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Biomedical subjects

M Brassard

Publications and source records attributed to M Brassard.

11 recordsLinked to original sources
PubMed2003

Management of fetal tachyarrhythmia based on superior vena cava/aorta Doppler flow recordings.

OBJECTIVE: To evaluate a management protocol of fetal supraventricular tachycardia (SVT) based on prior identification of the underlying mechanism. DESIGN AND SETTING: Prospective study in a mother-child tertiary university centre. PATIENTS: During a consecutive 36 month period, 18 fetuses with sustained SVT underwent a superior vena cava/ascending aorta (SVC/AA) Doppler investigation in an attempt to determine the atrioventricular (AV) relation and to treat the arrhythmia according to a pre-established management protocol. MAIN OUTCOME MEASURE: Rate of conversion to sinus rhythm. RESULTS: Seven fetuses had short ventriculoatrial tachycardia, five of these with a 1:1 AV conduction suggesting re-entrant tachycardia. The first choice drug was digoxin and all were converted. One fetus had AV dissociation leading to the diagnosis of junctional ectopic tachycardia, which was resistant to digoxin and sotalol; amiodarone achieved postnatal conversion. One fetus had SVT and first or second AV block; the diagnosis was atrial ectopic tachycardia (AET), which responded to sotalol given as a drug of first choice. Seven fetuses had long ventriculoatrial tachycardia: one with sinus tachycardia (no treatment), one with permanent junctional reciprocating tachycardia (PJRT), and three with AET. The first choice drug was sotalol and all were converted. One AET was classified postnatally as PJRT. Six fetuses had intra-atrial re-entrant tachycardia: five with 2:1 AV conduction and one with variable block. The first choice drug was digoxin. Conversion was achieved in all but one, who died after birth from advanced cardiomyopathy. CONCLUSION: The electrophysiological mechanisms of fetal SVT can be clarified with SVC/AA Doppler. The proposed management protocol has so far yielded a good rate of conversion to sinus rhythm.

Anti-Arrhythmia Agents↗
PubMed2002

Comparable efficacy and safety profiles of once-per-cycle pegfilgrastim and daily injection filgrastim in chemotherapy-induced neutropenia: a multicenter dose-finding study in women with breast cancer.

BACKGROUND: Neutropenia is common in patients receiving myelotoxic chemotherapy. Pegfilgrastim, a sustained-duration filgrastim is a once-per-cycle therapy for prophylactic neutrophil support. PATIENTS AND METHODS: Women, treated with four cycles of doxorubicin/docetaxel chemotherapy every 21 days, received pegfilgrastim or filgrastim 24 h after chemotherapy as a single subcutaneous injection per chemotherapy cycle (pegfilgrastim 30, 60 or 100 microg/kg) or daily subcutaneous injections (filgrastim 5 microg/kg/day). Safety, efficacy and pharmacokinetics were analyzed. RESULTS: The incidence of grade 4 neutropenia in cycle 1 was 95, 90 and 74%, in patients who received pegfilgrastim 30, 60 and 100 microg/kg, respectively, and 76% in patients who received filgrastim. Mean duration of grade 4 neutropenia in cycle 1 was 2.7,2 and 1.3 days for doses of pegfilgrastim, and 1.6 days for filgrastim. The pharmacokinetics of pegfilgrastim were non-linear and dependent on both dose and neutrophil count. Pegfilgrastim serum concentration was sustained until the neutrophil nadir occurred then declined rapidly as neutrophils started to recover, consistent with a self-regulating neutrophil-mediated clearance mechanism. The safety profiles of pegfilgrastim and filgrastim were similar. CONCLUSIONS: A single subcutaneous injection of pegfilgrastim 100 microg/kg provided neutrophil support and a safety profile comparable to daily subcutaneous injections of filgrastim during multiple chemotherapy cycles.

Adult↗
PubMed1999

Outcome of children with atrial septal defect considered too small for surgical closure.

There are few studies providing information on the natural course of hemodynamically insignificant atrial septal defect (ASD). To review the outcome of patients with secundum ASD, we retrospectively reviewed the charts of patients who had initially not been considered for surgical closure after age 1 year, and who had either a follow-up of at least 10 years or documented closure. Thirty patients, 22 females and 8 males, fulfilled our inclusion criteria. Mean age at diagnosis was 1.3 year and mean follow-up duration was 11.5 years. Seventeen patients had spontaneous closure of the ASD at a mean age of 8.4 years. There were 7 asymptomatic patients whose ASD was still patent at the last visit (mean age 14.1 years, mean follow-up 13.2), with defect dimensions on echocardiography ranging from 1 to 6 mm. The remaining 6 patients were considered to require surgical closure on the basis of an apparent increase in size of the ASD and secondary clinical and hemodynamic manifestations. These results (1) confirm that not all secundum ASDs need to be treated surgically because they can still spontaneously close past the age of 5, and (2) suggest that in a minority of cases the size of the defect could increase.

Cardiac Surgical Procedures↗
PubMed1999

Prognostic markers in twin pregnancies with an acardiac fetus.

OBJECTIVE: With twin reversed arterial perfusion sequence, the normal cotwin is at risk of heart failure. The purpose of this study was to identify ultrasonographic variables that can help predict prognosis. We hypothesized that variables reflecting the hyperdynamic circulatory condition of the normal fetus and the changes in circulatory impedance in the acardiac mass would correlate with final outcome. METHODS: Ten twin pregnancies with this condition were identified. Follow-up was available for nine. Adverse outcome was defined as death, cardiac failure, or delivery before 30 weeks' gestation for reasons related to the presence of the mass. The following data were collected on the normal fetus: cardiothoracic ratio and left ventricular shortening fraction; and on the mass: maximal length, presence and size of cysts, and presence of a rudimentary heart. The pulsatility index (PI) of the umbilical arteries (UA) of both twins was measured. RESULTS: Four fetuses died, two in utero (22 weeks) and two after cesarean (26 and 31 weeks) for advanced cardiac failure. In the five other cases, the outcome was favorable. The cardiothoracic ratio and presence of cysts or of a rudimentary heart did not correlate with outcome. A PI in the mass' UA significantly lower than that of the normal twin (ratio of 0.71 compared with 1.04 for good outcome, P<.05), an elevated shortening fraction in the second trimester, and a rapid growth rate of the mass were associated with a poor prognosis. CONCLUSION: In pregnancies with twin reversed arterial perfusion sequence, final outcome and treatment decisions can be determined based on hemodynamic criteria.

Adult↗
PubMed1989

Evidence that increases in circulating catecholamines of adrenal origin are not involved in pressor response to bilateral carotid occlusion in anaesthetized dogs.

1. We studied whether or not circulating catecholamines of adrenal origin play a major role in cardiovascular responses evoked by bilateral carotid artery occlusion (3 min) in anaesthetized dogs. 2. In the control group, the following parameters increased significantly (P less than 0.05) during bilateral carotid occlusion: aortic systolic pressure, heart rate, net adrenal catecholamine output, net renal noradrenaline output, and plasma catecholamine concentrations in aortic blood. Similar responses were obtained during the second occlusion performed approximately 25 min after the first occlusion. 3. After functional adrenalectomy (ADRX: diversion of adrenal venous blood flow), the increase in aortic adrenaline concentration observed during bilateral carotid occlusion was abolished. The increase in aortic noradrenaline concentration during the occlusion was significantly attenuated by approximately 60% (P less than 0.01) after ADRX. 4. The increase in net renal noradrenaline output during bilateral carotid occlusion after ADRX was not different from that observed before ADRX. Similarly, the response of aortic systolic pressure and heart rate during the occlusion was unaffected by ADRX. Furthermore, the increase in net adrenal catecholamine output during the occlusion was not affected by ADRX itself. 5. From these results, we conclude that the increase in circulating catecholamines of adrenal origin during bilateral carotid occlusion is not a major determinant for the increases in aortic pressure and heart rate. The results suggest that these cardiovascular responses during the occlusion are mediated principally by neuronal noradrenaline released from peripheral sympathetic nerve terminals.

Adrenal Glands↗
PubMed1989

Direct evidence that an increase in aortic norepinephrine level in response to insulin-induced hypoglycemia is due to increased adrenal norepinephrine output.

This study reports on the major source of circulating norepinephrine that is known to increase, progressively, during sustained hypoglycemia induced by intravenous insulin administration. Plasma concentrations of epinephrine, norepinephrine, and dopamine were simultaneously determined for adrenal venous and aortic blood in dogs anesthetized with sodium pentobarbital. The model used allowed us to perform a functional adrenalectomy (ADRX), while continuously monitoring the adrenal medullary secretory function. Under basal conditions, the net output (micrograms/min) of adrenal epinephrine, norepinephrine, and dopamine were 0.169 +/- 0.074, 0.067 +/- 0.023, and 0.011 +/- 0.003, respectively. Plasma concentrations (ng/mL) of aortic epinephrine, norepinephrine, and dopamine were 0.132 +/- 0.047, 0.268 +/- 0.034, and 0.034 +/- 0.009. Following insulin injection (0.15 IU/kg, i.v.), the net output (micrograms/min) of adrenal epinephrine, norepinephrine, and dopamine increased gradually (p less than 0.05), reaching the values of 0.918 +/- 0.200, 0.365 +/- 0.058, and 0.034 +/- 0.007 30 min after insulin administration. Similarly, aortic epinephrine, norepinephrine, and dopamine concentrations (ng/mL) increased significantly (p less than 0.05) to 0.702 +/- 0.144, 0.526 +/- 0.093, and 0.066 +/- 0.024. The aortic glucose concentration (mg/dL) was diminished from 81.8 +/- 4.1 to 36.9 +/- 3.4 (p less than 0.01). After taking the blood sample at 30 min following insulin administration, ADRX was immediately performed. Five minutes after the onset of ADRX, the net output (micrograms/min) of adrenal epinephrine, norepinephrine, and dopamine increased further to 1.707 +/- 0.374 (p less than 0.05), 0.668 +/- 0.139 (p less than 0.05), and 0.052 +/- 0.017.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1988

Intracellular pH change does not appear as a prerequisite for triggering activation of Barnea candida (Mollusca, Pelecypoda) oocytes.

Barnea candida oocytes, exposed to excess KCl, ammonia, or digitonin, exhibit germinal vesicle breakdown (GVBD) and reinitiate meiosis, at least up to first polar body extrusion. While we confirm that KCl- but not ammonia-induced activation required external calcium, our findings that digitonin is effective at any pH from 6 to 8, in the presence of calcium, while the phorbol ester TPA and diacylglycerol fail to reinitiate meiosis, strongly suggests calcium as the main trigger for this process. Preliminary experiments using the fluorescent probes fluorescein diacetate and Quin 2/AM show, moreover, that KCl and ammonia produce both an intracellular calcium surge (30 nM) and a slight alkalinization of the intracellular cytoplasm from 7.84 to 8.05.

Animals↗
PubMed1988

Contribution of adrenal norepinephrine output to increase aortic norepinephrine during carotid sinus reflex activation in anesthetized dogs.

Changes in circulating plasma catecholamine (CA: E, epinephrine; NE, norepinephrine; and DA, dopamine) concentrations in aortic (AO) blood were investigated in relation to variable rates of CA secretion from both adrenal (ADR) glands in response to bilateral carotid artery occlusion (BLCO) in vagotomized dogs anesthetized with sodium pentobarbital. During BLCO (3 min), AO systolic pressure (AP) increased along with significant increases in ADR-CA output, renal venous (RV) CA output, as well as in AO-E and NE concentrations. A ratio of NE:E in ADR venous and AO blood did not exceed 0.42 +/- 0.09 and 1.09 +/- 0.24 upon BLCO, respectively. In contrast, the NE:E ratio in RV blood increased significantly from 5.39 +/- 0.91 to 9.78 +/- 1.31. Following adrenalectomy (ADRX), the increase in AO-NE in response to BLCO was significantly attenuated by approximately 56%, but the increase in RV-NE output was not affected by ADRX. The results show that in vagotomized dogs, NE is co-released with E from the adrenal glands upon BLCO. The data also indicate that the increase in AO-NE concentration was dependent to a similar extent on the simultaneous increases in ADR-NE output and neuronal NE release. We conclude that under conditions where the sympathoadrenal system is activated, circulating plasma NE concentration may be significantly affected by an increase in ADR-NE output. Sympathetic neuronal contributions would, thereby, be overestimated in assessing overall sympathetic nerve activity by measuring circulating NE. NE concentrations in local venous effluent from individual organs may be more reliable estimates of the sympathetic nerve activity.

Adrenal Glands↗
PubMed1988

A differential effect of yohimbine on adrenal and neuronal catecholamine release during bilateral carotid occlusion in the dog.

This study reports on the effects of yohimbine and clonidine on the release of adrenal and renal catecholamines (epinephrine, E; norepinephrine, NE; and dopamine, DA) in response to bilateral carotid occlusion (BCO, 3 min) in vagotomized dogs anesthetized with sodium pentobarbital. The model used allowed us to simultaneously compare adrenal catecholamine secretion with neuronal NE release in the kidney. In control dogs, the net output (ng/min/g tissue) of adrenal E (70.5 +/- 19.7), NE (22.2 +/- 5.9) and DA (2.6 +/- 0.8) increased markedly (P less than 0.01) during BCO to a maximum level of 265.1 +/- 87.9, 97.4 +/- 30.6 and 10.5 +/- 3.2, respectively. Similarly, the net output (ng/min/g tissue) of renal NE (0.66 +/- 0.06) and DA (0.09 +/- 0.02) increased significantly (P less than 0.01) to 1.00 +/- 0.11 and 0.15 +/- 0.04, respectively. Aortic systolic pressure (mm Hg) (140.8 +/- 8.0) and heart rate (beats/min) (162.7 +/- 5.1) also increased (P less than 0.01) to 212.5 +/- 19.3 and 179.5 +/- 5.4, respectively. In dogs treated with yohimbine (0.3 mg/kg, i.v.), the net increase in adrenal catecholamine output was diminished by approximately 47% (P less than 0.05). In contrast, the net increase in renal NE output was potentiated by 41% (P less than 0.05). The net increase in heart rate was also enhanced significantly (P less than 0.01) in the presence of yohimbine. In dogs receiving clonidine (15 micrograms/kg, i.v.) the increases in net output of both adrenal and renal catecholamine were abolished. Similarly, pressor and heart rate responses were abolished in the presence of clonidine. The results indicate that yohimbine exerted a differential effect on renal sympathetic nerves (increase) and adrenal medullae (decrease) in modulating catecholamine release in response to BCO, while clonidine abolished both neural NE release and adrenal catecholamine secretion. This study suggests that a presynaptic alpha 2-adrenoceptor-mediated mechanism, the blockade of which enhances neural NE release at peripheral sympathetic nerve terminals in many tissues, may not be involved in the modulation of adrenal catecholamine secretion during BCO.

Adrenal Glands↗
PubMedDate not supplied

Treatment of unicameral bone cyst with demineralized bone matrix.

Eleven patients with active unicameral bone cysts were treated primarily with placement of demineralized bone matrix in the cyst by using a two-needle technique and a custom large-bore needle. Cyst healing was rated according to the Neer classification, and the average time of healing was 4.5 months. The demineralized bone matrix demonstrated an ability to obliterate the cyst in nine of 11 patients by using a single injection within 4-5 months, and at 2 years' follow-up, no cysts were deemed active or recurrent.

Bone Cysts↗