PubMed Health⌕ Search

Biomedical subjects

M Mazzetti

Publications and source records attributed to M Mazzetti.

At least 55 records · Page 3Linked to original sources
PubMed1984

Analysis with OKT monoclonal antibodies of T-lymphocyte subsets present in blood and liver of patients with chronic active hepatitis.

The relative distribution of T lymphocyte subsets, as defined by the monoclonal antibodies OKT, was determined by cytofluorimetric analysis in peripheral blood and in cells isolated from liver biopsies of 31 patients with chronic active hepatitis (CAH). The percentage of peripheral blood lymphocytes binding OKT8 (directed against cytotoxic/suppressor T cells) was found to be elevated in patients with HBsAg and HBeAg positive chronic active hepatitis. Patients with CAH who had seroconverted to anti-HBe, had an increased number of OKT3-positive cells in their blood, which was directed against a common T cell surface antigen, associated with a decreased number of OKT8 positive cells. Lymphocytes isolated from liver biopsies of patients with CAH presented a general increase of OKT8-positive cells associated with a decreased number of OKT4-positive (helper/inducer) T cells. It is likely that OKT8-positive cells found in liver biopsies represent cytotoxic T cells directed against either viral or liver cell determinants.

Adult↗
PubMed1983

Lymphocytotoxicity against autologous hepatocytes and membrane-bound IgG in viral and autoimmune chronic active hepatitis.

Membrane-bound IgG and lymphocytotoxic activity of total, T-enriched and T-depleted lymphocytes, using autologous hepatocytes have been evaluated in: (a) 31 patients with chronic active hepatitis (CAH) (six autoimmune and 25 hepatitis B virus - HBV-related); (b) five patients with inactive alcoholic cirrhosis; and (c) nine subjects with normal hepatic histology. Lymphocytotoxicity was positive in 83% of autoimmune CAH and 68% of HBV-related cases; it was confined to the T-depleted subpopulation in the first group, while it was present in both the T-enriched and T-depleted subpopulations in 81% of HBV-related cases. Membrane-bound IgG was present in 58% of group (a) and in none of the other groups. A linear pattern was found in four out of five autoimmune CAH patients with positive lymphocytotoxic activity. The autoimmune patient with lymphocytotoxic activity within the normal range did not show any membrane fluorescence. Among HBV-related CAH patients, 13 presented a granular pattern, two an associated granular and linear pattern and ten were negative. These data suggest that different lymphocytotoxic mechanisms are involved in the two forms of CAH studied.

Autoantibodies↗
PubMed1981

[Effect of 2 mercaptopropionylglycine on the cytotoxic activity of lymphocytes from patients with chronic active hepatitis against rabbit hepatocytes isolated and cultured in vitro].

"In vivo" and "in vitro" action of 2 MPG on lymphocytotoxic activity was evaluated in 22 patients with CAH, 14 were HBsAg positive and 8 were negative. The test was performed with and without 2 MPG in the colture medium, and before and after treatment. HBsAg+ patients received 2 MPG treatment, while HBsAg- ones received immunosoppressive therapy and 4 of these were on 2 MPG treatment as well. Cytotoxic Index was reduced non-significantly by addition of 2 MPG in colture medium in both groups. 2 MPG treatment does not modify cytotoxic activity which is reduced by immunosoppressive therapy. These findings suggest a positive effect of 2 MPG on liver-cell metabolism with an increased resistence of the epatocyte to the "in vitro" lymphocytes aggression. Hence it may be suggested an association treatment with immunosoppressive agents and 2 MPG.

Amino Acids, Sulfur↗
PubMed1980

[Separation and characterization of human T G and T M lymphocyte populations].

During the last few years a number of experimental evidences have shown the presence of Fc receptors for IgG or IgM on the membrane of human T cells. These two different receptors are detectable and mutually exclusive on distinct cell populations named respectively TG, TM and T "null" (which lack detectable receptors). Studies on the functional activities of these cells have shown that TM and TG lymphocytes play an antitetical role in regulating B cell response, TM exerting an "helper" activity on the differentiation of B lymphocytes while TG having a "suppressor" one. The aim of this study has been to determine the values of these two subpopulations in a group of twenty control subjects. Our results have shown that TG constitute 10%, whereas TM represent 40% of the total T cells. After EA-G rosetting, the purification of this subpopulation on a density gradient has shown an enrichment of more than 90% in TG cells, while TM contaminate this fraction for less than 4%. The purity of the fraction containing TM has been evaluated using the localization of alpha-naphthyl acetate esterase activity, which has shown that more than 88% of the cells in this fraction are positive for this enzyme.

Adult↗
PubMedDate not supplied

Increased production of IgE protein and IgE antibodies specific for fungal antigens in patients with the acquired immunodeficiency syndrome.

Levels of IgE protein and IgE antibodies specific for 8 different allergenic extracts were measured in the serum of a large series of patients infected by the human immunodeficiency virus (HIV) and in HIV-seronegative subjects belonging to the same risk groups (intravenous drug-users, homosexual men and hemophiliacs). The proportion of subjects showing elevated IgE levels was higher among HIV-infected patients with group IV disease than among HIV-infected patients with group II-III diseases or seronegative individuals. In addition, many HIV-infected patients with elevated IgE levels showed the presence in their serum of IgE antibodies specific for fungal antigens.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Screening and confirmatory tests for antibody to HTLV-III/LAV retrovirus in individuals at risk for AIDS.

The prevalence of specific antibodies to HTLV-III/LAV retrovirus was investigated during 1985 in a large group of subjects at risk for AIDS living in the Florence area. Two hundred and thirty-two of 774 (29.9%) intravenous drug users (IDU), 40 of 164 homosexuals (24.3%), 43 of 147 hemophiliacs (29.2%), 7 of 10 children born from IDU mothers and 4 of 88 heterosexual partners of IDU were found to be seropositive using different ELISA kits. The positivity in all serum samples showing low antibody titres and/or discordant results with different sandwich ELISA kits was confirmed by a competition ELISA assay and the Western blot technique. Serum samples from 4 of 210 hemodialyzed and from one of 17 polytransfused patients also showed positive reactions in the assays based on the sandwich principle, but gave negative results in both the competition ELISA assay and the Western blot technique. In addition, all these sera showed positive reactions using immunofluorescence and ELISA procedures that control for reactivity with H9 human cell line material used for culturing the HTLV-III/LAV retrovirus. These data demonstrate that exposure to HTLV-III/LAV retrovirus is widespread in groups of subjects at risk for AIDS living in the Florence area. Furthermore, the results of the present study suggest that, in addition to the Western blot technique, the competition ELISA assay as well as assays that control reactivity with H9 human cell line material may be of value for detecting false positive reactions due to antibody cross-reactive with human cellular components.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

In vitro infection with HIV of antigen-specific T cell clones derived from HIV-seronegative individuals. Effects on cytokine production and helper function.

Three human T cell clones (TCC) specific for purified protein derivative of Mycobacterium tuberculosis were incubated in the presence of polybrene and phytohemagglutinin with irradiated mononuclear cells from one individual exhibiting seropositivity for human immunodeficiency virus (HIV) and high levels of circulating p24 antigen. After three weeks, TCC showed HIV integration in their DNA, as shown by polymerase chain reaction analysis and Southern blot technique. All the three HIV-infected TCC maintained their ability to recognize the specific antigen, even if their proliferative ability was reduced. The ability of the HIV-infected TCC to produce IL-2, IL-4 and IFN-gamma in response to phorbol myristate acetate plus anti-CD3 monoclonal antibody was decreased, whereas their ability to produce TNF-alpha was unaffected or even enhanced. Two out of the three HIV-infected TCC showed the ability to provide helper function for polyclonal immunoglobulin production when cocultured with autologous B cells in the absence of any stimulant. These data suggest that in vitro infection of normal human TCC may provide a useful model for the study of immunological alterations induced by HIV.

Clone Cells↗
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

Influence of chronic ethanol consumption on the inositol phospholipid fatty acid composition of human peripheral blood lymphocytes.

The breakdown of inositol phospholipids is an important event after the binding of antigens to the T-cell antigen receptor. In alcoholics, changes either in early or in late steps of lymphocyte activation have been documented, however no study on the role of phosphoinositide fatty acid composition in signal transduction has been reported. We have analyzed the fatty acid pattern of phosphatidylinositol, phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5-bisphosphate from peripheral blood lymphocytes of alcoholic patients and healthy controls, in order to point out the possible compositional differences which could interfere with the signal transmission responsible for the early events in lymphocyte activation. In alcoholics, the arachidonic acid relative molar content in all the inositol phospholipid (PtdIns) fractions derived from lymphocytes was lower than in controls; all PtdIns classes appeared much more saturated than the corresponding fractions from control lymphocytes. The different fatty acid pattern of PtdIns in alcoholic patients could be responsible for an altered second messenger production, above all the production of a modified diacylglycerol which, in turn, could cause a different activation pattern of protein kinase C, with a consequent alteration in cell proliferation. The decrease in arachidonic acid molar content in the phosphoinositides and particularly in the phosphatidylinositol-4,5-bisphosphate fraction of PBL of alcoholic patients could lead to a reduced synthesis of prostanoids of the (n-6) series, and, as a consequence, to an alteration in the mitogenic response of the cells.

Adult↗
PubMedDate not supplied

Clinical features, diagnostic and therapeutic approaches to haematogenous vertebral osteomyelitis.

This article review the clinical features and the diagnostic approach to haematogenous vertebral osteomyelitis in order to optimise treatment strategies and follow-up assessment. Haematogenous spread is considered to be the most important route: the lumbar spine is the most common site of involvement for pyogenic infection and the thoracic spine for tuberculosis infection. The risk factors for developing haematogenous vertebral osteomyelitis are different among old people, adults and children: the literature reports that the incidence seems to be increasing in older patients. The source of infection in the elderly has been related to the use of intravenous access devices and the asymptomatic urinary infections. In young patients the increase has been correlated with the growing number of intravenous drug abusers, with endocarditis and with immigrants from areas where tuberculosis is still endemic. The onset of symptoms is typically insidious with neck or back pain often underestimated by the patient. Fever is present in 10-45% of patients. Spinal infections may cause severe neurological compromise in few cases, but mild neurological deficit, limited to one or two nerve roots, was detected in 28-35% of patients. The diagnosis of haematogenous vertebral osteomyelitis may be very difficult, as the symptoms can be sometimes not specific, vague or almost absent. The usual delay in diagnosis has been reported to be two to four months, despite the use of imaging techniques: in the early diagnosis of vertebral ostemyelitis is important the role of bone scintigraphy. The general principles for the management of spine infections are non operative, consisting of external immobilization and intravenous antibiotics, followed by oral antibiotics. Indications for surgery should be given in case of absence of clinical improvement after 2-3 weeks of intravenous antibiotics, persistent back pain and systemic effects of chronic infection and with presence or progression of neurological deficit in elderly or in cervical infection. Chronic ostemyelitis may require surgery in case of a development of biomechanical instability and/or a vertebral collapse with progressive deformity.

Anti-Bacterial Agents↗