The Effects of Exercise and Zinc Deficiency on Some Elements in Rats

The objective of the present study was to determine the effects of exercise and zinc deficiency on some elements in rats. Forty adult male Sprague–Dawley species male rats were allocated to four groups as follows: Group 1: control, Group 2: zinc-deficient, Group 3: exercise in which exercise group fed with a normal diet, Group 4: zinc-deficient exercise, exercise group fed by a zinc-deficient diet for 15 days. After the procedure ended, rats in groups 3 and 4 were exercised on the treadmill for 60 min at a speed of 6 m/min until the exhaustion. The rats were decapitated 48 h after exercise together with their controls, and blood samples were collected to determine copper (Cu), iron (Fe), magnesium (Mg), calcium (Ca), and phosphorus (P) levels. The highest Cu and Fe values in the serum were obtained in group 2 (p < 0.01). The levels of these elements in group 4 were lower than those in group 2 and higher than the levels in groups 1 and 3 (p < 0.01). Serum Mg levels did not differ significantly between groups. Group 4 had the lowest serum Ca and P levels (p < 0.01). These same parameters in Group 2 were higher than those in group 4 but significantly lower than those in groups 1 and 3 (p < 0.01). There was no significant difference between Ca and P levels of groups 1 and 3. The results of the study indicate that zinc deficiency adversely affects copper, iron, calcium, and phosphorus mechanisms and that these adverse effects much more marked after an effort exercise.     

Effect of Selenium Supplementation on Lipid Peroxidation,Antioxidant Enzymes,and Lactate Levels in Rats Immediately After Acute Swimming Exercise

The present study aims to evaluate the effect of selenium supplementation on lipid peroxidation and lactate levels in rats subjected to acute swimming exercise. Thirty-two adult male rats of Sprague–Dawley type were divided into four groups. Group 1, control; group 2, selenium-supplemented; group 3, swimming control; group 4, selenium-supplemented swimming group. The animals in groups 2 and 4 were supplemented with (i.p.) 6 mg/kg/day sodium selenite for 4 weeks. The blood samples taken from the animals by decapitation method were analyzed in terms of erythrocyte-reduced glutathione (GSH), serum glutathione peroxidase (GPx) and superoxide dismutase (SOD), and plasma malondialdehyde (MDA) and lactate using the colorimetric method, and serum selenium values using an atomic emission device. In the study, the highest MDA and lactate values were found in group 3, while the highest GSH, GPx and SOD values were obtained in group 4 (p < 0,001). Group 2 had the highest and group 3 had the lowest selenium levels (p < 0,001). Results of the study indicate that the increase in free radical production and lactate levels due to acute swimming exercise in rats might be offset by selenium supplementation. Selenium supplementation may be important in that it supports the antioxidant system in physical activity.     

Effect of dietary fiber of “Rihane” barley grains and azoxymethane on serum and liver lipid variables in Wistar rats

The aim of the present study is to evaluate the effects of diet enriched with dietary fiber of barley variety “Rihane” and azoxymethane on serum and liver lipid variables in male rats. Forty male rats were divided into four groups and fed on control diet or experimental diet that contained control enriched with dietary fiber of barley variety “Rihane”. Animals were injected with saline (controls) or azoxymethane (20 mg/kg body weight s.c.) at 7 and 8 weeks of age. The experimental diet significantly decreased cholesterol level compared with the control diet. Rats fed with BR diet significantly increased the serum high-density lipoprotein (HDL) cholesterol and significantly decreased low-density lipoprotein (LDL) cholesterol concentrations. The experimental diet decreased the atherogenic index (p < 0.05) compared with the control diet. Whereas the azoxymethane induced a significant increase of liver lipid, serum LDL and triglyceride concentrations, but it caused a significant reduction of HDL. Consequently, the ratio of HDL/TC decreased significantly compared with the control (p < 0.05). Accordingly, these results indicated that the diet enriched with dietary fiber of barley variety “Rihane” could be effective in decreasing the atherogenic risk factors in rats whereas the use of the azoxymethane as colon-specific carcinogen substance altered the lipid metabolism.     

Effects of Acute Swimming Exercise on Some Elements in Rats

The objective of the present study is to explore the effects of acute swimming exercise on plasma levels of some elements in rats, immediately after the exercise, and 24 and 48 h later. The study included 40 adult male rats of Spraque Dawley species, which were equally allocated to four groups. Group 1: General Control Group; Group 2: Swimming Group, the group that was decapitated immediately after 30-min acute swimming exercise; Group 3: Swimming Group, the group that was decapitated 24 h after 30-min acute swimming exercise; Group 4: Swimming Group, the group that was decapitated 48 h after 30-min acute swimming exercise. Plasma copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P), selenium (Se), zinc (Zn) levels were determined according to atomic emission method in the blood samples collected from the animals by decapitation method. Measurements conducted immediately after acute swimming exercise (group 2) showed a significant decrease in Se and Zn levels (p < 0,01) and a significant increase in P levels (p < 0,01), when compared to group 1. Measurements carried out 24 h after the exercise (group 3) demonstrated a significant increase in all parameters except for Mg, in comparison to groups 1 and 2 (p < 0,01). It was seen in the measurements made 48 h after the exercise (group 4) that all parameters were restored to control values. The results of our study show that acute swimming exercise significantly changes plasma Cu, Fe, P, Se, and Zn levels.     

Seaweed meal as a protein source for the white shrimp Litopenaeus vannamei

The rhodophytes Hypnea cervicornis and Cryptonemia crenulata are abundant along the Brazilian coastline and are rich in nutrients. They may therefore be used as a source of protein in shrimp diets. The aim of the present study was to test this hypothesis. The experiment was conducted in a laboratory, where 10-day-old post-larvae aged underwent 7 days of acclimation in a 1,000 L tank. They were then kept in plastic aquariums, each containing 10 L, and 20 larvae were fed daily (10% of biomass) in four equal portions with one of four diets (five repetitions of each) for a period of 45 days. All diets contained 30% crude protein (isoprotein) and 300 kcal 100 g⁻¹ (isocaloric), with different percentages of seaweed powder: Diet “A” 39%; Diet “B” 26%, Diet “C” 13%, and Diet “D” without seaweed (control diet). Algae were collected, rinsed, dried and ground up for the feed formulations. Weight of the animals was measured at the beginning of the experiment and at 15-day intervals to assess their growth. The physico-chemical variables of the water were measured every 2 days. Final biomass, biomass gain and specific growth rate (SGR) exhibited no significant differences between treatments (P > 0.05). Survival rate was equal under the four experimental conditions, being consistent within four decimal places 95.2% to 97.00% (P > 0.05). Diets “A” and “B”, with a greater content of algae, exhibited better feed conversion (1.79:1 and 1.82:1) than Diets “C” and “D” (2.04:1 and 2.08:1) (P < 0.05). The physical-chemical variables of the water showed no significant variation and remained within the standards necessary for the wellbeing of the animals. If sufficient biomass of beached algae can be practically and economically collected, it may be used as a component in the making of shrimp feed.     

The Effects of Chromium Histidinate on Mineral Status of Serum and Tissue in Fat-Fed and Streptozotocin-Treated Type II Diabetic Rats

The present study was conducted to investigate the effects of chromium histidinate (CrHis) against experimentally induced type II diabetes and on chromium (Cr), zinc (Zn), selenium (Se), manganese (Mn), iron (Fe), and copper (Cu) in serum, liver, and kidney of diabetic rats. The male Wistar rats (n = 60, 8 weeks old) were divided into four groups. Group I received a standard diet (12% of calories as fat); group II were fed standard diet and received CrHis (110 mcg CrHis/kg body weight per day); group III received a high-fat diet (HFD; 40% of calories as fat) for 2 weeks and then were injected with streptozotocin (STZ) on day 14 (STZ, 40 mg/kg i.p.; HFD/STZ); group IV were treated as group III (HFD/STZ) but supplemented with 110 mcg CrHis/kg body weight per day. The mineral concentrations in the serum and tissue were determined by atomic absorption spectrometry. Compared to the HFD/STZ group, CrHis significantly increased body weight and reduced blood glucose in diabetic rats (p < 0.001). Concentrations of Cr, Zn, Se, and Mn in serum, liver, and kidney of the diabetic rats were significantly lower than in the control rats (p < 0.0001). In contrast, higher Fe and Cu levels were found in serum and tissues from diabetic versus the non-diabetic rats (p < 0.001). Chromium histidinate supplementation increased serum, liver, and kidney concentrations of Cr and Zn both in diabetic and non-diabetic rats (p < 0.001). Chromium supplementation increased Mn and Se levels in diabetic rats (p < 0.001); however, it decreased Cu levels in STZ-treated group (p < 0.001). Chromium histidinate supplementation did not affect Fe levels in both groups (p > 0.05). The results of the present study conclude that supplementing Cr to the diet of diabetic rats influences serum and tissue Cr, Zn, Se, Mn, and Cu concentrations.     

Effects of Ellagic Acid on Copper,Zinc, and Biochemical Values in Serum and Liver of Experimental Cholestatic Rats

Ellagic acid (EA) is a natural polyphenolic compound. Although, modulator effects of EA on copper (Cu) and zinc (Zn) levels in some liver diseases have been reported in experimental animals, its effects in obstructive jaundice (OJ) has not been clarified. We aimed to evaluate potential effects of EA on Cu and Zn levels in liver and serum of cholestatic rats. Forty Wistar albino rats were equally divided into four groups. First group was used as controls. Second group received EA (60 mg⁻¹ kg⁻¹ day⁻¹) for 8 days. Third was OJ group, and fourth group was OJ plus EA group. After 8 days, blood and liver samples were obtained. Higher serum and liver Cu and lower serum and liver Zn levels were found in OJ group (p < 0.05) compared with other groups. However, these differences reached to significant levels for Cu in serum and for Zn in lever. Higher serum copper levels were decreased, and lower liver Zn levels were increased by EA treatment in cholestatic rats (p < 0.05). Also, higher Cu/Zn ratio in OJ group was decreased by EA treatment both in liver (p < 0.05) and in serum (p < 0.05). Significantly higher serum bilirubin, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase values were found in OJ and OJ + EA groups compared with the control and EA groups (p < 0.05). In conclusion, result of the current study indicated that ellagic acid has modulator effects on Cu and Zn levels in liver and serum of cholestatic rats.     

Genetic control of aluminium tolerance in rye (Secale cereale L.)

 Aluminium (Al) tolerance in roots of two cultivars (“Ailés” and “JNK”) and two inbred lines (“Riodeva” and “Pool”) of rye was studied using intact roots immersed in a nutrient solution at a controlled pH and temperature. Both the cultivars and the inbred lines analysed showed high Al tolerance, this character being under multigenic control. The inbred line “Riodeva” was sensitive (non-telerant) at a concentration of 150 μM, whereas the “Ailes” cultivar showed the highest level of Al tolerance at this concentration. The segregation of aluminium-tolerance genes and several isozyme loci in different F₁s, F₂s and backcrosses between plants of “Ailés” and “Riodeva” were also studied. The segregation ratios obtained for aluminium tolerance in the F₂s analysed were 3 : 1 and 15 : 1 (tolerant : non-tolerant) while in backcrosses they were 1 : 1 and 3 : 1. These results indicated that Al tolerance is controlled by, at least, two major dominant and independent loci in rye (Alt1 and Alt3). Linkage analyses carried out between Al-tolerance genes and several isozyme loci revealed that the Alt1 locus was linked to the aconitase-1 (Aco1), nicotinamide adenine dinucleotide dehydrogenase-2 (Ndh2), esterase-6 (Est6) and esterase-8 (Est8) loci, located on chromosome arm 6RL. The order obtained was Alt1-Aco1-Ndh2-Est6-Est8. The Alt3 locus was not linked to the Lap1, Aco1 and Ndh2 loci, located on chromosome arms, 6RS, 6RL and 6RL respectively. Therefore, the Alt3 locus is probably on a different chromosome. Received: 18 March 1997 / Accepted: 21 March 1997     

A Pilot Study on Zinc Levels in Patients with Rheumatoid Arthritis

The aim of the study was to evaluate zinc levels in three biological compartments (serum, erythrocytes and hair) in patients with rheumatoid arthritis (RA) as compared to healthy individuals. Zinc levels in serum, erythrocytes and hair (in 74 patients with RA and 30 healthy individuals) were assessed by atomic absorption spectroscopy. The mean hair zinc content was significantly lower in RA patients as compared to healthy individuals (p < 0.001). Moreover, a positive correlation was observed in the RA patient group between the erythrocyte zinc levels and the prednisone dose (r _s = 0.48, p < 0.05), and a negative correlation was found in this population between the serum zinc levels and disease duration (r _s = −0.42, p < 0.0006). In conclusion, it seems that hair may be a useful complementary study material for evaluating “zinc status” in rheumatoid arthritis patients.     

Effect of Intraperitoneal Selenium Administration on Liver Glycogen Levels in Rats Subjected to Acute Forced Swimming

There are a few of studies examining how selenium, which is known to reduce oxidative damage in exercise, influences glucose metabolism and exhaustion in physical activity. The present study aims to examine how selenium administration affects liver glycogen levels in rats subjected to acute swimming exercise. The study included 32 Sprague–Dawley type male rats, which were equally allocated to four groups: Group 1, general control; Group 2; selenium-supplemented control (6 mg/kg/day sodium selenite); Group 3, swimming control; Group 4, selenium-supplemented swimming (6 mg/kg/day sodium selenite). Liver tissue samples collected from the animals at the end of the study were fixed in 95% ethyl alcohol. From the tissue samples buried into paraffin, 5-μm cross-sections were obtained using a microtome, put on a microscope slide, and stained with PAS. Stained preparations were assessed using a Nikon Eclipse E400 light microscope. All images obtained with the light microscope were transferred to a PC and evaluated using Clemex PE 3.5 image analysis software. The highest liver glycogen levels were found in groups 1 and 2 (p < 0.05). The levels in group 4 were lower than those in groups 1 and 2 but higher than the levels in group 3 (p < 0.05). The lowest liver glycogen levels were obtained in group 3 (p < 0.05). Results of the study indicate that liver glycogen levels that decrease in acute swimming exercise can be restored by selenium administration. It can be argued that physiological doses of selenium administration can contribute to performance.     

Treadmill exercise suppresses muscle cell apoptosis by increasing nerve growth factor levels and stimulating p-phosphatidylinositol 3-kinase activation in the soleus of diabetic rats

We investigated the effects of treadmill exercise performed regularly for 6 weeks on the levels of nerve growth factor (NGF), tyrosine kinase A and p75 receptors, phosphatidylinositol 3-kinase (PI3-K), mitogen-activated protein kinase/extracellular signal-regulated kinase (Erk) 1,2, cyclic AMP response element-binding protein (CREB), and caspase-3 in the soleus of rats with streptozotocin (STZ)-induced diabetes. Thirty-two male Sprague–Dawley rats were divided into the following four groups: (1) normal control group (NCG; n = 8), (2) normal exercise group (NEG; n = 8), (3) diabetes control group (DCG; n = 8), and (4) diabetes exercise group (DEG; n = 8). Diabetes was induced by intraperitoneal injection of STZ (55 mg/kg dissolved in 0.05 M citrate buffer, pH 4.5). Rats were subjected to treadmill exercise 5 days a week for 6 weeks. The protein level of NGF significantly increased in the NEG and DEG (p < 0.001), whereas the levels of tyrosine kinase A and p75 receptors significantly increased in the NEG (p < 0.001). The levels of t-PI3-K, p-PI3-K, and p-CREB, and the p-CREB/t-CREB ratio significantly increased in the NEG (p < 0.001, respectively). The p-PI3-K/t-PI3-K ratio significantly increased in the DEG (p < 0.001). The p-Erk1/t-Erk1 ratio significantly increased in the NEG (p < 0.001), whereas the p-Erk2/t-Erk2 ratio significantly decreased in the DCG and DEG (p < 0.001). The caspase-3 level significantly increased in the DCG compared with that in the DEG (p < 0.001). These results suggest that treadmill exercise increases NGF levels and accelerates p-PI3-K activation in order to suppress apoptotic cell death in the soleus muscle of diabetic rats.     

Training decreases muscle glycogen turnover during exercise

The present study was undertaken to determine the effects of endurance training on glycogen kinetics during exercise. A new model describing glycogen kinetics was applied to quantitate the rates of synthesis and degradation of glycogen. Trained and untrained rats were infused with a 25% glucose solution with 6-³H-glucose and U-¹⁴C-lactate at 1.5 and 0.5 μCi · min⁻¹ (where 1 Ci = 3.7 × 10¹⁰ Bq), respectively, during rest (30 min) and exercise (60 min). Blood samples were taken at 10-min intervals starting just prior to isotopic infusion, until the cessation of exercise. Tissues harvested after the cessation of exercise were muscle (soleus, deep, and superficial vastus lateralis, gastrocnemius), liver, and heart. Tissue glycogen was quantitated and analyzed for incorporation of ³H and ¹⁴C via liquid scintillation counting. There were no net decreases in muscle glycogen concentration from trained rats, whereas muscle glycogen concentration decreased to as much as 64% (P < 0.05) in soleus in muscles from untrained rats after exercise. Liver glycogen decreased in both trained (30%) and untrained (40%) rats. Glycogen specific activity increased in all tissues after exercise indicating isotope incorporation and, thus, glycogen synthesis during exercise. There were no differences in muscle glycogen synthesis rates between trained and untrained rats after exercise. However, training decreased muscle glycogen degradation rates in total muscle (i.e., the sum of the degradation rates of all of the muscles sampled) tenfold (P < 0.05). We have applied a model to describe glycogen kinetics in relation to glucose and lactate metabolism during exercise in trained and untrained rats. Training significantly decreases muscle glycogen degradation rates during exercise. Accepted: 22 May 1998     

Effects of Vitamin E and Selenium on Serum Trace and Major Elements in Horses

The combined effects of vitamin E and selenium were studied in native Anatolian horses subject to strenuous exercise. The concentrations of copper, zinc, iron, calcium, potassium, and magnesium were determined in serum by atomic absorption spectrometry in two study groups (n = 25 each), one of which served as untreated controls. After exercising the horses by running 1,500 m in about 7 min, only the copper level and the copper/zinc ratio significantly increased (p < 0.05), but the concentrations of calcium, potassium, iron, and magnesium remained unchanged. In horses treated with vitamin E and selenium, the calcium and potassium levels decreased to levels lower than those of untreated controls before and after exercise. The iron levels were not changed by exercise or treatment alone but increased when the horses had been supplemented and exercised. The copper level and the copper/zinc ration increased as a result of exercise in both treated and untreated horses. These changes suggest that supplementation with vitamin E and selenium had an important effect on the serum concentrations of calcium, potassium, copper, iron, and the copper/zinc ratio.     

Orchestrated downregulation of genes involved in oxidative metabolic pathways in obese vs. lean high-fat young male consumers

There are major variations in the susceptibility to weight gain among individuals under similar external influences (decreased physical activity and excessive calorie intake), depending on the genetic background. In the present study, we performed a microarray analysis and real-time PCR validations in order to find out differential gene expression in subcutaneous abdominal adipose tissue from two groups of subjects that despite living in similar environmental conditions such as a habitual high-fat dietary intake (energy as fat >40%) and similar moderate physical activity, some of them were successfully “resistant” (lean) to weight gain, while others were “susceptible” to fat deposition (obese). The classification of up- and downregulated genes into different categories, together with the analysis of the altered biochemical pathways, revealed a coordinated downregulation of catabolic pathways operating in the mitochondria: fatty acid β oxidation (P = 0.008), tricarboxylic acid cycle (P = 0.001), and electron transport chain (P = 0.012). At the same time, glucose metabolism (P = 0.010) and fatty acid biosynthesis (P = 0.011) pathways were also downregulated in obese compared to lean subjects. In conclusion, our data showed an orchestrated downregulation of nuclear-encoded mitochondrial gene expression. These genes are involved in cellular respiration and oxidative metabolic pathways and could play a role in the susceptibility to weight gain in some individuals.     

Generation of new transposons in vivo: an evolutionary role for the “staggered” head-to-head dimer and one-ended transposition

From a plasmid carrying the tnpA gene and one inverted repeat sequence (IR) of transposon Tn3, plasmids containing a structure characteristic of transposons, i.e., two IRs flanking a tnpA gene, were generated spontaneously in vivo. They appear to have arisen either through the formation of a “staggered” head-to-head dimer or by so-called one-ended transposition. These putative transposons could indeed transpose to, or form cointegrates with, a recipient plasmid. Based on these findings it is proposed that a primeval transposase gene and its target site evolved first, and subsequently gave rise to a “fully-fledged” transposon by head-to-head dimerization or one-ended transposition. Received: 30 October 1998 / Accepted: 1 April 1999     

Mechanoreceptive function of pectines in the Brazilian yellow scorpion Tityus serrulatus: perception of substrate-borne vibrations and prey detection

Environment perception by scorpions is an issue of great interest, and there is controversy about the use of pectines in this function. This paper investigates the mechanoreceptive function of pectines of the yellow scorpion Tityus serrulatus. The study was conducted in laboratory conditions from July 2003 to July 2004. Ninety females were maintained in six terraria (N = 15). Three of them were named “control” group (intact pectines) and the others “treatment” group (pectines covered with paraffin). Three experimental tests (an ethogram, a test of prey detection and a test of perception of substrate-borne vibrations) were performed to compare skills of animals with and without blocked pectines. The ethogram showed that treated individuals significantly reduced their exploratory activities, spent more time resting, and aggregated more than the control ones. Prey detection tests showed that the blocking of pectines made the yellow scorpions inefficient to detect and capture prey. Vibration tests showed that animals with blocked pectines also did not respond to the vibrations produced in the substrate, whereas the opposite occurred with the control group. These results suggest a mechanoreceptive function for T. serrulatus pectines, and show that the detection of ground vibrations by these structures is important for prey perception and orientation in the Brazilian yellow scorpion.     

Analysis of callouts made in relation to wild urban marmosets (Callithrix penicillata) and their implications for urban species management

In this study, we investigated what problems urban marmosets (Callithrix penicillata) face in a city environment through the analysis of responses to callouts (N = 348) made by the environmental police of Belo Horizonte, Minas Gerais, Brazil, in the period from 2002 to 2007. Our objective was to characterise the problems faced by the marmosets and human city dwellers. The environmental police responded to two types of callouts: (1) solicitation whereby a person called them to report a problem (N = 218); and (2) the report of a hurt or injured animal (N = 127). On average, one callout per week was made in relation to urban marmosets. We found no time of year effects in relation to callouts, or any effect of gender or age of the person making the callout (P > 0.05). Furthermore, we found no environmental (e.g. percentage of “green area”) or socioeconomical variables (e.g. salary levels) of the city’s administrative regions associated with callouts (P > 0.05). The majority of callouts resulted in the attempt to capture marmosets (N = 345), and usually, only one animal was captured (N = 309). Many of these animals were released into city forest fragments (N = 146). Some sick animals were sent to veterinary clinics (N = 25) whereas others or confiscated animals were sent to the government’s wildlife processing centre (N = 143). From this data, we were able to make a series of recommendation about how the management of urban marmosets could be improved.     

有氧运动改善自发性高血压大鼠肾纤维化的作用*

目的: 研究有氧运动训练对自发性高血压大鼠(SHR)肾脏纤维化影响, 探讨有氧运动对高血压肾损害的保护作用。方法: 8周龄雄性SHR和同龄Wistar京都大鼠(WKY)随机分为4组(n=6):安静WKY对照组(WKY-S)、安静SHR对照组(SHR-S)、低强度运动组(SHR-L)和中强度运动组(SHR-M)。SHR-L组、SHR-M组分别以14 m/min(最大有氧速度的35%)、20 m/min(最大有氧速度的50%)在0°坡度的运动跑步机上跑步,共运动14周,每周5次,每次60 min,WKY-S和SHR-S组安静饲养。14周后,运动训练结束72 h后检测大鼠血压;之后取血和肾脏检测血清肌酐SCr和尿素氮BUN含量,苏木精与伊红(HE)染色观察肾组织形态,Masson染色观察肾组织胶原沉积情况,计算肾脏胶原容积分数(CVF),检测肾脏 AngⅡ、AT1R、TGF-β、α-SMA、CTGF蛋白表达。结果: 与WKY-S组相比,SHR-S组的血压和血清SCr、BUN含量、肾脏CVF水平和AngⅡ、AT1R、TGF-β、α-SMA、CTGF蛋白表达均明显升高(P＜0.05);与SHR-S组相比,SHR-L组和SHR-M组血压和血清SCr、BUN含量、肾脏CVF水平和AngⅡ、AT1R、TGF-β、α-SMA、CTGF蛋白表达均明显下降(P＜0.05)且SHR-M组下降趋势更明显(P＜0.05)。结论: 有氧运动可通过抑制肾脏AngⅡ-AT1R-TGF-β通路,改善自发性高血压大鼠的肾纤维化与肾功能。     

Influence of short-term aerobic training and hydration status on tolerance during uncompensable heat stress

The purpose of the present study was to determine the separate and combined effects of a short-term aerobic training program and hypohydration on tolerance during light exercise while wearing nuclear, biological, and chemical protective clothing in the heat (40°C, 30% relative humidity). Males of moderate fitness [<50 ml · kg⁻¹ · min⁻¹ maximal O₂ consumption (V˙O_{2 max} )] were tested while euhydrated or hypohydrated by ≈2% of body weight through exercise and fluid restriction the day preceding the trials. Tests were conducted before and after either a 2-week program of daily aerobic training (1 h treadmill exercise at 65% V˙O_{2 max} for 12 days; n = 8) or a control period (n = 7), which had no effect on any measured variable. The training increased V˙O_{2 max} by 6.5%, while heart rate (f _c) and the rectal temperature (T _re) rise decreased during exercise in a thermoneutral environment. In the heat, training resulted in a decreased skin temperature and increased sweat rate, but did not affect f _c, T _re or tolerance time (TT). In both training and control groups, hypohydration significantly increased T _re and f _c and decreased the TT. It was concluded that the short-term aerobic training program had no benefit on exercise-heat tolerance in this uncompensable heat stress environment. Accepted: 12 November 1997     

Life and death near a windy oasis

We propose a simple experiment to study delocalization and extinction in inhomogeneous biological systems. The nonlinear steady state for, say, a bacteria colony living on and near a patch of nutrient or favorable illumination (“oasis”) in the presence of a drift term (“wind”) is computed. The bacteria, described by a simple generalization of the Fisher equation, diffuse, divide A→A + A, die A→ 0, and annihilate A + A→ 0. At high wind velocities all bacteria are blown into an unfavorable region (“desert”), and the colony dies out. At low velocity a steady state concentration survives near the oasis. In between these two regimes there is a critical velocity at which bacteria first survive. If the “desert” supports a small nonzero population, this extinction transition is replaced by a delocalization transition with increasing velocity. Predictions for the behavior as a function of wind velocity are made for one and two dimensions. Received: 3 August 1998 / Revised version: 17 July 1999 / Published online: 4 July 2000