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Biomedical subjects

A Spada

Publications and source records attributed to A Spada.

At least 73 records · Page 4Linked to original sources
PubMed1999

Restenosis following angioplasty in the swine coronary artery is inhibited by an orally active PDGF-receptor tyrosine kinase inhibitor, RPR101511A.

BACKGROUND: Platelet-derived growth factor (PDGF), a purported mediator of arterial response to injury, stimulates proliferation, chemotaxis, and matrix production by activation of its membrane receptor tyrosine kinase. Because these activities underlie restenosis, inhibition of the PDGF-receptor tyrosine kinase (PDGFr-TK) is postulated to decrease restenosis. METHODS AND RESULTS: RPR101511A is a novel compound which selectively and potently inhibits the cell-free and in situ PDGFr-TK and PDGFr-dependent proliferation and chemotaxis in vascular smooth muscle cells (VSMC). To evaluate the effect of RPR101511A (30 mg. kg-1. d-1 BID for 28 days following PTCA) on coronary restenosis, PTCA was performed in hypercholesterolemic minipigs whose left anterior descending (LAD) coronary artery had been injured by overdilation and denudation, yielding a previously existing lesion. Angiographically determined prePTCA minimal lumen diameters (MLD) were similar in vehicle and RPR101511A-treated pigs (1.98+/-0.09 versus 2.01+/-0.08 mm) and increased to the same extent in the 2 groups following successful PTCA (2.30+/-0.06 versus 2.52+/-0.13). At termination, there was an average 50% loss of gain in the vehicle-treated group but no loss of gain with RPR101511A (2.16+/-0. 05 versus 2.59+/-0.11, P<0.001). Morphometric analysis of the LAD showed that RPR101511A caused a significant decrease in total intimal/medial ratio (0.96+/-0.58 versus 0.67+/-0.09, P<0.05). CONCLUSIONS: RPR101511A, which acts by inhibition of the PDGFr-TK, completely prevented angiographic loss of gain following PTCA and significantly reduced histological intimal hyperplasia.

Administration, Oral↗
PubMed1999

Treatment of anal carcinoma in the elderly: feasibility and outcome of radical radiotherapy with or without concomitant chemotherapy.

BACKGROUND: For most cancers, information on treatment tolerance and results for elderly patients is quite limited. This study was conducted to investigate the feasibility and results of curative nonsurgical treatment of patients age 75 years or older with anal carcinoma. METHODS: From January 1976 through June 1996, invasive anal squamous cell carcinoma was diagnosed in 58 patients age > or = 75 years. Curative treatment was administered to 47 patients (81%), of whom 42 received radiotherapy (RT), either used alone (21) or associated with concomitant chemotherapy (CT). RT was administered in two sequences, the first in which a median dose of 39.6 gray (Gy) was delivered with megavoltage photon beams, followed (after a median interval of 43 days) by a boost with either brachytherapy or external beam (median dose, 20 Gy). CT started on Day 1 and generally consisted of 1 cycle of mitomycin C (MMC; median dose, 9.5 mg/m2) and a 96-hour infusion of 5-fluorouracil (5-FU; median dose, 600 mg/m2/day). The median follow-up for all patients was 48 months (range, 5-163 months). RESULTS: Of 40 patients (95%) who completed curative treatment, acute toxicity resulted in shortening of the planned first irradiation sequence in 2 patients (1 in each group) and an unplanned treatment break in 11 patients (4 in the RT group and 7 in the RT-CT group). Grade 2 and 3 acute reactions (RTOG) were observed in 43% and 54% of patients, respectively. Among all Grade 3 reactions, 32% occurred in the RT group and 68% in the RT-CT group. In patients receiving RT-CT, Grade 2-3 leukopenia was observed in 25% of patients, Grade 2-3 fatigue was observed in 58% of patients, and Grade 2 cardiac toxicity related to 5-FU occurred in 1 patient. At 5 years, the overall survival was 54% (49% and 59% for the RT and RT-CT groups, respectively, P = 0.28), and the actuarial local control rate was 78.5% (73% and 83% for the RT and RT-CT groups, respectively, P=0.36). Five patients presented with Grade 3-4 late complications, all of them in the RT-CT group. CONCLUSIONS: The current series confirms the feasibility of sphincter-conserving treatment for elderly patients who present with anal carcinoma. Rates of acute or late complications appeared similar to those observed in younger patients, and the oncologic results were at least as favorable as those commonly reported.

Aged↗
PubMed1999

Bioactivity and glycosylation of circulating prolactin in various physiological and pathological conditions.

Multiple posttranslational processes modify native PRL and result in the secretion of several PRL isoforms with different bioactivity. Since we observed that serum samples contain non-lactogenic substances able to interfere in Nb2 cell bioassay, in this study we extracted PRL molecules from sera of pregnant and non-pregnant normal adults, fetuses and patients with prolactinoma and evaluated the ability of partially purified PRL to stimulate Nb2 cell proliferation. The preliminary immunopurification of PRL samples, conferred good sensitivity and specificity to PRL biological assay. Whenever possible, bioactivity values were correlated with glycosylated-PRL levels (G-PRL), the major posttranslational modification known to reduce PRL bioactivity. The ratio of bioactive (B-) vs immunoreactive PRL (I-PRL) (B/I) in normal subjects was 0.9 +/- 0.1 (mean +/- SD), and not affected by TRH and sulpiride administration. PRL B/I ratio did not change during pregnancy, both in maternal (0.8 +/- 0.1) and fetal circulation (1.0 +/- 0.01). In patients with prolactinoma PRL B/I ratios (0.8 +/- 0.18) were in the normal range. However, in 2 women with microprolactinoma, with a clear discrepancy between high I-PRL levels and mild clinical features, a significantly reduced PRL B/I ratio was observed (0.51 +/- 0.08 and 0.52 +/- 0.1 respectively). Conversely, a woman with clear clinical features of hyperprolactinemia, but border-line elevated I-PRL levels had a PRL B/I ratio in the upper limit of normal range. No variation in G-PRL vs NG-PRL percentages was observed in all the cases studied. In conclusion, our data show that physiological and pathological conditions of hyperprolactinemia, including fetal life, are associated in the majority of cases, with the secretion of PRL molecules with unchanged mitogenic activity on Nb2 cells. Nb2 PRL bioassay may be an useful tool to explain the discrepancies between clinical features and immunoreactive PRL levels in some particular cases.

Adolescent↗
PubMed1999

Expression of calcium-sensing receptor and characterization of intracellular signaling in human pituitary adenomas.

Extracellular Ca(2+)-sensing receptor (CaSR) has been recently identified in rat and mouse pituitary and in AtT-20 cells. The aim of the study was to investigate the presence of CaSR in the human pituitary and its signaling pathway. Normal parathyroid biopsies, autoptic normal pituitaries, and seven nonfunctioning and six GH-secreting adenomas were studied. Southern blot analysis of the RT-PCR products from pituitary adenomas indicated that the PCR fragments obtained were products of specific amplification of CaSR messenger ribonucleic acid. Sequence analysis showed nucleotide identity of these products with the available human parathyroid CaSR. By immunoblotting analysis CaSR, was detected in normal and adenomatous pituitary tissues. In all tumors studied, extracellular Ca2+ (2.5 mmol/L) induced a significant increase in intracellular Ca2+, mainly due to Ca2+ mobilization (from 82.7+/-11 to 148+/-36 nmol/L; P < 0.001). Similar results were obtained with the CaSR activators gadolinium and neomycin. Moreover, CaSR activators significantly increased cAMP levels; this effect was not mimicked by other agents able to increase intracellular Ca2+, such as TRH. CaSR agonists did not increase resting GH secretion in any GH-secreting adenomas, but amplified the GH response to GHRH. In this study we first demonstrate CaSR expression in the human pituitary and provides evidence for an additional mechanism by which calcium might regulate pituitary cell function.

Adenoma↗
PubMed1998

G protein abnormalities in pituitary adenomas.

It has been demonstrated that the majority of secreting and nonsecreting adenomas is monoclonal in origin suggesting that these neoplasia arise from the replication of a single mutated cell, in which growth advantage results from either activation of protooncogenes or inactivation of antioncogenes. Although a large number of genes has been screened for mutations, only few genetic abnormalities have been found in pituitary tumors such as allelic deletion of chromosome 11q13 where the MEN-1 gene has been localised, and mutations in the gene encoding the alpha subunit of the stimulatory Gs and Gi2 protein. These mutations constitutively activate the alpha subunit of the Gs and Gi2 protein by inhibiting their intrinsic GTPase activity. Both Gs alpha and Gi2alpha can be considered products of protooncogenes (gsp and gip2, respectively) since gain of function mutations that activate mitogenic signals have been recognized in human tumors. Gsp oncogene is found in 30-40% of GH-secreting adenomas, in a low percentage of nonfunctioning and ACTH-secreting pituitary adenomas, in toxic thyroid adenomas and differentiated thyroid carcinomas. The same mutations, occurred early in embriogenesis, have been also identified in tissues from patients affected with the McCune Albright syndrome. These mutations result in an increased cAMP production and in the subsequent overactivation of specific pathways involved in both cell growth and specific programmes of cell differentiation. By consequence, the endocrine tumors expressing gsp oncogene retain differentiated functions. The gip2 oncogene has been identified in about 10% of nonfunctioning pituitary adenomas, in tumors of the ovary and the adrenal cortex. However, it remains to be established whether Gi proteins activate mitogenic signals in pituitary cells. Since Gi proteins are involved in mediating the effect of inhibitory neurohormones on intracellular effectors, it has been proposed that in pituitary tumors the low expression of these proteins, particularly Gi1-3alpha, may contribute to uncontrolled pituitary cells growth by preventing the transduction of inhibitory signals. While by in vitro mutagenesis it has been demonstrated that activated mutant of Gq alpha, G12alpha, G13alpha and Gz alpha are fully oncogenic, it remains to be proved whether or not these abnormalities might naturally occur in human tumors and, in particular, in pituitary adenomas.

Adenoma↗
PubMed1998

Serum FSH bioactivity and inhibin levels in patients with gonadotropin secreting and nonfunctioning pituitary adenomas.

It has been reported that serum FSH bioactivity and inhibin levels can be used as markers of the presence of true gonadotropin-secreting pituitary adenoma (Gn-oma). To verify this hypothesis, we have investigated the bioactivity of FSH and serum inhibin alpha-alpha and alpha-beta A levels in a series of patients with either Gn-oma or nonfunctioning pituitary adenoma (NFPA). Nine patients with Gn-oma (6 men and 3 women), 21 with NFPA (9 men and 12 women) and 30 normal subjects were included in the study. We studied FSH biological activity (FSH-B) by using Sertoli cell aromatase bioassay (SAB) and alpha-alpha and alpha-beta A inhibin levels by two noncompetitive immunometric assays (IEMA). In male patients with Gn-oma, serum immunoreactive FSH (FSH-I) and FSH-B levels ranged from 5.1 to 35.5 U/L and from 8.3 to 48 U/L, respectively, FSH B/I ratio being elevated in 2 (2.5 and 4.1; normal male range: 0.3-1.5), while female patients with Gn-oma had serum FSH-I and FSH-B levels ranging from 43.2 to 162 U/L and from 41.2 to 112.8 U/l, respectively, with a normal FSH B/I ratio. In male patients with NFPA, FSH-I and FSH-B levels ranged from 2.7 to 10.7 U/l and from 2.4 to 11.4 U/l while in females they ranged from 3.4 to 67.9 and from 4.6 to 60.8 U/l, respectively. FSH B/I ratio was elevated in 1 male (3.3) and normal in the remaining patients with NFPA. Serum alpha-alpha inhibin levels were normal or low in patients with Gn-oma and NFPA, while alpha-beta A inhibin concentrations were slightly elevated in 1 of 6 postmenopausal women (0.9; normal range < 0.7 U/ml). The present study confirms and extends previous reports indicating that male patients with Gn-oma may secrete FSH molecules with increased bioactivity. However, this abnormality was also observed in one male patient with NFPA. Moreover, the measurement of inhibin levels does not appear to be a reliable in vivo marker of pituitary tumors of gonadotroph origin, as it was normal or low in almost all patients with either Gn-oma or NFPA.

Adenoma↗
PubMed1998

Activating mutations of the Gs alpha gene are associated with low levels of Gs alpha protein in growth hormone-secreting tumors.

Evidence suggests the existence of a direct relationship between cellular Gs alpha content and activation of the adenylyl cyclase system. Data on Gs alpha levels in endocrine tumors that depend on cAMP for growth, particularly pituitary adenomas, are still limited. The levels of Gs alpha protein were evaluated in 11 GH-secreting adenomas with Gs alpha mutations (gsp+) and 15 without (gsp). Complementary DNAs from gsp+ tumors contained very low amounts of wild-type Gs alpha sequences, indicating a preponderance of the mutant Gs alpha transcripts in these tumors. Immunoblotting of Gs alpha protein showed that the two isoforms were present at high levels in all gsp-, but were undetectable or barely detectable in gsp+. The low Gs alpha content in gsp+ tumors was not due to a reduction in ribonucleic acid synthesis or stability, as Gs alpha messenger ribonucleic acid levels were similar in wild-type and mutant tissues. Treatment of gsp- cells with cholera toxin caused a marked reduction of Gs alpha levels. As in other cell systems cholera toxin increases Gs alpha degradation, our data are consistent with an accelerated removal of mutant Gs alpha. This may represent an additional mechanism of feedback response to the constitutive activation of cAMP signaling in pituitary tumors with mutations in the Gs alpha gene.

Adenoma↗
PubMed1998

Constitutively active Gs alpha is associated with an increased phosphodiesterase activity in human growth hormone-secreting adenomas.

Because phosphodiesterase (PDE) expression and activity are controlled by cAMP, we investigated whether activating mutations of Gs alpha gene that occur in human GH-secreting adenomas are associated with increased PDE activity. We studied 10 adenomas with wild-type Gs alpha (gsp-) and 8 with mutant Gs alpha (gsp+). Although, in the absence of PDE inhibitors, intracellular cAMP levels were similar in gsp+ e gsp- adenomas, the PDE blockade with 3-isobutyl-1-methylxanthine induced a marked increase in cAMP in all but one gsp+ adenoma (% increase: from 77 to 2900) and a slight rise in only 2 gsp-. Similar results were obtained with the PDE4 selective inhibitor 4-[3-(cyclopentyloxy)-4-methoxyphenyl)]-2-pyrrolidinone. In vitro GH release was significantly higher in gsp+ than in gsp- adenomas (315 +/- 158 vs. 82 +/- 53 micrograms/well; P < 0.01), and PDE blockade caused a further increase in 3 of 5 gsp+ adenomas but not in gsp- tumors. By direct measurement, PDE activity was about 7-fold higher in gsp+ than in gsp- adenomas (320 +/- 213 vs. 48 +/- 23 pmol/min.mg protein; P < 0.05) and was largely 4-[3-(cyclopentyloxy)-4-methoxyphenyl]-2-pyrrolidinone sensitive. This study first demonstrates that activating mutations of the Gs alpha gene that naturally occur in pituitary adenomas is associated with an increased PDE activity that might, at least partially, counteract the constitutive activation of the cAMP-dependent pathway.

1-Methyl-3-isobutylxanthine↗
PubMed1998

Growth hormone-releasing hexapeptide (GHRP-6) increases intracellular calcium concentrations in cultured cells from human pituitary adenomas of different types.

OBJECTIVE: The GH-releasing peptide GHRP-6, has been found to interact with specific receptors in somatotrophs, causing cytosolic Ca2+ ([Ca2+]i) rise and GH release. Moreover, this peptide has been demonstrated to stimulate the secretion of pituitary hormones other than GH, i.e. ACTH and prolactin, this effect being generally attributed to a central action. In this study we evaluated whether the pituitary action of this peptide is restricted to cell type of somatotroph lineage. METHODS: The effect opf GHRP-6 on [Ca2+]i was tested in cell preparations obtained from a series of human pituitary adenomas (9 GH-secreting adenomas, 7 nonfunctioning adenomas, 3 ACTH-secreting adenomas, 2 TSH-secreting adenomas and 1 prolactinoma) loaded with the Ca2+ indicator fura-2. RESULTS: GHRP-6, at concentrations higher than 1 nmol/l, significantly increased [Ca2+]i in all tumours, with the exception of the 3 ACTH-secreting adenomas in which the peptide was ineffective at any concentration tested (from 1 nmol/l to 1 micromol/l). By contrast, in all ACTH-secreting adenomas, both corticotrophin-releasing hormone and pituitary adenylate cyclase activating peptide caused a marked [Ca2+]i increase. In tumours responsive to GHRP-6, the peptide caused a typical biphasic [Ca2+]i rise due to Ca2+ mobilization from the intracellular stores and Ca2+ influx through voltage-dependent Ca2+ channels. CONCLUSIONS: These data indicate that almost all tumoral pituitary cell types are targets of GHRP-6 action, the only exception being corticotrophs.

Adenoma↗
PubMed1997

Immunodetection of glycoprotein hormone subunits in nonfunctioning and glycoprotein hormone-secreting pituitary adenomas.

While it is established that nonfunctioning pituitary adenomas (NFPA) produce a spectrum of glycoprotein hormones, the ability of glycoprotein hormone-secreting adenomas to synthesize hormones other than those in vivo hypersecreted has been poorly investigated so far. In this study the immunolocalization of the beta-subunits of LH, FSH, CG and TSH and the common alpha-subunit was investigated in 10 NFPA, 3 gonadotropin-secreting adenomas (Gn-omas, 1 LH-oma, 1 FSH-oma and 1 LH/FSH-oma) and 3 TSH-secreting adenomas (TSH-omas) using an immunohistochemical technique with specific antibodies to glycoprotein subunits. The percentage of positive cells was determined observing at least 5 photograph fields containing about 50 cells. Nine of the 10 NFPA were positive for FSH beta with a high percent of positive cells (> or =30%), 6 for LH beta and 5 for TSH beta with a lower number of labelled cells (from 5 to 30%). Of the 8 NFPA tested, 5 showed a marked positivity for CG beta. In Gn-omas, tumors were positive for the gonadotropin that was in vivo hypersecreted (10-60% positive cells) and negative for either TSH beta or CG beta. Similarly, in TSH-omas TSH beta was detected in a variable proportion of cells (10-30%) with no immunoreactivity for either LH beta or FSH beta or CG beta. This study indicates that the coexpression of FSH beta, LH beta, CG beta and TSH beta molecules is characteristic of NFPA since Gn-omas were negative for CG beta and TSH beta and TSH-omas were negative for FSH beta, LH beta and CG beta. Moreover, the biological events that make NFPA 'silent' glycoprotein hormone-secreting adenomas remain unclear since the positivity for gonadotropins and TSH showed by NFPA was similar to that observed in Gn-omas and TSH-omas, respectively.

Adenoma↗
PubMed1997

Paclitaxel as a radiosensitiser: a proposed schedule of administration based on in vitro data and pharmacokinetic calculations.

Paclitaxel is efficacious against many human cancers. Because it blocks cells at the radiosensitive G2-M interface, paclitaxel has been investigated as a radiosensitiser. The results have been equivocal and somewhat contradictory. It is impossible to obtain proper pharmacokinetic calculations, aimed at obtaining maximum cytotoxicity and/or radiosensitisation, without knowing (i) how long the drug must be in contact with the cells, (ii) how long the effect lasts after the drug is removed from the cellular environment, (iii) whether the drug acts as a radiosensitiser even when, like cis-platinum, it is added after the radiation and (iv) what the minimum quantity of drug in the cellular environment is required for both chemotoxicity and radiosensitisation. The present work addresses the above questions. Two radioresistant cell lines of human origin were used, A375 melanoma and S549 lung carcinoma, in a clonogenic assay where only colonies with 50 or more cells were counted. For the irradiation, 6 MV X-rays were used. Any G2-M block was quantified by cell cycle kinetics analysis. From the results, a simulation of pharmacokinetics was conducted to calculate the schedule of administration of paclitaxel most likely to achieve and maintain significant chemotoxocity and radiosensitisation. The minimum concentration of paclitaxel for measurable cytotoxicity was 3 nM for both cell lines, but the drug was more toxic to the A549 cells. The minimum concentration for measurable radiosensitisation was 3 nM for A375 and approximately 0.1 nM for A549, but whereas above 3 nM the radiosensitivity increased in A375, it decreased above 1 nM for A549. A minimum of 18 h incubation with the drug was necessary for measurable effects and the radiosensitising effects were lost soon after its removal. There was no radiosensitisation if paclitaxel was added after the radiation, and, at the minimum effective concentrations, it caused only a minor and transient G2-M block. The pharmacokinetic calculations predict that 15 mg/m2 paclitaxel given as a 1 h infusion 5 days/week for 3 weeks during the radiotherapy should achieve both cytotoxicity and radiosensitisation. The mechanism of radiosensitisation by paclitaxel at the concentrations suggested by our results does not appear to be via a G2-M block and is probably concentration dependent. The results imply that low-dose, daily infusions of paclitaxel for as long as possible during a course of radiotherapy are more likely to result in radiosensitisation and prolonged cytotoxicity than high-dose infusions given once a week.

Cell Cycle↗
PubMed1997

Multiple endocrine neoplasia type 1 in patients with recognized pituitary tumours of different types.

OBJECTIVE: We have investigated the prevalence of MEN 1 in patients with recognized pituitary adenomas. Since hyperparathyroidism is present in nearly 95-100% of patients with MEN 1 and frequently is the first condition to be identified, the study was limited to the identification of patients with hyperparathyroidism while the screening for gastroenteropancreatic (GEP) lesions was carried out in patients with both pituitary and parathyroid lesions. PATIENTS AND MEASUREMENTS: Serum total and ionized calcium, phosphate and intact PTH 1-84 (EASIA) were measured in 166 patients (68 with non-functioning pituitary adenoma, 42 with prolactinoma, 35 with GH-secreting adenoma, 17-with ACTH-screening adenoma, 1 with TSH-secreting adenoma, 1 with FSH-secreting adenoma and 2 with an only alpha-subunit secreting adenoma) referred to our clinic from 1990 to 1996. Plasma gastrin, somatostatin, pancreatic polypeptide and vasoactive intestinal peptide were measured by RIA in patients with hyperparathyroidism. RESULTS: Eight of 166 patients (4.8%) were found to have primary hyperparathyroidism and among these 2 also had a gastrinoma while there was no evidence of other GEP tumours. Considering the tumour type, 6 had prolactinoma (14.3%), 1 GH-secreting adenoma (2.8%) and 1 non-functioning adenoma (1.5%). In most patients the diagnosis of pituitary tumour was made several years before that of hyperparathyroidism (from 1 to 15 years) although 6 patients had previously suffered from urolithiasis and one had undergone gastric resections for recurrent peptic ulcers. One patient was identified as a MEN 1 gene carrier and 2 had relatives with signs and symptoms referable to parathyroid or GEP lesions. CONCLUSIONS: The study shows a prevalence of 4.8% of primary hyperparathyroidism in unselected patients with known pituitary tumours similar to that reported in a previous study. By contrast, the prevalence of MEN 1 in patients with prolactinoma was definitely high (14.3%). In most patients the diagnosis of pituitary tumours was made several years before that of hyperparathyroidism. Although the patients were believed to harbour a sporadic pituitary tumour, most of them had had signs and/or symptoms referable to one or both of the other organs involved in MEN 1, often concomitantly with those of pituitary tumours. These data indicate that the diagnosis of MEN 1 syndrome is missed in a substantial proportion of patients with prolactinomas and therefore the screening of these patients for the syndrome is strongly recommended.

Adenoma↗
PubMed1997

Cyclic AMP and calcium in the transduction of hypothalamic neurohormone action in human pituitary tumors.

Although hypothalamic neurohormones were originally identified on the basis of their ability to influence hormone release from the target cells, it is at present clear that these agents are involved in the control of several biological processes that include cell proliferation and differentiation as well as hyperplasia and neoplastic transformation. Hypothalamic neurohormones bind specific receptors belonging to the G-protein-coupled receptor superfamily to generate intracellular effectors, in particular cAMP and calcium. Several in vivo and in vitro studies suggest the presence of functional and/or structural alterations in the receptor/effector molecules involved in the transduction of hypothalamic neurohormone action in the pituitary. The present study reports the frequent presence in pituitary tumors of cellular alterations that result in amplification of stimulatory signals, particularly activation of the cAMP-dependent pathway, and reduction of inhibitory inputs, both events having possible implications in tumor formation and/or progression.

Calcium↗
PubMed1997

Immunodetection of G proteins in human pituitary adenomas: evidence for a low expression of proteins of the Gi subfamily.

G proteins mediate signal transduction in a variety of cell systems. As the expression of these proteins has not yet been investigated in detail in human pituitary tumors, we evaluated the presence of G proteins in a series of tumors including six non-functioning adenomas, five GH-secreting adenomas, three prolactinomas and one TSH-secreting adenoma, using immunoblotting and immunohistochemistry. By immunoblotting, Gi1/2alpha was undetectable in six and barely detectable in nine tumors. A similar pattern of expression was observed by probing with the antibody to Gi3alpha, which detected a very weak band in 11 tumors and no protein in four. In contrast, using large amounts of membrane proteins (40 microg), both Gi1/2alpha and Gi3alpha were detected, although at very low levels, in the negative tumors. The low expression of these proteins appeared to be specific to tumoral tissues, as both Gi1/2alpha and Gi3alpha were abundant in normal human and rat pituitary. In all tumors, Go alpha, the two Gs alpha forms, Gq/11 and G beta were present in significant amounts. Semiquantitative analysis indicated that Gs alpha was clearly detected when 2.5 microg loaded proteins were used, whereas Gi1/2alpha and Gi3alpha were barely detected with 5 microg. By immunofluorescence, all tumors studied were markedly positive for Gs alpha that was immunolocalized at the cell periphery, whereas they showed a weak positivity for Gi1/2alpha and Gi3alpha. The study is the first to provide evidence for a low expression of Gi proteins, which are involved in the transduction of inhibitory signals, in pituitary adenomas.

Adenoma↗
PubMed1996

Adjuvant immunotherapy treatment of renal carcinoma patients with autologous tumor cells and bacillus Calmette-Guèrin: five-year results of a prospective randomized study.

BACKGROUND: Active specific immunotherapy (ASI) is a strategy that attempts to boost the host's immune response specifically against its own tumor. The purpose of this study was to investigate the effect of adjuvant ASI in patients with renal carcinoma. METHODS: Of 120 consecutive patients, 60 were randomized to a control group and 60 to receive ASI comprised of 3 intradermal injections of 10(7) autologous irradiated tumor cells mixed with 10(7) Bacillus Calmette-Guèrin (in the first 2 vaccinations) or alone. At randomization and 1, 6, and 12 months after completing immunotherapy, the treated patients were evaluated for the development of delayed type cutaneous hypersensitivity (DTCH) response to autologous tumor and autologous normal renal cells. RESULTS: The baseline DTCH responses were negative in all patients. One month after completing ASI, 38 of 54 immunized patients showed a significant (P<0.01) DTCH response to autologous tumor but not to autologous normal renal cells. The response was persistent at 6 months in 25 of 44 patients and at 12 months in 16 of 28 patients. DTCH response remained negative in the nonimmunized control patients. There was no systemic toxicity but local ulcerations that healed in 2 months were observed. After a median follow-up of 61 months, the probability of 5-year disease free survival (DFS) was 63% for treated patients and 72% for control patients. The corresponding probability of 5-year overall survival (OS) was 69% and 78%, respectively. These differences were not statistically significant. CONCLUSIONS: This is the first prospective randomized study of ASI in a large population of patients with renal carcinoma after radical nephrectomy. Our data clearly indicate that ASI can increase the reactivity to autologous tumor, as measured by the DTCH test, but it appears unable to affect DFS and OS of patients.

Adjuvants, Immunologic↗
PubMed1996

Cellular abnormalities in pituitary tumors.

Pituitary cells appear to be programmed to proliferate in response to cyclic adenosine monophosphate (cAMP), leading to tumorigenesis. Stimulatory neurohormones and inhibitory inputs normally act in opposition to control cAMP levels, but receptor/postreceptor alterations may affect their relative effects. Most growth hormone (GH), corticotropin (ACTH)-, prolactin (PRL)-, and gonadotropin-secreting adenomas and nonfunctioning pituitary adenomas (NFPA) possess specific thyrotropin-releasing hormone (TRH) receptors, normally coupled with cytosolic [Ca2+]i increase and diacyl glycerol production. These cells are also sensitive to other peptides such as vasoactive intestinal peptide (VIP) and pituitary adenylyl cyclase-activating peptide (PACAP), which activate adenylyl cyclase in many hormone-secreting adenomas and in all NFPA. The two main inhibitory agents controlling pituitary function are somatostatin (SS) and dopamine (DA), which have been reported to reduce hormone hypersecretion and tumor growth in a variable percentage of patients. Inhibition of adenylyl cyclase activity and cytosolic [Ca2-]i levels is involved in the transduction of DA signals in normal and tumoral mammotrophs, but in GH-secreting adenomas DA receptors are exclusively and defectively coupled only with [Ca2+]i reduction. The abnormal expression of these receptors can amplify stimulatory signals with both secretory and proliferative potential. The availability of specific G proteins may qualify the cell response to inhibitory agents. For example, in a subset of NFPA, SS alone or DA alone causes an abnormal increase in [Ca2+]i levels due to Ca2+ mobilization from intracellular stores.

Animals↗
PubMed1996

GS protein mutations and pituitary tumors: functional correlates and possible therapeutic implications.

In more than one third of growth hormone (GH)-secreting pituitary adenomas, a point mutation in the gene for the alpha-chain of the G stimulatory protein (gsp oncogene) causes the constitutive activation of the membrane adenylyl cyclase (AC) resulting in uncontrolled cyclic adenosine monophosphate (cAMP) elevation and GH hypersecretion. Tumors expressing gsp are characterized by high membrane AC activity, elevated intracellular cAMP content, and high rates of GH release in culture medium. The AC activity is not further stimulated by GH-releasing hormone (GHRH) and other specific and non-specific agents, while it is lowered by somatostatin, as the G inhibitory protein (Gi) is normally working. Acromegalic patients bearing adenomas with the gsp mutation do not present with any obvious clinical or epidemiological distinctive features. However, they have smaller tumors in relation to their circulating GH levels, suggesting that the gsp oncogene maintains a high rate of secretory activity in vivo. Most of these patients show paradoxical GH increases to thyrotropin-releasing hormone (TRH), but none to gonadotropin-releasing hormone (GnRH) or an oral glucose tolerance test (OGTT). As with the in vitro data, these patients are not very sensitive to GHRH administration, but are sensitive to the inhibitory action of somatostatin. In our experience, only three of six patients with non-gsp-mutated tumors had lowered serum GH levels during the administration of octreotide (100 micrograms thrice daily for 4 years), while all of six patients with gsp-mutated tumors had serum GH levels suppressed by octreotide treatment. Such a good GH suppressibility by somatostatin makes patients with gsp-mutated tumors the best candidates for medical treatment with somatostatin analogs.

Acromegaly↗