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Biomedical subjects

M T Pacitti

Publications and source records attributed to M T Pacitti.

28 records · Page 2Linked to original sources
PubMed1990

The effects of oophorectomy on skeletal metabolism.

The effects of oophorectomy on the biological indices of bone remodelling and the time-course of their changes are described. In the first few months following surgical menopause the measurement of the markers of bone remodelling indicates that the increase in osteogenesis is delayed compared with that of bone resorption; this prevalence of destruction over new bone deposition justifies the deficiency of skeletal balance, shortly after acute oestrogen deficiency. The changes in bone remodelling are accompanied by an increase in serum calcium while serum immunoreactive parathyroid hormone levels remain unchanged or even decrease, suggesting a shift to right of the parathyroid gland set-point. The reasons for the negative skeletal balance after oophorectomy might be sought therefore at bone tissue level, even if changes in responsiveness and/or of the parathyroid gland set-point could also be contributory.

Bone and Bones↗
PubMed1990

Two-site assay of intact parathyroid hormone in primary hyperparathyroidism: studies in basal conditions, following adenoma removal and during calcium and EDTA infusion.

This study has been carried out in order to investigate parathyroid hormone secretion in patients with primary hyperparathyroidism in basal conditions, during stimulation and suppression tests and following successful surgery. Parathyroid gland secretory activity has been evaluated by a highly sensitive immunoradiometric assay (IRMA) which detects only the biologically intact active hormone and with a well established midmolecule (MM) PTH RIA. There was a good correlation between the two assays in basal state (r = 0.779); however the correlation found between serum PTH levels and total calcium values was better for the intact hormone (P less than 0.001) than for the radioimmunoassay (P less than 0.05). Twenty-four hours following surgery, serum intact PTH levels were in all patients less than 10 pg/ml while midmolecule PTH was still detectable, thereafter remaining at a higher level during the next six days. Serum IRMA PTH levels fell rapidly in response to the increase in serum calcium, then there was a trend to reach a plateau; serum midregion PTH levels fell, although slower than those of intact hormone. The percent increase obtained for serum intact hormone levels was higher than that observed for MM RIA, following EDTA stimulation. The results obtained indicate that the assays of intact and midmolecule parathyroid hormone clearly reflect different aspects of hormone metabolism 'in vivo' and may prove therefore to be useful for its investigation in various calcium disorders.

Adenoma↗
PubMed1989

Clinical value of the measurement of bone remodelling markers in primary hyperparathyroidism.

This study was performed in order to evaluate the clinical usefulness of the measurement of total serum alkaline phosphatase activity (AP), serum osteocalcin (BGP) and urinary hydroxyproline (OHPr) in assessing bone remodelling in primary hyperparathyroidism. Thirty-two patients with primary hyperparathyroidism were included in the study. No statistically significant differences were observed between the mean values of Z-scores obtained for each marker. Furthermore, an inverse correlation was found between percentage of bone mineral content at the distal radius and both BGP (r = -0.57; p less than 0.05) and AP (r = -0.49; p less than 0.05). The results obtained demonstrate that, contrary to other metabolic bone diseases (e.g. Paget's disease of bone), all three markers examined may be used in clinical practice to evaluate the entity of skeletal turnover in primary hyperparathyroidism.

Adult↗
PubMed1989

Studies on citrate metabolism in normal subjects and kidney stone patients.

The study was carried out in order to investigate citrate metabolism (i.e. serum levels, filtered load, tubular reabsorption, total and fasting urinary excretion) in a large group of normal subjects (n = 39) and kidney stone patients (n = 45). We found that mean serum citrate levels and filtered loads were similar in the two groups studied. On the other hand, both the 24-hour urinary citrate and the fasting citrate/creatinine ratio were significantly reduced, whereas the mean tubular reabsorption of citrate appeared to be significantly increased in kidney stone patients in respect to control subjects. A good correlation was found between the fasting and the 24-hour citrate/creatinine ratio in both normal subjects (r = 0.84, p less than 0.001) and kidney stone patients (r = 0.89, p less than 0.001). Our data indicate that the kidney appears to be involved in the pathogenesis of hypocitraturia in kidney stone patients and that a substantial proportion of these patients show a reduced urinary excretion of citrate. Finally, the evaluation of the fasting citrate/creatinine ratio may replace the measurement of the substance on the basis of a 24-hour urine collection.

Adolescent↗
PubMedDate not supplied

Conventional and new diagnostic applications of a two-site immunochemiluminometric assay for parathyroid hormone.

This investigation was carried out to evaluate the clinical utility and diagnostic value of serum intact PTH measurement using a recently introduced immunochemiluminometric assay (ICMA). Studies were carried out in 42 normal subjects, 24 patients with primary hyperparathyroidism, 21 patients on chronic maintenance hemodialysis, 8 patients with postsurgical hypoparathyroidism, 7 patients with cancer hypercalcemia and 6 patients with osteomalacia. A good correlation was found in normal subjects between serum ICMA PTH levels and both intact PTH measured by a two-site immunoradiometric assay (n = 42, r = 0.67, p less than 0.001) and a widely used midmolecule radioimmunoassay (n = 21, r = 0.78; p less than 0.001). Similar good correlations were found in primary hyperparathyroidism patients (IC-MA vs immunoradiometric assay r = 0.74; p less than 0.001; ICMA vs midmolecule assay r = 0.77; p less than 0.001). As far as the hypercalcemic conditions were concerned, in 5 patients with mild primary hyperparathyroidism, ICMA PTH levels were in the upper range of those found in normal subjects, even though they were inappropriately high in respect to serum calcium values. However, serum ICMA PTH levels were clearly suppressed or undetectable in the majority of patients with cancer hypercalcemia or postsurgical hypoparathyroidism. Following calcium and EDTA infusions in patients with primary hyperparathyroidism, the behaviour of ICMA PTH levels in general parallelled that of immunoradiometric PTH assay, thus indirectly suggesting the ability of the method to measure the intact molecule.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMedDate not supplied

Parathyroid storm: immediate recognition and pathophysiological considerations.

A 56-year-old white man was referred for evaluation of severe hypercalcemia following a three-week history of progressive weakness, nausea, and depression. Initial laboratory results showed serum total and ionized calcium (Ca++) values of 5.3 and 2.6 mmol/l, respectively. A short intact PTH assay was immediately performed and an extremely high value was obtained in just 30 min (1315 ng/l, normal values 6.4-70.4). The patient was therefore treated with saline solution and with salmon calcitonin (1200 IU/day, half by continuous i.v. infusion and half by i.m. route) for 10 days. There was a sudden decrease of both Ca++ and intact PTH during the first six days; then there was a trend to reach a steady-state until parathyroidectomy was performed. After withdrawal of calcitonin therapy it was possible to observe a positive uncoupling between bone formation (serum alkaline phosphatase and osteocalcin) and resorption (serum tartrate-resistant acid phosphatase) markers. On day 35 the patient underwent neck exploration, and an enlarged lower left parathyroid gland was removed that on macroscopic examination revealed the presence of a haemorrhagic cyst; microscopic appearance was suggestive of a previous glandular infarction. This is the first time the daily clinical course of a parathyroid crisis has been documented. Furthermore, changes of biomarkers of bone turnover following calcitonin therapy show that high doses of the hormone may cause a prolonged positive uncoupling of the two processes of bone remodeling.

Acid Phosphatase↗
PubMedDate not supplied

Exogenous glucocorticoids affect in different way the various phases of bone formation in postmenopausal patients.

BACKGROUND: To determine the effect of glucocorticoid excess on the most important circulating markers of bone formation in postmenopausal treated patients. METHODS: The study included 15 postmenopausal women taking glucocorticoids for various medical conditions and two groups of 30 healthy premenopausal and 28 age-matched postmenopausal women as controls. Osteoblastic activity was assessed by measuring both serum levels of osteocalcin (BGP) (N-tact Osteo SP, Incstar Co.) and the bone-specific isoenzyme of alkaline phosphatase (BAP) (Alkphase-B, Metra Biosystems). RESULTS: The mean values of serum BGP found in patients taking steroids were significantly reduced as compared to those found in both fertile and postmenopausal women (p < 0.0001). The mean serum levels of BAP were significantly increased in treated patients as compared to premenopausal women (p < 0.0001), while no significant difference was found between patients and age-matched postmenopausal women. Similar results were also obtained when individual values of both serum BAP and BGP were expressed as standard units in comparison to values obtained in fertile subjects (T-score) or postmenopausal subjects (Z-score). CONCLUSIONS: Steroid therapy in postmenopausal patients differentially affects the various phases of bone formation. Measurement of serum BGP may represent a reliable parameter for monitoring bone formation in postmenopausal treated patients.

Aged↗
PubMedDate not supplied

[Primary hyperparathyroidism: the recent findings].

Primary hyperparathyroidism is a quite frequent disease, the incidence of which has been found to increase over the past two decades. At the same time there has been a remarkable change in its clinical presentation; therefore this endocrine disorder earlier considered rare but almost always associated with complications, now appears a quite common and uncomplicated disease. In our series of 150 patients diagnosed between 1966 and 1989 the female/male ratio was found to be 1.77. The ratio has significantly increased (2.09), beginning from 1983; this was mainly due to the availability of a bone densitometer at our Mineral Metabolism Service with consequent greater demand of serum calcium determination as a part of routine metabolic screening for prevention of postmenopausal osteoporosis. Whilst the percentage of patients with renal manifestations of the disease has not significantly changed during these years, the amount of asymptomatic patients (yrs 1966-1983 = 3.7% vs yrs 1984-1989 = 39.7%) has progressively increased to the detriment of patients with skeletal symptoms. Serum intact parathyroid hormone determination by immunoradiometric assay (and possibly by immunochemiluminometric assay) seems to have overcome some of the methodological problems inherent in conventional radioimmunoassay. Surgical treatment of primary hyperparathyroidism is safe and highly effective in experienced hands. Recurrence has been observed only in three cases after resection of parathyroid adenoma, thus indirectly supporting a monoclonal origin of the tumor. Medical behavior (conservative or surgical management) in respect to patients with the mild or asymptomatic form of the disease, especially when diagnosed in old age, is uncertain at this point in time. Future prospective studies carried out on a large number of patients are needed to better clarify this issue.

Humans↗