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Biomedical subjects

L Cancela

Publications and source records attributed to L Cancela.

25 records · Page 2Linked to original sources
PubMed1986

Relationship between bone GLA-protein (BGP) and calcidiol (25-hydroxycalciferol) in serum of breast-fed infants.

The aim of this investigation was to study the bone metabolism in early infancy by establishing the relationship between serum osteocalcin levels and the hormonal vitamin D status of exclusively breast-fed infants during their first month of life. Calcium, phosphorus, alkaline phosphatase, 25-hydroxycalciferol (calcidiol), 1,25-dihydroxycalciferol (calcitriol) and osteocalcin (BGP or GLA-protein) were measured in 22 healthy lactating women and their paired breast-fed infants before and after supplementation (400 IU vitamin D per day). Prior to supplementation calcidiol, calcitriol and osteocalcin remained unchanged. Following supplementation there was an increase in all the parameters with the exception of calcitriol. The administration of vitamin D to breast-fed infants should in fact have an effect on bone activity as reflected by the increase in osteocalcin levels.

25-Hydroxyvitamin D 2↗
PubMed1985

Effect of 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 maternal loads on maternal and fetal vitamin D metabolite levels in the rat.

Two groups of female rats were used to investigate vitamin D metabolism in the pregnant animals and in their fetuses. In the first group, 3 micrograms of 25-hydroxyvitamin D3 (25-OH-D3) per kg of body weight were injected into intact or nephrectomized (NX) pregnant rats 3 h before sacrifice on day 21 of pregnancy; in the second group, 2 and 6 ng, respectively, of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) per day were infused continuously into pregnant rats between days 17 and 21 of pregnancy. The findings in the fetuses were obtained by quantitative analysis of extracts (Extrelut) of total fetal body lipids; the extracts were purified on Sep Pak and vitamin D sterols were further separated by high-pressure liquid chromatography. Three hours after the dams were injected with 25-OH-D3, the maternal plasma concentration (mean +/- SD) of 1,25(OH)2D3 was 221 +/- 84 pg/ml. In NX pregnant rats, the 1,25(OH)2D3 levels were still elevated: 95.6 +/- 49.0 pg/ml vs 45 +/- 22 pg/ml in control rats. In fetuses from intact or NX dams, the levels of 25-OH-D3 and 1,25(OH)2D3 were not different from the results obtained in the control fetuses but 24,25(OH)2D3 concentrations were increased (6.7 +/- 1.2 ng vs 2.2 +/- 0.7 ng/g body weight). After maternal infusion of 2 or 6 ng/day of 1,25(OH)2D3 (n = 8), plasma concentrations (mean +/- SD) of the metabolite were 64 +/- 31 and 517 +/- 356 pg/ml, respectively, the second being significantly higher than that of the control rats; 25-OH-D3 and 24,25(OH)2D3 levels did not change. 1,25(OH)2D3 contents (mean +/- SD) in fetuses from the treated dams were not different from those of control fetuses (10 +/- 2 pg/g body weight). Our results suggest that pregnant rats and their fetuses were protected against an excessive increase of 1,25(OH)2D3 concentrations in the maternal plasma; although there was some individual hypercalcemia, no significant increase in mean calcemia was detected in the dams, and 1,25(OH)2D3 either did not cross the placental barrier or was rapidly metabolized because we did not find any changes in the fetal content. As in intact or NX pregnant rats, 25-OH-D3 was metabolized into 1,25(OH)2D3, the increase of 24,25(OH)2D3 in the fetuses might be associated with a protective mechanism.

Acid Phosphatase↗
PubMed1985

Vitamin D3 3 beta sulfate has less biological activity than free vitamin D3 during pregnancy in rats.

The biological activities of free (D3) and sulfoconjugated (SD3) vitamin D3 were compared after 6 weeks of oral administration to D-deficient (-D) female rats which were mated in the meantime. Mothers and pups were sacrificed 1-2 days following parturition and mineral and hormonal plasma status was determined in mothers and bone mineral determinations and bone histomorphometric studies performed. In newborns, plasma levels of Ca, P and 25-hydroxyvitamin D (25(OH)D) were measured. After parturition, -D mothers had decreased body weight (BW) as well as decreased plasma levels of Ca, P and 1,25-dihydroxyvitamin D (1,25(OH)2D) associated with undetectable levels of 25(OH)D. Plasma levels of immunoreactive calcitonin and parathormone, by contrast, were higher than in vitamin D-replete (+D) control mothers. Bone histomorphometric analysis showed osteomalacia and secondary hyperparathyroidism in -D mothers. After parturition, -D +SD mothers had reduced BW compared to D-treated mothers and the plasma parameters measured were abnormal. Almost all bone histomorphometric parameters were found to be intermediate between +D and -D groups without reaching values of +D mothers. By contrast, -D +D mothers had most of the bone formation parameters identical to those of +D mothers. However, bone resorption was still higher while plasma levels of P and 25(OH)D remained slightly, but significantly lower than in +D mothers. In pups, plasma Ca in both D3- and SD3-treated groups was similar to values in +D-treated rats. However, pups from SD3-treated mothers still showed plasma levels of P and 25(OH)D lower than in +D pups. In conclusion, treatment with SD3 in -D mother rats significantly improves the biochemical plasma parameters of pups, but complete normalization can be achieved only in the D3-treated group. Our results show that when administered at equal amounts, SD3 has a much lower biological activity than D3 in -D female rats and cannot therefore replace vitamin D3 particularly during pregnancy.

Animals↗
PubMed1985

Influence of vitamin D on mineral metabolism, hormonal status and bone histology in lactating rats and their pups.

Mineral, hormonal and skeletal changes were determined in vitamin D-deficient (-D) and vitamin D-replete (+D) mother rats and in their litters on day 20 of lactation. These results were compared with those obtained in -D mothers and pups, after giving the mothers an oral supplement (10 i.u. vitamin D3/day) during the period of lactation (20 days). Compared to +D animals, both -D lactating mothers and their pups exhibited extremely low plasma levels of 25-hydroxyvitamin D3 (25-OH-D3), diminished 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and increased levels of immunoreactive parathyroid hormone (iPTH). Vitamin D-deficient mothers also had higher levels of calcitonin and lower levels of prolactin than +D mothers. All -D animals (mothers and pups) showed increased osteoclastic bone resorption and severe osteomalacia as shown by decreased bone ash, decreased calcification rate and increased endosteal osteoid surface, volume and thickness. In mothers treated with vitamin D3 during lactation, nearly all the plasma variables measured, as well as bone histomorphometric features, were normal. In contrast, their pups still showed rickets and osteomalacia, despite normal levels of 25-OH-D3 and calcium in the plasma. These pups had raised plasma levels of 1,25(OH)2D3 and iPTH associated with persistent stimulation of bone resorption. This study showed that (1) severe vitamin D deficiency in lactating rats produced marked osteomalacia and secondary hyperparathyroidism in both mothers and pups, and (2) vitamin D treatment of -D mother rats during lactation (10 i.u. vitamin D3/day) reversed the mineral, hormonal and skeletal abnormalities in mothers but not in pups.

Animal Population Groups↗
PubMed1982

Cholecalciferol sulfate identification in human milk by HPLC.

Synthetic vitamin D3 sulfate was prepared by reacting cholecalciferol with sulfamic acid in pyridine. Vitamin D3 sulfate ammonium salt was purified by crystallisation and transformed in sulfate sodium salt. Homogeneity was controlled by reverse phase high pressure liquid chromatography (HPLC). Purified synthetic vitamin D3 sulfate sodium salt was used as a reference. Milk whey was obtained after protein precipitation by adding ethanol. Vitamin D3 sulfoconjugate was identified in supernatant (lyophylized) after purification by Sephadex LH 20 and HPLC. Milk whey purified fraction obtained exhibited the same ultra-violet absorption (UV) as synthetic vitamin D3 sulfate; after solvolysis, cholecalciferol was liberated from natural and synthetic sulfoconjugate. The results confirmed that vitamin D3 sulfate was present in human milk.

Cholecalciferol↗
PubMed1982

Calcium phosphate metabolism and bone disease in patients with homozygous thalassemia.

Calcium and phosphate metabolism were studied in 22 patients with homozygous thalassemia. The overall results showed no significant difference for serum calcium, phosphorus, alkaline phosphatase, immunoreactive parathyroid hormone, or 25-hydroxyvitamin D between thalassemic and control children. However, during the winter, serum 25-hydroxycholecalciferol levels were very significantly decreased in thalassemic children. A study of the hands showed thin metacarpal cortices related to increased resorption. Histomorphometric study of four iliac bone biopsies showed normal osteoclastic resorption and decreased bone formation. Prussian blue staining and x-ray electron microprobe analysis showed iron deposits inside the bone. Whether this finding is critical in the pathogenesis of the bone disease in unknown.

Adolescent↗