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R Piva

Publications and source records attributed to R Piva.

At least 91 records · Page 5Linked to original sources
PubMed1987

Regulation of the expression of class II genes of the human major histocompatibility complex in tumor cells.

The control of expression of human class II MHC genes has been studied in lymphoid and melanoma cells. Specific unmethylation of all restriction sites nearby the promoter regions has been detected in all cell lines and tissues studied, irrespective of their ability to express class II MHC products. The main functional role of DNA methylation appears, on the contrary, to be the regulation of a fraction of the nucleotide polymorphism of class II MHC genes. Constitutive expression of these genes can be modified by recombinant IFN-gamma and by the demethylating agent 5-azacytidine. Both the modifiers differentially regulate the levels of class II MHC and invariant chain products. In melanoma cells IFN-gamma derepresses transcription of a 1.2-Kb HLA-DR alpha mRNA, but does not affect the levels of a 0.8-Kb HLA-DR alpha specific mRNA. These molecular changes are triggered by IFN-gamma through a protein-synthesis-dependent pathway.

Azacitidine↗
PubMed1986

Human leukemic K562 cells: suppression of hemoglobin accumulation by a monoclonal antibody to human transferrin receptor.

The receptor for transferrin plays an important role both in tumor cell growth and in hemoglobin synthesis. In this paper, we demonstrate that the monoclonal antibody 42/6 to human transferrin receptor inhibits iron uptake in the human leukemic K562 cell line and suppresses hemoglobin accumulation in K562 cells induced to erythroid differentiation by butyric acid. In contrast, only slight inhibitory effects were observed on cell proliferation of both uninduced and erythroid-induced K562 cells treated with the 42/6 monoclonal antibody. In addition, the 42/6 monoclonal antibody to human transferrin receptor does not inhibit butyric acid-induced accumulation of gamma-globin mRNA. The effect of the 42/6 monoclonal antibody on hemoglobin synthesis appears to be restricted to human cell lines, as murine Friend erythroleukemic cells undergo erythroid differentiation when cultured in the presence of hexamethylenebisacetamide plus the 42/6 monoclonal antibody. The findings reported in this paper suggest (a) a dissociation of iron transport and accumulation of heme molecules from the expression of globin genes and (b) a different requirement of iron uptake by different iron-dependent functions such as cell proliferation and hemoglobin expression.

Antibodies, Monoclonal↗
PubMed1986

Methylation and expression of c-myc and c-abl oncogenes in human leukemic K562 cells before and after treatment with 5-azacytidine.

The correlation between expression and extent of DNA methylation of c-myc and c-abl oncogenes has been investigated in the human leukemic K-562 cell line before and after 5-azacytidine-mediated erythroid induction. RNA accumulation was analyzed by cytoplasmic dot hybridization and DNA methylation by using HpaII and MspI endonucleases, which differently cleave the CCGG sequence depending on cytosine methylation. Both the oncogenes are expressed in uninduced cells; however, whereas the c-myc expression does not change following 5-azacytidine treatment, the c-abl expression sharply decreases. The HpaII pattern shows that the c-myc DNA region is undermethylated and that the c-abl gene is hypermethylated both before and after the erythroid induction. Nevertheless, in both the genes 5-azacytidine produces variations in the MspI pattern compatible with mCmCGG to CmCGG demethylations.

Azacitidine↗
PubMed1985

Efficient cell proliferation and predominant accumulation of epsilon-globin mRNA in human leukemic K562 cells which produce mostly Hb Gower 1.

Long-term cultures of K562(S) cells in 50-75 microM hemin allow the selection of 'hemin-resistant' K562 cells together with cells which proliferate efficiently while fully induced to express the human embryonic globin genes, as the hemoglobin Gower 1 (zeta 2 epsilon 2) is the predominant hemoglobin produced. Our experiments demonstrate that these K562 cells accumulate mostly epsilon-globin mRNA (epsilon-globin mRNA/gamma-globin mRNA = 2.9) suggesting that the control of hemoglobin expression is at a pretranslational level.

Cell Division↗
PubMed1984

Human leukemia K562 cells: relationship between hemin-mediated erythroid induction, cell proliferation and expression of c-abl and c-myc oncogenes.

We have studied the expression of the c-myc and c-abl oncogenes in two human leukemic K562 cell lines which do express hemoglobin genes retaining a differential rate of cell proliferation. Our data indicate that in hemin-induced K562(S) cells the expression of c-abl oncogene decreases and appears to be related to a decrease in the proliferation capacity rather than to the activation of differentiated functions. The K562(hC) cell line, which produces large amounts of Hb Gower 1 retaining an efficient rate of cell proliferation, expresses indeed the c-abl oncogene at high level.

Cell Division↗
PubMed1984

Right oblique subxiphoid view for two-dimensional echocardiographic visualization of the right ventricle in congenital heart disease.

Two-dimensional echocardiography in the right oblique subxiphoid view (ROSV) was used to visualize all right ventricular components in 351 patients younger than 2 years of age (100 normal and 251 with various types of congenital heart disease). The ROSV, which is anterior and parallel to the ventricular septum, displays all right-sided cardiac components, the left atrium and the aorta. This view provided the correct diagnosis in patients with pulmonary stenosis or atresia with intact ventricular septum, Ebstein's anomaly, tricuspid atresia, infundibular ventricular septal defect, tetralogy of Fallot and truncus arteriosus. In all patients studied with the ROSV, an excellent definition of morphologic characteristics, equivalent to that in the right oblique axial angiocardiographic view, was achieved. The ROSV should be used routinely to delineate the right ventricular anatomy in all infants with congenital heart disease.

Ebstein Anomaly↗
PubMed1984

Human leukemic K562 cells: differential effects of 5-azacytidine on DNA methylation of epsilon-, gamma-globin and 7SL RNA genes.

5 Azacytidine ribonucleoside (5 Aza CR), greatly enhances erythroid differentiation of the K562(h) cell line, with a sharp increase of embryonic and fetal globin gene expression. This phenomenon is correlated with the undermethylation of gamma-globin but not of epsilon-globin, as the epsilon-globin gene is already extensively undermethylated before 5AzaCR induction. By contrast no variations in both DNA methylation and expression are observed in 7SL RNA genes.

Azacitidine↗
PubMed1982

[Echocardiographic diagnosis of aneurysm of Valsalva's sinus with fistulization into the right atrium].

The preoperative diagnosis of an aneurysm of the posterior sinus of Valsalva with rupture into the right atrium was made by echocardiography in a 21-year-old patient. The M-mode echocardiography revealed the following findings: 1) a vibrating anomalous structure, continuous with the aortic wall, was present in the right atrium. The echo-producing mass was the wall of the aneurysm, which adhered to the septal leaflet of the tricuspid valve during early-to-mid systole and had an abrupt posterior motion in late systole. In diastole, the wall of the aneurysm descended into the tricuspid orifice and its motion was similar to that of the septal leaflet of the tricuspid valve; 2) an echocardiographic sweep from the aorta to the left ventricle showed that the posterior wall of the aorta "crossed" the mitral orifice; 3) the pulmonic and tricuspid valves were normal. The 2-D echocardiographic findings gave support to the M-mode diagnosis: 1) in the short-axis view (at the level of the aorta) two lines of echoes came off the right side of the aortic wall and invaded the right atrium. These echoes were produced by the walls of the aneurysm; 2) in the apical four-chamber view the aneurysm descended into the tricuspid orifice in diastole, whereas it was lifted by the septal leaflet of the tricuspid valve in systole. The aneurysm appeared as vibrating lump on the closed tricuspid valve. Recognition of these features provides a potential non-invasive way to diagnose this anomaly. To our knowledge this is the first description of the characteristic echocardiografic picture of an aneurysm of the sinus of Valsalva with rupture into the right atrium.

Adult↗
PubMed1981

[Aneurysm of the membranous septum associated with interventricular patency. Echocardiographic study].

It has been documented by others that spontaneous closure or diminution in size of membranous ventricular septal defect is often associated with aneurysmal formation of the membranous septum. In a series of 51 patients, who underwent cardiac catheterization and cineangiocardiography for evaluation of the severity of a ventricular septal defect, 7 patients showed an aneurysm of the membranous interventricular septum (VSA) associated with a small ventricular septal defect (VSD). M-mode echocardiography was useful in the detection of VSA in 6 of them. Echocardiographic findings were not uniform in all cases. In most instances they consisted of linear echoes, that seemed to come off from the base of the interventricular septum and to protrude within the right ventricle in systole; the echoes from the VSA showed a coarse fluttering. Even if errors can be minimized by a correct technique, anomalous echoes from the VSA might however be confused with those of other anatomical structures (aortic root, tricuspid valve, etc.). M-mode echocardiography seems to be useful for the followup of patients with membranous VSD. The detection of VSA by ultrasonic means should suggest a good prognosis for VSD, possibly avoiding the need for repeat invasive studies.

Adolescent↗
PubMed1980

[Effects of the intravenous infusion of althesin on intracranial pressure and related functions].

30-60 min after the i.m. administration of 0.5 mg atropine sulphate, 9 adult conscious neurosurgical patients on spontaneous ventilation were given a total of 12 i.v. infusions of Althesin at a rate of 0,25-0,60 ml/kg/h able to induce stable clinical and EEG levels of anaesthesia. PICm, PAm and PVCm respectively decreased in all, in ten and in six administrations. The PAm decreased below 60 mmHg in only one case, in another there was no change and in another still it increased in a stable manner. In all cases PICm, PAm and PVCm decreased by a mean of 3.88 +/- 1.22 (P < 0,05), 20,76 +/- 17,44 (P < 0,05) and 0,90 +/- 1,50 mmHg. The paCO2 generally increased and, in only one case, did it induce an intracranial hypertensive reaction; the paO2 was frequently reduced. The interruption in the infusion was followed by the regression of all effects. This appened for the PICm and PAm without dangerous rebound effects. The clinical use of Althesin in neurosurgical patients is discussed with regards to problems of anaesthesia and intensive care.

Adult↗
PubMed1980

[Changes in intraocular pressure in anesthesia induced with althesin and maintained with methoxyflurane].

Intraocular pressure and arterial blood pressure were studied in 27 patients undergoing anaesthesia induced by 0,6-1 mg/kg of Althesin iv and maintained by methoxyflurane-N2O-O2 on spontaneous ventilation. All patients were scheduled to undergo various types of eye surgery, including open-eye surgery. Patients with glaucoma and cataract were administered 20% mannitol two hours prior to surgery. In all cases premedication was based on meperidine, promethazine and atropine sulphate im. During the entire period of anaesthesia the intraocular pressure and, generally, arterial blood pressure appeared to be lowered.

Adolescent↗