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Biomedical subjects

A Bonati

Publications and source records attributed to A Bonati.

At least 37 records · Page 2Linked to original sources
PubMed1992

T-cell receptor beta-chain gene rearrangement and expression during human thymic ontogenesis.

T-cell receptor (TCR) beta-chain proteins appear early (approximately 15th week of gestation) during human thymic ontogenesis. These beta-chain proteins, which appear before terminal deoxynucleotidyl transferase (TdT), could be an expression of a fully rearranged (V-D-J), incompletely rearranged (D-J), or germline TCR beta-chain gene. The aims of this study, performed from the 15th week onward, were the following: (1) to investigate whether or not TCR beta gene rearranges at an early stage during human thymic ontogenesis; (2) to investigate whether complete presumptive functional (1.3 kb) TCR beta gene transcript is present at these early stages of development, or if incomplete (1 kb) or germ-line (1.1 kb) transcripts are expressed; (3) to examine the phenotype of TCR beta-chain+ cells with two-color fluorescence using monoclonal antibody (MoAb) beta F1 and MoAbs that recognize CD1, CD2, CD3, CD4, CD8, CD5, and CD7 antigens (rabbit anti-calf TdT antiserum was used to detect TdT); and (4) to demonstrate whether or not beta gene N-diversity regions are detectable as early as the 15th week and whether or not N-nucleotide insertions correlate to TdT expression. Fifteen- to 22-week fetal thymuses and pediatric thymuses were investigated. We demonstrated that TCR beta-chain gene rearranged as early as the 15th week in human thymus and that a complete functional TCR beta gene transcript was expressed at these early stages of human development. No other analyses to date have investigated TCR beta gene expression in early human thymus using molecular biology techniques. No significant differences were detectable between phenotypic analysis of fetal and pediatric samples, except for TdT expression, which appeared after the 20th week. Essentially all mCD3+ (OKT3+) cells were beta-chain+ at the different weeks investigated. A significant percentage of CD1+ cells were beta-chain+, and the percentage increased along with the age of development. After the 20th week, we identified three main populations: TdT+, cCD3+, beta F-(early thymic precursors); TdT+, CD1+, beta F1+ (intermediate maturity cortical thymocytes); and TdT-, mCD3+, beta F1++ (mature medullary thymocytes). Given these values, we may consider beta-chain expression an ordered process. beta gene N-nucleotide insertions were correlated to TdT expression, since N-regions increased considerably after the 20th week. A further increase of N-nucleotide insertions was detected from the 22nd week to the 32nd week.

Age Factors↗
PubMed1991

How and why should we standardize phytopharmaceutical drugs for clinical validation?

Standardized extracts are needed to carry out reliable clinical trials. The standardization of an extract does not include only a whole of analytical controls: it requires also a thorough description of the starting drug and of the whole extraction process, both basic items for the constancy of the quality of an extract. Another not minor aspect in the standardization of an extract is its nomenclature which must include all the necessary data for a clear definition (drug, physical state, solvent of extraction, composition) of the extract itself. Two examples of standardization are described, one concerning an extract whose therapeutical active constituents are known (anthocyanoside complex of Vaccinium myrtillus) and the other concerning an extract whose constituents must be regarded as chemical markers (Pygeum africamum extract).

Plant Extracts↗
PubMed1990

Hematopoietic growth factors: in vitro and in vivo studies in bone marrow transplantation.

The results of in vivo studies conducted with colony-stimulating factors (CSFs) in autologous bone marrow transplantation (ABMT) are summarized. Our own data obtained from in vitro models dealing with the use and possible applications of CSFs in ABMT are reported. In particular, we show data concerning: 1) the use of interleukin 3, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 1 to expand hematopoietic progenitor cell growth in the early phase of ABMT; 2) in vitro marrow purging with Mafosfamide and GM-CSF in chronic myelogenous leukemia; and 3) growth requirements of MY10-derived leukemic colony-forming units. The use of CSFs, alone or in combination, may provide us with new strategic approaches for the treatment of acute and chronic leukemias. CSFs in combination with chemotherapeutic agents are very promising agents for purging marrow prior to ABMT.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Terminal deoxynucleotidyl transferase-positive B cell precursors in fetal lymph nodes and extrahemopoietic tissues.

Terminal deoxynucleotidyl transferase (TdT)-positive B cell precursors populate fetal lymph nodes (LN) of mid-term (16th-22th week) fetuses. These cells have a B cell phenotype (HLA-DR, CD45R, CD22, mu) and lack mature differentiation antigens (CD1c, CD20, L26). TdT+ cells are also present in the extranodal mesenteric mesenchyme, pancreas and LN primordia. Extranodal TdT+ cells are found among proliferating (i.e. Ki-67+) B cells and lack leukocyte function-associated antigen (LFA-1) and HLA-DQ; these latter molecules are acquired by nodal TdT+ elements. Adult LN, adult and fetal spleen contain less TdT+ cells than fetal LN. The fetal LN contains the full range of the B cell differentiation compartment, from the TdT+ precursor cell to the mature B lymphocyte.

Antigens, Surface↗
PubMed1989

Discordant expression of terminal transferase and T cell receptor beta chain in fetal and pediatric thymocytes.

Human thymuses at different ages of development were analyzed for TdT+/beta F1+ double-stained cells. beta F1 is a mAb which recognizes a "hidden" framework determinant on the beta chain of the T cell receptor (TCR). We have found that TCR beta chains appear early during thymic ontogenesis and are detectable by 15 weeks of gestation in cells that are TdT-. Paradoxically, the immature CD2- large thymic blasts in late fetal development and in infants are TdT+ but beta chain negative. These data are compatible with the notion that TdT acts as somatic mutagen on TCR beta genes starting only after 20 weeks of gestation. The beta chain proteins which appear early during thymic ontogenesis might reflect expression of incompletely rearranged (DJ), unrearranged, or fully rearranged TCR beta genes in an early wave of thymocyte clonal (beta) diversification, that is, in contrast to later development, independent of TdT.

Age Factors↗
PubMed1989

Philadelphia-positive chronic myelogenous leukemia with typical bcr/abl molecular features and atypical, prolonged survival.

Despite the major breakthrough in the knowledge of the molecular events underlying the t(9;22) translocation, still no consistent data have been found on the evolution of Ph1 positive CML from the chronic to the accelerated or blastic phase of the disease. In most patients in fact the bcr/abl rearrangements are identical both in chronic phase and in blast crisis, and overall differences in chronic phase duration, related to different location of breakpoints inside the bcr region, were found to be marginal. We approached this problem by studying the molecular features of the bcr/abl abnormality in rare CML patients with very long, atypical chronic phase. The three patients studied, whose chronic phase duration is 17, 19, and 21 years, respectively, have typical genomic bcr rearrangements, and two of them show, hybridizing Northern blots to c-abl, the 8.5 kb mRNA, as that typically present in CML. It seems that genomic alterations within bcr and abl cannot account, alone, for the duration of the chronic phase of Ph1 positive CML and those quantitative and/or qualitative alterations of the p210 bcr/abl protein, unluckily awkward to prove, might be responsible for the atypical clinical features of these CML long survivors.

Adult↗
PubMed1986

Progression of a myelodysplastic syndrome to pre-B acute lymphoblastic leukaemia with unusual phenotype.

This study shows the progression of a myelodysplastic syndrome (MDS) to pre-B acute lymphoblastic leukaemia (ALL) with an unusual phenotype. On diagnosis of leukaemia bone-marrow mononuclear cells were labelled with murine monoclonal antibodies HLA-DR, VIL-A1 (CALLA), 3813, VIM-D5 and with a rabbit antiserum to TdT using a double colour indirect immunofluorescence technique. In addition simultaneous detection of cytoplasmic mu chains (Cy mu) and of TdT was carried out and a direct immunofluorescence analysis for surface membrane immunoglobulins (SmIg) was performed. Two main populations were present: the major one being HLA-DR+, Cy mu+, VIM-D5+, TdT-, CALLA-, SmIg-; the minor one HLA-DR+, Cy mu+, VIM-D5-, TdT+, CALLA-, SmIg-. The progression of our case to acute leukaemia with a population of leukaemic cells each of which demonstrated features of lymphoid and myeloid cells suggests that MDS would originate at the pluripotential stem cell level.

Acute Disease↗
PubMed1985

Leu-7-positive cells with monocyte phenotype show different ultrastructural features in comparison to Leu-7-positive cells with T-cell phenotype.

The ultrastructural features of the Leu-7-positive - Leu-M3-positive cell subpopulation and the Leu-7-positive - Leu-4-positive cell subpopulation were characterized and compared using immunogold-immunoperoxidase double labelling with immunoelectron microscopy. The majority of Leu-7-positive cells coexpressed a monocyte phenotype and showed an ultrastructural pattern specific for functional natural killer (NK) cells, i.e. a low nuclear/cytoplasmic (N/C) ratio, an irregular outline, many cytoplasmic organelles and electron-dense granules. In contrast, only a minority of Leu-7-positive cells coexpressed a T phenotype, and these were characterized by a high N/C ratio, an even surface and the absence of electron-dense granules. Thus, Leu-7-positive - Leu-4-positive cells may by an immature form of NK cells, and Leu-7-positive - Leu-4-positive and Leu-7-positive - Leu-M3-positive cell subpopulations may represent different stages of Leu-7-positive cell differentiation.

Antibodies, Monoclonal↗
PubMed1985

Detection of the common acute lymphoblastic leukaemia antigen (CALLA) on B cells from human fetal tissues. A multiple phenotypic characterization.

Fetal bone marrow liver and spleen of gestational age 15-20 weeks contain CALLA+, HLA-DR+ lymphoid cells. We show that a proportion of them expresses surface membrane immunoglobulins (SIg) as well as B cell differentiation antigens. A multiple phenotypic analysis reveals that CALLA+ fetal B cells are: HLA-DR+, SIg+, FMC8+, BA1+, Y29.55+ or Y29.55-, B2+, TdT-. Tissue specific phenotypic differences concern the expression of B7 and HLA-DC on spleen but not on bone marrow B cells. This study indicates that the distribution of the CALL antigen across the B cell committed lineage is much wider in fetal than neonatal life since CALLA+B cells have not yet been detected in bone marrow and peripheral blood of normal infants and adults. In addition, the interpretation of our phenotypic data suggest that fetal bone marrow B cells are more immature than those present in the spleen, thus, further supporting the evidence that the bone marrow is the organ of B cell lymphopoiesis.

Antigens, Neoplasm↗
PubMed1984

The fine structure of HNK-1 (Leu7) positive cells. A study using an immunoperoxidase technique.

The ultrastructural characteristics of HNK-1 (Leu7) positive cells, visualized with a peroxidase labelled anti-mouse IgM serum, were analysed. Our investigation demonstrates: 1) the majority of Leu7 positive cells has a low nuclear/cytoplasmic ratio (N/C), an irregular outline, a well developed smooth endoplasmic reticulum, parallel tubular arrays (PTA) and electron dense granules; 2) the minority of Leu7 positive cells has a high N/C, regular profiles and lacks electron dense granules. The presence of two distinct ultrastructural patterns within Leu7 positive cells may represent: 1) the expression of subsequent stages of cell differentiation; 2) two distinct Leu7 positive cell subpopulations.

Antibodies, Monoclonal↗
PubMed1984

Phenotype of the terminal transferase-positive cells in human foetal liver and bone-marrow: analysis with monoclonal antibodies.

Liver and bone-marrow of 20 human foetuses between 15th and 20th week of gestational age were examined. Mononuclear cells were labelled with murine monoclonal antibodies to reveal surface antigens and with a rabbit antiserum to TdT for the detection of the nuclear enzyme, using a double colour indirect immunofluorescence technique. The results have revealed that TdT+ cells express the phenotype of B cell precursors HLA-DR+, CALLA+, FMC8+, LEU-1-, LEU-5-, LEU-9-. It suggests that foetal liver and bone-marrow have an active function in B-lymphopoiesis in humans. The involvement of TdT in the process of B-cell immunological acquisition is uncertain because only humans and Xenopus embryos, among the species examined, express TdT outside the thymus during ontogenesis.

Adolescent↗
PubMed1983

Ph1-positive acute myelocytic leukemia with high TdT levels.

The authors have determined TdT levels in a case of Ph1-positive AML. Peripheral blood cells and bone marrow cells taken during the various phases of the disease were examined. Liquor cells were analyzed when symptomatic central nervous system involvement occurred. High TdT levels were found in all of the phases of the disease including the liquor. TdT eluted at various isoelectric points indicating a shifting of the activity to greater molarity during progress of the disease. Two different forms of TdT were present in the liquor. The authors speculate about the existence of a relation between TdT levels and Ph1-positive leukemia. They point out the importance of TdT levels as functional criterion of remission in acute leukemia. Finally, the existence of different forms of TdT could be the expression of a clonal selection caused by therapy or of a spontaneous clonal competition.

Adolescent↗
PubMed1983

Terminal deoxynucleotidyl transferase (TdT) in human foetuses. An immunofluorescent and biochemical study.

The liver, bone marrow and cord blood of 30 human foetuses between the 15th and 21st weeks of gestational age were examined. Liver suspensions were investigated both by immunofluorescent and biochemical assay; cord blood suspensions and bone marrow touches with immunofluorescent assay. The results indicate the existence of a few TdT+ cells in the liver, cord blood and bone marrow of human foetuses in the ages studied. The peaks for each organ were: 15 +/- 1.60 (mean +/- SD) TdT+ cells in the liver, 12 +/- 2 in the bone marrow and 18 +/- 2.83 in the cord blood. In all the organs TdT+ cells decrease in the later weeks. In the liver, the results of the immunofluorescent assay were confirmed by the biochemical activity.

Bone Marrow↗