RESUMO

To assess the effect of sympathectomy on rat tooth eruption, the effect of a unilateral superior cervical ganglionectomy (SCGx) on eruption rate of ipsi- and contralateral lower incisors was examined. Two experiments were performed. In a first experiment, the eruption rate of ipsilaterally denervated incisors was similar to that of contralaterally innervated incisors, when assessed for up to 28 days after surgery. In a second experiment, under conditions of unilateral unimpeded eruption of incisors performed ipsilaterally or contralaterally to a unilateral SCGx, a significantly lower eruption rate of denervated incisors at the impeded eruption side, and a significantly higher eruption rate of denervated incisors at the unimpeded side were observed, when computed every 2 days. Significant differences in individual Student's t tests at every time interval occurred mainly during the first and the last week of examination. When average daily eruption rate was computed in weekly intervals, a significant interaction between SCGx and the side of impeded or unimpeded eruption was found in a factorial ANOVA, that is, for each of the 4 weeks of examination, sympathetically denervated incisors showed lower eruption rates at the impeded eruption side, and higher eruption rates at the unimpeded side. These results indicate that incisor eruption is not modified by a local sympathetic denervation unless the contralateral lower rat incisor is cut out of occlusion.

Assuntos

RESUMO

To assess the effect of pharmacological dose of melatonin on bone metabolism in ovariectomized rats, urinary deoxypyridinoline (a marker of bone resorption) and calcium excretion, circulating levels of calcium, phosphorus and bone alkaline phosphatase activity (a marker of bone formation), and bone mineral density (BMD), mineral content (BMC) and bone area (BA) of total body, were measured in adult rats for up to 60 days after surgery. Rats received melatonin in the drinking water (25 microg/ml water) or drinking water alone. Urinary deoxypyridinoline increased significantly after ovariectomy by 51% (30 days after surgery) and by 47% (60 days after surgery). The increase in urinary deoxypyridinoline found 30 days after ovariectomy was not observed in melatonin-treated rats. Urinary calcium concentration was similar in the 4 experimental groups studied, as was the circulating calcium concentration at every time interval examined. Fifteen days after surgery, a significant increase in serum phosphorus and bone alkaline phosphatase levels occurred in ovariectomized rats receiving melatonin as compared to their controls. Sixty days after surgery BMD, BMC and BA decreased significantly in ovariectomized rats, an effect not modified by melatonin. Serum estradiol decreased significantly by 30 days after ovariectomy to attain values close to the limit of detection of the assay by 60 days after ovariectomy. The results support the conclusion that a pharmacological amount of melatonin modifies bone remodeling after ovariectomy and that the effect may need adequate concentrations of estradiol.

Assuntos

RESUMO

To assess the effect of a local sympathectomy on bone metabolism, the effect of a unilateral superior cervical ganglionectomy (Gx) on growth and bone mineral content and density of the ipsi- and contralateral mandibles was examined in female rats. A significant increase in the hemi-mandibular bone ipsilateral to Gx was found as compared to the contralateral, sham-operated side 30 days, but not 15 days, after surgery. Bone mineral content of the hemi-mandibular bones was significantly lower in the side ipsilateral to Gx in the group of rats killed on the 30th day after surgery. Since no difference in areas between innervated and denervated hemi-mandibles was found, bone mineral density was also significantly lower in the hemi-mandible ipsilateral to Gx. The results further support that a regional sympathectomy causes qualitative alterations in bone modeling and remodeling, leading to bone resorption.

Assuntos

RESUMO

Calcium metabolism was studied in 47 patients with borderline or lepromatous leprosy. Total and ionized calcium, phosphorus, creatinine, total alkaline phosphatase, parathyroid hormone (PTH), 25-hydroxy vitamin D [25(OH)D], and 1,25-dihydroxy vitamin D [1,25(OH)2D] were measured in serum; calcium and total hydroxyproline were determined in urine. Total subperiosteal diameter and medullar cavity diameter were measured on an X-ray of the hand of all patients. Average values were within normal ranges for all of the biochemical determinations. Total serum calcium was moderately below the normal range in eight patients but ionized calcium levels were within the normal ranges in all of the patients. Four patients, all of them with lepromatous leprosy, had levels of 1,25(OH)2D higher than normal but none of them was hypercalcemic and PTH levels were within normal range. Although all values were within the normal ranges, lepromatous leprosy patients had lower total calcium, higher alkaline phosphatase, and higher urinary hydroxyproline than borderline leprosy patients (9.1 +/- 0.4 vs 9.4 +/- 0.3 mg%, p < 0.001; 10.3 +/- 2.9 vs 7.4 +/- 2.3 King-Armstrong units, p < 0.02 and 27.2 +/- 12 vs 19.4 +/- 5.6 mg/24 hr, p < 0.02, respectively). No differences were found between patients and controls in the average micrometric measurements of the second metacarpal bone but significant osteopenia was found in 19% of the patients. The main finding of the present study in a representative sample of leprosy patients is that the average total serum calcium was in the lowest limit of the normal range, but the ionized serum calcium was in the middle of the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)

Assuntos

RESUMO

The dual X-ray absorptiometer (DEXA, Hologic ZDR-1000) in a high resolution mode was evaluated for measuring: Area (A), Bone Mineral Content (BMC) and Bone Mineral Density (BMD) in femur and tibia of adults rats at four regions: proximal (L1), diaphysis (L2-L3) and distal (L4). Reproducibility with and without repositioning was evaluated in femur after ten measurements in a water bath at depths between 2.0 and 2.5 cm. The whole coefficient of variation (CV = 100 x SD/mean) of BMD was 0.52% and 0.47% respectively. Accuracy was evaluated by comparing the BMC to bone ash weight. BMC was highly correlated with chemical analysis (r = 0.98, p < 0.001) for femur. The ability to detect changes in BMD was studied by comparing BMD of the right and left femurs and tibias of adult normal males and females rats. No significant differences were found between both sides. Nevertheless, when BMD (X +/- SE) of male and female rats were compared, female rats presented lower BMD at distal femur (0.263 +/- 0.021 vs. 0.315 +/- 0.009, p < 0.05) and proximal tibia (0.259 +/- 0.016 vs. 0.315 +/- 0.013 p < 0.02) than male rats. We also studied the ability to detect BMD changes in abnormal metabolic conditions. SHAM operated rats were compared to ovariectomized (OVX) rats and it was observed that femur of OVX showed a lower distal BMD than SHAM (0.217 +/- 0.005 vs. 0.263 +/- 0.021, p < 0.05). In summary, DEXA is a technique accurate and precise enough to detect changes on BMC and BMD in small animals permitting the experimental study of different metabolic bone conditions.

Assuntos

RESUMO

The dual X-ray absorptiometer (DEXA, Hologic ZDR-1000) in a high resolution mode was evaluated for measuring: Area (A), Bone Mineral Content (BMC) and Bone Mineral Density (BMD) in femur and tibia of adults rats at four regions: proximal (L1), diaphysis (L2-L3) and distal (L4). Reproducibility with and without repositioning was evaluated in femur after ten measurements in a water bath at depths between 2.0 and 2.5 cm. The whole coefficient of variation (CV = 100 x SD/mean) of BMD was 0.52

and 0.47

respectively. Accuracy was evaluated by comparing the BMC to bone ash weight. BMC was highly correlated with chemical analysis (r = 0.98, p < 0.001) for femur. The ability to detect changes in BMD was studied by comparing BMD of the right and left femurs and tibias of adult normal males and females rats. No significant differences were found between both sides. Nevertheless, when BMD (X +/- SE) of male and female rats were compared, female rats presented lower BMD at distal femur (0.263 +/- 0.021 vs. 0.315 +/- 0.009, p < 0.05) and proximal tibia (0.259 +/- 0.016 vs. 0.315 +/- 0.013 p < 0.02) than male rats. We also studied the ability to detect BMD changes in abnormal metabolic conditions. SHAM operated rats were compared to ovariectomized (OVX) rats and it was observed that femur of OVX showed a lower distal BMD than SHAM (0.217 +/- 0.005 vs. 0.263 +/- 0.021, p < 0.05). In summary, DEXA is a technique accurate and precise enough to detect changes on BMC and BMD in small animals permitting the experimental study of different metabolic bone conditions.

RESUMO

Hypocalcemia is a common finding during stress. The objective of this study was to examine: (a) the changes in circulating calcium, parathyroid hormone (PTH) and calcitonin (CT) concentration in rats stressed by being given a subcutaneous injection of turpentine oil, and (b) the involvement of the sympathetic cervical pathway in stress-induced changes of calcium homeostasis. Four hours after receiving turpentine oil or vehicle, rats were subjected either to hypocalcemia, by being given EDTA intraperitoneally, or to hypercalcemia, by being injected CaCl2 intraperitoneally. Significant changes in serum calcium (10% decrease), serum PTH (28% increase) and CT levels (40% decrease) were observed in stressed rats. EDTA administration brought about a significantly greater hypocalcemia, and a higher PTH secretory response in turpentine oil-stressed rats. During stress, the increase of serum calcium after CaCl2 was significantly smaller, and the rise of CT was greater than in controls. In the case of CT the changes were still observed in rats subjected to superior cervical ganglionectomy (SCGx) 14 days earlier. In the case of PTH, the increase found in stressed rats, but not the augmented response after EDTA, was blunted by SCGx. The potentiation of hypocalcemia brought about by turpentine oil was no longer observed in SCGx rats. In vehicle-treated controls, SCGx delayed PTH response to hypocalcemia, but did not affect the increased response of CT to CaCl2 challenge. The results indicate that a number of changes in calcium homeostasis arise during turpentine oil stress in rats. SCGx was effective to modify the set point for PTH release, but played a minor role in affecting the augmentation of CT release during stress.

Assuntos