Biomedical subjects

J M Hascoet

Publications and source records attributed to J M Hascoet.

25 records · Page 2Linked to original sources

PubMed1992

Brain tissue heterotopia in the nasopharynx. Contribution of MRI to assessment of extension.

The authors report two cases of brain tissue heterotopia in the nasopharynx, without other malformations and, in one of the cases, with a persistent craniopharyngeal canal opening onto the heterotopia. This exceptional malformation is very similar to brain heterotopia in the nose, or "nasal glioma", which is more frequent and less diversified at histology. The malformation is revealed by obstruction of the pharynx with respiratory distress immediately after birth or during the first weeks of life. Total surgical excision provides cure without sequelae. The diagnosis is based on histology. MRI is essential to the diagnostic and pretherapeutic evaluation, notably to avoid missing an ectopic hypophysis, but it is insufficient to diagnose a sphenoidal meningoencephalocele.

Brain↗

PubMed1990

Effect of sympathetic nervous system on cerebral blood flow in the newborn piglet.

The role of the sympathetic nervous system on cerebral blood flow (CBF) autoregulation was evaluated in newborn piglets. Six animals were studied after ablation of the right superior sympathetic ganglion and compared to 6 control animals. Mean arterial blood pressure (MABP) was decreased by successive blood withdrawal and CBF was measured by radioactive microspheres. In denervated animals, MABP and CBF correlated positively according to a parabolic curve showing an absence of autoregulation when MABP is above 50 mm Hg (y = 0.079x2 - 5.9x + 154, p less than 0.01). In control animals, CBF remains stable throughout the experiment (y = 0.28x + 5). These data suggest a shift to the left of the upper limit of the autoregulation range in denervated animals and consequently a poor adaptation to increased MABP.

Animals↗

PubMed1989

Autoregulation of cerebral blood flow. Effect of phenobarbital and pancuronium in the newborn piglet.

The effect of phenobarbital and pancuronium on cerebral blood flow (CBF) and CBF autoregulation are studied in newborn piglets after chemically induced seizures with bicuculline. Given 3 or 15 min after the onset of seizures, phenobarbital significantly reduces CBF (59 +/- 11 and 56 +/- 17 vs. 84 +/- 24 ml/min/100 g - p less than 0.01). Moreover, during graded hypotension induced by graded haemorrhage, phenobarbital provides reestablishment of CBF autoregulation altered by seizures. In the same experimental model, pancuronium induces in control animals a rise of CBF (61 +/- 15 vs. 38 +/- 11 ml/min/100 g - p less than 0.001). During graded hypotension pancuronium is associated to a loss of CBF autoregulation (r = 0.76, p less than 0.001). Given as an adjunct treatment, in case of seizures, pancuronium has no significant effect on changes in cerebral haemodynamics. From these data, we conclude that pancuronium jeopardizes the haemodynamic adaptation to the induced hypovolemia and that phenobarbital may present a protective effect on cerebral haemodynamics and the subsequent risk for ischaemia or haemorrhage.

Animals↗

PubMed1987

Effects of tolazoline on regional blood flows in the newborn piglet.

To assess the effects of intravenous tolazoline on hemodynamics and regional blood flow distribution, 12 anesthetized newborn piglets were studied. Six piglets received saline and served as controls, the other 6 received two bolus doses of tolazoline (1 and 2 mg/kg). Mean arterial blood pressure decreased from control levels of 69.4 +/- 5.6 to 54.6 +/- 7.0 and 47.0 +/- 5.6 mm Hg, respectively, after 1 and 2 mg/kg of tolazoline, and heart rate increased from 220 +/- 9 to 270 +/- 13 and 282 +/- 8 beats/min, respectively. Cardiac output and regional blood flows were measured 15 min after tolazoline by the radioactive microsphere technique. Cardiac index did not change significantly. There was a redistribution of cardiac output toward the coronary circulation, with an increase in coronary blood flow from a control value of 249.3 +/- 39.9 to 361.0 +/- 56.4 ml/min/100 g of tissue after 1 mg/kg of tolazoline. Bronchial blood flow was also significantly increased. After a dose of 2 but not 1 mg/kg, the renal blood flow was markedly decreased from 139.8 +/- 17.8 to 104.4 +/- 24.5 ml/min/100 g. The other regional blood flows were not significantly modified. We conclude that tolazoline is a potent coronary vasodilator during the neonatal period. In addition we speculate that the decrease in renal blood flow might play a role in the renal toxicity of tolazoline.

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↗

PubMedDate not supplied

Prophylactic ibuprofen versus placebo in very premature infants: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Patent ductus arteriosus is a common complication of prematurity that frequently requires surgical or medical treatment. The benefit of prophylactic treatment by indometacin, a cyclo-oxygenase inhibitor, remains uncertain compared with curative treatment. This benefit could be improved with ibuprofen, another cyclo-oxygenase inhibitor with fewer adverse effects than indometacin on renal, mesenteric, and cerebral perfusion. We aimed to compare prophylactic and curative ibuprofen in the treatment of this abnormality in very premature infants. METHODS: We did a randomised controlled trial in infants younger than 28 weeks of gestation, who were randomly assigned to receive either three doses of ibuprofen or placebo within 6 h of birth. After day 3, symptomatic patent ductus arteriosus was treated first by open curative ibuprofen, then back-up indometacin, surgery, or both. The primary endpoint was need for surgical ligation. Analysis was per protocol. FINDINGS: The study was stopped prematurely after 135 enrollments because of three cases of severe pulmonary hypertension in the prophylactic group. 65 infants received prophylactic ibuprofen, and 66 received placebo. Prophylaxis reduced the need for surgical ligation from six (9%) to zero (p=0.03), and decreased the rate of severe intraventricular haemorrhage from 15 (23%) to seven (11%) (p=0.10). However, survival was not improved (47 [71%] placebo vs 47 [72%] treatment, p=1.00), because of high frequency of adverse respiratory, renal, and digestive events. INTERPRETATION: In premature infants, prophylactic ibuprofen reduces the need for surgical ligation of patent ductus arteriosus, but does not reduce mortality or morbidity. Therefore, it should not be preferred to early curative ibuprofen.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Persistence of impaired autoregulation of cerebral blood flow in the postictal period in piglets.

Cerebral blood flow (CBF) autoregulation was evaluated in the postictal period in unanesthetized term newborn piglets with a mean age of 5.7 +/- 3 days. Seven animals (group 1) received 1 mg/kg bicuculline to induce brief generalized seizures, and six control animals (group II) received saline. Twenty to 90 min after the end of seizure activity in group I or saline injection in group II, CBF was measured by the radioactive labeled microspheres method at three levels of mean arterial blood pressure (MABP) obtained by controlled blood withdrawal within the normal range for autoregulation. In the postictal period, baseline CBF was higher in group I than in group II (85 +/- 21 vs. 48 +/- 7 ml/min/100 g, p less than 0.001). During hypotension, total CBF was positively correlated with variations of MABP in group I (r = 0.739, p less than 0.01) but not in group II. Regional CBF showed the same correlation with MABP. These data show that after seizures in piglets, the rise in CBF is associated with a persistent impairment of CBF autoregulation. These hemodynamic alterations may be relevant in the pathogenesis of hemorrhagic or ischemic brain lesions.

Animals↗