PubMed Health⌕ Search

Biomedical subjects

J P Gagné

Publications and source records attributed to J P Gagné.

18 recordsLinked to original sources
PubMed2001

Estimation of dissolved organic carbon (DOC) concentrations in nanoliter samples using UV spectroscopy.

A simple analytical system has been developed and tested for estimating dissolved organic carbon (DOC) concentrations in nanoliter samples of sediment porewaters. The system consists of a loop injector that introduces 200 nL of sample directly into the capillary tubing connected to a scanning UV-VIS detector equipped with a 35-nanoliter capillary flowcell. Analysis of DOC by spectroscopic and high-temperature catalytic oxidation (HTCO) methods on the same samples showed a strong linear correlation between UV absorbance at 254 nm and HTCO-DOC concentration, allowing the DOC quantification. The simplicity and the robustness of the UV system allow DOC measurements in the field at a rate of 30 samples/h. We have used the UV system successfully for determining high-resolution distributions of porewater DOC concentrations in sediments at millimeter scales.

Carbon↗
PubMed2001

Analysis of ADP-ribose polymer sizes in intact cells.

Poly(ADP-ribose) is a polymer (pADPr) that is synthesized by poly (ADP-ribose) polymerases in response to DNA damaging agents. For instance, chemical alkylating agents such as MNNG or physical stimulation of cells by gamma-rays are well known to induce pADPr synthesis. PARPs are members of a growing family of enzymes which includes PARP-1, PARP-2, S-PARP-1, tankyrase and V-PARP. The association of PARP-1 and PARP-2 in DNA damage signaling pathways has been characterized, but tankyrase and V-PARP seem to be independent of DNA repair mechanisms. Poly(ADP-ribosyl)ation leads to heterogenous chain lengths of up to 200 units (mers) in vitro. While most of these will be covalently bound to proteins, they may be released under alkaline conditions for analysis. Previous immunological methods such as immunoblots showed that about 60-70% of the 6-8 mers pADPr were lost during fixation and that the very short pADPr (2-5 mers) were very weakly bound to the membrane. Furthermore, detection of cellular pADPr using enzyme-linked immunosorbent assay (ELISA) revealed that some molecules of pADPr are also lost during fixation and washings. This phenomenon leads to underestimation of the short pADPr population in cells. Thus, evaluating which pADPr sizes are present in cells and tissues becomes critical. We report here the development of a new highly sensitive immunological method to detect synthesized pADPr sizes distribution in intact cells.

Animals↗
PubMed2000

What is treatment evaluation research? What is its relationship to the goals of audiological rehabilitation? Who are the stakeholders of this type of research?

Three topics related to treatment evaluation research in audiological rehabilitation are discussed. First, the International Classification of Impairments, Activities and Participation (ICIDH-2) (World Health Organization, 1999) is described and proposed as a general conceptual framework for the design of intervention and research activities in audiological rehabilitation. Second, the three main domains of treatment evaluation research (efficacy, effectiveness, and efficiency) are briefly outlined. Third, the various consumers of treatment evaluation research in audiological rehabilitation are identified. Also, the domains of treatment evaluation research that are of interest to each of these consumer groups are presented. An analysis of the main interests of each group of stakeholders suggests that, at present, evaluative research in audiological rehabilitation does not adequately meet the needs of all stakeholders. Nevertheless, the future of evaluative research in audiological rehabilitation is promising, for several reasons: 1) research related to audiological rehabilitation is being actively pursued especially in the areas of treatment efficacy and treatment effectiveness; 2) the audiological rehabilitation community should be able to adapt its endeavors to the proposed conceptual framework of health conditions fairly easily (ICIDH-2; World Health Organization, 1999); 3) the research needs of the primary stakeholders of audiological rehabilitation are known; and 4) there is a keen interest within the professional community to develop this area of research. All of these conditions are propitious for setting the research agenda of treatment evaluation research in audiological rehabilitation for the next several years.

Audiology↗
PubMed2000

Optimal outcome measures, research priorities, and international cooperation.

The participants in the Eriksholm Workshop on "Measuring Outcomes in Audiological Rehabilitation Using Hearing Aids" debated three issues that are reported in this article. First, it was agreed that the characteristics of an optimal outcome measure vary as a function of the purpose of the measurement. Potential characteristics of outcome self-report tools for four common goals of outcome measurement are briefly presented to illustrate this point. Second, 10 important research priorities in outcome measurement were identified and ranked. They are presented with brief discussion of the top five. Third, the concept of generating a brief universally applicable outcome measure was endorsed. This brief data set is intended to supplement existing outcome measures and to promote data combination and comparison across different social, cultural, and health-care delivery systems. A set of seven core items is proposed for further study.

Correction of Hearing Impairment↗
PubMed1999

Auditory sequential organization among children with and without a hearing loss.

The present investigation examined the ability of children with and without a hearing loss to correctly reproduce sequences of acoustic stimuli that varied in number, temporal spacing, and type. Forty-eight children took part in the investigation. They were divided into four groups: two groups of 6- and 7-year-old children, 12 with normal hearing and 12 with a sensorineural hearing loss; and two groups of 9- and 10-year-old children, 12 with normal hearing and 12 with a sensorineural hearing loss. All of the children completed auditory temporal sequencing tasks with verbal (/ba/ and /da/) and nonverbal (a 1-kHz pure tone and a wide band noise) acoustic stimuli. For the 6- and 7-year-old children, the results revealed a significant difference between the children with a hearing loss and their peers with normal hearing for immediate recall of verbal sequences. There were no significant differences in performance between the children with a hearing loss and their peers with normal hearing on the nonverbal sequencing tasks or on the nonverbal and verbal memory span tasks. For the 9- and 10-year-old children, the results did not show any significant differences in performance between the two groups of children for the reproduction of sequences containing more than two verbal or nonverbal elements nor for the auditory memory span task when the sequences consisted of verbal stimuli. For the recall of two verbal stimuli with a variable interstimulus interval (ISI) duration, the results showed that the children with a hearing loss experienced more difficulty than the children with normal hearing. Overall, the results indicated that on the auditory sequential organization tasks, the poorer performance of the children with a hearing loss is likely attributable to auditory perceptual processing deficits rather than to poorer short-term memory capabilities. Also, an analysis of the data revealed that the older children obtained significantly better results than the younger children on auditory sequential organization tasks.

Auditory Threshold↗
PubMed1999

Some limitations of evaluative investigations based solely on normed outcome measures.

The present article argues that evaluative research in audiologic rehabilitation should be consistent with contemporary conceptual frameworks of rehabilitation. Moreover, comprehensive evaluative research investigations should include an evaluation of (1) the process of intervention and (2) the impacts and consequences of the intervention program. An approach to rehabilitation based on the principle that intervention should be viewed as a solution-centered problem-solving process is outlined. Then, three illustrative cases are described and compared from the perspective of traditional evaluative research paradigms and from the perspective that audiologic rehabilitation is a solution-centered problem-solving process. Some shortcomings of traditional approaches to evaluative research are discussed. Finally, some guidelines that could lead to the development of comprehensive evaluative research in rehabilitation are outlined.

Aged↗
PubMed1998

Reflections on evaluative research in audiological rehabilitation.

Changes in service delivery triggered by current conceptualizations of rehabilitation require an accompanying paradigm shift in the approaches used to evaluate the effectiveness of intervention programs in audiological rehabilitation. The present article outlines three fundamental principles of contemporary rehabilitative audiology that have implications concerning the way that audiological rehabilitation services should be conceived and dispensed, as well as the way in which comprehensive evaluative research investigations should be designed and conducted. Traditional treatment efficacy paradigms used to assess the effectiveness of intervention programs in rehabilitative audiology are critiqued. Finally, factors that should guide the development of comprehensive evaluative research paradigms which are consistent with current models of intervention in audiological rehabilitation are outlined.

Correction of Hearing Impairment↗
PubMed1997

[Congenital duodenal diaphragm in an adult associated with an abnormal location of Vater's ampulla: a case report and review of the literature].

Web-related duodenal obstruction in the adult is rare, so is the anomalous location of the ampulla of Vater in the third part of the duodenum. A woman who harboured both anomalies is described and the literature reviewed. The diagnosis, often made at laparotomy, mandates an exploratory duodenotomy. The best treatment consists of partial excision of the web and transverse closure of the duodenum. A duodenojejunostomy or duodenoduodenostomy, or both, are acceptable therapies. The anomalous location of the ampulla of Vater in the third part of the duodenum does not require treatment.

Ampulla of Vater↗
PubMed1993

Aerodynamic assessment of the speech of adults undergoing multichannel cochlear implantation.

This investigation was designed to evaluate the aerodynamic characteristics of the speech of adult multichannel cochlear implant (Nucleus, 21-channel) recipients. Five adults with an acquired profound sensorineural hearing loss were tested before implantation, immediately following implantation, and 3, 6, 9, and 12 months after implantation. A commercially available computerized pressure-flow instrumentation system was employed to assess the respiratory, laryngeal, velopharyngeal, and oral articulatory subsystems of speech of the implantees. The results of the investigation indicated 1) a slight increase in airflow rate values for sustained vowel /a/phonation after implantation, 2) a slight increase in duration of sustained vowel phonation from the preimplant period to the last postimplant period, 3) an increase in laryngeal airway resistance after implantation that resulted from a larger increase in estimated transglottal pressure than in transglottal airflow, 4) maintenance of normal velopharyngeal closure in oral-nasal contrastive contexts, and 5) slight increases in oral orifice area for fricative syllable utterances following implantation. Individual strategies for coordinated control of the speech mechanism appear to be potent variables to consider when assessing speech production.

Adult↗
PubMed1992

Comparison of two methods for estimating the sensation level of amplified speech.

Several methods have been proposed to estimate the sensation level (SL) at which children receive amplified speech from their hearing aids. The present study compared the SL estimates obtained with two such methods: (1) a sound field aided audiogram approach, and (2) an electroacoustic approach that incorporated the use of a probe tube microphone system (Seewald, Ross, & Stelmachowicz, 1987). Sound field aided thresholds were obtained for 13 hearing-impaired subjects at eight audiometric frequencies. For the electroacoustic approach, in situ thresholds were obtained using a button-type hearing aid receiver attached to a custom earmold. Real ear aided responses were measured using a 70 dB RMS speech-weighted composite noise signal (Frye, 1986). A comparison of the frequency-specific SL estimates derived from the two different methods revealed that the sound field aided audiogram approach yielded higher SL estimates for 74% of the individual comparisons. A detailed analysis of the findings obtained from two subjects suggested that when the results of the two methods did not agree, the differences were due to an interaction between signal level and the unique input/output characteristics of the subjects' hearing aids. A precautionary measure is suggested for those who wish to use sound field aided threshold data to estimate the SLs at which children receive amplified conversational speech.

Adolescent↗
PubMed1992

Signal delivery/real ear measurement system for hearing aid selection and fitting.

This report describes a signal delivery/real ear measurement system for application in the hearing aid selection and fitting process. This signal delivery/real ear measurement system provides a means for quantifying a listener's auditory characteristics (e.g., thresholds, loudness discomfort levels) in a manner that is compatible with electroacoustic measures of hearing aid performance. The signal delivery/real ear measurement system consists of a button-type hearing aid receiver coupled to the listener's personal earmold, and a probe tube microphone system to measure the signal level within the occluded ear canal. This signal delivery/real ear measurement system was used to measure detection thresholds and loudness discomfort levels in severe/profoundly hearing-impaired school-age children, with results indicating good test-retest reliability in behavioral responses. The findings presented in this report relate to the intersession electroacoustic variability associated with this instrumentation. In addition, the potential application of this or a similar system for measuring real ear to 2-cc coupler difference values is illustrated and discussed.

Acoustic Impedance Tests↗
PubMed1991

An evaluation of CAST: a Computer-Aided Speechreading Training program.

This study assessed the effectiveness of CAST (Computer-Aided Speechreading Training program). Two groups of 8 normal-hearing adults completed a pretraining visual speech perception test protocol that consisted of a Visual-Consonant Recognition Test, a test of Sentence Understanding Without Context, a test of Sentence Understanding With Context, and a semiautomated modified Continuous Discourse Tracking activity available with CAST. One group completed the CAST program. A posttraining test protocol was administered to the subjects 2 weeks following the maximum time provided to complete the training program (i.e., 10 weeks). Independent t tests revealed no differences between the control group and the experimental group in the percentage improvement score obtained on the following measures: viseme recognition score, Sentence Understanding Without Context (key word and total word recognition scores), and Sentence Understanding With Context (key word recognition score). Significant differences between the groups were found for the total word recognition score on the Sentence Understanding With Context test and the CAST modified Continuous Discourse Tracking activity. The results indicate that CAST was most effective in developing aspects of synthetic visual speech perception skills.

Adult↗
PubMed1991

Effectiveness of an intensive speech perception training program for adult cochlear implant recipients.

A staggered multiple baseline single-subject experimental design was used to assess the effectiveness of a postimplant intensive aural rehabilitation program. Four adults with an acquired profound hearing loss were provided with a Nucleus 22-channel cochlear implant. The subjects completed a speech perception test protocol once before their cochlear implant operation and at 3-month intervals for a period of 12 months postimplantation. Each subject participated in a 12-week postimplant intensive aural rehabilitation program. A comparison of the prerehabilitation and postrehabilitation results failed to reveal any systematic improvements in performance on the speech perception tests that could be attributed unequivocally to the aural rehabilitation program.

Adult↗
PubMed1989

Relative effectiveness of three repair strategies on the visual-identification of misperceived words.

Experimental videotapes were used to assess the effectiveness of three repair strategies: (1) repetitions, (2) synonyms, and (3) paraphrases. Three groups of normal-hearing adults viewed one of three videotapes. The same 50 test-words were used on each videotape. Each test-item consisted of three stimuli: a test-word, a stimulus that incorporated the repair strategy under investigation, and a repetition of the initial test-word. Each videotape displayed one of the three repair strategies under investigation. The subjects were required to identify test-words presented in a visual-only mode. The results indicated that the performance of the subjects who were provided with synonyms or paraphrases was significantly better than the performance of the subjects who were shown repetitions. Also, subjects who were shown paraphrases performed significantly better than those who were shown synonyms. These findings indicate that repair strategies that incorporate the use of substitute stimuli such as synonyms and paraphrases may be more effective than the simple repetition of the misperceived stimulus.

Adult↗
PubMed1988

Resonance-frequency discrimination.

Measurements of the just-noticeable change in resonance frequency delta Fr of a second-order filter are reported. The source signal was either periodic, with or without a smooth change in fundamental frequency, or it was random white noise. These differences in the nature of the source had little effect on delta Fr. Over the investigated ranges of reference resonance frequency (Fr = 300 to 2000 Hz) and filter selectivity (Q = 1 to 36), the results are well summarized by delta Fr = 0.079 Fr/square root Q. The data were used to evaluate filter-bank models employing different filter shapes and performance-prediction schemes. A good fit to the resonance-discrimination data was obtained with filters derived in a masking study by Patterson [J. Acoust. Soc. Am. 55, 802-809 (1974)] and with performance based on use of the maximum level difference over all bands. The latter finding indicates that listeners may not make optimal use of small level differences distributed over multiple bands.

Acoustic Stimulation↗
PubMed1988

Excess masking among listeners with a sensorineural hearing loss.

Three experiments were conducted to determine whether listeners with a sensorineural hearing loss exhibited greater than normal amounts of masking at frequencies above the frequency of the masker. Excess masking was defined as the difference (in dB) between the masked thresholds actually obtained from a hearing-impaired listener and the expected thresholds calculated for the same individual. The expected thresholds were the power sum of the listener's thresholds in quiet and the average masked thresholds obtained from a group of normal-hearing subjects at the test frequency. Hearing-impaired listeners, with thresholds in quiet ranging from approximately 35-70 dB SPL (at test frequencies between 500-3000 Hz), displayed approximately 12-15 dB of maximum excess masking. The maximum amount of excess masking occurred in the region where the threshold in quiet of the hearing-impaired listener and the average normal masked threshold were equal. These findings indicate that listeners with a sensorineural hearing loss display one form of reduced frequency selectivity (i.e., abnormal upward spread of masking) even when their thresholds in quiet are taken into account.

Acoustic Stimulation↗
PubMed1987

Simulation of sensorineural hearing impairment.

A hearing loss simulation system (HELOS) was designed and constructed to simulate various aspects of sensorineural hearing impairment. The theoretical bases for HELOS were several threshold and suprathreshold auditory phenomena typically exhibited by people with sensorineural hearing losses. In addition to providing differential attenuation of acoustic signals across the frequency range, HELOS simulated loudness recruitment, loudness discomfort thresholds, reduced dynamic range, and reduced frequency selectivity. Three basic audiometric configurations were chosen to investigate the effects of the aforementioned components of a sensorineural hearing impairment on the auditory perception of speech. They were: (1) a sloping high-frequency hearing loss; (2) a flat, severe hearing loss; (3) a severe/profound hearing loss. The battery of tests administered to a group of normal-hearing adults consisted of pure-tone audiometry and PB-word recognition tests, as well as vowel and consonant identification tests. For comparable audiometric configurations, the results from the speech-perception tests were in good agreement with the published results of similar tests administered to persons with sensorineural hearing losses.

Adult↗