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Biomedical subjects

G Visentin

Publications and source records attributed to G Visentin.

12 recordsLinked to original sources
PubMed2006

Cytolytic function and survival of natural killer cells are severely altered in myelodysplastic syndromes.

Natural Killer (NK) cells are critical in host defense against malignant transformation and are potent antileukemic cytotoxic effectors. In the present study, we investigated the peripheral NK function in patients with myelodysplastic syndromes (MDS). We demonstrated that the peripheral NK cell population was quantitatively normal in MDS patients. Furthermore, NK cells displayed an expression of the activating natural cytotoxicity receptors (NCR) NKp46 and NKp30 as well as NKG2D similar to that observed in donors, but exert a highly decreased constitutive cytolytic activity compared to resting normal NK cells. Although activation with IL-2 resulted in the upregulation of NKp46 expression by MDS-NK cells, their cytolytic function remained deeply altered as compared to activated donor NK cells. In addition, MDS NK cells did not proliferate in vitro, and displayed an increased rate of apoptosis in response to IL-2 stimulation although the spontaneous apoptosis was not significantly increased. Interestingly, a proportion of peripheral MDS-NK cells were derived from the MDS clone as the cytogenetic anomaly found in bone marrow karyotype was also detected in 20-50% of circulating NK cells. In conclusion, NK cells' cytolytic function and proliferative capacities in response to activation by cytokines are profoundly altered in MDS.

Apoptosis↗
PubMed2001

Identification of T cells responding to a self-protein modified by an external agent.

An interesting class of immune responses is that in which an environmental agent modifies a self-protein. Heparin induced thrombocytopenia (HIT) is associated with an antibody response in which the immunogen is a self-protein, platelet factor 4 (PF4), modified by an external agent, heparin. We tested the hypothesis that a T cell component exists in HIT, which like the humoral response, also requires the combination of heparin and PF4 to be activated. We identify here, a subset of T cells derived from a subject with severe HIT, which were expanded preferentially in 14-day in vitro cultures specifically in the presence of PF4:heparin complexes. A combination of T cell receptor spectratyping, CDR3 sequencing, and clonotype-specific probe hybridization were used to identify the responding T cells. The three BV17 T cell "clonotypes" thus identified had a CDR3 length of 10 amino acids, used BJ1.2, and displayed a conserved CDR3 sequence motif. These T cells are an example of a cellular response to environmentally altered self and are likely to be directly involved in HIT by functioning as T helper cells. The results are discussed in terms of the possible role of modification of antigen presentation by the external agent in this response.

Aged↗
PubMed1990

Effects of chronic ethanol treatment on alpha-MSH concentrations in rat brain and pituitary.

Male Sprague-Dawley rats were chronically treated with a liquid diet containing 6.5% (v/v) ethanol or equicaloric sucrose. Rats were killed after 21 days of treatment. alpha-MSH-like immunoreactivity was measured in the intermediate lobe of the pituitary gland and in several brain regions. Chronic ethanol treatment significantly reduced alpha-MSH-like immunoreactivity in the pituitary gland; in the arcuate nucleus of the hypothalamus and in the substantia nigra. The results of this study confirm the earlier findings that chronic ethanol treatment reduces POMC biosynthesis in the pituitary gland and in the central nervous system.

Alcoholism↗
PubMed1990

Synthesis and structure-activity relations in the class of 2-(pyridyl)penems.

The isosteric CH----N substitution in the class of 2-arylpenems results in improved antibacterial activity, with retention of the favorable characteristic of stability towards renal dehydropeptidase. High therapeutic efficacy was demonstrated in experimental mice septicemias with the 2-(3-pyridyl) derivative 2b and its orally absorbed acetoxymethyl ester prodrug 4n.

Animals↗
PubMed1983

[Anti-tissue autoantibodies in malignant pulmonary neoplasms].

Tissue antibodies (Ab) were investigated in 85 patients affected with pulmonary malignancy of different histologic type and, as control, in 40 non-smoker healthy subjects and in 40 smoker subjects with chronic bronchitis. A significantly higher number of patients (64, 7%) had tissue Ab in comparison with both control groups (17% in non smoker group and 25% in smoker and chronic bronchitis group, respectively). Antinuclear antibodies were found in 29.4% of patients, antismooth muscle in 31.7%, anti-mitochondrial Ab in 4.7%, antityroid microsomes Ab in 4.7%, anti-gastric parietal cells Ab in 4.7%, anti-reticulin Ab in 11.7%. The patients at third stage of disease showed all antibodies as well as anti-nuclear more frequently that patients at first and second stage. Antibodies to cytoplasmic antigens were found in patients with anaplastic and squamous cancer, but not in patients with adenocarcinoma. Our observations suggest that immunologic abnormalities similar to those present in autoimmune disease, may be associated to pulmonary malignancy.

Adenocarcinoma↗