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Biomedical subjects

P Ammann

Publications and source records attributed to P Ammann.

68 records · Page 4Linked to original sources
PubMed1993

Alterations of calcium and phosphate metabolism in primary hyperparathyroidism during pregnancy.

Primary hyperparathyroidism (PHP) is rare during pregnancy and has been claimed to be associated with significant increase of neonatal morbidity and mortality. Whether the well recognized changes in calcium (Ca) and phosphate (Pi) homeostasis occurring in pregnancy might influence the biochemical expression of PHP is unclear. We evaluated biochemical parameters of calcium and phosphate metabolism in two cases of PHP in pregnancy diagnosed in the third trimester (patient 1) and in the second trimester (patient 2). Both patients displayed increase in protein-adjusted plasma Ca, bone resorption evaluated by the fasting urinary Ca-to-creatinine ratio, renal tubular reabsorption of Ca, urinary cAMP excretion and decrease in renal tubular reabsorption of Pi. These alterations were identical to those found in 12 non-pregnant women with PHP. The biochemical expression of PHP did not change after delivery in patient 1. This patient underwent the excision of a 1 g parathyroid adenoma on the 13th day after delivery, which led to normalization of all biochemical parameters. The lowest plasma Ca of the newborn of patient 1 was 2.02 mM 72 hours after birth. Thus, the results indicate that these two pregnant women with PHP displayed biochemical alterations of calcium and phosphate metabolism similar to those observed in non-pregnant women with primary hyperparathyroidism.

Adult↗
PubMed1992

Sequential and precise in vivo measurement of bone mineral density in rats using dual-energy x-ray absorptiometry.

In the design of new strategies for the treatment of osteoporosis, noninvasive, precise, and sensitive bone mass measurement capable of detecting changes over short periods of time in small animals is essential. Most of the models described thus far require the sacrifice of the animals and/or display low reproducibility. Using a dual-energy x-ray absorptiometer (DEXA; Hologic QDR-1000) in an ultrahigh-resolution mode, we measured bone mineral density (BMD) in rats at the levels of lumbar spine (L1-4), proximal tail (caudal vertebrae C2-4), and tibia. Accuracy was evaluated by measuring the mineral content of bone powder capsules (within the range of rat vertebrae BMD), under 0.5-3 cm water to mimic variations in soft tissue thickness. The bone powder capsule mineral content was highly correlated with chemically determined hydroxyapatite content (r = 0.999). In vivo reproducibility was evaluated by calculating the coefficient of variation (CV = 100 x SD/mean) of four to six BMD measurements, each time with repositioning, in seven rats (220-500 g body weight). CV was 1.36 +/- 0.32% (x +/- SD) for lumbar spine, 0.66 +/- 0.50% for proximal tail, and 1.12 +/- 0.45% for tibia. The ability to detect BMD changes was investigated by measuring BMD before and every 4 weeks after ovariectomy (OVX) in 270 g rats, pair fed during the whole experiment. Compared with sham-operated control animals, a highly significant difference in lumbar spine BMD was observed 4 weeks after OVX, which reached a maximum by 8 weeks and remained stable thereafter. At the level of the proximal tibia, the difference was maximal 4 weeks after OVX.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1992

Comparison of a rapid (2-h) versus a slow (24-h) infusion of alendronate in the treatment of hypercalcemia of malignancy.

Alendronate (aminohydroxybutylidene bisphosphonate) is a potent inhibitor of bone resorption but the role of the duration of intravenous infusion in its efficacy profile is unclear. In a two-centre, parallel, randomized, double-blind study, 20 patients with tumoral hypercalcemia received a single 10-mg i.v. infusion over either 2 h (group A, n = 10) or 24 h (group B, n = 10). Recurrences (n = 6) were retreated using the same regimen. Pretreatment plasma calcium (Ca) was 3.32 +/- 0.08 mM (mean +/- SEM) for all patients. Treatment A and B were associated with similar temporal profiles for onset, time to reach normocalcemia, (6 vs 5 days), nadir (day 6: 2.45 +/- 0.06 vs 2.43 +/- 0.08 mM) and time to relapse (day 21). Normocalcemia (2.15-2.55 mM) was achieved in seven (A) and nine (B) patients with other cases being partial responders (Ca: 2.65-2.76 mM). A significant decrease of urinary calcium and hydroxyproline excretion and a significant increase of PTH accompanied Ca normalization in both groups. Ca response was 50% lower on 2nd treatment with alendronate. Both treatments were well tolerated with transient mild fever being the most common adverse experience. In conclusion, whether infused over 2 or over 24 h, a single dose of 10 mg alendronate led to normalization of tumoral hypercalcemia in a large majority of cases.

Aged↗
PubMed1988

Influence of the disaccharide lactitol on intestinal absorption and body retention of calcium in rats.

Various sugars are known to stimulate intestinal calcium absorption by a mechanism that is still poorly understood. One of those, the disaccharide 4-gal-actosyl-sorbitol (lactitol), is only metabolized in the large intestine, where it is converted into acidic residues. We investigated the effect of this compound on net intestinal absorption and body retention of calcium in rats. Because dietary calcium is in a poorly absorbable form when it reaches the large intestine, attempts were made to modify the absorption of calcium present in the large intestine contents by administering lactitol. Net intestinal absorption and body retention of calcium were significantly increased by 2.5 g lactitol/(kg b.w.d) given by a gavage over a 7-d period. This was associated with a lower pH and a better availability to absorptive systems of calcium present in the large intestine contents. The results indicate that in rats lactitol given chronically increases net intestinal absorption of calcium with a subsequently more positive calcium balance.

Animals↗
PubMed1986

Calcium absorption in the rat colon measured in vivo.

Calcium absorption in the large intestine was studied under physiological conditions in the rat. When 45Ca was administered directly into the caecum, the isotope was significantly absorbed. This absorption was modulated by dietary Ca and Pi as well as by the 1,25(OH) D3 status. On the other hand, calcium coming from the food, either as 45Ca or as 40Ca, was not absorbed to a significant amount. When the absorption of 45Ca from the caecal content was assessed in duodenal loops, less 45Ca was absorbed when the isotope was administered orally than when it was added to the caecal content. Thus, the fact that oral Ca is not absorbed in the colon despite the efficient Ca transport system of this part of the intestine may be due to the transformation in the digestive tract of Ca from an absorbable into a non-absorbable form.

Administration, Oral↗
PubMed1986

Calcium absorption in rat large intestine in vivo: availability of dietary calcium.

Calcium absorption in the large intestine of the rat was investigated in vivo. After a single injection of 45CaCl2 into the cecum, 26.0 +/- 2.5% (mean +/- SE, n = 9) of the 45CaCl2 injected disappeared. This absorption was modulated by 1,25-dihydroxyvitamin D3, increased to 64.0 +/- 4.2% under a low-Ca diet, and increased under low-Pi diet. In contrast, when the difference of nonradioactive Ca in the cecal content and the feces was measured, only 4.1 +/- 4.6% (not significant) was absorbed. Secretion of intravenously injected 45Ca into the lumen was small and not altered by any of the conditions tested. When cecum contents were placed into duodenal tied loops, 14 +/- 6.2% were absorbed in situ when 45Ca was given orally, whereas when 45Ca was directly added to the content 35.6 +/- 4.6% were absorbed (P less than 0.02). These results indicate that the large intestine has an important vitamin D-dependent Ca absorptive system detectable if 45Ca is injected into the cecum. However, it is not effective in vivo because the Ca arriving in the large intestine appears to be no longer in an absorbable form.

Animals↗
PubMedDate not supplied

Hypercalcemia and hyperosteolysis in vitamin D intoxication: effects of clodronate therapy.

Vitamin D intoxication is a rare cause of hypercalcemia, which is associated with severe and prolonged morbidity. Hypercalcemia and/or hypercalciuria are the consequence of increases in both intestinal absorption and bone resorption. We report on 7 cases of vitamin D overdose (25-hydroxyvitamin D: 710 +/- 179 nmol/l; normal range: 20-90). The indications for vitamin therapy were osteoporosis (5), hypoparathyroidism (1), and osteomalacia (1). Enhanced bone resorption was demonstrated by increased fasting urinary calcium excretion (0.192 +/- 0.067 mmol/l GFR, normal < 0.045). Sequential biochemical measurements in the hypoparathyroid patient showed the persistence of abnormally elevated fasting urinary calcium and of serum 25-hydroxyvitamin D concentrations, even after normalization of plasma calcium, emphasizing that enhanced bone resorption is a prominent feature of vitamin D action. The intravenous administration of a single infusion of the bisphosphonate clodronate to 3 patients led to a correction of hypercalcemia/hypercalciuria, whereas prednisone therapy given to 2 other cases barely affected the abnormal biochemical values. These results indicate that enhanced bone resorption encountered in vitamin D intoxication could be favorably influenced by bisphosphonate treatment.

Adult↗