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Biomedical subjects

P Deltenre

Publications and source records attributed to P Deltenre.

At least 19 recordsLinked to original sources
PubMed2006

Molecular mechanisms of cell death in periventricular leukomalacia.

OBJECTIVE: To investigate the cytokine-related molecular cascade leading to neural cell death in periventricular leukomalacia (PVL). METHODS: The authors explored potential tumor necrosis factor alpha (TNFalpha) signaling pathways in human brains with PVL and conducted in situ immunohistochemical investigations to search for possible expression of cytokine receptors in these brains. They also investigated likely links to molecules potentially involved in neurocytotoxicity, particularly pathways involving nitrosative-induced apoptosis. RESULTS: TNFalpha overexpression was associated with immune reactivity for p75TNFalphaR2 and p55TNFalphaR1 receptors in affected PVL areas. p75TNFalphaR2 labeling was intense on cerebrovascular endothelial cells in PVL areas, whereas no vascular p55TNFalphaR1 immunoreactivity was detected therein. Immune labeling for both receptors was detected on many white matter parenchymal cells. In contrast, there was no immune reactivity for either receptor in tissues taken from non-PVL areas. Additionally, in situ overexpression of inducible nitric oxide synthase was found in PVL brain regions where apoptotic cell death was detected. CONCLUSIONS: Both p75TNFalphaR2 and p55TNFalphaR1 receptors and nitric oxide may be implicated in the pathogenesis of periventricular leukomalacia.

Apoptosis↗
PubMed2005

Brain stem auditory potentials evoked by clicks in the presence of high-pass filtered noise in dogs.

This study evaluates the effects of a high-frequency hearing loss simulated by the high-pass-noise masking method, on the click-evoked brain stem-evoked potentials (BAEP) characteristics in dogs. BAEP were obtained in response to rarefaction and condensation click stimuli from 60 dB normal hearing level (NHL, corresponding to 89 dB sound pressure level) to wave V threshold, using steps of 5 dB in eleven 58 to 80-day-old Beagle puppies. Responses were added, providing an equivalent to alternate polarity clicks, and subtracted, providing the rarefaction-condensation potential (RCDP). The procedure was repeated while constant level, high-pass filtered (HPF) noise was superposed to the click. Cut-off frequencies of the successively used filters were 8, 4, 2 and 1 kHz. For each condition, wave V and RCDP thresholds, and slope of the wave V latency-intensity curve (LIC) were collected. The intensity range at which RCDP could not be recorded (pre-RCDP range) was calculated. Compared with the no noise condition, the pre-RCDP range significantly diminished and the wave V threshold significantly increased when the superposed HPF noise reached the 4 kHz area. Wave V LIC slope became significantly steeper with the 2 kHz HPF noise. In this non-invasive model of high-frequency hearing loss, impaired hearing of frequencies from 8 kHz and above escaped detection through click BAEP study in dogs. Frequencies above 13 kHz were however not specifically addressed in this study.

Acoustic Stimulation↗
PubMed2005

Transjugular intrahepatic portosystemic shunt in refractory ascites: a meta-analysis.

UNLABELLED: Transjugular intrahepatic portosystemic shunt (TIPS) is a more effective treatment for refractory ascites than large volume paracentesis (LVP), but the magnitude of its effect in terms of control of ascites, encephalopathy and survival has not been established. AIM: This meta-analysis compare TIPS to LVP in terms of control of ascites at 4 and 12 months, encephalopathy and survival at 1 and 2 years. RESULTS: Five randomized controlled trials involving 330 patients were included. In the TIPS group, control of ascites was more frequently achieved at 4 months (66% vs 23.8%, mean difference: 41.4%, 95% confidence interval (CI): 29.5-53.2%, P < 0.001) and 12 months (54.8% vs 18.9%, mean difference: 35%, 95% CI: 24.9-45.1%, P < 0.001), whereas encephalopathy was higher (54.9% vs 38.1%, mean difference: 17%, 95% CI: 7.3-26.6%, P < 0.001). Survival at 1 year (61.7% vs 56.5%, mean difference: 3.2%, 95% CI: -14.7 to 21.9%) and 2 years (50% vs 42.8%, mean difference: 6.8%, 95% CI: -10 to 23.6%) were not significantly different. CONCLUSIONS: TIPS is a more effective treatment for refractory ascites than LVP. However, TIPS increase encephalopathy and does not improve survival.

Aged↗
PubMed2005

[Experimental comparative evaluation of the functional capacities of ectopically grown fetal organs].

The interest for fetal organ, tissue, and cell implantation as therapeutic means in the treatment of some diseases is presently increasing. Hence, the aim of the present investigation was the comparative evaluation of the functional potential of ectopically grown fetal organs of different (ecto-, meso- and endodermic) origins. Unified operative model was the fetal organ fragment implantation into an ear subcutaneous pouch (without restoration of vascular and nervous links of the implant with the recipient organism). The implant isolation in vitro varied from 15 to 50 min. As control, intact animals and animals with streptozotocin diabetes and hepatic lesions due to the main bile duct ligature, were used. The implanted and ectopically grown fetal organs, though of different origins, developed functional activity. The best adult-like function was obtained in intestinal, gastric and cardiac implants, i.e. in organs with a cavity and a well developed self-regulation system. Poorer results were obtained in great digestive glandular implants--pancreas and liver. In the best cases when the implant function was very closed to the adult organ, a difference nevertheless was observed. The model of ectopic implantation of fetal organs may be useful for study of the organ and tissue function ontogenesis (up to the moment of natural ageing involution), for the evaluation of different isolated factor influence on organ and tissue physiology and pathology. Although being optimistic in respect to clinical application of fetal organ and cell implantation, this study does not prevent us from being cautions.

Animals↗
PubMed2004

Generalization of the generation of an MMN by illusory McGurk percepts: voiceless consonants.

OBJECTIVE: The existence of a Mismatch Negativity (MMN) evoked by McGurk percepts elicited by audiovisual syllables with constant auditory components has been previously demonstrated with voiced consonants [Clin. Neurophysiol. 113 (2002) 495]. The present study aimed at generalizing such results with voiceless consonants. In a first experiment, the MMN was computed using the classical subtraction method (standard minus deviant). Since results showed a possible contamination by exogenous visual components, a technique preventing from including those components in the differential waveform was used in a second experiment (deviant in sequence minus deviant presented alone). METHODS: Cortical evoked potentials were recorded using the oddball paradigm on eight adults in three experimental conditions (auditory alone, visual alone and audiovisual) for experiment one and in two conditions (visual alone and audiovisual) for experiment two. Obtaining illusory percepts was confirmed in additional psychophysical experiments. RESULTS: Significant MMNs were recorded in the three conditions of experiment one, whereas only the audiovisual condition of experiment two gave rise to a significant MMN. CONCLUSIONS: Provided that the MMN is computed with deviant stimuli only, the present results confirm the elicitation of genuine audiovisual MMN. Possible refractoriness effects and N2b confound have, however, to be controlled for in further studies.

Adolescent↗
PubMed2003

Facilitation of motor evoked potentials in ischemic stroke patients: prognostic value and neurophysiologic correlations.

OBJECTIVE: To investigate the predictive value of paired transcranial magnetic stimulation (TMS) at rest in stroke patients in comparison with the predictive value derived from data obtained by single TMS during facilitation. METHODS: Fifty-six patients with a single ischemic lesion and no electromyographic responses from single TMS in the resting affected hand muscles participated in the study. TMS assessment was performed 32 days post-stroke. It consisted of a single stimulation at maximal output during facilitation (controlateral hand grip and elbow flexion) and a paired-pulse stimulation at rest with two stimuli at maximal output at interstimulus intervals ranging from 15 to 100 ms. Two blind clinical assessments using the 'motricity index' were carried out 26 and 76 days post-stroke. RESULTS: Thirty-seven percent of patients were responsive to single TMS during facilitation, had better clinical scores at both evaluations and better clinical recovery. Fifty-four percent of patients responded to paired TMS, had better clinical scores at the second evaluation and better clinical recovery. All patients who responded to the single stimulation paradigm also responded to the paired one. CONCLUSIONS: A positive correlation was found between the responsiveness to both the TMS paradigms (facilitation procedure and paired stimulation) and clinical recovery. This underlines the importance of facilitation during single TMS in stroke patients and suggests that paired TMS at rest might supplement this procedure in stroke studies.

Adult↗
PubMed2003

The role of evoked potentials (EPs) in the assessment of the human central auditory nervous system (CANS).

This paper presents an overview of the use of EPs in the assessment of the CANS. Emphasis is laid on recent developments and research efforts centered on appraising how the auditory neural code is processed by the central pathways. It is shown how, in addition to their classical site-of-lesion testing role, EPs can, especially when combined with ecological (mostly speech-like) stimuli, yield highly valuable information on the neurophysiological processes leading to the perception of auditory objects as well as speech. Special space is devoted to the Mismatch Negativity that currently provides the only objective measure of the accuracy with which the CANS detects auditory and phonetic contrasts.

Auditory Diseases, Central↗
PubMed2002

Mismatch negativity evoked by the McGurk-MacDonald effect: a phonetic representation within short-term memory.

OBJECTIVES: The McGurk-MacDonald illusory percept is obtained by dubbing an incongruent articulatory movement on an auditory phoneme. This type of audiovisual speech perception contributes to the assessment of theories of speech perception. The mismatch negativity (MMN) reflects the detection of a deviant stimulus within the auditory short-term memory and besides an acoustic component, possesses, under certain conditions, a phonetic one. The present study assessed the existence of an MMN evoked by McGurk-MacDonald percepts elicited by audiovisual stimuli with constant auditory components. METHODS: Cortical evoked potentials were recorded using the oddball paradigm on 8 adults in 3 experimental conditions: auditory alone, visual alone and audiovisual stimulation. Obtaining illusory percepts was confirmed in an additional psychophysical condition. RESULTS: The auditory deviant syllables and the audiovisual incongruent syllables elicited a significant MMN at Fz. In the visual condition, no negativity was observed either at Fz, or at O(z). CONCLUSIONS: An MMN can be evoked by visual articulatory deviants, provided they are presented in a suitable auditory context leading to a phonetically significant interaction. The recording of an MMN elicited by illusory McGurk percepts suggests that audiovisual integration mechanisms in speech take place rather early during the perceptual processes.

Acoustic Stimulation↗
PubMed2002

Electrophysiology of spatial scene analysis: the mismatch negativity (MMN) is sensitive to the ventriloquism illusion.

OBJECTIVES: The ventriloquism effect is the tendency to underestimate the spatial separation between synchronous auditory and visual signals moderately separated in space. If, as it is thought, this effect is pre-attentive, it could modulate the mismatch negativity (MMN) that indexes the automatic, pre-attentive detection of deviant auditory stimuli rarely occurring in a sequence of standard stimuli. We assessed the existence of an MMN evoked by auditory and visual signals made up of standard sounds coming from the same location as the visual signal and deviant sounds coming from lateral deviations (20 or 60 degrees). As first observed in a behavioral study, a ventriloquism effect occurred for 20 degrees spatial separation but not for 60 degrees. METHODS: Cortical evoked potentials were recorded using the oddball paradigm on 8 adults in auditory alone and audiovisual conditions. RESULTS: In the auditory alone condition, each spatial localization contrast elicited a significant MMN. In the audiovisual condition, a significant MMN was only evoked for the 60 degrees contrasts. CONCLUSIONS: The MMN evoked by spatial separation contrasts (20 and 60 degrees) in the auditory alone condition was suppressed by the corresponding audiovisual condition only when the latter yielded a ventriloquism effect, suggesting that this effect occurs at an early perceptual level.

Acoustic Stimulation↗
PubMed2001

An original inner ear neuroepithelial degeneration in a deaf Rottweiler puppy.

Histopathological investigation was conducted on both inner ears from a 4.5-month-old Rottweiler puppy with electrophysiologically confirmed bilateral deafness. The lesions were restricted to the organ of Corti and spiral ganglion that both displayed severe degenerative changes. The outer hair cells were less affected than the inner hair cells. The number of spiral ganglion neurons was reduced, and remaining neurons were altered. The basal and middle cochlear turns were more affected than the apical one. The vestibules were normal. Immunostaining with calbindin, calretinin, S100A1 and S100A6 polyclonal antisera was helpful in identifying different cell-types in the degenerated cochlea. The early and severe spiral ganglion cell degeneration is an uncommon finding no matter the species. Such lesions bear significance within the frame of cochlear implants technology for deaf infants.

Animals↗
PubMed2001

Hemodynamic, metabolic and hormonal responses to oral glibenclamide in patients with cirrhosis receiving glucose.

BACKGROUND: In patients with cirrhosis, glucose may induce splanchnic and renal vasodilation. Since the antidiabetic sulfonylurea glibenclamide is known to induce splanchnic and renal vasoconstriction in portal hypertensive animals, this drug may inhibit glucose-induced hemodynamic responses in patients with cirrhosis. The aim of the present study was to investigate, in patients with cirrhosis, the short-term effects of glibenclamide on hemodynamic and humoral responses to glucose. METHODS: Patients were randomly assigned to receive either glibenclamide (5-mg tablet) or a placebo. All patients received an infusion of 10% glucose (62.5 ml/h for 12 h) that was started at the same time as glibenclamide or placebo administration. Studies were performed prior to and 90 min after glibenclamide or placebo. RESULTS: Glibenclamide (i.e. glibenclamide plus glucose) significantly increased plasma insulin concentrations and glycemia while placebo (i.e. glucose alone) significantly increased glycemia but did not change plasma insulin levels. Glibenclamide did not significantly change the hepatic venous pressure gradient while this value was significantly increased following glucose alone. Glibenclamide did not significantly change renal blood flow and glomerular filtration rate while glucose alone significantly increased renal blood flow without affecting the glomerular filtration rate. Glibenclamide significantly decreased cardiac index while glucose alone did not change this value. CONCLUSIONS: In patients with cirrhosis receiving glucose, glibenclamide blunted glucose-induced splanchnic and renal vasodilation. In addition, glibenclamide per se induced a decrease in cardiac index. These findings should be taken into account when glibenclamide is administered to patients with cirrhosis and type 2 diabetes.

Administration, Oral↗
PubMed2001

Factor V Leiden related Budd-Chiari syndrome.

BACKGROUND: The role of factor V Leiden as a cause of Budd-Chiari syndrome has only recently been described. AIMS: To assess the specific features of factor V Leiden related Budd-Chiari syndrome. PATIENTS: Sixty three consecutive patients with hepatic vein or terminal inferior vena cava thrombosis. METHODS: Standardised chart review. RESULTS: Factor V Leiden was found in 20 patients (31% (95% CI 20-43)). In the subgroup of patients with, compared with the subgroup without, factor V Leiden, a combination of prothrombotic states was more common (70% (95% CI 50-90) v 14% (95% CI 3-24)); inferior vena cava thrombosis was more frequent (40% (95% CI 19-61) v 7% (95% CI 0-14)); and distribution of initial alanine aminotransferase values was bimodal (almost normal or extremely increased) versus unimodal (p=0.003). Factor V Leiden accounted for four of five cases of massive ischaemic necrosis (transaminases >50-fold the upper limit of normal values) (p=0.014), and also for all three cases developing during pregnancy. Patients with and without factor V Leiden did not differ with regard to mortality, portosytemic shunting, or listing for liver transplantation. Hepatocellular carcinoma developed in two patients; both had factor V Leiden and indolent obstruction of the inferior vena cava. CONCLUSIONS: In patients with Budd-Chiari syndrome, factor V Leiden (a) is common; (b) precipitates thrombosis mostly when combined with another risk factor; (c) is associated with one of two contrasting clinical pictures: indolent thrombosis-particularly of the inferior vena cava-or massive ischaemic necrosis; and (d) is a major cofactor of Budd-Chiari syndrome developing during pregnancy.

Adult↗
PubMed2000

Connatal Pelizaeus-Merzbacher disease in two girls.

We report the clinical, radiological and electrophysiological signs in two unrelated girls with the connatal form of Pelizaeus-Merzbacher disease (PMD). MRI plays an important role in the diagnosis, demonstrating the virtual absence of myelination. PMD is classically described as an X-linked leukodystrophy. Our two cases reinforce the hypothesis of a possible autosomal recessive transmission of the connatal form of PMD in some families, as recently presented.

Diagnosis, Differential↗
PubMed1999

Mesalazine (5-aminosalicylic acid) induced chronic hepatitis.

BACKGROUND: Treatment of ulcerative colitis or Crohn's disease with sulphasalazine causes several adverse effects, including hepatitis. Sulphasalazine is cleaved by colonic bacteria into 5-aminosalicylic acid and sulphapyridine. Received wisdom was that 5-aminosalicylic acid was topically active, whereas sulphapyridine was absorbed and caused immunoallergic side effects. Mesalazine, a slow release formulation of 5-aminosalicylic acid, was expected to be a safe alternative. However, several cases of acute hepatitis have been reported. CASE REPORT: A 65 year old man had increased liver enzymes, anti-nuclear and anti-smooth muscle autoantibodies and IgG levels, and lesions of chronic hepatitis after 21 months of mesalazine treatment. Although liver dysfunction had been identified eight months earlier, simvastatin rather than mesalazine had been withdrawn, without any improvement. In contrast, liver enzyme and IgG levels became normal and autoantibodies disappeared after discontinuation of mesalazine administration. CONCLUSION: Contrary to initial expectations, mesalazine can cause most of the sulphasalazine induced adverse effects, and hepatic side effects may be almost as frequent. When liver dysfunction occurs, mesalazine administration should be discontinued to avoid the development of chronic hepatitis and liver fibrosis.

Aged↗
PubMed1997

Temporal distortion products (kernel slices) evoked by maximum-length-sequences in auditory neuropathy: evidence for a cochlear pre-synaptic origin.

When special pseudo-random stimuli sequences (maximum length sequences: MLS) are combined with a deconvolution analysis technique, it is possible to derive new evoked potential components that are called kernels. The kernels give a measure of the temporal interactions that take place between the responses to successive stimuli. This may provide an objective neurophysiological test for the exploration of a dimension of hearing which has hitherto been limited to psychophysical methods. Until now, auditory short-latency kernels obtained by the MLS method have been related to the late portion of the brainstem auditory evoked potential (BAEP), suggesting that temporal interactions occur rather late in the auditory pathways. We report 4 children without any BAEP neural components, who all retained isolated cochlear microphonic potentials. Three of them produced click-evoked otoacoustic emissions and two of them demonstrated only moderately impaired audiometric thresholds. This combination of absent BAEP neural components with preserved otoacoustic emissions and cochlear microphonic potential corresponds to a peculiar pattern of auditory dysfunction recently coined "auditory neuropathy'. All 4 children exhibited well-defined kernels at latencies consistent with the microphonic potential. These data indicate that the cochlea itself can generate kernels at a presynaptic level. They open up the question of the identification of the physiological site(s) responsible for the generation of MLS-evoked kernels.

Adolescent↗
PubMed1997

Auditory neuropathy: a report on three cases with early onsets and major neonatal illnesses.

We report 3 children without any brainstem auditory evoked potential (BAEP) neural component who all retained isolated cochlear microphonic potentials as well as click-evoked otoacoustic emissions. Two of them demonstrated only moderately impaired audiometric thresholds. These features correspond to a peculiar pattern of auditory dysfunction recently coined "auditory neuropathy'. In contrast with the published previous cases of auditory neuropathy presenting with an acquired hearing deficit as children or young adults, all 3 children had a history of major neonatal illness and the auditory neuropathy was already demonstrated in the first months of their lives.

Age of Onset↗