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Biomedical subjects

A Marchi

Publications and source records attributed to A Marchi.

At least 73 records · Page 4Linked to original sources
PubMed1982

The longitudinal differentiation produced by photo-oxidation and acridine-orange staining in eukaryote chromosomes: role and involvement of DNA base composition.

Photo-oxidation and staining with acridine-orange result in a longitudinal green/orange-red/brown-red color differentiation in fixed chromosomes of Drosophila melanogaster, D. virilis, Culiseta longiareolata, and Mus musculus. Such a result has been correlated with specific DNA base sequences situated in specific chromosomal areas. In fact, given the known base composition of satellite DNA's in three of the species we studied, a correspondence seems to exist between molecular hybridization in situ of AT-rich satellite DNA's and the location of specific stain reactions in specific chromosome regions. Moreover, our results support previous findings suggesting preferential guanine destruction as a consequence of photo-oxidation.

Acridine Orange↗
PubMed1981

Long-term survival in childhood acute lymphocytic leukemia in Italy.

Among 727 children with acute lymphocytic leukemia (ALL) observed at eight pediatric clinics in Italy in the years 1967-1974, 200 (27.5%) survived for more than five years after diagnosis. The proportion of long-term survivors rose significantly during the years 1970-1974 when aggressive therapeutic programs with curative intent were uniformly adopted in Italy (19.8% vs. 29.4%; P less than 0.05). Clinical and laboratory data at diagnosis of the 200 long-term survivors were analyzed and compared with that of the 527 nonsurvivors. We found that, besides a leukocyte count greater than 50,000 cells/mm3, other factors such as early central nervous system CNS leukemia and the presence of mediastinal mass were predictive of a poorer prognosis for long-term survival. Life-table analysis revealed that the chance of long-term survival was significantly higher in those children who have survived for five years without relapse (82.9% vs. 24.1%; P less than 0.01). Although late initial relapse is always possible, if a child with ALL remains in continuous complete remission for at least nine years, it is likely that the patient is cured.

Adolescent↗
PubMed1981

Identification of chromosome markers in interphase nuclei.

The chromosome complement of the mosquito Cuilseta longiareolata (2n=6) reveals distinguishable centromeric regions and one telomere of the Y chromosome by using light-induced differentiation and autoradiographic techniques in mitotic and premeiotic interphase nuclei. The localization of these cytological markers and their spatial relationships appear to be very similar in the two types of nuclei and suggest an interphase arrangement where centromeric regions are clustered together in a chromocenter like structure, close to the nuclear membrane, with the telomeres lying on the opposite pole of the nucleus.

Animals↗
PubMed1980

Oxygen and the photodynamic action of methylene blue on fixed eukaryotic chromosomes.

In aerobic conditions, visible light irradiation of fixed eukariotic chromosomes in dilute solutions of dyes dramatically alters chromosomal structure. Our results indirectly suggest that singlet oxygen, an electronically excited and therefore reactive form of oxygen, which is produced by visible light in the presence of methylene blue, may be responsible for chromosomal alteration.

Animals↗
PubMed1978

Iron kinetics and erythropoiesis in Fanconi's anaemia.

Ferrokinetic studies were carried out in 4 patients with Fanconi's anaemia (FA). Experimental data were analysed by means of a mathematical model of iron kinetics in order to obtain a quantitative assessment of effective and ineffective erythropoietic activity, mean red cell lifespan, and non-erythroid iron turnover. The major pathogenetic mechanism of the anaemia appeared to be relative marrow failure, i.e. a reduction in the proliferative capacity of the erythroid marrow. The role of ineffective erythropoiesis was of minor importance. On the basis of the results obtained both the pathogenesis and the natural course of the disease are discussed.

Adolescent↗
PubMed1978

Cell cycle and DNA synthesis in the mosquito Aedes aegypti.

Chronology of the cell cycle has been determined for brain cells in Aedes aegypti (L.) larvae by autoradiography. The time of the cell cycle is approximately 10 h and 30 min. Areas of late DNA synthesis in metaphase chromosomes were localized mainly on the female determining (= m) chromosome of the sex pair. Correlations between late replication patterns and C-banding are discussed.

Aedes↗
PubMed1976

Karotype, DNA replication and origin of sex chromosomes in Anopheles atroparvus.

Anopheles atroparvus has two pairs of autosomes similar in length and morphology and two sex chromosomes with equal, heterochromatic, late replicating long arms with homologous C-, G-, and Q-bands. The short arm of the Y is shorter than that of the X and both are euchromatic. The mean number of chiasmata per cell in the male is 3.2. During mitosis there is a high grade of somatic pairing but X and Y, which form a heteropycnotic mass in the interphase nucleus, have a differential behaviour. The chronology of DNA replication was studied in spermatogonia and brain cells by autoradiography. It is hypothesized that the present sex chromosomes of A. atroparvus evolved by accumulation of sex determining factors and gene deterioration resulting in heterochromatinization of the long arms, followed by structural rearrangements.--The homology of the two sex chromosomes requires limited dosage compensation which is achieved either as in Drosophila by modifier genes or by accumulation on the short arm of the X, only of female determining factors which do not require dosage compensation.

Animals↗
PubMed1975

Rapidly reversible depression of delayed hypersensitivity in two children with visceral leishmaniasis.

Two cases of visceral leishmaniasis in children are described. In both "in vitro" lymphocyte response to mitogens and allogeneic cells was initially markedly depressed, but returned to normal within a few days after six days of treatment with N-methylglucamine antimonate; in one the candidin skin test reverted from negative to positive after treatment and in the other a circulating serum factor was found which strongly inhibited phytohemagglutinin--and mixed--responsiveness of normal lymphocytes, but disappeared after therapy.

Amino Sugars↗