Loss of heterozygosity at the SS receptor type 5 locus in human GH- and TSH-secreting pituitary adenomas

SS receptor types 2 and 5 (sst2 and sst5) are involved in the control of secretion and proliferation of normal and tumoral somatotrophs and thyrotrophs. The mechanisms leading to reduced responsiveness to SS analogues in patients with pituitary tumors are poorly understood. The aim of the study was to verify the possible loss of heterozygosity (LOH) at the sst5 gene locus in somatotroph and thyrotroph adenomas by screening leukocyte and tumor DNA for two single nucleotide polymorphisms, i.e. C1004T leading to P335L change and T-461C in the 5'-upstream region. Among the 13 informative samples, 1 GH- and 1 TSH-secreting adenoma showed LOH at sst5 gene locus with the retention of Leu335 variant. By analyzing other polymorphic markers spanning from telomere to 16p13.3-13.2 boundaries, DNA deletion of at least 1 megabase was found in both tumors. LOH in thyrotroph adenoma was associated with unusual tumor aggressiveness that required a second surgery and resistance to SS analogs, while no obvious phenotype was identified in the case of the somatotroph adenoma. In conclusions, LOH at the sst5 gene locus is a rare phenomenon, occurring in about 10% of pituitary tumors, that seems to be associated with an aggressive phenotype, at least in thyrotroph adenomas. Further studies are required to confirm this association and to identify the genes, in addition to sst5, lost in these tumors.

Assessing the presence of abnormal regulation of cortisol secretion by membrane hormone receptors: in vivo and in vitro studies in patients with functioning and non-functioning adrenal adenoma

Regulation of cortisol secretion by aberrant hormone receptors may play a role in the pathogenesis of ACTH-independent Cushing's syndrome. In this study, the topic was evaluated by combining in vivo and in vitro approaches. Cortisol responses to various stimuli (standard meal, GnRH + TRH, cisapride, vasopressin, glucagon) were assessed in 6 patients with clinical or subclinical adrenal Cushing's syndrome, and non-functioning adrenal adenoma in two cases. Abnormal responses were observed in three patients with Cushing's syndrome; one patient showed a gastric inhibitory polypeptide (GIP)-dependent cortisol rise after meal, together with responses after GnRH and cisapride; the second patient showed an LH-dependent cortisol response to GnRH, and in the third cortisol rose after cisapride. The pattern of receptor expression performed by RT-PCR showed that while GIP-R was only expressed in tumor from the responsive patient, 5-hydroxytryptamine type 4 receptor and LH-R were also present in normal adrenal tissues and tissues from non-responsive patients. Interestingly, an activating mutation of Gsalpha gene was identified in one of these tumors. Therefore, cortisol responses to agents operating via Gs protein coupled receptors (in one case associated with Gsalpha mutation) were found in Cushing's patients, while these responses were absent in the others. The finding of receptor expression in normal and non-responsive tumors suggests that different mechanisms are probably involved in inducing in vivo cortisol responses.

Circulating adiponectin levels and cardiovascular risk factors in acromegalic patients

OBJECTIVE

Adiponectin (ApN) is an adipocytokine expressed in human adipose cells with anti-atherogenic and anti-inflammatory properties that plays a role in the pathophysiology of insulin resistance, metabolic syndrome and coronary artery disease. The aim of the study was to evaluate ApN secretion in patients with acromegaly, a chronic disease associated with insulin resistance and increased cardiovascular mortality, and to correlate ApN levels with hormonal, metabolic and cardiovascular parameters.

DESIGN AND METHODS

The study included 32 patients with active acromegaly (11 male and 21 female, aged 48+/-11 years, duration of disease: 8+/-6 years, GH: 9.2+/-9.8 microg/l, IGF-I: 80+/-33 nmol/l (means+/-s.d.)) and 38 control subjects sex- and body mass index (BMI)-matched. In all subjects, serum ApN, leptin and ghrelin levels, BMI, waist circumference, insulin resistance (assessed by homeostasis model assessment and the quantitative insulin check index), lipid profile and blood pressure values were evaluated.

RESULTS

Acromegalic patients and control subjects had similar ApN levels (9.4+/-3.5 vs 9.5+/-4.0 mg/l, NS), while when considering obese subjects acromegalic patients had ApN levels significantly higher than controls (10.2+/-4 vs 7.5+/-3 mg/l, P<0.05). No significant correlation between ApN and GH/IGF-I levels or duration of disease was found. ApN concentrations negatively correlated with BMI, waist circumference, glucose and diastolic blood pressure and positively with high-density lipoprotein cholesterol and ghrelin in controls, while all these correlations were lost in acromegalic patients.

CONCLUSIONS

We provide evidence that, although metabolic and cardiovascular abnormalities are present in most acromegalic patients, in these subjects ApN levels are not reduced and, contrary to what is found in BMI-matched controls, do not correlate with cardiovascular risk factors. These data support the view that atherosclerosis is not the main determinant of cardiovascular mortality in acromegaly and suggest a permissive action of GH and/or IGF-I excess on ApN secretion.

Gonadotropin-releasing hormone initiates multiple signaling pathways in human GH-secreting adenomas

Abnormal GH responses to GnRH test, observed in about 15% of patients with acromegaly, have been reported exclusively in patients bearing tumors without gsp mutation. The absence of responsiveness to GnRH in gsp+ tumors was not predicted on the basis of the mechanism of GnRH action that mainly involves the activation of calcium and protein kinase C dependent pathways. The aim of the present study was to investigate in detail the transduction of GnRH signaling in these tumors. GH-secreting adenomas removed from patients in vivo responsive to GnRH test were studied. Tumor DNA was screened for Gsalpha and GnRH receptor gene sequences. Intracellular calcium ([Ca2+]i) and cAMP levels were measured in dispersed cells and adenylyl cyclase (AC) activity in membrane preparations. DNA analysis showed wild sequence of both Gsalpha and GnRH receptor genes. GnRH caused a significant increase in intracellular Ca2+ that was associated with a significant stimulation of cAMP accumulation. In these cells neither TRH nor GHRP-6 were effective in causing significant modifications of cAMP levels, despite their ability to increase [Ca2+]i. Finally, GnRH was able to directly stimulate AC from 11.1 +/- 3.3 pmol/mg prot/min to 26.9 +/- 5.4 (p<0.005). We report that GnRH was effective in increasing both [Ca2+]i and AC in GH-secreting adenomas removed from responsive patients. The ability of GnRH to signal through Gsalpha protein may account for the lack of GH responses to GnRH observed in acromegalic patients with tumors carrying gsp mutation.

Evidence of a secondary grapevine domestication centre detected by SSR analysis

The origin of the grapevine was investigated with archaeobotanical, cultural and historical data. A primary domestication centre was located in the Near East region but there is no agreement on the existence or role of secondary domestication centres. In this work, PCR-based microsatellite analysis has been applied to study the origin of some Italian cultivated grapevines from in situ direct domestication of the wild autoctonous grapevine. Three different Italian locations in Grosseto, Cosenza and Nuoro were identified for this study, and domesticated grapevine as well as wild local accessions growing in these location, were analysed by SSR markers. Cluster analysis performed on Cosenza and Grosseto samples showed a high value of genetic distance between domesticated and wild accessions. On the contrary two cultivars (Bovale Murru and Bovale Muristellu) recovered in Nuoro (in the Sardinia island) were very close to some wild varieties. This suggests that the latter two cultivars may have originated from wild grapevines and consequently that in this location a secondary grapevine domestication event occurred. Six Lambrusco varieties were also included in this analysis as ancient putative ancestors of the cultivated grapevines. The molecular analysis excluded this hypothesis and suggest Lambrusco as an independent Vitis taxon.

Ghrelin secretion in severely obese subjects before and after a 3-week integrated body mass reduction program

Ghrelin, the endogenous ligand of GH-secretagogue receptors, has been implicated in the regulation of feeding behavior and energy balance. Aim of the study was to investigate ghrelin levels in fasting conditions and after a standard meal test in obese subjects before and after a 3-week integrated body weight reduction (BWR) program (consisting of energy-restricted diet, exercise training, psychological counselling and nutritional education). Weight, height, fat mass, fat free mass (by impedentiometry), circulating ghrelin, insulin and leptin levels were evaluated in 10 obese subjects (3 male, 7 female; mean age: 35 +/- 9.3 yr; body mass index BMI: 45.2 +/- 10.6 kg/m2) before and after weight reduction. At baseline, obese subjects showed significantly lower ghrelin levels than controls, which were negatively correlated with BMI, weight, insulin and leptin levels. Fasting ghrelin levels were not modified by standard meal test in obese subjects (from 110.8 +/- 69.7 to 91.8 +/- 70.2 pmol/l p=ns), while a significant reduction was observed in controls (from 352.4 +/- 176.7 to 199.0 +/- 105.2 pmol/l; p<0.01). After a 3-week integrated BWR program obese subjects significantly reduced weight, BMI and leptin levels, while no significant changes were found both in fasting ghrelin and in ghrelin response after the meal. In conclusion, 5% weight loss obtained after a short-term period of integrated BWR program is not sufficient to normalize fasting ghrelin levels nor to restore the normal ghrelin suppression after a meal in severely obese subjects.

Circulating ghrelin levels in patients with pancreatic and gastrointestinal neuroendocrine tumors: identification of one pancreatic ghrelinoma

Ghrelin is a novel gastrointestinal hormone involved in several metabolic functions. Although the expression of ghrelin has been demonstrated in most gastrointestinal carcinoids and pancreatic tumors, the circulating levels of this peptide have been marginally assessed in patients with these disorders. We measured plasma ghrelin levels in 16 patients with gastrointestinal carcinoid (10 with midgut and 6 with gastric carcinoid), 24 patients with pancreatic tumor (8 with gastrinoma, 2 with insulinoma, 2 with vipoma, 1 with glucagonoma, and 11 with nonfunctioning tumor), and 35 healthy controls. Plasma ghrelin levels recorded in patients with gastroenteropancreatic tumors were similar to controls (mean +/- SE, 182.7 +/- 66.5 pM in patients vs. 329 +/- 32 pM in controls, P = not significant), and no significant difference between gastrointestinal and pancreatic, functioning and nonfunctioning, and metastatic and nonmetastatic tumors was observed. One patient with metastatic nonfunctioning pancreatic tumor had circulating ghrelin levels of 12,000 pM that were slightly reduced during chemotherapy and interferon therapy. Immunohistochemistry performed on peritoneal lesions showed an intense, focal cytoplasmic positivity for ghrelin. Despite the 50-fold increase in ghrelin concentrations, the patient had normal serum GH and IGF-I levels. In conclusion, the study showed that carcinoids and pancreatic tumors rarely cause ghrelin hypersecretion. However, in this series, 1 pancreatic ghrelinoma not associated with clinical features of acromegaly was identified.

Brown jaw tumors: today's unusual presentation of primary hyperparathyroidism

Primary hyperparathyroidism (pHPT) has changed its clinical features in the last decade becoming a mild biochemical disease, in which the classical fibrous cystic osteitis is a rare complication. The more frequent bone involvement in primary hyperparathyroidism is observed at the distal 1/3 of the radius, where the cortical bone is primarily represented. However, lumbar and femoral osteopenia or osteoporosis prevalently affect hyperparathyroid post-menopausal women. We report two, otherwise healthy, young male patients, who presented a painful jaw swelling. In both patients standard radiographic imaging revealed a low-density well-defined lesion, which caused jaw bone destruction. High levels of serum calcium (14.1-16.6 mg/dl, n.v. 8.1-10.4) and PTH (1172-1928 pg/ml, n.v. 10-65) indicated the presence of pHPT associated with hypertension, asymptomatic renal involvement and osteoporosis with normal serum 25-hydroxyvitamin D levels in both patients. A single huge parathyroid adenoma was successfully removed and within 2 months jaw lesions were almost completely re-mineralized without any other therapeutic intervention in both patients. In conclusion, although brown jaw tumors are a rare complication of the hyperparathyroidism, they should be considered and identified in young patients with severe pHPT. Moreover, such a complication seems to be independent from vitamin D deficiency, suggesting the involvement of other pathogenetic factors.

Effects of hypothalamic neuropeptides on extracellular signal-regulated kinase (ERK1 and ERK2) cascade in human tumoral pituitary cells

The G protein-coupled receptor (GPCR) activation has been demonstrated to affect the ERK1/2 cascade in different cell lines. We investigated the effects of hypothalamic neuropeptides acting via GPCR on this pathway in GH-secreting (GH-oma) and nonsecreting (NFPA) pituitary adenomas. GHRH increased ERK1/2 activity (236 +/- 80%) in both gsp- and gsp+ GH-omas, this effect being almost completely abolished by protein kinase C (PKC) blockade. Both GnRH and pituitary adenylate-activating peptide caused a similar PKC-dependent activation of ERK1/2 in most NFPA. Increasing cAMP by forskolin caused a protein kinase A-dependent increase of ERK activity (287 +/- 37%) in GH-omas and had no effect in NFPA. ERK cascade blockade in GH-omas did not affect basal and GHRH-stimulated GH release, whereas it totally prevented the 3-fold increase in cyclin D1 protein expression induced by GHRH. In conclusion, this study demonstrated that in pituitary adenomas the activation of GPCR by neurohormones caused a PKC-dependent activation of ERK1/2 cascade that, at least in GH-omas, resulted to be involved in cyclin D1 induction by GHRH. Moreover, a stimulatory effect of the protein kinase A-dependent pathway on ERK1/2 cascade occurred selectively in GH-omas, probably contributing to the mitogenic potential of the cAMP pathway in this cell type.

[Genetic changes in human pituitary adenomas]

In the last few years molecular biology technologies have provided important insights into mechanisms possibly involved in pituitary tumor formation. Several evidences indicate that the majority of pituitary adenomas is monoclonal, thus implying that they derive from the replication of a single mutant cell. In about 30-40% of GH-secreting adenomas mutations at codon 201 and 227 of GNAS1 gene that codes for the Gs alpha subunit have been identified. These mutations, named gsp for Gs protein, cause the constitutive, hormone-independent, activation of adenylyl cyclase and consequent overproduction of cAMP, that is mitogenic in somatotropes. Screening studies carried out on large series of acromegalic patients carrying tumors with or without gsp oncogene failed to detect clinical differences between the two groups. The existence of mechanisms induced by gsp mutations and able to counteract the mitogenic potential of this oncogene has been hypothesized. In particular, several events including the low expression of mutant Gs, the induction of phosphodiesterases, that are involved in cAMP degradation, and of the inducible cAMP early repressor (ICER) that represses cAMP induced gene expression, together with a high sensitivity to somatostatin have been characterized in gsp positive tumors. As far as the loss of oncosuppressors is concerned, no mutations of these genes have been so far reported, while they are frequently expressed at low levels in pituitary tumors. However, the nature of initiating and promoting events involved in tumor formation remains to be clarified in the majority of pituitary tumors.

Plasma chromogranin A in patients with sporadic gastro-entero-pancreatic neuroendocrine tumors or multiple endocrine neoplasia type 1

OBJECTIVE

As circulating chromogranin A (CgA) has been claimed to be the best general neuroendocrine marker so far available, we evaluated the usefulness of CgA determination in the clinical assessment of patients with sporadic gastro-entero-pancreatic neuroendocrine tumors (GEP NETs) or multiple endocrine neoplasia type 1 (MEN 1).

DESIGN AND METHODS

Plasma CgA levels were measured using a commercial enzyme-linked immunosorbent assay in 61 patients with sporadic GEP NET and in 25 with MEN 1 including 16 with GEP NET. Controls were 50 healthy volunteers, 46 patients with pituitary adenoma and 35 patients with primary hyperparathyroidism.

RESULTS

The cutoff value for CgA established in our healthy subjects (as mean+2 s.d.) was 20 U/l. CgA levels were above the normal range in 71/77 patients with sporadic or MEN 1-related GEP NETs (92%), in four out of nine MEN 1 patients without GEP NETs (44%), and only in 22/81 control patients with pituitary or parathyroid disease (27%). Furthermore, CgA levels of over 100 U/l occurred in 36/77 patients with GEP NETs (47%) and only in one patient with a non-functioning pituitary adenoma. In the patients with GEP NETs, both tumor burden and secretory activity affected CgA levels, and successful surgical resection was associated with markedly decreased CgA values.

CONCLUSIONS

Plasma CgA was confirmed to be a reliable marker for GEP NETs. Moreover, in MEN 1 patients the finding of very high CgA levels strongly suggests the presence of a GEP NET, as both primary hyperparathyroidism and pituitary adenomas rarely cause marked CgA increases.

Mitogen-activated protein kinase cascade in human normal and tumoral parathyroid cells

The calcium-sensing receptor (CaR) activation has recently been shown to modulate the ERK1 and ERK2 cascade in different cell lines. The present study investigated this pathway in human normal and tumoral parathyroid cells. In cells from normal parathyroids and almost all hyperplasia increasing extracellular calcium concentrations (Ca(o)(2+)) induced a significant activation of ERK1 and -2, the percent stimulation over basal activity (at 0.5 mM Ca(o)(2+)) being 545 +/- 140 and 800 +/- 205 in normal cells and 290 +/- 71 and 350 +/- 73 in hyperplasia at 1 and 2 mM Ca(o)(2+), respectively. This effect was mediated by CaR because it was mimicked by the receptor agonist gadolinium and neomycin. Basal and Ca(o)(2+)-stimulated ERK1 and -2 activity was nearly abolished by the PKC inhibitor calphostin C, and PKA changes did not affect ERK1 and -2 activity. PI3K blockade by wortmannin, known to prevent G protein betagamma subunit effect on ERK1 and -2, induced a 30% reduction of the Ca(o)(2+)-stimulated ERK1 and -2 activity. Adenomatous cells showed high PKC-dependent ERK1 and -2 activity in resting conditions that was unresponsive to high Ca(o)(2+). A role of MAPK on PTH secretion was suggested by the finding that PD98059, a specific MEK inhibitor, abolished the inhibitory effect of 1.5 mM Ca(o)(2+) on PTH release from normal parathyroid cells. In conclusion, these data first demonstrate that CaR activation, through the PKC pathway and, to a lesser extent, PI3K, increases ERK1 and -2 activity in normal parathyroid cells and this cascade seems to be involved in the modulation of PTH secretion by Ca(o)(2+). Interestingly, this signaling pathway is disrupted in parathyroid tumors.

Impaired estrogen-induced negative feedback on gonadotropin secretion in patients with gonadotropin-secreting and nonfunctioning pituitary adenomas

BACKGROUND

Several in vitro studies suggest that gonadotropin-secreting pituitary adenomas (Gn-omas) and non functioning pituitary adenomas (NFPA) originate from gonadotroph cells. Patients with Gn-oma and NFPA frequently show abnormal gonadotropin response to TRH. The aim of the study was to investigate whether the estrogen-induced negative feedback is operating in either patients with Gn-oma or NFPA.

MATERIALS AND METHODS

Serum gonadotropin levels were evaluated at 24 h after ethinylestradiol administration (1 mg per os; EE2 test) in seven patients with a diagnosis of Gn-oma, based on the presence of high follicle-stimulating hormone (FSH) and/or lutenising hormone (LH) levels with normal or high levels of sex steroids, in 22 patients with NFPA with normal or low levels of gonadotropin and sex steroids, and 30 sex- and age-matched healthy subjects. A normal response to EE2 test was arbitrarily defined as a serum LH and FSH decrease of at least 40 and 30% below basal levels.

RESULTS

Among patients with Gn-oma, only one had a normal FSH inhibition and another, a normal LH inhibition. Among the 22 patients with NFPA, the EE2 test caused a normal FSH or LH reduction in 10 and 15, respectively, while a normal reduction of both FSH and LH was observed in nine.

CONCLUSIONS

The study demonstrates that estrogen-induced negative feedback of gonadotropin secretion is disrupted in almost all patients with Gn-oma and in half of those with NFPA. This defective feedback is reminiscent of the resistance to thyroid hormones and glucocorticoids observed in patients with thyroid-stimulating hormone- (TSH-) and adrenocorticotropic hormone- (ACTH-)secreting adenomas, respectively.

G protein mutations in endocrine diseases

This review summarizes the pathogenetic role of naturally occurring mutations of G protein genes in endocrine diseases. Although in vitro mutagenesis and transfection assays indicate that several G proteins have mitogenic potential, to date only two G proteins have been identified which harbor naturally occurring mutations, Gsalpha, the activator of adenylyl cyclase and Gi2alpha, which is involved in several functions, including adenylyl cyclase inhibition and ion channel modulation. The gene encoding Gsalpha (GNAS1) may be altered by loss or gain of function mutations. Indeed, heterozygous inactivating germ line mutations in this gene cause pseudohypoparathyroidism type Ia, in which physical features of Albright hereditary osteodystrophy (AHO) are associated with resistance to several hormones, i.e. PTH, TSH and gonadotropins, that activate Gs-coupled receptors or pseudopseudohypoparathyroidism in which AHO is the only clinical manifestation. Evidence suggests that the variable and tissue-specific hormone resistance observed in PHP Ia may result from tissue-specific imprinting of the GNAS1 gene, although the Gsalpha knockout model only in part reproduces the human AHO phenotype. Activating somatic Gsalpha mutations leading to cell proliferation have been identified in endocrine tumors constituted by cells in which cAMP is a mitogenic signal, i.e. GH-secreting pituitary adenomas, hyperfunctioning thyroid adenomas and Leydig cell tumors. When the same mutations occur very early in embryogenesis they cause McCune-Albright syndrome. Although these mutations would in principle confer growth advantage, studies failed to detect differences in the clinical and hormonal phenotypes, suggesting the existence of mechanisms able to counteract the activation of the cAMP pathway. Activating mutations of Gi2alpha have been identified in a subset of ovarian, adrenal and pituitary tumors, but their prevalence and significance are still controversial. Finally, although Galpha subunits are the only components of the heterotrimeric GTP binding proteins which harbor known mutations, beta/gamma subunits should be considered possible targets of genetic alterations as suggested by the frequent presence of beta3 subunit variants in patients with essential hypertension.

Prognostic value of the acute DMSA scan in children with first urinary tract infection

We attempted to verify in a group of 101 children with first urinary tract infection whether it was possible to identify groups of patients with different risks of developing renal scarring by taking into account both the extent of kidney involvement documented in the acute phase of infection using a dimercaptosuccinic acid (DMSA) scan, and the presence or absence of vesicoureteral reflux (VUR). The frequency of persistent lesions in kidneys with mild-moderate lesions (less than 50% of kidney involvement) in the presence of VUR or in non-refluxing kidneys was similar (P=0.1447), while the frequency of persistent lesions in kidneys with severe lesions in the presence of VUR was significantly higher than the frequency of persistent lesions in non-refluxing kidneys (P=0.0089). The extent of kidney involvement and the presence of VUR make possible the identification of different categories of risk of scarring: in the "low risk group" (normal kidney with/without VUR) the risk of scarring is 0%; in the "intermediate risk group" (mild lesions with/without VUR; extensive lesions without VUR) the risk of scarring is between 14% and 38%, while in the "high risk group" (extensive lesions with VUR) the risk of scarring is 88%. Quantifying the risk of scarring could help in planning the treatment or in modifying the later strategy.

In vitro release of activin A from human normal and pathological thyroid tissues

Activin A is a dimeric glycoprotein belonging to the transforming growth factor beta (TGF-beta) superfamily characterized by the ability to affect FSH secretion. Activin A was originally indicated as a gonadal product but the expression of activin A has been successively identified in several different tissues, including the thyroid gland. The aim of this study was to evaluate the release of activin A from human normal and pathological thyroid tissues in culture. Activin A concentration was evaluated in media obtained from primary culture of perinodular normal tissues (no.=2), hyperplastic hyperfunctioning thyroid tissues due to Graves' disease (no.=3) and autonomous thyroid adenomas (no.=3). Detectable levels of activin A were found in the incubation media from all tissues, without significant differences between normal and pathological samples. We conclude that activin A is secreted by follicle thyroid cells in normal and pathological conditions.

Acute renal cortical scintigraphy in children with a first urinary tract infection

This prospective study, performed in 101 children with a first symptomatic urinary tract infection (UTI), evaluates the diagnostic value of clinical, biological, and ultrasound parameters in detecting children with acute renal infection documented by dimercaptosuccinic acid (DMSA) scintigraphy. In children with a positive DMSA scan, mean C-reactive protein (CRP) was higher than in children with a normal DMSA scan (114+/-64 vs. 67+/-38 mg/dl, mean+/-SD, P=0.0002). The sensitivity and specificity of CRP was 64% and 68%, respectively. In children with severe kidney involvement, mean CRP and white blood count (WBC) were higher than in children with mild/moderate disease (151+/-83 vs. 92+/-55 mg/dl for CRP, P=0.0149; 20,100+/-6,854 vs. 15,023+/-6,145 WBC/ mm3 for WBC, P=0.0131). The sensitivity and specificity was 85% and 20% for CRP, and 77% and 18% for WBC, respectively. One or more areas of abnormal cortical echogenicity were documented in 3% of kidneys with positive DMSA scans. Dilatation of the collecting system was observed in 24% of kidneys. The sensitivity and specificity of ultrasonography was 27% and 89%, respectively. In conclusion, clinical, biological, and ultrasound parameters do not accurately distinguish cystitis from pyelonephritis in children with UTI and do not identify children with severe renal damage. Accordingly, we recommend that DMSA scan should be added to the initial work-up of children with UTI.

Genesis of pituitary adenomas: state of the art

In recent years, remarkable progress has been made in the understanding of the pathogenesis of pituitary tumors. Pituitary tumors originate from the uncontrolled proliferation of a single transformed cell in which an initiating event has caused a gain of proliferative function. After the initiation, promoting factors cooperate in the clonal expansion. Common oncogenes, such as ras, are only exceptionally involved. The only activating mutations identified so far are gsp mutations causing the constitutive activation of cAMP pathway. However, gsp-positive adenomas are not associated to a more aggressive tumoral phenotype. The oncogenic potential of gsp mutations is limited by a more rapid degradation of the mutant Gs(alpha) with respect to the wild-type protein, and by a faster removal of cAMP due to increased phosphodiesterase activity. Estrogen-inducible gene sequences with transforming properties (pituitary tumor-transforming gene (PTTG)) have been identified in human pituitary tumors. Human pituitary tumor-transforming gene (hPTTG) is involved both in early pituitary tumorigenesis, as it causes in vitro and in vivo transformation acting as a transcription activator, and in tumor progression, as it regulates the production of basic fibroblast growth factor (bFGF), a potent activator of angiogenesis and mitogenesis. Moreover, a role of cyclin D1 in pituitary tumorigenesis is emerging. The allelic loss of loci for unknown oncosuppressor genes are currently under investigation, while an exceedingly limited role for menin gene and RB1 has been demonstrated for sporadic pituitary tumors. Abnormal methylation that predisposing toward genetic instability may favor the allelic loss or the reduced expression of oncosuppressor genes, is also an emerging field of investigation. Several promoting factors, including the excessive action of physiological stimulators, the defective action of inhibitors, the susceptibility to respond to inappropriate stimuli and the locally produced growth factors, help in tumor progression. The study of homeobox genes that intervene in pituitary cell differentiation may help in expanding our knowledge in pituitary tumor cell genealogy.

Absence of thyroid transcription factor-1 expression in human parathyroid and pituitary glands

Thyroid transcription factor-1 (TTF-1), a tissue-specific nuclear transcription factor involved in the embryogenesis and differentiation of human thyroid, lung and brain, has been recently identified in other rat tissues, including parafollicular C cells and parathyroid chief cells. Based on this distribution, a possible role for this factor in calcium homeostasis has been suggested. This study investigated the presence of TTF-1 transcripts and protein in human tissues expressing the calcium sensing receptor (CaSR). Using a RT-PCR technique, complemented by Southern blot analysis, TTF-1 expression was detected in human C cells (two medullary thyroid carcinomas), but not in normal and adenomatous (four adenomas and three hyperplasia) parathyroid, and normal and adenomatous (six adenomas) pituitary tissues. CaSR was expressed in all samples. The absence of expression was confirmed by Western blot. In contrast to previous studies in the rat, this study demonstrates the absence of TTF-1 transcripts in the human adult parathyroid and pituitary glands, although a role for this factor during the ontogeny of these organs cannot be excluded.

Relevant cAMP-specific phosphodiesterase isoforms in human pituitary: effect of Gs(alpha) mutations

Both cAMP production by adenylyl cyclase and cAMP degradation by phosphodiesterases account for intracellular cAMP levels. We previously demonstrated an increased phosphodiesterase activity in GH-secreting adenomas bearing the gsp oncogene. Here we characterize both the activity and the expression of cAMP-specific phosphodiesterase genes in the human pituitary and in gsp+ and gsp- GH-secreting adenomas and analyze the impact of this intracellular feedback mechanism on the levels of cAMP-responsive element-binding protein phosphorylation. Normal pituitary and gsp- GH-secreting adenomas showed similar phosphodiesterase activities, and 7-fold higher levels were observed in gsp+ tumors. In these tumors the increased activity was mainly owing to isobutyl-methyl-xanthine-sensitive phosphodiesterase 4 and to isobutyl-methyl-xanthine-insensitive isoforms. By semiquantitative RT-PCR, all phosphodiesterase 4 transcripts were expressed in the normal and tumoral pituitary. However, the levels of phosphodiesterase 4C and 4D messenger RNAs were significantly higher in gsp+ than in gsp- GH-secreting adenomas and normal pituitary. Expression of the thyroid-specific isobutyl-methyl-xanthine-insensitive phosphodiesterase 8B was absent in the normal pituitary but detectable in almost all GH-secreting adenomas and higher in gsp+ (P < 0.02). Therefore, this study provides a characterization of phosphodiesterase expression in human pituitary and demonstrates a dramatic induction of the cAMP-specific phosphodiesterases 4C and phosphodiesterases 4D and phosphodiesterases 8B in gsp+ GH-secreting adenomas. Similar levels of cAMP-responsive element-binding protein phosphorylation were observed in gsp- and gsp+ GH-secreting adenomas; however, phosphodiesterase blockade caused an increase in cAMP-responsive element-binding protein phosphorylation that was significantly higher in gsp+ than in gsp- adenomas. Because cAMP-responsive element-binding protein represents the principal end point of the cAMP pathway, these results suggest that the enhanced phosphodiesterase activity may have a significant impact on the phenotypic expression of gsp mutations.

Activin A serum levels and aging of the pituitary-gonadal axis: a cross-sectional study in middle-aged and elderly healthy subjects

Aim of the study was to investigate activin A serum concentration in healthy adult males and post-menopausal females over a wide age-range and its correlation to gonadotropins, inhibin B and testosterone concentrations. The study included 73 males (aged 30-101 years) and 42 postmenopausal females (aged 50-104 years). Blood samples were collected after an overnight fast to measure serum activin A, inhibin B, LH, FSH, and gonadal steroid levels. A significant increase in serum activin A levels over age in both genders, especially in the oldest age-groups, was observed. Serum inhibin B and testosterone concentrations showed a sharp decrease in male subjects, reflecting the age-related decrease of testicular function and by consequence serum FSH and LH significantly increased. In female subjects LH and FSH levels were very high in subjects in their 50s and showed a continuous decline due to pituitary aging. Simple and multivariable regression analyses demonstrated the lack of correlation between activin A and FSH in both males and females. In conclusion, a steep increase in activin A levels is present during aging in both genders, especially in the last decades of life. The physiologic role and site of production of activin A in old subjects remain to be clarified.

Mutation of somatostatin receptor type 5 in an acromegalic patient resistant to somatostatin analog treatment

Introduction of somatostatin analogs has greatly contributed to improving the prognosis of acromegaly. Although the majority of patients are effectively treated by these agents, resistance occurs in a subset of patients. So far, resistance to somatostatin has never been associated with mutations of the somatostatin receptor subtypes (sst2 and sst5) that inhibit GH secretion. Molecular analysis of genomic DNA from pituitary tumor and peripheral blood obtained from an acromegalic resistant to octreotide showed a somatic activating mutation of Gsalpha (Arg201Cys), no mutation in sst2, and one polymorphism (Pro109Ser) and one germ line mutation (Arg240Trp) in sst5. Wild-type (WT) and mutant sst5 PCR products were cloned and transfected into Chinese hamster ovary K1 cells. In Chinese hamster ovary K1 cells stably expressing mutant sst5, somatostatin-28 was less potent in inhibiting cyclic AMP levels than in WT cells. Proliferation of mutant cells exceeded that of WT by 50%. Moreover, somatostatin reduced cell growth and MAPK activity in WT but not in mutant cells in which the peptide even increased MAPK activity. We suggest that this mutation that abrogates the antiproliferative action of somatostatin and activates mitogenic pathways may be involved in the resistance to somatostatin treatment.

Expression of cyclic adenosine 3',5'-monophosphate (cAMP)-responsive element binding protein and inducible-cAMP early repressor genes in growth hormone-secreting pituitary adenomas with or without mutations of the Gsalpha gene

In about 30-40% of GH-secreting adenomas, gain-of-function mutations of the Gsalpha gene, which convert this gene into an oncogene termed gsp, occur. Gsalpha mutations have been related to pituitary tumorigenesis. We focused on 2 nuclear transcription factors that are final targets of the cAMP-dependent pathway and are positively regulated by cAMP signaling, i.e. the cAMP-responsive element binding protein (CREB) and the inducible cAMP early repressor (ICER), that derives from alternative splicing of cAMP-responsive element modulator gene. We examined 21 GH-secreting adenomas, 8 with (gsp(+)) and 13 without (gsp(-)) a mutated Gsalpha. Analysis of CREB and ICER I/II messenger RNA revealed that the levels of both transcripts were higher in gsp(+) than in gsp(-) tumors (CREB/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mean optical density +/- SE, 2.34 +/- 0.36 in gsp(+) vs. 0.99 +/- 0.22 in gsp(-), P = 0.003; ICER I/GAPDH, 0.53 +/- 0.15 in gsp(+) vs. 0.14 +/- 0.07 in gsp(-), P = 0.01; ICER II/GAPDH, 1.5 +/- 0.21 in gsp(+) vs. 0.83 +/- 0.13 in gsp(-), P = 0.01), although a few cases in both groups did not display this pattern of expression. Moreover, no positive correlation between the levels of CREB and ICER transcripts was observed, suggesting the possible presence of alterations in the mechanisms by which cAMP signaling directs the expression of CREB and/or ICER genes. Our results indicate a complex pattern of expression of nuclear transcription factors that mediate cAMP action in both gsp(+) and gsp(-) tumors, suggesting that, beside Gsalpha gene mutations, different and partially unknown molecular events may contribute to the pathogenesis of these tumors.

Somatostatin receptor subtype 2 and 5 in human GH-secreting pituitary adenomas: analysis of gene sequence and mRNA expression

The role of somatostatin receptor subtypes 2 and 5 (SSTR2 and SSTR5) in determining the secretory and proliferative phenotype as well as the sensitivity to somatostatin analogue treatment is not clearly established. We quantified the expression of SSTR2 and SSTR5 mRNA using a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) in 19 human growth hormone (GH) -secreting adenomas. Tumour characteristics and in vivo sensitivity to somatostatin analogues were assessed; tumours were screened for Gsalpha gene mutations. PCR products of SSTR2 and SSTR5 DNA from tumours resistant to somatostatin analogues were directly sequenced. All tumours expressed both SSTR2 and SSTR5 mRNA at variable levels. No significant correlation between SSTR2 and SSTR5 expression and the presence of Gsalpha mutation, GH levels, or tumour size and invasiveness was observed. A negative correlation between SSTR2 and SSTR5 mRNA levels was observed (r = 0.5; P < 0.05). No significant correlation between the levels of SSTR2 and SSTR5 expression and the in vivo responsiveness to somatostatin analogues was observed, although a tendency to a low SSTR2 expression in resistant tumours was found. No mutations in the coding or bordering regions of either SSTR2 or SSTR5 adenomatous DNA from patients totally or partially resistant to somatostatin analogues were found. The study shows that the different expression of SSTR2 and SSTR5 in GH-secreting adenomas is not significantly correlated with the secretory and proliferative phenotype, although the large, hypersecretory tumours and those with a poor sensitivity to somatostatin analogues seem to express low levels of SSTR2 mRNA. Moreover, both SSTR2 and SSTR5 DNA from tumours resistant to somatostatin analogues were found to possess intact coding sequences.

Induction of heat shock protein 70 by herbimycin A and cyclopentenone prostaglandins in smooth muscle cells

This study characterizes Hsp70 induction in human smooth muscle cells (SMC) by herbimycin A and cyclopentenone prostaglandins. The magnitude of Hsp70 induction by cyclopentenone prostaglandins was 8- to 10-fold higher than induction by herbimycin A. Hsp70 induction by delta12PGJ2 was first observed at 10 microM, rose to 4000-5000 ng/mL within one log unit and a maximum response was not observed; concentrations of delta12PGJ2 higher than 30 microM were toxic to the cells. A maximum response with herbimycin A (500 ng/mL) was reached at 0.05 microM and maintained to 1 microM without toxicity. Both, delta12PGJ2 and herbimycin A, were inhibited by dithiothreitol (DTT, 100 microM) at lower concentrations and became less sensitive to inhibition at higher concentrations. Hsp70 induction after incubation of SMC with delta12PGJ2 followed by addition of herbimycin A was significantly higher than Hsp70 induction after incubation with herbimycin A followed by addition of delta12PGJ2. When cells were incubated with [3H]-PGJ2, followed by protein denaturation, substantial radioactivity remained protein-bound suggesting that the prostaglandin must be covalently bound. Covalent binding was largely insensitive to DTT. Maximal Hsp70 induction was observed after 5 minutes of exposure of the cells to herbimycin A followed by a 20 hour recovery period in agent-free medium. Cells required 3-4 hours of exposure to delta12PGJ2 followed by a 20 hour recovery period in order to see high Hsp70 induction. Binding of the heat shock factor (HSF) to the heat shock element (HSE) in the presence of herbimycin A or delta12PGJ2, and the effects of DTT, mirrored the results of Hsp70 induction. The results suggest that probable differences between the 2 agents are at the level of the signal transduction prior to HSF activation.

Genetic aspects of pituitary tumors

Pituitary adenomas arise from the replication of a single mutated cell in which growth advantage may result from either activation of protooncogenes or inactivation of antioncogenes. The search for oncogenes in the genesis of these tumors has yielded negative results except for the gsp oncogene, that has been identified in about 30-40% of GH-secreting adenomas. gsp mutations cause constitutive activation of the Gs alpha subunit, leading to elevated cAMP formation and growth hormone hypersecretion. In the remaining tumor types several lines of evidence suggest that genes implicated in cell proliferation, such as early immediate genes, growth factors and growth factor receptors, are overexpressed. As far as the loss of antioncogenes in pituitary adenomas is concerned, no inactivating mutations of these genes have yet been identified in pituitary adenomas. However, despite the lack of mutations, several antioncogene proteins have been detected at extremely low levels in pituitary adenomas, consistent with a possible role of these tumor suppressors in pituitary tumor formation.

Mutational analysis of GNAS1 in patients with pseudohypoparathyroidism: identification of two novel mutations

Pseudohypoparathyroidism (PHP) refers to two major variants that generally coexist in the same family, PHP type Ia (PHP Ia), in which both PTH resistance and a constellation of physical features, termed Albright's hereditary osteodystrophy (AHO), are present, and pseudopseudohypoparathyroidism (PPHP), in which AHO occurs without PTH resistance. Most patients with PHP Ia show a partial deficiency (50%) of Gs activity, due to loss of function mutations in Gsalpha gene (GNAS1). The present study reports clinical, biochemical, and molecular data of 8 unrelated families with PHP Ia and PPHP. The 13 exons of GNAS1 were screened for mutations by PCR and direct sequencing of the amplified products. We detected heterozygous mutations in the affected members of the 4 families in which PHP Ia was present. In 2 families 2 previously reported deletions in exons 5 and 7 were found, whereas in the other 2 families, 2 novel frameshift deletions were identified in exons 1 and 11, causing a premature stop codon in the mutant allele. No mutation was detected in the families in which PPHP was the only clinical manifestation. In conclusion, we report the first mutational analysis of Italian patients with PHP Ia and PPHP, and we describe two novel deletions in GNAS1. Furthermore, we confirm that these mutations cannot be detected in families with isolated PPHP, suggesting that these forms of AHO are genetically distinct from PHP Ia.

Induction of specific phosphodiesterase isoforms by constitutive activation of the cAMP pathway in autonomous thyroid adenomas

Thyrocytes largely depend on cAMP signaling for replication and differentiation. This pathway may be constitutively activated by mutations of the TSH receptor (TSHR) and Gsalpha in autonomous thyroid adenomas (ATAs). Because steady state cAMP results from production by adenylyl cyclase and degradation by phosphodiesterases (PDEs), we evaluated PDE activity and expression in ATAs with wild-type and mutant TSHR and Gsalpha. Activating mutations of TSHR and Gsalpha were identified in 7 and 1 of 18 ATAs, respectively. No difference was observed in the cAMP content in ATAs with or without activating mutants. In the surrounding normal thyroid tissue (NTs), PDE activity was 80% isobutylmethylxanthine sensitive, with the major contribution by PDE1 and a minor contribution by PDE4. No differences were observed in PDE activities between NTs and ATAs with wild-type TSHR and Gsalpha. In contrast, in the presence of mutant TSHRs or Gsalpha, total PDE activity was higher. This increase was primarily due to PDE4 induction (917 +/- 116% over NTs), associated with a minor PDE1 increase only in ATAs with mutant TSHR. By RT-PCR, increments of PDE4D and 4C messenger ribonucleic acids were found in the ATAs with mutant TSHR or Gsalpha, whereas messenger ribonucleic acids encoding other cAMP-specific PDEs were not significantly increased. This study provides a characterization of the PDEs expressed in human thyroid and demonstrates a dramatic PDE4 induction in the ATAs bearing mutant TSHR or Gsalpha genes. The increase in cAMP-degrading activity may represent a marker of constitutive adenylyl cyclase activation and constitutes an intracellular feedback mechanism with significant impact on the phenotypic expression of the activating mutations.

Introduction of heteroatom-based substituents into 1,4-dihydropyridines by means of a halogen-mediated, oxidative protocol: diamination, sulfonylation, sulfinylation, bis-sulfanylation, and halo-phosphonylation processes

The natural tendency of 1,4-dihydropyridines to undergo "biomimetic" oxidation to afford pyridinium salts can be switched off and, through the use of reagents that interact electrophilically with the enamine moiety present in the heterocyclic system, it is possible to promote alternative oxidations. In this way, efficient regio- and stereocontrolled synthetic methods have been developed that lead to diversely substituted di- and tetrahydropyridines. These include iodoazidation, diamination, bis-sulfonamidation, sulfonylation, sulfinylation, thiocyanation, sulfanylation, bis-sulfanylation, and halo-phosphonylation processes.

Peripheral blood neutrophils from hepatitis C virus-infected patients are replication sites of the virus

BACKGROUND AND OBJECTIVE

Hepatitis C virus (HCV) is able to cause not only acute and chronic liver disease, but also immunologic and hematologic disorders. In order to clarify the extra-hepatic tropism of HCV, and to understand the pathogenetic mechanisms of HCV infection, we evaluated viral replication in peripheral blood mononuclear cells.

DESIGN AND METHODS

The presence of genomic and antigenomic (replicative) forms of HCV in B- and T-lymphocytes, monocytes, and polymorphonuclear leukocytes (PML) was determined by reverse transcriptase-polymerase chain reaction in 54 HCV-RNA positive patients and, as control groups, in 10 patients who had recovered from HCV infection without evidence of serum HCV-RNA, and in 10 HCV-negative subjects.

RESULTS

In HCV-RNA positive patients, the genomic RNA was found in 94% of B-cells, in 14% of T-cells, in 40% of monocytes and in 77% of PML, while only 1 of the HCV-RNA negative subjects showed positivity in B-cells. The anti-genomic form of HCV-RNA was found in 52% of B-cells, in 3% of monocytes, and in 31% of PML. By contrast, it was never detected in T-cells and in HCV-RNA negative subjects. Neither genomic nor anti-genomic forms were found in HCV-negative cases.

INTERPRETATION AND CONCLUSIONS

These data suggest that PML are replication sites of HCV. Whether the infection occurs at the level of the stem cells or subsequently during myeloid cell differentiation is, as yet, unknown. The absence of correlation between the presence of replicative forms and any clinical and/or laboratory data opens the question of the role of HCV replication in extra-hepatic sites.

Calcium-sensing receptor expression and signalling in human parathyroid adenomas and primary hyperplasia

OBJECTIVE

Both in vivo and in vitro evidence indicates that primary hyperparathyroidism is characterized by a reduced sensitivity to extracellular calcium ([Ca2+]o). The existence of alterations in the expression and signalling of calcium sensing receptor (CaSR) in parathyroid neoplasia is still uncertain. In order to clarify the role of CaSR in the reduced [Ca2+]o sensing of parathyroid neoplasia we investigated PTH secretion and intracellular effectors triggered by CaSR activation as well as the levels of expression of CaSR and CaSR coupled G proteins (Gq/G11) in parathyroid adenomas and primary hyperplasia.

MATERIALS AND METHODS

The study included 27 parathyroid adenomas, 4 cases of primary hyperplasia and pools of normal parathyroid biopsies. Tissues were either snap frozen in liquid nitrogen or placed in sterile medium for cell dispersion. The effects of increasing [Ca2+]o on in vitro PTH release, intracellular cAMP levels and intracellular calcium ([Ca2+]i) in cells loaded with the Ca2 + indicator fura-2 were evaluated. CaSR mRNA levels were assessed by semiquantitative RT-PCR analysis, using GAPDH as internal standard, while CaSR protein was detected by western blot analysis using a specific polyclonal antibody. Purified antisera selective for G11alpha and Gqalpha were used to detect this class of proteins.

RESULTS

In basal conditions (at 0.5 mM [Ca2+]o) in vitro PTH released ranged from 29.4 to 1186 pg/well/60 minutes. Increasing [Ca2+]o from 0.5 to 1, 2.5 and 5 mM caused a variable effect. One group (n = 7) showed a significant but partial reduction of PTH release (of 17 to 60% of basal levels) that occurred at physiological [Ca2+]o concentrations (1 mM) while the remainder showed either inhibition detectable only at 2.5 mM (n = 15) or total (n = 9) resistance to [Ca2+]o. In the responsive cells, [Ca2+]o (1-5 mM) caused a pertussis toxin-insensitive [Ca2+]i rise (ranging from 10% to 260%), due to Ca2+ release from intracellular stores, and an inhibition of forskolin-stimulated cAMP levels. By RT-PCR almost all tumours tested showed a substantial reduction in CaSR mRNA levels when compared to the normal tissue (CaSR/GAPDH ratio: 3.1 +/- 0.5 vs. 15.5 +/- 3.1; P < 0.001), which was confirmed by immunoblotting analysis demonstrating low levels of CaSR protein in tumour tissues. Moreover, low amounts of G11alpha and Gqalpha, the G proteins involved in CaSR coupling, were observed in the majority of pathological tissues.

CONCLUSIONS

The study shows that the activation of the calcium sensing receptors expressed in adenomatous parathyroid glands modulates intracellular effectors in a similar way to those operating in the normal parathyroid. Although a reduction of calcium sensing receptor expression is probably involved in the poor inhibition of PTH release induced by [Ca2+]o, this is not the only factor altering [Ca2+]o sensing in parathyroid adenomas, since tumours characterized by different in vitro sensitivity to [Ca2+]o showed similar CaSR levels. The low content of G proteins of the Gq subfamily might represent an additional alteration leading to a defective [Ca2+]o sensing.

Effect of aging on serum gonadotropin levels in healthy subjects and patients with nonfunctioning pituitary adenomas

OBJECTIVE

Nonfunctioning pituitary adenomas (NFPA), which represent about one-quarter of human pituitary tumors, occur in middle or old age. Determination of gonadotropin levels, which are not expected to be high during the early postmenopause in normal women and which are low in women with NFPA, is important to distinguishing hypogonadal status due to the normal decline of gonadal function from that due to hypothlalamic-pituitary dysfunction. The aim of the study was to verify whether this difference still persists in old subjects, despite the physiological decline of gonadotropins in the last decades of life.

DESIGN AND METHODS

The study included 154 healthy subjects (aged 50-104 years) and 47 patients with NFPA (aged 50-80 years). Blood samples were collected after an overnight fast and hormone levels were measured by two immunofluorimetric assays.

RESULTS

In healthy women the highest serum levels of gonadotropins were present in the 50-60 year age group, with a slight but progressive age-associated decrease in serum FSH and LH being observed thereafter. In healthy men serum gonadotropin levels were stable up to 70 years, increased up to 75-85 years and thereafter gradually decreasing. Female patients with NFPA showed levels of gonadotropins which were far lower than controls. Only three patients had levels of both FSH and LH above the 2.5 centile for normal subjects. A high sensitivity and specificity of gonadotropin measurements (about 90%) for the diagnosis of NFPA was observed in female patients aged 50-80 years. In male subjects, a large overlap of gonadotropin values in NFPA and controls, namely over the 50-70 years age range, was observed.

CONCLUSIONS

Our study demonstrates that despite the gradual decline of gonadotropin levels in healthy postmenopsausal women, the reduction of both FSH and LH persists in old patients with NFPA, suggesting that measurement of gonadotropin levels could prove useful in the evaluation of pituitary lesions even in old women. More subtle differences seem to occur in male subjects.

A case of central nervous system vasculitis related to an episode of Guillain-Barrè syndrome

The authors report their knowledge about an uncommon case of isolated vasculitis, restricted to the left sylvian artery during an auto-immune Guillain-Barrè syndrome (GBS), sustained by cytomegalovirus (CMV). An acute cardiopulmonary failure requiring a ventilator and vasopressor support manifested, notwithstanding plasma exchanging and immune-modulating therapy. An IgM-enriched formula administration coincided with a rapid amelioration of GBS and vasculitis to a complete recovery the next month after her discharge to a rehabilitation centre.

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.

Aminoisoquinolines: design and synthesis of an orally active benzamidine isostere for the inhibition of factor XA

The design, synthesis and SAR of sulfonamidopyrrolidinone fXa inhibitors incorporating a new benzamidine isostere, namely aminoisoquinolines, is described. These inhibitors have higher Caco-2 cell permeability than comparable benzamidines and attain higher levels of exposure upon oral dosing. The most potent member 14b (fXa Ki=6 nM) is selective against other serine proteases of interest (>600 fold).

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.

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.

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.

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.

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.

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.

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.

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.