Ontogenetic profile of glutamate uptake in brain structures slices from rats: sensitivity to guanosine

The excitotoxicity of the neurotransmitter glutamate has been shown to be connected with many acute and chronic diseases of the CNS. High affinity sodium-dependent glutamate transporters play a key role in maintaining adequate levels of extracellular glutamate. In the present study, we used slices of striatum, hippocampus and cortex from rat brain to describe the in vitro profile of glutamate uptake during development and ageing, and its sensitivity to guanosine. In all structures, glutamate uptake was higher in immature animals. There was a maximum decrease in glutamate uptake in striatum and hippocampus in 15-month-old rats, which later increased, while in cortex there was a significant decrease in rats aged 60 days old. The effect of guanosine seems to be age and structure dependent since the increase in basal glutamate uptake was only seen in slices of cortex from 10-day-old animals.     

杜仲提取物对运动后小鼠血清尿素氮、肝糖原和血乳酸含量的影响

目的:研究杜仲醇提水溶部位(DT)对小鼠运动及运动后代谢变化的影响。方法:对小鼠负重游泳时间、运动后血清尿素氮、肝糖原、血乳酸含量进行测定。结果:杜仲醇提水溶部位不影响小鼠正常体重。延长负重游泳时间、降低运动后血清尿素氮含量,增加肝糖原含量,降低血乳酸含量。结论:杜仲醇提水溶部位具有抗疲劳作用。     

Residual effects of prior exercise and recovery on subsequent exercise-induced metabolic responses

Abstract Data on the metabolic responses to repeated endurance exercise sessions are limited. Thus, the aims of this study were to examine (1) the impact of prior exercise on metabolic responses to a subsequent exercise session and (2) the effect of different recovery periods between two daily exercise sessions on metabolic responses to the second bout of exercise. Nine male elite athletes participated in four 25-h trials: one bout of exercise (ONE), two bouts of exercise separated by 3 h of rest and one meal (SHORT), two bouts of exercise separated by 6 h of rest and two meals (LONG), and a trial with no exercise (REST). All exercise bouts consisted of 10 min cycling at 50% followed by 65 min at 75% of maximal O₂ uptake. Compared to no prior exercise (ONE), a previous bout of exercise (SHORT) was followed by higher mean O₂ uptake, heart rate (HR), rectal temperature (T_R), excess post-exercise oxygen consumption and lower respiratory exchange ratio (R) during and after a similar exercise session 3 h later. A longer rest interval between the two exercise bouts (6 h versus 3 h) and an additional meal resulted in a decrease in O₂ uptake, HR, T_R and an increase in R during the second bout of exercise, but no effects on post-exercise metabolism were found. Thus, augmented metabolic stress was observed when strenuous exercise was repeated after only 3 h of recovery, but this was attenuated when a longer recovery period including an additional meal was provided between the exercise sessions.     

Palmitic acid metabolism in the soleus muscle in vitro in hypo- and hyperthyroid rats

The aim of this study was to establish whether the rate of fatty acid (FA) incorporation and its utilization by the isolated soleus muscle is modified under conditions of thyroid hormone deficit or excess. The rate of palmitic acid (PA) uptake, oxidation and incorporation into intramuscular lipids with increasing PA concentration (0.5–1.5 mM) in the incubation medium were determined. In hypothyroid rats intramuscular triacylglycerol (TG) synthesis was increased, while the rate of PA oxidation to CO₂ and incorporation into mono- and diacylglycerols (MG/DG) and phospholipids (PL) remained unchanged. In rats with triiodothyronine (T₃) excess the rate of all processes studied was enhanced, although the percentage incorporation of PA into different classes of intramuscular lipids was fairly constant and, independently of thyroid state and FA concentration in the medium, was 56–66% for TG, 9-14% for MG/DG and 24–32% for PL. Our results thus indicate that even short-term T₃ excess accelerates the rate of FA uptake and metabolism in the oxidative soleus muscle, whereas in hypothyroid rats only intramuscular TG synthesis is affected.     

Comparison of myocardial metabolism by using PET after resuscitation between ventricular fibrillation cardiac arrest and asphyxia cardiac arrest北大核心CSCD

Objective To characterize myocardial metabolism using positron emission tomography (PET) in porcine models of ventricular fibrillation cardiac arrest (VFCA) and asphyxiation cardiac arrest (ACA) after resuscitation. Methods Thirty-Two healthy miniature pigs were randomized into two groups. The pigs of VFCA group (a = 16) were subject to programmed electric stimulation to create a ventricular fibrillation cardiac arrest, and the pigs of ACA group (n = 16) were subjected to endotracheal tube clamping to establish a cardiac arrest (CA). Once modeling was established, pigs with CA were left untreated for a period of 8 mm. Two minutes following initiation of cardiopulmonary resuscitation (CPR), defibrillation was attempted until the restoration of spontaneous circulation (ROSC) was achieved or animals died. To assess myocardial metabolism, PET was performed before modeling, 4 hrs and 24hrs after ROSC. To analyze 18F-FDG myocardial uptake in PET, the maximum standardized uptake value (SUV1) was measured. Results ROSC was obtained in 100% of pigs in VFCA group and only 50% in ACA group. The average survival time in VFCA pigs was significantly longer than that in ACA pigs (22. 63 ± 0. 95) hvs. (8. 75 ± 2. 54) h, P <0.01. VFCA pigs had better mean arterial pressure and cardiac output after ROSC than ACA pigs. Myocardial metabolism imaging using PET demonstrated that myocardial metabolism injuries after ACA were more severe and widespread than those after VFCA at 4 hrs and 24hrs after ROSC and SUV> was much higher in VFCA group than that in ACA group [4 h after ROSC: (1.9 ± 0. 3) vs. (1.0 ±0.4), P <0. 01; 24 h after ROSC: (2.4 ±0.6) vs. (1.2±0.5), P <0.01]. Conclusions Compared with VFCA, ACA causes more severe cardiac metabolism dysfunction associated with less successful resuscitation and shorter survival time; therefore they should he treated as different pathological entities.     

Energy cost and energy sources of a ballet dance exercise in female adolescents with different technical ability

This study evaluated energy cost and energy sources of a ballet exercise (grand adage) in young female dancers with different technical ability, and then related the energy sources to the subject’s and anaerobic threshold (IAT). Twenty-five dancers (13–16 years) were divided into two different technical ability groups: low-level (n = 13) and high-level (n = 12). The overall energy requirement of dance exercise (VO_2eq) was obtained by adding the amount of VO₂ during exercise above resting (aerobic source or VO_2ex) to the VO₂ up to the fast component of recovery (anaerobic alactic source or VO_2al) and to the energy equivalent of peak blood lactate accumulation (anaerobic lactic source or ) of recovery. VO_2eq of exercise amounted to 81 ± 10 and 94 ± 9 ml kg⁻¹ in low-level and high-level groups, respectively. VO_2ex represented the higher fraction (65 ± 4% and 77 ± 5%) in low-level and high-level groups, respectively, of VO_2eq in both the groups. In the low-level group the remaining fractions were: 23 ± 2 % for VO_2al and 12 ± 1% for . In high-level group the remaining fractions were: 18 ± 2 % for VO_2al and 4 ± 1% for . Between two groups, significant differences were found in VO_2ex (P < 0.01), (P < 0.01), and VO_2al (P < 0.05). IAT was 55 and 60% of for low-level and high-level dancers, respectively. Low-level dancers performed more exercise above IAT than high-level. For these reasons, it should be better to define exercise intensity according to the IAT parameter and not only to      

Scaling or normalising maximum oxygen uptake to predict 1-mile run time in boys

There is still considerable debate and some confusion as to the most appropriate method of scaling or normalizing maximum oxygen uptake (O_2max) for differences in body mass (m) in both adults and children. Previous studies on adult populations have demonstrated that although the traditional ratio standard O_2max (ml kg^–1 min^–1) fails to render O_2max independent of body mass, the ratio standard is still the best predictor of running performance. However, no such evidence exists in children. Hence, the purpose of the present study was to investigate whether the ratio standard is still the most appropriate method of normalising O_2max to predict 1-mile run speed in a group of 12-year-old children (n=36). Using a power function model and log-linear regression, the best predictor of 1-mile run speed was given by: speed (m s^–1)=55.1O_2max^0.986m^–0.96. With both the O_2max and body mass exponents being close to unity but with opposite signs, the model suggest the best predictor of 1-mile run speed is almost exactly the traditional ratio standard recorded in the units (ml kg^–1 min^–1). Clearly, reporting the traditional ratio standard O_2max, recorded in the units (ml kg^–1 min^–1), still has an important place in publishing the results of studies investigating cardiovascular fitness of both children and adults.     

Intestinal mucosa permeability following oral insulin delivery using core shell corona nanolipoparticles

Chitosan nanoparticles (NC) have excellent capacity for protein entrapment, favorable epithelial permeability, and are regarded as promising nanocarriers for oral protein delivery. Herein, we designed and evaluated a class of core shell corona nanolipoparticles (CSC) to further improve the absorption through enhanced intestinal mucus penetration. CSC contains chitosan nanoparticles as a core component and pluronic F127-lipid vesicles as a shell with hydrophilic chain and polyethylene oxide PEO as a corona. These particles were developed by hydration of a dry pluronic F127-lipid film with NC suspensions followed by extrusion. Insulin nested inside CSC was well protected from enzymatic degradation. Compared with NC, CSC exhibited significantly higher efficiency of mucosal penetration and, consequently, higher cellular internalization of insulin in mucus secreting E12 cells. The cellular level of insulin after CSC treatment was 36-fold higher compared to treatment with free insulin, and 10-fold higher compared to NC. CSC significantly facilitated the permeation of insulin across the ileum epithelia, as demonstrated in an ex vivo study and an in vivo absorption study. CSC pharmacological studies in diabetic rats showed that the hypoglycemic effects of orally administrated CSC were 2.5-fold higher compared to NC. In conclusion, CSC is a promising oral protein delivery system to enhance the stability, intestinal mucosal permeability, and oral absorption of insulin.     

Functional iron deficiency and diastolic function in heart failure with preserved ejection fraction

Background

Functional iron deficiency (FID) is an independent risk factor for poor outcome in advanced heart failure with reduced EF, but its role in heart failure with preserved EF (HFPEF) remains unclear. We aimed to investigate the impact of FID on cardiac performance determined by pressure–volume loop analysis in HFPEF.

Methods

26 HFPEF patients who showed an increase in LV stiffness by pressure–volume (PV) loop analysis obtained by conductance-catheterization, performed exercise testing, echocardiographic examination including tissue Doppler and determination of iron metabolism: serum iron, ferritin and transferrin saturation. HFPEF patients who provided ferritin < 100 μg/l or ferritin of 100–299 μg/l in combination with transferrin saturation < 20% were defined as having FID. In 14 patients the expression of transferrin receptor was determined from available endomyocardial biopsies.

Results

Fifteen out of 26 HFPEF patients showed FID without anemia. Compared to control subjects and HFPEF patients without FID, HFPEF patients with FID showed an up-regulation of the myocardial transferrin receptor expression (p < 0.05). No differences between HFPEF patients with and without iron deficiency were found in heart dimensions, systolic and diastolic function obtained by PV-loop and echocardiography analysis. According to the linear regression analysis, LV stiffness was correlated with peak oxygen uptake (r = − 0.636, p < 0.001) but not with the ferritin level or transferrin saturation. No relation was found between FID and exercise capacity. The association of LV stiffness with exercise performance was independent from the level of iron deficiency.

Conclusion

In non-anemic HFPEF patients, cardiac dysfunction and impaired exercise capacity occur independently of FID.