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A Bollati

Publications and source records attributed to A Bollati.

At least 19 recordsLinked to original sources
PubMed2004

Effects of the selective estrogen receptor modulator LY117018 on growth hormone secretion: In vitro studies.

Sex steroids play an important role in modulating pulsatile growth hormone (GH) release, acting at both hypothalamic and pituitary level in both humans and experimental animals. Selective estrogen receptor modulators (SERMs) act as either estrogen receptor agonists or antagonists in a tissue-selective manner. In postmenopausal women, serum GH levels correlate positively with endogenous estradiol levels and insulin-like grwoth factor-I (IGF-I) is positively related to bone mineral density (BMD) at the spine and hip. The aim of the present study was to evaluate, for the first time, the direct effect of LY117018, an analog of raloxifene, on GH secretion from both human and rodent pituitary cells in vitro. Our results demonstrated that pharmacological concentrations of the raloxifene analog LY117018 can stimulate GH secretion through a direct action on the pituitary. LY117018 also showed an estrogen-like activity, inducing the proliferation of rat pituitary GH-secreting adenomatous cells (GH1).

Adenoma↗
PubMed2001

Differential inhibition of growth hormone secretion by analogs selective for somatostatin receptor subtypes 2 and 5 in human growth-hormone-secreting adenoma cells in vitro.

Somatostatin (SRIH), a cyclic tetradecapeptide hormone originally isolated from mammalian hypothalamus, is a potent suppressor of pituitary growth hormone (GH) secretion. SRIH acts through a family of G-protein-coupled membrane receptors containing seven transmembrane domains. Five genes encoding distinct SRIH receptor (SSTR) subtypes have so far been cloned in human and other species and termed SSTR1-5. In human somatotrophe pituitary adenomas GH secretion is controlled by both SSTR2 and SSTR5. However, in clinical practice only somatostatin analogs selective for SSTR2 (octreotide and lanreotide) are available. This may explain why clinical and in vitro responses to these analogs in acromegaly are only partial. In this study, we investigated the inhibitory effect of two new SRIH analogs with high selectivity for SSTR2 (NC-4-28B) and SSTR5 (BIM-23268) and compared it to that of native somatostatin (SRIH-14) on a large number of GH-secreting adenomas obtained by transphenoidal neurosurgery. Tissues from 16 adenomas were enzymatically dispersed and plated in 24-well dishes at 50,000 cells/well. After 3 days, groups of three wells were incubated for 4 h with medium alone, SRIH-14 or analogs NC-4-28B or BIM-23268, at the concentrations of 0.01, 0.1 and 1 microM. Our results show that 9 out of 16 adenomas were responsive (GH suppression: 20-40% vs. control, p < 0.05) to SRIH. In this group only 4 adenomas showed similar responses to both selective analogs, with 2 nonresponders (expression of other SRIH receptor subtypes) and 2 responders (concomitant expression of SSTR2 and SSTR5) to both analogs. GH release was selectively inhibited by NC-4-28B in 3 adenomas and by BIM-23268 in the remaining 2 adenomas, suggesting predominant expression of SSTR2 and SSTR5, respectively. SRIH failed to inhibit GH release in 7 adenomas (43%). Interestingly, in that group a better inhibitory effect was obtained with BIM-23268 (5 out of 7 adenomas) than with NC-4-28B, suggesting expression of a few SSTR5 receptors only, or of both SSTR2 and SSTR5, respectively. We conclude that the availability of somatostatin analogs selective for SSTR5 will enhance the treatment potency and spectrum in acromegaly.

Adenoma↗
PubMed1999

Emergent decompressive craniectomy in patients with fixed dilated pupils due to cerebral venous and dural sinus thrombosis: report of three cases.

OBJECTIVE AND IMPORTANCE: Cerebral venous and dural sinus thrombosis is a rare cause of stroke. Although morbidity and mortality have greatly decreased in recent years as a result of early diagnosis and timely medical treatment, when coma occurs the prognosis remains poor. We evaluated whether emergent decompressive craniectomy has a role in the treatment of patients with brain herniation from dural sinus thrombosis and hemorrhagic infarct. CLINICAL PRESENTATION: Three patients developed large hemorrhagic infarct with coma and bilaterally fixed and dilated pupils resulting from aseptic dural sinus thrombosis. INTERVENTION: Two patients underwent emergent surgical decompression as soon as brain herniation developed, and these patients had complete functional recovery. One underwent delayed surgical decompression and remained severely disabled. CONCLUSION: Our results provide preliminary evidence that emergent decompressive craniectomy is effective in patients with brain herniation from dural sinus thrombosis, provided that the clinical onset is recent. We therefore recommend consideration of this aggressive surgical technique for such patients, who may survive with good outcomes.

Adult↗
PubMed1998

Effects of chronic nimodipine on working memory of old rats in relation to defects in synaptosomal calcium homeostasis.

The present study was designed to investigate whether chronic (from 12 to 23 months of age) dietary treatment with the L-type Ca2+ channel blocker nimodipine (30 mg/kg body weight) enhances the cognitive behavior of aged animals and whether such a treatment would have long-term effects on the mechanisms of Ca2+ regulation in synaptic terminals from the aged rat brain. Cognitive behavior was evaluated in an 8-arm radial maze in 6 test series comprising a total of 105 test sessions, with intervals of no training between series. Nimodipine-treated rats performed better than vehicle-treated, aged-matched controls in all the test series, making more correct choices every time a new series was initiated. However, differences between nimodipine- and vehicle-treated rats were most remarkable in the last three test series, when the rats were 19 to 22 months. In these series 74% of the nimodipine-treated rats were able to perform the task in 4 to 9 test sessions whereas only 12%, 14% or none of the control rats learned the task. To study Ca2+ regulation in synaptosomes derived from cerebral cortex and hippocampus, we analyzed 45Ca2+ accumulation as well as the levels of the Ca2+-binding proteins calbindin-D28K and calreticulin by Western blotting. Nimodipine administration had no effect on hippocampal synaptosomes but increased the levels of calbindin-D28K and calreticulin in cerebral cortex preparations. These results indicate that chronic nimodipine treatment from 12 to 23 months of age prevents age-induced learning deficits without showing any signs of toxicity, and that these effects are associated with a small increase in the levels of synaptosomal Ca2+-binding proteins from cerebral cortex. The up-regulation of these proteins might provide a link between the long-term effects of nimodipine on gene expression and learning ability in old rats.

Aging↗
PubMed1997

Inhibitory effects of galanin on growth hormone (GH) release in cultured GH-secreting adenoma cells: comparative study with octreotide, GH-releasing hormone, and thyrotropin-releasing hormone.

The aim of the present study was to characterize in a large series (N = 12) of cultured somatotrope adenomas the in vitro effects of the neuropeptide galanin on growth hormone (GH) secretion. This was contrasted with two peptides known to be GH secretagogues (GH-releasing hormone [GHRH] and thyrotropin-releasing hormone [TRH]) and a peptide with a known GH-inhibitory effect (the somatostatin analog octreotide). Groups of three wells were incubated for 4 hours with growth medium alone (control incubation), galanin, GHRH(1-29)NH2, TRH, or octreotide. Galanin and octreotide were applied at concentrations of 0.1, 1, and 10 mumol/L, and GHRH and TRH at concentrations of 0.01, 0.1, and 1 mumol/L. Galanin was able to inhibit GH release in nine of 12 cultured somatotrope adenoma cells. This inhibitory effect was clearly dose-dependent in five adenomas. Overall, the mean GH nadir after galanin was -36.1% in nine responder adenoma cultures versus control wells. Octreotide inhibited GH release in five of eight cultured somatotrope adenoma cells. The mean GH nadir after octreotide was -32.7% in five responder adenoma cultures compared with control wells. GHRH and TRH were able to stimulate GH release, respectively, in seven of 11 and in six of seven cultured somatotrope adenoma cells. The mean GH peaks after either GHRH or TRH in responder adenoma cultures were, respectively, +71.5% and +143.7% compared with levels in the control wells. In conclusion, the consistency and potency of the in vitro GH-inhibitory effect of galanin in a large series of somatotrope adenomas are at least similar to those of the most effective available GH-lowering agent, the somatostatin analog octreotide.

Adenoma↗
PubMed1995

Characterization of the paradoxical growth hormone inhibitory effect of galanin in acromegaly.

Galanin is a 29-amino acid straight-chain biologically active peptide which has been found to decrease circulating GH levels in some acromegalic patients, whereas is able to increase GH secretion in normal subjects. The aim of our study was to ascertain the incidence, entity and mechanism of the paradoxical GH inhibitory effect of galanin in acromegaly also looking at possible correlations between the GH responses to galanin and the main clinical and biochemical features of the patients. Finally, the effects of either successful or unsuccessful neurosurgical intervention on the GH inhibitory effect of galanin in acromegaly were investigated. A series of 23 consecutive patients with active acromegaly seen at the Endocrine Section of the Department of Internal Medicine of the University of Brescia (Italy) between 1991 and 1994 was examined. The acromegalic patients were subdivided in group 1 (i.e. patients who were 1) untreated, 2) evaluated before surgery, and 3) not cured after surgery and radiotherapy) and group 2 (i.e. surgically cured). All patients were submitted at least once to the following biochemical and radiological evaluations: 1) baseline serum insulin-like growth factor-I and PRL samples, 2) iv infusion of synthetic porcine galanin (500 micrograms in 100 mL saline) from -10 to 30 min, 3) iv bolus injection of TRH (200 micrograms) at time zero, 4) oral glucose tolerance test (75 g glucose, orally) at time zero, and 5) magnetic resonance of the pituitary sella. Adenomatous tissue obtained during neurosurgery in four patients was cultured in vitro, and the effect of the addition of galanin in the culture medium on GH secretion was tested. During galanin infusion in 19 of 21 group 1 patients, serum GH levels were lower with respect to baseline (range of GH decrease, -6.2 to -85.4% with respect to basal levels). During galanin infusion, no reductions in GH levels were observed in the acromegalic patients cured after neurosurgery (group 2); on the contrary, 6 of 7 patients displayed a normal stimulatory response to galanin (range of GH increase, +120-1533.3% of the basal level). A significant correlation between the percent decrease in GH levels after galanin treatment and the percent increase after TRH was found in group 1 patients (r = -0.783; P < 0.05). In three of the four adenomas examined, galanin determined a clear decrease in GH secretion (mean nadir, 63.3 +/- 12% of the baseline secretion rate). In conclusion, we demonstrated that the large majority of numerous patients with active acromegaly show a decrease in serum GH levels after galanin administration.(ABSTRACT TRUNCATED AT 400 WORDS)

Acromegaly↗
PubMed1993

Parapharyngeal space lesions syncope-syndrome. A newly proposed reflexogenic cardiovascular syndrome.

An intense vaso-vagal reaction characterizes those reflex cardiovascular syncopes in which the glossopharyngeal nerve constitutes the main afferent nerve pathway. In these syndromes, afferent fibres of the glossopharyngeal nerve project from the baroreceptorial area to the medullary cardiac and vasomotor centres, from which efferent fibres descend into the vagus. The most common reflex cardiovascular syndromes linked to the IX nerve are carotid sinus syndrome (CSS) and glossopharyngeal neuralgia-asystole syndrome (GNS). Eleven male patients (mean age 65.4 years) with recurrent and severe vaso-vagal attacks are described. The episodes were characterized by asthenia and general malaise, pallor, sudation, unrecordable or very low (40-60 mmHg) arterial blood pressure, mental disorientation and/or syncope. The admission diagnosis in these patients was CSS, but the clinical picture was quite different from classic CSS: triggering factors were not present, vasovagal episodes were longer, syncopes were more frequent and severe and VVI pacing was ineffective. Further investigation, including computerized tomography, showed in all patients a malignant or benign pathological growth occupying and compressing the parapharyngeal space. The authors think that the symptoms exhibited by their patients may be attributed to parapharyngeal space involvement. The pathogenetic mechanism of syncope in these cases could be similar to that occurring in GNS except for the absence of neuralgia itself. Surgical carotid sinus denervation or A-V sequential DDD pacing were ineffective in completely controlling symptoms. Intracranial section of the IX nerve appears to be the most effective mechanism for controlling the syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The role of the intercellular matrix in dermal calcinosis of the CRST syndrome. An electron-microscopic study.

We performed an electron-microscopic study on calcium deposits in two patients with calcifying scleroderma (CRST syndrome). Calcium deposits were detected both intracellularly in the mitochondria of phagocytic cells and extracellularly. Needle-like crystals measuring up to 4,500 A in length and approximately 60 A in width were present in both the Von Kossa-positive regions and the apparently normal dermal areas around the calcification sites. Although the fibrillar matrix's ultrastructure was normal, hollow oxytalan fibrils were detected. Slightly electron-opaque, star-shaped material was observed among the fibrillar component of the matrix (matrix granules), which is the ultrastructural expression of some types of proteoglycans containing keratan sulphate and chondroitin sulphate. These granules cannot be detected in normal dermis. The extrafibrillary calcium deposits on these mucopolysaccharide structures may represent an early event in the complex pathogenesis of calcification in the CRST syndrome.

Actin Cytoskeleton↗
PubMed1991

Congenital hypothyroidism and pericardial effusion.

A group of infants, affected by congenital hypothyroidism diagnosed through the neonatal screening program, was investigated with echocardiography to detect the presence of pericardial effusion. We studied the relationship between the effusion and the etiology of hypothyroidism, established through thyroid scintiscanning. Our data show a high prevalence of effusion in hypothyroid patients, without other clinical signs of cardiac involvement as well as a relationship between the etiology of hypothyroidism and the presence of effusion. This seems to be much more frequent in those forms which can imply a more severe hormonal defect, particularly during fetal life (agenesis/dyshormonogenesis). Furthermore, the high prevalence of pericardial effusion suggests to start the L-T4 replacement therapy with lower dosages as commonly advised, in order to avoid a cardiac involvement.

Congenital Hypothyroidism↗
PubMed1991

Comparison between computed tomography and magnetic resonance imaging in the postoperative evaluation of acromegalic patients.

Twelve acromegalic patients who underwent transphenoidal resection of a GH-secreting pituitary adenoma were evaluated postoperatively by Computed Tomography (CT) and Magnetic Resonance (MR). CT and MR findings were compared with surgical and clinical results. MR was more accurate than CT in delineating postoperative abnormalities of the infundibulum, diaphragma sellae and optic chiasm. In three cases MR differentiated packing materials from adenomatous tissue. In cases with biochemical evidence of residual or recurrent tumor, MR clearly demonstrated intra- or extrasellar adenomatous tissue and the spatial relationship between the soft tissue mass and the cavernous sinuses. CT was superior to MR only in demonstrating sellar floor disruption. MR imaging detected the anatomical causes of clinical abnormalities in almost all acromegalic patients with incomplete recovery after surgery. On the basis of MR results it is possible to plan additional surgery, radiation therapy or medical treatment. MR may be the radiological procedure of choice for both surgical treatment planning and postoperative follow-up.

Acromegaly↗
PubMed1990

[Amiodarone-induced pigmentation. A histological, ultrastructural study and review of the literature].

Amiodarone is an iodinated cardiac antiarrhythmic drug that causes a slate- gray discoloration of sun-exposed skin. Histopathologically, biopsy specimens of two patients affected by amiodarone pigmentations reveal yellow-brown granules in the reticular dermis, both in the cytoplasm of macrophages and between the collagen bundles. The histochemical stainings of the granules suggest that a lipofuscin pigment rather than melanin is present in the granules. Electron microscopy displays distinctive intracytoplasmic inclusions in many dermal cell types. Six morphologic types can be seen: 1) electron-lucent, membrane bound granules, 2) granules with electron dense nucleus, 3) lamellar "myelin-like" granules, 4) granules with a combination of electron-dense and electron-lucent areas, 5) electron-dense membrane-bound granules, 6) electron-dense no-membrane granules. The different dimensions, structure and shape are related to the structural and aggregational phases of the granules. In particular their pathogenesis may be related to the action of the drug on cell membranes with thesaurismosis, local metabolic damage, accumulation of the drug in the lysosomes and acceleration of the physiological ageing cell process.

Aged↗
PubMed1987

Results of combined surgical and medical therapy in patients with prolactin-secreting pituitary macroadenomas.

To assess the long term effectiveness of combined sequential surgical and medical therapy in the management of prolactin-secreting pituitary macroadenomas, we followed 21 patients for 46 +/- 6 months (mean +/- SE) after diagnosis (range, 12 to 96 months). All patients underwent operation. Six were also treated with bromocriptine, 7.5 mg/day immediately after operation. A group of 15 patients with tumor sizes similar to those of the first group was followed without medical therapy until signs of regrowth of the neoplasia were evident. No patient of the combined therapy group experienced a recurrence of the disease. On the other hand, only 2 patients of the second group were recurrence-free at the end of follow-up. In the other 13 cases, adjunctive therapy had to be established for clinical and radiological evidence of tumor recurrence 26 +/- 7 months after operation. We conclude that combined sequential surgical and medical therapy may be useful in the management of macroprolactinomas. Our hypothesis must be confirmed by studies that compare patients treated with operation plus bromocriptine with patients treated with bromocriptine alone.

Adenoma↗