Effects of short- and long-term changes in spatial density on the social behavior of captive chimpanzees (Pan troglodytes)

The constraints of captivity may often require non-human primates to experience restrictions in space for both long- and short-term periods of time. The tension-reduction model predicts that great apes should increase affiliative behaviors and decrease aggressive behaviors as a coping strategy. The conflict avoidance model, however, predicts that great apes should decrease all social interactions (affiliative and aggressive) as a coping strategy. The purpose of this study was to test the conflict-avoidance and tension-reduction models by examining the effects of both short-term (1–2 days) and long-term (6 months) changes in spatial density on social behavior in 23 adult captive chimpanzees (6 males, 17 females) housed at the Primate Foundation of Arizona. Affiliative (i.e., social groom, social play) and agonistic (i.e., charging display, attack) were assessed using scan-sampling techniques while subjects were rotated from high-density to low-density conditions for varying lengths of time. Results of short-term increases in spatial density (crowding) supported the conflict-avoidance strategy for females, through reduced levels of aggressive (F_1,16 = 17.11, p = 0.001) and affiliative (F_1,16 = 21.13, p < 0.001) behaviors. Males, however, supported the tension-reduction model during short-term high-density by decreasing aggression (F_1,5 = 10.53, p = 0.02) while increasing affiliation (F_1,5 = 9.10, p = 0.03). Females partially supported the tension-reduction model during long-term high-density by increasing affiliative behaviors (F_1,16 = 14.19, p = 0.002) compared to short-term high-density levels, while rates of aggression remained low. Finally, males supported the tension-reduction by reducing aggression (F_1,5 = 7.668, p = 0.04) and increasing affiliation (F_1,5 = 6.08, p = 0.05) during long-term high-density. Results confirm that chimpanzees use different strategies during short-term versus long-term increases in spatial density and that these strategies may be influenced by individual sex. However, sample sizes are small and additional research on male chimpanzees is needed.     

Postprandial profiles of CCK after high fat and high carbohydrate meals and the relationship to satiety in humans

ContextCCK is understood to play a major role in appetite regulation. Difficulties in measuring CCK have limited the potential to assess its profile in relation to food-induced satiety. Improvements in methodology and progress in theoretical understanding of satiety/satiation make it timely for this to be revisited.ObjectiveFirst, examine how physiologically relevant postprandial CCK8/33(s) profiles are influenced by fat (HF) or carbohydrate (HCHO) meals. Second, to examine relationships between postprandial CCK and profiles of satiety (hunger/fullness) and satiation (meal size).Participants and designSixteen overweight/obese adults (11 females/5 males) participated in a randomised-crossover study (46 years, 29.8 kg/m²) in a university research centre. Plasma was collected preprandially and for 180 min postprandially. Simultaneously, ratings of hunger/fullness were tracked for 180 min before an ad libitum lunch was provided.ResultsCCK8/33(s) levels increased more rapidly and reached a higher peak following HF compared to HCHO breakfast (F_(1,15) = 14.737, p < 0.01). Profiles of hunger/fullness did not differ between conditions (F_(1,15) = 0.505, p = 0.488; F_(1,15) = 2.277, p = 0.152). There was no difference in energy intake from the ad libitum meal (HF-3958 versus HCHO-3925 kJ; t₍₁₄₎ = 0.201, p = 0.844). CCK8/33(s) profiles were not associated with subjective appetite during early and late phases of satiety; nor was there an association between CCK8/33(s) and meal size.ConclusionsThese results demonstrate CCK levels were higher after HF meal compared to HCHO isocaloric meal. There was no association between CCK levels and intensity of satiety, or with meal size. Under these circumstances, CCK does not appear to play a unique independent role in satiety/satiation. CCK probably acts in conjunction with other peptides and the action of the stomach.     

Oxidative damage in Parkinson disease: Measurement using accurate biomarkers

Oxidative damage has been implicated in the pathogenesis of Parkinson disease (PD) but the literature data are confusing. Using products of lipid and DNA oxidation measured by accurate methods, we assessed the extent of oxidative damage in PD patients. The levels of plasma F₂-isoprostanes (F₂-IsoPs), hydroxyeicosatetraenoic acid products (HETEs), cholesterol oxidation products, neuroprostanes (F₄-NPs), phospholipase A₂ (PLA₂) and platelet activating factor–acetylhydrolase (PAF-AH) activities, urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG), and serum high-sensitivity C-reactive protein were compared in 61 PD patients and 61 age-matched controls. The levels of plasma F₂-IsoPs, HETEs, 7β-and 27-hydroxycholesterol, 7-ketocholesterol, F₄-NPs, and urinary 8-OHdG were elevated, whereas the levels of plasma PLA₂ and PAF-AH activities were lower, in PD patients compared to controls (p <  0.05). The levels of plasma F₂-IsoPs, HETEs, and urinary 8-OHdG were higher in the early stages of PD (p trend <  0.05). There was a significant negative correlation between the cumulative intake of levodopa and urinary 8-OHdG (r =  ?0.305, p =  0.023) and plasma total HETEs (r =  ?0.285, p =  0.043). Oxidative damage markers are systemically elevated in PD, which may give clues about the relation of oxidative damage to the onset and progression of PD.     

Calibrating acoustic acceleration transmitters for estimating energy use by wild adult Pacific salmon

This study is the first to calibrate acceleration transmitters with energy expenditure using a vertebrate model species. We quantified the relationship between acoustic accelerometer output and oxygen consumption across a range of swim speeds and water temperatures for Harrison River adult sockeye salmon (Oncorhynchus nerka). First, we verified that acceleration transmitters with a sampling frequency of 10 Hz could be used as a proxy for movement in sockeye salmon. Using a mixed effects model, we determined that tailbeat frequency and acceleration were positively correlated (p < 0.0001), independent of tag ID. Acceleration (p < 0.0001) was positively related to swim speed while fork length (p = 0.051) was negatively related to swim speed. Oxygen consumption and accelerometer output (p < 0.0001) had a positive linear relationship and were temperature dependent (p < 0.0001). There were no differences in swim performance (F_2,12 = 1.023, p = 0.820) or oxygen consumption (F_1,12 = 0.054, p = 0.332) between tagged and untagged individuals. Five tagged fish were released into the Fraser River estuary and manually tracked. Of the five fish, three were successfully tracked for 1 h. The above relationships were used to determine that the average swim speed was 1.25 ± 0.03 body lengths s^? 1 and cost of transport was 3.39 ± 0.17 mg O₂ kg^? 1 min^? 1, averaged across the three detected fish. Acceleration transmitters can be effectively used to remotely evaluate fine-scale behavior and estimate energy consumption of adult Pacific salmon throughout their homeward spawning migration.     

Aluminum chloride impacts dentate gyrus structure in male adult albino Wistar rats

To get better insights into the aluminum neurotoxicity, rats were treated with AlCl₃ for increasing doses and periods. Body and brain weights, plasma and brain AlCl₃ levels were assayed. Light microscopy observation of brain was performed. AlCl₃ exposure showed a significant decrease (p < 0.05) on body and brain weight with the highest dose at 18 months. Statistical analysis confirms no significant interaction during 6 months (ρ = 0.357; p > 0.05) while, significant correlation was observed during 12 (ρ = 0.836; p < 0.001) and 18 months (ρ = 0.769; p < 0.001) between body and brain weight. Plasma and brain AlCl₃ concentration increased significantly (p < 0.05) with dose and period dependent manner. Statistical analysis confirms significant interaction between brain concentrations of AlCl₃ and administrated doses during 6 (ρ = 0.969; p < 0.001), 12 (ρ = 0.971; p < 0.001) and 18 months (ρ = 0.965; p < 0.001). Similar relation was established between plasma AlCl₃ concentration and administrated doses during 6 (ρ = 0.970; p < 0.001), 12 (ρ = 0.971; p < 0.001) and 18 months (ρ = 0.964; p < 0.001). Significant relation was confirmed between plasma and brain AlCl₃ concentration during 6 (ρ = 0.926; p < 0.001), 12 (ρ = 0.983; p < 0.001) and 18 months (ρ = 0.906; p < 0.001). Morphological alterations mainly targeted the subgranular layer with modulation of the dentate gyrus appearance. This study highlights the toxic effect of AlCl₃ on the brain which may affects learning and memory and seems to be different according to dose and duration of exposure.     

The use of a mirror reduces isolation stress in horses being transported by trailer

Horse trailers are a common form of transportation for horses and ponies and often require the animal to travel alone or with a single companion. The current study investigated the effect of transporting horses alone, in company or with an acrylic safety mirror (measuring 81 cm × 61.5 cm) that provided surrogate companionship. The behavioural and physiological responses of 12 mature horses during a 30-min journey by trailer under the three treatments were compared. Behaviours (vocalisation, eating, head-tossing, pawing, and head-turning) were recorded. In order to assess circulatory changes that occur as part of the response to transport, heart rate (HR), rectal (T_r) and ear-pinna (T_p) temperatures were recorded. When travelling with a live companion significantly less time was spent vocalising (p < 0.001), head-turning (p < 0.001), head-tossing (p < 0.01) and pawing (p < 0.01); eating behaviour increased (p < 0.05). Physiological responses (increases in HR and T_r and decreases in T_p) were also significantly reduced when travelling with a live companion (p < 0.01). Travelling with the mirror did not significantly affect physiological responses compared with travelling alone, but the rise in T_r and fall in T_p was reduced (p = 0.052 and p = 0.051, respectively) and can be considered a trend. When travelling with a mirror significantly less time was spent turning the head (p < 0.01), vocalising (p < 0.05) and head-tossing (p < 0.05); eating behaviour increased (p < 0.05). The only significant difference between travelling with a live companion and a mirror was that the time spent turning the head round was less with a live companion (p < 0.05). The provision of surrogate companionship in the form of a mirror was found to be preferable to travel alone, but where possible a live companion is recommended. Isolation during transportation was found to suppress feeding behaviour. Although peripheral blood flow (T_p) has been used to assess transport stress in other species it has not previously been used in the horse. Further evaluation of this non-invasive measure is now required.     

The eccentric,concentric strength relationship of the hamstring muscles in chronic low back pain

ObjectiveThe objective of this study was to measure hamstring muscle eccentric and concentric strength in individuals with and without low back pain (LBP). Two composite scores for the relative balance of eccentric to concentric strength at the different movement velocities were calculated (the DEC and SEC), to determine whether or not self perceived pain, disability, or fear avoidance measures were associated with hamstring strength characteristics.DesignCross-sectional repeated measures design.SettingUniversity laboratory.ParticipantsFifteen individuals with chronic LBP and 15 matched controls.Main outcome measuresIsokinetic eccentric and concentric strength at 30° s^?1 and 120° s^?1_. Composite scores (DEC and SEC) based on peak torque were calculated to evaluate the relationship between the different muscle actions across the test velocities. Self report measures included the Oswestry disability index, general health and well being, fear avoidance, and pain.ResultsEccentric/concentric strength ratio at 30° s^?1 was higher for the LBP group (F(1,58) = 4.81, p = 0.032). The SEC was also higher for the LBP (F(1,58) = 5.97, p = 0.018). Fear avoidance beliefs and mental well-being were significantly associated with the SEC only in the LBP group (adjusted r² = 0.26, (F(2,27) = 5.8, p = .008). For the control group both the DEC and SEC were associated with self report measures. Matched differences between groups’ for the SEC were best explained by fear avoidance beliefs about work (adjusted r² = 0.12, F(1,28) = 5.1, p = 0.03).ConclusionReduced concentric relative to eccentric strength is best identified by the SEC. The SEC was significantly associated with impaired self report measures of fear avoidance and mental well being in individuals with LBP. Differences between groups for the SEC were best explained by fear avoidance beliefs about work.     

Role of vision and task complexity on soleus H-reflex gain

There exists extensive evidence supporting the presence of reflex modulation in humans during a variety of motor tasks. The soleus H-reflex has been shown to be modulated during static and dynamic balance conditions as well as during various motor tasks. The purpose of this study was to examine the effects of two different stance positions and visual conditions on soleus H-reflex gain in 15 apparently healthy adults (mean age = 30.27 ± 6.92 yrs). The soleus H-reflexes were examined in two experimental stance conditions: two-legged (stable) and one-leg (unstable), and two visual conditions: eyes open and eyes closed. To assess the reflex gain, subjects performed ten trials under each of the four conditions and a soleus H-reflex was elicited during the performance of each trial. For each condition the peak-to-peak amplitude of the H-reflex and the EMG activity 50 ms prior to the stimulus was recorded. Differences in the peak-to-peak amplitudes of the soleus H-reflex for the experimental conditions were compared with a 2 × 2 (Stance × Vision) repeated measures ANOVA. The level of significance was p < 0.05. Results demonstrated significant differences in reflex gain for both the vision (F_l,15 = 4.87, p < 0.05) and the stance condition (F_l,15 = 14.86, p < 0.05). Although both the stance condition and vision significantly affected the H-reflex gain, there was no interaction between these two variables (F_l,15 = 0.17). From these results, we conclude that H-reflex gain was decreased both as stance complexity increased and as visual inputs were removed. Consistent with previous reports, it may be speculated that changes in presynaptic inhibition to the soleus Ia fibers regulate these gain changes. We propose that vision and stability of stance affect soleus H-reflex gain, but do so without any interactive effects.     

Fine-scale environmental heterogeneities of tidal creeks affect distribution of crab burrows in a Chinese salt marsh

Tidal creeks are an important structure of salt marshes in estuarine ecosystems, providing valuable ecosystem services to wildlife in the estuary. To determine the effects of environmental heterogeneities within tidal creeks on the features of crab burrows, we divided a typical creek section into four parts (i.e., microhabitats): bottom, slope, edge and flat, investigated the distribution of crab burrows and sediment properties on creek sections in the Yangtze River estuary, and compared the burrow distribution in tidal creeks with that in non-creek areas. Our results showed that from the creek bottom to flat soil water content declined (F_3, 60 = 93.8, p < 0.001), and the variations of other sediment physical and chemical properties associated with the change of soil water content were significant among the microhabitats on the creek sections (p < 0.001 for pH, conductivity, and grain size). No crab burrows were found at the creek bottom. The burrows on the slope were smaller in size (p < 0.001 for burrow opening diameter) while the density was higher than that at the edge and on the flat (F_2, 45 = 31.2, p < 0.001). Moreover, although the correlations between burrow distribution and sediment properties varied among the microhabitats on the creek sections, crabs generally selected relatively solid sediments to build their burrows. On the slope, there was a significantly negative relationship between burrow density and soil water content (r² = 0.53, p < 0.001). At the edge, the correlation between total burrow opening area and soil water content was significantly negative (r² = 0.44, p < 0.002). The density of small crab burrows (<10 mm) was greater, but that of large burrows (>10 mm) was lower in tidal creeks than in non-creek habitats. Therefore, sediment properties showed a gradual transition from hydrophytic to terrestrial environments on the creek section, which caused significant differences of burrow distribution among the microhabitats. The creeks of tidal salt marshes could affect ecological processes and functioning through affecting crab burrows.     

The influence of seat height on the mechanical function of the triceps surae muscles during steady-rate cycling

The purpose of this study was to manipulate bicycle seat height in order to perturbate muscle length, contraction velocity and excitation of soleus and medial gastrocnemius muscles. One group of female riders (n = 13) rode a stationary ergometer at 200 W and a cadence of 80 rpm. Individuals rode at a self-selected seat height, a 10% lowered and 5% raised seat position. It was hypothesized that because the two muscles would operate at decreased contraction velocities at the low seat, the integrated EMG would be less for the lowest seat position. The soleus and medial gastrocnemius muscles showed a significant decrease in integrated EMG value with decreased seat height (soleus F_2,24 = 5.4, p < 0.01, gastrocnemius F_2,24 = 51.6, p < 0.0001). The combined effect of the movement at the ankle and knee joints resulted in increased length of gastrocnemius rather than shortening at the lowered seat-height position as anticipated. This suggested that there was a greater role of knee-joint angle in determining the muscle excitation for medial gastrocnemius. The original hypothesis was accepted, confirming the importance of setting proper seat height.     

Kososan,a standardized traditional Japanese herbal medicine,reverses sleep disturbance in socially isolated mice via GABAA-benzodiazepine receptor complex activation

PurposeKososan (KSS), a traditional Japanese medicine with a distinct aroma, is clinically used to treat affective disorders but its antidepressant-like effect has not been thoroughly investigated. In this study, we investigated the effects of inhaled and orally administered KSS on sleep disturbances in socially isolated mice.MethodsFour-weeks-old male ddy mice were housed either in social isolation or in groups for 4–6 weeks before the experiment. KSS was orally administered (0.5 or 1.0 g/kg) or inhaled (0.5, 1.0, or 2.5 g/0.125 m³) 60 min before pentobarbital administration. Stress levels in mice were evaluated by the duration of pentobarbital-induced sleeping time.ResultsSleeping time was shorter in socially-isolated mice than in group-housed mice. Oral and inhaled KSS prolonged sleeping time in stressed mice, but had no effect on sleeping time of group-housed mice. Prolonged sleeping time after oral KSS was significantly inhibited (p < 0.05) by bicuculline (3 mg/kg, i.p.), a GABA_A antagonist, but not by flumazenil (3 mg/kg, i.p.), a selective benzodiazepine antagonist. Prolonged sleeping time after KSS inhalation was significantly inhibited (p < 0.05) by flumazenil but not by bicuculline.ConclusionsOur findings suggest that KSS activates GABA_A-benzodiazepine receptor complex and reverses shortened pentobarbital-induced sleep caused by social isolation.     

Positive correlation between plasma nitrite and performance during high-intensive exercise but not oxidative stress in healthy men

Several studies suggest that exercise is associated with elevated oxidative stress which diminishes NO bioavailability. The aim of the present study was to investigate a potential link between NO synthesis and bioavailability and oxidative stress in the circulation of subjects performing high-intensive endurance exercise. Twenty-two male healthy subjects cycled at 80% of their maximal workload. Cubital venous blood was taken before, during and after exercise, and heparinized plasma was generated. Plasma concentrations of nitrite and nitrate were quantified by GC–MS and of the oxidative stress biomarker 15(S)-8-iso-PGF_2α by GC–MS/MS. pH and pCO₂ fell and HbO₂ increased upon exercise. The duration of the 80% phase (d80) was 740 ± 210 s. Subjects cycled at 89.2 ± 3.3% of their peak oxygen uptake. Plasma concentration of nitrite (P < 0.01) and 15(S)-8-iso-PGF_2α (P < 0.05) decreased significantly during exercise. At the end of exercise, plasma nitrite concentration correlated positively with d80 and performed work (w80) (each P < 0.05). Changes in nitrate concentration also correlated positively with d80 (P < 0.05) and w80/kg (P < 0.01). These findings provide evidence of a favorable effect of nitrite on high-intensive endurance exercise. The lack of association between 15(S)-8-iso-PGF_2α and NO bioavailability (nitrite concentration) and NO biosynthesis (nitrate concentration) suggest that oxidative stress, notably lipid peroxidation, is not linked to the l-arginine/NO pathway in healthy male subjects being on endurance exercise.     

Biceps brachii myoelectric and oxygenation changes during static and sinusoidal isometric exercises

Surface myoelectric signal changes occurring during sustained isometric contractions have been extensively studied with quantitative surface electromyography (sEMG) and are described by means of some sEMG global variables in time and frequency domain (such as the median power spectral frequency). Recently, the possibility of studying local muscle O₂ saturation during exercise using non-invasive methods has been enhanced thanks to the use of near-infrared spectroscopy (NIRS). The purpose of this work was to combine NIRS and sEMG techniques to analyze the relationship between modifications of sEMG parameters and the underlying metabolic status of the exercising biceps brachii muscle. This relationship was tested under different isometric contraction modalities, namely static (ST) at 20, 40, 60 and 80%MVC and sinusoidal (SIN) at 40 ± 20 and 60 ± 20%MVC. Results clearly indicated the presence of an initial fast phase of muscle O₂ desaturation followed by a slow phase, regardless of the contraction modality. Moreover, the initial rate of muscle O₂ desaturation was related to the level of force output (R = 0.92), but it was independent on the contraction modality (p < 0.05). Similarly, changes in sEMG parameters were related to force level (Conduction Velocity-CV vs. Force: R = 0.87; sEMG Median Frequency-MDF vs. Force: R = 0.86). The high correlation found between CV-MDF and Tissue Oxygenation Index (TOI) slope (R = 0.73 and 0.72, respectively) suggests a strong relationship between NIRS and sEMG data. This study indicates that muscle O₂ demand during isometric contractions from low to high force levels is influenced by the type of active motor units and not from the type of isometric exercise modality.     

Development of a macrophyte-based index of biotic integrity for Minnesota lakes

Traditional approaches for managing aquatic resources have often failed to account for effects of anthropogenic disturbances on biota that are not directly reflected by chemical and physical proxies of environmental condition. The index of biotic integrity (IBI) is a potentially effective assessment method to integrate ecological, functional, and structural aspects of aquatic systems. A macrophyte-based IBI was developed for Minnesota lakes to assess the ability of aquatic plant communities to indicate environmental condition. The index was developed using quantitative point intercept vegetation surveys for 97 lakes that represent a range of limnological and watershed characteristics. We followed an approach similar to that used in Wisconsin to develop the aquatic macrophyte community index (AMCI). Regional adaptation of the AMCI required the identification of species representative of macrophyte communities in Minnesota. Metrics and scaling methods were also substantially modified to produce a more empirically robust index. Regression analyses indicated that IBI scores reflected statewide differences in lake trophic state (R² = 0.57, F = 130.3, df = 1, 95, p < 0.005), agricultural (R² = 0.51, F = 83.0, df = 1, 79, p < 0.005), urban (R² = 0.22, F = 23.0, df = 1, 79, p < 0.005), and forested land uses (R² = 0.51, F = 84.7, df = 1, 79, p < 0.005), and county population density (R² = 0.14, F = 16.6, df = 1, 95, p < 0.005). Variance partitioning analyses using multiple regression models indicated a unique response of the IBI to human-induced stress separate from a response to natural lake characteristics. The IBI was minimally affected by differences in sample point density as indicated by Monte Carlo analyses of reduced sampling effort. Our analysis indicates that a macrophyte IBI calibrated for Minnesota lakes could be useful for identifying differences in environmental condition attributed to human-induced stress gradients.     

A Fraxinus excelsior L. seeds/fruits extract benefits glucose homeostasis and adiposity related markers in elderly overweight/obese subjects: A longitudinal,randomized, crossover,double-blind,placebo-controlled nutritional intervention study

PurposeThe aim of this study was to investigate the potential benefits of an extract obtained from seeds/fruits of an Oleaceae (Fraxinus excelsior L.) on glucose homeostasis and associated metabolic markers in non-diabetic overweight/obese subjects.Materials and methodsThis study was performed in 22 participants (50–80 years-old; BMI 31.0 kg/m²). The design was a longitudinal, randomized, crossover, double-blind, placebo-controlled 7-week nutritional intervention. The participants received daily 3 capsules each containing either 333 mg of an extract from Fraxinus excelsior L. seeds (Glucevia^®) or placebo capsules (control) in a random order for 3 weeks with 1 week of washout between treatments. Moreover, they followed a balanced covert energy-restricted diet (−15% energy). All variables were measured at the beginning and at the end of each period.ResultsCompared to baseline, the administration of 1 g of Glucevia^® for 3 weeks resulted in significantly lower incremental glucose area under the curve (−28.2%; p < 0.01), and significantly lower 2 h blood glucose values (−14%; p < 0.01) following an oral glucose tolerance test. No significant changes were found in the control group (−7.9% AUC, −1.6% 2 h blood glucose). Furthermore, significant differences were found between responses in the control and Glucevia^® groups with respect to serum fructosamine and plasma glucagon levels (p < 0.01 and p < 0.05, respectively). Interestingly, administration of Glucevia^® significantly increased the adiponectin:leptin ratio (p < 0.05) and decreased fat mass (p < 0.01) compared to control (p < 0.05).ConclusionThe administration of an extract from Fraxinus excelsior L. seeds/fruits in combination with a moderate hypocaloric diet may be beneficial in metabolic disturbances linked to impaired glucose tolerance, obesity, insulin resistance and inflammatory status, specifically in older adults.     

In vivo evidence that Agxt2 can regulate plasma levels of dimethylarginines in mice

Elevated plasma concentrations of the asymmetric (ADMA) and symmetric (SDMA) dimethylarginine have repeatedly been linked to adverse cardiovascular clinical outcomes. Both dimethylarginines can be degraded by alanine–glyoxylate aminotransferase 2 (Agxt2), which is also the key enzyme responsible for the degradation of endogenously formed β-aminoisobutyrate (BAIB). In the present study we wanted to investigate the effect of BAIB on Agxt2 expression and Agxt2-mediated metabolism of dimethylarginines. We infused BAIB or saline intraperitoneally for 7 days in C57/BL6 mice via minipumps. Expression of Agxt2 was determined in liver and kidney. The concentrations of BAIB, dimethylarginines and the Agxt2-specific ADMA metabolite α-keto-δ-(N(G),N(G)-dimethylguanidino)valeric acid (DMGV) was determined by LC–MS/MS in plasma and urine. As compared to controls systemic administration of BAIB increased plasma and urine BAIB levels by a factor of 26.5 (p < 0.001) and 25.8 (p < 0.01), respectively. BAIB infusion resulted in an increase of the plasma ADMA and SDMA concentrations of 27% and 31%, respectively, (both p < 0.05) and a 24% decrease of plasma DMGV levels (p < 0.05), while expression of Agxt2 was not different.Our data demonstrate that BAIB can inhibit Agxt2-mediated metabolism of dimethylarginines and show for the first time that endogenous Agxt2 is involved in the regulation of systemic ADMA, SDMA and DMGV levels. The effect of BAIB excess on endogenous dimethylarginine levels may have direct clinical implications for humans with the relatively common genetic trait of hyper-β-aminoisobutyric aciduria.     

Endurance and strength training effects on physiological and muscular parameters during prolonged cycling

PurposeThis study investigated the effects of a combined endurance and strength training on the physiological and neuromuscular parameters during a 2-h cycling test.MethodsFourteen triathletes were assigned to an endurance-strength training group and an endurance-only training group. They performed three experimental trials before and after training: an incremental cycling test to exhaustion, a maximal concentric lower-limbs strength measurement and a 2-h cycling exercise. Physiological parameters, free cycling chosen cadence and the EMG of Vastus Lateralis (VL) and Rectus Femoris (RF) were analysed during the 2-h cycling task before and after a strength training programme of 5 weeks (three times per week).ResultsThe results showed that the maximum strength and the isometric maximal voluntary contraction (isoMVC) after training were significantly higher (P < 0.01) and lower (P < 0.01) than those before training, respectively, in endurance-strength training group and endurance-only group. The physiological variables measured during the cycling tests and the progressive increase (P < 0.01) in EMGi_(VL) and EMGi_(RF) throughout the 2-h cycling test did not differ between the two groups before and after training, except for the variation of EMGi_(VL) over the cycle time which was stabilized during the second hour of the 2-h cycling test due to training in endurance-strength training group. The decrease in free cycling chosen cadence observed in pre-training (P < 0.01) was also replaced by a steady free cycling chosen cadence for the endurance-strength training group during the second hour of exercise.ConclusionThis study confirmed the decrease in the free cycling chosen cadence with exercise duration and demonstrated that a specific combined endurance and strength training can prevent this decrease during a 2-h constant cycling exercise.     

Mechanical properties of the patellar tendon in adults and children

It is not currently known how the mechanical properties of human tendons change with maturation in the two sexes. To address this, the stiffness and Young's modulus of the patellar tendon were measured in men, women, boys and girls (each group, n=10). Patellar tendon force (F_pt) was calculated from the measured joint moment during a ramped voluntary isometric knee extension contraction, the antagonist knee extensor muscle co-activation quantified from its electromyographical activity, and the patellar tendon moment arm measured from magnetic resonance images. Tendon elongation was imaged using the sagittal-plane ultrasound scans throughout the contraction. Tendon cross-sectional area was measured at rest from ultrasound scans in the transverse plane. Maximal F_pt and tendon elongation were (mean±SE) 5453±307 N and 5±0.5 mm for men, 3877±307 N and 4.9±0.6 mm for women, 2017±170 N and 6.2±0.5 mm for boys and 2169±182 N and 5.9±0.7 mm for girls. In all groups, tendon stiffness and Young's modulus were examined at the level that corresponded to the maximal 30% of the weakest participant's F_pt and stress, respectively; these were 925–1321 N and 11.5–16.5 MPa, respectively. Stiffness was 94% greater in men than boys and 84% greater in women than girls (p<0.01), with no differences between men and women, or boys and girls (men 1076±87 N/mm; women 1030±139 N/mm; boys 555±71 N/mm and girls 561.5±57.4 N/mm). Young's modulus was 99% greater in men than boys (p<0.01), and 66% greater in women than girls (p<0.05). There were no differences in modulus between men and women, or boys and girls (men 597±49 MPa; women 549±70 MPa; boys 255±42 MPa and girls 302±33 MPa). These findings indicate that the mechanical stiffness of tendon increases with maturation due to an increased Young's modulus and, in females due to a greater increase in tendon cross-sectional area than tendon length.     

Vitamin D sufficiency associates with an increase in anti-inflammatory cytokines after intense exercise in humans

The purpose of this study was to identify the influence of vitamin D status (insufficient vs. sufficient) on circulating cytokines and skeletal muscle strength after muscular injury. To induce muscular injury, one randomly selected leg (SSC) performed exercise consisting of repetitive eccentric–concentric contractions. The other leg served as the control. An averaged serum 25(OH)D concentration from two blood samples collected before exercise and on separate occasions was used to establish vitamin D insufficiency (<30 ng/mL, n = 6) and sufficiency (>30 ng/mL, n = 7) in young, adult males. Serum cytokine concentrations, single-leg peak isometric force, and single-leg peak power output were measured before and during the days following the exercise protocol. The serum IL-10 and IL-13 responses to muscular injury were significantly (both p < 0.05) increased in the vitamin D sufficient group. The immediate and persistent (days) peak isometric force (p < 0.05) and peak power output (p < 0.05) deficits in the SSC leg after the exercise protocol were not ameliorated with vitamin D sufficiency. We conclude that vitamin D sufficiency increases the anti-inflammatory cytokine response to muscular injury.     

Increasing the interval between winter outdoor exercise aggravates agonistic interactions in Hérens cows kept in tie-stalls

Cows of the dual-purpose Hérens breed are highly motivated to engage in dominance interactions and thus famous for the cow fights traditionally organised by Swiss breeders. However, this characteristic may result in excessively aggressive behaviour when cows kept in tie-stalls meet during winter outdoor exercise. This can be dangerous for both animals and breeders in terms of likelihood of injury. Regular outdoor exercise is important for the health and social behaviour of cows, and is mandatory in Switzerland. The aim of this study was to find the maximum interval between two exercise days that leads to a minimum of agonistic interactions between the cows.The study was conducted with 51 horned Hérens cows kept on six Swiss working farms. The length of the interval between days with winter outdoor exercise (daily, every third, fourth or fifth day) was experimentally increased on each farm. At the beginning of the experiment, information on social parameters (dominance index and dominance index difference) was collected for each animal and dyad. During the first 40 min of each exercise period (divided into four time-blocks of 10 min each), agonistic and allogrooming behaviour were recorded for each cow. In order to evaluate the risk of injury, all fresh wounds were noted after each exercise period, with three body parts (head, udder, rest of body) being differentiated. All data were analysed using linear mixed-effects models.The frequency of agonistic interactions increased along with the interval between two days of exercise (p < 0.001), and decreased in the course of the exercise on a given day (p < 0.001). The duration of fights increased if the interval between exercise was longer than three days. The frequency of agonistic interactions without body contact increased along with the increasing dominance index of the actor cow (from the omega to the alpha animal, p < 0.001), and, at the same time, the proportion of agonistic interactions with body contact decreased with increasing difference in dominance index between the interacting cows (p < 0.001). The risk of injury to the udder and the body (except for the head) also increased along with an increasing interval between exercise periods (udder: p < 0.001; body: p < 0.001).In conclusion, cows of the Hérens breed show pronounced agonistic behaviour after only a few days of tethering in comparison with cows who have daily winter outdoor exercise. Based on our results, the length of the interval between exercise days should be as short as possible, and in any case not longer than three days.