scholarly journals Calcium metabolism in lactating ewes

1969 ◽  
Vol 23 (4) ◽  
pp. 827-834 ◽  
Author(s):  
G. D. Braithwaite ◽  
R. F. Glascock ◽  
Sh. Riazuddin
Keyword(s):  
Bone Resorption ◽  
Calcium Metabolism ◽  
Early Lactation ◽  
Isotope Techniques ◽  
Positive Balance ◽  
Low Rate

1. A combination of balance and isotope techniques has been used to study calcium metabolism at different stages of lactation in six sheep and the results have been compared with those obtained from four of the sheep 1 month after the end of lactation.2. At first the animals were in negative Ca balance but, as milk yields decreased, so the animals moved progressively into positive balance.3. Ca absorption from the gut was significantly increased throughout the whole of lactation but not sufficiently to meet the initial high demands for Ca.4. Most of the extra Ca was supplied by bone resorption which was high in early lactation and decreased to a very low value at the end.5. The rate of bone accretion remained constant throughout the period and was 1.5 times as high as in the non-lactating animals.6. In the later stages, a combination of factors, but in particular a low rate of resorption of bone, enabled the animals to replenish some of the Ca lost from the skeleton in early lactation.7. A month after the end of lactation replenishment of skeletal stores of Ca was still continuing as shown by the excess of bone accretion over bone resorption.

scholarly journals Calcium metabolism in pregnant ewes

1970 ◽  
Vol 24 (3) ◽  
pp. 661-670 ◽  
Author(s):  
G. D. Braithwaite ◽  
R. F. Glascock ◽  
Sh. Riazuddin
Keyword(s):  
Bone Resorption ◽  
Reproductive Cycle ◽  
Calcium Metabolism ◽  
Marked Change ◽  
Late Pregnancy ◽  
Early Lactation ◽  
Isotope Techniques ◽  
Milk Fever ◽  
Rate Of Absorption

1. A combination of balance and isotope techniques has been used to study calcium metabolism in ten sheep at different stages of pregnancy, and the results have been combined with earlier results obtained during lactation to show the variations in Ca metabolism which occur during the whole reproductive cycle.2. Transfer of Ca to the foetuses during pregnancy and to the milk after parturition rose rapidly from the 65th day of gestation and reached a maximum at parturition or shortly afterwards.3. Although the rate of absorption of Ca from the intestine increased steadily throughout pregnancy it was insufficient to meet the full requirements of late pregnancy and early lactation. During this period, the extra Ca was supplied by increased bone resorption.4. The maternal Ca balance became negative during pregnancy, the net daily loss of Ca reaching a maximum in early lactation.5. In late lactation the maternal Ca balance became positive enabling the animals to replenish their skeletal stores.6. There was no marked change in the demands for Ca at parturition and the connexion between this observation and the pathogenesis of milk fever is discussed.7. Rates of transfer of Ca to the foetus during pregnancy are compared with estimated values of other workers.

Circulating vitamin D metabolites and hypercalcaemia of malignancy

1984 ◽  
Vol 106 (4) ◽  
pp. 556-563 ◽  
Author(s):  
Stuart H. Ralston ◽  
Robert A. Cowan ◽  
Andrew G. Robertson ◽  
Mary D. Gardner ◽  
Iain T. Boyle
Keyword(s):  
Vitamin D ◽  
Bone Resorption ◽  
Primary Hyperparathyroidism ◽  
Cancer Patients ◽  
Calcium Metabolism ◽  
Reliable Method ◽  
Plasma Concentrations ◽  
Significant Proportion ◽  
Vitamin D Metabolites ◽  
Active Vitamin

Abstract. Plasma concentrations of 1.25 dihvdroxvcholecalciferol were measured in 44 patients with malignancy associated hvpercalcaemia and related to other hormonal regulators of calcium metabolism. Immunoreactive PTH concentrations were suppressed in all but 2 patients and, as a group, patients with hvpercalcaemia of malignancy had lower 1,25 dihydroxycholecalciferol concentrations than normocalcaemic cancer patients. 1,25 dihydroxycholecalciferol concentrations were clearly detectable in a significant proportion (43%) of hypercalcaemia cases however, suggesting that in these patients the active vitamin D metabolite may contribute to the pathogenesis and maintenance of the hypercalcaemia by stimulating bone resorption, and/or by increasing absorption of calcium from the intestine. Measurement of plasma 1,25 dihydroxycholecalciferol concentration does not provide a wholly reliable method for distinguishing the hypercalcaemia of malignancy from primary hyperparathyroidism.

Decreased bone mass and increased bone turnover with valproate therapy in adults with epilepsy [RETRACTED]

Neurology ◽  
2001 ◽  
Vol 57 (3) ◽  
pp. 445-449 ◽  
Author(s):  
Y. Sato ◽  
I. Kondo ◽  
S. Ishida ◽  
H. Motooka ◽  
K. Takayama ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Mass ◽  
Calcium Metabolism ◽  
Type I Collagen ◽  
Bone Resorption Marker ◽  
Type I ◽  
Serum Concentrations ◽  
Mineral Density ◽  
Z Scores

Background: Bone loss and hypovitaminosis D are reported in patients taking antiepileptic drugs, but little is known about changes in bone and calcium metabolism from valproic acid (VPA).Objective: To assess the relationship of VPA to bone mass and calcium metabolism in 40 adults with epilepsy on long-term VPA monotherapy, 40 age- and sex-matched epileptic patients taking phenytoin (PHT), and 40 healthy control subjects. Bone mineral density (BMD) of the second metacarpal was determined as T- and Z-scores.Results: BMD reduction from control values was 14% (12% in men, 16% in women) with VPA and 13% (12% in men, 15% in women) with PHT. Among patients on VPA, nine (23%) had T-scores below −2.5 SD, suggesting osteoporosis; 15 (37%) had T-scores between −1 and −2.5 SD, suggesting osteopenia. Serum concentrations of calcium were significantly higher with VPA than in PHT or control groups. Serum concentrations of bone Gla protein (a bone formation marker) and pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP; a bone resorption marker) associated with either drug significantly exceeded control values. Z-scores for BMD in the VPA group correlated negatively with calcium and ICTP. High ICTP correlated positively with ionized calcium, implying that increased bone resorption caused the latter.Conclusion: Long-term VPA monotherapy can increase bone resorption, leading to decreased BMD.

Evolution of a Surge-Type Glacier in its Quiescent Phase: Kongsvegen, Spitsbergen, 1964–95

1998 ◽  
Vol 44 (147) ◽  
pp. 394-404 ◽  
Author(s):  
Kjetil Melvold ◽  
Jon Ove Hagen
Keyword(s):  
Mass Transfer ◽  
Steady State ◽  
Accumulation Rate ◽  
Rate Of Change ◽  
Cold Climate ◽  
Surface Geometry ◽  
Phase Measurements ◽  
Quiescent Phase ◽  
Positive Balance ◽  
Low Rate

AbstractKongsvegen is a 102 km2sub-polar (polythermal) surge-type glacier in northwest Spitsbergen, Svalbard. It surged just before 1948 and is currently in its quiescent phase. Measurements of surface geometry since 1966 show a retreat of the front and strong thinning of up to 75 m in the ablation area, and a build-up of up to 32 m in the accumulation area. Present-day annual velocities along the glacier are low, from 1.4 up to 3.6 m a-1. The measured mean net balance for the period 1987-94 and the balance reconstructed back to 1967 show a weak positive balance of about 0.1 m w.e. The measured actual ice flux is low and the mass transfer down-glacier at the ELA is only about 3-20% of that required for steady state. Thus, the glacier is building up towards a new surge. The total thickening rate on Kongsvegen is somewhat higher than in other cases from Svalbard, but it is small compared with other well-studied surge-type glaciers in Alaska and the Pamirs. This relatively low rate of change is a function of the low accumulation rate and the relatively cold climate compared to other areas and is common for surge-type glaciers in Svalbard.

Effects of a diphophonate on calcium metabolism in calcium-deprived rats

1975 ◽  
Vol 228 (6) ◽  
pp. 1750-1756 ◽  
Author(s):  
DB Morgan ◽  
A Gasser ◽  
U Largiader ◽  
A Jung ◽  
H Fleisch
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Bone Formation ◽  
Kinetic Parameters ◽  
Calcium Intake ◽  
Calcium Metabolism ◽  
Published Data ◽  
Efficient Mechanism ◽  
Growing Rats ◽  
Inhibit Bone Resorption

Calcium metabolism was studied in growing rats, submitted to calcium deprivation ofvarious intensity. A decreased intake resulted in decreased net absorption of calcium(V'na), no change in bone formation (V'o+), and an increase in bone resorption (V'o -). In animals given dichloromethylene disphosphate (Cl'2MDP), a compoundknown to inhibit bone resorption, V'o+ was less than in the controls but again the same at all calcium intakes; V'na was below V'o+, V'o- still increased as the calcium intake was reduced. The various kinetic parameters in rats receiving Cl'2MDPwere indistinguishable from published data in parathyroidectomized (PTX) animals, yetblood calcium was low in PTX rats but normal in Cl'2MDP-atreated rats. It appears that the rat has an efficient mechanism for increasing bone resorption which is not inhibited by Cl'2MDP and does not require parathyroid hormone.

scholarly journals Calcium Metabolism in Bone Disease: Effects of Treatment with Microcrystalline Calcium Hydroxy Apatite Compound and Dihydrotachysterol1

1980 ◽  
Vol 73 (11) ◽  
pp. 780-785 ◽  
Author(s):  
C E Dent ◽  
I J T Davies
Keyword(s):  
Adverse Effects ◽  
Calcium Metabolism ◽  
Calcium Hydroxyapatite ◽  
Calcium Balance ◽  
Hydroxy Apatite ◽  
Bone Demineralization ◽  
Calcium Retention ◽  
Number Of Patients ◽  
Positive Balance ◽  
Small Doses

Microcrystalline calcium hydroxyapatite compound (MCHC) was given orally together with small doses of dihydrotachysterol (DHT) to a number of patients with osteogenesis imperfecta (OI). Serial calcium and phosphate balances in three patients representing wide variations in severity of OI are presented over periods from eight months to two years. The combination of MCHC and DHT resulted in an immediate positive calcium balance which was maintained throughout the period of assessment in 2 cases. However, no radiological improvement could be demonstrated. Substituting calcium gluconate for MCHC resulted in a reduction of positive balance. No adverse effects were noted. The reasons why MCHC with DHT should result in increased calcium retention are discussed. This combination of MCHC and DHT could be of benefit in many common situations of bone demineralization, such as osteoporosis.

scholarly journals The effect of growth hormone on calcium metabolism in the sheep

1975 ◽  
Vol 33 (3) ◽  
pp. 309-314 ◽  
Author(s):  
G. D. Braithwaite
Keyword(s):  
Growth Hormone ◽  
Bone Resorption ◽  
Calcium Metabolism ◽  
Nutrient Balance ◽  
Subcutaneous Administration ◽  
Bovine Growth Hormone ◽  
Hormone Production ◽  
Exchangeable Ca ◽  
Balance Technique

1. The effect of subcutaneous administration of bovine growth hormone on calcium metabolism of nearly mature wether sheep has been studied by a combination of a radioactive technique and a nutrient balance technique.2. Administration of growth hormone resulted in a significant increase in the rates of absorption of Ca, accretion of Ca into bone, resorption of Ca from bone and skeletal retention of Ca, and also in the sizes of the exchangeable Ca pools.3. Retention of phosphorus was also significantly increased.4. These changes suggest that the effect of growth hormone was to alter the Ca metabolism of nearly mature wethers to resemble that of younger, more actively growing animals.5. Results are consistent with the theory that oestrogens may alter Ca metabolism of wethers by increasing growth hormone production.

Effect of 1α,24(R)-dihydroxyvitamin D3 on calcium metabolism in the rat

1986 ◽  
Vol 111 (4) ◽  
pp. 572-576 ◽  
Author(s):  
S. Yamada ◽  
J.-P. Bonjour ◽  
H. Fleisch
Keyword(s):  
Vitamin D ◽  
Bone Resorption ◽  
Bone Formation ◽  
Urinary Excretion ◽  
Intestinal Absorption ◽  
Calcium Metabolism ◽  
Significant Rise ◽  
Whole Body ◽  
Dihydroxyvitamin D3 ◽  
Vitamin D Analogue

Abstract. It has been suggested that 1α,24(R)-dihy droxyvitamin D3 (1,24(OH)2D3), a chemically synthesized vitamin D analogue, may have the property to enhance whole-body Ca retention and may thus be of use in osteoporosis. In order to test this hypothesis the main fluxes of Ca metabolism were measured in vitamin D-replete rats injected ip with 1,24(OH)2D3 at daily doses of 25, 50 and 100 pmol for 10 days. As compared with pair fed control animals, rats treated with 1,24(OH)2D3 displayed a significant rise in net intestinal absorption of Ca and in urinary excretion of Ca, and increase in bone resorption but no significant change in bone formation. Whole body Ca retention was not changed at 25 pmol/day and showed a trend to decrease at 50 and 100 pmol/day. In conclusion these results do not suggest that among available vitamin D analogues, 1,24(OH)2D3 would be particularly useful for increasing bone Ca retention in osteoporosis.

scholarly journals Evolution of a Surge-Type Glacier in its Quiescent Phase: Kongsvegen, Spitsbergen, 1964–95

1998 ◽  
Vol 44 (147) ◽  
pp. 394-404 ◽  
Author(s):  
Kjetil Melvold ◽  
Jon Ove Hagen
Keyword(s):  
Mass Transfer ◽  
Steady State ◽  
Accumulation Rate ◽  
Rate Of Change ◽  
Cold Climate ◽  
Surface Geometry ◽  
Phase Measurements ◽  
Quiescent Phase ◽  
Positive Balance ◽  
Low Rate

AbstractKongsvegen is a 102 km2 sub-polar (polythermal) surge-type glacier in northwest Spitsbergen, Svalbard. It surged just before 1948 and is currently in its quiescent phase. Measurements of surface geometry since 1966 show a retreat of the front and strong thinning of up to 75 m in the ablation area, and a build-up of up to 32 m in the accumulation area. Present-day annual velocities along the glacier are low, from 1.4 up to 3.6 m a-1. The measured mean net balance for the period 1987-94 and the balance reconstructed back to 1967 show a weak positive balance of about 0.1 m w.e. The measured actual ice flux is low and the mass transfer down-glacier at the ELA is only about 3-20% of that required for steady state. Thus, the glacier is building up towards a new surge. The total thickening rate on Kongsvegen is somewhat higher than in other cases from Svalbard, but it is small compared with other well-studied surge-type glaciers in Alaska and the Pamirs. This relatively low rate of change is a function of the low accumulation rate and the relatively cold climate compared to other areas and is common for surge-type glaciers in Svalbard.

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