Search PubMed⌕ Search

Biomedical subjects

E Riva

Publications and source records attributed to E Riva.

At least 163 records · Page 9Linked to original sources
PubMed1991

Reduced plasma C-20 and C-22 polyunsaturated fatty acids in children with phenylketonuria during dietary intervention.

The fatty acid composition of plasma and erythrocyte lipids was analyzed in 15 children with phenylketonuria (aged 3 to 12 years) during dietary treatment aimed to maintain plasma phenylalanine levels at less than 8 mg/dl (485 mumol/L), and compared with those of 12 matched control subjects. The diet of children with phenylketonuria provided less protein, with a very low proportion of animal proteins, less fat, but a higher proportion of linoleic acid as a percentage of calories, and a higher carbohydrate content versus that in the diet of control subjects. The children with phenylketonuria had higher plasma levels of oleic acid but lower levels of arachidonic (n-6) and n-3 fatty acids. Linoleic and eicosatrienoic (n-9) acid levels were the same in both groups. These changes in patients with phenylketonuria resemble those observed in vegetarians and may be due to the absence of preformed arachidonic acid and long-chain n-3 fatty acids in the phenylketonuric diet.

Child↗
PubMed1991

The alpha- and beta-adrenoceptor blocking activities of labetalol and its RR-SR (50:50) stereoisomers.

1. We compared the alpha 1-, alpha 2- and beta 1-adrenoceptor blocking potencies of labetalol with those of its two stereoisomers (RR and SR) in pithed rats and in homogenized rat cerebral cortex and heart. 2. In pithed rats, labetalol and the RR-SR combination were given orally either at doses of 25 and 50 mg kg-1 body wt. or intravenously at doses of 1 and 5 mg kg-1 body wt. Prazosin 4 and 20 micrograms kg-1 body wt. and propranolol 1 and 5 mg kg-1 body wt., were given intravenously for comparison studies of potency at alpha 1- and beta 1-adrenoceptors, respectively. Effects were studied before and after i.v. administration of either phenylephrine (at doses which increased the mean arterial pressure by approximately 80 mmHg) or isoprenaline (at doses that increased heart rate by approximately 100 beats min-1). 3. In pithed rats, labetalol and the RR-SR combination antagonized, in a dose-dependent manner, the pressor effect of phenylephrine (P less than 0.05) and the chronotropic effect of isoprenaline (P less than 0.05). Following both oral and intravenous dosing, the RR-SR combination was twice potent as labetalol in terms of alpha 1- and beta 1-adrenoceptor antagonism at equivalent doses. 4. Labetalol and the enantiomers lacked affinity at alpha 2-adrenoceptors while at alpha 1-adrenoceptors the order of potency was prazosin much greater than RR-SR greater than labetalol. At beta 1-adrenoceptors, the affinity of the compound RR-SR was about 3 times that of labetalol.5. As labetalol is a mixture of active (RR and SR) and inactive (SS and SR) enantiomers (in terms of alpha and beta receptor actions), the combination of RR and SR may be a valuable substitute for labetalol in the treatment of systemic hypertension. Although the potential for non-specific side effects (common to all four enantiomers) could be expected to be diminished, recent reports by postmarketing surveillance indicate that the RR isomer (dilevalol) can induce liver toxicity. Interestingly, labetalol is devoid of this effect; whether the combination of RR and SR enantiomers could be of clinical importance warrants further investigation.

Adrenergic alpha-Antagonists↗
PubMed1991

Calcium and cardioplegia in neonates: dose-response and time-response studies in rats.

Isolated Langendorff-perfused rat hearts (n = 6/group) were subjected to 60, 90, 120, or 180 min of ischemia with or without a 2-min preischemic infusion with St. Thomas' Hospital cardioplegic solution that had been modified to contain concentrations of calcium of 0, 0.5, 0.8, 1.0, 1.2, 1.8, or 2.4 mM. In general, irrespective of the calcium concentration, hearts in the cardioplegia group recovered better than those in the noncardioplegia group. There was no consistent relationship between calcium content and postischemic recovery of function or enzyme leakage after any of the durations of ischemia studied. However, as expected, there was a strong inverse relationship between recovery and duration of ischemia. The recovery of function correlated with enzyme leakage but not with the time to onset or magnitude of ischemic contracture. In conclusion, although the neonatal rat heart benefits from cardioplegia the protection is less impressive than that reported for adult hearts. Nonetheless, the neonatal heart appears to be very resistant to ischemia. We propose that many of these differences can be explained on the basis of differences in myocardial calcium handling between neonate and adult.

Animals↗
PubMed1990

Haplotype distribution and molecular defects at the phenylalanine hydroxylase locus in Italy.

In order to investigate the molecular basis of phenylketonuria (PKU) in Italy, we characterized the RFLP haplotypes at the phenylalanine hydroxylase gene in 38 unrelated Italian PKU families. The distribution of haplotypes associated with PKU alleles differs from that of other European populations. In particular, haplotypes 1 and 6 are present in 39.7% and 17.6% of the PKU chromosomes, whereas the frequencies of haplotypes 2 and 3 are 5.9% and 2.9%, respectively. The characterization of PKU mutations using the polymerase chain reaction and allele-specific oligonucleotides shows that 1 out of 2 haplotypes 3 carries the splicing mutation and that 2 out of 4 haplotypes 2 carry the missense mutation associated with these haplotypes in North European populations. Our results indicate that the two molecular defects most frequent in Northern Europe represent a minority of PKU mutations in Italy.

Gene Frequency↗
PubMed1990

[Not Available].

Explore the source record for details and available documents.

Biochemistry↗
PubMed1989

Interaction study of fenoldopam--digoxin in congestive heart failure.

The potential interaction between fenoldopam, a DA1 selective agonist, and digoxin has been studied in 10 patients with heart failure (NYHA Class II or III) on chronic digoxin treatment. Plasma levels and urinary recovery of the glycoside were monitored for 24 h before and after 9 days of treatment with fenoldopam 100 mg tid. Fenoldopam caused a small, non-significant decrease in the mean steady state plasma concentration and area under the plasma concentration curve of digoxin. As the clearance of digoxin was unchanged there does not appear to be an interaction between fenoldopam and digoxin at the level of the renal tubule.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1989

Pharmacokinetics of cefonicid in children.

The pharmacokinetics of cefonicid was studied in 17 children requiring antibiotic treatment for respiratory or urinary tract infections. After informed consent had been obtained from the parents, a single dose of cefonicid 50 mg/kg/body weight was given by intramuscular injection. The mean peak serum concentration of 212.63 micrograms/ml was reached at 1.00 h, as absorption occurred at a very fast rate with a mean constant of 3.24 h-1. Mean values for half-life, apparent volume of distribution (Vz), total body clearance (CL), and renal clearance (CLR) were 3.24 h, 0.21 l.kg-1, 16.67 ml.min-1 and 13.60 ml.min-1 respectively. There was an inverse relationship between age and Vz, whereas CL and CLR were positively correlated with age. Cefonicid concentrations in urine were many times higher than the MICs of susceptible strains of bacteria. The study demonstrated that i.m. cefonicid 50 mg.kg-1 gave serum concentrations well within the therapeutic range for susceptible bacteria, and that its pharmacokinetic properties allow single daily doses to be used to treat infections in children.

Absorption↗
PubMed1989

Ibopamine as a substitute for digitalis in patients with congestive heart failure on chronic digoxin therapy. Smith Kline and French Ibopamine Group.

The substitution of digoxin with ibopamine, a new inotropic and vasodilating agent, was evaluated in a multicenter study in 58 patients with mild-to-moderate congestive heart failure, stabilized on diuretics, and digoxin therapy. The study was a parallel, double-blind, randomized trial of four weeks duration in which half of the group continued the pre-study medication (diuretics and digoxin) and half of the group was treated with diuretics and ibopamine (100 mg, three times a day). At baseline evaluation, the two groups were similar for age, sex, underlying cardiac disease, duration of congestive heart failure, symptom score, cardiothoracic ratio, echocardiographic parameters of left ventricular function and exercise tolerance as measured by bicycle ergometry. After four weeks, no clinical deterioration was found in the patients treated with ibopamine in any measured parameter. There were two deaths during the study: a sudden death and one following an acute myocardial infarction. Both patients were on digoxin. This study suggests that in patients with mild-to-moderate congestive heart failure, ibopamine therapy may effectively and safely substitute digoxin therapy for up to four weeks, representing an option for patients requiring inotropic support but are at risk for potential digoxin toxicity.

Adult↗
PubMed1989

Anti-arrhythmic effects of amiodarone and desethylamiodarone on malignant ventricular arrhythmias arising as a consequence of ischaemia and reperfusion in the anaesthetised rat.

The effects of amiodarone and its metabolite desethylamiodarone on arrhythmias induced by ischaemia and reperfusion were studied in vivo in the anaesthetised rat with transient regional ischaemia (7 min of left coronary artery occlusion) and reperfusion (10 min). Amiodarone or desethylamiodarone were administered intravenously either 10 min prior to ischaemia or 2 min prior to reperfusion. Control rats received an equivalent volume of vehicle. Administration of 5.0 mg.kg-1 amiodarone or desethylamiodarone prior to ischaemia reduced the incidence of ventricular tachycardia during the ischaemic period from 67% to 20% (p less than 0.02) and 47% respectively. During reperfusion, mortality was reduced from 53% to 7% and 7% (p less than 0.02) respectively, and reperfusion induced ventricular fibrillation from 73% to 20% (p less than 0.01) and 47% respectively. When the drugs were given prior to ischaemia, the plasma concentrations of amiodarone and desethylamiodarone were 1.03 (SEM 0.18) and 0.22(0.02) micrograms.ml-1 and the myocardial concentrations were 23.43(2.78) and 30.41(1.87) micrograms.g-1 respectively. Similar concentrations were found in plasma and myocardium with drugs given prior to reperfusion. No significant differences in plasma or myocardial concentrations of amiodarone or desethylamiodarone were observed between animals which developed ventricular fibrillation and those which did not. In conclusion, this study demonstrates that desethylamiodarone can, like its parent compound, protect the heart against malignant ventricular arrhythmias arising as a consequence of regional myocardial ischaemia and reperfusion.

Amiodarone↗
PubMed1989

A42867, a novel glycopeptide antibiotic.

A42867 is a new glycopeptide antibiotic of the ristocetin-vancomycin class active against aerobic and anaerobic Gram-positive bacteria. A42867 is produced by a strain of Nocardia nov. sp. ATCC 53492. A42867 was isolated during a screening program aimed at the discovery of new members of this glycopeptide class of antibiotics, by affinity chromatography based on an acyl-D-alanyl-D-alanine probe. The structure of A42867 was elucidated by fast atom bombardment MS, high field 2D 1H NMR spectroscopy, and HPLC analysis of the hydrolyzed carbohydrates. A42867 differs from vancomycin in the sugar portion and in the presence of only one chlorine atom in the peptide core. Its biological activity on Gram-positive aerobic and anaerobic bacteria is similar to that of other antibiotics of this group.

Aminoglycosides↗
PubMed1989

Ibopamine: long-term safety study in patients with congestive heart failure. The Italian Ibopamine Working Group.

Ibopamine is a new orally active dopamine analogue with positive inotropic and vasodilating activity. The tolerability of the drug administered at the dose of 100 mg thrice daily for 12 months was studied in 302 patients with congestive heart failure, New York Heart Association (NYHA) class II and III. Of the 302 patients, 198 completed the study (65%); 59 patients (19%) were withdrawn for clinical events; 27 of them died (9%); 35 patients (12%) did not complete the study for non-compliance and 10 (3%) for protocol violations. Clinical events were generally related to the cardiovascular system and 85% of deaths were from cardiovascular causes. None of the deaths was considered related to treatment by the investigators. Clinically significant laboratory abnormalities were observed during the study in four patients only. This trial suggests that ibopamine is well tolerated in patients with congestive heart failure, NYHA class II and III, at the dose of 100 mg thrice daily for up to one year.

Adolescent↗
PubMed1988

Pharmacokinetics and pharmacodynamics of propafenone during acute and chronic administration.

The pharmacokinetics of propafenone and 5-OH-propafenone and their relationship with the antiarrhythmic action and side effects have been studied in 10 patients with stable, frequent, premature ventricular beats (224-928 premature ventricular complexes/h). Observations were made after a single dose of propafenone 300 mg p.o., and after 1 and 3 months (only 5 out of 10 patients) of therapy with 300 mg t.d.s. After 1 month of treatment the plasma elimination half-life of propafenone (6.7 h) was almost twice as long as after a single dose (3.5 h), and the area under the plasma propafenone concentration-time curve (7620 ng.ml-1.h) was significantly larger than after single dose (3522 ng.ml-1.h); this was also true for the metabolite. The ratio of the AUCs of 5-OH-propafenone and propafenone decreased from the single dose (0.63) to 1 month (0.32). These variables remained stable up to 3 months. Eight patients had greater than or equal to 75% reduction of premature ventricular complexes after 3 days of therapy, and in 7 they were completely suppressed; the response was maintained over 1 to 3 months. Side effects were minor and in no case had the drug to be withdrawn or the dose reduced. Thus, the kinetics of propafenone were time-dependent. Its active metabolite did not accumulate greatly during chronic treatment. The lasting antiarrhythmic effect observed in some patients suggests a b.d.s. regimen instead of t.d.s. dosing in selected patients.

Adult↗
PubMed1988

Serotonin and noradrenaline concentrations and serotonin uptake in platelets from hyperphenylalaninaemic patients.

In three untreated patients with phenylketonuria (PKU), three PKU and six hyperphenylalaninaemic (HPA) patients in good metabolic control, the kinetic constants of platelet in vitro uptake of [14C]serotonin (5HT) did not significantly differ from those in 12 control subjects matched for age. The platelet concentrations of endogenous 5HT and noradrenaline (NA), taken as long-term indices of the amount of these amines circulating in plasma, were lower than normal in PKU and HPA patients, whether or not they were kept on a diet. However, a reduction in plasma NA concentrations at the moment of blood collection was seen only in untreated PKU patients. These data indicate that there may be a chronic inhibition of 5HT and possibly of NA synthesis even in PKU or HPA subjects in good metabolic control, with normal psychomotor development and only slightly raised plasma phenylalanine levels.

Adolescent↗
PubMed1988

Pattern reversal visual evoked potentials in phenylketonuria.

The pathogenesis of brain dysfunction in phenylketonuria (PKU) is still under investigation. Hyperphenylalaninaemia results in increased turnover of myelin. In order to demonstrate the derangement of myelinization in PKU we studied the visual evoked potentials (VEP) in 14 PKU patients and in 20 normal subjects. VEP findings were correlated with the metabolic control of the disease and with the electroencephalographic findings. VEP were more sensitive than the EEG in detecting a neurological dysfunction. VEP are influenced by dietary control and are normal only in children with good metabolic control.

Adolescent↗