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Biomedical subjects

L M Cavallo

Publications and source records attributed to L M Cavallo.

18 recordsLinked to original sources
PubMed2005

Microsurgical repair of the facial nerve.

OBJECTIVE: To report a series of 18 patients who underwent microsurgical repair of the facial nerve using different techniques and to discuss the indications and results of facial reinnervation procedures. METHODS: Eighteen patients with post-surgical facial palsy underwent facial reinnervation using different techniques.'These included classic hypoglossal-facial anastomosis in 13 cases, one-stage hemihypoglossal-intratemporal facial nerve anastomosis and translabyrinthine removal of residual intra-canalar acoustic schwannoma in 3, hemihypoglossal-facial nerve anastomosis in one, and neurotization of facial muscles through a nerve graft in one. RESULTS: The facial muscle function improved in all patients, up to grade III in 7 cases (39 %), grade IV in 9 (50 %) and grade V in 2 (11 %). The tongue atrophy was minimal in 70.5 %, moderate in 17.5 % and severe in 12 %. The outcome was better in younger patients (less than 40 years of age) and in those with a lesser grade of preoperative facial impairment. CONCLUSIONS: The classic hypoglossal-facial anastomosis is the technique of choice in most cases. The use of the intratemporal facial nerve is indicated when removal of an intra-canalar residual schwannoma must also be performed. The neurotization of the facial muscles through a nerve graft may be used when there is no distal trunk of the facial nerve available for the anastomosis.

Adult↗
PubMed2004

Expression and function of somatostatin receptor subtype 1 in human growth hormone secreting pituitary tumors deriving from patients partially responsive or resistant to long-term treatment with somatostatin analogs.

The role of somatostatin (SS) receptor subtype 1 (SSTR(1)) in mediating the inhibitory effect of SS on growth hormone (GH) secreting pituitary tumors has been recently demonstrated. In the present study, we evaluated the effect of the selective SSTR(1) agonist BIM-23745 on in vitro GH secretion in GH-secreting pituitary tumor cells, deriving from patients resistant or partially responsive to octreotide long-acting release (octreotide-LAR) or lanreotide therapy in vivo and expressing SSTR(1) mRNA. In addition, the inhibiting effect of BIM-23745 on the GH secretion was compared with that of octreotide. Our data demonstrate that (1) SSTR(1) receptor was present in 56.25% (9/16) of the GH-secreting adenomas examined; (2) in all GH-secreting pituitary tumors that expressed SSTR(1), BIM-23745 significantly inhibited GH secretion in vitro, and (3) when SSTR(1) subtype was present in tumors from patients resistant to octreotide-LAR or lanreotide therapy, BIM-23745 was able to inhibit the in vitro GH secretion. In conclusion, the results of the current study suggest that SS analogs selective for the SSTR(1) may represent a further useful approach for the treatment of acromegaly in patients resistant or partially responsive to octreotide-LAR or lanreotide treatment in vivo.

Acromegaly↗
PubMed2004

Hemorrhagic vascular complications of endoscopic transsphenoidal surgery.

Two hundred and fifty consecutive patients operated on by an endoscopic endonasal transsphenoidal approach were retrospectively analyzed in order to evaluate hemorrhagic vascular complications occurring during or after the surgical procedure and their appropriate management. Vascular complications of endoscopic transsphenoidal surgery are identical to those of a microsurgical transsphenoidal approach. Damage to the sphenopalatine artery and to the internal carotid artery (ICA), which are the most frequent vascular troubles, may require technical tricks because of some aspects connected to the approach itself and of the physical properties of the endoscope. Furthermore, the progress in interventional neuroradiology in the last decades offers new solutions in respect to the past, where the use of the surgical microscope was already a tremendous progress. The anatomic substrate of each complication is discussed, along with the peculiar surgical details related to it.

Carotid Artery, Internal↗
PubMed2004

Endoscopic endonasal transsphenoidal removal of an intra-suprasellar schwannoma mimicking a pituitary adenoma.

Intracranial schwannomas, accounting for 8 to 10 % of all primary brain neoplasms, are relatively frequent intracranial tumors, but a "pure" intrasellar localization is exceptional. We report the case of an intra-suprasellar schwannoma mimicking a non-functioning pituitary macroadenoma both radiographically and clinically. A 73-year-old man presented with an episode of lipothymia followed by episodes of mental confusion. The neurological investigations revealed a bitemporal hemianopia and a hypopituitaric status. The neuroradiological investigations showed an intra-suprasellar mass resembling a pituitary adenoma. The patient underwent surgery performed by means of an endoscopic endonasal transsphenoidal approach, with a subtotal excision of the tumor. The histopathological studies revealed a cellular schwannoma. The review of the literature disclosed another 8 cases of intrasellar schwannomas. The possibility of an intrasellar schwannoma has to be considered in the differential diagnoses of neoplastic and non-neoplastic lesions of the sellar area.

Adenoma↗
PubMed2003

Dysembryogenetic spinal tumours in adults without dysraphism.

The authors report 15 patients with spinal intradural dysembryogenetic tumours with clinical onset in adult age in the absence of clinical and radiological signs of dysraphism. The series includes seven lipomas, four epidermoid cysts, three dermoid cysts and one teratoma. The tumour site was the thoracic region in three cases, the lumbar cord and conus in six, the cauda equina in four and the filum terminale in two. Among 14 patients operated upon, the surgical removal was complete in eight cases, subtotal in two and partial in four. Recurrence was noticed only in one subtotally resected thoracic epidermoid cyst. Magnetic resonance imaging allows a precise diagnosis of these lesions, mainly of small lipomas and dermoids of the conus and filum, where a tethered conus is responsible for clinical symptoms. Dysembryogenetic spinal rumours that become symptomatic in adult age may require surgical treatment. Reduction of the mass and release of any associated tethered neural elements are the goal of surgery for spinal lipomas, whereas epidermoid and dermoid cysts require a more radical treatment. However, even partial resections to avoid neural damage result in a good clinical outcome and very low risk of recurrence.

Adult↗
PubMed2003

Remifentanil for intraoperative analgesia during the endoscopic surgical treatment of pituitary lesions.

AIM: The authors have evaluated remifentanil for intraoperative analgesia in endonasal endoscopic surgery for pituitary lesions. METHODS EXPERIMENTAL DESIGN: a perspective, randomized and comparative study between remifentanil and fentanyl for intraoperative analgesia was performed in an operating room of the neurosurgical department at University. Sixty patients of both sexes were studied and randomly divided into 2 groups. Patients were premedicated with fentanyl 0.15 microg.kg(-1) and atropine 0.01 microg.kg(-1) (group F) or with atro-pine and remifentanil 0.25 microg.kg(-1) min-1 (group R); induction was with propofol 2.0 microg.kg(-1) and maintenance with titrated infusion of propofol and for intraoperative analgesia, fentanyl as bolus injection of 1.0-1.5 microg.kg(-1) (group F) or a titrated infusion of remifentanil (group R). The following parameters were studied: MAP, HR, bleeding, awakening times, adverse effects and VAS. RESULTS: Much more stable hemodynamic parameters during surgery in patients treated with remifentanil; labetalol was administered in 10% of patients in group F; no significant differences as regards the adverse effects and VAS. Faster awakening time was obtained in the remifentanil group as compared with the fentanyl group. CONCLUSIONS: Remifentanil analgesia (mean dose of 0.37 microg.kg(-1).min-1) in patients undergoing endonasal endoscopic surgery of the sellar region provides a more efficacious cardiocirculatory control with reduced bleeding and faster psychosensorial recovery.

Adult↗
PubMed2002

Very delayed hyponatremia after surgery and radiotherapy for a pituitary macroadenoma.

Severe hyponatremia (118 mmol/l) with natriuresis, consistent with cerebral salt wasting syndrome (CSWS), occurred 38 days after transsphenoidal surgery in a 59-year-old woman affected by a pituitary non-functioning macroadenoma. From the 35th day after surgery, she showed progressive polyuria, hypotension and hyponatremia associated with natriuresis, decreased plasma and increased urinary osmolality. The clinical examination revealed signs of dehydration and gradual decline in the level of consciousness. The anterior pituitary function was normal due to appropriate replacement of thyroid and adrenal axis. The patient was treated with saline administration until normal natremia and water balance were restored and neurological symptoms had completely disappeared. This case focuses on the unusually prolonged time of development of post-surgery hyponatremia, despite delayed symptomatic hyponatremia being reported to commonly occur 7 days after transsphenoidal surgery. Therefore, we would advise not to limit the periodic follow-up of the hydroelectrolytic balance to the first two weeks after surgery, but to prolong it until after discharge from hospital. In fact, an early diagnosis is of great importance to prevent permanent neurological damage or death. Since CSWS and syndrome of inappropriate secretion of ADH, the two disorders alternatively imputed to generate post-surgical hyponatremia, are characterized by different pathogenic mechanisms and require opposing therapeutic approaches, the occurrence of extracellular volume dilution or of increased sodium renal loss should be carefully investigated. The evidences in favor of CSWS, the possible mechanisms behind the syndrome and diagnosis and management of patients with post-transsphenoidal surgery CSWS are discussed.

Adenoma↗
PubMed2002

Endoscopic endonasal transsphenoidal approach: outcome analysis of 100 consecutive procedures.

The endoscopic endonasal transsphenoidal approach has been proposed in the past decade as a minimally invasive surgical technique for the removal of pituitary tumors. From January 1997 to November 1999, 100 consecutive patients with pituitary tumors underwent endoscopic endonasal surgery, according to Jho's technique. We employed 0 degrees, 30 degrees, 45 degrees, and 70 degrees rigid endoscopes, 18 - 30 cm in length, 4 mm in diameter with an outer sleeve for irrigation and secured to a holder. Among the 87 pituitary adenomas, tumor removal was total in 51, subtotal (> 80 %) in 20 and partial in 16 cases. Four craniopharyngiomas were totally removed and an intra-suprasellar arachnoid cyst was emptied; a biopsy was performed in the two patients with a clivus chordoma. The two cases of sphenoid sinusitis were cured by surgery, the three patients with spontaneous CSF rhinorrhea were successfully treated and the residual nasal meningocele was removed. The endoscopic endonasal transsphenoidal approach appeared to be less traumatic than the traditional microsurgical approach, was very effective, and was characterized by a reduced number of complications. However, the relatively small series together with the short follow-up do not allow us to draw definitive conclusions. The post-operative reduction in hospital stay (two days in 40 of 100), significantly reduced the cost of patient's management.

Adenoma↗
PubMed2001

Easy sellar reconstruction in endoscopic endonasal transsphenoidal surgery with polyester-silicone dural substitute and fibrin glue: technical note.

OBJECTIVE: To describe a simple method of sellar reconstruction after endoscopic endonasal transsphenoidal surgery that will allow rapid watertight closure of the sellar floor. METHODS: A bent sheet of a polyester-silicone dural substitute, fashioned for this purpose with scissors, is introduced into the sella after removal of the lesion. Because of the consistency of the sheet, it opens spontaneously and becomes stuck. Autologous fat tissue or gelatin foam is positioned thereafter, followed by another layer of the dural substitute; a film of fibrin glue completes the sealing. RESULTS: Fifteen patients underwent this method and no postoperative cerebrospinal leak or other complication was experienced. CONCLUSION: This easy method of sellar reconstruction represents an effective and fast possibility to perform the final step of the endoscopic transsphenoidal procedure, which otherwise may cause maneuverability problems in the limited space of one nostril.

Dura Mater↗
PubMed2001

Sella repair.

Explore the source record for details and available documents.

Adenoma↗
PubMed2000

The role of the endoscopic transsphenoidal approach in pediatric neurosurgery.

The endoscopic endonasal transsphenoidal approach to the sellar region for the removal of pituitary adenomas and of other neoplasms in the same area has proved its reliability and effectiveness for the very wide vision it offers, coupled with minimal surgical trauma. Indications and advantages of such a technique are reported, focused on the treatment of lesions of the sellar and parasellar environment in pediatric age-group patients, and based on a consecutive series of 100 patients, 3 of them adolescents, treated during the last 3 years.

Adenoma↗
PubMed2000

RAS1 regulates filamentation, mating and growth at high temperature of Cryptococcus neoformans.

Cryptococcus neoformans is a basidiomycete yeast and opportunistic human pathogen of increasing clinical importance due to the increasing population of immunocompromised patients. To further investigate signal transduction cascades regulating fungal pathogenesis, we have identified the gene encoding a RAS homologue in this organism. The RAS1 gene was disrupted by transformation and homologous recombination. The resulting ras1 mutant strain was viable, but failed to grow at 37 degrees C, and exhibited significant defects in mating and agar adherence. The ras1 mutant strain was also avirulent in an animal model of cryptococcal meningitis. Reintroduction of the wild-type RAS1 gene complemented these ras1 mutant phenotypes and restored virulence in animals. A dominantly active RAS1 mutant allele, RAS1Q67L, induced a differentiation phenotype known as haploid fruiting, which involves filamentation, agar invasion and sporulation in response to nitrogen deprivation. The ras1 mutant mating defect was suppressed by overexpression of MAP kinase signalling elements and partially suppressed by exogenous cAMP. Additionally, cAMP also suppressed the agar adherence defect of the ras1 mutant. However, the ability of the ras1 mutant strain to grow at elevated temperature was not restored by cAMP or MAP kinase overexpression. Our findings support a model in which RAS1 signals in C. neoformans through cAMP-dependent, MAP kinase, and RAS-specific signalling cascades to regulate mating and filamentation, as well as growth at high temperature which is necessary for maintenance of infection.

Animals↗
PubMed2000

Endoscopic endonasal transsphenoidal surgery in recurrent and residual pituitary adenomas: technical note.

Despite a good cure rate after surgery, the recurrence rate in pituitary adenomas is globally high. The decision making in such cases can be problematic for the nature of the lesion, for the anatomic structures involved, for the different pharmacological, surgical, radiotherapeutic and radiosurgical options nowadays available. In the perspective of an improvement and refinement of the surgical procedure an endoscopic endonasal transsphenoidal approach to the pituitary was recently adopted in the Neurosurgical Department of the University of Naples. Its minimal invasiveness and its wider and direct anatomic control of the operative field has allowed a faster, greater and safer potential of tumour excision, with respect of the sphenoid, sellar and parasellar structures. The authors have examined the advantages provided by this technique in 12 patients with recurrent pituitary adenomas and in 2 craniopharyngiomas already treated via a transnasal transsphenoidal approach (TTA), where the anatomy of surgical field had been distorted by the first operation or the radiation therapy. They conclude that the endoscopic transsphenoidal re-operation might be considered the procedure of choice in case of recurrences and its easiness in such conditions could favour its larger use, before other more aggressive therapeutic solutions.

Adenoma↗
PubMed1999

The STE12alpha homolog is required for haploid filamentation but largely dispensable for mating and virulence in Cryptococcus neoformans.

Cryptococcus neoformans is a fungal pathogen that causes meningitis in immunocompromised hosts. The organism has a known sexual cycle, and strains of the MATalpha mating type are more virulent than isogenic MATa strains in mice, and they are more common in the environment and infected hosts. A C. neoformans homolog of the STE12 transcription factor that regulates mating, filamentation, and virulence in Saccharomyces cerevisiae and Candida albicans was identified previously, found to be encoded by a novel region of the MATalpha mating type locus, and shown to enhance filamentous growth when overexpressed. We have disrupted the C. neoformans STE12 gene in a pathogenic serotype A isolate. ste12 mutant strains exhibit a severe defect in filamentation and sporulation (haploid fruiting) in response to nitrogen starvation. In contrast, ste12 mutant strains have only modest mating defects and are fully virulent in two animal models compared to the STE12 wild-type strain. In genetic epistasis experiments, STE12 functions in a MAP kinase cascade to regulate fruiting, but not mating. Thus, the C. neoformans STE12alpha transcription factor homolog plays a specialized function in haploid fruiting, but it is dispensable or redundant for mating and virulence. The association of the MATalpha locus with virulence may involve additional genes, and other transcription factors that regulate mating and virulence remain to be identified.

Amino Acid Sequence↗
PubMed1999

Rapamycin antifungal action is mediated via conserved complexes with FKBP12 and TOR kinase homologs in Cryptococcus neoformans.

Cryptococcus neoformans is a fungal pathogen that causes meningitis in patients immunocompromised by AIDS, chemotherapy, organ transplantation, or high-dose steroids. Current antifungal drug therapies are limited and suffer from toxic side effects and drug resistance. Here, we defined the targets and mechanisms of antifungal action of the immunosuppressant rapamycin in C. neoformans. In the yeast Saccharomyces cerevisiae and in T cells, rapamycin forms complexes with the FKBP12 prolyl isomerase that block cell cycle progression by inhibiting the TOR kinases. We identified the gene encoding a C. neoformans TOR1 homolog. Using a novel two-hybrid screen for rapamycin-dependent TOR-binding proteins, we identified the C. neoformans FKBP12 homolog, encoded by the FRR1 gene. Disruption of the FKBP12 gene conferred rapamycin and FK506 resistance but had no effect on growth, differentiation, or virulence of C. neoformans. Two spontaneous mutations that confer rapamycin resistance alter conserved residues on TOR1 or FKBP12 that are required for FKBP12-rapamycin-TOR1 interactions or FKBP12 stability. Two other spontaneous mutations result from insertion of novel DNA sequences into the FKBP12 gene. Our observations reveal that the antifungal activities of rapamycin and FK506 are mediated via FKBP12 and TOR homologs and that a high proportion of spontaneous mutants in C. neoformans result from insertion of novel DNA sequences, and they suggest that nonimmunosuppressive rapamycin analogs have potential as antifungal agents.

Amino Acid Sequence↗