1,720,968 research outputs found
The characterization of thermal perception in recreational surfers wearing wetsuits
No full textThe purpose of this study was to characterize the perception of heat loss, comfort, and wetness in recreational surfers wearing wetsuits, to compare these data with changes in skin temperature reported in prior studies, and to examine the impact of wetsuit thickness, zipper location, and accessory use on thermal sensation and comfort. Following their surf session, nine-hundred and three male (n = 735) and female (n = 168) recreational surfers responded to a series of questions regarding thermal comfort/sensation, wetsuit characteristics, and surfing history. Average whole body thermal sensation rating was 0.8 ± 3.6 on a scale of -10 to +10 and average whole body thermal comfort rating was 1.5 ± 1.2, midway between "just comfortable" and "comfortable." Overall, surfers felt coldest in their feet, hands, and head. Under their wetsuits, surfers felt the coldest, wettest, and least comfortable in their chest, lower legs, lower arms, and upper back. Wetsuit accessory use had the greatest impact on regions identified as coldest, least comfortable, and wettest. These data suggest that wetsuit design should focus on optimizing water access points and improving accessories for the feet, hands, and head.</p
Impact of excess gestational and post-weaning energy intake on femoral artery vascular function of swine offspring
No full textThe genesis of disease development can be linked to the intrauterine environment, and gestational nutrition is known to play a significant role in the future vascular health of the offspring. The aim of this examination was to determine the impact of excessive gestational and post-weaning energy intake on offspring vascular function and gene expression associated with the nitric oxide (NO) pathway. Duroc x Landrace gilts (n=16) were assigned to either a high energy (HE) providing 10,144 Kcal/day (n=8) or normal energy (NE) providing 6721 Kcal/day (n = 8) diet throughout pregnancy. Male and female piglets from each sow were randomly assigned within sex to receive either a HE diet or NE diet. At 3 months of age the femoral artery was harvested from male and female offspring, representing each group of maternal and postnatal diet (n=47). Endothelial-dependent and -independent vasorelaxation were measured using wire-myography and increasing concentration of bradykinin (BK) and sodium nitroprusside (SNP), respectively. Quantitative real time-polymerase chain reaction was used to analyze the expression of eNOS, GUCY1A3, and GUCY1B3. Both BK and SNP induced vasorelaxation were significantly reduced in the femoral arteries of gestational HE offspring compared to gestational NE offspring. However, there was no effect for the post-weaning diet on BK and SNP induced vasorelaxation. No significant differences were observed in the gene expression of either eNOS or GUCY1A3 between the offspring. In conclusion, these findings suggest that a HE gestational diet can play a critical role in the development of offspring vascular function, predisposing them to vascular dysfunction. This dysfunction may lead to atherosclerotic disease development later in life. Furthermore, these results suggest that the reduced endothelium-dependent and -independent vasorelaxation responses were not due to gene expression differences of eNOS or GUCY1A3
Influence of gene expression on the development and progression of atherosclerosis
No full textThis investigation aimed to compare gene expression differences between atheroresistant (brachial) and atherosusceptible (femoral) arteries in 13day old Rapacz HC swine, as well as identify gene expression associated with the initiation and progression of peripheral atherosclerosis in the same arteries of one and two year old Rapacz HC swine. Methods: A paired t-test was used to compare gene expression of healthy brachial and femoral arteries in the 13day old Rapacz HC swine. A 2x2 ANOVA was used to analyze the arteries from one and two year old Rapacz HC swine. Disease phenotype was quantified using Sudan IV, H/E, and VVG staining. Hypotheses: We hypothesized that gene expression differences between healthy brachial and femoral arteries in the 13day old Rapacz HC swine will contribute to the uneven atherosclerotic disease distribution later in the animal’s life. In addition, we hypothesized that gene expression differences will diverge in one and two year old animals due to an increase in disease in the femoral but no lesion formation in the brachial artery. Results: Healthy arteries from the 13day old Rapacz HC swine showed a total of 366 significantly different expressed probe sets between the atheroprotected and atherosusceptible artery. Analysis of these probe sets is the first evidence that gene expression differences could contribute to the uneven disease distribution later in life. A total of 184 probe sets were identified by the ANOVA as having a significant age*artery interaction. In addition BLAST identified that these probe sets are very similar to genes involved in known atherogenic pathways. Interestingly, contrary to our hypothesis the number of differently expressed genes decreased with increasing disease in the femoral artery
Peripheral arterial disease in spinal cord injury
No full textSpinal cord injury leads to a variety of sequelae that are determinental to the health of the individual incurring the injury including reduced physical activity, altered body composition, metabolic abnormalities, and increased cardiovascular disease risk. Arterial structure, function, and hemodynamics below the neurological injury level also are altered within weeks of the injury providing evidence that spinal cord injured individuals (SCI) may be predisposed to higher rates of lower-extremity peripheral arterial disease (PAD) compared to able-bodied controls. The purpose of this study was to investigate whether SCI have greater rates of PAD compared to controls and further to determine whether individuals meeting current physical activity recommendations have less PAD. Additionally, we sought to determine whether hemodynamics were altered and to investigate whether altered hemodynamics were associated with measures of PAD. We hypothesized that SCI would have greater rates of PAD, exercise would improve these measures, hemodynamics would be altered in SCI and would be related to PAD measures. To test these hypotheses we utilized an ankle brachial index (ABI) and vascular ultrasonography to determine intima media thickness (IMT) as well as hemodynamic environment in four arteries including the brachial (BA), carotid (CA), superficial femoral (SFA), and popliteal (PA). An ABI and ultrasonography was performed in 105 SCI and 156 able-bodied controls with groups further sub-divided into physically active and sedentary. ABIs were significantly lower in SCI versus controls (0.96 ± 0.12 vs. 1.06 ± 0.07, p \u3c 0.001). Physical activity grouping demonstrated a trend for larger ABI in active compared to sedentary controls (1.08 ± 0.07 vs. 1.05 ± 0.07, p = 0.06), whereas no differences were seen in ABI measurements for active versus sedentary SCI (0.94 ± 0.11 vs. 0.97 ± 0.10, p = 0.28). Upper-body BA and CA IMTs were similar in controls versus SCI. Lower extremity IMTs revealed similar thicknesses for both SFA and PA, but when normalized for artery diameter, individuals with SCI had greater IMT than controls in the SFA (0.094 ± 0.03 vs. 0.073 ± 0.02 mm/mm lumen diameter, p \u3c 0.01) and PA (0.117 ± 0.04 vs. 0.091 ± 0.02 mm/mm lumen diameter, p \u3c 0.01). Lower-extremity artery hemodynamics were altered in SCI in a direction of atheroprotection including increased resting mean shear and reduced resting oscillatory shear index (OSI). OSI was lower in SCI compared to controls for SFA (0.16 ± 0.009 vs. 0.26 ± 0.005, p \u3c 0.01) and PA (0.20 ± 0.011 vs. 0.26 ± 0.004, p \u3c 0.01). Mean shear rate was higher in SCI compared to controls for SFA (43.54 ± 2.79 vs. 20.48 ± 1.09 s-1, p \u3c 0.01) and PA (30.43 ± 2.79 vs. 11.68 ± 0.79 s-1 , p \u3c 0.01). The evidence of a greater burden of PAD in the lower-extremities of SCI should prompt physicians providing care for these individuals to utilize these methods to screen for PAD
The effect of upright posture on lower extremity endothelial cell function
No full textHumans spend the majority of their day in an upright posture thus exposing their lower extremity vasculatures to acute bouts of elevated pressures. This increased pressure in the legs may be a contributing factor to endothelial cell dysfunction and atherosclerosis. The hypothesis that increases in pressures leads to endothelium dysfunction was tested in the popliteal artery during a 3-hour upright intervention protocol. Popliteal artery flow-mediated dilation (FMD) was assessed prior to and post a 3-hour intervention encompassing either sitting (intervention day) or laying down (control day). Contrary to the hypothesis, the upright sitting did not have an impact on popliteal artery endothelial cell function (P \u3e 0.05). This is in disagreement with previous research showing that a 3-hour increase in pressure in the brachial artery negatively impacts endothelial cell function [1]. It is possible that a 3-hour intervention was not sufficient time to elicit any change to endothelial cell function given that the popliteal artery is exposed to this hydrostatic challenge daily in this subject population. In conjunction, adaptation may have already occurred in this vasculature sparing it from decreases in endothelial cell function following bouts of high blood pressure
No impact of maternal exercise during pregnancy on rat offspring physical activity and food consumption
No full textBoth the prenatal environment and postnatal behaviors have been shown to influence the long term health of an individual. The prenatal environment has an even greater lasting effect on the offspring\u27s health once outside the womb by programming postnatal behaviors. To date, factors such as undernutrition, overnutrition and stress have been shown to influence the offspring\u27s postnatal behaviors in a detrimental manner. A preliminary study performed using offspring from either exercise trained or sedentary crossbred swine trended towards having positive postnatal behavioral effects such as decreased food consumption and increased physical activity levels in offspring from the trained group. Therefore, an investigation using a more stringent protocol in a rat model was performed to determine the effects of maternal exercise during pregnancy on an offspring\u27s postnatal activity and food consumption. Nineteen pregnant female Sprague Dawley rats were randomly divided into EX (n=9) or a SED (n=10) groups. The EX dams were allowed voluntary access to freely rotating running wheels, whereas SED dams had access to locked running wheels throughout pregnancy. At weaning, two male (M) and two female (F) offspring from each dam were placed on either a high fat (HF) or normal (N) diet. Wheel running (WR) and food consumption (FC) were measured over a two day period in the offspring at 2, 4, 6, and 8 months of age. Twenty-four hour WR distance was assessed in offspring using a running wheel that was housed within the cage. FC was calculated as a difference in food weight over a 24 hours period and expressed as kilocalories consumed. Neither WR nor FC behavior was significantly different between the offspring from either EX or SED dams at 2, 4, 6, or 8 months of age. In conclusion, these results suggest that maternal exercise during pregnancy does not significantly alter the physical activity or food consumption behaviors of rat offspring throughout their lifespan
Acute impact of intermittent pneumatic leg compression frequency on limb hemodynamics and vascular function in humans
No full textIntermittent pneumatic leg compression (IPC) therapy is commonly used to treat symptoms associated with peripheral artery disease. However, the physiologic mechanism responsible for its effectiveness remains speculative. One hypothesis is that IPC increases shear stress during treatment and enhances endothelial cell (EC) function. In order to test this hypothesis we 1) characterized the hemodynamic profile in the treatment limb during IPC application and 2) used flow mediated dilation (FMD) and peak reactive hyperemia blood flow (RHBF) to assess alterations in EC function in response to single session of IPC. Eleven male subjects (age: 23.5 ± 4.7 years) underwent an hour of HF (2s inflation/3s deflation) and LF (4s inflation/16s deflation) IPC treatment on separate days. Doppler/ultrasonography of the popliteal artery was used to measure blood velocity and diameter at the 5th and 45th minute of treatment. FMD and RHBF were assessed pre and post treatment. IPC treatment had no effect on popliteal FMD (HF: pre: 2.45±.50%, post: 2.76 ±.32%; LF: pre: 3.16±.36%, post: 3.56±.52%) or RHBF. Cuff deflation elevated blood flow (BF) and shear rate (SR) and decreased oscillatory shear index (OSI) from baseline at the onset of both treatments (p\u3c.01). This effect was lost by the 45th minute of HF treatment. When compared to baseline, both treatments significantly reduced BF and SR and increased OSI during cuff inflation (p\u3c.01). In conclusion, a single session of IPC does not acutely impact popliteal FMD or RHBF despite significant alterations to the hemodynamic profile during treatment
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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