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Biomedical subjects

C Gascon

Publications and source records attributed to C Gascon.

6 recordsLinked to original sources
PubMed2001

Relative contribution of mental health and exercise-related pain increment to treadmill test intolerance in patients with chronic low back pain.

STUDY DESIGN: A cross-sectional study. OBJECTIVES: To determine the relative contribution of pain increase and mental health to testing performance during a single bout of exercise in patients with chronic low back pain. BACKGROUND: Controversy exists as to which factors principally limit physical performance in patients with chronic low back pain. Some believe psychological factors limit physical performance, whereas others believe activity-related increases in pain intensity limit performance. METHODS: Seventy-five patients with chronic low back pain reported pain intensity before and after undergoing a maximal, symptom-limited modified treadmill test. Walking time (in minutes) and aerobic fitness were measured. The Short Form 36 Health Survey was administered to all patients. RESULTS: Fifty-four percent of the sample stopped testing because of a significant increase in pain intensity (P = 0.0001). Treadmill performance was lower in patients who stopped because of pain than in those who stopped because of fatigue (P = 0.02). The patients who stopped because of pain were also more likely to have low mental health as assessed by the Short Form 36 Health Survey. Low mental health, however, did not have a statistically significant influence on treadmill performance. CONCLUSION: The data indicate that impairment of physical performance during treadmill testing in patients with chronic low back pain is attributable to testing-induced increase in pain intensity rather than to individual low mental health scores.

Adult↗
PubMed2000

Riverine barriers and the geographic distribution of Amazonian species.

Rivers have been suggested to have played an important role in shaping present-day patterns of ecological and genetic variation among Amazonian species and communities. Recent molecular studies have provided mixed support for the hypothesis that large lowland Amazonian rivers have functioned as significant impediments to gene flow among populations of neotropical species. To date, no study has systematically evaluated the impact that riverine barriers might have on structuring whole Amazonian communities. Our analyses of the phylogeography of frogs and small mammals indicate that a putative riverine barrier (the Juruá River) does not relate to present-day patterns of community similarity and species richness. Rather, our results imply a significant impact of the Andean orogenic axis and associated thrust-and-fold lowland dynamics in shaping patterns of biotic diversity along the Juruá. Combined results of this and other studies significantly weaken the postulated role of rivers as major drivers of Amazonian diversification.

Animals↗
PubMed1999

Ridges and rivers: a test of competing hypotheses of Amazonian diversification using a dart-poison frog (Epipedobates femoralis).

Mitochondrial DNA cytochrome b sequence data from a dart-poison frog, Epipedobates femoralis, were used to test two hypotheses of Amazonian diversification: the riverine barrier and the ridge hypotheses. Samples were derived from sites located on both banks of the Rio Juruá and on both sides of the Iquitos Arch in western Amazonia. The phylogeographic structure was inconsistent with predictions of the riverine barrier hypothesis. Haplotypes from opposite river banks did not form monophyletic clades in any of our phylogenetic analyses, nor was the topology within major clades consistent with the riverine hypothesis. Further, the greatest differentiation between paired sites on opposite banks was not at the river mouth where the strongest barrier to gene flow was predicted to occur. The results instead were consistent with the hypothesis that ancient ridges (arches), no longer evident on the landscape, have shaped the phylogeographic relationships of Amazonian taxa. Two robustly supported clades map onto opposite sides of the Iquitos Arch. The mean haplotypic divergence between the two clades, in excess of 12%, suggests that this cladogenic event dates to between five and 15 million years ago. These estimates span a period of major orogenesis in western South America and presumably the formation of these ancient ridges.

Animals↗