Search PubMed⌕ Search

Biomedical subjects

G Torelli

Publications and source records attributed to G Torelli.

At least 163 records · Page 9Linked to original sources
PubMed1981

Sequence complexity and diversity of polyadenylated RNA molecules of human normal resting, PHA-stimulated and leukemic lymphocytes.

The abundance and complexity of total poly(A)+RNA of human normal unstimulated lymphocytes, PHA-stimulated and leukemic lymphocytes were examined using the cDNA-poly(A)+ RNA hybridization technique. It was found that in both PHA-stimulated and leukemic lymphocytes the complexity of total poly(A)+RNA is strongly reduced in respect to normal unstimulated lymphocytes. The differences is due to a small portion, by weight, of high complexity sequences, suggesting the involvement or nuclear, not necessarily transcriptional, events. Moreover the heterologous hybridizations show that: 1) in PHA-stimulated lymphocytes there is a set of highly abundant sequences which are represented in normal and leukemic lymphocytes at a very reduced rate; 2) the sequences abundant in normal unstimulated lymphocytes are less represented in leukemic lymphocytes; the converse also is true, but at a lower extent. On the basis of available data, it is suggested that the observed changes in the abundance pattern of PHA-stimulated lymphocytes may be related mainly to a difference in the half-life of the mRNAs, while those of leukemic lymphocytes require some transcriptional or post-transcriptional nuclear event.

Base Sequence↗
PubMed1981

Presence of a highly repetitive and widely dispersed DNA sequence in the human genome.

A genomic DNA library consisting of human DNA fragments about 18 kilobases long cloned in a bacteriophage lambda vector was found to contain a specific repeated DNA segment. The repeated sequence is present in greater than 95% of the genomic library, and selected clones contain at least two copies of the sequence. Our experiments indicate that this highly repetitive sequence (approximately 400,000 copies per haploid genome) is widely distributed in the human genome and is represented in the cytoplasmic polysomal mRNA. This sequence is homologous to the 300-base-pair Alu repeat family, the predominant repeat sequence in man.

Cloning, Molecular↗
PubMed1981

The radiologic "Target sign" of septic pulmonary embolism in a case of acute myelogenous leukemia.

The authors report the appearance of septic pulmonary embolism in a case of acute myelogenous leukemia. The pulmonary lesions are characterized radiographically by the uncommon appearance of central densities suspended within thin-walled pseudocystic air spaces. A possible pathogenic mechanism explaining these radiographic findings is discussed. Such images must be distinguished from those of a fungus ball or tuberculous cavities.

Adolescent↗
PubMed1979

[Clinico-immunological study of 6 cases of Behçet's disease].

6 cases of Behçet's disease are reported. Diagnosis was particularly arduous because the typical triad of symptoms (oral aphthae, genital ulcers, uveitis) was masked by secondary disturbances in other organs and systems. Immunology confirmed the presence in these patients of changes in various in vivo and in vitro tests and particularly interesting was the aspecific cutaneous hypersensitivity seen in 5 cases and enhanced lymphocyte blastic transformation. This was seen spontaneously and following PHA. On the basis of the outcome of the studies carried out and the literature data, the possibility that Behçet's disease may contain immunological changes and changes in the mechanisms that regulate quinine, complement and clotting activation is suggested. Therapeutically, confirmation was obtained of the effectiveness, at least temporarily, of corticosteroid treatment and antilymphocyte globulin was experimented for the first time in these patients. This might be used to replace the immune depressant antiblastic substances already successfully employed in patients with Behçet's disease.

Adolescent↗
PubMed1979

Kinetics of hybridization to human DNA of heterogeneous nuclear RNA isolated from normal human lymphoblasts and acute leukemia blast cells.

Heterogeneous nuclear RNA was extracted from normal PHA-stimulated human lymphocytes and acute myeloid leukemia blast cells. Experiments were performed to determine the hybridization kinetics of these RNA's to human DNA. The best least squares solutions indicate in the hybridization reaction of both normal and leukemic RNA two main components. For leukemic cell RNA the rate constants of both components were significantly different from that of normal cell RNA. In particular, the difference between the rate constants of the second lower component suggests that the slowly hybridizing sequences in leukemic cell RNA have a degree of repetition higher than of the corresponding sequences of normal cell RNA.

Base Sequence↗
PubMed1979

Reassociation kinetics of the DNA of human acute leukemia cells.

Human DNA isolated from normal phytohaemagglutinin-stimulated human lymphocytes and from acute leukemia blast cells have been studied by renaturation techniques using hydroxyapatite binding and DNA hyperchromism. In the leukemic genome, the unique sequences account for 62% of the genome of leukemic DNA. Repetitive sequences may be subdivided into at least three fractions: (a) foldback sequences, which represent 5% of the genome; (b) sequences with high repetition frequency (3. 10(4) times on the average), which represent 12% of the genome; (c) sequences with low repetition frequency (10 times on the average), which represent 16% of the genome. The average length of the repetitive sequences is evaluated to be between 200 and 500 nucleotides. There are at least two patterns of interspersion of repetitive sequences with unique sequences of different length: short (about 2000 nucleotides on average) and long (not defined). The results of our experiments on DNA from normal phytohaemagglutinin-stimulated human lymphocytes are in close agreement with those reported by other authors studying different types of human cells. The human leukemic DNA, as far as the parameters that have been studied, does not significantly differ from normal human DNA.

Acute Disease↗
PubMed1979

A method for the in situ measurement of the electrical quantities in frog skin.

A method allowing the measurement of the electrical quantities related to the physiological functions of the frog skin in situ is presented. The method allows the performance of several experiments on the same pithed animal, which remains alive for a number of days. The preparation is very stable, and the electrical potential difference and short-circuit current values are higher than in isolated skin. The theory of measurement and the possible systematic errors are discussed. The possibilities of the method are evaluated on comparing the pH and temperature dependence of the electrical quantities in situ with previous measurements on isolated skin.

Animals↗
PubMed1977

Immunological assay of double-helical segments in RNA fractions of different molecular size extracted from acute myeloid leukemia blast cells.

Whole-cell RNA, extracted from acute myeloid leukemia blast cells, was fractionated by sedimentation through sucrose gradients. The proportion of double-helical segments present in each fraction was then determined by a quantitative microcomplement fixation assay that specifically measures double-helical RNA. Sizable amounts of double-helical segments were detected in all fractions of cellular RNA corresponding to S values higher than approximately 20. In all cell populations examined the highest proportion of double-helical segments was found in RNA fractions sedimenting faster then the 45 S ribosomal precursors RNA, i.e., in fractions including only heterogeneous nuclear RNA.

Antibody Specificity↗
PubMed1977

Hemoglobin-oxygen equilibrium at different hemoglobin and 2,3-diphosphoglycerate concentrations.

Hemoglobin-oxygen equilibrium curves at constant pH, ionic strength, and temperature were determined (a) on 2,3-DPG-free solutions at various hemoglobin (Hb) concentrations, (b) on solutions at various Hb concentrations but constant 2,3-DPG/Hb molar ratio, (c) on solutions at constant hemoglobin concentration but various 2,3-DPG/Hb molar ratios, and (d) on hemolysates at various Hb concentrations. Under all conditions the shape of the equilibrium curve was the same (n = 2.62 +/- 0.04, 33 experiments). Half-saturation pressure (P 1/2) did not change with increasing Hb concentration in case (a), whereas P 1/2 was linearly related to Hb concentration in case (b). In case (c) at 200 g/l Hb, P 1/2 increased sharply as 2,3-DPG/Hb molar ratio increased up to 0.4 but changed little as the ratio was further increased up to 1.5. This behavior is very different from that observed in diluted (5 g/l) solutions. P 1/2 of the hemolysates was also linearly related to Hb concentration but the slope was about twice that for case (b). These results cannot be explained by linked function theory or by a dimer-tetramer equilibrium. It is suggested that intermolecular interactions in the presence of organic phosphates may be responsible for the observed changes in Hb affinity for oxygen.

Dextrans↗
PubMed1976

Accumulation of giant heterogeneous RNA molecules in acute myeloid leukemia blast cells.

Time course and "chase" experiments showed that, after incubation of acute myeloid leukemia blast cells with a labeled RNA precursor, a large proportion of radioactivity remained associated with RNA molecules larger than 45 S even after several hr. Double-labeling experiments with [5-3H]uridine and [methyl-14C]methionine indicated that unmethylated giant heterogeneous RNA larger than 45 S is processed much more slowly than the 45 S ribosomal precursor, so that relatively large amounts of fairly stable RNA of the former class accumulate in the cell. The measurement of labeled giant heterogeneous RNA molecules bound to polyuridylate-fiberglass filters showed that molecules carrying polyadenylate segments seemingly turn over faster than those lacking polyadenylate.

Dactinomycin↗
PubMed1975

Sodium chloride reflection coefficient in rabbit gall bladder.

By means of the Kedem-Katchalsky thermodynamic description of active transport, a relationship has been derived between the apparent reflection coefficient and the Staverman reflection coefficient for passive transport of a solute which is both actively and passively transported. The relationship between volumetric flow and its driving forces, containing the Staverman reflection coefficient, was tested for sodium chloride in rabbit gall bladder and the reflection coefficient was evaluated.

Animals↗