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Biomedical subjects

F Malavasi

Publications and source records attributed to F Malavasi.

At least 163 records · Page 9Linked to original sources
PubMed1983

The release of platelet-activating factor from human endothelial cells in culture.

The release of platelet-activating factor (PAF) from stimulated human endothelial cells (HEC) cultured from normal term, umbilical cord veins is described. HEC in primary cultures released PAF after challenge with A23187, rabbit anti-human factor VIII (RaHu/FVIII), angiotensin II, and vasopressin. HEC subcultures maintained the ability to release PAF in the presence of A23187 and RaHu/FVIII, whereas the release of PAF in response to angiotensin II and vasopressin was not constant and was reduced. Control cultured, smooth muscle cells derived from umbilical cord veins, previously depleted of endothelial cells, did not release PAF under the above-mentioned stimulation. Plastic-adherent or cultured monocytes released PAF with A23187, but not with RaHu/FVIII, angiotensin II, and vasopressin. The release of PAF from HEC in primary cultures required the presence of extracellular cations and the activation of membrane phospholipase A2. PAF release induced by A23187, RaHu/FVIII, angiotensin II, and vasopressin was unaffected by indomethacin, an inhibitor of cyclooxygenase, which, however, favored the release of PAF from HEC stimulated with thrombin, a stimulus that did not affect HEC in the absence of indomethacin. PGI2 inhibited PAF release from stimulated HEC. The relevance of an acetylation process in the biosynthesis of PAF and HEC was supported by the following evidence: 1) the increase in PAF yield in the presence of sodium acetate and, particularly, of acetyl-CoA; 2) the incorporation of [14C]acetate into PAF molecules; 3) the loss of radioactivity and of biologic activity after treatment with phospholipase A2. These results indicate that HEC in culture are able to release PAF and that metabolic pathways similar to those described for leukocytes are involved.

Angiotensin II↗
PubMed1982

Characterization by monoclonal antibodies of lymphocyte subsets present in B-enriched suspensions.

B lymphocyte enriched suspensions isolated by E rosette depletion (E-cells) or by nylon fiber adherence (adherent cells) were identified by their cellular composition using different T and B cell markers (SIg,E receptor, T3, T4, T8 and Ia-like antigens). The cells were isolated from peripheral blood both of healthy donors and uremic dialysis patients. A variable proportion of non-B cells was found in some preparations. This contaminant was represented mainly by Null cells in E-lymphocyte suspensions and by T cells in the adherent population. Contaminating T lymphocytes were most frequently found in adherent cell preparations from uremic individuals and appeared to be an heterogeneous population including variable proportions of T4, T8 and Ia positive T cells. A significant increase of T8+ cells and a decrease of the ratio T4/T8 was seen among adherent T cells as compared to the normal distribution among T peripheral lymphocytes.

Antibodies, Monoclonal↗
PubMed1981

Properdin factor B polymorphism in continental Italy and Sardinia.

A sample of healthy unrelated individuals (882 from Continental Italy and Sicily, and 139 from Sardinia) were typed for HLA and Bf polymorphisms. Bf gene frequencies in Continental Italy and Sicily show an intermediate position among European populations, with Lapps on one side and Basques on the other side; while a very peculiar pattern is observed among Sardinians, with an impressive similarity with French Basques and with the highest F1 gene frequency so far observed. The HLA:Bf gametic associations in Italy and Sardinia are also reported, which confirm the different ethnic background of these populations.

Complement Factor B↗
PubMed1981

Modulation of expression of HLA components at the cell surface induced by anti-beta 2m reagents.

Antibodies against lymphocytes surface components are able to rearrange profoundly the topography of the cell membrane with a differential modulation of surface antigens. Of particular interest is the effect of anti-beta 2m reagents, which are able to suppress completely the reactivity of epitopes carried by the two chains of the ABC dimers, while th expressivity of other antigens, such as DR, is significantly increased. These results have been obtained with immunoradiobinding under a variety of conditions, thus confirming the validity of the "bb" (beta 2m blanketing) test.

Animals↗
PubMed1981

HLA antigens in juvenile dermatitis herpetiformis.

The incidence of histocompatibility antigens HLA-A, B, C, DR was studied in 32 Italian children with dermatitis herpetiformis. A significantly increased relative risk was found for B8 (R.R.=6.2), which was present in 50% of the patients as against 14% of the controls and for DR3 (R.R.=11.7), present in 69% of the patients as against 16%. DR7 also appeared to be increased, but only among DR3-negative patients. There was no significant difference in the incidence of DR3 between children with abnormal and normal jejunal biopsy, though there does seem to be a difference in expressivity of the intestinal involvement between DR3 apparent homozygous, DR3 heterozygous and DR3-negative patients.

Adolescent↗
PubMed1979

A new case of gamma heavy chain disease: clinical, immunochemical and structural characterization.

A new case of gamma heavy chain disease (gamma HCD) is described in a 77-year-old woman. The serum and urine contain an M-component and electrophoretic, antigenic and ultracentrifugal properties resembling those of the Fc fragment of IgG globulin. Analysis on SDS-polyacrylamide gel electrophoresis and ultracentrifugal studies show that gamma HCD portein is present in the serum as a dimer with a molecular weight of 58,000 daltons. Analysis of isotypic and allotypic markers along with the structural studies show that this HCD protein belongs to the IgG subclass and that deletion includes the total VH and CH1 regions with sequence starting at residue 225 in the middle of the hinge region.

Aged↗
PubMedDate not supplied

3,3',5'-Triiodothyronine concentrations in amniotic fluid at different stages of pregnancy.

Since it is feasible to detect reverse T3 (rT3) in amniotic fluid, we investigated the possibility as to whether measurements of amniotic rT3 could be useful in diagnosing fetal hypothyroidism during pregnancy. In 55 amniotic fluid samples, obtained at different stages of pregnancy, we have documented increasing concentrations of this hormone. The results obtained are conflicting with previous reports. The reason for this discrepancy is not clear, however methodological differences in rT3 determination should be taken in account. The large scatter of rT3 values in amniotic fluid suggests that the diagnosis of neonatal hypothyroidism based on measurement of rT3 may require caution.

Amniotic Fluid↗