Legume anchor markers link syntenic regions between Phaseolus vulgaris, Lotus japonicus, Medicago truncatula and Arachis

We have previously described a bioinformatics pipeline identifying comparative anchor-tagged sequence (CATS) loci, combined with design of intron-spanning primers. The derived anchor markers defining the linkage position of homologous genes are essential for evaluating genome conservation among related species and facilitate transfer of genetic and genome information between species. Here we validate this global approach in the common bean and in the AA genome complement of the allotetraploid peanut. We present the successful conversion of approximately 50% of the bioinformatics-defined primers into legume anchor markers in bean and diploid Arachis species. One hundred and four new loci representing single-copy genes were added to the existing bean map. These new legume anchor-marker loci enabled the alignment of genetic linkage maps through corresponding genes and provided an estimate of the extent of synteny and collinearity. Extensive macrosynteny between Lotus and bean was uncovered on 8 of the 11 bean chromosomes and large blocks of macrosynteny were also found between bean and Medicago. This suggests that anchor markers can facilitate a better understanding of the genes and genetics of important traits in crops with largely uncharacterized genomes using genetic and genome information from related model plants.

Chemokines are elevated in plasma after strenuous exercise in humans

During the last few years much attention has been paid to the chemokines. Chemokine receptors are necessary to render a target permissive for infection by the human immunodeficiency virus (HIV) and high concentrations of chemokines have been shown to protect against the progression of HIV disease towards death. In the present study, we investigated the capability of strenuous exercise to induce elevated plasma concentrations of the chemokines interleukin (IL)-8, macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta. Eight male athletes completed the Copenhagen Marathon 1997. Blood was sampled before, immediately after the run and every 30 min during a 4 h recovery period. Plasma chemokine concentrations were measured using enzyme-linked immunosorbent assays. The IL-8, MIP-1 alpha and MIP-1 beta concentrations all peaked 0.5 h after the run when they were 6.7-fold, 3.5-fold and 4.1-fold increased, respectively. The elevated concentrations of chemokines in plasma after exercise could have implications for HIV-infected individuals; a possibility that needs further investigation.

A novel device for measuring the effect of cholesterol on the release of oxygen from red blood cells into myocardial tissue

A novel method has been devised to measure the effect of cholesterol on the release of oxygen (O2) from the red blood cell (RBC) into a tailored environment, which can be made to mimic myocardial tissue. Cholesterol affects the cell membrane of the RBC and thus the release of O2 into tissue. While this is true of all tissue, the myocardium is especially sensitive because of its critical nature, its high O2 requirements, and the shortness of time that arterial blood spends in the muscle. Calculations are presented that show that the release time for O2 from RBCs is close to the residence time of the RBC in the coronary system. Sequential measurements of blood oxygen saturation (SO2) are made when oxygenated blood is subjected to conditions similar to those in the myocardium. The natural logarithm of the relative value of the SO2 at time t compared with the initial value of the SO2 can be fitted to a straight line whose slope is proportional to the parameters of the RBC membrane, the sample size, the hematocrit, and the diffusion parameters of the apparatus. This value is used to estimate the effects of cholesterol-lowering treatments on O2 release. This test will serve as a valuable adjunct to or replacement for stress tests in the evaluation of coronary artery disease, especially in patients whose physical conditions make standard stress testing painful or risky.

Training and natural immunity: effects of diets rich in fat or carbohydrate

The purpose of the study was to investigate whether a carbohydrate-rich versus fat-rich diet influenced the effect of training on the immune system. Ten untrained young men ingested a carbohydrate-rich diet [65 energy percent (E%) carbohydrate] and ten subjects a fat-rich diet (62E% fat) while endurance training was performed 3-4 times a week for 7 weeks. Maximal oxygen uptake increased by 11% in both groups. Blood samples for immune monitoring were collected before and at the end of the study. Blood samples were also collected, in parallel, from 20 age-matched subjects, and data from these subjects were used to eliminate day-to-day variation in the immunological tests. Independently of diet, training increased the percentage of CD3-CD16+ CD56+ natural killer (NK) cells from [mean (SEM)] 14 (1) % to 20 (3) % (P = 0.05), whereas the NK-cell activity, either unstimulated or stimulated with interleukin (IL)-2 or interferon (IFN)-alpha, did not change. Furthermore, training did not influence the percentages of CD3+, CD4+, CD8+, CD19+ or CD14+ cells. However, when the two diet groups were compared, it was found that the NK-cell activity had increased in the group on the carbohydrate-rich diet [from 16 (3)% to 27 (2)%] and decreased in the group on the fat-rich diet [from 26 (2)% to 20 (4)%] in response to training. The effect of training on unstimulated NK-cell activity was significantly different between the groups (P = 0.007). These data indicate that diet manipulation during training may influence natural immunity, and suggest that ingestion of a fat-rich diet during training is detrimental to the immune system compared to the effect of a carbohydrate-rich diet.

Pro- and anti-inflammatory cytokine balance in strenuous exercise in humans

1. The present study investigates to what extent and by which time course prolonged strenuous exercise influences the plasma concentration of pro-inflammatory and inflammation responsive cytokines as well as cytokine inhibitors and anti-inflammatory cytokines. 2. Ten male subjects (median age 27.5 years, range 24-37) completed the Copenhagen Marathon 1997 (median running time 3 : 26 (h : min), range 2 : 40-4 : 20). Blood samples were obtained before, immediately after and then every 30 min in a 4 h post-exercise recovery period. 3. The plasma concentrations of tumour necrosis factor (TNF)alpha, interleukin (IL)-1beta, IL-6, IL-1ra, sTNF-r1, sTNF-r2 and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA). The highest concentration of IL-6 was found immediately after the race, whereas IL-1ra peaked 1 h post exercise (128-fold and 39-fold increase, respectively, as compared with the pre-exercise values). The plasma level of IL-1beta, TNFalpha, sTNF-r1 and sTNF-r2 peaked in the first hour after the exercise (2. 1-, 2.3-, 2.7- and 1.6-fold, respectively). The plasma level of IL-10 showed a 27-fold increase immediately post exercise. 4. In conclusion, strenuous exercise induces an increase in the pro-inflammatory cytokines TNFalpha and IL-1beta and a dramatic increase in the inflammation responsive cytokine IL-6. This is balanced by the release of cytokine inhibitors (IL-1ra, sTNF-r1 and sTNF-r2) and the anti-inflammatory cytokine IL-10. The study suggests that cytokine inhibitors and anti-inflammatory cytokines restrict the magnitude and duration of the inflammatory response to exercise.

Muscle glycogen accumulation after a marathon: roles of fiber type and pro- and macroglycogen

Muscle glycogen remains subnormal several days after muscle damaging exercise. The aims of this study were to investigate how muscle acid-soluble macroglycogen (MG) and acid-insoluble proglycogen (PG) pools are restored after a competitive marathon and also to determine whether glycogen accumulates differently in the various muscle fiber types. Six well-trained marathon runners participated in the study, and muscle biopsies were obtained from the vastus lateralis of the quadriceps muscle before, immediately after, and 1, 2, and 7 days (days 1, 2, and 7, respectively) after the marathon. During the race, 56 +/- 3.8% of muscle glycogen was utilized, and a greater fraction of MG (72 +/- 3.7%) was utilized compared with PG (34 +/- 6.5%). On day 2, muscle glycogen and MG values remained lower than prerace values, despite a carbohydrate-rich diet, but they had both returned to prerace levels on day 7. The PG concentration was lower on day 1 compared with before the race, whereas there were no significant differences between the prerace PG concentration and the concentrations on days 2 and 7. On day 2 the glycogen concentration was particularly low in the type I fibers, indicating that local processes are important for the accumulation pattern. We conclude that a greater fraction of human muscle MG than of PG is utilized during a marathon and that accumulation of MG is particularly delayed after the prolonged exercise bout. Furthermore, factors produced locally appear important for the glycogen accumulation pattern.

Competitive sustained exercise in humans, lymphokine activated killer cell activity, and glutamine--an intervention study

This study examined whether oral glutamine supplementation abolishes some of the exercise-induced changes in lymphocyte functions following long-term intense exercise. A group of 16 marathon runners participating in The Copenhagen Marathon 1996 were placed randomly in either a placebo (n = 7) or a glutamine receiving group (n = 9). Each subject received four doses of either placebo or glutamine (100 mg x kg(-1)) administered at 0, 30, 60, and 90-min post-race. In the placebo group the plasma glutamine concentrations were lower than pre-race values during the post-exercise period [mean 647 (SEM 32) compared to 470 (SEM 22) micromol x 1(-1) 90-min post-race, P < 0.05] whereas glutamine supplementation maintained the plasma glutamine concentration (at approximately 750 micromol x 1(-1)). Glutamine supplementation in vivo had no effect on the lymphokine activated killer (LAK) cell activity, the proliferative responses or the exercise-induced changes in concentrations or percentages of any of the leucocyte subpopulations examined. Glutamine addition in in vitro studies enhanced the proliferative response in both groups. These data would suggest that decreased plasma glutamine concentrations post-exercise are not responsible for exercise-induced decrease in LAK activity and that the influence of glutamine in vitro is not dependent on the plasma glutamine concentration at the time of sampling.

Glutamine, exercise, and the immune system--is there a link?

Glutamine is known to be important for cells replicating in culture. It has been proposed that the decrease in plasma glutamine concentration in relation to catabolic conditions, including strenuous exercise, resulting in a lack of glutamine for cells of the immune system, is responsible for the transient postexercise immunosuppression. This review discusses the potential role of glutamine on the postexercise in-vitro changes in immune parameters. Furthermore, the value of glutamine as a nutritional supplement to athletes and the possible influence on these parameters is reviewed.

Effect of glutamine supplementation on changes in the immune system induced by repeated exercise

The ability of lymphocytes to proliferate and generate lymphokine activated killer (LAK) cell activity in vitro is dependent on glutamine. In relation to intense exercise the lymphocyte concentration, the proliferative response, the natural killer and LAK cell activity, and the plasma glutamine concentration decline. It has been hypothesized that in relation to physical activity a lack of glutamine may temporarily affect the function of the immune system.

PURPOSE

The purpose of this study was to examine the influence of glutamine supplementation on exercise-induced immune changes.

METHODS

In a randomized cross-over placebo-controlled study, eight healthy male subjects performed three bouts of ergometer bicycle exercise lasting 60, 45, and 30 min at 75% of their VO2max separated by 2 h of rest.

RESULTS

The arterial plasma glutamine concentration declined from 508 +/- 35 (pre-exercise) to 402 +/- 38 microM (2 h after the last exercise bout) in the placebo trial and was maintained above pre-exercise levels in the glutamine supplementation trial. The numbers of circulating lymphocytes and the phytohemagglutinin-stimulated lymphocyte proliferative response declined 2 h after, respectively, during each bout of exercise, whereas the LAK cell activity declined 2 h after the third bout. Glutamine supplementation in vivo, given in the described doses at the specific times, did not influence these changes.

CONCLUSION

The present study does not appear to support the hypothesis that those aspects of postexercise immune changes studied are caused by decreased plasma glutamine concentrations.

The cytokine response to strenuous exercise

Strenuous exercise is accompanied by an increase in circulating proinflammatory and inflammation responsive cytokines, having some similarities with the response to sepsis and trauma. The sequential release of tumour necrosis factor-alpha, interleukin (IL) 1 beta, IL-6, and IL-1 receptor antagonist (IL-1ra) in the blood is comparable to that observed in relation to bacterial diseases. Eccentric exercise is associated with an increase in serum IL-6 concentrations and is significantly correlated with the concentration of creatine kinase (CK) in the following days, whereas no changes are found after the concentric exercise; this demonstrates a close association between exercise-induced muscle damage and increased serum levels of IL-6. The time course of cytokine production, the close association with muscle damage, and the finding of mRNA-IL-6 in skeletal muscle biopsies after intense exercise all support the idea that during eccentric exercise myofibers are mechanically damaged and that this process stimulates the local production of inflammatory cytokines. It remains to be shown whether systemic endotoxemia during exercise is also a cause of elevated levels of cytokines in the plasma. The present review also discusses the possible roles of protein breakdown, delayed onset muscle soreness, and clinical implications of the acute-phase response following exercise.

Evidence that interleukin-6 is produced in human skeletal muscle during prolonged running

1. This study was performed to test the hypothesis that inflammatory cytokines are produced in skeletal muscle in response to prolonged intense exercise. Muscle biopsies and blood samples were collected from runners before, immediately after, and 2 h after a marathon race. 2. The concentration of interleukin (IL)-6 protein in plasma increased from 1.5 +/- 0.7 to 94.4 +/- 12.6 pg ml-1 immediately post-exercise and to 22.1 +/- 3.8 pg ml-1 2 h post-exercise. IL-1 receptor antagonist (IL-1ra) protein in plasma increased from 123 +/- 23 to 2795 +/- 551 pg ml-1, and increased further to 4119 +/- 527 pg ml-1 2 h post-exercise. 3. The comparative polymerase chain reaction technique was used to evaluate mRNA for IL-6, IL-1ra, IL-1beta and tumour necrosis factor (TNF)-alpha in skeletal muscle and blood mononuclear cells (BMNC) (n = 8). Before exercise, mRNA for IL-6 could not be detected either in muscle or in BMNC, and was only detectable in muscle biopsies (5 out of 8) after exercise. Increased amounts of mRNA for IL-1ra were found in two muscle biopsies and five BMNC samples, and increased amounts of IL-1beta mRNA were found in one muscle and four BMNC samples after exercise. TNF-alpha mRNA was not detected in any samples. 4. This study suggests that exercise-induced destruction of muscle fibres in skeletal muscles may trigger local production of IL-6, which stimulates the production of IL-1ra from circulating BMNC.

Recovery of the immune system after exercise

In the recovery phase after intense exercise is found suppressed blood concentration of lymphocytes, suppressed natural immunity of blood lymphocytes, decreased concentration of secretory IgA in mucosa, but increased blood concentration of neutrophils and increased levels in the blood of inflammatory cytokines. Thus, after intense long-term exercise, the immune system is characterized by concomitant inflammation and temporary suppression of the cellular immune system, the most pronounced findings being 2-4 h after the exercise. The underlying mechanisms are multifactorial and include neuroendocrinological and metabolic factors. High levels of cytokines, especially interleukin-6, are found in the recovery period after eccentric exercise, and it has been demonstrated that a close association exists between muscle damage and increased levels of interleukin-6.

Impaired muscle glycogen resynthesis after a marathon is not caused by decreased muscle GLUT-4 content

Our purpose was to investigate whether the slow rate of muscle glycogen resynthesis after a competitive marathon is associated with a decrease in the total muscle content of the muscle glucose transporter (GLUT-4). Seven well-trained marathon runners participated in the study, and muscle biopsies were obtained from the lateral head of the gastrocnemius muscle before, immediately after, and 1, 2, and 7 days after the marathon, as were venous blood samples. Muscle GLUT-4 content was unaltered over the experimental period. Muscle glycogen concentration was 758 +/- 53 mmol/kg dry weight before the marathon and decreased to 148 +/- 39 mmol/kg dry weight immediately afterward. Despite a carbohydrate-rich diet (containing at least 7 g carbohydrate.kg body mass-1.day-1), the muscle glycogen concentration remained 30% lower than before-race values 2 days after the race, whereas it had returned to before-race levels 7 days after the race. We conclude that the total GLUT-4 protein content is unaltered in the lateral gastrocnemius after a competitive marathon and that the slow recovery of muscle glycogen after the race apparently involves factors other than changes in the total content of this protein.

Prolonged submaximal eccentric exercise is associated with increased levels of plasma IL-6

To study the relationship between exercise-related muscle proteolysis and the cytokine response, a prolonged eccentric exercise model of one leg was used. Subjects performed two trials [a branched-chain amino acid (BCAA) supplementation and a control trial]. The release of amino acids from muscle during and after the eccentric exercise was decreased in the BCAA trial, suggesting a suppression of net muscle protein degradation. The plasma concentrations of interleukin (IL)-6 increased from 0.75 +/- 0.19 (preexercise) to 5.02 +/- 0.96 pg/ml (2 h postexercise) in the control trial and in the BCAA supplementation trial from 1.07 +/- 0.41 to 4.15 +/- 1.21 pg/ml. Eccentric exercise had no effect on the concentrations of neutrophils, lymphocytes, CD16+/CD56+, CD4+, CD8+, CD14+/CD38+, lymphocyte proliferative response, or cytotoxic activities. BCAA supplementation reduced the concentration of CD14+/CD38+ cells. This study shows that the concentration of IL-6 in plasma is increased after prolonged eccentric exercise and suggests that the cytokine response is independent of the muscle proteolysis that occur during exercise.

Exercise-induced immunomodulation--possible roles of neuroendocrine and metabolic factors

Acute muscular exercise induces an increased neutrophil count concomitant with recruitment of natural killer (NK), B and T cells to the blood as reflected by an elevation in the total lymphocyte count. Meanwhile, following intense exercise of long duration the lymphocyte count declines, non-MHC-restricted cytotoxicity is suppressed, but the neutrophil concentration increases. In relation to eccentric exercise involving muscle damage, the plasma concentrations of interleukin-1, interleukin-6 and the tumor necrosis factor are elevated. In this review we will propose a model based on the possible roles that stress hormones play a mediating the exercise- related immunological changes: adrenaline and to a lesser degree noradrenaline are responsible for the immediate effects of exercise on lymphocyte subpopulations and cytotoxic activities. The increase in catecholamines and growth hormone mediate the acute effects of exercise on neutrophils, whereas cortisol may be responsible for maintaining lymphopenia and neutrocytosis after exercise of long duration. Lastly, the role of beta-endorphin is less clear, but the cytokine response is closely related to muscle damage and stress hormones do not seem to be directly involved in the elevated cytokine level. Other possible mechanisms of exercise-induced immunomodulation may include the so-called glutamine hypothesis, which is based on the fact that skeletal muscle is an important source of glutamine production and that lymphocytes are dependent on glutamine for optimal growth. Furthermore, physiological changes during exercise, e.g. increased body temperature and decreased oxygen saturation may also in theory contribute to the exercise-induced immunological changes.

Immunity in athletes

It has become clear that the immune system responds to increased physical activity and may be given some of the credit for exercise-related reduction in illness. In contrast, it has repeatedly been shown that intense exercise causes immunosuppression. In essence the immune system is enhanced during moderate and severe exercise, and only intense long-duration exercise is followed by immunodepression. The latter include suppressed concentration of lymphocytes, suppressed natural killer and lymphokine activated killer cytotoxicity and secretory IgA in mucosa. Whether or not the "open window" in the immune system occurs is dependent on the intensity and duration of exercise. One reason for the "overtraining effect" seen in elite athletes could be that this window of opportunism for pathogens is longer and the degree of immunosuppression more pronounced. It is being hypothesized that severe immunodepression may occur if athletes does not allow the immune system to recover, but initiate a new bout of exercise while still immunodepressed. It has also been suggested that neutrophils serve as a last line of defence. The removal of this back-up system following extreme activity would be compatible with the propensity of "overtrained" individuals to develop upper respiratory tract infections.

Glutamine, lymphocyte proliferation and cytokine production

The present in vitro study was conducted to examine how glutamine influences the lymphocyte function. Glutamine had no effect on the production of interleukin-1 beta, interleukin-6 or tumour necrosis factor-alpha, but influenced the production of interleukin-2 and interferon-gamma. Glutamate, leucine, isoleucine and valine (substrates for glutamine production), or the combination of glutamate and leucine, did not influence the lymphocyte proliferative response or the cytokine production. In conclusion, glutamine influenced the production of some T-cell-derived cytokines, and is thereby important for optimal lymphocyte proliferation. Furthermore, the results show that lymphocytes are not capable of producing glutamine.

The immune system and serum glutamine during a triathlon

This study examined the influence of a triathlon on the immune system and on serum amino acid concentrations. Eight male triathletes swam 2500 m, bicycled 81 km, and ran 19 km. The concentration of total serum amino acids decreased during the race, with the lowest values occurring 2 h postexercise. Similarly, serum glutamine concentration declined from 468 (SEM 24) (prerace) to 318 (SEM 20) mumol-1 (2 h postrace) and the natural killer (NK) and lymphokine activated killer (LAK) cell activities were suppressed 2 h postexercise (P < 0.05). Blood mononuclear cell proliferation decreased during exercise with the lowest value observed after running. The leucocyte concentration increased during and after exercise due to an increase in the concentration of neutrophils and monocytes. There was no significant change in lymphocyte concentration during or after the exercise. The plasma concentration of interleukin-6 did not change and the plasma concentration of interleukin-1 beta and tumor necrosis factor-alpha were below detection limits. The LAK cell cytotoxicity, but not NK cell activity or proliferative response, was significantly correlated with serum glutamine concentrations (r = 0.39, P < 0.01). This study confirms that prolonged endurance exercise results in changes in the cytotoxic function of the NK and LAK cells as well as the proliferative response. The time-course of changes in serum glutamine concentrations were best parallelled by changes in LAK cell activities.

Effects of glutamine on the immune system: influence of muscular exercise and HIV infection

Glutamine increased the proliferative response and the lymphokine-activated killer cell activity of blood mononuclear cells isolated from normal healthy subjects (n = 6) in a dose-dependent manner, with optimum at 0.3-1.0 mM. The relative fraction of CD3+, CD4+, CD8+, CD14+, CD16+, and CD19+ cells was not changed by glutamine at a concentration of 0.6 mM, except in the phytohemagglutinin-stimulated proliferation experiment where the fraction of CD4+, and therefore CD3+ cells, increased. The natural killer cell activity was not influenced by glutamine. Human immunodeficiency virus (HIV)-seropositive subjects (n = 8) who performed concentric bicycle exercise for 1 h at 75% of maximal O2 consumption had an overall lower phytohemagglutinin-stimulated proliferative response, compared with the HIV-seronegative control group (n = 7). The proliferation during exercise was lower in both the HIV-seropositive and the HIV-seronegative group. Addition of glutamine in vitro did not normalize the lower proliferation in the HIV-seropositive group or the attenuated proliferation seen during exercise in both groups.

[Testing an ultrasonic scanner for determination of urinary bladder volume]

Bladderscan BVI 2000 is a portable ultrasound scanner, specially constructed for determination of bladder volume. We have tested this scanner for accuracy, systematic errors and the training required to use it. The bladder volumes measured by ultrasound scanning were compared with the true volumes. Fifty-six measurements were made. We found the accuracy of BVI 2000 sufficient to determine bladder volumes as either small or large. We found no systematic errors. No special training is required to use the scanner. The device is thus useful in most clinical situations when greater accuracy than indicated here is not necessary.