Effects of H+-K+ ATPase inhibitors (omeprazole and lansoprazole) on fertilization-induced bioelectrical potential changes in the egg of the frog, Rana cameranoi

Fertilization triggers Ca2+ increase and alkalization in the eggs of some species such as the frog. Ooplasmic Ca2+ increase triggers fertilization potential (FP), and alkalization can have a permissive effect in Ca2+ increase. It can be expected that pH regulation in the egg can affect both ooplasmic Ca2+ levels and the events triggered by increasing Ca2+. The evidence of the possibility of H +-K+ ATPase in different tissues in recent studies prompted us to wonder about the probability of the existence of this pump in the egg. Therefore, we decided to investigate the presence of H+-K + ATPase by bioelectrical potential recordings in frog eggs. Thus, frog eggs were inseminated while the resting membrane potential (RMP) in the solution containing different concentrations (0.3, 0.6, 0.9 and 1.2 mM) of pump inhibitors (omeprazole and lansoprazole) was recorded. Evidence of H +-K+ ATPase was sought from the effects of these pump inhibitors on FP variables. While omeprazole had a significant effect on RMP and FP variables at a 1.2 mM concentration alone, lansoprazole had significant effects at concentrations higher than 0.6 mM in the frog eggs. It was determined that the effects of the 2 inhibitors were similar. In conclusion, H +-K+ ATPase may be present in frog eggs due to the similar effects of both pump inhibitors on the potential change triggered by fertilization. Thus, this pump might have a function in alkalization triggered by fertilization in the frog egg

Determination of an optimal threshold value for muscle activity detection in EMG analysis

It is commonly agreed that one needs to use a threshold value in the detection of muscle activity timing in electromyographic (EMG) signal analysis. However, the algorithm for threshold determination lacks an agreement between the investigators. In this study we aimed to determine a proper threshold value in an incremental cycling exercise for accurate EMG signal analysis. Nine healthy recreationally active male subjects cycled until exhaustion. EMG recordings were performed on four low extremity muscle groups; gastrocnemius lateralis (GL), gastrocnemius medialis (GM), soleus (SOL) and vastus medialis (VM). We have analyzed our data using three different threshold levels: 25%, 35% and 45% of the mean RMS EMG value. We compared the appropriateness of these threshold values using two criteria: (1) significant correlation between the actual and estimated number of bursts and (2) proximity of the regression line of the actual and estimated number of bursts to the line of identity. It had been possible to find a significant correlation between the actual and estimated number of bursts with the 25, 35 and 45% threshold values for the GL muscle. Correlation analyses for the VM muscle had shown that the number of bursts estimated with the 35% threshold value was found to be significantly correlated with the actual number of bursts. For the GM muscle, it had been possible to predict the burst number by using either the 35% or 45% threshold value and for the SOL muscle the 25% threshold value was found as the best predictor for actual number of burst estimation. Detailed analyses of the actual and estimated number of bursts had shown that success of threshold estimation may differ among muscle groups. Evaluation of our data had clearly shown that it is important to select proper threshold values for correct EMG signal analyses. Using a single threshold value for different exercise intensities and different muscle groups may cause misleading results. © Journal of Sports Science and Medicine

Differential contributions of right and left brains to paw skill in right- and left-pawed female rats

PubMedID: 12888418Paw preference and paw frequency was studied in female rats. Paw preference was assessed using a modified version of food reaching task in quadrupedal position. Of 68 rats, 56 (82.4%) were right-handed, 7 (10.3%) were left-handed, and 5 (7.4%) were mixed-handed. There were significantly more right-handers than left-handers. The distribution of right ® minus left (L) paw reach (R + L = 50) was not U-shaped, it was J-shaped like in humans. Estrus cycle was a significant factor influencing the right-paw entry scores: most of left-handers were in estrus and proestrus, most of left-handers were in estrus, and most of mixed-handers were in postestrus. In right- and non-right-handers, the frequency of right-paw usage (right-hand skill) increased linearly with testing days, but the frequency of left-hand usage (left-hand skill) did not show significant changes with the successive testing days. Controlling for body weight and estrus only accentuated these results. It was concluded that distribution of hand preference in rats is J-shaped and there is a right-sided population bias in handedness in rats like in humans. The results suggested that motor learning in paw skill is mainly involved the left brain in right- and mixed-handed rats, not the right brain: only the left brain has the inbuilt capacity for motor learning in female rats. Such an asymmetric cognitive control in an animal model may have a major impact in many aspects of biology in respect to normal functioning, superior talents, and disease (see Geschwind, 1985)

A comparison of the maximal fat oxidation rates of three different time periods in the Fatmax stage

PubMedID: 30787650This study aimed to compare the maximal fat oxidation (MFO) rates obtained from the stage average, last 2 min average, and highest value in the Fatmax stage determined with a 6 min step protocol. A total of 35 overweight, sedentary healthy men (age: 25.4 ± 0.7 years, body mass index: 26.0 ± 0.6 kg/m 2 ) participated in the study. Substrate oxidation was calculated using breath-bybreath gas exchange data for each stage. When the change in the fat oxidation rate for every min throughout the Fatmax stage was evaluated, the average value of the 4th min was significantly lower than that of the 2 nd and 3 rd min (p < 0.01). In addition, the 5th and 6th min fat oxidation rates were significantly lower than the rates of the 1 st , 2 nd , 3 rd , and 4th min (0.30 ± 0.01 and 0.29 ± 0.01 g/min for the 5 th and 6 th min, respectively, vs. 0.35 ± 0.02, 0.34 ± 0.02, 0.33 ± 0.02, and 0.31 ± 0.01 g/min for the 1 st , 2 nd , 3 rd , and 4 th min, respectively; p < 0.01). Most of the participants had MFO rates in the 1 st min of the stage (16/35 participants), and the MFO rates of the remaining participants were observed in the 2 nd , 3 rd , and 4 th min (7/35, 4/35, and 8/35 participants, respectively). None of the participants had MFO rates in the 5 th or 6 th min. The individual MFO rate (highest fat oxidation rate during Fatmax) was significantly higher than the fat oxidation rate calculated with the last 2 min average values (0.36 ± 0.02 and 0.30 ± 0.01 g/min, respectively; p < 0.05). In conclusion, the calculation of the fat oxidation rate by averaging the last portion of the Fatmax stage data may cause the underestimation of the MFO rate, which probably occurs earlier in the Fatmax stage. © Journal of Sports Science and Medicine

Effect of hot environmental conditions on physical activity patterns and temperature response of football players

PubMedID: 21029201Heat stress may contribute to decreased match performance when football is played in extreme heat. This study evaluated activity patterns and thermal responses of players during soccer matches played in different environmental conditions. Non-acclimatized soccer players (n=11, 20±2 years) played two matches in conditions of moderate heat (MH) and high heat (HH) index. Core temperature (Tc) and physical performance were measured using a telemetric sensor and a global positioning system, respectively. The average ambient temperature and relative humidity were MH 34±1 °C and 38±2%; HH 36±0 °C and 61±1%. Peak Tc in the MH match was 39.1±0.4 °C and in the HH match it was 39.6±0.3 °C. The total distance covered in the first and second halves was 4386±367 and 4227±292 m for the MH match and 4301±487 and 3761±358 m for the HH match. Players covered more distance (P<0.001) in the first half of the HH match than in the second half. In football matches played at high environmental temperature and humidity, the physical performance of the players may decrease due to high thermal stress. © 2010 John Wiley & Sons A/S