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Biomedical subjects

M Peacock

Publications and source records attributed to M Peacock.

At least 127 records · Page 7Linked to original sources
PubMed1984

Staining of the calcification front in human bone using contrasting fluorochromes in vitro.

Histological studies on bone from the human iliac crest have suggested that if the customary techniques of labeling in vivo with certain fluorochromes such as tetracycline are replaced or augmented by simple whole tissue staining in vitro using the same reagents, differences in the pattern of extracellular fluorescence between normal and pathological states are retained. In particular, the association of the fluorescence with the calcification front in stained examples is closely comparable to similar examples that have been labeled (r = 0.988, p less than 0.001) and to other tinctorial methods (r = 0.891, p less than 0.001). While the stain alone lacks the time lapse of multiple labels, when administered some days after a single label at the time of biopsy, it provides an effective second marker and a measure of mineralization rate that does not differ significantly from that using double labels. Moreover, since the problems of toxicity are avoided by staining, a range of contrasting fluorochromes previously restricted to animal studies may now be used in man. In particular, the enhanced color differentiation brought about by the combination of tetracycline label followed by xylenol orange stain improves image resolution and greatly aids interpretation.

Bone Diseases↗
PubMed1983

Vitamin D metabolites in post-menopausal women and their relationship to the myopathic electromyogram.

Proximal muscular weakness is a feature of many metabolic bone diseases but is not well recognized in spinal osteoporosis. Thirty-six post-menopausal women presenting with back pain, with or without osteoporosis, were therefore studied in order to define the relationship between abnormal electromyographic findings and disturbed vitamin D metabolism, as both low plasma 1,25 dihydroxy vitamin D concentrations and malabsorption of calcium have been reported in osteoporosis. Patients with abnormal electromyograms had lower concentrations of plasma 1,25 dihydroxy vitamin D (mean 78.3 pmol/l, SD 20.5, n = 15) than normal subjects of similar age (mean 110.4 pmol/l, SD 39.4, n = 21; P less than 0.01), but electromyographic abnormality was not associated with changes in radiocalcium absorption, plasma 25 hydroxy vitamin D, plasma calcium or phosphate or urinary calcium or hydroxy-proline excretion or impaired renal function. There was no relationship between abnormal electromyography and osteoporosis assessed by spinal radiographs and iliac crest biopsy. These findings are consistent with our previous suggestion that muscle weakness in many unrelated bone disorders is related to low plasma 1,25 dihydroxy vitamin D concentrations, but suggest that there is no relationship between proximal myopathy and spinal osteoporosis in post-menopausal women.

25-Hydroxyvitamin D 2↗
PubMed1983

Calcium malabsorption in the elderly: the effect of treatment with oral 25-hydroxyvitamin D3.

Calcium malabsorption is common in the elderly and may contribute to the development of age-related bone loss. To investigate its cause, we have measured radio-calcium absorption, plasma 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and parathyroid hormone in forty-eight elderly women with a normal plasma creatinine. Calcium malabsorption was associated with low 25-hydroxyvitamin D concentrations and was corrected by increasing these into the normal range by treatment with oral 25-hydroxyvitamin D3. Treatment also increased 1,25-dihydroxyvitamin D, and decreased parathyroid hormone concentrations. Before treatment, plasma parathyroid hormone was related to plasma creatinine but not to 25-hydroxyvitamin D, and the change in absorption on treatment correlated inversely with plasma creatinine. 51Cr EDTA clearance was measured in sixteen elderly women and confirmed that renal impairment was common even with a plasma creatinine in the normal range. Our results suggest that calcium malabsorption in the elderly is predominantly due to vitamin D deficiency; renal impairment is also common and contributes to the malabsorption by increasing the requirements for vitamin D.

Absorption↗
PubMed1983

Studies on the prevalence and epidemiology of urinary stone disease in men in Leeds.

A postal survey among 2% of men in Leeds showed that the prevalence of urinary stone disease is 3.8%. The prevalence of upper urinary tract and spontaneously passed stones increases progressively from 0.7% in social class 5 to 5.0% in social class 1 but that of bladder stones (0.7% in the group as a whole) is independent of social class. There is an initial peak of upper urinary tract and spontaneously passed stones commencing at age 20 and having a projected prevalence at age 90 of 5.7% and a second peak of bladder stones, commencing about age 50, with a projected prevalence of 1.9%. The prevalence of stone disease increases according to the order: single less than divorced/separated less than married less than widowed men. A family history of stones tends to be higher amongst relatives of stone-formers than amongst the corresponding relatives of control subjects, the male/female ratio being 2:1. The occurrence of urinary stones is significantly associated with that of gallstones, high blood pressure, backache, arthritis and gout but not with that of peptic ulcer, diabetes, thyroid disease or bronchitis.

Adult↗
PubMed1983

Prolonged heparin therapy in pregnancy causes bone demineralization.

The relation of heparin therapy to osteoporosis was assessed in a retrospective analysis of 20 women treated during and after pregnancy with subcutaneous heparin for thromboembolism prophylaxis. The phalangeal cortical area ratio was significantly less after long term therapy (greater than 25 weeks) compared with that after short term therapy (less than 7 weeks). The same trend was found in the metacarpal area ratio, although this did not reach statistical significance. The changes were most marked in a woman who had received heparin also in a previous pregnancy. No correlations were found between duration of therapy and back pain, conventional radiology of lumbar spine or the Singh index of femoral trabecular pattern which were within the normal range in all patients. The findings indicate a dose-related demineralization process associated with prophylactic heparin therapy in pregnancy. The correct methods of and criteria for thromboembolism prophylaxis in pregnancy need critical re-examination.

Adult↗
PubMed1983

Primary hyperparathyroidism associated with primary hyperaldosteronism.

Two patients with both primary hyperparathyroidism and primary hyperaldosteronism are described. Each presented with high blood pressure and a history of renal calculi. Mild hypercalcaemia was associated with raised plasma parathyroid hormone concentrations and a parathyroid adenoma was excised from each. Both patients also had hypokalaemia, hyperaldosteronism and low plasma renin concentrations. Quadric analysis, adrenal vein plasma aldosterone concentrations, adrenal venography and CT scanning all suggested an adrenal adenoma in each patient. This suspicion was confirmed at operation in one patient; the other patient is unfit for adrenal surgery but her blood pressure and plasma potassium concentration have remained within the normal range during prolonged treatment with either spironolactone or amiloride. Because of this unusual association a search was made for parathyroid hormone excess in patients with primary hyperaldosteronism and for aldosterone excess in primary hyperparathyroidism. None was found.

Adult↗
PubMed1982

1-Alpha-hydroxy vitamin D in dialysis bone disease: radiological changes after 6 and 12 months of treatment.

Biochemical, radiological and histological indicators of dialysis bone disease were studied before, 6 months (58 patients) and 12 months (48 patients) after starting treatment with 1 alpha-OH D3. Radiographic healing of subperiosteal erosions was seen after 6 months in 60% and after 12 months in 77% of affected patients. Radiographic improvement, however, was not significantly related to reductions in resorptive surfaces seen on quantitative bone histology, nor to changes in plasma concentrations of immunoreactive parathyroid hormone. Metastatic calcification appeared or increased in 43% of patients after 6 months and 52% after 12 months. Periosteal new bone developed or increased in 14% of patients after 6 months and 17% after 12 months. Both metastatic calcification and periosteal new bone formation were associated with high plasma phosphate concentrations, but not with plasma calcium, alkaline phosphatase or parathyroid hormone concentrations. Treatment with 1 alpha-OH D3 produces radiological improvement in the majority of patients with dialysis bone disease, but the lack of correlation with histological changes confirms the need for regular radiographic examination. Metastatic calcification and periosteal new bone formation probably represent toxicity of 1 alpha-OH D3 but may be minimised by phosphate restriction.

Adolescent↗
PubMed1982

Dialysate aluminium concentration and renal bone disease.

We studied 40 patients maintained on regular hemodialysis, using radiology and quantitative bone histology to assess the relationship between renal bone disease and exposure to aluminium. Fractures were significantly more common in patients exposed to high dialysate aluminium concentrations. The histologic indices of osteomalacia were significantly related to the prevailing dialysate aluminium concentration, in such a way that higher aluminium levels were associated with more osteomalacia. Patients who had been exposed to higher concentrations of aluminium also tended to have a lower plasma phosphate concentration, and associated hypercalemia was seen in 6 patients with osteomalacia. These findings suggest that aluminium is a toxic agent associated with a mineralizing defect in the bone of renal failure patients. This may explain the incomplete response of some patients with renal osteomalacia to administration of 1,25-dihydroxy vitamin D.

Adolescent↗
PubMed1982

Phosphate treatment of recurrent calcium stone disease.

A group of 38 male recurrent idiopathic calcium stone formers were treated with oral supplements of orthophosphate (1 g phosphorus extra in the diet per day) and followed at intervals up to 4 years. The urinary excretion of calcium decreased (p less than 0.001) and that of inorganic phosphate increased (p less than 0.001) during treatment. These changes resulted in a small decrease in the supersaturation of urine with respect to calcium oxalate, sufficient to reduce the percentage of urines which exceeded the upper limit of solubility of that salt, and a small increase in the supersaturation of urine with respect to calcium phosphate. The stone episode rate on treatment fell in 35 of the 38 patients from a mean pretreatment value of 0.66 episodes/year to 0.22 episodes/year. The 3 initially most prolific stone formers increased their rate of stone formation during treatment. Plasma biochemistry showed no evidence of parathyroid stimulation.

Calcium Oxalate↗
PubMed1982

The pattern of urinary stone disease in Leeds and in the United Kingdom in relation to animal protein intake during the period 1960-1980.

Studies on the occurrence of urinary stone disease in Leeds between 1960 and 1980 show that there was an increase in the number of stones formed during the period 1960-1970, a fall between 1972 and a subsequent rise between 1977 and 1980. The fluctuations in stone incidence were accounted for almost entirely by changes in the number of 'pure' calcium oxalate stones and, to a lesser extent, the number of uric acid stones produced. The incidence patterns of these types of stone closely reflected changes in the consumption of animal protein in the population as a whole during the same period. There were no parallel changes either in the number of stones consisting of a mixture of calcium oxalate and calcium phosphate or in the number of infection stones.

Dietary Proteins↗
PubMed1982

Prevalence of urinary stone disease in vegetarians.

A study was carried out to determine the effect of a low animal protein diet, such as taken by vegetarians, on the risk of urinary stone disease. A nation-wide survey of vegetarians in the UK showed that the prevalence of urinary stone formation is 40-60% of that predicted for a group of individuals taken from the general population and matched for age, sex and social class with the vegetarians. The findings support the hypothesis that a diet low in animal protein reduces the risk of urinary stone formation.

Adult↗
PubMed1981

Effect of intestinal surgery on the risk of urinary stone formation.

The prevalence of urinary stone disease in 426 patients who had undergone bowel surgery at the General Infirmary at Leeds from 1958 to 1978 was found by postal questionnaire to be 9.4%. The risk of urinary stone formation was determined from the composition of 24 hour urines from 61 unselected patients, in whom intestinal resections had been performed. There were 27 patients with an ileostomy, 17 patients with an ileostomy and a small bowel resection, and 17 patients with a small bowel resection, or bypass, and an intact colon. Of this group of 61 patients, 9.8% gave a history of urinary stones after surgery. Compared with normal control subjects ileostomy patients had significantly lower urinary pH and volume, higher concentrations of calcium, oxalate, and uric acid, and increased risk of forming uric acid and calcium stones: a small bowel resection combined with an ileostomy increased the ileostomy output, lowered the urinary volume further, and reduced urinary calcium excretion. The concentration of urinary oxalate increased and the risk of both uric acid and calcium stones was high. Patients with small bowel resection and intact colon had hyperoxaluria and an increased risk of calcium stones despite a low urinary calcium. There was no increased risk of uric acid stones in this sub-group. It is concluded that the risk of forming urinary stones after this type of surgery is considerable. The follow-up of patients with ileostomies and with small bowel resections should include an assessment of faecal losses and urinary composition to identify the patients who have a high risk of forming urinary stones.

Adult↗
PubMed1981

Relative importance of renal failure and increased bone resorption in the hypercalcaemia of myelomatosis.

In order to define the relative importance of renal failure and increased bone resorption in the hypercalcaemia of myelomatosis 22 untreated patients were studied, of whom 12 were hypercalcaemic. Most patients had malabsorption of radiocalcium from the gastrointestinal tract and evidence of increased bone resorption as assessed by fasting urinary hydroxyproline/creatinine ratio. The mean OHPr/Cr ratio, however, was similar in patients with and without hypercalcaemia. Renal failure and Bence Jones proteinuria occurred more frequently in the hypercalcaemic patients. In four patients with hypercalcaemia there was an increase in OHPr/Cr after saline infusion accompanied by an improvement in renal function and hypercalcaemia. Mithramycin given to the same patients further reduced hypercalcaemia, presumably by inhibiting bone resorption. It was concluded that the hypercalcaemia of myelomatosis is due to the combination of renal failure and increased bone resorption, but that the OHPr/Cr ratio in the untreated state is a poor indicator of the degree of bone resorption in hypercalcaemic patients.

Acute Kidney Injury↗