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Biomedical subjects

P Vert

Publications and source records attributed to P Vert.

At least 73 records · Page 4Linked to original sources
PubMed1986

Effect of chronic exposure to methylxanthines on diazepam cerebral binding in female rats and their offsprings.

Caffeine, theophylline or saline were injected daily into female rats during the gestation and lactation periods. Crude synaptosomal membranes were isolated from the brains of offsprings at various stages of development and their ability to specifically bind [3H]diazepam was tested. An other approach consisted of injecting [3H]diazepam into offsprings and cerebral specifically bound diazepam was measured. It was shown that methylxanthines were able to inhibit [3H]diazepam binding by reducing total number of binding sites in the brain of 5- and 15-day-old rats born from treated mothers, with a total recovery of control values at 25 days of age. Moreover, in vivo percentage of cerebral bound diazepam dramatically fell when rats were exposed to methylxanthines in utero and through the mother's milk. Since caffeine and theophylline displace diazepam binding not necessarily in a competitive manner, it is suggested that they could interfere with diazepam as adenosine antagonists.

Animals↗
PubMed1986

Effect of diltiazem on hemodynamics and regional blood flows in the newborn piglet.

The aim of our study was to evaluate the effects of the calcium antagonist diltiazem (DTZ) on hemodynamics and regional blood flows measured with radioactive microspheres during the neonatal period. For this purpose, two bolus doses (0.5 and 1 mg/kg) of intravenous DTZ were injected in six 2- to 6-day-old urethan-anesthetized piglets. Six other piglets were injected with saline and served as controls. DTZ arterial plasma concentrations measured by high-pressure liquid chromatography were 0.521 +/- 0.034 and 1.141 +/- 0.073 microgram/ml, respectively, after 0.5 and 1 mg/kg. The only significant hemodynamic effects of DTZ were a decrease in mean arterial blood pressure and in heart rate. The main effect of DTZ on regional blood flow was a striking increase in coronary blood flow (by 54%) after both 0.5 and 1 mg/kg. To a lesser extent, DTZ increased significantly the blood flow to the brain, liver, ileum, diaphragm, and lungs. In contrast, DTZ at a dose of 1 mg/kg induced a significant decrease in renal blood flow (by 37%). We conclude that DTZ in the neonatal period is a nonspecific vasodilator. However, the decrease in renal blood flow induced by a dose of 1 mg/kg might be detrimental and requires further investigation.

Animals↗
PubMed1986

Plasma kinetics of parenteral tocopherol in premature infants.

The potential use of alpha-tocopherol (alpha-T) in the prevention of retrolental fibroplasia led to a study of the plasma kinetics of alpha-T. A dose of 20 mg alpha-tocopherol acetate (alpha-T-Ac) was injected subcutaneously in 5 premature newborns. alpha-T-Ac and alpha-T were assayed by high-pressure liquid chromatography. The maximum plasma concentration of alpha-T-Ac was 2.0 +/- 0.60 mg/dl (mean +/- SEM). alpha-T concentrations remained above 0.5 mg/dl from 8 to 168 h with a mean peak plasma concentration of 2.15 +/- 0.45 mg/dl. alpha-T-Ac absorption and elimination half-lives were 7.0 +/- 0.7 and 23.2 +/- 9.0 h, respectively; alpha-T appearance and elimination half-lives were 12.8 +/- 3.1 and 80.6 +/- 21.0 h. The proposed dosage to keep a plasma level higher than 0.5 mg/dl is 20 mg of alpha-T-Ac every 5 days.

Absorption↗
PubMed1986

[Gestational bone age of newborn infants].

A method for bone age calculation for neonates is reported. Criteria for maturation and growth are separately analysed. The chosen X ray charts were thorax including mandibula and profile of the right leg. 126 neonates 28 to 41 weeks of gestational age were studied. A linear regression is given. An area of confidence for growth and maturation for each gestational age has been designed. When gestational age is known, it gives the opportunity to appreciate the impact of a given pathology on these 2 data.

Age Determination by Skeleton↗
PubMed1985

Regional cerebral blood flow during bicuculline-induced seizures in the newborn piglet: effect of phenobarbital.

The changes in cerebral blood flow (CBF) during and after bicuculline-induced seizures were studied by the radioactive microsphere technique in 12 newborn, urethan-anesthetized piglets, 6 piglets pretreated with phenobarbital (10 mg/kg) and 6 without phenobarbital. The mean arterial blood pressure (MABP), PaO2, PaCO2 and the cerebral tissue pH (CtpH) were measured. CBF was increased during seizure, more in basal ganglia (98 and 106% in the control and phenobarbital group, respectively) than in brainstem, cerebellum and cortex. 15 min after seizure, CBF has returned to preseizure values. There was no significant difference at any time between the control and phenobarbital group. The increase in CBF was correlated with an increase in MABP (r = 0.753, p less than 0.01), suggesting a loss of cerebral autoregulation. CBF was significantly correlated with PaCO2 before and after seizure, but not during seizure. Finally, the increase in CBF was significantly correlated with an early increase in CtpH (r = 0.570, p less than 0.05), suggesting that brain acidosis is not involved in the pathogenesis of the increased CBF during seizures.

Acid-Base Equilibrium↗
PubMed1984

In vitro and in vivo displacement of [3H]-diazepam binding by purine derivatives in developing rat brain.

In vitro inhibiton of [3H]-diazepam binding to developing rat brain synaptosomal membranes has been studied. Adenosine, inosine, and hypoxanthine display approximately equal potencies as inhibitors of [3H]-diazepam binding to young rat brain membranes. In adult, inosine and hypoxanthine exhibit greater inhibitory potency. Data are also presented which show that the xanthine stimulants caffeine and theophylline competitively inhibit [3H]-diazepam binding with an equal potency throughout the development. In vivo study is also reported which shows that [3H]-diazepam binding to membranes from 5-day-old rats is displaced when female rats have been daily injected with caffeine or theophylline during gestation and lactation.

Animals↗
PubMed1983

Plasma and urinary kinetics of furosemide in newborn infants.

Plasma and urinary furosemide kinetics were assayed by high-power liquid chromatography in six newborn infants receiving furosemide (1 mg/kg body weight IV) for the treatment of fluid overload. Mean +/- SD for plasma half-life, apparent volume of distribution, and plasma clearance were, respectively, 9.5 +/- 4.4 hours, 173 +/- 28 ml/kg, and 15.3 +/- 8.4 ml/hr/kg. There was close correspondence between plasma and urinary half-lives and between plasma clearance and renal clearance. In the first 24 hours, mean estimated urinary recovery of unchanged furosemide was 90% of the injected dose (range 61% to 106%). The results suggest that in the newborn infant furosemide is virtually all excreted unchanged in the urine and that the absence of significant nonrenal elimination, together with the immaturity of neonatal renal function, accounts for its prolonged half-life in newborn infants.

Furosemide↗
PubMed1982

[Children of epileptic mothers (author's transl)].

A study of 115 children born to epileptic mothers treated during pregnancy showed a 6.9% increase in congenital malformation risk: 3 cleft lip-palate, 4 congenital cardiopathy and 1 arthrogryposis. The study also confirmed that these children were at risk of drug impregnation or withdrawal, dysmorphism with wide anterior fontanelle, and haemorrhage. The latter can be prevented by giving the mother vitamin K1 during the last weeks of pregnancy. The most characteristic finding was a high incidence (31%) of small head circumference at birth, frequently associated later with impaired somatic and psychomotor development during growth.

Abnormalities, Drug-Induced↗
PubMed1982

Pharmacokinetics of furosemide in neonates.

The pharmacokinetics of furosemide was evaluated in 12 newborns who received the drug transplacentally, and in 21 neonates who received it directly for therapeutic reasons. In the first group, the apparent plasma half-lives ranged from 96 to 6.8 h with a significant inverse relationship (p less than 0.01) between the gestational age and the elimination rate. In two cases a clear effect on diuresis was also observed. In the neonates receiving the drug i.v. for therapeutic reasons, the elimination kinetics appeared to follow a two-compartment open model, with a significant difference in the therminal plasma half-life between premature (26.8 +/- 12.2 h) and full-term newborns (13.4 +/- 8.6 h). In this group no relationship was observed between elimination rate and either gestational or conceptional age. In the case of repeated administration, an increase in plasma clearance and reduction in t1/2 beta was noticed.

Female↗
PubMed1982

Effect of a rocking bed on apnoea of prematurity.

We describe a rocking bed for use in incubators. Its effect was studied in 12 preterm infants with idiopathic apnoea, using each as his own control. All but one had less apnoea when the bed was rocking than when it was still. Apnoea associated with a significant fall in transcutaneous PO2 was less frequent, and fewer interventions were needed to terminate apnoeic attacks.

Apnea↗
PubMed1981

Study of the sensitivity of neonates to digoxin: contribution of erythrocyte 86rubidium uptake test.

In general, there is little agreement how digoxin should be used in newborn, and the results of studies in this field seem contradictory. This study attempts a quantitative assessment of the number and the sensitivity of cellular receptors for digoxin in the organism, by the in vitro measurement of erythrocyte 86Rubidium uptake in neonates compared with adults and old people. Red blood cells are first incubated with differing concentrations of digoxin, and then incubated with 86Rb. The initial level of 86Rb uptake (Rbi) is that observed in the absence of digoxin. The 50% index of captation (IC50) is the digoxin concentration in nanograms per ml at which 86Rb uptake is half Rbi. Three groups of patients were studied: Group I: 12 neonates, less than 5 days old; Group II: 11 adults (26 to 57 years old); Group III: 9 elderly people (71 to 82 years old). Rbi was significantly lower in neonates (Mean +/- SD: 25.8% +/- 3.5, P less than 0.001) and in the elderly (29.9% +/- 3.1) than in adults (36.8% +/- 4.6). IC50 was significantly lower in the elderly (12.1 ng/ml +/- 2.4) than in the adult patients (20.5 ng/ml +/- 5.5, P less than 0.001). In the newborns, values of IC50 were widely scattered (16.2 ng/ml +/- 7.2). The authors suggest that since Rbi reflects Na+, K+-ATPase activity, this activity is diminished in newborn and old people, and indicates that they have fewer cellular receptors for digoxin than adults. In the elderly, the low IC50 would imply increased sensitivity to digoxin. In neonates, the wide range of values for IC50 suggests considerable individual variation in sensitivity to digoxin. The results are consistent with the recently recommended lower dosages of digoxin in neonates.

Adult↗