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Biomedical subjects

G Galli

Publications and source records attributed to G Galli.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of the functional and growth properties of long-term cell cultures established from a human somatostatinoma.

In somatostatinoma, a rare malignant somatostatin (SST)-secreting neoplasia, tumour regression is rarely observed, implying the need for novel antiproliferative strategies. Here, we characterized a long-term culture (SST-secreting cancer (SS-C cells)) established from a human somatostatinoma. High concentrations of SST and chromogranin A were released by SS-C cells and SST release was stimulated by depolarizing stimuli and inhibited by the SST analogue, octreotide. SS-C cells expressed mRNA for SST receptor (SSTR) subtypes 1, 2 and 4, being also able to bind native SST. Moreover, SS-C cells were positively stained with an antibody to SSTR2. SS-C cells also expressed interferon-gamma (IFN-gamma) receptor mRNA and measurable telomerase activity. Our findings indicate that in vitro exposure of SS-C cells to native SST-28, to octreotide, to IFN-gamma, or to 3'-azido-3'deoxythymidine (AZT), a telomerase inhibitor, results in inhibition of SS-C cell proliferation. Concomitant with growth inhibition, apoptosis was detected in SST-, octreotide-, IFN-gamma- or AZT-treated SS-C cell cultures. Taken together our results characterized native SST, SST analogues, IFN-gamma and a telomerase inhibitor as growth-inhibiting and proapoptotic stimuli in cultured human somatostatinoma cells. Based on these findings, the potential of SST analogues, IFN-gamma and AZT, alone or in combination, should be further explored in the medical treatment of somatostatinoma.

Adult↗
PubMed2005

[Superior mesenteric artery syndrome: a cause of vomiting in children. Report of 3 cases].

Duodenal obstruction by Superior Mesenteric Artery (SMA) is a misdiagnosed vomiting syndrome in children. Several factors are involved, including rapid weight loss, rapid statural growth without weight augmentation. Diagnosis is suspected when an improvement is achieved by ventral decubitus and it is confirmed by plain films of the abdomen, GI study with barium and echography, measuring the aortomesenteric angle (inferior to 25-30 degrees ). Patients must at first be treated conservatively. Surgery is indicated for occlusive episodes with unsuccessful conservative therapy. The authors report 3 cases with different clinical presentation. However, all the patients presented important weight loss and vomiting.

Adolescent↗
PubMed2005

Spinal intradural extramedullary haemangioma: MRI and neurosurgical findings.

Haemangiomas, have rarely been encountered in the spinal intradural extramedullary space and the MRI findings of this entity have been described only in a few cases. We present the Magnetic Resonance Imaging (MRI) and surgical findings of a rare case of intradural extramedullary cavernous angioma located at the T1-T2 level in a 65-year-old man presented progressive paraparesis and upper thoracic back pain. On MRI, a well-circumscribed intradural solid mass, 1 cm in diameter, was detected and another enhancing nodular mass was found at the nerve roots of the cauda equina. The thoracic spinal lesion was removed and the histological diagnosis confirmed cavernous haemangioma. Although very uncommon, haemangioma should be included in the differential diagnosis when a spinal intradural extramedullary lesion is discovered and some neuroradiological findings could allow a presumptive diagnosis.

Aged↗
PubMed2005

Electron emission from diamondoids: a diffusion quantum Monte Carlo study.

We present density-functional theory (DFT) and quantum Monte Carlo (QMC) calculations designed to resolve experimental and theoretical controversies over the optical properties of H-terminated C nanoparticles (diamondoids). The QMC results follow the trends of well-converged plane-wave DFT calculations for the size dependence of the optical gap, but they predict gaps that are 1-2 eV higher. They confirm that quantum confinement effects disappear in diamondoids larger than 1 nm, which have gaps below that of bulk diamond. Our QMC calculations predict a small exciton binding energy and a negative electron affinity (NEA) for diamondoids up to 1 nm, resulting from the delocalized nature of the lowest unoccupied molecular orbital. The NEA suggests a range of possible applications of diamondoids as low-voltage electron emitters.

Journal Article↗
PubMed2004

LXR (liver X receptor) and HNF-4 (hepatocyte nuclear factor-4): key regulators in reverse cholesterol transport.

Cholesterol homoeostasis is the result of the fine tuning between intake and disposal of this molecule. High levels of cholesterol in the blood are detrimental as they may lead to excessive accumulation in vessel walls, a condition predisposing to the development of atherosclerotic lesions. Cholesterol is removed from the vessel wall and transported to the liver through a process called reverse cholesterol transport. Nuclear receptors are among the most important transcription factors regulating genes involved in different steps of reverse cholesterol transport. Here, we discuss the role of the nuclear receptors LXR (liver X receptor) and HNF-4alpha (hepatocyte nuclear factor-4alpha) in different steps of reverse cholesterol transport. LXR controls the transcription of crucial genes in cholesterol efflux from macrophages and its transport to the liver, such as ABCA1 (ATP binding cassette A1), CYP27A1 (sterol 27-hydroxylase), CLA-1 (scavenger receptor type B1) and apolipoprotein E. Some oxysterols present in oxidized low-density lipoproteins and proinflammatory cytokines modulate the activity of LXR by antagonizing the effect of activators of this receptor, thus contributing to cholesterol accumulation in macrophages. Bile acid synthesis, which represents the final step of reverse cholesterol transport, is transcriptionally regulated by several nuclear receptors at the level of the liver-specific cytochrome P450 cholesterol 7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme of this metabolic pathway. Bile acids returning to the liver through the enterohepatic circulation down-regulate CYP7A1 transcription via the bile acid sensors farnesoid X receptor and HNF-4alpha. Based on this evidence, these nuclear receptors are candidate targets of new drugs for the treatment and prevention of atherosclerotic disease.

Animals↗
PubMed2004

Analysis by high-performance liquid chromatography of teucrin A in beverages flavoured with an extract of Teucrium chamaedrys L.

Due to its liver toxicity, the medicinal use of germander (Teucrium chamaedrys L.) was banned in some countries. Nevertheless, alcoholic extracts are still permitted as flavour ingredients since they are fundamental in providing a bitter aromatic taste. Teucrin A represents the substance of major concern regarding the potential toxicity of germander. Hence, teucrin A represents the best analytical and toxicological marker of alcoholic extracts of T. chamaedrys. A sensitive high-performance liquid chromatography method to detect teucrin A in beverages is reported. Teucrin A was prepared by isolation from the plant extract using column chromatography and crystallization. The identity and purity (99%) were established by melting point, nuclear magnetic resonance and liquid chromatography-mass spectrometry. The high-performance liquid chromatography procedure was validated and its intra- and interday performance was established (relative standard deviation < or = 13% and error < or = 10%). In-house validation was carried out by analysing samples of beverages not containing T. chamaedrys spiked with a range of concentrations of teucrin A. The limit of detection was 0.1 ppm and the limit of quantification was 0.3 ppm. Teucrin A accounted for about 70% of the neo-clerodane diterpenoids found in the total extract of a specimen of T. chamaedrys. The content (+/- standard deviation) in 18 batches of different geographical origin was 2338 +/- 740 ppm, per cent coefficient of variation = 32, minimum-maximum = 999 - 3445 ppm. The mean level of teucrin A in 10 bottles of the same brand was 6.1 +/- 0.8 ppm, per cent coefficient of variation = 12. In 10 different brands found on the Italian market, the content of teucrin A ranged from not detectable to 10 ppm.

Alcoholic Beverages↗
PubMed2003

High-pressure molecular phases of solid carbon dioxide.

We present a theoretical study of solid CO2 up to 50 GPa and 1500 K using first-principles calculations. In this pressure-temperature range, interpretations of recent experiments have suggested the existence of CO2 phases which are intermediate between molecular and covalent-bonded solids. We reexamine the concept of intermediate phases in the CO2 phase diagram and propose instead molecular structures, which provide an excellent agreement with measurements.

Journal Article↗
PubMed2002

Sputum processing: a new method to improve cytospin quality.

BACKGROUND: Sputum examination is being increasingly used as a non-invasive method for studying airway inflammation. However, the application of sputum still presents some methodological problems and the results of sputum analysis may be substantially flawed by salivary contamination, cell and mucus debris. In addition, much work is needed to deepen the possibility of extensive application of cell and molecular biology techniques to sputum analysis. OBJECTIVE: In an attempt to improve the technique of sputum processing, we investigated the effect of: (i) 20 and 11 microm filtration in addition to 40 microm on salivary contamination; (ii) Percoll density gradient centrifugation on sputum slides quality; (iii) a culture medium (Minimum Essential Medium containing HEPES 22 mm, pH 7.4: MEM) as washing and suspension solution compared to PBS on cell viability. METHODS: Induced sputum samples were obtained in 37 asthmatics. 21 samples were processed as selected sputum and 16 samples as entire expectorates. After dithiotreitol (DTT) homogenization, each specimen was aliquoted in two parts of equal volume. One portion was processed with the usual method, the other using a modified method: cell pellet was suspended in sterile MEM, filtered through 40, 20 and 11 microm net filters and separated from the residual debris by Percoll gradient centrifugation. RESULTS: As compared to the current sputum processing this method resulted in: (i) no selective bronchial cellular loss; (ii) a significant decrease of salivary contamination, particularly in entire expectorates in which squamous cells were reduced from 47 (36) to 15.5% (20) as median values and interquartile range; (iii) a higher proportion of good quality cytospins; (iv) maintenance of cell viability over the time (88% vs. 81% in MEM and PBS, respectively) 1 h after sample collection. CONCLUSION: In the present study we demonstrated that the proposed method is feasible and makes it possible to overcome most of the technical limits met with the commonly used method, pointing to a potential extension of induced sputum application for more sophisticated techniques.

Adolescent↗
PubMed2001

Dissociation of water under pressure.

The dissociation of water under pressure is investigated with a series of ab initio molecular dynamics simulations at thermodynamic conditions close to those obtained in shock wave experiments. We find that molecular dissociation occurs via a bimolecular process similar to ambient conditions, leading to the formation of short-lived hydronium ions. Up to twofold compression and 2000 K, the oxygen diffusion coefficient is characteristic of a fluid. Our findings do not support models used to estimate the liquid electrical conductivity and interpret Raman spectra that assume the presence of free protons.

Journal Article↗
PubMed2001

The negative effects of bile acids and tumor necrosis factor-alpha on the transcription of cholesterol 7alpha-hydroxylase gene (CYP7A1) converge to hepatic nuclear factor-4: a novel mechanism of feedback regulation of bile acid synthesis mediated by nuclear receptors.

Bile acids regulate the cholesterol 7alpha-hydroxylase gene (CYP7A1), which encodes the rate-limiting enzyme in the classical pathway of bile acid synthesis. Here we report a novel mechanism whereby bile acid feedback regulates CYP7A1 transcription through the nuclear receptor hepatocyte nuclear factor-4 (HNF-4), which binds to the bile acid response element (BARE) at nt -149/-118 relative to the transcription start site. Using transient transfection assays of HepG2 cells with Gal4-HNF-4 fusion proteins, we show that chenodeoxycholic acid (CDCA) dampened the transactivation potential of HNF-4. Overexpression of a constitutive active form of MEKK1, an upstream mitogen-activated protein kinase (MAPK) module triggered by stress signals, strongly repressed the promoter activity of CYP7A1 via the consensus sequence for HNF-4 embedded in the BARE. Similarly, MEKK1 inhibited the activity of HNF-4 in the Gal4-based assay. The involvement of the MEKK1-dependent pathway in the bile acid-mediated repression of CYP7A1 was confirmed by co-transfecting a dominant negative form of the stress-activated protein kinase kinase, SEK, which abolished the effect of CDCA upon CYP7A1 transcription. Treatment of transfected HepG2 cells with tumor necrosis factor alpha (TNF-alpha), an activator of the MEKK1 pathway, led to the repression of CYP7A1 via the HNF-4 site in the BARE. TNF-alpha also inhibited the transactivation potential of HNF-4. Collectively, our results demonstrate for the first time that HNF-4, in combination with a MAPK signaling pathway, acts as a bile acid sensor in the liver. Furthermore, the effects of CDCA and TNF-alpha converge to HNF-4, which binds to the BARE of CYP7A1, suggesting a link between the cascades elicited by bile acids and pro-inflammatory stimuli in the liver.

Basic Helix-Loop-Helix Leucine Zipper Transcriptio↗
PubMed2001

Interferon-inducible protein 10, monokine induced by interferon gamma, and interferon-inducible T-cell alpha chemoattractant are produced by thymic epithelial cells and attract T-cell receptor (TCR) alphabeta+ CD8+ single-positive T cells, TCRgammadelta+ T cells, and natural killer-type cells in human thymus.

Strong reactivity for interferon-inducible protein 10 (IP-10), monokine induced by interferon gamma (Mig), and interferon-inducible T-cell alpha chemoattractant (I-TAC) was found in epithelial cells mainly localized to the medulla of postnatal human thymus. The CXC chemokine receptor common to the 3 chemokines (CXCR3) was also preferentially expressed in medullary areas of the same thymuses and appeared to be a property of 4 distinct populations: CD3+ T-cell receptor (TCR) alphabeta+ CD8+ single-positive (SP) T cells, TCRgammadelta+ T cells, natural killer (NK)-type cells, and a small subset of CD3+(low) CD4+ CD8+ TCRalphabeta+ double-positive (DP) T cells. IP-10, Mig, and I-TAC showed chemoattractant activity for TCRalphabeta+ CD8+ SP T cells, TCRgammadelta+ T cells, and NK-type cells, suggesting their role in the migration of different subsets of mature thymocytes during human thymus lymphopoiesis.

CD8-Positive T-Lymphocytes↗
PubMed2001

CD81 extracellular domain 3D structure: insight into the tetraspanin superfamily structural motifs.

Human CD81, a known receptor for hepatitis C virus envelope E2 glycoprotein, is a transmembrane protein belonging to the tetraspanin family. The crystal structure of human CD81 large extracellular domain is reported here at 1.6 A resolution. Each subunit within the homodimeric protein displays a mushroom-like structure, composed of five alpha-helices arranged in 'stalk' and 'head' subdomains. Residues known to be involved in virus binding can be mapped onto the head subdomain, providing a basis for the design of antiviral drugs and vaccines. Sequence analysis of 160 tetraspanins indicates that key structural features and the new protein fold observed in the CD81 large extracellular domain are conserved within the family. On these bases, it is proposed that tetraspanins may assemble at the cell surface into homo- and/or hetero-dimers through a conserved hydrophobic interface located in the stalk subdomain, while interacting with other liganding proteins, including hepatitis C virus E2, through the head subdomain. The topology of such interactions provides a rationale for the assembly of the so-called tetraspan-web.

Amino Acid Sequence↗
PubMed2001

Urinary excretion of olive oil phenols and their metabolites in humans.

We have recently demonstrated, in humans, the bioavailability of hydroxytyrosol (3,4-dihydroxyphenylethanol; HT), one of the major antioxidant components of virgin olive oil. In particular, we reported that this compound is present in lipoproteins involved in atherosclerotic processes and is excreted in the urine mainly as glucuronide-conjugate. The aim of the present study was to elucidate, in humans, the metabolic fate of HT after ingestion of virgin olive oil. After administration of virgin olive oil, 24-hour urine collections of healthy volunteers were prepared for gas chromatography-mass spectrometry analyses in order to identify and quantify HT and its metabolites homovanillic alcohol (HVA1c) and homovanillic acid (HVA). The results indicate that this compound undergoes the action of catechol-O-methyl transferase (COMT), enzymes involved in the catecholamine catabolism, resulting in an enhanced excretion of HVA1c. We also found a significant increase of HVA, indicating an oxidation of the ethanolic residue of HT and/or of HVA1c in humans. The excretion of both metabolites significantly correlated with the dose of administered HT.

Biological Availability↗
PubMed2001

Hydroxytyrosol, as a component of olive mill waste water, is dose- dependently absorbed and increases the antioxidant capacity of rat plasma.

Hydroxytyrosol is the most potent phenolic antioxidant of olive oil and olive mill waste water (OMWW) and its biological activities have stimulated research on its potential role in cardiovascular protection. However, evidence of the absorption of OMWW phenolics and on their possible in vivo activity has, until now, never been provided. Three groups male Sprague-Dawley rats were administered 1, 5, or 10 mg/Kg of the OMWW extract, respectively, providing 41.4, 207, and 414 microg/Kg of hydroxytyrosol, respectively. Urine was collected for 24 h and the urinary levels of hydroxytyrosol were quantified by mass spectrometry. Hydroxytyrosol was dose-dependently (R(2) = 0.95) absorbed and excreted in the urines mostly as a glucuronide conjugate. Further, the administration of an hydroxytyrosol-rich OMWW extract (10 mg/kg) to the rats was also associated with an increase of their plasma antioxidant capacity. Future experiments will eventually further clarify its metabolic fate and its in vivo actions.

Animals↗
PubMed2001

Crystallization and preliminary crystallographic studies on the large extracellular domain of human CD81, a tetraspanin receptor for hepatitis C virus.

The large extracellular domain of CD81, a member of the tetraspanin family and a receptor protein for hepatitis C virus envelope E2 glycoprotein, has been expressed, purified and subsequently crystallized using the sitting-drop vapour-diffusion technique. Native diffraction data to 1.6 A resolution were obtained at the ID14 beamline of the European Synchrotron Radiation Facility from a flash-frozen crystal at 100 K. The crystals belong to space group P2(1), with unit-cell parameters a = 31.5, b = 77.2, c = 38.5 A, beta = 107.4 degrees, and are likely to contain two extracellular domains (2 x 99 residues) per asymmetric unit.

Antigens, CD↗
PubMed2001

Validation of a simple method for assessing sodium intake in dialysis patients.

It has been reported that sodium intake can be estimated in dialysis patients by the increment in the body sodium pool from the end of a dialysis session to the beginning of the following one. To verify the reliability of this method we compared the sodium intake, estimated by the interdialytic changes in plasma sodium concentration (C) and body water volume (V), to sodium removal during three consecutive sessions. For this purpose we investigated 9 nondiabetic patients, 5 females and 4 males, under chronic hemofiltration treatment. Sodium intake was estimated by the formula (C(pre) V(pre)) - (C(post) V(post)) using a flame photometer and electrical bioimpedance to determine the plasma sodium concentration and total body water, respectively. Sodium removal was calculated by the difference between sodium loss into the ultrafiltrate and sodium gain with the reinfusion fluid. The mean values of sodium intake calculated during the three intervals corresponded with the sodium losses measured during the three hemofiltration sessions in each patient (338+/-55 vs. 329+/-67 mEq; r = 0.92, p<0.0001). A direct relationship was also observed between sodium intake and both interdialytic body weight increase (r = 0.89, p< 0.0001) and fluid loss during the sessions (r = 0.88, p<0.0001). This data demonstrates that sodium intake can be properly estimated by the interdialytic changes in body water and plasma sodium concentrations. They also suggest that fluid intake may be influenced by sodium consumption and that sodium intake monitoring could be useful for the control of excessive interdialytic fluid gain.

Aged↗
PubMed2001

Cell cycle-dependent expression of CXC chemokine receptor 3 by endothelial cells mediates angiostatic activity.

Endothelial cell receptors for the angiostatic chemokines IFN-gamma-inducible protein of 10 kDa (IP-10) and monokine induced by IFN-gamma (Mig) have not yet been identified, and the mechanisms responsible for the effects of these chemokines on angiogenesis are still unclear. IP-10 and Mig share a common functional receptor on activated T lymphocytes, named CXC chemokine receptor 3 (CXCR3). Using in situ hybridization and immunohistochemistry, we show that CXCR3 is expressed by a small percentage of microvascular endothelial cells in several human normal and pathological tissues. Primary cultures of human microvascular endothelial cells (HMVECs) likewise express CXCR3, although this expression is limited to the S/G2-M phase of their cell cycle. Both IP-10 and Mig, as well as the IFN-gamma-inducible T-cell alpha chemoattractant (I-TAC), which all share high-affinity binding for CXCR3, block HMVEC proliferation in vitro, an effect that can be inhibited by an anti-CXCR3 antibody. These data provide definitive evidence of CXCR3 expression by HMVEC and open new avenues for therapeutic interventions in all conditions in which an angiostatic effect may be beneficial.

Angiogenesis Inhibitors↗