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Biomedical subjects

D H Marshall

Publications and source records attributed to D H Marshall.

At least 55 records · Page 3Linked to original sources

Treatment of spinal osteoporosis in postmenopausal women.

Ninety-five postmenopausal women with unequivocably wedged or compressed vertebrae in whom the recognised causes of secondary osteoporosis had been excluded were studied, 41 having no treatment and the rest one or more of six different treatments. The treatment regimens comprised calcium supplements, vitamin D, calcium and vitamin D, ethinyloestradiol or--where oestrogens were contraindicated--norethisterone, 1 alpha-hydroxycholecalciferol (1 alpha-OHD3), or hormones with 1 alpha-OHD3. The seven groups were reasonably comparable in most respects except that the hormone-treated patients were younger and had a higher initial cortical area ratio than the others, and the calcium- and hormone-treated groups had the best initial radio-calcium absorption. The untreated osteoporotic patients lost cortical bone more rapidly than do normal postmenopausal women. Three treatments (calcium, hormones, and 1 alpha OHD3 plus hormones) appear to be useful in modifying the disease, and two treatments (vitamin D and 1 alpha-OHD3) useless or even harmful. Vitamin D and 1 alpha-OHD3 are more safely used in conjunction with oestrogens, which protect bone against resorption, than on their own.

Aged↗

A placebo-controlled trial of ethinyl oestradiol and norethisterone in climacteric women.

A placebo-controlled trial has shown that 15 microgram of ethinyl oestradiol is as effective as 25 microgram daily in reducing both menopausal symptoms and the urinary excretion of calcium and hydroxyproline. Norethisterone 5 mg daily also showed a significant reduction in the climacteric symptoms but was less effective than either of the ethinyl oestradiol doses.

Calcium↗

The relation between bone loss and calcium balance in women.

1. We have examined the relation between the rate of cortical bone loss and other measured variables in 108 women, untreated and on various therapies, observed for nearly 300 patient years. The majority of the subjects were postmenopausal women with various degrees of simple osteoporosis, but a few cases of hyperparathyroidism and other calcium disorders were included. 2. Calcium balance, bone resorption rats, urinary hydroxyproline and plasma alkaline phosphatase were shown to be related to the rate of bone loss; patients with the more negative balance or the higher values of the other variables had significantly higher rates of loss. The rate of bone loss was independent of the rate of bone formation.

Aged↗

Factors influencing the intestinal absorption of calcium and phosphorus following renal transplantation.

After successful renal transplantation there is continuing malabsorption of calcium and phosphorus. This is due in part to impaired glomerular filtration rate, and in part to the action of steroid on calcium and phosphorus absorption. The effect of steroids is most marked over the first 18 months after transplantation and causes significant malabsorption of calcium and phosphorus even though good graft function is established. Calcium and phosphorus malabsorption can be improved by exogenous 1,25-dihydroxy vitamin D (oral 1 alpha-OH D3 or 1,25-[OH]2D3).

Adolescent↗

Vitamin D and magnesium absorption in man.

1. The effects of vitamin D and its hydroxylated derivatives on calcium and magnesium absorption have been examined in 47 balance studies on patients with various disorders of calcium or bone metabolism. 2. Vitamin D significantly increased the mean net absorption of calcium and also the calcium balance. The mean net absorption of magnesium was also significantly increased although the rise was much less than that of calcium and the mean magnesium balance was unaffected. 3. It is suggested that the slight effect of vitamin D on magnesium absorption may be incidental to its stimulation of active calcium transport, since the latter system has weak affinities for other alkaline earth ions including strontium, barium and magnesium.

Absorption↗

Prevalence, pathogenesis and treatment of post-menopausal osteoporosis.

About 11% of post-menopausal women with wrist fractures have spinal osteoporosis with compressed vertebrae, and about 25% of postmenopausal osteoporosis patients have had a wrist fracture. The estimated prevalence of post-menopausal spinal osteoporosis is 4% of the female population at age 60 and about 8% at age 80. Osteoporotic patients have lower plasma oestrone and androstenedione levels, lower calcium absorption and higher urinary hydroxyproline than matched controls. Of six treatments tested in three different ways, the least successful were vitamin D2 and 1 alpha-OHD3 and the most successful were hormones with or without 1 alpha-(OH)2D3 and calcium supplements. Calcium and vitamin D given in combination occupied an intermediate position.

Aged↗

Calcium requirement and calcium therapy.

The mean calcium requirement of normal adults has been estimated from 212 calcium balances on 84 normal subjects and found to be 578 mg. The calcium allowance required to ensure that 95% of normal adults are in calcium balance is about 900 mg. Calcium requirement is relatively higher than that of phosphorus or magnesium because plasma calcium--and therefore urine calcium--is maintained at the expense of the skeleton in the presence of calcium deficiency, whereas plasma phosphate and magnesium--and therefore urine phosphate and magnesium--fall on phosphorus and magnesium deficient diets. Calcium requirement appears to rise at the menopause, and postmenopausal bone loss can be reduced by calcium supplements. In postmenopausal osteoporosis, the severe negative calcium balance can be corrected by giving calcium or calcium and vitamin D, but vitamin D alone is not beneficial. Similarly, bone loss, height loss and further vertebral compression can be reduced by calcium or calcium and vitamin D but not by vitamin D alone.

Bone Diseases↗

Thermal transformation of cholecalciferol between 100--170 degrees C.

Cholecalciferol is transformed, irreversibly, to pyrocholecalciferol and isopyrocholecalciferol. The rate constant, as a function of temperature, for this transformation from the equilibrium mixture of cholecalciferol and precholecalciferol has been determined for temperatures between 100--170 degrees C and is slower than the precholecalciferol-cholecalciferol interconversion. The ratio of rates of production of pyro to isopyro derivatives is 2:1 throughout.

Chemical Phenomena↗

The relation between plasma androstenedione, plasma oestrone and androstenedione to oestrone conversion rates in post-menopausal women with and without fractures.

1. Plasma androstenedione, plasma oestrone and the conversion of plasma androstenedione into oestrone were measured in 19 post-menopausal women without fractures (six of them oophorectomized) and 18 with vertebral or femoral neck fractures (four of them oophorectomized). 2. In the series as a whole, the main determinant of the plasma oestrone level was the plasma androstenedione concentration. Only in the small oophorectomized group did the variation in conversion rate make a significant contribution to the variation in plasma oestrone. 3. The conversion rates were not different as between non-fracture and fracture cases but the mean plasma androstenedione and oestrone concentrations were lower (though not significantly) in the latter.

Adrenal Glands↗

The relation between plasma androstenedione and oestrone levels in untreated and corticosteroid-treated post-menopausal women.

Plasma oestrone (E1) and androstenedione (A) were measured in 96 untreated and 18 corticosteroid-treated post-menopausal women. Levels of both hormones were consistently lower in the steroid-treated cases, presumably due to suppression of ACTH secretion. There was a clear relationship between A and E1 levels in both groups and when the data were pooled they formed a continuous series with a curvilinear relationship going through the origin. This relationship could be described by an equation based on Michaelis-Menten kinetics, suggesting that the rate of A to E1 conversion is an inverse function of the plasma androstenedione level. The main determinant of plasma E1 was plasma A; body weight and age were of subsidiary importance. Secondary oestrogen deficiency may be a factor in the genesis of steroid-induced osteoporosis in post-menopausal women and oestrogen therapy may be indicated in this group of patients.

Adrenal Cortex Hormones↗

Risk factors in calcium stone disease of the urinary tract.

The concept that calcium stone formation may be explained on the basis of a number of risk factors is developed. The main risk factors involved are shown to be calcium, oxalate, pH, acid mucopolysaccharides and uric acid. A method is described for calculating and combining the individual risk factors into a measure of the "relative probability" of forming stones (PSF). PSF values are generally lower in normal subjects than in stone-formers. Amongst the normals, PSF values are lower in children and women than in men. Recurrent stone-formers have the highest PSF values and these correlate well with the severity of the diseases as defined by the stone episode rate of the patient. Single stone-formers have PSF values intermediate between those of normal men and those of recurrent stone-formers.

Adult↗

Reversal of betamethasone-induced inhibition of intestinal calcium absorption by 1alpha-hydroxycholecalciferol.

The intestinal absorption of calcium has been studied in conscious, unstressed pigs, using a modification of the double isotope technique. The oral administration of betamethasone (1 mg/day) to four pigs (25--33 kg) for 4 weeks reduced the calcium absorption coefficient, calculated after the intravenous and oral administration of 47Ca2+, by a mean value of 66%. The oral administration of 1alpha-hydroxycholecalciferol (2 microgram/day) in combination with beta-methasone (1 mg/day) for a further 4 weeks returned the absorption coefficient to the control value.

Animals↗

Plasma androstenedione and oestrone levels in normal and osteoporotic postmenopausal women.

Plasma androstenedione and oestrone concentrations were measured in 72 postmenopasual women. The women included some who had undergone oophorectomy, some with osteoporosis, and normal controls; they were matched for years since menopause. Both hormone concentrations were significantly reduced in the women with osteoporosis. The women who had undergone oophorectomy had hormone concentrations intermediate between the normal and osteoporotic values. Oestrogen deficiency secondary to low androstenedione levels is a major risk factor in postmenopausal osteoporosis, and may be caused by failure of ovarian stromal androgen secretion or some abnormality in the pituitary-adrenal axis.

Adult↗