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Biomedical subjects

G Maira

Publications and source records attributed to G Maira.

At least 73 records · Page 4Linked to original sources
PubMed1985

Peripheral nerve autografts to the injured spinal cord of the rat: an experimental model for the study of spinal cord regeneration.

Regenerated central axons have been shown experimentally to penetrate in peripheral nerve segments transplanted into the spinal cord (SC). However, if the nerves are transplanted between the stumps of the transected SC regeneration is impaired by local cavitation and scarring. Our experiment was designed to study whether nerve grafts bridging a severe transverse SC lesion might provide to central regenerating axons a pathway to by-pass the lesion. To this purpose, 2 segments of autologous peripheral nerves were inserted through small dural openings into dorsal longitudinal myelotomies rostral and caudal to a transverse SC lesion in rats. Eighteen weeks after transplantation a large number of well myelinated fibres filled the grafted nerves. Only a few of these fibres, however, could be followed into the SC; they were located in the outer layers of the dorsal white matter. The problems regarding the origin and destination of these fibres are discussed.

Animals↗
PubMed1985

Evaluation of dopaminergic tone in hyperprolactinemia. III. Thyroid-stimulating hormone response to metoclopramide in differential diagnosis and postoperative follow-up of prolactinoma patients.

Recently, it has been shown that patients with a PRL-secreting pituitary adenoma have a greater thyroid stimulating hormone (TSH) release after dopamine (DA)-receptor blockade than normal subjects. We have compared the TSH and PRL responses to metoclopramide (MCP) in normal and postpartum lactating women with those in 28 patients with hyperprolactinemia of different origin. Patients with a PRL-secreting pituitary adenoma were also tested after transsphenoidal removal of the tumor in order to establish the prognostic value of this test in such patients. Following MCP administration, percent increases in plasma PRL levels were greater in normal female subjects than postpartum lactating women. Plasma TSH levels did not increase in postpartum women and had a modest increment in normal subjects. In patients with hypothalamic tumors and empty sella syndrome plasma PRL and TSH levels showed modest or no increases after MCP administration. In ten patients harboring a microprolactinoma, plasma TSH levels showed an exaggerated increment after DA-receptor blockade. Postoperatively, despite normal or borderline PRL levels in the immediate postoperative period, a TSH response to MCP was present (in five patients one to two weeks after the operation, and in five patients one to three years after the operation), suggesting an increased DA activity even in the absence of hyperprolactinemia. In conclusion, the TSH test can easily detect increased DA-activity in patients with a microprolactinoma both preoperatively and postoperatively. It is possible that some patients with increased DA-activity in presence of normal PRL levels and normal PRL responsiveness to stimulation will experience a recurrence of hyperprolactinemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1985

Prolactin dynamics in patients with non-secretin tumours of the hypothalamic-pituitary region.

Twenty-four patients with non-secreting tumours of the hypothalamic-pituitary region, diagnosed by radiographic procedures and confirmed at surgery, were examined before and after the surgical treatment to establish a correlation between Prl responsiveness to dynamic tests and the location of pathological tissue. Three groups of patients were identified. In 10 patients with an intrasellar tumour (group I), Prl had a positive response to TRH, metoclopramide (MCP), and nomifensine (NOM), both pre- and postoperatively. In 4 patients with tumours located entirely in the hypothalamus (group II), Prl responded to TRH, but remained unresponsive to MCP and NOM. Only a partial normalization of the Prl responses was obtained after surgery. Finally, 10 patients had an intra- and extrasellar tumour (group III). In 8 of them Prl responded to TRH, but the increment was lesser than that observed in hypothalmic tumours. Prl did not respond to MCP and NOM. After surgery, Prl responsiveness reappeared in some patients (6 after TRH, 4 after MCP, 3 after NOM). In 2 patients with extensive pituitary damage, Prl did not respond to all dynamic tests pre- or postoperatively. In conclusion, Prl dynamic tests are a reliable tool for studying the altered control of Prl secretion in these patients, since plasma Prl stems from only normal lactotropes surrounding the tumoural tissue. The location of the tumour has a key role in influencing the pattern of Prl response to direct and indirect dynamic tests.

Adenoma↗
PubMed1984

Immunohistochemical detection of folliculo-stellate cells in human pituitary adenomas.

In the light of recent findings concerning the presence of S-100 antigen in folliculo-stellate cells of the rat adenohypophysis, we investigated the possible presence of S-100-labelled cells in both the normal human adenohypophysis and in pituitary adenomas. Immunostaining enabled us to detect, with both light and electron microscopy, the presence of S-100-labelled folliculo-stellate cells in a significant number of pituitary adenomas, mostly growth-hormone secreting, and, as expected, in the normal human adenohypophysis.

Adenoma↗
PubMed1984

Multicentric experience on the acute effect of nomifensine in hyperprolactinemic women.

The inhibitory effect of nomifensine ( Nom ; 200 mg orally) on prolactin (PRL) secretion was studied in 15 subjects with puerperal hyperprolactinemia and in 59 pathologic hyperprolactinemic women. The latter were grouped as follows: i) patients with surgically proven PRL secretory pituitary adenomas (proven tumors; 27 cases); ii) patients presenting radiological signs of sella indicative of a pituitary tumor (presumptive tumors; 10 cases); iii) subjects with non-drug induced hyperprolactinemia (hyperprolactinemia of uncertain etiology; 22 cases). A mean PRL fall of 30% or more of baseline hormone levels in samples collected within the 120-240 min post-treatment interval was adopted to define responsiveness to Nom . In 24 out of 27 subjects with proven tumors and in 9 out of 10 subjects with presumptive tumors Nom did not induce significant variations in PRL secretion. In only 11% of the patients with surgery-confirmed or highly suspected tumors a hormone decrease greater than 30% was observed. In addition, 13 subjects with hyperprolactinemia of uncertain etiology did not respond to Nom administration. In 5 of these, additional data suggesting the existence of an adenoma were collected. Finally, 3 out of 9 Nom -responder patients presented either a polycystic ovary syndrome or transitory hyperprolactinemia. The finding that hyperprolactinemic women, who did not show clinical or radiological signs of a tumor and patients with highly presumptive or proven pituitary tumors may present comparable responses to Nom , suggests that this pattern may be indicative of an early manifestation of a PRL-secreting adenoma which has yet to evolve. The follow-up of Nom -non-responder hyperprolactinemic subjects who did not show clinical signs of harboring a tumor, is therefore advisable.

Adolescent↗
PubMed1984

Relationships between intracranial pressure and diurnal prolactin secretion in primary empty sella.

The role of the intracranial pressure (ICP) in the development and/or maintenance of the primary empty sella has been evaluated by recording the ICP during sleeping and waking periods in 11 women who had this syndrome. Concomitantly, plasma PRL levels, measured at 2-hour intervals during a 24-hour period, were compared with the changes in ICP. Daily PRL variations were also measured in 5 normally cycling and 5 postmenopausal women. ICP was abnormally increased in 8 patients with PES. In 3 of them, increased values were recorded during waking and sleeping periods, while in 5 subjects abnormal values were observed only during sleep. In the remaining 3 patients the ICP was normal in all conditions tested. 8 patients with elevated ICP presented an absent or blunted nocturnal PRL increase. In 3 patients with normal ICP, the circadian periodicity of PRL was preserved. The normalization of ICP obtained in 4 patients by a surgical shunting procedure was accompanied by the return to normal of the circadian PRL periodicity. Our observations demonstrate that the finding of a normal ICP during wakefulness is not sufficient to rule out an actual increase in ICP, since a rise in the CRF pressure can occur during sleep. Our data also demonstrated a correlation between an abnormal rise in ICP and an absent or blunted nocturnal increment in PRL secretion.

Adult↗
PubMed1984

Postoperative evaluation of dopaminergic tone in prolactinoma patients. II. Plasma thyrotropin response to metoclopramide.

In 24 patients who had a PRL-secreting pituitary adenoma, diagnosed by pituitary dynamic function tests and CT scan, and confirmed at surgery, the TSH response to a dopamine (DA)-antagonist drug, metoclopramide (MCP), was studied pre- and postoperatively to elucidate whether altered DA tone was present and related to hyperprolactinemia. Preoperatively, a TSH response to MCP occurred in 18 patients. Plasma TSH levels did not increase after MCP in 5 patients who had a macroprolactinoma and in 1 patient with a microprolactinoma located just beneath the diaphragm of the sella turcica. Postoperatively, in all patients who had a prolonged clinical remission and normalization of PRL dynamic tests TSH did not respond to MCP (9 of 24 patients). In 4 patients who had normal or borderline PRL levels in the immediate postoperative period, the TSH response to MCP disappeared, but became evident later together with progressive elevation of PRL levels. TSH increases after MCP occurred in all patients who had abnormal PRL levels after surgery, except in 2 patients with a macroprolactinoma infiltrating the neighboring structures. In conclusion, these results confirm the existence of increased DA tone in patients with a prolactinoma. However, the presence of an increased TSH response to DA antagonist drugs could be masked in patients who had large tumors or tumors located just beneath the sellar diaphragm. The TSH test after MCP administration can readily detect increased DA tone in the postoperative period even when PRL levels remain slightly elevated or borderline.

Adenoma↗
PubMed1984

Multiple intracranial metastases of malignant melanoma with long-term survival. Case report.

The authors present a case of multiple brain metastases and an extracranial secondary localization from malignant melanoma. The patient was operated on three times for the intracranial masses and had a 49-month survival with a good quality of life after the first of the three operations. She lived a total of 80 months from the time of diffusion of the primary tumor. The course of malignant melanoma is unpredictable, and long-term survival can be achieved in some cases, even in the presence of multiple brain metastases.

Adult↗
PubMed1982

Dopaminergic mechanisms regulating prolactin secretion in patients with prolactin-secreting pituitary adenoma. Long-term studies after selective transsphenoidal surgery.

Twenty-seven female patients with prolactin-secreting pituitary microadenoma, were studied at different intervals following selective transsphenoidal removal of the tumor. Postoperatively, all patients had normal prolactin (PRL) levels and regular menstrual cycles were restored. Sixteen of 27 patients showed positive responses to TRH and metoclopramide (MCP) within 1 mo after surgery. On the contrary, 9 patients showed evaluation of these patients demonstrated that normal neuroendocrine relationships were restored after several months since positive PRL responses to TRH and MCP could be elicited in such patients. The remaining 2 patients who showed basal PRL levels in the upper range of normal, exhibited negative responses to TRH and MCP. These patients had progressively to TRH and MCP exhibited 10-20 mo after surgery a normal decrease in PRL levels following administration of carbidopa plus L-Dopa. Negative responses to carbidopa plus L-Dopa were instead obtained in 6 postoperative patients with elevated PRL levels and negative responses to TRH and MCP. These results suggest that: 1) Hyperprolactinemia induced by "autonomous" pituitary adenomas increases hypothaLamic dopamine (DA) secretion, which in turn inhibits PRL secretion by nonadenomatous lactotropes. 2) Total selective removal of the microadenoma acutely decreases PRL concentration, but a functional inhibition of the normal lactotrope can persist for a period of few months following surgery in a certain number of patients. 3) Prolonged reduction of PRL concentration is accompanied to a normal DA tone with reestablishment of normal neuroendocrine relationships.

Adenoma↗
PubMed1982

Hyperprolactinemia as the first symptom of craniopharyngioma.

The endocrinological alterations related to craniopharyngiomas are usually described as panhypopituitarism. The growth failure in the prepuberal child and/or the puberal retard are the clinical symptoms usually related to it. Nevertheless, for the peculiar diencephalic control of the prolactin (PRL) pituitary secretion, different endocrinological pictures can be observed, related to the different degree of pituitary-hypothalamic compression from the craniopharyngioma. For these reasons a dynamic PRL pre- and postoperative evaluation has been performed in 4 patients operated on for craniopharyngioma. A correlation has been made between hormonal picture, size and location of the tumor, and surgical results. The value of these data in performing an early diagnosis in children with craniopharyngioma is discussed.

Adolescent↗
PubMed1981

Sodium nitroprusside and intracranial pressure.

The effects of sodium nitroprusside on intracranial pressure were studied in 10 patients, candidates for surgical treatment, prior to anaesthesia. Blood pressure was lowered to at least 50% of its initial value. In all cases, at the beginning of nitroprusside infusion, both the mean and the pulse intracranial pressures increased (mean increase: 83.2% of the initial value). At a certain moment, however, while the blood pressure continued to fall, the mean intracranial pressure did not increase any more; on the contrary, it decreased. On the other hand, in many cases, the pulse intracranial pressure continued to increase. No neurological or EEG changes were observed. The possible changes of cerebral circulation and CSF dynamics underlying the phenomena observed are discussed.

Adult↗