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Biomedical subjects

G Galli

Publications and source records attributed to G Galli.

At least 37 records · Page 2Linked to original sources
PubMed2000

Olive oils rich in natural catecholic phenols decrease isoprostane excretion in humans.

This study was undertaken to evaluate, in humans, the antioxidant activity of olive oil phenolics, namely hydroxytyrosol and oleuropein aglycone that share an orthodiphenolic (catecholic) structure. Human volunteers were administered olive oil samples containing increasing amounts of an olive oil phenolic extract that was characterized by gas-chromatography/mass spectrometry. The administration of phenol-rich oils was dose-dependently associated with a decreased urinary excretion of 8-iso-PGF(2alpha), a biomarker of oxidative stress. Also, a statistically significant negative correlation between homovanillyl alcohol (HValc, hydroxytyrosol's major metabolite, formed through the COMT system) and F(2)-isoprostanes excretion was found. Thus, the administration of oil samples with increasing, albeit low, concentrations of orthodiphenolic compounds, namely hydroxytyrosol and oleuropein aglycone, results in a dose-dependent reduction in the urinary excretion of 8-iso-PGF(2alpha). The statistically significant negative correlation between 8-iso-PGF(2alpha) and HValc urinary concentrations suggests that this metabolite better reflects the in vivo activities of hydroxytyrosol.

Adult↗
PubMed2000

Macrophage-derived chemokine and EBI1-ligand chemokine attract human thymocytes in different stage of development and are produced by distinct subsets of medullary epithelial cells: possible implications for negative selection.

The chemoattractant activity of macrophage-derived chemokine (MDC), EBI1-ligand chemokine (ELC), and secondary lymphoid tissue chemokine (SLC) on human thymocytes was analyzed. Both ELC and SLC caused the accumulation of CD4+CD8- or CD4-CD8+ CD45RA+ thymocytes showing high CD3 expression. By contrast, a remarkable proportion of MDC-responsive thymocytes were CD4+CD8+ cells exhibiting reduced levels of CD8 or CD4+CD8- cells showing CD3 and CD45R0, but not CD45RA. MDC-responsive thymocyte suspensions were enriched in cells expressing the MDC receptor, CCR4, selectively localized to the medulla, and in CD30+ cells, whereas ELC-responsive thymocytes never expressed CD30. Reactivity to both MDC and ELC was localized to cells of the medullary areas, but never in the cortex. Double immunostaining showed no reactivity for either MDC or ELC by T cells, macrophages, or mature dendritic cells, whereas many medullary epithelial cells were reactive to MDC or ELC. However, MDC reactivity was consistently localized to the outer wall of Hassal's corpuscles, whereas ELC reactivity was often found in cells surrounding medullary vessels, but not in Hassal's corpuscles. Moreover, while most MDC-producing cells also stained positive for CD30L, this molecule was never found on ELC-producing cells. We suggest therefore that CD30L-expressing MDC-producing medullary epithelial cells attract CCR4-expressing thymocytes, thus favoring the CD30/CD30L interaction, and therefore the apoptosis, of cells that are induced to express CD30 by autoantigen activation. By contrast, ELC production by CD30L-lacking medullary epithelial cells may induce the migration into periphery of mature thymocytes that have survived the process of negative selection.

Cell Differentiation↗
PubMed2000

Identification and characterization of cis-acting elements conferring insulin responsiveness on hamster cholesterol 7alpha-hydroxylase gene promoter.

Bile acid biosynthesis occurs primarily through a pathway initiated by the 7alpha-hydroxylation of cholesterol, catalysed by cholesterol 7alpha-hydroxylase (encoded by CYP7A1). Insulin down-regulates CYP7A1 transcription. The aim of our study was to characterize the sequences of hamster CYP7A1 promoter, mediating the response to insulin. We therefore performed transient transfection assays with CYP7A1 promoter/luciferase chimaeras mutated at putative response elements and studied protein-DNA interactions by means of gel electrophoresis mobility-shift assay. Here we show that two sequences confer insulin responsiveness on hamster CYP7A1 promoter: a canonical insulin response sequence TGTTTTG overlapping a binding site for hepatocyte nuclear factor 3 (HNF-3) (at nt -235 to -224) and a binding site for HNF-4 at nt -203 to -191. In particular we show that the hamster CYP7A1 insulin response sequence is part of a complex unit involved in specific interactions with multiple transcription factors such as members of the HNF-3 family; this region does not bind very strongly to HNF-3 and as a consequence partly contributes to the transactivation of the gene. Another sequence located at nt -138 to -128 binds to HNF-3 and is involved in the tissue-specific regulation of hamster CYP7A1. The sequence at nt -203 to -191 is not only essential for insulin effect but also has a major role in the liver-specific expression of CYP7A1; it is the target of HNF-4. Therefore the binding sites for liver-enriched factors, present in the hamster CYP7A1 proximal promoter in close vicinity and conserved between species, constitute a regulatory unit important for basal hepatic expression and tissue restriction of the action of hormones such as insulin.

Animals↗
PubMed2000

Water under pressure

Water under pressure is investigated by first principles molecular dynamics, with a focus on the changes in hydrogen bonding and the oxygen network in the nondissociative regime. At a pressure of 10 GPa and a temperature of 600 K, which is close to the freezing point, no appreciable molecular dissociation is observed in the simulations. However, the structure of water is substantially altered from that at ambient conditions. The liquid exhibits a much larger coordination of oxygen atoms, an essential weakening of hydrogen bonding, and sizable changes in the density of electronic states close to the Fermi level. Our results provide new structural data for direct comparison with future experiments.

Journal Article↗
PubMed2000

Olive oil phenolics are dose-dependently absorbed in humans.

Olive oil phenolic constituents have been shown, in vitro, to be endowed with potent biological activities including, but not limited to, an antioxidant action. To date, there is no information on the absorption and disposition of such compounds in humans. We report that olive oil phenolics, namely tyrosol and hydroxytyrosol, are dose-dependently absorbed in humans after ingestion and that they are excreted in the urine as glucuronide conjugates. Furthermore, an increase in the dose of phenolics administered increased the proportion of conjugation with glucuronide.

Adult↗
PubMed2000

Limited expression of R5-tropic HIV-1 in CCR5-positive type 1-polarized T cells explained by their ability to produce RANTES, MIP-1alpha, and MIP-1beta.

Human T helper (Th) cells (Th1- or Th2-oriented memory T cells as well as Th1- or Th2-polarized naive T cells) were infected in vitro with an R5-tropic HIV-1 strain (BaL) and assessed for their profile of cytokine production, CCR5 receptor expression, and HIV-1 p24 antigen (p24 Ag) production. Higher p24 Ag production was found in CCR5-negative Th2-like memory T cells than in CCR5-positive Th1-like memory T cells. By contrast, p24 Ag production was higher in Th1-polarized activated naive T cells in the first 4 days after infection. However, p24 Ag production in Th1-polarized T cells became comparable or even lower than the production in Th2-polarized populations later in infection or when the cells were infected with HIV-1BaL after secondary stimulation. The higher levels of p24 Ag production by Th1-polarized naive T cells soon after infection reflected a higher virus entry, as assessed by the single round infection assay using the HIV-chloramphenicol acetyl transferase (HIV-CAT) R5-tropic virus that contains the envelope protein of HIV-1 YU2 strain. The limitation of viral spread in the Th1-polarized populations, despite the initial higher level of T-cell entry of R5-tropic strains, was due to the ability of Th1 cells to produce greater amounts of beta-chemokines than Th2 cells. In fact, an inverse correlation was observed between Th1-polarized naive T cells and Th1-like memory-activated T cells in regards to p24 Ag production and the release of the following CCR5-binding chemokines: regulated on activation normal T expressed and secreted (RANTES), macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta. Moreover, infection with the HIV-1BaL strain of Th1-polarized T cells in the presence of a mixture of anti-RANTES, anti-MIP-1alpha, and anti-MIP-1beta neutralizing antibodies resulted in a significant increase of HIV-1 expression. These findings suggest that Th1-type responses may favor CD4(+) T-cell infection by R5-tropic HIV-1 strains, but HIV-1 spread in Th1 cells is limited by their ability to produce CCR5-binding chemokines. (Blood. 2000;95:1167-1174)

Adult↗
PubMed2000

Macrophage-derived chemokine production by activated human T cells in vitro and in vivo: preferential association with the production of type 2 cytokines.

Macrophage-derived chemokine (MDC), a potent chemoattractant for chronically activated Th2 lymphocytes, is constitutively expressed by dendritic cells, B cells, macrophages, and thymic medullary epithelial cells, whereas monocytes, NK cells, and T lymphocytes produce MDC only upon appropriate stimulation. In this study, we show in vitro MDC production also by activated T cells, which preferentially associate with the production of Th2 cytokines, IL-4, IL-5, and IL-6, and inversely correlate with the production of the Th1 cytokine, IFN-gamma. Moreover, high levels of MDC were detected in the sera of the great majority of subjects suffering from mycosis fungoides/Sézary syndrome or atopic dermatitis, which are considered as disorders characterized by the predominant expansion and activation of Th2 cells, respectively. By contrast, serum MDC levels in subjects with multiple sclerosis or Crohn's disease, which are characterized by a Th1 predominance, did not differ significantly from those of healthy controls. Finally, MDC expression was detected in the skin biopsy specimens of subjects with atopic dermatitis, where it was expressed by both dendritic cells and T lymphocytes. Taken together, these findings suggest that MDC production by activated T cells may occur both in vitro and in vivo, particularly in association with Th2 cytokines, thus providing an important amplification circuit for Th2-mediated responses.

Biopsy↗
PubMed2000

Dynamic magnetic resonance imaging in the assessment of chronic medical nephropathies with impaired renal function.

We examined the value of dynamic magnetic resonance imaging (MRI) in chronic renal disease with renal insufficiency. In 33 consecutive patients (21 vascular nephropathy, 12 glomerular nephropathy) MRI was performed using a 1.5-T unit and a body coil, with SE T1-weighted (TR/TE = 600/19 ms) and dynamic TFFE T1-weighted sequences (TR/TE = 12/5 ms, flip angle = 25 degrees ) after manual bolus injection (via a cubital vein) of 0.1 mmol/kg Gd-DTPA-BMA. Morphological evaluation was performed in unblinded fashion by three radiologists, evaluating renal size, cortical thickness, and corticomedullary differentiation. Functional analysis was performed by one reviewer. Time-signal intensity curves, peak intensity value (P), time to peak intensity (T), and the P/T ratio were obtained at the cortex, medulla, and pyelocaliceal system of each kidney. The relationship of these parameters to serum creatinine and with creatinine clearance was investigated. A good correlation between morphological features of the kidneys and serum creatinine values was found. Morphological findings could not distinguish between vascular and glomerular nephropathies. A statistically significant correlation (P <0.01) between cortical P, cortical P/T, medullary P, and serum creatinine and creatinine clearance was found. A significant correlation (P <0.01) was also found between cortical T, medullary P/T, T of the excretory system, and creatinine clearance. The cortical T value was significantly higher (P <0.01) in vascular nephropathy than in glomerular nephropathy. Thus in patients with chronic renal failure dynamic MRI shows both morphological and functional changes. Morphological changes are correlated with the degree of renal insufficiency and not with the type of nephropathy; the functional changes seem to differ in vascular from glomerular nephropathies.

Aged↗
PubMed2000

Animal models of addiction: models for therapeutic strategies?

When having a continuous free choice in their home cages between water and alcohol- or drug-containing drinking solutions, rats first develop a controlled consumption of the psychotropic compound and, after several months, lose their control over drug taking. After a long period of abstinence, they reveal an excessive, compulsive drug intake. Adulteration of the drug-containing solutions reduces the doses taken by controlled consumers, but not those of the excessive drinkers, they can therefore be regarded as addicted. These animals show a pre-intake motor restlessness that may be related to craving. In two studies with putative anti-craving agents (the dopamine D2 receptor agonist lisuride and the D2 receptor antagonist flupentixol) we treated alcohol-addicted and non-addicted rats and observed the effects on alcohol taking, alcohol seeking and brain neurotransmission. These two investigations paralleled clinical studies, in both cases the results could be predicted correctly ("pro-craving" effect of both pharmaceutics). Differences between "symptomatic" and possible "causal" therapies are discussed, approaches towards a causal therapy according to an "imprinting"-model of an addition are suggested.

Alcoholism↗
PubMed2000

Rapid evaluation of phenolic component profile and analysis of oleuropein aglycon in olive oil by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS).

Epidemiological studies have linked the Mediterranean diet with a low incidence of cardiovascular diseases. Olive oil, the major fat component of this diet, is characterized by antioxidant properties related to their content in catecholic components, particularly oleuropein aglycon. Therefore quantification of these components in edible oils may be important in determining the quality, and consequently its commercial value. The present method allows us to obtain the profile of the phenolic components of the oil from the methanolic extracts of the crude olive oil. In particular tyrosol, hydroxytyrosol, elenolic acid, deacetoxyligstroside and deacetoxyoleuropein aglycons, ligstroside and oleuropein aglycons, and 10-hydroxy-oleuropein are clearly identified by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). Moreover, oleuropein and its isomers present in the oil are quantified by APCI-MS/MS analysis of the extracts without preliminary separation from other phenolic compounds.

Dietary Fats, Unsaturated↗
PubMed2000

Enhanced expression of the CXCR4 co-receptor in HIV-1-infected individuals correlates with the emergence of syncytia-inducing strains.

The aim of this study was to investigate the mechanisms responsible for the emergence in some HIV-1-infected individuals of highly aggressive, syncytia-inducing (SI) HIV-1 strains, which have been shown to use CXCR4 as co-receptor to enter target cells. To this end, the percentages of circulating CXCR4+CD4+ T cells were evaluated by flow cytometry in 39 untreated and 61 highly active antiretroviral therapy (HAART)-treated HIV-1-infected individuals in comparison with 35 HIV-1 seronegative subjects. Plasma viremia was also measured, and HIV primary isolates, from both untreated and HAART-treated HIV-1-infected subjects, were tested for the presence of SI strains. The results of this study showed enhanced proportions of CXCR4+CD4+ T cells in untreated patients in comparison with HAART-treated and healthy subjects. Furthermore, the results of a 12-month longitudinal study in a cohort of 11 patients undergoing HAART showed a significant reduction of CXCR4 expression after successful therapy. Finally, a significant positive correlation among the proportions of circulating CXCR4-expressing CD4+ T cells, plasma viremia, and the probability to isolate SI strains was found. These in vivo data are in keeping with previous in vitro results suggesting a bidirectional link between HIV-1 and CXCR4 expression on CD4+ T cells, and provide some clues to understanding the mechanisms exerting a selective pressure toward the emergence of SI strains.

Adult↗
PubMed2000

Structure-function analysis of hepatitis C virus envelope-CD81 binding.

Hepatitis C virus (HCV) is a major human pathogen causing chronic liver disease. We have recently found that the large extracellular loop (LEL) of human CD81 binds HCV. This finding prompted us to assess the structure-function features of HCV-CD81 interaction by using recombinant E2 protein and a recombinant soluble form of CD81 LEL. We have found that HCV-E2 binds CD81 LEL with a K(d) of 1.8 nM; CD81 can mediate attachment of E2 on hepatocytes; engagement of CD81 mediates internalization of only 30% of CD81 molecules even after 12 h; and the four cysteines of CD81 LEL form two disulfide bridges, the integrity of which is necessary for CD81-HCV interaction. Altogether our data suggest that neutralizing antibodies aimed at interfering with HCV binding to human cells should have an affinity higher than 10(-9) M, that HCV binding to hepatocytes may not entirely depend on CD81, that CD81 is an attachment receptor with poor capacity to mediate virus entry, and that reducing environments do not favor CD81-HCV interaction. These studies provide a better understanding of the CD81-HCV interaction and should thus help to elucidate the viral life cycle and to develop new strategies aimed at interfering with HCV binding to human cells.

Amino Acid Sequence↗
PubMed2000

Evidence of postprandial absorption of olive oil phenols in humans.

BACKGROUND AND AIM: Olive oil phenols are potent antioxidants in vitro. If this were to be also demonstrated in vivo, it would help to explain the beneficial effects of this typical ingredient of the Mediterranean diet. This study was designed to determine the presence in lipoprotein fractions of two phenolic compounds peculiar to extra virgin olive oil, namely tyrosol and OH-tyrosol, and whether their absorption induces an antioxidant effect in vivo. METHODS AND RESULTS: Two trials were performed. In the first (Long-term), 14 healthy volunteers followed two diets, each for one month. The only difference between the diets was that the first supplied 50 g of extra virgin olive oil per day, where-as the second one supplied 50 g of refined olive oil with no simple phenols, as demonstrated by GC-MS analysis. There were no changes in LDL oxidizability and tyrosol and OH-tyrosol were not recovered in lipoproteins and plasma from fasting samples drawn at the end of each diet period. In the second study (Postprandial), eight healthy volunteers received an oral fat load consisting of 100 g of extra virgin olive oil. Blood was drawn at times 0', 30', 60', 120', 240', 360', and major plasma lipoprotein classes were separated. The concentration of tyrosol, OH-tyrosol and vitamin E was determined in lipoprotein fractions. Plasma antioxidant capacity was measured by a crocin-bleaching test and expressed as mM Trolox C equivalents. Tyrosol and OH-tyrosol were recovered in all lipoprotein fractions, except VLDL, with concentrations peaking between 60' and 120'. However, a very high variability in tyrosol and OH-tyrosol absorption was observed among subjects. Vitamin E content of LDL and HDL did not vary significantly throughout the study. Plasma antioxidant capacity increased significantly at time 120' (baseline 0.96 mM Trolox; 120' 1.19 mM Trolox; p = 0.02), and then returned almost to baseline values after 360' (1.1 mM Trolox). CONCLUSIONS: These findings suggest that phenolic compounds in olive oil are absorbed from the intestine, though not through a pathway dependent on chylomicron formation, and may exert a significant antioxidant effect in vivo, probably in the postprandial phase.

Adolescent↗
PubMed1999

Oxysterols from oxidized LDL are cytotoxic but fail to induce hsp70 expression in endothelial cells.

Oxidized low density lipoprotein (OxLDL) possesses several proatherogenic characteristics, among which a marked cytotoxicity. In vitro, cytotoxicity of OxLDL to endothelial cells is associated with an increase in the expression of the inducible form of heat shock protein 70 (hsp70), generally regarded as a cytoprotective protein. Oxidized derivatives of cholesterol which form upon LDL oxidation are cytotoxic. Moreover, most of the OxLDL cytotoxicity is due to its lipid moiety, in particular to oxysterols. In this report we demonstrate that although oxysterols identified in OxLDL are cytotoxic, they cannot trigger the increase in hsp70 expression observed with intact oxidized lipoproteins. We speculate therefore that oxysterols may represent the most toxic form of oxidized lipids in LDL because they cannot activate a rescue mechanism (i.e. the hsp response) and may contribute significantly to cell death within atherosclerotic plaques.

Apoptosis↗
PubMed1999

Assessment of chemokine receptor expression by human Th1 and Th2 cells in vitro and in vivo.

The preferential association of some chemokine receptors with human Th1 or Th2 cells has recently been reported. In this study, the expression of CCR3, CCR5, CXCR3, and CXCR4 were analyzed by flow cytometry in three distinct in vitro models of Th1/Th2 polarization, activated naive and memory T cells, and T-cell clones, in which the intracellular synthesis of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) and the surface expression of CD30 and LAG-3 were also assessed. Moreover, by using immunohistochemistry the in vivo expression of CCR3, CCR5, CXCR3, and CXCR4 was examined in the gut of patients suffering from Crohn's disease, a Th1-dominated disorder, and in the skin of patients suffering from systemic sclerosis, a Th2-dominated disorder. CCR5 and LAG-3 exhibited the same pathway of Th1 association, whereas CXCR3 did not discriminate between Th1- and Th2-dominated responses. On the other hand, CCR3 was found only occasionally in a small proportion of allergen-specific memory T cells with Th2/ThO profile of cytokine production in vitro. However, it was neither seen in Th2-polarized activated naive T cells nor in established Th2 clones and could be detected in vivo only on non-T cells. Finally, whereas CXCR4 expression was not limited to Th2 cells in vivo, it was markedly up-regulated by IL-4 and down-regulated by IFN-gamma in vitro. Thus, the results of this study confirm the existence of flexible programs of chemokine receptor expression during the development of Th1 and Th2 cells. However, caution is advised in interpreting these receptors as surrogate markers of a given type of effector response.

Clone Cells↗
PubMed1999

[Contralateral transinguinal laparoscopy in unilateral inguinal hernia].

BACKGROUND: Indication for surgical exploration of the contralateral groin during unilateral herniorraphy in children is the subject of a worldwide debate. Routine exploration based on the likelihood of a patent processus vaginalis (PV) according to age, gender or side to some extent leads to unnecessary procedures, while routine abstention may leave a peritoneal sac, likely to later induce a symptomatic hernia in about 10% of cases. METHODS AND PATIENTS: One hundred and twenty-five children aged from 1 month to 15 years underwent transinguinal laparoscopic assessment of the contralateral groin, using a 3 mm trocar and a 70 degrees telescope gently introduced through the exposed PV. Surgical exploration was performed only in those patients who exhibited a patent PV, and in patients where the groin was poorly visualized due to technical problems. RESULTS: Regardless of age, contralateral surgery was not considered in 88 (70%) of the 125 children. Among the 37 patients that were operated upon, eight had a negative exploration due to an erroneous endoscopic evaluation. Surgery was avoided in 35 (56%) of the 62 infants aged less than 2 years, including nine of the 13 prematures who were previously routinely operated upon. Conversely, in the 63 older patients who were readily spared from surgical exploration, the videoscopic evaluation allowed appropriate selection for contralateral surgery in six. CONCLUSION: A routine policy, either of surgery or observation, is no longer indicated as a quick, safe and cost-effective method is available to detect a patent PV. The transinguinal laparoscopy is safe and could be easily performed by surgeons already skilled in pediatric herniorraphy. Therefore, the videoscopic transinguinal contralateral evaluation is worth being promoted to ensure an appropriate surgery tailored to the anatomical features.

Adolescent↗
PubMed1999

Role for interactions between IP-10/Mig and CXCR3 in proliferative glomerulonephritis.

The mechanisms responsible for mesangial cell proliferation in proliferative glomerulonephritis are only partially understood. This article reports the results of an immunohistochemical study showing high expression of the chemokine receptor CXCR3 by mesangial cells of patients with IgA nephropathy, membranoproliferative glomerulonephritis, or rapidly progressive glomerulonephritis. CXCR3 was also detectable by flow cytometry in cultured human mesangial cells, in which it appeared to be functionally active, as determined by the ability of its ligand, the (interferon-gamma)-inducible protein of 10 kD (IP-10) to induce intracellular Ca2+ influx. Both IP-10 and the monokine induced by interferon-gamma (Mig) were also effective in inducing proliferation of human mesangial cells. These data suggest that in patients with proliferative glomerulonephritis, the chemokines IP-10 and/or Mig not only may act as chemoattractants for infiltrating mononuclear cells in the inflamed tissue, but also may directly induce the proliferation of mesangial cells.

Adult↗