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Biomedical subjects

F Gagnon

Publications and source records attributed to F Gagnon.

At least 37 records · Page 2Linked to original sources
PubMed1996

Catalytic and non-catalytic forms of the neurotrophin receptor xTrkB mRNA are expressed in a pseudo-segmental manner within the early Xenopus central nervous system.

The induction of anterior-posterior and medio-lateral patterning within the Xenopus neural plate leads to the rapid establishment of a functional nervous system. Here we describe two Xenopus TrkB neurotrophin receptor genes which are expressed in discrete sets of neuroblasts during this developmental process. The xTrkB mRNAs encode both catalytic and non-catalytic receptors and exhibit membrane-spanning-domain proximal splicing. Expression begins at neural tube closure within the trigeminal ganglion and within the Rohon-Beard neurons of the dorsal spinal cord, providing an excellent dorsal marker of early neural tube patterning. Expression occurs later in the facial ganglia and possibly within the Kolmer-Agduhr neurons. The predominant xTrkB transcripts within the trigeminal and Rohon-Beard neurons and the exclusive early transcripts of the facial ganglia encode C-terminally truncated non-catalytic receptors. Such Trk mRNAs have previously been observed in rodents. However, our observations suggest that they may play a specific role during early development. Anterior-posterior segmentation of the neural tube occurs rostrally within the prospective brain, but previous studies have suggested that segmentation does not extend caudally into the spinal cord. We show that the xTrkB positive Rohon-Beard neurons of the spinal cord do in fact display clear segmental groupings soon after neural tube closure. This is consistent with a role for segmentation in the anterior-posterior patterning of the trunk central nervous system.

Amino Acid Sequence↗
PubMed1995

Cognitive-behavioral treatment of obsessions.

Three patients with obsessive-compulsive disorder whose major complaints were obsessional thoughts with cognitive neutralization as opposed to overt rituals were treated with a cognitive-behavioral package. Cognitive neutralization involves both cognitive rituals and a variety of less ritualized coping strategies all designed to remove the thought and decrease discomfort. In a departure from earlier case studies, the patients were treated in a multiple baseline design across subjects. All three patients reported decreased discomfort and improved their professional and/or interpersonal functioning. Gains were maintained at follow-up (8 to 11 months).

Adaptation, Psychological↗
PubMed1995

Long term stability of somatosensory evoked potentials and the effects of microgravity.

BACKGROUND: Exposure to microgravity causes a height increase of up to 70 mm that places traction on the spine and may possibly lead to spinal cord dysfunction. Somatosensory evoked potentials (SSEP) have been widely used to monitor spinal cord function. This study was carried out to determine the long-term stability of the latency of SSEP's in individual subjects and the feasibility of recording SSEP's in a microgravity environment. METHODS: Baseline values and variability of the latency of the cortical evoked potentials were established in seven subjects over periods of 1-2.5 years. These values were then compared with measurements made in six of the subjects during periods of microgravity on a KC-135 aircraft. The latency of the cortical potentials was also measured in the evening and in the morning before rising in a separate group of seven subjects, to determine whether there was any diurnal variation. RESULTS: The mean coefficient of variance of the latency of the SSEP was approximately 1.5% of the latency, and there were no changes in the latency over the period studied. There was no evidence of diurnal variation in the latency of the cortical SSEP. Satisfactory recordings of the SSEP were obtained in five of six subjects tested in microgravity. In three of these five subjects there was a significant decrease in the latency of the cortical SSEP in microgravity. CONCLUSIONS: In individual subjects the latency of the cortical SSEP varies within very small limits (1.5%) over 1-2.5 years. The results demonstrate the feasibility of recording SSEP's in the microgravity state. They show that relatively small changes (2-3 ms) in the latency of the SSEP can be detected when prior baseline values are established for each subject. The reason for the decrease in latency of the cortical SSEP in some subjects on the KC-135 is not known.

Adult↗
PubMed1995

Vibration and noise in pediatric emergency transport vehicles: a potential cause of morbidity?

BACKGROUND: Noise and vibration are stressors that may adversely affect the well-being of infants and children being transported between facilities. Although the problem has been recognized, little has been done to rectify the situation. HYPOTHESIS: That noise levels in transport incubators during use in transport vehicles exceed the recommended standards, and that vibration levels exceed those that are "very uncomfortable" for healthy adults. METHODS: We measured noise and vibration (n/v) levels inside and outside a neonatal transport incubator in seven transport vehicles (land, air, and water), and calculated maximum and average, weighted and unweighted levels. RESULTS: The maximum and average unweighted noise levels in all but one vehicle were over 99 dB. The incubator amplified noise at the lower frequencies (The Canadian Standards Association 1992 recommendation is that the noise level in transport incubators not exceed 60 dBA). The maximum vibration levels ranged from 0.86 m.S-2 to 2.35 m.S-2, and the average levels ranged from 0.33 m.S-2 to 1.46 m.S-2. (Vibration in excess of 1.5 is considered "very uncomfortable," and in excess of 2.0 is "extremely uncomfortable" for healthy adults.) CONCLUSIONS: Noise and vibration levels inside transport incubators in our most-commonly used transport vehicles often exceed the recommended limits. For neurologically immature and/or physiologically compromised infants and children, current levels of n/v in transport vehicles are too high, and could affect patient morbidity. These n/v levels require further study, and modification of equipment, primarily the incubators, is overdue.

Air Ambulances↗
PubMed1994

Self-report of obsessions and worry.

The relationships between self-reported worry and obsessional-compulsive symptoms were examined among 145 hospital outpatients. Subjects completed the Penn State Worry Questionnaire and the Padua Inventory. Despite moderately strong correlations, the scales measured distinct constructs. Eliminating five items from the Padua Inventory may improve its discriminant validity. Correlations with the Padua Inventory subscales showed that obsessional loss of mental control was moderately correlated to both worry and checking, whereas worry and checking were only weakly correlated. The results are discussed in terms of possible relationships between worry and obsessions.

Adult↗
PubMed1994

Health-related intrusive thoughts.

Two studies address the prevalence, concomitants, and appraisal of health-related intrusive thoughts. Eighty-three percent of adults (N = 658) in waiting rooms of two general hospitals reported at least one intrusive thought during the preceding month and 75.0% of patients and 55.5% of people accompanying them reported a health-related intrusive thought in the same period. The intrusions were associated with anxious and depressive symptoms. Health related intrusive thoughts were reported by 61% of a sample of university students (N = 608) and were the most frequent intrusive thought among 19.9% of the students. First, triggering stimuli reported by the subjects were significant predictors of thought frequency, worry, removal difficulty, and effort used in removing the thought. Second, appraisals of high probability were significant predictors of high frequency, worry, and especially difficulty in removing the thought. Finally, perceived responsibility and disapproval of the thought were also significant predictors of thought frequency, worry, removal difficulty, effort used in removing the thought, and guilt. These data support the position that cognitive appraisal of intrusive thoughts is closely linked to the subjective experience of the thought: more extreme appraisals were associated with more troublesome thoughts. The clinical implications of these studies are discussed in terms of current models of hypochondriasis and health anxiety.

Adult↗
PubMed1994

Genes of stress in experimental hypertension.

1. A significant portion of blood pressure variance is modified by the environment. 2. The present report summarizes evidence that: (i) the environmental response is genetically determined; (ii) various stressors can evoke a differential response in hypertensive animals and constitute its intermediate phenotypes; (iii) the response to heat stress can be assigned to a single 'thermosensitivity' locus; (iv) candidate genes of susceptibility to environmental stresses are member(s) of the heat stress gene (HSP) gene families; (v) a restriction fragment length polymorphism of hsp70 and a single base mutation in the 3'-untranslated region of hsp27 are associated with hypertension in recombinant inbred strains. 3. In conclusion, HSP gene variants may be causative in susceptibility to hypertension.

Animals↗
PubMed1994

Endotoxin affinity for provisional restorative resins.

PURPOSE: This study compared the relative affinity of Porphyromonas gingivalis and Escherichia coli endotoxin, bacterial cell envelope lipopolysaccharide (LPS), for three provisional resins. MATERIALS AND METHODS: As-polymerized and pumiced polymethyl methacrylate and polyethyl methacrylate resin discs were exposed to 1,000 endotoxin U/mL P. gingivalis or E. coli LPS in water for 24 hours at 37 degrees C, whereas control discs were placed in LPS-free water. LPS-treated discs were transferred at 24-hour intervals to fresh, LPS-free water for up to 96 hours, and the incubated eluates were tested for the presence of LPS. RESULTS: Initial adherence of P. gingivalis LPS to as-polymerized and pumiced-finish resin was a function of resin type, but surface characteristics modified adherence levels. When steady rates of elution were reached at 72 to 96 hours, as-polymerized specimens released significantly greater LPS levels than pumiced samples. Comparison of initial adherence of P. gingivalis and E. coli LPS with pumiced resins showed that adherence was based on a combination of LPS and resin type. P. gingivalis LPS had a greater relative affinity for polyethyl methacrylate, and E. coli LPS has a greater relative affinity for polymethyl methacrylate. Regardless of resin type, P. gingivalis LPS eluted at levels greater than E. coli LPS. CONCLUSIONS: The affinity of LPS for provisional resins seems to be a function of selective interactions based on the chemical nature of the resin, the surface finish of the resin, and the molecular structure of the LPS.

Analysis of Variance↗
PubMed1993

Idiographic considerations in the behavioral treatment of obsessional thoughts.

Despite impressive improvement in the behavioral treatment of obsessive-compulsive disorder over the last 15 years, progress has been slower for obsessional thoughts with few or no overt rituals. Encouraging case reports suggest that exposure to obsessional thoughts combined with covert response prevention is an effective treatment. Three cases are presented that required adaptation from the guidelines laid out by Salkovskis and Westbrook (1989). They provide clear evidence of the need to adopt a creative and flexible approach to exposure that enables access and activation of fear structures.

Adult↗
PubMed1993

[A crisis intervention service in an outpatient psychiatric clinic of a general hospital: function and clientele].

The authors describe an external crisis intervention service in a general hospital. This service is intended for a clientele presenting acute mental health problems, referred, in the majority of cases, from the emergency department. They present demographic data, diagnostic data, data on the factors precipitating the crises and data which can be used to qualify and quantify the clientele. In addition, they describe the therapeutic approach and the treatment philosophy, the number of follow-up sessions, and the guidance provided to the clientele after follow-up. Finally, the authors suggest prerequisites considered essential to the effective operation of a crisis intervention module in an external psychiatric clinic.

Adolescent↗
PubMed1992

Cognitive intrusions in a non-clinical population. II. Associations with depressive, anxious, and compulsive symptoms.

The relationships between experimental dimensions of cognitive intrusions and depressive, anxious, and compulsive symptoms were studied among 125 university students. The students completed a questionnaire describing and evaluating seven cognitive intrusions and inventories of depressive, anxious, and compulsive symptoms. Principal component factor analysis on the 14 cognitive intrusion questionnaire dimensions identified five factors that were interpreted as general distress, evaluation, control, diversity and attention. Hierarchical regression analysis showed that effortful strategies in response to cognitive intrusions, general distress and diversity were predictors of both Beck Depression and Beck Anxiety Inventory scores. The evaluation factor consisting of perceived responsibility, disapproval and guilt ratings was also associated with depression and was the only significant predictor of Compulsive Activity Checklist scores. The control factor, consisting of items describing successful application of response strategies, was negatively related to BAI scores. The results are discussed as providing support for Salkovskis' formulation of obsessive-compulsive disorder.

Adult↗
PubMed1992

Electrophoretic transfer of DNA from gels to filters by using a homemade apparatus.

Electroblotting is a rapid and high-efficiency method of transferring DNA from gels to the variety of membranes available, in very short time frames when compared with capillary-blotting techniques and with much less preparation required. A simple apparatus made of two food savers, one dialysis membrane, one sponge, and two removable electrodes was used to transfer DNA molecules up to 21 kb, from agarose gels to nitrocellulose filters, in less than 30 min. A recombinant pAT153 plasmid carrying the human cytomegalovirus BamH I-P fragment (7.2 kb) was rapidly identified by hybridization, using our simplified transfer procedure.

Blotting, Southern↗
PubMed1992

Diurnal changes in the profile shape and range of motion of the back.

The diurnal height change reported to occur in young adults was investigated to characterize changes in the lumbar range of motion, spinal profile, and range of motion of the back. Twelve subjects aged 18-22 years were measured using stereophotography and standard clinical examinations in the evening and after a minimum of 8 hours of complete bed rest. The average increase in height was 20 mm. Forty percent of the height increase took place in the lumbar spine without change in the depth of the lordosis, and forty percent took place in the thoracic curve with a decrease in the kyphosis. The remaining 20% of the height increase was not located, but no measurements were taken of the cervical spine. Range of motion studies revealed that lumbar flexion, as measured using the lumbar flexion increment, was decreased in the morning, and straight leg raise was decreased when measured clinically but not when measured photographically. Extension, rotation, and femoral stretch test were not affected. The authors conclude that stereophotogrammetry offers an accurate, noninvasive way to study spinal profiles. Further work is needed to assess and quantify the relative motion of the skin and the underlying structures.

Adult↗
PubMed1992

[An assessment of international migration toward Montreal in the nineteenth century].

"This text first of all considers the quantitative aspects of this migratory phenomenon, demonstrating that it underwent a change of rhythm starting in the 1840s and that the 1850s and 1880s were the decades where the pace was strongest. The article also places this mobility with respect to Montreal's overall demographic context in the [nineteenth] century. A profile of the migrants is then reconstructed, as best enabled by the current state of research. The following themes are subsequently discussed: place of origin of the migrants, their demographic and professional characteristics, the causes for their migration and their integration into the place of arrival." (SUMMARY IN ENG AND SPA)

Acculturation↗
PubMed1991

Cognitive intrusions in a non-clinical population. I. Response style, subjective experience, and appraisal.

The present study identified distinctive response styles to unpleasant cognitive intrusions to further understanding of intrusive phenomena similar to those observed in obsessive-compulsive disorder and other anxiety disorders. Response styles were studied among 125 university students who completed a questionnaire describing and evaluating seven cognitive intrusions and inventories of depressive, anxious, and compulsive symptoms. Almost all subjects (99%) reported intrusions and 92% included effortful strategies in response to intrusions in their repertoire. Large differences were observed in the dominant strategy used. Three distinctive dominant response styles were identified including no effortful response (26%) and two effortful styles, attentive thinking (34%), and escape/avoidance (40%). The two groups using effortful strategies were more anxious and reported more difficulty removing intrusions. The group using escape/avoidance strategies reported more sadness, worry, guilt, and disapproval than subjects reporting no effortful response. The attentive thinking group reported more varied forms and more frequently triggered intrusions then the no effortful response group. Within subject analyses support the group comparisons and showed that intrusions eliciting escape/avoidance strategies were evaluated more disapprovingly than thoughts eliciting attentive thinking. The results are discussed in terms of Salkovskis' (Behavior Research and Therapy, 27, 677-682, 1985) formulation of obsessive-compulsive disorder and Borkovec's (Journal of Consulting and Clinical Psychology, 23, 481-482, 1985) and Barlow's (Anxiety and its disorders: The nature and treatment of anxiety and panic, 1988) discussions of worry and generalized anxiety.

Adaptation, Psychological↗
PubMed1991

Back pain and spinal changes in microgravity.

We believe that investigations into back pain and spinal changes in microgravity will contribute significantly to our knowledge and understanding of factors that cause back pain and the influence of spinal cord distraction on sensory and autonomic dysfunction. This information may have clinical implications for the treatment and rehabilitation of patients with spinal cord injury, for the care of patients during and after corrective spinal surgery, for the care and treatment of patients with chronic pain syndromes, and may potentially provide us with the opportunity to learn more about demyelinating diseases.

Back Pain↗