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Biomedical subjects

F Bortolotti

Publications and source records attributed to F Bortolotti.

At least 127 records · Page 7Linked to original sources
PubMed1986

Natural killer activity in patients with acute viral hepatitis.

Using the natural killer (NK) sensitive K562 cell line, enhanced NK cell cytotoxicity was demonstrable early in the course of acute hepatitis B while normal values were obtained in patients studied during convalescence. No evidence of enhanced NK activity was instead obtained in the course of acute non-A, non-B hepatitis. Serum levels of alpha-interferon, as determined by radioimmunoassay (RIA), were significantly increased in patients with acute hepatitis B showing enhanced NK cell activity but not in those with acute non-A, non-B hepatitis and normal NK cell activity. These results suggest that natural cytotoxicity may play a role early in the course of acute hepatitis type B, before antigen-specific T lymphocytes become fully operative.

Acute Disease↗
PubMed1985

Different mechanisms responsible for in vitro cell-mediated cytotoxicity to autologous hepatocytes in children with autoimmune and HBsAg-positive chronic liver disease.

To investigate mechanisms of hepatocyte injury, lymphocytes from 41 children with chronic liver disease were incubated with autologous liver cells in a microcytotoxicity assay. Cytotoxicity was significantly increased in 18 of 25 patients with chronic hepatitis B virus (HBV) infection, in five of nine with "autoimmune" chronic active hepatitis (CAH), and in only one of seven with histologically inactive liver disorders. There was a good correlation between cytotoxicity and biochemical and histologic markers of disease activity in children with autoimmune CAH, whereas in HBsAg-positive disease a positive correlation was found only with serum alanine aminotransferase (SGPT). Children with autoimmune CAH receiving steroid treatment had normal cytotoxicity, whereas increased values were found in two of three HBsAg-positive patients receiving prednisolone. Fractionation studies revealed that non-T cells were cytotoxic in both autoimmune and HBcAg-positive chronic liver disease. T cell cytotoxicity was exclusively found in children with chronic HBV infection, particularly with HBc antigenemia. Blocking experiments showed that T-lymphocytes from HBsAg-positive children reacted with HBV core antigen on the hepatocyte surface. Non-T cells were directed against hepatocyte membrane antigens in both HBsAg-positive and HbsAg-negative children. These results suggest that different immune mechanisms of liver damage are involved in autoimmune and HBsAg-positive chronic liver disease.

Adolescent↗
PubMed1985

Prognostic value of hepatitis B core antigen (HBcAg) expression in the liver of children with chronic hepatitis type B.

During a prospective follow-up study of 65 children with chronic hepatitis B, the HBcAg expression pattern in the liver was investigated, by immunofluorescence, in relation to biochemical and histological features and to the evolution of the disease. HBcAg was detected in 50 (77%) cases, with a diffuse pattern of distribution (more than 60% positive nuclei) in 20 cases, and with a focal pattern (less than 40% positive nuclei) in 30 cases. The diffuse pattern significantly prevailed in younger children, while the focal pattern was more frequent in children beyond 10 years of age. Transaminase levels were higher and histological features of activity were more frequent in patients with the focal pattern than in those with a diffuse pattern. Twenty-five hepatitis B e antigen (HBeAg) positive children, all initially HBcAg positive, were followed prospectively for 24 months. Seroconversion to anti-HBe, with subsequent normalization of transaminases, occurred in 72% of cases with a focal pattern, but only in 21% of those with a diffuse HBcAg pattern. In four patients transition from the diffuse to the focal pattern was observed during follow-up. These results suggest that, in children with chronic hepatitis B, the diffuse HBcAg pattern in the liver might reflect an earlier phase of infection. In HBeAg positive cases the focal HBcAg pattern may represent a prognostic marker of short-term favourable evolution of the disease.

Child↗
PubMed1985

Hepatitis B virus replication in acute glomerulonephritis with chronic active hepatitis.

A 3 year old boy who had chronic active hepatitis type B with features of ongoing liver damage and active virus replication, developed acute membranous glomerulonephritis two years after the clinical onset of liver disease, when both hepatitis B e antigen and antibody were detectable in serum. After withdrawal of short term steroid treatment and resolution of hepatitis B virus replication, both glomerulonephritis and chronic hepatitis went into remission. Some months later hepatitis B surface antigen was no longer found in serum.

Acute Disease↗
PubMed1985

Infection with the delta agent in children.

Serological evidence of infection with the hepatitis B virus associated delta agent (delta) was found in 34 of 270 Italian children with HBsAg-positive liver disease. In different histological forms of chronic HBsAg hepatitis the prevalence of delta infection increased in parallel with the activity of the disease and was maximal in children with cirrhosis. During two to seven years of follow up the hepatitis deteriorated in 38% of the 34 patients with delta infection and ameliorated only in 9%. By contrast the disease usually ran a mild course in the 236 delta-negative carriers of HBsAg, with remission in 55% of these children and deterioration in only 7%. The outcome of chronic hepatitis associated with delta infection was not influenced by treatment with steroids and azathioprine. Chronic delta infection in children is usually accompanied by serious liver disease, that has a tendency to progress and is unresponsive to conventional immunosuppressive treatment.

Adolescent↗
PubMed1984

Circulating hepatocyte membrane-specific autoantibodies in chronic active hepatitis type B. Relation to virus replication activity and liver cell necrosis.

Sera from two groups of untreated HBsAG-positive patients with chronic active hepatitis on liver biopsy were tested for antibodies to liver cell membrane antigens (liver-specific protein, LSP; and liver membrane antigen, LM-Ag). Among the 14 HBeAg-positive cases, seven (50%) were positive for anti-LSP, whereas only two (13%) of 15 anti-HBe-positive cases circulated this antibody. Liver membrane autoantibody (LMA) was detected only in two sera from delta-positive patients (1 HBeAg positive and 1 anti-HBe positive). Anti-LSP-positive patients presented transaminase values significantly higher than those of the negative cases. Our data do not support the hypothesis that a liver-specific autoimmune mechanism plays a significant role in the immunopathogenesis of liver cell necrosis in anti-HBe-positive chronic active hepatitis type B. The relationship between hepatocyte necrosis and anti-LSP antibody response is confirmed.

Adult↗
PubMed1983

Virus replication and liver disease in chronic hepatitis B virus infection.

Recent studies on the natural history of chronic hepatitis B virus infection have provided evidence for a close temporal relationship between the phase of active virus replication and development of liver lesions. To assess the role that virus replication plays in this phase in determining the severity of the liver disease, we studied serum levels of virus-specific DNA-polymerase activity and hepatitis Be antigen/antibody status in 48 chronic carriers of the hepatitis B surface antigen found positive for the hepatitis B core antigen in the liver. There was a remarkably evident inverse correlation between virus replication activity and liver disease activity, patients with minimal histological changes having the highest DNA-polymerase levels (mean +/- SD: 3879 +/- 2557 cpm) and those with severe chronic active hepatitis the lowest enzyme levels (419 +/- 246 cpm), while cases of chronic persistent hepatitis and of mild chronic active hepatitis had intermediate levels. Serum hepatitis Be antigen was detected in 31/32 patients with milder liver lesions and in 11/16 with severe liver lesions; the remaining five cases were anti-HBe-positive despite the presence of the core antigen in the liver. Serum levels of virus replication markers closely correlated with the distribution pattern of the core antigen in the liver. These findings indicate that in chronic hepatitis B the severity of liver disease is not directly related to levels of virus replication, thus suggesting a predominant role of host immune mechanisms.

Carrier State↗
PubMed1983

Changes in hepatitis Be antigen/antibody system in children with chronic hepatitis B virus infection.

The long-term changes in the HBeAg/anti-HBe system were examined in 55 children with chronic type B hepatitis (52 patients) or cirrhosis (three patients) during a follow-up period of two to 10 years. At the time of presentation, positive reactions to HBeAg were seen in 46 children, and to anti-HBe in nine. Spontaneous seroconversion from HBeAg to anti-HBe occurred in 13 of 38 patients (average annual rate 16%), mainly those with acute onset of hepatitis B or with features of active liver disease at presentation and with a focal distribution pattern of hepatitis B core antigen in the liver. Normalization of transaminase activity and disappearance of histologic features of activity were the rule in patients in whom seroconversion occurred, but the exception in those who maintained persistently HBeAg-positivity. In contrast to the favorable evolution of illness observed in children showing anti-HBe seroconversion, three of nine patients who had anti-HBe-positive reactions at presentation were found to have liver cirrhosis, and a fourth patient had features of active hepatitis throughout the observation period. Because delta antigen was detected in the liver in two of these patients, it is conceivable that etiologic cofactors could have influenced their course of chronic hepatitis.

Adolescent↗
PubMed1983

A 7 year survey of acute hepatitis type B.

Epidemiological and clinical features of acute symptomatic hepatitis type B were evaluated in 51 otherwise healthy children and in 13 children receiving immunosuppressive treatment for leukaemia and malignancy, who were admitted to hospital with acute hepatitis B surface antigen (HBsAg) positive hepatitis during a period of 7 years. Blood transfusions, or intimate contacts with asymptomatic HBsAg carriers or with contaminated material during repeated admission to hospital were the possible sources of infection in the immunosuppressed patients, whereas percutaneous exposure was identified as the source in a minority of non-immunosuppressed patients. Features of the acute phase of the illness differed little between the two groups of patients (acute liver failure developed in one patient with leukaemia and in two untreated children). Conversely, chronic evolution was observed in 69% of immunosuppressed patients but in only 9% of untreated children and affected only patients born to HBsAg positive mothers (two of four patients) or patients presenting with papular acrodermatitis (both patients).

Age Factors↗
PubMed1983

Virus-associated receptors for polymerized human serum albumin in acute and in chronic hepatitis B virus infection.

The receptor for polymerized human albumin, recently identified on the hepatitis B virus, was studied by hemagglutination in 89 patients with acute and chronic hepatitis B virus infection. The receptor, which was differentiated from antialbumin antibodies by immunofluorescence and hemagglutination inhibition, was detected mainly in patients with active virus replication, independently of hepatitis B surface antigen titer. Thirteen of 20 uncomplicated acute hepatitis B cases were positive at clinical onset (mean log2 titer +/- SD: 4.20 +/- 2.46) but became negative during the acute phase, while 5 patients who progressed to chronic hepatitis had significantly higher receptor titers at onset (7.0 +/- 0.0, p less than 0.01) and remained positive afterwards. In chronic hepatitis B virus infection, the receptor was detected in 17 of 30 patients with chronic active hepatitis, in 5 of 12 with chronic persistent hepatitis, and in 2 of 16 healthy carriers. Among hepatitis B e antigen positive cases a wide range in receptor levels was observed, and in longitudinal studies most patients with low initial titers seroconverted to hepatitis B e antibody while patients with higher titers remained persistently hepatitis B e antigen positive. These results indicate that the virus receptor for polyalbumin may represent a useful marker in hepatitis B e antigen positive acute and chronic hepatitis B.

Antibody Formation↗
PubMed1983

Structural investigations on pharmaceutical enzymes. Ornithine transcarbamylase (OCT) from bovine liver.

Ornithine transcarbamylase (OCT) is one of the urea-cycle enzymes in mitochondria which is involved in metabolic disorders in man. Reye's syndrome, characterized by encephalopathy and fatty infiltration of the liver, is one of such diseases. During this syndrome a reduction of OCT specific activity was observed, probably due to increased proteolytic degradation or to alteration in the enzyme conformation. It has recently been found that OCT administration to patients with liver disorders, contributes to illness resolution. Since the therapeutic properties of the enzymes are usually related to their structure, this paper reports some findings obtained by spectroscopic measurements on OCT structure and conformation stability in solution.

Animals↗
PubMed1982

Isolation and characterization of a new form of the porcine pancreatic secretory trypsin inhibitor. Biochemical studies and high-resolution 1H-NMR.

A new active form of porcine PSTI (pancreatic secretory trypsin inhibitor) was isolated during the fractionation by ion-exchange chromatography of the already known forms PSTI I and II. Biochemical and 1H-NMR techniques were used to characterize the new inhibitor, which is referred to as PSTI III. The amino acid composition, the nature of the N-terminal residue and data obtained from the tryptic peptides and indicate that PSTI III lacks the N-terminal octapeptide of PSTI I; hence, it starts and ends with disulfide bridges. The conclusion is supported by the 1H-NMR spectrum of the protein at 270 MHz. The biological activity and the most prominent conformational and dynamic features of forms I and II are retained in inhibitor III. However, PSTI III appears to be less compact than its parent forms I and II, suggesting that in the latter inhibitors an interaction between the N-terminal tail and the bulk of the protein may contribute to the overall stability. The genetic origin of PSTI III is discussed.

Amino Acid Sequence↗
PubMed1982

Catalytic properties of human urinary kallikrein.

Kinetic studies have been carried out with a well-characterized preparation of human urinary (h.u.) kallikrein using chromogenic substrates. Steady-state and pre-steady-state data for h.u. kallikrein catalyzed hydrolysis of N alpha-carbobenzoxy-L-lysine p-nitrophenyl ester (ZLysONp) and of N alpha-carbobenzoxy-L-alanine p-nitrophenyl ester (ZAlaONp) in the presence and absence of ethylamine and acetamidine have been obtained under various conditions and have been analyzed in the framework of the minimum three-step mechanism: (formula see text) The pH dependencies of the kinetic parameters for the hydrolysis of ZLysONp and ZAlaONp in the presence of saturating levels of ethylamine and acetamidine show that at acid pH values (less than or equal to 4) the k3 step (deacylation) is rate limiting in catalysis, whereas for pH values greater than or equal to 6, k2 (acylation) becomes rate limiting. On the other hand, the acylation step is rate limiting in the enzymatic hydrolysis of ZAlaONp over the whole pH range explored. Saturating concentrations of acetamidine increase, more than those of ethylamine, kcat for the hydrolysis of ZAlaONp. The affinity of h.u. kallikrein for acetamidine and ethylamine changes about 5-fold with pH between pH 5 and 3. The pH dependence of the spectral properties of free hu. kallikrein reflects the ionization of a group with a pKa value of 4.45 +/- 0.1. The results point out that, similarly to bovine beta-trypsin, h.u. kallikrein catalysis involves an ionizable group which has a pKa of about 4.5 in the free enzyme and a pKa of about 3.7 in the enzyme bound to cationic substrates or ligands.

Amidines↗