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Biomedical subjects

G Santini

Publications and source records attributed to G Santini.

At least 19 recordsLinked to original sources
PubMed1979

Lack of spontaneous sister chromatid exchanges in somatic cells of Drosophila melanogaster.

Neural ganglia of wild type third-instar larvae of Drosophila melanogaster were incubated for 13 hours at various concentrations of BUdR (1, 3, 9, 27 micrograms/ml). Metaphases were collected with colchicine, stained with Hoechst 33258, and scored under a fluorescence microscope. Metaphases in which the sister chromatids were clearly differentiated were scored for the presence of sister-chromatid exchanges (SCEs). At the lowest concentration of BUdR (1 microgram/ml), no SCEs were observed in either male or female neuroblasts. The SCEs were found at the higher concentrations of BUdR (3, 9, And 27 micrograms/ml) and with a greater frequency in females than in males. Therefore SCEs are not a spontaneous phenomenon in D. melanogaster, but are induced by BUdR incorporated in the DNA. A striking nonrandomness was found in the distribution of SCEs along the chromosomes. More than a third of the SCEs were clustered in the junctions between euchromatin and heterochromatin. The remaining SCEs were preferentially localized within the heterochromatic regions of the X chromosome and the autosomes and primarily on the entirely heterochromatic Y chromosome.--In order to find an alternative way of measuring the frequency of SCEs in the Drosophila neuroblasts, the occurrence of double dicentric rings was studied in two stocks carrying monocentric ring-X chromosomes. One ring chromosome, C(1)TR94--2, shows a rate of dicentric ring formation corresponding to the frequency of SCEs observed in the BUdR-labelled rod chromosomes. The other ring studied, R(1)2, exhibits a frequency of SCEs higher than that observed with both C(1) TR94--2 and rod chromosomes.

Animals↗
PubMed1979

Bone marrow transplantation for severe aplastic anemia. A report of 9 cases.

9 patients with severe aplastic anemia (SAA) were treated with bone marrow transplantation (BMT). 5 were conditioned with cyclophosphamide and received and HLA-identical graft (4 patients) or a mismatched graft (1 patient): 1 rejected the graft on day 30 and died on day 34 during conditioning for a second transplant; 1 died on day 15 with acute and severe graft versus host disease (GvHD) in the absence of haemopoietic engraftment; 3 are alive and complete chimeras at 1,069, 490 and 332 days after transplantation. GvHD developed in 4 patients and was treated successfully in 3 with high dose methylprednisolone and/or antilymphocytic globulin (ALG). 4 patients were conditioned with ALG and received bone marrow from a haploidentical sibling or parent: 1 patient was refractory; 3 patients showed evidence of hematologic reconstitution, but 2 of these required a second course of ALG. 3 patients in this group are alive between 60 and 490 days; 1 patient died on day 121 of HBSAg-negative acute hepatitis.

Adolescent↗
PubMed1978

3h-actinomycin-D binding to mitotic chromosomes of Drosophila melanogaster.

The binding of 3H-AMD to the metaphase chromosomes of Drosophila melanogaster has been analyzed after two different periods of exposure to photographic emulsion. The entirely heterochromatic Y chromosome was markedly less labelled than euchromatin and other heterochromatic regions. Moreover, the few grains present on the Y chromosome were clustered in two regions, one localized in the middle Ys and the other in the proximal third of YL. This labelling pattern is not affected by removing histones with a 2-hour treatment with 2N HCl. It is suggested that the specific underlabelling of the Y chromosome reflects a peculiar AT richness.

Animals↗
PubMed1978

Lymphoid antigens on blast cells in the agranular metamorphosis of chronic myelogenous leukaemia.

Undifferentiated blasts from a Ph'-positive chronic myelogenous leukaemia (CML) in terminal metamorphosis were reacted in an indirect immunofluorescence test with antilymphocytic globulins (AHLGs), raised against cultured lymphoblasts, thoracic duct and peripheral blood lymphocytes from healthy donors. After proper myeloid and/or monocytic absorptions the AHLGs interacted strongly with the undifferentiated blasts of CML, while this was not true for parallel controls with non-lymphoid leukaemias, both acute and chronic. The intensity of fluorescence, as determined by the use of a microfluorimeter, on these agranular blasts was comparable to the positivity of lymphoid cells from acute and chonic lymphatic leukaemias. These findings lend further support to the conception of a lymphoblast-like variety of terminal blastic crisis in chronic myelogenous leukaemia.

Antigens, Surface↗
PubMed1977

Fluorescence banding techniques in the identification of sibling species of the anopheles gambiae complex.

The mitotic chromosomes of the sibling species A and B of the Anopheles gambiae complex were stained with Hoechst 33258 and examined by fluorescence microscopy. The autosomes fluoresce homogenously and similarly in both species while the sex chromosomes differ in the location and brightness of some heterochromatic blocks. These cytochemical differences allow the cytotaxonomic identification of these cryptic species.

Animals↗
PubMed1977

Mutagen specificity in the induction of chromosomal aberrations in somatic cells of Drosophila melanogaster.

The distribution of chromosomal aberrations between and within chromosomes of male D, melanogaster somatic cells after treatment with UV has been analyzed. -- Distribution of the breaks between chromosomes was largely nonrandom since we found a higher aberration frequency than that expected on the Y chromosome. Moreover, within the chromosomes the aberrations are clustered in the pericentromeric heterochromatic regions. The above distribution is compared with that of the breaks induced by X rays and methyl-methane-sulphonate (MMS) which were distributed in a different pattern.

Animals↗
PubMed1977

A to O bone marrow transplantation in severe aplastic anaemia: dynamics of blood group conversion and demonstration of early dyserythropoiesis in the engrafted marrow.

A to O bone marrow transplantation was performed in a 25-year-old male affected with severe aplastic anaemia, the donor being an HLA compatible brother. Three plasma exchanges had to be performed with an Aminco separator to remove the original and recurring anti-A isohaemagglutinins. The dynamics of O to A blood group conversion were followed by means of differential agglutination. An early wave of marked dyserythropoiesis was observed in the engrafted marrow. Mild to moderate GvHD was treated successfully with MTX, bolus high dosage 6-methylprednisolone and, at relapse, with intravenous ALG.

ABO Blood-Group System↗
PubMed1977

Peptichemio: A new oncolytic drug in combination with vincristine and prednisolone in the treatment of non-Hodgkin lymphomas.

Peptichemio, a new oncolytic drug with alkylating and antimetabolic properties was employed in combination with vincristine and 6-methylprednisolone (PVP) for the treatment of diffuse non-Hodgkin's lymphomas (NHL), stages III and IV. 52 of 66 patients who entered the PVP protocol were considered evaluable: the overall remission rate in diffuse lymphocytic poorly differentiated lymphomas (DLPD) was 56.6 and 55% in diffuse histiocytic lymphomas (DHL). Median duration of complete remission was 16 months in DLPD and 13 months in DHL. Dramatic results were obtained in "oncologic emergencies," such as mediastinal involvement and spinal cord compression. Bone marrow depression from PVP was moderate and never caused discontinuation of therapy. According to these results the PVP protocol would appear susceptible of offering a major contribution to the chemotherapy of diffuse NHL.

Alopecia↗
PubMed1976

Characterization of Drosophila heterochromatin. I. Staining and decondensation with Hoechst 33258 and quinacrine.

A number of preliminary experiments have shown that the fluorescence pattern of Hoechst 33258, as opposed to that of quinacrine, varies with the concentration of dye. The metaphase chromosomes of D. melanogaster, D. simulans, D. virilis, D. texana, D. hydei and D. ezoana have therefore been stained with two concentrations of H 33258 (0.05 and 0.5 mug/ml in phosphate buffer at pH 7) and with a single concentration of quinacrine (0.5% in absolute alcohol). The three fluorescence patterns so obtained were shown to be somewhat different in some of the species and the coincide in others. All three stainings gave an excellent longitudinal differentiation of heterochromatin while euchromatin fluoresced homogeneously. Living ganglion cells of the six species mentioned above were treated with quinacrine and H 33258. Quinacrine induced a generalized lengthening and swelling of the chromosomes and H 33258 the decondensation of specific heterochromatic regions. A correlation of the base composition of the satellite DNAs contained in the heterochromatin of the species studied with the relative fluorescence and decondensation patterns showed that: 1) the extremely fluorochrome bright areas and those decondensed are present only in species containing AT rich satellite DNA; 2) the opposite is not true since some AT-rich satellite DNAs are neither fluorochrome bright nor decondensed; 3) there is no good correspondence between Hoechst bright areas and the decondensed ones. AT richness therefore appears to be a necessary but not sufficient condition both for bright fluorescence and decondensation. Some cytological evidence suggests that similarly AT rich satellite DNAs respond differently in fluorescence and decondensation because they are bound to different chromosomal proteins. A combination of the results of fluorescence and decondensation revealed at least 14 types of heterochromatin; 4-7 of which are simultaneously present in the same species. Since closely related species (i.e. D. melanogaster and D. simulans; D. virilis and D. texana) show marked differences in the heterochromatic types they contain, it can be suggested that within the genus Drosophila qualitative variations of heterochromatin have played an important role in speciation.

Animals↗
PubMed1976

Characterization of Drosophila heterochromatin. II. C- and N-banding.

The C- and N-banding patterns of D. melanogaster, D. simulans, D. virilis, D. texana, D. ezoana and D. hydei were studied in comparison with quinacrine and Hoechst banding patterns. In all these Drosophila species the C bands correspond to the heterochromatin as revealed by the positive heteropycnosis in the prometaphase chromosomes. The N bands have the following characteristics: 1) they are always localized on the heterochromatin and generally do not correspond to the C bands; 2) they do not correspond to the nucleolar organizing regions; 3) they are inversely correlated with fluorescence, i.e., they correspond to regions which are scarcely, if at all, fluorescent after Hoechst 33258 or quinacrine staining; 4) they are localized both on regions containing AT rich satellite DNA and on those containing GC rich satellite DNA.

Animals↗
PubMed1975

Immunofluorescent diagnosis of acute lymphoblastic leukaemia.

When leukaemic lymphoblasts from acute lymphatic leukaemia were reacted with animal anti-human lymphocyte globulin (AHLG), and subsequently with the appropriate, fluorescein-isothiocyanate-conjugated antibodies, a brilliant membrane fluorescence was observed, which persisted up to 5 log titres, breaking from rings into spots at higher dilutions. The best results were obtained with fresh suspensions and incident illumination. Cross-reactions with mature and immature myeloid cells with the unabsorbed antisera could be abolished by repeated preabsorbtion of AHLG with packed leukocyte preparations from chronic and acute myeloid leukaemias. Thus, it appears that this approach is susceptible of improving the identification of leukaemic lymphoblasts, and may be extended, by means of appropriate antisera, to the acute leukaemias in general.

Animals↗