Superior oxygen and glucose supply in perfusion cell cultures compared to static cell cultures demonstrated by simulations using the finite element method

Oxygen and glucose supply is one of the important factors for the growth and viability of the cells in cultivation of tissues, e.g., spheroid, multilayered cells, and three-dimensional tissue construct. In this study, we used finite element methods to simulate the flow profile as well as oxygen and glucose supply to the multilayered cells in a microwell array chip for static and perfusion cultures. The simulation results indicated that oxygen supply is more crucial than glucose supply in both static and perfusion cultures, and that the oxygen supply through the wall of the perfusion culture chip is important in perfusion cultures. Glucose concentrations decline with time in static cultures, whereas they can be maintained at a constant level over time in perfusion cultures. The simulation of perfusion cultures indicated that the important parameters for glucose supply are the flow rate of the perfusion medium and the length of the cell culture chamber. In a perfusion culture chip made of oxygen-permeable materials, e.g., polydimethylsiloxane, oxygen is hardly supplied via the perfusion medium, but mainly supplied through the walls of the perfusion culture chip. The simulation of perfusion cultures indicated that the important parameters for oxygen supply are the thickness of the flow channel and the oxygen permeability of the walls of the channel, i.e., the type of material and the thickness of the wall.     

Scaffold fabrication in a perfusion culture microchamber array chip by O(2) plasma bonding of poly(dimethylsiloxane) protected by a physical mask

Extracellular matrix (ECM) proteins are required for cell culture. In this paper, we report the use of O(2) plasma bonding to fabricate a perfusion culture microchamber array chip with identical-size ECM spots in the isolated microchambers. The chip was fabricated by assembly of two poly(dimethylsiloxane) (PDMS) layers, a microfluidic network layer, and an ECM array layer, which were aligned and then bonded by O(2) plasma oxidation with protection of the ECM microarray with a physical mask made from PDMS. We successfully cultivated Chinese hamster ovary K1 cells in the microchambers with fibronectin. In the fibronectin microchambers, the cells adhered and extended after 12 h of static culture and then grew over the course of 1 d of perfusion culture.     

Amplitude-modulated sinusoidal microchannels for observing adaptability in C. elegans locomotion

In this paper, we present a movement-based assay to observe adaptability in Caenorhabditis elegans locomotion behavior. The assay comprises a series of sinusoidal microchannels with a fixed wavelength and modulating (increasing or decreasing) amplitude. The channel width is comparable to the body diameter of the organism. Worms are allowed to enter the channel from the input port and migrate toward the output port. Within channel sections that closely match the worm's natural undulations, the worm movement is relatively quick and steady. As the channel amplitude increases or decreases along the device, the worm faces difficulty in generating the propulsive thrust, begins to slow down and eventually fails to move forward. A set of locomotion parameters (i.e., average forward velocity, number and duration of stops, range of contact angle, and cut-off region) is defined for worm locomotion in modulated sinusoidal channels and extracted from the recorded videos. The device is tested on wild-type C. elegans (N2) and two mutants (lev-8 and unc-38). We anticipate this passive, movement-based assay can be used to screen nematodes showing difference in locomotion phenotype.     

Muscle metabolism and performance improvement after two training programmes of sprint running differing in rest interval duration

Repeated-sprint training often involves short sprints separated by inadequate recovery intervals. The effects of interval duration on metabolic and performance parameters are unclear. We compared the effects of two training programmes, differing in rest interval duration, on muscle (vastus lateralis) metabolism and sprint performance. Sixteen men trained three times a week for 8 weeks, each training session comprising 2-3 sets of two 80-m sprints. Sprints were separated by 10 s (n = 8) or 1 min (n = 8). Both training programmes improved performance in the 100-, 200-, and 300-m sprints, but the improvement was greater in the 10-s group during the final 100 m of the 200- and 300-m runs. Independent of interval duration, training mitigated the drop of muscle ATP after two 80-m sprints. The drop in phosphocreatine and the increases in glucose-6-phosphate and fructose-6-phosphate after two 80-m sprints were greater in the 10-s group. In conclusion, training with a limited number of repeated short sprints (≤10 s) may be more effective in improving speed maintenance in 200- and 300-m runs when performed with a 1:1 rather than a 1:6 exercise-to-rest ratio. This may be due to a greater activation of glycolysis caused, in part, by the limited resynthesis of phosphocreatine during the very short rest interval.     

Effect of post-match cold-water immersion on subsequent match running performance in junior soccer players during tournament play

In this study, we investigated the effects of two hydrotherapy interventions on match running performance and perceptual measures of fatigue and recovery during a 4-day soccer tournament. Twenty male junior soccer players were assigned to one of two treatment groups and undertook either cold-water immersion (5 × 1 min at 10 °C) or thermoneutral water immersion (5 × 1 min at 34 °C) after each match. High-intensity running distance (>15 km · h?1) and total distance covered, time spent in low (<80% maximum heart rate), moderate (80-90% maximum heart rate), and high (>90% maximum heart rate) heart rate zones, and rating of perceived exertion (RPE) were recorded for each match. Perceptions of general fatigue and leg soreness were recorded approximately 22 h after each match. There were decreases in both groups across the 4-day tournament for high-intensity running distance (P = 0.006, Cohen's d = 0.63), total distance run (P < 0.001, d = 0.90), time in high heart rate zone (P = 0.003, d = 0.90), and match RPE (P = 0.012, d = 0.52). Cold-water immersion was more effective than thermoneutral immersion for reducing the perception of leg soreness (P = 0.004, d = -0.92) and general fatigue (P = 0.007, d = -0.91), ameliorating the decrement in total distance run (P = 0.001, d = 0.55), and maintaining time in the moderate heart rate zone (P = 0.01, d = 1.06). In conclusion, cold-water immersion mediates the perceptions of fatigue and recovery and enhances the restoration of some match-related performance measures during a 4-day tournament.     

Intravascular haemolysis during prolonged running on asphalt and natural grass in long and middle distance runners

Surface features such as uneven playing surfaces, low impact absorption capacity and inappropriate friction/traction characteristics are connected with injury prevalence whereas force impact during foot strike has been suggested to be an important mechanism of intravascular haemolysis during running. We aimed to evaluate intravascular haemolysis during running and compare the effect of running on two different types of surfaces on haemolysis. We selected two surfaces (asphalt and grass) on which these athletes usually run. Participants were randomly assigned to group A (asphalt) or group B (grass) with 10 athletes in each group. Each athlete completed one hour of running at the calculated target heart rate (60-70%). Venous blood samples were collected before and immediately after running. We measured unconjugated bilirubin (UBR) (mg · dl(-1)), lactate dehydrogenase (LDH) (μ · ml(-1)), haemoglobin (g · l(-1)) and serum ferritin (ng · ml(-1)) as indicators of haemolysis. Athletes who ran on grass demonstrated an increase in the haematological parameters (UBR: P < 0.01, LDH: P < 0.05) when compared to athletes who ran on asphalt (UBR: P < 0.05, LDH: P = 0.241). Our findings indicate that intravascular haemolysis occurs significantly after prolonged running. Furthermore, we conclude that uneven grass surface results in greater haemolysis compared to asphalt road.     

Concurrent validity of the Polar s3 Stride Sensor for measuring walking stride velocity

With this research, we sought to establish the accuracy of stride velocity data collected by the s3 Stride Sensor Participants walked along a GAITRite mat at self-selected slow, preferred, and fast velocities, with two s3 Stride Sensors attached to their right foot. The start position was systematically varied such that the GAITRite system would record the second through sixth strides at each walking velocity. Both slow and preferred walking velocities were underestimated by 14% relative to the GAITRite (p < .05), while independent of walking velocity, Strides 2 and 3 were underestimated by 26% and 9% (p < .05), respectively. Researchers should use caution when interpreting data collected at slow and preferred walking velocities and during the first three strides.     

Quadriceps muscle blood flow and oxygen availability during repetitive bouts of isometric exercise in simulated sailing

In this study, we wished to determine whether the observed reduction in quadriceps muscle oxygen availability, reported during repetitive bouts of isometric exercise in simulated sailing efforts (i.e. hiking), is because of restricted muscle blood flow. Six national-squad Laser sailors initially performed three successive 3-min hiking bouts followed by three successive 3-min cycling tests sustained at constant intensities reproducing the cardiac output recorded during each of the three hiking bouts. The blood flow index (BFI) was determined from assessment of the vastus lateralis using near-infrared spectroscopy in association with the light-absorbing tracer indocyanine green dye, while cardiac output was determined from impedance cardiography. At equivalent cardiac outputs (ranging from 10.3±0.5 to 14.8±0.86 L · min(-1)), the increase from baseline in vastus lateralis BFI across the three hiking bouts (from 1.1±0.2 to 3.1±0.6 nM · s(-1)) was lower (P = 0.036) than that seen during the three cycling bouts (from 1.1±0.2 to 7.2±1.4 nM · s(-1)) (Cohen's d: 3.80 nM · s(-1)), whereas the increase from baseline in deoxygenated haemoglobin (by ～17.0±2.9 μM) (an index of tissue oxygen extraction) was greater (P = 0.006) during hiking than cycling (by ～5.3±2.7 μM) (Cohen's d: 4.17 μM). The results suggest that reduced vastus lateralis muscle oxygen availability during hiking arises from restricted muscle blood flow in the isometrically acting quadriceps muscles.     

Emotional support and adjustment over a year's time following sexual abuse discovery

OBJECTIVE: This study investigated age and gender differences in perceived emotional support in children and adolescents who experienced sexual abuse from the time of discovery to 1 year later. Also examined were the relations among sources of support and adjustment and whether support explained resilience, defined as better adjustment over a year's time. METHOD: One hundred and forty-seven sexually abused youth were interviewed at the time of discovery (T1) and 1 year later (T2). Information gathered included severity of the sexual abuse, satisfaction with support from caregivers, same-sex and other-sex friends, feelings of shame about the abuse, and attributional style. Youth adjustment was measured using reports from the youth themselves, caregivers, and teachers. RESULTS: Children reported the most satisfaction with support from caregivers followed by friends whereas adolescents reported similar levels of support from friends and caregivers. Satisfaction with support was differentially related to adjustment. Youth who reported more satisfaction with caregiver support at T1, reported less depression, better self-esteem but more sexual anxiety 1 year later. More satisfaction with support from friends predicted lower self-esteem but less sexual anxiety. More satisfaction with initial caregiver support at T1 predicted better parent- and teacher-rated adjustment 1 year later, after controlling for initial adjustment. CONCLUSIONS: In general, initial caregiver emotional support at the time of abuse discovery predicted resilience in child and adolescent victims of sexual abuse. Findings suggested that treatment should include a focus on helping caregivers provide appropriate emotional support.