an action within the intestinal lumen. This may involve interference with an enterohepatic circulation of the metabolite, perhaps by binding of 25(OH)D3 to dietary fibre. 4. The reduced plasma half-life of 3H-labelled 25(OH)D3 associated with a high-fibre diet may explain the development of vitamin D deficiency in Asian immigrants with normal exposure to u.v. light.

Adult↗
PubMed1982

Histomorphometric analysis of bone biopsies from the iliac crest of normal British subjects.

Bone histomorphometric parameters have been measured in a group of normal British subjects of both sexes over a wide age range. There is loss of trabecular mineralized bone volume with advancing age and an increase in osteoid volume and in the trabecular bone surface covered by osteoid seams. There was no change in the mineral appositional rate or in bone resorption surfaces.

Adolescent↗
PubMed1982

Changes in plasma half-life and clearance of 3H-25-hydroxyvitamin D3 in patients with intestinal malabsorption.

The plasma disappearance of intravenously administered tracer doses of tritium-labelled 25-hydroxyvitamin D3 (25OHD3) wa studied in six normal subjects and in 15 patients with intestinal malabsorption. The plasma half-life was significantly shorter and the clearance rate significantly greater in the group with malabsorption compared with the controls. One explanation for this increased elimination could be interruption of an enterohepatic circulation of 25OHD occurring in subjects with malabsorption and such a mechanism could account for the loss of endogenous vitamin D in these patients.

Adult↗
PubMed1982

Faecal tritium excretion after intravenous administration of 3H-25-hydroxyvitamin D3 in control subjects and in patients with malabsorption.

Faecal tritium excretion after intravenous 3H-25-hydroxyvitamin D3 administration was measured in three control subjects and in six patients with small intestine resection or bypass. The mean daily faecal tritium excretion over four to six days ranged from 0.8-1.6% of the injected dose in the controls (mean 1.2) and 0.9-6.8% in the patients (mean 3.7). There was a significant positive correlation between stool volume and the mean daily faecal tritium excretion. No correlation was found between the faecal tritium excretion and the plasma 25-hydroxyvitamin D concentration. Between 2.5 and 19.0% of faecal radioactivity eluted as 3H-25-hydroxyvitamin D3 on silicic acid chromatography. We conclude that faecal loss of endogenous 25-hydroxyvitamin D may be increased after small intestinal resection or bypass. Although the amount lost by this route is relatively small, it may contribute to the development of vitamin D deficiency in patients with malabsorption when endogenous vitamin D3 synthesis is also reduced.

Adult↗
PubMed1982

Value of plasma calcium, phosphate, and alkaline phosphatase measurements in the diagnosis of histological osteomalacia.

Plasma calcium and phosphate concentrations and alkaline phosphatase activities were examined retrospectively in 50 patients with histologically proven osteomalacia and 50 age- and sex-matched control subjects with normal bone histology. An abnormal plasma alkaline phosphatase activity was more useful than an abnormal plasma calcium or phosphate concentration in distinguishing between normal and osteomalacic subjects, producing a false-negative rate of 14% and a false-positive rate of 8%. False-negative and false-positive rates of 10% and 8% respectively were obtained when the presence of an abnormality in any one of the three biochemical measurements was used as a predictor of histological osteomalacia. When discriminant analysis was applied to plasma calcium, phosphate and alkaline phosphatase together a false-negative rate of 12% and a false-positive rate of 0% was obtained.Sixty-two patients in whom a diagnosis of osteomalacia was suspected were investigated prospectively, using both single biochemical abnormalities and the classification functions derived from the discriminant analysis of all three biochemical measurements to predict the presence or absence of histological osteomalacia. Plasma alkaline phosphatase activity gave false-negative and false-positive rates of 10% and 32% respectively but was a more reliable predictor of abnormal bone histology than were plasma calcium or plasma phosphate concentrations or the presence of an abnormality in any one of the three measurements. Discriminant analysis using plasma calcium, phosphate and alkaline phosphatase together produced a false-negative rate of 16% and a false-positive rate of 10%. We conclude that plasma alkaline phosphatase activity is the best single routine biochemical screening test for osteomalacia, although a high false-positive rate may occur. Direct discriminant analysis of plasma calcium, phosphate and alkaline phosphatase together provides a more sensitive method of detecting histological osteomalacia which should be useful in determining the prevalence of osteomalacia within high-risk populations.

Adolescent↗
PubMed1981

Privational and malabsorption metabolic bone disease: plasma vitamin D metabolite concentrations and their relationship to quantitative bone histology.

Plasma 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and 25-hydroxyvitamin D (25OHD) concentrations were measured in twenty patients with metabolic bone disease due either to privational causes (10 patients) or malabsorption (10 patients). Abnormally low plasma 1,25(OH)2D3 levels were found in eleven patients, six with privational and five with malabsorption bone disease. Normal plasma 1,25(OH)2D3 concentrations were found in the remaining nine patients; of these, five were either receiving anticonvulsant therapy or had been hospitalised prior to investigation. In the absence of either of these factors, normal plasma 1,25(OH)2D3 levels were only found in patients with malabsorption-associated bone disease. Plasma 25OHD levels were below normal in eleven patients; six had malabsorption and five had privational bone disease. In the fifteen patients not receiving anticonvulsants there were significant inverse correlations between plasma 1,25(OH)2D3 levels and the osteoid volume, surface and seam thickness index. This study indicates that plasma 1,25(OH)2D3 concentrations are low in privational osteomalacia in the absence of anticonvulsant therapy or hospitalisation, although normal levels may occur in malabsorption metabolic bone disease uncomplicated by these factors. The plasma 1,25(OH)2D3 concentration appears to be inversely related to the histological severity of bone disease in patients not receiving anticonvulsant therapy.

Adult↗
PubMed1981

Comparison of the appearance of radiolabelled vitamin D3 and 25-hydroxy-vitamin D3 in the chylomicron fraction of plasma after oral administration in man.

1. The uptake of either orally administered [3H]vitamin D3 or 25-[3H]hydroxy-vitamin D3 into the chylomicron fraction of plasma was studied in 12 healthy male subjects. 2. The amount of [3H]vitamin D3 in the chylomicron fraction expressed as a percentage of the total plasma radioactivity was higher than that of 25-[3H]hydroxy-vitamin D3. 3. It is suggested that the mechanism of intestinal absorption of vitamin D and 25-hydroxy-vitamin D may differ in man, the absorption of 25-hydroxy-vitamin D possibly being less dependent on bile acids.

Administration, Oral↗
PubMed1981

Vitamin D status and bone histomorphometry in gross obesity.

Plasma 25-hydroxyvitamin D concentrations and bone histomorphometry were investigated in 24 grossly obese subjects. The mean plasma 25OHD concentration was significantly lower in the obese group than in age-matched, healthy controls. Subnormal values were found in four obese subjects and in a further two subjects, who were investigated at the end of the summer, plasma 25-hydroxyvitamin D levels were at the lower end of the normal winter range. Bone histology was abnormal in two patients. In one, mild osteomalacia and secondary hyperparathyroidism were present while in the other patient the appearance suggested increased bone turnover, possibly as a result of healing osteomalacia. We conclude that gross obesity is associated with an increased risk of vitamin D deficiency, probably because of reduced exposure to uv radiation. Histological evidence of metabolic bone disease may also occur. Preoperative vitamin D deficiency may contribute in some patients to the development of metabolic bone disease after intestinal bypass.

Adult↗
PubMed1981

Musculo-skeletal abnormalities after jejunoileal bypass.

A mixture of osteomalacia and hyperparathyroidism is common after jejunoileal bypass (54 per cent). Bone biopsy is essential for diagnosis. Oral l alpha hydroxyvitamin D3 can rapidly reverse the abnormality. Some patients, however, fail to respond and this may be related to bacterial contamination of the excluded loop. Polyarthralgia is also a common side effect (13 per cent). It occurs in bouts lasting a few days and normally subsides spontaneously. It is often associated with skin lesions of vasculitic type. The attacks can be cut short by metronidazole. In some patients relapses are so frequent and severe that reversal of the bypass is indicated since it brings immediate and lasting relief. The possible immune mechanisms involved are complex.

Adult↗
PubMed1980

Vitamin D prophylaxis and osteomalacia in chronic cholestatic liver disease.

Bone histology was examined in 32 patients with chronic cholestatic liver disease, of whom just over one half were receiving high-dose parenteral vitamin D therapy. Four patients had histological evidence of osteomalacia; two of these were receiving vitamin D therapy, and showed only very mild osteomalacia, while the remaining two untreated patients had more severe bone disease. Plasma 25-hydroxyvitamin D levels were normal in all vitamin D-treated patients, and serum calcium concentrations were significantly higher in the treated group. Clinical symptoms and biochemical and radiological findings were unreliable in predicting osteomalacia. It is concluded that osteomalacia is uncommon in patients with chronic cholestatic liver disease irrespective of whether or not they are receiving vitamin D therapy. However, high-dose parenteral vitamin D prophylaxis protects against vitamin D deficiency and may also prevent the development of severe bone disease.

Adult↗
PubMed1980

Treatment of bone disease after jejunoileal bypass for obesity with oral 1 alpha-hydroxyvitamin D3.

The effects of oral 1 alpha-hydroxyvitamin D3 have been investigated in 12 patients with bone disease after jejunoileal bypass for obesity. Bone histology became normal or improved greatly after four to 12 months' treatment in eight patients but showed little change or worsened in four. There was a significant rise in plasma calcium and fall in plasma alkaline phosphatase concentration with 1 alpha-hydroxyvitamin D3 therapy in the patients with a good histological response. Administration of metronidazole and cotrimoxazole to two patients who had failed to respond to 1 alpha-hydroxyvitamin D3 resulted in clinical and biochemical improvement; in one of these patients histological improvement was also documented. It is concluded that oral 1 alpha-hydroxyvitamin D3 can be effective in healing post-bypass bone disease; the failure of some patients to respond may be related to bacterial contamination of the small intestine and in those patients antibiotics may also be indicated.

Adult↗