Search PubMed⌕ Search

Biomedical subjects

S Riva

Publications and source records attributed to S Riva.

At least 91 records · Page 5Linked to original sources
PubMed1992

Assignment of the human heterogeneous nuclear ribonucleoprotein A1 gene (HNRPA1) to chromosome 12q13.1 by cDNA competitive in situ hybridization.

Heterogeneous nuclear ribonucleoprotein (HNRP) core protein A1 is a major component of mammalian HNRP particles. The human HNRP A1 protein was shown to be encoded by a 4.6-kb gene, split into 10 exons, belonging to a multigene family of about 30 A1-specific sequences per haploid genome, many of which correspond to pseudogenes of the processed type. Here we report the mapping of the human HNRPA1 gene to band 12q13.1. Localization was performed by nonisotopic in situ hybridization using a phage genomic clone that contains the active HNRPA1 gene as well as 13.5-kb flanking sequences. To suppress hybridization to pseudogene sequences, unlabeled HNRPA1 cDNA was added in excess over the probe to the hybridization mixture.

Binding, Competitive↗
PubMed1992

The gene for a novel human lamin maps at a highly transcribed locus of chromosome 19 which replicates at the onset of S-phase.

A previously described human DNA fragment which is replicated early in S-phase of HL-60 cell DNA (C. Tribioli, G. Biamonti, M. Giacca, M. Colonna, S. Riva, and A. Falaschi, Nucleic Acids Res. 15:10211-10232, 1987) was used to screen a genomic library in lambda Ch28. A clone which contained a 13.7-kb insert (L30E) found to code for several transcripts was isolated. The transcription of L30E DNA exhibited a complex pattern and a tissue-specific and proliferation-dependent type of regulation. The data were consistent with two tandemly arranged transcription units, the 3' end of one separated from the 5' end of the other by a sequence of about 600 bp containing an active promoter. The isolation and sequencing of L30E-specific cDNAs permitted identification of two genes, one of which encoded a B-type human lamin (analogous to mouse lamin B2). L30E DNA was mapped by in situ hybridization at the G-negative subtelomeric band p13.3 of chromosome 19. Interestingly, in synchronized HL-60 cells, L30E DNA is replicated in the first minute of S-phase. Replication of the lamin gene early in S-phase may reflect a coupling between early replication and transcription of genes for S-phase-specific proteins such as lamins.

Amino Acid Sequence↗
PubMed1991

Acute and chronic efficacy of felodipine in congestive heart failure.

In 13 patients with congestive heart failure we tested the acute hemodynamic effects of 5 vs. 10 mg felodipine tablets, in a double-blind, cross-over study. One hour after felodipine 5 mg, echocardiographic ejection fraction (%), cardiac index (thermodilution-ml/min/m2), and pulmonary wedge pressure (mm Hg) significantly changed (from 21 +/- 2 to 26 +/- 2, 2350 +/- 150 to 2790 +/- 160, 24 +/- 4 to 17 +/- 4) while they remained steady after felodipine 10 mg. The greatest stroke index increases were associated with felodipine 5 mg in 12 patients and 10 mg in 1 patient. Therefore we evaluated (open study) the long-term (2 months- 1 year) clinical and hemodynamic efficacy following the treatment with the acutely most effective dose (twice daily). After 2 months ejection fraction, cardiac index and pulmonary wedge pressure were respectively 24 +/- 2, 2550 +/- 150, and 18 +/- 4 (12 hours after the last drug administration, n = 11, P less than 0.02 from baseline). These parameters further increased one to two hours after the following administration of felodipine. Clinical improvement (reduction of 1 functional class, according to the New York Heart Association) was observed in 8/13 patients. These 8 patients participated to the one year follow-up. In 5 patients follow-up was interrupted because of acute cardiovascular events. However, before study interruption (5 patients) or ending (3 patients) clinical status did not worsen and ejection fraction remained higher than in the pretreatment period. Therefore, low dose felodipine might be used in the treatment of congestive heart failure.

Double-Blind Method↗
PubMed1990

Recombinant hnRNP protein A1 and its N-terminal domain show preferential affinity for oligodeoxynucleotides homologous to intron/exon acceptor sites.

The reported binding preference of human hnRNP protein A1 for the 3'-splice site of some introns (Swanson and Dreyfuss (1988) EMBO J. 7, 3519-3529; Mayrand and Pederson (1990) Nucleic Acids Res. 18, 3307-3318) was tested by assaying in vitro the binding of purified recombinant A1 protein (expressed in bacteria) to synthetic oligodeoxynucleotides (21-mers) of suitable sequence. In such a minimal system we find preferential binding of protein A1 to oligodeoxynucleotide sequences corresponding to the 3'-splice site of IVS1 of human beta-globin pre-mRNA and of IVS1 of Adenovirus type 2 major late transcript. Mutation studies demonstrate that the binding specificity is dependent on the known critical domains of this intron region, the AG splice site dinucleotide and polypyrimidine tract, and resides entirely in the short oligonucleotide sequence. Moreover specific binding does not require the presence of other hnRNP proteins or of snRNP particles. Studies with a truncated recombinant protein demonstrated that the minimal protein sequence determinants for A1 recognition of 3'-splice acceptor site reside entirely in the N-terminal 195 aa of the unmodified protein.

Base Sequence↗
PubMed1990

Alternative splicing in the human gene for the core protein A1 generates another hnRNP protein.

The human hnRNP core protein A1 (34 kd) is encoded by a 4.6 kb gene split into 10 exons. Here we show that the A1 gene can be differentially spliced by the addition of an extra exon. The new transcript encodes a minor protein of the hnRNP complex, here defined A1B protein, with a calculated mol. wt of 38 kd, that coincides with a protein previously designated as B2 by some authors. In vitro translation of the mRNAs selected by hybridization with A1 cDNA produced two proteins of 34 and 38 kd; Northern blot analysis of poly(A)+ RNA from HeLa cells revealed that the abundance of the A1B mRNA was approximately 5% that of A1. The A1B protein was detected by Western blotting with an anti-A1 monoclonal antibody both in enriched preparations of basic hnRNP proteins and in 40S hnRNP particles. The A1B protein exhibits a significantly higher affinity than A1 for ssDNA. The recombinant A1B protein, expressed in Escherichia coli, shows the same electrophoretic mobility and charge as the cellular one.

Amino Acid Sequence↗
PubMed1990

Coenzymatic properties of low molecular-weight and macromolecular N6-derivatives of NAD+ and NADP+ with dehydrogenases of interest for organic synthesis.

The catalytic activity, expressed as Km and Vmax values, of 16 enzymes of practical interest with the macromolecular coenzymes poly(ethylene glycol)-N6-(2-aminoethyl)-NAD+ and poly(ethylene glycol)-N6-(2-aminoethyl)-NADP+ and their low molecular weight precursors N6-(2-aminoethyl)-NAD+ and N6-(2-aminoethyl)-NADP+, was investigated. The enzymes examined are of direct interest for organic synthesis (i.e. alcohol dehydrogenase from yeast, horse liver, or Thermoanaerobium brockii, lactic dehydrogenase, and several hydroxysteroid dehydrogenases) or are used for the regeneration of NAD+, NADP+, NADH, or NADPH (i.e. glutamate dehydrogenase from liver or Proteus, formate dehydrogenase, glucose dehydrogenase, and malic enzyme). The cycling efficiency of poly(ethylene glycol)-N6-(2-aminoethyl)-NADP+ was examined with coupled-enzymes or coupled-substrates systems. Poly(ethylene glycol)-N6-(2-aminoethyl)-NAD+ and, even more so, poly(ethylene glycol)-N6-(2-aminoethyl)-NADP+ were excellent coenzymes with several dehydrogenases. In addition, the coenzymatic properties of N6-(3-sulfonatopropyl)-NAD+, an NAD+ derivative carrying a strong anionic group, were compared with those of the newly synthesized N6-(2-hydroxy-3-trimethylammonium propyl)-NAD+, an NAD+ derivative carrying a strong cationic group. It was expected that the presence of the sulfonic or quaternary ammonium group would enhance the residence time of the coenzyme inside continuous-flow reactors if membranes with anionic or cationic groups, respectively, were used.

Indicators and Reagents↗
PubMed1990

Hemodynamic and renin responses to nifedipine in renovascular hypertension.

We investigated the acute effects of nifedipine (10 mg orally) on renin and systemic hemodynamics in twelve patients who had severe hypertension (diastolic values averaging 114 mm Hg) with unilateral renal artery stenosis (angiography) and hyperreninemia. Plasma renin activity was determined from blood samples drawn from the aorta and from both renal veins, so that "ischemic lateralization" could be evaluated through appropriately derived indexes. Nifedipine promptly and significantly lowered aortic pressure in all patients. At 30 minutes maximal circulatory responses were recorded, which consisted of a 22% decrease in mean aortic pressure (from an average of 144.6 +/- 15 mm Hg to an average of 113 +/- 11 mm Hg), a 44% reduction of systemic vascular resistance (from 2162 +/- 540 dynes.sec.cm-5 to to 1205 +/- 279 dynes.sec.cm-5), a 33% rise in cardiac index (from 2920 +/- 970 ml/min/m2 to 3875 +/- 986 ml/min/m2). These effects were still evident, although somewhat tempered, after 180 minutes of continuous monitoring; they were qualitatively and quantitatively similar to those reported by some authors in persons with primary hypertension with similar levels of blood pressure. After nifedipine was given, renin activity of the systemic blood rose significantly, because of a potentiated release from the kidney with arterial stenosis. This effect, which was inferred as being due to further reduction of the renal perfusion pressure, improved the significance of "ischemic lateralization" indexes and supported the diagnosis of renovascular hypertension in all cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[The right ventricle and pulmonary circulation in hypertensive patients].

Elevated blood pressure and vascular resistance in patients with systemic hypertension are paralleled by a proportional rise in pressure and resistance in the lesser circulation. It was hypothesized that increased systemic reaction to adrenergic stimulation is shared by the pulmonary vessels. Thus normotensive subjects and patients with primary hypertension were investigated during mental arithmetic and the cold pressor test. Both groups responded to both stimuli; during arithmetic pressure reaction was mediated through an increase of cardiac output, and during the cold pressor test through a predominant rise in systemic vascular resistance. The pressure changes were emphasized in the hypertensive population. Pressure in the pulmonary artery in normotensive subjects was not affected by cold and was slightly raised (systolic) during arithmetic. In hypertensive patients, on the other hand, systolic and diastolic pressures were consistently augmented by both tests, and pulmonary arteriolar resistance rose by 42% and 29% of control during the cold pressor test and arithmetic, respectively. Changes in resistance reflected neurally-mediated vasoconstriction but not variations in the passive relationship between pressure and flow, since during arithmetic, for a similar rise in flow the driving pressure across the lungs was steady in normotensive subjects and rose significantly in hypertensive patients. In these same patients pressure was augmented by cold test in the absence of substantial changes in flow. At baseline and during tests pulmonary wedge pressure, pleural pressure, arterial blood gases, and pH were similar in the two populations. The intravenous infusion of similar scalar doses of norepinephrine (the same mediator released during cold test) was not effective on the pulmonary vessels of normotensives and caused an obvious vasoconstriction in hypertensives.(ABSTRACT TRUNCATED AT 250 WORDS)

Catecholamines↗
PubMed1990

[ST segment depression in precordial leads in patients with inferior acute myocardial infarction: the role of right ventricular involvement].

The aim of the present study was to evaluate the influence of right ventricular involvement on the magnitude of precordial ST segment depression during inferior acute myocardial infarction. For this reason 61 patients (55 M, 6 F; mean age 53 years--range 38-73 years) admitted in our CCU for inferior acute myocardial infarction were studied by coronary angiography within 3-5 days from the onset of symptoms. The angiography showed either occlusion or critical coronary stenosis ranging as follows: on right coronary artery proximal (Group 1) to the first branch for right ventricle in 22 patients, on right coronary artery distal to the first branch for right ventricle in 25 patients (Group 2) and on circumflex artery (Group 3) in 14 patients. No difference in LAD disease were noted between the 3 groups. Using myocardial scintigraphy (Tc-99m- pyrophosphate) we confirmed the presence or the absence of right ventricular involvement in the 3 groups. In the 3 groups the magnitude of ST segment depression in V2, selected as representative left-sided precordial lead, ranged as follows: Group 1: -0.25 +/- 1.34 mm; Group 2: -1.64 +/- 1.80 mm; Group 3: -2.00 +/- 1.97 mm. In patients with right ventricular involvement (Group 1) there was a statistically significant reduction of precordial ST segment depression either in comparison to Group 2 (p less than 0.01) or to Group 3 (p less than 0.005) but none between Group 3 and 2. (ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

A protein target site in an early replicated human DNA sequence: a highly conserved binding motif.

We have previously reported that a human nuclear factor, probably corresponding to the USF/MLTF protein [1,2], is able to bind specifically to a DNA sequence present in DNA replicated at the onset of S-phase [3]. Here we demonstrate that the same factor binds also to several other similar sequences, present in eukaryotic and viral genomes. Mutations or methylation in a CpG dinucleotide, central in the palindromic binding site, completely abolish binding. Furthermore, we present evidence for the existence of at least two other nuclear proteins in human cells with the same DNA binding specificity. The data presented suggest a strong evolutionary conservation, among distantly related organisms, of the binding motif, which is probably the target of a number of nuclear factors that share the same DNA binding specificity albeit in the context of different functions.

Base Composition↗
PubMed1989

Enzymatic synthesis of [4R-2H]NAD (P)H and [4S-2H]NAD(P)H and determination of the stereospecificity of 7 alpha- and 12 alpha hydroxysteroid dehydrogenase.

The stereospecifically labeled coenzymes [4R-2H]NADH, [4R-2H]NADPH and [4S-2H]NAD(P)H were synthesized enzymatically in high yield and high isotopic purity (greater than or equal to 95%) with 2HCOO2H/formate dehydrogenase, (CH3)2C2HOH/alchol dehydrogenase from Thermoanaerobium brockii and [1-2H]glucose/glucose dehydrogenase, respectively. This set of deuterated coenzymes was used to determine the stereospecificity of the previously unstudied 7 alpha-hydroxysteroid dehydrogenase from Escherichia coli (NAD-dependent) and 12 alpha-hydroxysteroid dehydrogenase from Clostridium group P (NADP-dependent). H-NMR and EI-MS of the nicotinamide moiety after enzymatic oxidation of deuterated NAD(P)H with dehydrocholic acid as substrate showed that both dehydrogenases are B-sterospecific.

Clostridium↗
PubMed1989

Isolation of an active gene encoding human hnRNP protein A1. Evidence for alternative splicing.

Heterogeneous nuclear ribonucleoprotein (hnRNP) core protein A1 is a major component of mammalian hnRNP 40 S particles. We describe the structure of an active A1 gene and report on the partial characterization of the A1 gene family. About 30 A1-specific sequences are present per haploid human genome: 15 such sequences were isolated from a human genomic DNA library. Many corresponded to pseudogenes of the processed type but by applying a selection for actively transcribed regions we isolated an active A1 gene. The gene spans a region of 4.6 x 10(3) base-pairs and it is split into ten exons that encode the 320 amino acid residues of the protein. The amino acid sequence derived from the exon sequences is identical with that deduced from cDNA and reported for the protein. One intron exactly separates the two structural domains that constitute the protein. Each of the two RNA-binding domains in protein A1 is encoded by one exon. Experimental evidence indicates that the A1 gene can encode for more than one protein by alternative splicing. The gene is preceded by a strong promoter that contains at least two CCAAT boxes and two possible Sp1 binding sites, but it lacks a TATA box.

Amino Acid Sequence↗
PubMed1989

Diagnosis of acute myocardial infarction by indium-111 antimyosin antibodies and correlation with the traditional techniques for the evaluation of extent and localization.

This clinical study evaluated the accuracy of planar myocardial scintigraphy with antimyosin monoclonal antibodies radiolabeled with indium-111 (AMA-Fab) in the detection and localization of acute myocardial infarction (AMI). Fifty-seven patients admitted for suspected AMI were studied; 17 patients underwent thrombolytic therapy with intravenous streptokinase and 11 had clinical signs of reperfusion; 9 had had a previous myocardial infarction. Fifty of 57 patients were discharged from the coronary care unit with a confirmed diagnosis of AMI. The AMA-Fab study results were positive for AMI in 49 patients (98%) and negative in 1 (2%). Among the 7 patients without AMI, 5 had unstable angina, 1 had Prinzmetal's variant angina and 1 had acute pancreatitis. AMA-Fab results were negative in 6 of 7 patients (85%) and positive in 1 (15%). Therefore, the sensitivity and specificity of AMA-Fab scintigraphy were 0.98 and 0.85, respectively. To assess accuracy in defining the extent and location of AMI, AMA-Fab results were compared with those of the electrocardiogram, echocardiogram, technetium-99m pyrophosphate myocardial scintigraphy and coronary angiography and left ventriculography. AMA-Fab scintigraphy showed a good concordance with the traditional techniques in the topographic definition of the infarcted regions. No uptake of AMA-Fab was seen in the regions of previous old infarcts. Ten healthy volunteers also underwent AMA-Fab scintigraphy. No evidence of myocardial tracer uptake was noted in them. No adverse reactions or side effects were noted after injection of AMA-Fab in any patient. It is concluded that planar myocardial scintigraphy with AMA-Fab is a reliable method for AMI detection and location.

Adult↗
PubMed1989

[Hemodynamic effects of the intravenous administration of captopril in patients with chronic congestive heart failure].

The aim of the present study was to evaluate the hemodynamic response to the intravenous administration of the angiotensin converting enzyme-inhibitor captopril. Plasmatic renin activity was also monitored. The study population included 10 patients with chronic congestive heart failure: 3 were in the second NYHA functional class, 5 in the third, and 2 in the fourth. The patients received a first dose of 5 mg of captopril followed, after 10 min, by a second bolus-dose of 15 mg. Hemodynamic and hormonal measurements were repeated in the following 4 hours. The greatest hemodynamic effect, considered as the time of maximal mean arterial pressure and systemic vascular resistances decrease, and cardiac index increase, was noted 20 min after the first bolus dose administration. Mean arterial pressure (MAP) decreased by 13% (p less than 0.01), mean pulmonary artery pressure (MPAP) by 14% (p less than 0.05), right atrial pressure (RAP) by 30% (NS), wedge pressure (WPP) by 23% (p less than 0.01), systemic vascular resistances (SVR) by 21% (p less than 0.05), pulmonary vascular resistances by 22% (NS); cardiac index (CI) increased by 12% (p less than 0.05), stroke volume index by 10% (NS). Heart rate didn't change. The plasmatic renin activity (PRA) increased by 339% (p less than 0.01) reaching the maximal level in concomitance with the greatest hemodynamic effect. Hemodynamic changes were already noted 5 min after the first dose and lasted up to 75 min later.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Circulatory and renin response to the administration of nifedipine in renovascular hypertension].

In 12 severe (diastolic values averaging 114 mmHg) hypertensives with unilateral renal artery stenosis (angiography) and hyperreninemia, we investigated the acute effects of nifedipine (10 mg orally) on renin and systemic hemodynamics. Plasma renin activity was determined on blood samples withdrawn from the aorta and both renal veins, so that "ischemic lateralization" could be evaluated through appropriated derived indexes. Nifedipine promptly and significantly lowered the aortic pressure in all patients. At 30 min maximal circulatory responses were recorded, which consisted of 22% decrease in mean aortic pressure (from an average of 144.6 +/- 15 to an average of 113 +/- 11 mm Hg), 44% reduction of systemic vascular resistance (from 2162 +/- 540 to 1205 +/- 279 dynes.S.cm-5), 33% rise of cardiac index (from 2920 +/- 970 to 3875 +/- 986 ml/min/m2). These effects were still evident, although somewhat tempered, after 180 min continuous monitoring; they were qualitatively and quantitatively similar to those reported by some authors in primary hypertensives with similar levels of blood pressure. After nifedipine, renin activity of the systemic blood significantly rose, due to a potentiated release from the kidney with arterial stenosis. This effect, that was interfered as a due to further reduction of the renal perfusion pressure, improved the significance of "ischemic lateralization" indexes and supported the diagnosis of renovascular hypertension in all of cases. It is suggested that nifedipine may not only be regarded as an additional diagnostic tool, but also as an effective antihypertensive agent in this disorder, al least in the short term. This contrasts with the previous suggestion of nifedipine as substantially more effective in low-renin rather than high-renin hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗