The dopaminergic control of Cushing's syndrome.

Cushing's Syndrome (CS), or chronic endogenous hypercortisolism, is a rare and serious disease due to corticotroph pituitary (Cushing's disease, CD) and extra-pituitary (ectopic CS) tumours overproducing ACTH, or cortisol-secreting adrenal tumours or lesions (adrenal CS). The first-line treatment for CS is represented by the surgical removal of the responsible tumour, but surgery might be unfeasible or ineffective and medical treatment can be required in a relevant percentage of patients with CS, especially CD and ectopic CS. Corticotroph pituitary and extra-pituitary tumours, as well as adrenal tumours and lesions responsible for CS express dopamine receptors (DRs), which have been found to mediate inhibition of hormone secretion and/or cell proliferation in experimental setting, suggesting that dopaminergic system, particularly DRs, might represent a target for the treatment of CS. Dopamine agonists (DAs), particularly cabergoline (CAB), are currently used as off-label treatment for CD, the most common form of CS, demonstrating efficacy in controlling hormone secretion and tumour growth in a relevant number of cases, with the improvement of clinical picture, and displaying good safety profile. Therefore, CAB may be considered a reasonable alternative treatment for persistent or recurrent CD after pituitary surgery failure, but occasionally also before pituitary surgery, as adjuvant treatment, or even instead of pituitary surgery as first-line treatment in case of surgery contraindications or refusal. A certain beneficial effect of CAB has been also reported in ectopic CS. However, the role of DAs in the clinical management of the different types of CS requires further evaluations.

The treatment with pasireotide in Cushing's disease: effect of long-term treatment on clinical picture and metabolic profile and management of adverse events in the experience of a single center.

PURPOSES: Pasireotide is the first medical therapy officially approved for adult patients with Cushing's disease (CD) experiencing failure of pituitary surgery or not candidates for surgery. The current study aimed at investigating pasireotide effects on clinical picture and metabolic profile in patients enrolled in the phase III CSOM230B2305 trial at Naples center. In addition, the current study focused on safety issues encountered during the study, detailing the management of the different adverse events associated with the treatment with pasireotide in Naples center. METHODS: Fourteen patients entered the study; eight patients, receiving pasireotide for at least 6 months, were considered for the efficacy analysis, whereas the entire cohort of 14 patients was considered for the safety analysis. RESULTS: Full or partial disease control was obtained in 85.7% of patients, according to a "per-protocol" methodology analysis, and in 42.9% of patients, according to an "intention-to-treat" methodology analysis, after 12 months of treatment. A relevant improvement in clinical signs and symptoms, mainly in facial rubor, supraclavicular fat pad, bruising, hirsutism, and muscle strength was observed; body weight, body mass index, and waist circumference significantly reduced, and a slight non-significant reduction was observed in the prevalence of visceral obesity, hypercholesterolemia, and hypertriglyceridemia. Deterioration of glucose metabolism represented the most common adverse event, occurring in 71.4% of patients, and requiring a dietary regimen as first step, metformin therapy and/or long-acting insulin as second step, and short-acting insulin, as third step; no patients discontinued treatment for hyperglycaemia. Additional adverse events of interest were nausea (21.4%), and vomiting (14.3%), spontaneously resolved in few weeks or some months, except in one patient unsuccessfully treated with metoclopramide and ondansetron, and diarrhoea (14.3%), improved with loperamide treatment. Millimetric gallstones and biliary sludge (7.1%) were managed with ursodeoxycholic acid, inducing lithiasis and biliary sludge resolution, whereas hypocortisolism-related adverse events (7.1%) were resolved with a reduction in the pasireotide dose. CONCLUSIONS: The current study on a limited series of patients contributes to confirm that pasireotide may be considered a valid option for treatment of patients with CD, although it requires an appropriate management of adverse events, especially hyperglycaemia.

Chromogranin A, Ki-67 index and IGF-related genes in patients with neuroendocrine tumors.

Chromogranin A (CgA) and the Ki-67 proliferation index are considered as important biochemical and pathological markers for clinical behaviour of gastroenteropancreatic neuroendocrine tumors (GEP NETs), respectively. The IGF system has been suggested as an important regulator of GEP NET proliferation and differentiation. A possible relationship between serum CgA (sCgA), Ki-67 proliferation index, and expression of IGF-related genes in patients with GEP NETs has not been demonstrated yet. This study investigates the relationship between sCgA, the Ki-67 proliferation index, and the expression of IGF-related genes in GEP NET tissues and their relation with 5-year survival. Tumor and blood samples from 22 GEP NET patients were studied. TUMORAL MRNA EXPRESSION OF IGF-RELATED GENES (IGFS: IGF1, IGF2; IGF receptors: IGF1R, IGF2R; insulin receptors: subtype A (IR-A) and B (IR-B); IGF-binding proteins (IGFBPs): IGFBP1, IGFBP2, IGFBP3, and IGFBP6) was measured using quantitative RT-PCR. Ki-67 proliferation index was determined using immunohistochemistry. sCgA was measured with ELISA. Five-year survival in patients with nonelevated sCgA (n=11) was 91 vs 46% in patients with elevated sCgA (n=11) (P=0.006). IR-A mRNA expression was significantly higher in tumors obtained from patients with elevated sCgA than in those from patients with nonelevated sCgA (6.42±2.08 vs 2.60±0.40; P=0.04). This data suggests that sCgA correlates well with 5-year survival of GEP NET patients, and that IR-A mRNA expression correlates well with tumor mass in GEP NET patients.

Role of the mTOR pathway in normal and tumoral adrenal cells.

The mammalian target of rapamycin (mTOR) is a kinase of the phosphoinositide 3-kinase (PI3Ks)/protein kinase B (PKB or AKT) signaling pathway, which is one of the most important intracellular mediators of the activity of growth factors receptors, including vascular endothelial growth factor (VEGF) and insulin-like growth factors (IGFs). Dysregulation of the mTOR pathway has been found in many human tumors. Therefore, the mTOR pathway is considered as a target for antineoplastic therapy in several malignancies. Presently, the role and functions of mTOR and its signaling pathway in the normal and pathological adrenal gland has not been clarified yet. However, many growth factors and growth factor receptors, which are considered to play a role in the pathogenesis of adrenal tumors, can at least in part exert their effects through the activation of PI3K/AKT/mTOR pathway. Dysregulation of AKT has been reported in adrenocortical carcinomas and adrenomedullary tumors, named pheochromocytomas. Adrenocortical carcinomas and malignant pheochromocytomas are aggressive tumors with poor prognosis and scant treatment options. Therefore, new treatment options are warranted for these malignancies. On the basis of the current knowledge, mTOR could play a role in the pathogenesis of both adrenocortical carcinomas and pheochromocytomas. Moreover, mTOR inhibitors, interfering with the activation of several mitogenic and angiogenic factors, could be considered as a novel treatment opportunity for the management of malignant adrenal tumors.

The treatment with growth hormone receptor antagonist in acromegaly: effect on vascular structure and function in patients resistant to somatostatin analogues.

BACKGROUND: Acromegaly is known to be associated to vascular damage characterized by an increase of vascular wall thickness and an impairment of vascular function. AIM: The aim of this study was to evaluate the effect of medical treatment with the GH receptor antagonist pegvisomant on vascular structure and function in acromegalic patients resistant to somatostatin analogues. PATIENTS: Ten patients (4 males and 6 females, 28-58 yr) and 20 sex-, age-, and body mass index-matched healthy controls entered the study. All patients were treated for 18 months with pegvisomant at doses ranging from 10 to 40 mg/day. OUTCOME MEASURES: Primary outcome measures were measurement of carotid arteries intima-media thickness (IMT), and brachial arteries flow mediated dilation (FMD); secondary outcome measures were blood pressure, blood glucose and lipids levels. RESULTS: Carotid arteries maximal IMT was significantly higher in patients than in controls at baseline (1.18±0.59 vs 0.69±0.13, p=0.001) and slightly, but not significantly, decreased after treatment (0.97±0.17). Brachial arteries FMD was significantly lower in patients than controls at baseline (7.5±2.5 vs 13.1±1.4, p<0.001) and significantly increased after treatment (8.8±3.7, p=0.016). Systolic (SBP) and diastolic (DBP) blood pressure values, serum glucose and insulin levels and homeostasis model assessment (HOMA) index were higher, whereas HDL-cholesterol levels were lower in patients than controls at baseline. After treatment, SBP and DBP, as well as serum glucose and insulin levels and HOMA index significantly decreased whereas no significant change was found in serum lipid profile. CONCLUSIONS: The results of the current study suggested that long-term treatment with pegvisomant induced a slight reduction of carotid arteries wall thickness and a significant improvement of brachial arteries vascular function in patients with acromegaly resistant to somatostatin analogues.

Weekly clodronate treatment prevents bone loss and vertebral fractures in women with subclinical Cushing's syndrome.

INTRODUCTION: Chronic mild endogenous glucocorticoid excess has been shown to cause bone loss and to increase fracture risk in both post-menopausal and premenopausal women. Currently, it is unclear if patients with subclinical Cushing's syndrome (SCS) with osteoporosis or osteopenia may benefit from antiresorptive treatment and the type of therapy to be given. OBJECTIVE: This pilot randomized study was aimed at evaluating the effects of 12-month im administration of clodronate (100 mg every week) on vertebral and femoral bone mineral density (BMD), bone turnover markers and on subjective pain in premenopausal women with SCS due to adrenal incidentalomas. METHODS: Forty-six women (age, 43.1+/-7.7 yr) with SCS due to adrenal incidentaloma and osteoporosis/osteopenia were randomized to receive clodronate plus supplement of Calcium (500 mg daily) and Vitamin D3 (800 mg daily) (group 1, no.=23) or supplements only (group 2, no.=23). Both groups were similar in terms of age, body mass index, cortisol levels, BMD values, and bone turnover markers. All of the women were re-evaluated after 12 months. RESULTS: After 12 months of treatment, in group 1, a significant increase in lumbar BMD occurred (p=0.04), while bone turnover markers decreased by about one third (p<0.05). In group 2, bone turnover markers did not change and BMD values slightly decreased (p=ns). The differences in bone turnover markers and in lumbar BMD between the two groups were significant (p<0.05, all). No new vertebral fracture occurred in group 1, while in group 2 the spine radiographies revealed 2 new fractures and a worsening of two pre-existent fractures. An improvement in subjective back pain, assessed by visual analogue scale pain score was observed in group 1 (from 4.3+/-2.7 to 2.9+/-2.0; p<0.05) but not in group 2 (from 4.4+/-3.1 to 4.2+/-3.4; p=ns). No significant changes occurred in cortisol secretion or clinical picture of the SCS during the study. CONCLUSIONS: Intramuscular administration of clodronate effectively increased lumbar BMD values, preserved bone mass at the femoral neck, stabilized vertebral fracture index, and decreased subjective back pain in pre-menopausal women with SCS. Since the untreated group continued to lose bone, antiresorptive treatment should be considered in patients with SCS, according to the prevision of surgical treatment, prevalent fractures, BMD values, age, concomitant morbidities, and desire for pregnancy.

Octreotide-LAR vs lanreotide-SR as first-line therapy for acromegaly: a retrospective, comparative, head-to-head study.

No head-to-head comparisons are available to analyze the efficacy of octreotide (LAR) and lanreotide (LAN) as first-line treatment of acromegaly.We compared the efficacy of these two drugs in 54 newly diagnosed patients (21 women, 33 men), 27 treated with LAR (10-30 mg every 28 days) and 27 with LAN (60-90 mg/28 days), for 12 months. Each LAR-treated patient was matched with one LAN-treated patient as for GH levels, sex, and age (+/-5 yr). Outcome measures were GH and IGF-I levels and tumor shrinkage and secondarily classical cardiovascular risk factors (total/HDL-cholesterol ratio, glucose tolerance), blood pressure and drug tolerability. In LAR- and in LAN-treated patients, respectively: GH and IGF-I were controlled in 21 (77.7%) and in 16 patients (59.3%; p=0.26); tumor shrinkage was absent (<25%) in 4 and 5 patients (p=1), mild (25.1-50%) in 9 and 12 (p=0.57), moderate (50.1-75%) in 10 and 6 (p=0.37) and notable (>75%) in 4 and 4 patients (p=1). The total/HDL-cholesterol ratio and insulin levels significantly decreased while glucose levels significantly increased in both groups. None of the patients with normal glucose tolerance at diagnosis developed diabetes mellitus. Side effects were mostly at the gastrointestinal level and were similar with both drugs. In conclusion, newly diagnosed patients with acromegaly treated with LAR and LAN have no significantly different prevalence of disease control, tumor shrinkage, improvement of cardiovascular risk markers and side effects. Therefore, both drugs can be safely employed as first-line therapy of acromegaly.

Circulating insulin-like growth factor-I levels are correlated with the atherosclerotic profile in healthy subjects independently of age.

To investigate the relationships between the GH-IGF-I axis and the atherosclerotic profile, we designed this open, observational, prospective study. Peak GH after GHRH+arginine (ARG) test, serum IGF-I and IGF binding protein-3 (IGFBP-3), lipid profile, homeostasis model assessment (HOMA) index and intima-media thickness (IMT) at common carotid arteries were measured in 174 healthy individuals (92 women, 82 men, aged 18-80 yr). Exclusion criteria for this study were: 1) body mass index (BMI) > or = 30 kg/m2; 2) personal history of cardiovascular diseases; 3) previous or current treatments of diabetes or hypertension; 4) previous corticosteroids treatment for longer than 2 weeks or estrogens for longer than 3 months; 5) smoking of more than 15 cigarettes/day and alcohol abuse. Subjects were divided according to age in decade groups from < 20 to > 70 yr. BMI increased with age, as did systolic and diastolic blood pressures, although they remained in the normal range. The GH peak after GHRH+ARG test was significantly higher in the subjects aged < 20 yr than in all the other groups (p < 0.01), but was similar in the remaining groups. An inverse correlation was found between the IGF-I z-score and total/HDL-cholesterol ratio (p = 0.02) and mean IMT (p = 0.0009); IGFBP-3 z-score and mean IMT (p = 0.043); IGF: IGFBP-3 molar ratio and total/HDL-cholesterol ratio (p < 0.0001) and mean IMT (p < 0.0001). Atherosclerotic plaques were found in 7 out of 12 subjects (53.8%) with a z-IGF-I score from < or = -2 to -1, in 4 out of 63 (6.3%) with a z-IGF-I score from -0.99 to 0.1 out of 66 (1.5%) with a z-IGF-I score from 0.1 to 1 and none of the 33 subjects with an IGF-I z-score >1 (p = 0.006). At multi-step regression analysis, age was the best predictor of HDL-cholesterol levels and mean IMT, IGF-I level was the best predictor of total cholesterol and total/HDL-cholesterol ratio, the IGF-I/IGFBP-3 molar ratio was the best predictor of triglycerides levels. The z-scores of IGF-I and IGFBP-3 were the second best predictors of mean IMT after age. In conclusion, IGF-I and IGFBP-3 were negatively correlated with common cardiovascular risk factors, studied as total/HDL-cholesterol ratio, and/or early atherosclerosis, studied as IMT at common carotid arteries. The prevalence of atherosclerotic plaques, though not hemodinamically significant, was higher in the subjects having a z-score of IGF-I of < or = -2 to -1. Our results support a role of the IGF/IGFBP-3 axis in the pathogenesis of atherosclerosis.

Severe systemic complications of acromegaly.

It is well accepted that mortality in acromegaly is increased because of cardiovascular and respiratory diseases while neoplastic complications account less to mortality. Amongst different cardiovascular complications the most frequent is biventricular hypertrophy, which occurs independently of hypertension and metabolic complications that, in turn, aggravate the cardiomyopathy. Diastolic and systolic dysfunction develops in a variable number of patients, depending on age and disease duration. Other cardiac disorders, such as arrhythmias, valve disease, hypertension, atherosclerosis and endothelial dysfunction have been less characterized but all appear to be present in acromegaly, depicting the so called "acromegalic cardiomyopathy". The best characterized respiratory disease is the sleep apnea. Ventilatory dysfunction recognizes bony changes of thoracic cage and lung overgrowth as relevant pathogenetic factors. Earlier evidences that patients with acromegaly have an increased risk of developing malignancies have become more realistic in recent years. Most studies have reported an increased risk of colonic polyps, which more frequently recur in patients not controlled after treatment. Malignancies in other organs have also been described, but less convincingly than at the gastrointestinal level and are not a main cause of mortality. Bone changes are also feature of the disease. They involve theoretically all bones and, particularly, the appendicular and the axial skeleton. Patients with long-standing disease are more prone to develop degenerative changes. Control of acromegaly by surgery or pharmacotherapy, especially by somatostatin analogs, improves cardiovascular morbidity and sleep apnea. There is still no demonstration that improvement of different complications corresponds a reduction in mortality.

The role of somatostatin receptors in the medical treatment of acromegaly.

Somatostatin is a hypothalamic inhibitor of pituitary growth hormone secretion and cell proliferation, binding to five distinct receptor subtypes (sstr1-5). Since native somatostatin has a short half-life, somatostatin analogues with a longer half-life have been developed for therapeutic purposes. Octreotide and lanreotide are currently available for treatment of acromegaly, binding with high-affinity sstr2 and sstr5. Octreotide, the first somatostatin analogue used in the medical therapy of acromegaly, was initially given subcutaneously at doses of 100-500 microg three times daily. The introduction of new depot formulations, such as octreotide long-acting release, slow-release lanreotide and lanreotide-autogel, improved patients compliance of long-term therapy, overcoming the inconvenience of multiple daily administration. The treatment with somatostatin analogues induces biochemical control and tumour shrinkage in about 50-70% and 30-60% of patients with acromegaly, respectively. However, the efficacy of this therapy lies on an adequate expression of sstr2 and sstr5 on tumor cells. In the past, somatostatin receptor expression was tested in vivo by (111)In-diethylenetriaminepentaacetate-D-Phe-octreotide scintigraphy: this method has been abandoned since normal pituitary tissue can be visualised by (111)In-diethylenetriaminepentaacetate-D-Phe-octreotide scintigraphy. Currently, the somatostatin receptorial profile can be characterised by autoradiography, molecular biology techniques and immunohistochemistry on surgically removed tumor tissue. These methods may offer an individualised approach sparing patients from unnecessary treatment.

An evaluation of patients with hyperprolactinemia: have dynamic tests had their day?

Except for a few particular conditions, the diagnostic evaluation of hyperprolactinemia is easy since the routine use of magnetic resonance imaging (MRI) scan has permitted to identify even small microadenomas. Other conditions include the identification of large PRL molecular complex, dimers, trimers or polymers of PRL, called "big or big-big PRL", and of PRL autoantibodies and the biochemical finding of "high dose PRL hook effect". Finding elevated serum PRL levels should be considered as the beginning and not the conclusion of a diagnostic evaluation: first, a careful anamnesis should exclude possible physiologic, pharmacologic and organic causes of hyperprolactinemia; second, possibly one laboratory only, undergoing regularly quality controls, should analyze blood samples; serial serum PRL measurements at 0, 30, 60 min is a valuable and simple measure to identify stress-related hyperprolactinemia. In the past two decades several pharmacological tests were used in order to distinguish between small microprolactinomas and "non-tumoral hyperprolactinemia": the controversial results of these tests together with the availability of MRI has excluded all pharmacological tests in the work-up of hyperprolactinemia. MRI is preferred to computed tomography (CT) due to its better definition of very small lesions in the pituitary sella and better anatomical definition prior to surgery. Finally, once the diagnosis of prolactinoma is suspected, patients should be referred to a specialist centre for further assessment and treatment.

The use of a GH receptor antagonist in patients with acromegaly resistant to somatostatin analogs.

Pegvisomant, a GH receptor antagonist, is a new pharmaceutical approach to acromegaly. It enables IGF-I levels to return in the age- and sex-reference range in approximately 90% of patients. This new approach is particularly beneficial in those patients who do not experience control of hormone hypersecretion after surgery and/or medical treatment with somatostatin analogs. In our preliminary experience, out of 16 patients unsuccessfully operated on by transsphenoidal surgery and resistant to 40-mg octreotide-LAR or 120-mg lanreotide for at least 6 months, 13 normalized their IGF-I levels within 6 months from treatment beginning. Normalization of IGF-I levels was accompanied by a significant decrease of ring size. We did not observe any increase of tumor remnant in this short period of treatment. In two cases we observed a significant increase of liver transaminases levels. In conclusion, more than 80% of patients with acromegaly unsuccessfully treated by surgery or currently available somatostatin analogs can achieve normal IGF-I levels after short-term treatment with pegvisomant.

Age-related changes in the antinociception induced by taurine in mice.

Taurine is a nonessential amino acid that is of medical interest for the nutrition of infants. Taurine has been found in the central nervous system of rodents and humans, and among its potential therapeutic uses, it is interesting to remark its analgesic actions. It is also well known that concentration levels during the fetal and prenatal periods are higher than in adulthood. The data obtained so far indicate that taurine is involved in the development process of the brain and possibly other organs. The taurine levels in old age are still unknown, but it is presumed that they will be different from those of younger animals. Data about age-related alterations and functional modifications of this and other amino acids are still scarce. The aim of the present work was to study the antinociceptive effect of taurine and its relationship with aging in mice. No differences were found between prepubertal and young adult animals; on the contrary, old animals showed significantly reduced sensitivity to the antinociception induced by taurine; in fact, at the tested doses, taurine did not induce antinociception in this group of mice. The mechanism underlying this effect has not been clarified because there are several mechanisms and neurotransmitter systems involved in the antinociception induced by taurine.

Hypothalamus-pituitary-adrenal axis in central diabetes insipidus: ACTH and cortisol responsiveness to CRH administration.

A strong relationship has been found between arginine-vasopressin (AVP) and hypothalamus-pituitary-adrenal axis in humans. The aim of the current study was to evaluate baseline and CRH-stimulated ACTH and F levels in patients with central diabetes insipidus (CDI), before and after replacement therapy with desamino-D-AVP (DDAVP). Twenty-five patients with CDI, and 25 sex- and age- and BMI-matched healthy subjects entered the study. A standard CRH test (measurement of plasma ACTH and serum F before and every 15 min for 2 h after the administration of 100 microg of human CRH) was performed in all subjects. In patients with CDI, CRH test were repeated after 1 week of DDAVP at standard doses. At study entry, ACTH and F levels were significantly higher in patients with CDI than in controls either at baseline (ACTH: 45.5+/-4.8 vs 18.5+/-3.3 ng/l, p<0.05; F: 375.1+/-55.7 vs 146.6+/-19.4 microg/l, p<0.05) or after CRH test considered as a peak (ACTH: 90.8+/-14.4 vs 42.5+/-7.4 ng/l, p<0.05; F: 501.6+/-65.7 vs 226.3+/- 25.6 microg/l, p<0.05) and AUC (ACTH: 3997.0+/-571.7 vs 2136.0+/-365.8 ng/l/120 min, p<0.05; F: 31,489.0+/-4299.4 vs 14,854.5+/-1541.5 microg/l/120 min, p<0.05). In patients with CDI, 1 week of replacement with DDAVP brought down ACTH (peak: 56.9+/-9.3 ng/l; AUC: 2390.7+/-480.7 ng/l/120 min) and F (peak: 310.3+/-39.5 microg/l; AUC: 17,555.5+/-2008.7 microg/l/120 min) responses to CRH to normal but did not significantly modify baseline hormone levels (ACTH: 29.6+/-3.6 ng/l; F: 239.0+/-32.3 microg/l). In conclusion, CDI is associated to increased baseline ACTH and F levels and increased responsiveness of ACTH and F to CRH administration. In addition, replacement treatment with DDAVP normalized CRH-induced but not baseline ACTH and F secretion.

Role of K+ -channels in homotaurine-induced analgesia.

In previous articles, antinociceptive activity for homotaurine has been demonstrated to be mediated by opioid, GABAergic and cholinergic mechanisms. GABAB-agonists affect K+-channels and it is known that K+-channels modulate specific activation of opioid receptors. In this study, we examined the involvement of K+-channels in the antinociceptive activity of homotaurine (22-445 mg/kg). Antinociceptive response was obtained after icv pretreatment with the channel specific blockers 4-aminopyridine (voltage-dependent channels), tetraethylammonium (Ca++ and voltage-dependent) and gliquidone (ATP-dependent). The nociceptive tests performed were acetic acid induced abdominal constriction (mice) and tail flick (rats) tests. Acetic acid responses to homotaurine were inhibited by tetraethylammonium (5 microg) and gliquidone (16 microg). Tail flick response to homotaurine was inhibited by tetraethylammonium (50 microg), gliquidone (40 and 80 microg) and 4-aminopyridine (25 and 250 ng). These results suggest an involvement of the three types of K+-channels in antinociception by homotaurine, depending on specific homotaurine and blocker doses. At a spinal level, they appear to be involved together with GABAB and opioid mechanisms. Peripherally, only tetraethylammonium channels would be substantially activated during homotaurine antinociceptive effect.

Helicobacter pylori pore-forming cytolysin orthologue TlyA possesses in vitro hemolytic activity and has a role in colonization of the gastric mucosa.

Hemolysins have been found to possess a variety of functions in bacteria, including a role in virulence. Helicobacter pylori demonstrates hemolytic activity when cultured on unlysed blood agar plates which is increased under iron-limiting conditions. However, the role of an H. pylori hemolysin in virulence is unclear. Scrutiny of the H. pylori 26695 genome sequence suggests the presence of at least two distinct hemolysins, HP1086 and HP1490, in this strain. Previous studies have shown that the in vitro hemolytic activity of H. pylori is reduced when it is coincubated with dextran 5000, suggesting the presence of a pore-forming cytolysin. HP1086 has homology to pore-forming cytolysins (TlyA) from other bacterial species, and the introduction of the cloned H. pylori tlyA gene into a nonhemolytic Escherichia coli strain conferred hemolytic activity. An H. pylori tlyA defined mutant showed reduced in vitro hemolytic activity, which appears to be due to pore formation, as the hemolytic activity of the wild-type strain is reduced to the same level as the tlyA mutant by the addition of dextran 5000. The mutant also showed reduced adhesion to human gastric adenocarcinoma cells and failed to colonize the gastric mucosa of mice. These data clearly suggest a role in virulence for H. pylori TlyA, contrary to the suggestion that hemolytic activity is an in vitro phenomenon for this pathogen.

[New therapeutic strategies in gastroenteropancreatic neuroendocrine tumours]. / Nuovo strategie terapeutiche nei tumori neuroendocrini gastroenteropancreatici.

Neuroendocrine tumours are frequently malignant and have often reached an advanced stage by the time of diagnosis when they are inoperable, accompanied by severe symptoms, sometimes of an endocrine nature. Current therapeutic procedures include surgery, embolisation of hepatic metastases, local radiotherapy, biotherapy and chemotherapy. Over the years somatostatin analogs, of which octreotide is the first form, have become increasingly important in the treatment of patients with neuroendocrine tumours. A major step forward in analog treatment is represented by the development of slow-release formulas which do not require multiple daily injections and reduce the onset of resistance. The treatment of neuroendocrine tumours in the future will be based on the increased use of somatostatin analogs alone or in association with interferon or chemotherapy, and will also include surgery, radiometabolic therapy and targeted irradiation of the tumour.

Phase variation in H type I and Lewis a epitopes of Helicobacter pylori lipopolysaccharide.

Helicobacter pylori NCTC 11637 lipopolysaccharide (LPS) expresses the human blood group antigens Lewis x (Le(x)), Le(y), and H type I. In this report, we demonstrate that the H type I epitope displays high-frequency phase variation. One variant expressed Le(x) and Le(y) and no H type I as determined by serology; this switch was reversible. Insertional mutagenesis in NCTC 11637 of JHP563 (a poly(C) tract containing an open reading frame homologous to glycosyltransferases) yielded a transformant with a serotype similar to the phase variant. Structural analysis of the NCTC 11637 LPS confirmed the loss of the H type I epitope. Sequencing of JHP563 in strains NCTC 11637, an H type I-negative variant, and an H type I-positive switchback variant showed a C14 (gene on), C13 (gene off), and C14 tract, respectively. Inactivation of strain G27, which expresses Le(x), Le(y), H type I, and Le(a), yielded a transformant that expressed Le(x) and Le(y). We conclude that JHP563 encodes a beta3-galactosyltransferase involved in the biosynthesis of H type I and Le(a) and that phase variation in H type I is due to C-tract changes in this gene. A second H type I-negative variant (variant 3a) expressed Le(x) and Le(a) and had lost both H type I and Le(y) expression. Inactivation of HP093-HP094 resulted in a transformant expressing Le(x) and lacking Le(y) and H type I. Structural analysis of a mutant LPS confirmed the serological data. We conclude that the HP093-HP094 alpha2-fucosyltransferase (alpha2-FucT) gene product is involved in the biosynthesis of both Le(y) and Le(x). Finally, we inactivated HP0379 in strain 3a. The transformant had lost both Le(x) and Le(a) expression, which demonstrates that the HP0379 gene product is both an alpha3- and an alpha4-FucT. Our data provide understanding at the molecular level of how H. pylori is able to diversify in the host, a requirement likely essential for successful colonization and transmission.