Oral aluminum administration to uremic, hyperparathyroid, or vitamin D-supplemented rats

In the present study, the role of factors was investigated that could possibly lead to changes in plasma and tissue aluminum (A1) concentrations following oral A1 exposure. In chronically uremic rats that received an oral A1 supplementation of 150 mumol/g diet during 4 weeks, a significant increase in mean (+/- SEM) liver A1 content was observed when compared to sham-operated, pair-fed control rats (9.9 +/- 2.0 versus 4.8 +/- 0.65 nmol/g wet weight, p less than 0.02). No such difference was found in non-A1-supplemented rats. Plasma A1 and the A1 content of other organs studied except muscle were not increased in uremic as compared to control animals. In rats with hyperparathyroidism secondary to a calcium-poor diet, mean liver and bone A1 content was significantly decreased when not A1-exposed (2.5 +/- 0.13 and 62 +/- 5.5 nmol/g, respectively) and normal when A1-supplemented (4.7 +/- 0.59 and 120 +/- 23 nmol/g, respectively) as compared to normal control rats without A1 supplementation (5.1 +/- 1.5 and 170 +/- 17 nmol/g, respectively). However, in the hyperparathyroid rats, mean plasma A1 concentration was higher than in control, euparathyroid rats. In rats with exogenous hyperparathyroidism (parathyroid extract) a significant increase in liver A1 content was observed when compared to control rats (8.1 +/- 0.95 versus 5.3 +/- 0.53 nmol/g, p less than 0.05). In A1-supplemented normal rats treated with 1,25(OH)2 vitamin D3 during 4 weeks, liver A1 content was significantly lower than in control rats receiving vehicle solution only (2.9 +/- 0.76 versus 5.7 +/- 0.59 nmol/g, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Total parathyroidectomy and delayed parathyroid autotransplantation using a simplified cryopreservation technique: human and animal studies

Following earlier studies using a simplified cryopreservation method in rats, we report the successful use of this technique in a hemodialysis patient who had previously undergone total parathyroidectomy. In additional studies, parathyroid glands from rats were conserved by this rapid freezing procedure after total parathyroidectomy. Six weeks after parathyroid autotransplantation the animals were submitted to a low-calcium diet and their parathyroid gland function compared to that of rats that had previously undergone sham operation, immediate autotransplantation, or delayed autotransplantation using the classical cryopreservation method. With both cryopreservation techniques, plasma calcium, phosphorus, and 1,25 (OH)2 vitamin D concentrations after low-calcium diet were similar although results were less satisfactory than with immediate autotransplantation or after sham operation. We suggest that this simplified cryopreservation technique, developed in rats, yields functioning parathyroid gland tissue and can be successfully used in the human.

Parathyroid function and lipid metabolism in the rat

The present investigation in experimental animals was designed to obtain further insight into the possible role of parathyroid hormone (PTH) in lipid metabolism. An endogenous hyperparathyroid state was induced in rats by a calcium-poor diet. This type of hyperparathyroidism was associated with a significant increase in serum cholesterol and triglyceride concentrations, a significant decrease in the serum clearance rate of intravenously infused Intralipid and a significant increase in hepatic tissue triglyceride content as compared to the values obtained in control animals. An exogenous type of hyperparathyroidism (parathyroid extract injections) was also accompanied by a slight increase in serum cholesterol and triglyceride concentrations as well as a decrease in plasma postheparin lipolytic activity (PHLA), but the changes did not reach the level of statistical significance. In the aparathyroid state, a significant decrease in serum cholesterol and triglyceride concentrations and a significant increase in plasma PHLA were observed as compared to control rats. In additional studies, it could be demonstrated that the endogenous hyperparathyroid state was not associated with increased intestinal absorption of [3H]triolein as compared to control animals. Furthermore, the hepatic triglyceride secretion rate in these hyperparathyroid rats was significantly lower than in normal rats. In conclusion, hyperparathyroidism induces an increase in serum cholesterol and triglyceride concentrations, the latter being due to decreased peripheral removal. The aparathyroid state induces opposite changes. Thus, normal parathyroid function is required for normal lipid metabolism in the rat.

Successful parathyroid gland autotransplantation in the rat using a simplified cryopreservation technique

In the present work a simplified technique for cryopreservation of parathyroid glands was compared to the generally used technique needing a programmed freezer. Four groups of rats had total parathyroidectomy. In two of them the glands were cryopreserved and reimplanted 10 days after ablation. The other two groups had, respectively, immediate parathyroid autotransplantation and no autotransplantation. During a follow-up of 60 days, plasma calcium remained low and plasma phosphorus elevated in all aparathyroid rats of the last group. In the group of rats with immediate parathyroid reimplantation, both mean plasma calcium and phosphorus values rapidly returned to the normal values observed before operation. In the rats that had the simplified parathyroid cryopreservation technique, mean plasma phosphorus also returned to the normal range and mean plasma calcium to nearly normal. However, in the group of rats with the classical cryopreservation method, the mean plasma calcium and phosphorus levels remained far from normal in the majority of animals. It was concluded that parathyroid glands of the rat could be successfully autografted after previous freezing using a simplified cryopreservation technique. The results obtained were comparable with, even though not as perfect as, that observed after immediate autotransplantation. If suitable for human parathyroid gland fragments, this technique would allow a more general application of parathyroid tissue cryopreservation.

Carnitine improves lipid anomalies in haemodialysis patients

51 chronic haemodialysis patients with hypertriglyceridaemia were given a daily oral dose of 2.4 g D,L-carnitine for 30 days to investigate a possible hypolipaemic effect. After 30 days' D,L-carnitine treatment the mean (+/- SEM) serum triglyceride concentration had decreased significantly from 3.50 +/- 0.39 to 2.87 +/- 0.27 mmol/l. Serum total cholesterol did not change. However, HDL cholesterol increased significantly from 0.89 +/- 0.05 to 1.35 +/- 0.07 mmol/l. This decrease in serum triglycerides and return of HDL cholesterol to normal levels in haemodialysis patients may be the result of correction of carnitine deficiency. Such treatment could reduce the risk factors for atherosclerosis and coronary-artery disease in uraemic patients.