Examination of the role of transient receptor potential vanilloid type 4 in endothelial responses to shear forces

Shear stress is the major mechanical force applied on vascular endothelial cells by blood flow, and is a crucial factor in normal vascular physiology and in the development of some vascular pathologies. The exact mechanisms of cellular mechano-transduction in mammalian cells and tissues have not yet been elucidated, but it is known that mechanically sensitive receptors and ion channels play a crucial role. This paper describes the use of a novel and efficient microfluidic device to study mechanically-sensitive receptors and ion channels in vitro, which has three independent channels from which recordings can be made and has a small surface area such that fewer cells are required than for conventional flow chambers. The contoured channels of the device enabled examination of a range of shear stresses in one field of view, which is not possible with parallel plate flow chambers and other previously used devices, where one level of flow-induced shear stress is produced per fixed flow-rate. We exposed bovine aortic endothelial cells to different levels of shear stress, and measured the resulting change in intracellular calcium levels ([Ca²⁺]_i) using the fluorescent calcium sensitive dye Fluo-4AM. Shear stress caused an elevation of [Ca²⁺]_i that was proportional to the level of shear experienced. The response was temperature dependant such that at lower temperatures more shear stress was required to elicit a given level of calcium signal and the magnitude of influx was reduced. We demonstrated that shear stress-induced elevations in [Ca²⁺]_i are largely due to calcium influx through the transient receptor potential vanilloid type 4 ion channel.     

Research Study on an Applied Interdisciplinary Product Development Course for College Sophomores

This research compares the industry readiness, product development skill level, and overall knowledge gains of students taking an undergraduate research course (treatment) to those who did not (control). This 2‐semester Applied Interdisciplinary Product Development (AIPD) course for sophomores brought together interdisciplinary teams of food science, nutrition, and packaging science students in a hands‐on setting to create healthy food products for children, complete with retail packaging. A Subject Knowledge Assessment (SKA) was used to evaluate the mean percent difference value (MPDV) of food science, nutrition, packaging science, and general product development knowledge gained through the course. SKA results indicated that the MPDV were significantly different (α = 0.05) between the treatment and comparison groups in the overall score and in every subject area score except packaging science. Data from an Exit Questionnaire (EQ) was used for evaluation of attitudes pertaining to product development knowledge and skills, department engagement, and pedagogy. EQ results indicated that mean scores between the treatment and comparison groups were significantly different (α = 0.05) in 7 of the 9 statements on product development knowledge and skills, both statements pertaining to pedagogy, and the statement pertaining to department engagement. Overall, the research project was considered a successful intervention for educating sophomores at the University. Overall, the research project was considered a successful intervention for educating sophomores in the Food, Nutrition and Packaging Science department at Clemson University. The student‐lead teams were held to a greater degree of accountability for their success in terms of education gleaned and value of experience gained as metric for the University and other IFT Accredited programs.     

Specificity of a Maximal Step Exercise Test

To adhere to the principle of “exercise specificity” exercise testing should be completed using the same physical activity that is performed during exercise training. The present study was designed to assess whether aerobic step exercisers have a greater maximal oxygen consumption (max VO₂) when tested using an activity specific, maximal step exercise test (SET; arms and legs) versus a maximal running test (legs only). Female aerobic step exercisers (N=18; 20.7 ± 1.5 years) performed three maximal graded exercise tests (GXTs): 2 SETs; 1 treadmill test (TMT). The SET consisted of six 3-min progressive stages of alternate lead, basic step, basic step with biceps curls, knee raise with pull-down, repeater knee with pull-down, lateral lunge with pull-down, and side squat with shoulder presses. Stepping rate was 32 steps· min^?1 on an 8-in (20.32 cm) step for stages 1–3, and a 10-in (25.4 cm) step for stages 4–6. Submaximal and maximal heart rate (HR) and oxygen consumption (VO₂) were recorded at the end of each stage. Test–retest reliability for the first five stages of the SET ranged from .91 to .97 for HR, and from .84 to .96 for VO₂. Maximal HR was significantly greater (p =.0001) for the SET (200 ± 6.2 beats·min^?1) as compared to the TMT (193 ± 7.9 beats·min^?1). No significant difference was found for max VO₂ (42.9 ± 8.5, 41.2 ± 5.9 ml·kg^?1·min^?1, p =.14). The SET was a valid and reliable protocol for assessing responses of these aerobic step exercisers; however, max VO₂ from a TMT did not differ significantly from the SET. Conversely, max HR obtained from the criterion TMT was 7 beats·min^?1 lower than from the SET. If a training HR for step exercise (arms and legs exercise) is prescribed based on the max HR from treadmill exercise (legs only), then the training HR should be calculated from a TMT max HR that has been increased by 7 beats·min^?1 to obtain an intensity of step exercise comparable to that of running.     

Does Dampened Physiological Reactivity Protect Youth in Aggressive Family Environments?

Is an attenuated physiological response to family conflict, seen in some youth exposed to early adversity, protective or problematic? A longitudinal study including 54 youth (average age 15.2 years) found that those with higher cumulative family aggression exposure showed lower cortisol output during a laboratory‐based conflict discussion with their parents, and were less likely to show the normative pattern of increased cortisol reactivity to a discussion they rated as more conflictual. Family aggression interacted with cortisol reactivity in predicting youth adjustment: Adolescents from more aggressive homes who were also more reactive to the discussion reported more posttraumatic stress symptoms and more antisocial behavior. These results suggest that attenuated reactivity may protect youth from the negative consequences associated with aggressive family environments.