Roger D. Hurst

Short-term blackcurrant extract consumption modulates exercise-induced oxidative stress and lipopolysaccharide-stimulated inflammatory responses.

Exercise-induced oxidative stress is instrumental in achieving the health benefits from regular exercise. Therefore, inappropriate use of fruit-derived products (commonly applied as prophalytic antioxidants) may counteract the positive effects of exercise. Using human exercise and cellular models we found that 1) blackcurrant supplementation suppressed exercise-induced oxidative stress, e.g., plasma carbonyls (0.9 +/- 0.1 vs. 0.6 +/- 0.1 nmol/mg protein, placebo vs. blackcurrant), and 2) preincubation of THP-1 cells with an anthocyanin-rich blackcurrant extract inhibited LPS-stimulated cytokine secretion [TNF-alpha (16,453 +/- 322 vs. 10,941 +/- 82 pg/ml, control vs. extract, P < 0.05) and IL-6 (476 +/- 14 vs. 326 +/- 32 pg/ml, control vs. extract, P < 0.05)] and NF-kappaB activation. In addition to its antioxidant and anti-inflammatory properties, we found that postexercise plasma collected after blackcurrant supplementation enhanced the differential temporal LPS-stimulated inflammatory response in THP-1 cells, resulting in an early suppression of TNF-alpha (1,741 +/- 32 vs. 1,312 +/- 42 pg/ml, placebo vs. blackcurrant, P < 0.05) and IL-6 (44 +/- 5 vs. 36 +/- 3 pg/ml, placebo vs. blackcurrant, P < 0.05) secretion after 24 h. Furthermore, by using an oxidative stress cell model, we found that preincubation of THP-1 cells with hydrogen peroxide (H(2)O(2)) prior to extract exposure caused a greater suppression of LPS-stimulated cytokine secretion after 24 h, which was not evident when cells were simultaneously incubated with H(2)O(2) and the extract. In summary, our findings support the concept that consumption of blackcurrant anthocyanins alleviate oxidative stress, and may, if given at the appropriate amount and time, complement the ability of exercise to enhance immune responsiveness to potential pathogens.

Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage.

BackgroundExercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise.MethodsIn a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA.ResultsA significant (pu2009<u20090.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (pu2009=u20090.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (pu2009<u20090.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery.ConclusionsThis study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength. This effect, although independent of the beverage’s inherent antioxidant capacity, appears to involve an up-regulation of adaptive processes, i.e. endogenous antioxidant processes, activated by the combined actions of the eccentric exercise and blueberry consumption. These findings may benefit the sporting community who should consider dietary interventions that specifically target health and performance adaptation.

Blueberry fruit polyphenolics suppress oxidative stress-induced skeletal muscle cell damage in vitro.

Skeletal muscle damage can result from disease and unaccustomed or excessive exercise. Muscle dysfunction occurs via an increased level of reactive oxygen species and hence there is potential in antioxidants as amelioration strategies. We explored the putative benefit of fruit polyphenolic extracts in reducing the susceptibility of skeletal muscle cells to oxidative stress. Muscle myotubes were simultaneously challenged with fruit extracts (1-50 microg/mL) and calcium ionophore (A23187), hydrogen peroxide, or 2,4-dinitrophenol and damage monitored by release of cytosolic enzymes. A blueberry fruit extract displayed a potent and significant dose-dependent protective capacity. Evaluation of the protective capacity of anthocyanin sub-extracts of blueberry fruit and pure individual glycosides, with identification of extract polyphenolic components using MS, suggested that malvidin galactoside and/or glucoside were the active compounds. These in vitro data support the concept that blueberry fruits or derived foods rich in malvidin glycosides may be beneficial in alleviating muscle damage caused by oxidative stress. More research on the benefits of blueberry fruit consumption in human intervention studies is warranted.

Blackcurrant proanthocyanidins augment IFN-γ-induced suppression of IL-4 stimulated CCL26 secretion in alveolar epithelial cells.

Epidemiological studies reveal that fruit consumption reduces the prevalence of airway inflammation and childhood asthma. In particular, blackcurrant polyphenolic extracts have been shown to alleviate lung inflammation. Since IL-4-stimulated eotaxin-3 (CCL26) secretion is a major factor in the continuous eosinophil recruitment observed in atopic asthma, our focus was to evaluate the effectiveness of blackcurrant polyphenolic compounds on CCL26 secretion in human alveolar epithelial cells. Our results indicate that a proanthocyanin-enriched blackcurrant extract (BC-P), but not anthocyanin-enriched blackcurrant extract suppressed both IL-4- and IL-13-stimulated CCL26 secretion in a dose-dependent manner. Furthermore pre-incubation of cells with BC-P caused a time-dependent suppression of IL-4-stimulated CCL26 secretion. Moreover, epigallocatechin (EGC), and to a lesser extent epicatechin, metabolites identified in the proanthocyanidin extract, suppressed IL-4-stimulated CCL26 secretion. EGC was also effective at reducing the cellular phosphorylated STAT-6/STAT-6 ratio. Furthermore, both BC-P and purified EGC potentiated the ability of IFN-gamma to suppress IL-4-stimulated CCL26 secretion. The progression of an allergic immune response is complex, identifying plant compounds that target specific cellular events and complement the bodys own immune actions is important for the development of functional foods. Our findings support the potential for blackcurrant polyphenolic compounds to reduce eosinophil recruitment and alleviate eosinophilic-driven airway inflammation.

Standardising the lactulose mannitol test of gut permeability to minimise error and promote comparability.

Background Lactulose mannitol ratio tests are clinically useful for assessing disorders characterised by changes in gut permeability and for assessing mixing in the intestinal lumen. Variations between currently used test protocols preclude meaningful comparisons between studies. We determined the optimal sampling period and related this to intestinal residence. Methods Half-hourly lactulose and mannitol urinary excretions were determined over 6 hours in 40 healthy female volunteers after administration of either 600 mg aspirin or placebo, in randomised order at weekly intervals. Gastric and small intestinal transit times were assessed by the SmartPill in 6 subjects from the same population. Half-hourly percentage recoveries of lactulose and mannitol were grouped on a basis of compartment transit time. The rate of increase or decrease of each sugar within each group was explored by simple linear regression to assess the optimal period of sampling. Key Results The between subject standard errors for each half-hourly lactulose and mannitol excretion were lowest, the correlation of the quantity of each sugar excreted with time was optimal and the difference between the two sugars in this temporal relationship maximal during the period from 2½-4 h after ingestion. Half-hourly lactulose excretions were generally increased after dosage with aspirin whilst those of mannitol were unchanged as was the temporal pattern and period of lowest between subject standard error for both sugars. Conclusion The results indicate that between subject variation in the percentage excretion of the two sugars would be minimised and the differences in the temporal patterns of excretion would be maximised if the period of collection of urine used in clinical tests of small intestinal permeability were restricted to 2½-4 h post dosage. This period corresponds to a period when the column of digesta column containing the probes is passing from the small to the large intestine.

The effect of aspirin and smoking on urinary excretion profiles of lactulose and mannitol in young women: toward a dynamic, aspirin augmented, test of gut mucosal permeability.

Backgroundu2002 We explored the temporal dynamics of the lactulose mannitol test and the influence of a single dose of aspirin.

Plant-derived Foods for the Attenuation of Allergic Airway Inflammation

Asthma is an allergy-mediated inflammatory disease characterised by infiltration of the airway with mast cells, lymphocytes, and eosinophils. The disease is induced by co-ordination of T-helper cell type 2 (Th2) cytokines and inflammatory signal molecules. Fruits and vegetables are a rich source of polyphenolic bioactive compounds, which have been observed to have health-promoting properties when consumed by humans. In particular, fruit-derived proanthocyanins and anthocyanins have been found to attenuate lung inflammation. Epidemiological studies have revealed correlations between fruit consumption and a lower prevalence of respiratory symptoms and lower incidence of non-specific lung diseases. In this review we summarise the current understanding of the pathophysiologic mechanism(s) involved in the development of allergic airway disease. We also review evidence of the beneficial effects of plant-derived foods, their components and metabolites in allergic airway inflammation arising from in vitro and rodent studies, epidemiological studies and human intervention trials. The mechanism, biological relevance and functional benefits, such as immune modulation (e.g. reduction in cytokine and eotaxin production), antioxidant ability, tissue remodelling and tight junction function are also discussed.

Evaluating the health benefits of fruits for physical fitness: A research platform

To evaluate the health promoting attributes of fruits and their compounds the New Zealand Institute for Plant & Food Research Ltd (PFR) is using exercise as a model for oxidative stress and immune depression. Regular exercise has health benefits believed to be derived from adaptive responses to moderate oxidative stress. However, following exhaustive or unaccustomed exercise, excessive and prolonged oxidative stress and inflammation can be detrimental and the right balance of modulation from nutritional support via fruit phytochemicals (and vitamins) may prevent damage, aid recovery, and/or enhance muscular and immune function. We have developed a research platform to evaluate physical health, performance and recovery to position new fruit varieties in this area. Utilising compositional analysis of fruit extracts, in vitro screening of muscle cells, electrically stimulated muscle ex vivo, and animal and human intervention and exercise trials, we are evaluating the physical health-promoting effects of polyphenolic phytochemicals derived from fruit, particularly berry fruits. Our research demonstrates that certain fruits may complement the benefits of regular exercise through appropriate modulation of excessive oxidative stress and inflammation.

Post-exercise skeletal muscle glycogen related to plasma cytokines and muscle IL-6 protein content, but not muscle cytokine mRNA expression

Objectives The purpose of this study was to correlate post-exercise muscle glycogen levels with changes in plasma cytokine, and muscle mRNA cytokine expression and protein content. Methods Twenty-four male runners (age 36.5u2009±u20091.8 years, VO2max 60.0u2009± 1.5u2009mL⋅kg−1u2009⋅u2009min−1) ran twice (separated by 4u2009weeks) on treadmills to exhaustion at 70% VO2max (average time and distance of 2.24u2009±u20090.09u2009h and 24.9u2009±u20091.1u2009km). Muscle biopsies from the vastus lateralis and blood samples were collected before and after each run, with IL-6, IL-8, and MCP-1 measured in muscle (mRNA and protein) and plasma. Data from the two runs were averaged. Results Participants experienced a 35.3u2009±u20094.2% decrease (Pu2009<u20090.001) in skeletal muscle glycogen content (67.5u2009±u20092.8 to 44.3u2009±u20093.7u2009mmol⋅kg−1 wet weight). Muscle mRNA expression for IL-6, IL-8, and MCP-1 increased 7.34u2009±u20090.90-, 13.9u2009±u20092.3-, and 4.10u2009±u20090.60-fold, respectively (all, Pu2009<u20090.001). Skeletal muscle IL-6, IL-8, and MCP-1 protein content increased 35.8u2009±u200910.6, 80.6u2009±u200912.1, and 105u2009±u200917.9%, respectively (all, Pu2009≤u20090.005). Plasma IL-6, IL-8, and MCP-1 increased 47.1u2009±u200910.0-, 2.6u2009±u20090.3-, and 1.6u2009±u20090.1-fold, respectively (all, Pu2009<u20090.001). Post-exercise muscle glycogen concentrations were negatively correlated with run time to exhaustion (ru2009=u2009−0.70, Pu2009<u20090.001), and changes in muscle IL-6 protein content (ru2009=u2009−0.44, Pu2009=u20090.049), plasma IL-6 (ru2009=u2009−0.72, Pu2009<u20090.001), IL-8 (ru2009=u2009−0.60, Pu2009=u20090.002), and MCP-1 (ru2009=u2009−0.589, Pu2009=u20090.002), but not with changes in muscle IL-8 and MCP-1 protein content, or muscle mRNA expression for IL-6, IL-8, and MCP-1. Conclusion Prolonged and intensive running increased muscle mRNA expression, muscle protein content, and plasma levels for IL-6, IL-8, and MCP-1, and post-run muscle glycogen levels were most strongly related to plasma cytokine levels.

Differential trafficking of saccharidic probes following aspirin in clinical tests of intestinal permeability in young healthy women

The effects of inflammatory changes on the absorption of different‐sized probes and their permeability ratios are poorly understood. The aim of the present study was to determine the effects of a pharmacological agent on the permeability of the gut mucosa to saccharidic probes of larger and smaller molecular weight. Permeability was assessed by half‐hourly urinary excretion of a combined dose of d‐mannitol, l‐rhamnose and lactulose following consumption of a single 600 mg dose of aspirin and compared with a placebo in a cross‐over study in 20 healthy female volunteers. The temporal patterns of excretion of all probes were bimodal, being best fitted by polynomial functions. The relatively small early peak was evident for at least 4 h for smaller sugars, but was less evident with lactulose, being overshadowed by a larger second peak. These conclusions were further supported by separate analyses of the segments of the temporal plots between 2.5 and 4 h and between 4.5 and 6 h. The forms of these curves did not change significantly following dosing with aspirin. A greater proportion of the total dose of mannitol than rhamnose was excreted over the collection period. Following the consumption of aspirin, the cumulative rate of excretion of the smaller sugars (i.e. mannitol and rhamnose) was significantly reduced whereas that of lactulose was increased over the 6 h collection period. Aspirin has opposite effects on the absorption of larger and smaller probes, influencing the outcome of the test. These results have important consequences for the design and comparison of clinical tests of permeability.