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Biomedical subjects

K Tremblay

Publications and source records attributed to K Tremblay.

15 recordsLinked to original sources
PubMed2006

Association study between the CX3CR1 gene and asthma.

CX3CR1, a fractalkine receptor, mediates cell-adhesive and migratory functions in inflammation. Based on CX3CR1 expression observed in bronchial tissues of asthmatic subjects, we hypothesized that genetic variation at this locus may affect susceptibility to asthma. We carried out an association study and a haplotypic analysis with selected polymorphisms of the CX3CR1 in a familial asthmatic sample from a founder population. Genetic analyses performed by FBAT software showed five CX3CR1 single nucleotide polymorphisms (rs938203, rs2669849, rs1050592, T280M and V249I) with significant associations between their common alleles and asthma (P<0.004) in a dominant model. A haplotype formed with common alleles of rs1050592, T280M and V249I is also overtransmitted in asthmatic subjects (P=0.005) under a dominant model. The associations of V249I and rs2669849 have been validated in an independent case-control sample. For V249I, odds ratios (OR) are 2.16 (common homozygous) and 2.11 (heterozygous) in dominant model (P=0.031). For rs2669849, OR are 2.75 (common homozygous) and 1.86 (heterozygous) in additive model (P=0.007) and dominant model (P=0.059). These results suggest an asthma protective effect of the minor alleles in healthy control carriers. Further functional studies of CX3CR1 are needed to document its role in the pathophysiology of asthma.

Adolescent↗
PubMed2003

The use of genomics and proteomics to understand oocyte and early embryo functions in farm animals.

Oocyte maturation, a simple and visible phenomenon, is about to be transformed into a complex and not so visible molecular cascade leading to the marking of the following generation. The study of oocyte maturation in mammals is progressively changing towards a more molecular approach. This review addresses the main challenges in the study of RNA extraction and quantification in oocytes and embryos as well as the importance of the mRNA maturation. The identification of specific genes in oocytes and embryos is now possible with the use of powerful tools, such as library analysis or subtractions, DNA array, comparative analysis of databanks from other mammals or animals and two-dimensional gel electrophoresis analysis. Finally, RNA interference is a useful tool for studying gene function by knocking out the activity of specific genes and will be used in oocytes and embryos.

Animals↗
PubMed2001

Plasticity in the adult human central auditory system: evidence from late-onset profound unilateral deafness.

Experience-related changes in central nervous system (CNS) activity have been observed in the adult brain of many mammalian species, including humans. In humans, late-onset profound unilateral deafness creates an opportunity to study plasticity in the adult CNS consequent to monaural auditory deprivation. CNS activity was assessed by measuring long-latency auditory evoked potentials (AEPs) recorded from teens and adults with late-onset (post-childhood) profound unilateral deafness. Compared to monaurally stimulated normal-hearing subjects, the AEPs recorded from central electrode sites located over auditory cortical areas showed significant increases in inter-hemispheric waveform cross-correlation coefficients, and in inter-hemispheric AEP peak amplitude correlations. These increases provide evidence of substantial changes from the normal pattern of asymmetrical (contralateral > ipsilateral amplitude) and asynchronous (contralateral earlier than ipsilateral) central auditory system activation in the normal-hearing population to a much more symmetrical and synchronous activation in the unilaterally deaf. These cross-sectional analyses of AEP data recorded from the unilaterally deaf also suggest that the changes in cortical activity occur gradually and continue for at least 2 years after the onset of hearing loss. Analyses of peak amplitude correlations suggest that the increased inter-hemispheric symmetry may be a consequence of changes in the generators producing the N (approximately 100 ms peak latency) potential. These experience-related changes in central auditory system activity following late-onset profound unilateral deafness thus provide evidence of the presence and the time course of auditory system plasticity in the adult brain.

Adolescent↗
PubMed2001

Central auditory plasticity: changes in the N1-P2 complex after speech-sound training.

OBJECTIVE: To determine whether the N1-P2 complex reflects training-induced changes in neural activity associated with improved voice-onset-time (VOT) perception. DESIGN: Auditory cortical evoked potentials N1 and P2 were obtained from 10 normal-hearing young adults in response to two synthetic speech variants of the syllable /ba/. Using a repeated measures design, subjects were tested before and after training both behaviorally and neurophysiologically to determine whether there were training-related changes. In between pre- and post-testing sessions, subjects were trained to distinguish the -20 and -10 msec VOT /ba/ syllables as being different from each other. Two stimulus presentation rates were used during electrophysiologic testing (390 msec and 910 msec interstimulus interval). RESULTS: Before training, subjects perceived both the -20 msec and -10 msec VOT stimuli as /ba/. Through training, subjects learned to identify the -20 msec VOT stimulus as "mba" and -10 msec VOT stimulus as "ba." As subjects learned to correctly identify the difference between the -20 msec and -10 msec VOT syllabi, an increase in N1-P2 peak-to-peak amplitude was observed. The effects of training were most obvious at the slower stimulus presentation rate. CONCLUSIONS: As perception improved, N1-P2 amplitude increased. These changes in waveform morphology are thought to reflect increases in neural synchrony as well as strengthened neural connections associated with improved speech perception. These findings suggest that the N1-P2 complex may have clinical applications as an objective physiologic correlate of speech-sound representation associated with speech-sound training.

Adult↗
PubMed2001

Long-term habituation of the speech-elicited mismatch negativity.

A significant issue in the use of the mismatch negativity evoked potential (MMN) concerns its low signal-to-noise ratio (SNR). One can improve the noise level by increasing the number of samples included in the averaged response. However, improvement achieved in this way assumes that the signal, the MMN, remains stable for extended test times, an assumption which has not been tested. If the MMN is not stable, or exhibits habituation over the test session, then SNR would be adversely affected. MMN response magnitude was measured in 5-min intervals over the course of a test session in response to various speech syllable contrasts. Significant long-term habituation of MMN was observed for all three subject populations tested: young adults, school-age children, and guinea pigs. The time course of the habituation and the stimulus conditions under which it occurs have important implications for research and clinical applications of the MMN. Recording procedures that minimize habituation effects may be used to advantage to improve the signal-to-noise ratio of the MMN.

Adolescent↗
PubMed1998

The time course of auditory perceptual learning: neurophysiological changes during speech-sound training.

Here we report that training-associated changes in neural activity can precede behavioral learning. This finding suggests that speech-sound learning occurs at a pre-attentive level which can be measured neurophysiologically (in the absence of a behavioral response) to assess the efficacy of training. Children with biologically based perceptual learning deficits as well as people who wear cochlear implants or hearing aids undergo various forms of auditory training. The effectiveness of auditory training can be difficult to assess using behavioral methods because these populations are communicatively impaired and may have attention and/or cognitive deficits. Based on our findings, if neurophysiological changes are seen during auditory training, then the training method is effectively altering the neural representation of the speech/sounds and changes in behavior are likely to follow.

Acoustic Stimulation↗
PubMed1998

The need for a coherent curriculum and supported infrastructure in health informatics education--the HEALNet experience. Health Evidence Application and Linkage Network.

The Canadian National Centres of Excellence Network, Health Evidence Application and Linkage Network (HEALNet) is a network linking universities, the private sector and other public sector organisations in supporting research and fostering commercial opportunities. Its aim is to develop high quality health care decision support methodologies and tools that support the transfer of research evidence into practice. The HEALNet education program aims to support the training of highly qualified personnel as well as the development of educational approaches so that health personnel can better exploit such methodologies and decision support tools given the new opportunities of information technology. There is a need to draw from the different types of expertise within HEALNet to provide an integrated curriculum. At the same time, there is a concern regarding the lack of a coherent infrastructure in health informatics in many Canadian medical schools.

Canada↗
PubMed1997

Central auditory system plasticity: generalization to novel stimuli following listening training.

Behavioral perceptual abilities and neurophysiologic changes observed after listening training can generalize to other stimuli not used in the training paradigm, thereby demonstrating behavioral "transfer of learning" and plasticity in underlying physiologic processes. Nine normal-hearing monolingual English-speaking adults were trained to identify a prevoiced labial stop sound (one that is not used phonemically in the English language). After training, the subjects were asked to discriminate and identify a prevoiced alveolar stop. Mismatch negativity cortical evoked responses (MMN) were recorded to both labial and alveolar stimuli before and after training. Behavioral performance and MMNs also were evaluated in an age-matched control group that did not receive training. Listening training improved the experimental group's ability to discriminate and identify an unfamiliar VOT contrast. That enhanced ability transferred from one place of articulation (labial) to another (alveolar). The behavioral training effects were reflected in the MMN, which showed an increase in duration and area when elicited by the training stimuli as well as a decrease in onset latency when elicited by the transfer stimuli. Interestingly, changes in the MMN were largest over the left hemisphere. The results demonstrate that training can generalize to listening situations beyond those used in training sessions, and that the preattentive central neurophysiology underlying perceptual learning are altered through auditory training.

Adolescent↗
PubMed1994

Organizational renewal and strategic planning: a winning combination.

Several approaches to organizational renewal have been described, but few are reported for health care institutions in Canada. In contrast, approaches to strategic planning in health care facilities have been well documented. From our experience over the past six years, the theory and practice of organizational renewal complement the focused activities of strategic planning. This combination can be an effective means to enhance organizational performance, employee commitment and a shared vision among the various stakeholders within the hospital and community. This article outlines the process and benefits that can accrue through such efforts. It demonstrates how the investment of organizational renewal strategies can produce sustainable, operational and strategic planning benefits for community hospitals.

Hospital Restructuring↗