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Biomedical subjects

N Villeneuve

Publications and source records attributed to N Villeneuve.

At least 19 recordsLinked to original sources
PubMed2006

Use-dependent inhibition of hHCN4 by ivabradine and relationship with reduction in pacemaker activity.

BACKGROUND AND PURPOSE: Ivabradine, a specific and use-dependent I(f) inhibitor, exerts anti-ischaemic activity purely by reducing heart rate. The aim of this work was to characterize its effect on the predominant HCN channel isoform expressed in human sino-atrial nodes (hSAN), to determine its kinetics in HCN channels from multicellular preparations and rate-dependency of its action. EXPERIMENTAL APPROACH: RT-PCR analysis of the four HCN channel isoforms was carried out on RNAs from hSAN. Patch-clamp and intracellular recordings were obtained from CHO cells stably expressing hHCN4 and isolated SAN, respectively. Beating rate of rat isolated atria was followed using a transducer. KEY RESULTS: hHCN4 mRNAs were predominant in hSAN. Ivabradine induced a time-dependent inhibition of hHCN4 with an IC(50) of 0.5 microM. In rabbit SAN, ivabradine progressively reduced the frequency of action potentials: by 10% after 3 h at 0.1 microM, by 14% after 2 h at 0.3 microM and by 17% after 1.5 h at 1 microM. After 3h, ivabradine reduced the beating rate of rat right atria with an IC(30) of 0.2 microM. The onset of action of ivabradine was use-dependent rather than time-dependent with slower effects than caesium, an extracellular I (f) blocker. Ivabradine 3 microM decreased the frequency of action potentials in SAN from guinea-pig, rabbit and pig by 33%, 21% and 15% at 40 min, respectively. CONCLUSIONS AND IMPLICATIONS: The use-dependent inhibition of hHCN4 current by ivabradine probably contributes to its slow developing effect in isolated SAN and right atria and to its increased effectiveness in species with rapid SAN activity.

Action Potentials↗
PubMed2004

Gamma knife surgery for epilepsy related to hypothalamic hamartomas.

OBJECTIVE: Drug resistant epilepsy associated with hypothalamic hamartoma (HH) can be cured by microsurgical resection of the lesion. Morbidity and mortality risks of microsurgery in this area are significant. Gamma Knife Surgery's (GKS) reduced invasivity seems to be well adapted. In view of the severity of the disease and risks of surgical resection it is crucial to evaluate GKS for this indication. A first retrospective study has shown a very good safety and efficacy level but for a more reliable evaluation a prospective study would be required. METHODS: Between Oct 1999 and July 2002, 30 patients with HH and associated severe epilepsy were included. Seizure semiology (video EEG) and frequency, behavioural disturbances, neuropsychological performance, endocrinological status, sleep electroclinical abnormalities, MR imaging, and visual function were systematically evaluated before and after GKS (6, 12, 18, 24, 36 months). Twenty patients had experienced precocious puberty at a median age of 3,7 (0-9). Range of maximum diameter was from 7,5 to 23 mm with only 3 larger than 18 mm. The median marginal dose was 17 gy (14-20). RESULTS: Sufficient follow up for final evaluation is not yet available. Only 6 patients have a follow-up of more than 12 months and 19 more than 6 months. However a lot of very dramatic changes did occur during that period in this group. Among the 19 patients with more than 6 months of follow-up, a lot had already experienced an increase of gelastic seizures around 3 months (3), an improvement in their seizure rate (18), behaviour (9), sleep (3), and EEG background activity (3), a cessation of partial complex seizures (7). No complications have occurred till now except one patient experiencing at 5 months a hyperthermia without infection and concomitant increase of gelastic seizures both ceasing suddenly and spontaneously after 15 days. CONCLUSION: Our first results indicate that GKS is as effective as microsurgical resection and very much safer. GKS also allows to avoid the vascular risk related to radiofrequency lesioning or stimulation. The disadvantage of radiosurgery is its delayed action. Longer follow-up is mandatory for a serious evaluation of the role of GKS. Results are faster and more complete in patients with smaller lesions inside the 3rd ventricle (grade II). The early effect on subclinical discharges turns out to play a major role in the dramatic improvement of sleep quality, behaviour, developmental acceleration at school.

Adolescent↗
PubMed2004

[What organisation to improve health care management of patients with partial refractory epilepsy?].

Epilepsy is a common and serious neurological condition. It may have severe psychological, cognitive and social consequences. A good organisation of medical care is able to improve the quality of care offered to people with epilepsy. Only the Anglo-Saxon literature has attempted to analyse this problem. Two models of management has been described: epilepsy specialist nurse-based liaison service between primary and secondary/tertiary care and department specialized in epilepsy. These types of service are complementary but it is difficult to determine the best model the currently available results.

Anticonvulsants↗
PubMed2004

[Quality-of-life scales for patients with drug-resistant partial epilepsy].

Epilepsy is a chronic condition with numerous social and psychological consequences. Research on quality of life in epilepsy is characterized by different kind of methodology. Quality of life is worse in epileptic patients than in the general population. Quality of life is also comparable or worse in epileptic patients than in patients with other chronic conditions. But quality of life in well-controlled epileptic patients is similar to quality of life in healthy persons. Frequency of seizures seems to be one of the most relevant determinants of poor quality-of-life scores. Being seizure free is a necessary but not sufficient condition to have a good quality of life. Quality of life is worsened by the co-existence of depression. The impact of surgical treatment on quality of life is positive, in all ages, in correlation with seizure control. It is difficult to analyze the impact of drug therapy on quality of life. Because of the lack of a standardized approach summarizing the literature in the field remains extremely difficult.

Adult↗
PubMed2002

[Antiepileptics].

Antiepileptic drugs can be schematically classified according to their spectrum of action on generalized or partial epileptic seizures: sodium valproate, lamotrigine, benzodiazepines and topiramate are large spectrum molecules which are effective in generalized and partial epilepsies. Carbamazepine, vigabatrin, gabapentine, tiagabine, phenytoin and phenobarbital are effective in partial epilepsies. Ethosuccimide is effective in absence seizures. The main characteristics of these different drugs are described and the general principles of their prescription are recalled.

Anticonvulsants↗
PubMed2001

A broad spectrum of clinical presentations in congenital disorders of glycosylation I: a series of 26 cases.

INTRODUCTION: Congenital disorders of glycosylation (CDG), or carbohydrate deficient glycoprotein syndromes, form a new group of multisystem disorders characterised by defective glycoprotein biosynthesis, ascribed to various biochemical mechanisms. METHODS: We report the clinical, biological, and molecular analysis of 26 CDG I patients, including 20 CDG Ia, two CDG Ib, one CDG Ic, and three CDG Ix, detected by western blotting and isoelectric focusing of serum transferrin. RESULTS: Based on the clinical features, CDG Ia could be split into two subtypes: a neurological form with psychomotor retardation, strabismus, cerebellar hypoplasia, and retinitis pigmentosa (n=11), and a multivisceral form with neurological and extraneurological manifestations including liver, cardiac, renal, or gastrointestinal involvement (n=9). Interestingly, dysmorphic features, inverted nipples, cerebellar hypoplasia, and abnormal subcutaneous fat distribution were not consistently observed in CDG Ia. By contrast, the two CDG Ib patients had severe liver disease, enteropathy, and hyperinsulinaemic hypoglycaemia but no neurological involvement. Finally, the CDG Ic patient and one of the CDG Ix patients had psychomotor retardation and seizures. The other CDG Ix patients had severe proximal tubulopathy, bilateral cataract, and white matter abnormalities (one patient), or multiorgan failure and multiple birth defects (one patient). CONCLUSIONS: Owing to the remarkable clinical variability of CDG, this novel disease probably remains largely underdiagnosed. The successful treatment of CDG Ib patients with oral mannose emphasises the paramount importance of early diagnosis of PMI deficiency.

Adipose Tissue↗
PubMed2000

Hypercholesterolemia increases coronary endothelial dysfunction, lipid content, and accelerated atherosclerosis after heart transplantation.

Hyperlipidemia may increase endothelial damage and promote accelerated atherogenesis in graft coronary vasculopathy. To study the effects of hypercholesterolemia on coronary endothelial dysfunction, intimal hyperplasia, and lipid content, a porcine model of heterotopic heart transplantation, allowing nonacute rejection without immunosuppressive drugs, was used. A high cholesterol diet was fed to donor and recipient swine 1 month before and after transplantation. The endothelial function of coronary arteries of native and transplanted hearts from cholesterol-fed animals was studied in organ chambers 30 days after implantation and compared with endothelial function in arteries from animals fed a normal diet. The total serum cholesterol increased 3-fold in donors and recipients. Endothelium-dependent relaxations to serotonin, to the alpha(2)-adrenergic agonist UK14,304, and to the direct G-protein activator sodium fluoride were decreased significantly in allografted hearts compared with native hearts from both groups. Relaxations to the calcium ionophore A23187 and bradykinin were decreased significantly in allografts from animals fed the high cholesterol diet. The prevalence of intimal hyperplasia was significantly increased in coronary arteries from hypercholesterolemic swine. There was a significant increase in the lipid content of allograft arteries of hypercholesterolemic recipients. Hypercholesterolemia causes a general coronary endothelial dysfunction, increases the prevalence of intimal hyperplasia, and augments the incorporation of lipids in the vascular wall after heart transplantation. Hyperlipidemia accelerates graft coronary atherosclerosis through its effects on the endothelium.

Adrenergic alpha-Agonists↗
PubMed2000

Hot water epilepsy: a benign and unrecognized form.

Hot water epilepsy is a reflex epilepsy. Seizures are provoked by hot water, and result from the association of both cutaneous and heat stimuli. Described mainly in India and Japan, the condition seems to be rare in Europe, where it occurs in young children. We report five infants aged from 6 months to 2 years. They had brief seizures during bathing with activity arrest, hypotonia, and vasoactive modification; clonic movements were observed. A simple treatment-decreasing the bath temperature-can be sufficient. Sometimes an antiepileptic drug is required. Seizure course and psychomotor development are favorable. Hot water epilepsy is a benign form of epilepsy. Its incidence could be underestimated because of confusion with febrile convulsions, vagal fits, or aquagenic urticaria.

Electroencephalography↗
PubMed2000

Neonatal seizures induced persistent changes in intrinsic properties of CA1 rat hippocampal cells.

We investigated the effects of repeated early-life seizures induced by flurothyl inhalation on intrinsic membrane properties of hippocampal pyramidal neurons from young rats (postnatal day 15-20). Intracellular recordings of CA1 and CA3 pyramidal neurons from flurothyl-treated and control rats revealed no significant differences in resting membrane potential, input resistance, membrane time constant, and action potential characteristics. In CA1 pyramidal cells from flurothyl-treated rats, the spike frequency adaptation and afterhyperpolarizing potential following a spike train were markedly reduced when compared with controls. In contrast, no significant alterations in the firing properties of CA3 pyramidal neurons were found. It is concluded that neonatal seizures lead to persistent changes in intrinsic membrane properties of CA1 pyramidal neurons. These alterations are consistent with an increase in neuronal excitability and may contribute to the behavioral deficit and epileptogenic predisposition observed in rats that experienced repeated neonatal seizures.

Action Potentials↗
PubMed1999

[Physiopathology and etiology of epilepsy in children].

Epilepsy is an association of chronic disorders characterised by recurrence of paroxysmal manifestations related to synchronisation of brain neuron populations. The mechanism is still unknown and few clinical forms are reproduced by animal models. A causal cerebral lesion is identified in only one fourth of cases. The origin of epilepsy thus remains largely speculative, although natural and genetic factors, as well as lesions have been evidenced. Nevertheless, knowledge concerning the genes predisposing to epilepsy has opened the way to new treatments, and better identification of electroencephalographic changes that precede the onset of crises could allow surgery without resection, by neurophysiological treatment of epileptogenic foci.

Cerebral Cortex↗
PubMed1999

Impairment of G-protein-mediated signal transduction in the porcine coronary endothelium during rejection after heart transplantation.

BACKGROUND: Endothelial dysfunction is an early event leading to atherosclerosis. It also occurs after orthotopic heart transplantation and can be used to predict the development of intimal hyperplasia in the coronary artery wall. The present study was designed to assess the time course and specific alterations underlying endothelial dysfunction due to rejection after heart transplantation. METHODS: A porcine model of heterotopic heart transplantation was used. Preoperative serum typing for the class I antigen of the swine lymphocyte alloantigen was performed to ensure compatibility for this antigen. This permitted survival of the graft with a low grade rejection without immunosuppression. Rings (with or without endothelium) of epicardial coronary arteries of native and transplanted hearts were studied in organ chambers filled with modified Krebs-Ringer bicarbonate solution and compared 1, 30 and 60 days after transplantation. RESULTS: Myocardial contractility was normal in all grafts studied at 60 days after transplantation and all coronary arteries were patent. Myocardial biopsies showed the progression of rejection from day 1 to day 60 after implantation. All endothelium-dependent relaxations were normal one day after transplantation. Endothelium-dependent relaxations to serotonin and to the alpha 2-adrenergic agonist UK14304 (which both activate receptors coupled to Gi-proteins) and to sodium fluoride (a direct activator of G-proteins) were decreased 30 days after transplantation, while those to the calcium ionophore, A23187, and bradykinin were shifted to the right and those to ADP were normal. At 60 days, endothelium-dependent relaxations mediated by the Gi-protein pathway were decreased further while the concentration-relaxation curves to the other agonists were further shifted to the right. Endothelium-independent relaxations to the nitric oxide donor, Sin-1, were progressively reduced at 30 and 60 days, but maximal relaxations were maintained at 60 days. Histomorphometric studies showed a progressive increase in the percentage of coronary rings with intimal thickening from day 1 to day 60 after transplantation. CONCLUSIONS: The progressive endothelial dysfunction reported in this model of accelerated coronary atherosclerosis after transplantation without immunosuppression involves preferentially the pertussis-toxin-sensitive Gi-protein-mediated pathway. Endothelium-independent relaxations are decreased at 60 days, as are all other endothelium-dependent relaxations. Decreased endothelium-dependent vasodilatation may contribute to the development of coronary graft vasculopathy.

Adenosine Diphosphate↗
PubMed1999

Alteration of endothelium-dependent hyperpolarizations in porcine coronary arteries with regenerated endothelium.

The present study was designed to test the ability of regenerated endothelium to evoke endothelium-dependent hyperpolarizations. Hyperpolarizations induced by serotonin and bradykinin were compared in isolated porcine coronary arteries with native or regenerated endothelium, 4 weeks after balloon endothelial denudation. The experiments were performed in the presence of inhibitors of nitric oxide synthase (Nomega-nitro-L-arginine) and cyclooxygenase (indomethacin). The transmembrane potential was measured using conventional glass microelectrodes. Smooth muscle cells from coronary arteries with regenerated endothelium were depolarized in comparison with control coronary arteries from the same hearts. Spontaneous membrane potential oscillations of small amplitude or spikes were observed in some of these arteries but never in arteries with native endothelium. In coronary arteries from control pigs, both serotonin and bradykinin induced concentration-dependent hyperpolarizations. In the presence of ketanserin, 10 micromol/L serotonin induced a transient hyperpolarization in control coronary arteries. Four weeks after balloon denudation, the response to serotonin was normal in arteries with native endothelium, but the hyperpolarization was significantly lower in coronary arteries with regenerated endothelium. In control arteries, the endothelium-dependent hyperpolarization obtained with bradykinin (30 nmol/L) was reproducible. Four weeks after balloon denudation, comparable hyperpolarizations were obtained in coronary arteries with native endothelium. By contrast, in arteries with regenerated endothelium, the hyperpolarization to bradykinin became voltage-dependent. In the most depolarized cells, the hyperpolarization to bradykinin was augmented. The changes in resting membrane potential and the alteration in endothelium-dependent hyperpolarizations observed in the coronary arteries with regenerated endothelium may contribute to the reduced response to serotonin and the unchanged relaxation to bradykinin described previously.

Animals↗
PubMed1999

Metastatic salivary duct carcinoma to the uterus: report of a case diagnosed by cervical smear.

Metastasis to the uterus from extragenital sites is uncommon. We report on a rare case of salivary duct carcinoma (SDC) of the parotid gland with metastasis to the uterus, diagnosed by cervical smear. To the best of our knowledge, this is the first case reported in the literature. A 61-yr-old woman with a prior diagnosis of SDC was admitted to hospital with a fractured left humerus, back pain, and vaginal bleeding. A cervical smear and an endometrial aspiration were performed. The cervical smear showed numerous fragments and many isolated tumor cells in a clean background. The tumor cells were large and had abundant, granular/vacuolated cytoplasm. The nuclei were slightly pleomorphic, with fine chromatin and 1-2 small nucleoli. The malignant cells were morphologically identical to the primary tumor and correlated with the tumor in the endometrial aspiration. A diagnosis of metastatic salivary duct carcinoma was made. Although metastatic SDC to the uterus is rare, this possibility should be considered in the differential diagnosis of a positive cervical smear. This case also illustrates the importance of appropriate clinical history, including the knowledge of a primary tumor which may prevent unnecessary clinical investigations. Diagn. Cytopathol. 1999;21:271-275.

Carcinoma↗
PubMed1999

Cerebellar atrophy: an important feature of carbohydrate deficient glycoprotein syndrome type 1.

We report three children, all younger than 2 years of age, presenting with cerebellar atrophy related to carbohydrate-deficient glycoprotein syndrome type 1, an autosomal recessive metabolic disease. One patient had multisystem disease; two others had mental retardation with ataxia. In all cases the cerebellar atrophy was diagnosed on magnetic resonance imaging and, in one case, confirmed by autopsy. The cerebellar atrophy predominantly affected the anterior lobe. Vertical orientation of the tentorium cerebelli from the neonatal period in two cases suggests antenatal onset of the disease. Biological tests confirmed the diagnosis in all cases.

Atrophy↗
PubMed1999

[Hot water epilepsy: a benign and underestimated form].

BACKGROUND: Hot water epilepsy belongs to the group of reflex epilepsies. Seizures are provoked by hot water, due to the association of both cutaneous and heat stimuli. Described mainly in India and Japan, it seems to be rare in Europe where it occurs in young children. CASE REPORTS: Five infants aged between 6 months to 2 years had seizures during bathing with activity arrest, hypotonia and vasoactive modification. Sometimes clonic movements could be observed. The diagnosis was confirmed by EEG recorded during bath in the fives cases, with video for two of them. The course of the seizures and of the psychomotor development were favorable. CONCLUSION: Hot water epilepsy is a benign epilepsy. Its incidence could be underestimated because seizures can be confused with febrile convulsions or vagal fits.

Baths↗
PubMed1998

[Treatment of infantile spasms with vigabatrin as first-line therapy and in monotherapy: apropos of 70 infants].

BACKGROUND: Steroids (hydrocortisone or ACTH) still remain the usual treatment for infantile spasms (IS). However, since 1990, some authors have reported the efficacy of vigabatrin (VGB), especially in cases related to tuberous sclerosis. POPULATION AND METHODS: Seventy children with infantile spasms were treated by VGB first line monotherapy. Modalities of treatment and monitoring were the same for all children. VGB was given at the daily dose of 100 mg/kg during 1 week. If spasms persisted, the daily VGB dose was increased to 150 mg/kg during a 2nd week. In case of persistence of IS, on the 15th day, hydrocortisone was then added to VGB. Of the 70 infants, 39 were symptomatic and 31 cryptogenic. RESULTS: On VGB, 37 children (54%) stopped having IS within a mean 3.5 days. Response to VGB was different according to etiology. Among cryptogenic cases, 22 infants (71%) definitively stopped having spasms and only one relapsed. Among symptomatic cases, only 15 infants (38%) stopped having IS, and half (8/15) relapsed. VGB mean daily dose at cessation of spasms was 114 mg/kg. Side effects were transient drowsiness (27%) and agitation (12%). Mean follow-up was 10 months (1-24 months). Seventy-five percent of the infants presenting with a focus of spike after the 1st month of treatment relapsed. CONCLUSION: Infants with cryptogenic spasms have a good response to VGB monotherapy. When mental retardation is noticed before IS, and MRI is normal, there is no efficacy. In these cases, the best treatment seems to be prolonged corticotherapy associated with VGB.

Anti-Inflammatory Agents↗
PubMed1998

Electrochemical detection of nitric oxide production in perfused pig coronary artery: comparison of the performances of two electrochemical sensors.

In situ direct measurement of nitric oxide (NO) in biological media is now possible by means of electrochemical detection. In the literature, there are principally two amperometric approaches based on the direct oxidation of NO either on a sensor made from platinum/ iridium (Pt/Ir) alloy coated with a three-layered membrane or on a nickel porphyrin and Nafion-coated carbon fiber electrode. Nonetheless, the exact nature of the experimental amperometric signal obtained with the Pt/Ir system was never authenticated as being related to NO. This study compared responses of two sensors to the inhibition effect of Nomega-nitro-L-arginine (L-NA) as the amperometric signals produced by 5-hydroxytryptamine (5-HT) on isolated pig coronary preparations. These amperometric signals could be attributed to NO only for the nickel porphyrin and Nafion-coated carbon fiber electrode. Indeed, voltammetric characterization of the electrochemical response demonstrated only variations of the baseline current upon additions of either SNAP or NO on the Pt/Ir electrode instead of anodic peak current displayed at 0.63-0.75 V for the other system. Nitrites induced baseline current variations with the Pt/Ir electrode, similar to those obtained with S-nitroso-N-acetyl-dl-penicillamine (SNAP) or NO. This study highlights the potential hazards and pitfalls that may be associated with the use of a Pt/Ir sensor calibrated with SNAP solutions for the detection of NO production in various biological systems.

Alloys↗