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Biomedical subjects

M Baraldini

Publications and source records attributed to M Baraldini.

64 records · Page 4Linked to original sources
PubMedDate not supplied

Antioxidant properties of bile salt micelles evaluated with different chemiluminescent assays: a possible physiological role.

The antioxidant activity of a representative series of free, glycine- and taurine-conjugated bile acids was evaluated by two different chemiluminescent assays: (a) the enhanced chemiluminescence system based on horseradish peroxidase and luminol/oxidant/enhancer reagent, and (b) the hypoxanthine/xanthine oxidase/Fe(2+)-EDTA/luminol system. Bile acids were studied at final concentrations ranging from 1 to 28 mmol/L. All of the bile acids studied inhibited the steady-state chemiluminescent reaction and the extent of inhibition depended upon the structure of the bile acids, whereas the duration was related to bile acid concentration. The mechanism of the light inhibition is probably due to trapping of oxygen free radicals generated in the chemiluminescent reactions, within bile acid micelles. The free radicals trapped into micelles reduced the formation of luminol radicals and consequently the light output; when the micelles were saturated, the oxygen free radicals in solution again produced luminol radicals. The micelle interaction with reactive oxygen species could be a physiological mechanism of defence against the toxicity of those species in the intestinal content. On the other hand, alterations in bile acid organ distribution, concentration and composition leads to a membrane damage caused by their detergent-like properties, which could be associated to oxygen free radical production.

Antioxidants↗
PubMedDate not supplied

Hepatocyte membrane-bound IgG and circulating liver-specific autoantibodies in chronic liver disease: relation to hepatitis B virus serum markers and liver histology.

Hepatocytes isolated from 101 biopsies were examined for membrane-bound IgG. The sera of the patients were tested for anti-liver-specific lipoprotein by radioimmunoassay and for liver membrane autoantibody (by indirect immunofluorescence on isolated rabbit hepatocytes. The seven patients with normal liver or minor nonspecific alterations were negative for membrane IgG and serum antibodies. Membrane IgG with granular distribution was found in 41 patients [21 hepatitis B virus-related chronic active hepatitis (CAH), 3 cryptogenic CAH, 3 chronic persistent hepatitis, 6 prolonged viral hepatitis, 1 alcoholic cirrhosis, and 6 primary biliary cirrhosis]. Membrane IgG with linear fluorescence pattern was detected in 12 cases (4 autoimmune CAH, 3 HBsAg-positive CAH, 2 alcoholic cirrhosis, 1 anti-HBc positive CAH, 1 cryptogenic CAH, and 1 prolonged viral hepatitis). A strong association between granular IgG and serum HBsAg was found. Nuclear localization of IgG was found in 34 patients and correlated with the positivity of granular membrane IgG. The highest prevalence of anti-liver-specific lipoprotein was found in primary biliary cirrhosis and autoimmune CAH cases which were also positive for liver membrane autoantibody. No relationship was found between the presence of membrane IgG and circulating liver-specific autoantibodies. Membrane IgG and anti-liver-specific lipoprotein correlated with the presence of moderate and severe portal inflammatory infiltration but not with piecemeal necrosis or transaminase levels. Eleven of the twelve patients with linear membrane IgG presented chronic active liver disease with moderate to severe signs of liver damage. Therefore, it is suggested that, while granular membrane IgGs are related to hepatitis B virus, antigenic expression on the hepatocyte surface and/or the presence of immune complexes, linear membrane IgG could play a role in the immunopathogenesis of liver cell damage particularly in "autoimmune" cases which present high percentages of positive cells liver-specific autoantibodies.

Adult↗
PubMedDate not supplied

Serum binding activity for polymerized human albumin due to antibodies detected by enzyme-linked immunosorbent assay in acute and chronic type B, A and NANB viral hepatitis.

Polymerized human serum albumin (pHSA) binding activity due to antibodies was evaluated by a sensitive and specific enzyme-linked immunosorbent assay (ELISA) in well characterized cases of acute (AVH) and chronic active (CAH) viral hepatitis. Moreover, hepatitis B virus (HBV) infection serum samples were tested for the presence of HBsAg-associated pHSA receptors detected by radioimmunoassay. Specificity of ELISA in detecting pHSA binding activity due to antibodies was assayed by testing IgG fractions from positive serum samples and purified HBsAg particles. A very high prevalence (mean = 87%) of antibody response to pHSA was detected in serum samples of patients with type B, A and post-transfusion non-A, non-B (NANB) AVH and CAH. IgM antibodies were found in 75% of type B AVH, in 77% of type A AVH and in none of the NANB cases at the onset of illness. In CAH, IgM antibodies were found in 37.5% of HBsAg-positive cases and in 44% of NANB cases. In HBV-related AVH and CAH no correlation was found between anti-pHSA antibodies and HBsAg-associated pHSA receptors or the HBeAg/anti-HBe status. The antibody response detected by ELISA showed a cross-reactivity with monomeric human albumin and heterologous polymeric and monomeric albumins. However, in HBV infection the antibody binding was significantly higher for pHSA than for monomeric human albumin or albumins from other species, thus suggesting that the antigenic sites of pHSA evoking the antibody response may differ in relation to the etiology of viral hepatitis.

Autoantibodies↗
PubMedDate not supplied

Clinical significance of antibodies to polymerized human albumin detected by enzyme-linked immunosorbent assay.

Antibodies directed against glutaraldehyde-polymerized human serum albumin (pHSA) were tested by a sensitive and specific enzyme-linked immunosorbent assay (ELISA) in serum samples from 196 patients with various hepatic and non-hepatic diseases and in 38 healthy control subjects. A very high prevalence (80.1%) of antibody response was found in the patient group, ranging from 60% in type non-A, non-B (NANB) chronic active hepatitis (CAH) and lymphomas to 95.5% in hemodialysis patients. A higher prevalence of anti-pHSA antibodies was found in hepatitis B virus (HBV)-related CAH and hemodialysis patients compared with NANB-related CAH, collagen diseases and lymphomas. Anti-pHSA antibodies were most frequent in HBsAg-positive cases, but no correlation between antibody response and the HBeAg/anti-HBe status was found among these patients. Anti-pHSA antibodies did not correlate with HBsAg-associated pHSA receptors determined by radioimmunoassay (RIA). Moreover, a significantly higher pHSA receptor expression was found in HBV-related CAH and hemodialysis patients compared with chronic HBsAg carriers and in HBeAg-positive patients compared with HBeAg-negative cases. The anti-pHSA response seems to be related to the presence of immunoregulation disorders which may be induced by several causes, such as autoimmunity and viral infections. In particular, as far as the HBV infection is concerned, there is no evidence that circulating anti-pHSA antibodies interfere with the natural course of the disease.

Autoantibodies↗
PubMedDate not supplied

Role of prostaglandin E2 on defective interferon-gamma production during type B acute viral hepatitis.

Interferon-gamma (IFN-gamma) and prostaglandin E2 (PGE2) production was evaluated in cultured peripheral blood mononuclear cells taken from patients with type B acute viral hepatitis at the onset of symptoms, at 1st and 2nd week of disease, and from healthy controls. Concanavalin A-stimulated cells cultured for 24, 48 and 72h showed significantly higher IFN-gamma levels compared to basal release in both groups, whereas no statistically significant differences were found in most experimental conditions as regard PGE2 synthesis. No differences were found in IFN-gamma production by comparing patients with acute viral hepatitis to the control group, whereas PGE2 was significantly increased during the disease. IFN-gamma and PGE2 levels did not show any significant change in acute viral hepatitis during the follow-up. A statistically significant correlation was found only in control group between IFN-gamma and PGE2 levels in unstimulated cultures. PGE2 seems to play a central role in regulating interferon production during viral infection. This may suggest a new therapeutic approach in viral hepatitis utilizing a combination of interferon and prostanoid inhibitory substances, above all in patients who do not respond to interferon therapy alone.

Acute Disease↗
PubMedDate not supplied

Bio- and chemiluminescence in bioanalysis.

Analytical chemiluminescence and bioluminescence represent a versatile, ultrasensitive tool with a wide range of applications in diverse fields such as biotechnology, pharmacology, molecular biology, clinical and environmental chemistry. Enzyme activities and enzyme substrates and inhibitors can be efficiently determined when directly involved in luminescent reactions, and also when they take part in a reaction suitable for coupling to a final light-emitting reaction. Chemiluminescence detection has been exploited in the fields of flow-injection analysis and column-liquid chromatographic and capillary-electrophoretic separative systems, due to its high sensitivity when compared with colorimetric detection. It has widely been used as an indicator of reactive oxygen species formation in cells and whole organs, thus allowing the study of a number of pathophysiological conditions related to oxidative stress. Chemiluminescence represents a sensitive and rapid alternative to radioactivity as a detection principle in immunoassays for the determination of a wide range of molecules (hormones, food additives, environmental pollutants) and in filter membrane biospecific reactions (Southern, Northern, Western, dot blot) for the determination of nucleic acids and proteins. Chemiluminescence has also been used for the sensitive and specific localization and quantitation of target analytes in tissue sections and single cells by immunohistochemistry and in situ hybridization techniques. A relatively recent application regards the use of luminescent reporter genes for the development of bioassays based on genetically engineered microorganisms or mammalian cells able to emit visible light in response to specific inorganic and organic compounds. Finally, the high detectability and rapidity of bio- and chemiluminescent detection make it suitable for the development of microarray-based high throughput screening assays, in which simultaneous, multianalyte detection is performed on multiple samples.

Animals↗
PubMedDate not supplied

Assessment of portal hypertension by endoscopic ultrasonography.

Endoscopic ultrasonography (EUS) was performed in 40 patients with portal hypertension (PH) and in 48 control subjects. The azygous, splenic, mesenteric, and portal veins were displayed in both groups. However, esophageal and gastric varices, periesophageal and perigastric collateral veins, and submucosal gastric venules were displayed only in patients with portal hypertension. EUS was inferior to endoscopy in detecting and grading esophageal varices (p less than 0.0005), but EUS was superior in the detection of varices in the fundus of the stomach (p less than 0.0005). Detection of periesophageal veins by EUS increased with increasing diameter of esophageal varices at endoscopy (57% in grade 1, 89% in grade 2, and 100% in grade 3), and there was a direct correlation between endoscopic grade and the diameter of the periesophageal collateral veins at EUS. The diameter of the azygous vein by EUS at its distal and proximal margins was significantly greater in patients with PH (p less than 0.001); the EUS diameter of the azygous vein was significantly larger with variceal grade 2 compared with grade 1 (p less than 0.02 and p less than 0.01, respectively). In portal hypertensive gastropathy, endoscopic and EUS detection were coincident. No correlation was found between the presence of portal hypertensive gastropathy, endoscopic grade of esophageal varices, and detection of gastric varices at EUS.

Adult↗
PubMedDate not supplied

Prostanoids in peritoneal fluid of infertile women with pelvic endometriosis and PID.

Peritoneal fluid collected at celioscopy in infertile subjects was assayed for steroids and several prostanoids (PGE2, PGF2, TXB2, LTB4) as part of a study into pathophysiology of the female reproductive tract. Prostaglandins, produced massively in the pelvis, might interfere with fertility through various mechanisms (alterations in the egg implantation, follicle genesis, luteinization as well as tubal disorders). Our study of 54 patients showed a marked increase only of TXB2 out of the prostanoids assayed in overall endometriosis. In pelvic flogosis peritoneal LTB4 (and TXB2) were considerably increased if related to controls. This would suggest their role in the ethiopathogenesis of unexplained infertility (in relation to these pathologic patterns).

Ascitic Fluid↗