The effect of caffeine, nap opportunity and their combination on biomarkers of muscle damage and antioxidant defence during repeated sprint exercise.

To investigate the effect of 20 min nap opportunity (N20), 5 mg · kg-1 of caffeine (CAF) and their combination (CAF+N20) on the biochemical response (energetic biomarkers, biomarkers of muscle damage and enzymatic antioxidants) to the running-based anaerobic sprint test. Fourteen highly trained male athletes completed in a double-blind, counterbalanced and randomized order four test sessions: no nap with placebo (PLA), N20, CAF and CAF+N20. Compared to PLA, all treatments enhanced maximum and mean powers. Minimum power was higher [(mean difference) 58.6 (95% confidence interval = 1.31-116) Watts] after CAF and [102 (29.9-175) Watts] after CAF+N20 compared to N20. Also, plasma glucose was higher after CAF [0.81 (0.18-1.45) mmol · l-1] and CAF+N20 [1.03 (0.39-1.64) mmol · l-1] compared to N20. However, plasma lactate was higher [1.64 (0.23-3.03) mmol · l-1] only after N20 compared to pre-exercise, suggesting a higher anaerobic glycolysis during N20 compared to PLA, CAF and CAF+N20. Caffeine ingestion increased post-exercise creatine kinase with [54.3 (16.7-91.1) IU · l-1] or without napping [58.9 (21.3-96.5) IU · l-1] compared to PLA. However, superoxide dismutase was higher after napping with [339 (123-554) U · gHB-1] or without caffeine [410 (195-625) U · gHB-1] compared to PLA. Probably because of the higher aerobic glycolysis contribution in energy synthesis, caffeine ingestion resulted in better repeated sprint performance during CAF and CAF+N20 sessions compared to N20 and PLA. Caffeine ingestion resulted in higher muscle damage, and the short nap enhanced antioxidant defence with or without caffeine ingestion.

Total Sleep Deprivation and Recovery Sleep Affect the Diurnal Variation of Agility Performance: The Gender Differences.

ABSTRACT: Romdhani, M, Hammouda, O, Smari, K, Chaabouni, Y, Mahdouani, K, Driss, T, and Souissi, N. Total sleep deprivation and recovery sleep affect the diurnal variation of agility performance: The gender differences. J Strength Cond Res 35(1): 132-140, 2021-This study aimed to investigate the effects of time-of-day, 24 and 36 hours of total sleep deprivation (TSD), and recovery sleep (RS) on repeated-agility performances. Twenty-two physical education students (11 male and 11 female students) completed 5 repeated modified agility T-test (RMAT) sessions (i.e., 2 after normal sleep night [NSN] [at 07:00 and 17:00 hours], 2 after TSD [at 07:00 hours, i.e., 24-hour TSD and at 17:00 hours, i.e., 36-hour TSD], and 1 after RS at 17:00 hours). The RMAT index decreased from the morning to the afternoon after NSN (p < 0.05, d = 1.05; p < 0.01, d = 0.73) and after TSD (p < 0.001, d = 0.92; d = 1.08), respectively, for total time (TT) and peak time (PT). This finding indicates a diurnal variation in repeated agility, which persisted after TSD. However, the diurnal increase in PT was less marked in the female group after NSN (2.98 vs. 6.24%). Moreover, TT and PT increased, respectively, after 24-hour TSD (p < 0.001; d = 0.84, d = 0.87) and 36-hour TSD (p < 0.001, d = 1.12; p < 0.01, d = 0.65). Female subjects' PT was less affected by 24-hour TSD (1.76 vs. 6.81%) compared with male subjects' PT. After 36-hour TSD, the amount of decrease was not different between groups, which increased the diurnal amplitude of PT only for male subjects. Total sleep deprivation suppressed the diurnal increase of PT and increased the diurnal amplitude of oral temperature only in women. Nevertheless, RS normalized the sleep-loss-induced performance disruption. Conclusively, sleep loss and RS differently affect repeated-agility performance of men and women during the day. Sleep extension postdeprivation could have potent restorative effect on repeated-agility performances, and female subjects could extract greater benefits.

The effect of post-lunch napping on mood, reaction time, and antioxidant defense during repeated sprint exercice.

To compare the effects of two nap opportunities (20 and 90 min) to countermeasure the transient naturally occurring increased sleepiness and decreased performances during the post-lunch dip (PLD). Fourteen highly trained judokas completed in a counterbalanced and randomized order three test sessions (control (No-nap), 20- (N20) and 90-min (N90) nap opportunities). Test sessions consisted of the running-based anaerobic sprint test (RAST), simple and multiple-choice reaction times (MCRT) and the Epworth sleepiness scale (ESS). From the RAST, the maximum (Pmax), mean (Pmean) and minimum (Pmin) powers were calculated. Blood samples were taken before and after the RAST to measure the effect of pre-exercise napping on energetic and muscle damage biomarkers and antioxidant defense. N20 increased Pmax and Pmean compared to No-nap (p < 0.001, d = 0.59; d = 0.66) and N90 (p < 0.001, d = 0.98; d = 0.72), respectively. Besides, plasma lactate and creatinine increased only when the exercise was performed after N20. Both N20 (p < 0.001, d = 1.18) and N90 (p < 0.01, d = 0.78) enhanced post-exercise superoxide dismutase activity compared to No-nap. However, only N20 enhanced post-exercise glutathione peroxidase activity (p < 0.001, d = 1.01) compared to pre-nap. Further, MCRT performance was higher after N20 compared to No-nap and N90 (p < 0.001, d = 1.15; d = 0.81, respectively). Subjective sleepiness was lower after N20 compared to No-nap (p < 0.05, d = 0.92) and N90 (p < 0.01, d = 0.89). The opportunity to nap for 20 min in the PLD enhanced RAST, MCRT performances, and antioxidant defense, and decreased sleepiness. However, the opportunity of 90 min nap was associated with decreased repeated sprint performances and increased sleepiness, probably because of the sleep inertia.

Sleep deprivation affects post-lunch dip performances, biomarkers of muscle damage and antioxidant status.

To compare the effects of two types of partial sleep deprivation (PSD) at the beginning (PSDBN) and the end (PSDEN) of the night on mood, cognitive performances, biomarkers of muscle damage, haematological status and antioxidant responses before and after repeated-sprint exercise in the post-lunch dip. Fourteen male athletes performed the Running-based Anaerobic Sprint Test following: (i) baseline normal sleep night, (ii) PSDBN, or (iii) PSDEN in a randomized and counter-balanced order. During each condition, participants performed simple and choice reaction time tests, the Profile of Mood States, subjective sleepiness, and the Running-based Anaerobic Sprint Test. Plasma biomarkers of muscle damage, total blood count, and antioxidant activities were measured at rest and after the repeated sprint in the three conditions. PSDEN decreased Pmax (p=0.008; d=1.12), Pmean (p=0.002; d=1.33) and Pmin (p=0.006; d=1.15), whilst PSDBN decreased Pmean (p=0.04; d=0.68) and Pmin (p=0.028; d=0.58), in comparison with baseline. PSDEN exerted stronger effects on Pmax (p=0.013; d=0.74) and Pmean (p=0.048; d=0.54) than PSDBN. Moreover, PSDEN increased subjective sleepiness (p<0.001; d=1.93), while PSDBN impaired choice reaction time (p<0.001, d=1.89). Both PSD types decreased resting glutathione peroxidase (p<0.001; d=5.43, d=3.86), and increased aspartate amino-transferase levels (p<0.001; d=1.36, d=1.37) respectively for PSDEN and PSDBN. PSDEN decreased repeated-sprint performances more than PSDBN in the post-lunch dip. This could be explained by the lowered mood and resting antioxidant status and the increased inflammatory profile after PSDEN. Repeated-sprint exercise resulted in greater inflammation after PSDEN, despite the decreased physical performance. The drop of resting antioxidant defence and haemoglobin concentration after PSDEN could explain the increased sleep drive at the post-lunch dip.

Use of extracellular polysaccharides, secreted by Lactobacillus plantarum and Bacillus spp., as reducing indole production agents to control biofilm formation and efflux pumps inhibitor in Escherichia coli.

The overuse of antibiotics and biofilm formation ability has led to the emergence of bacterial resistant strains. The combined use of several antibiotics has been found as an efficient strategy to overcome this resistance. In this study, two exopolysaccharides (EPS) obtained from Lactobacillus plantarum (EPS-Lp) and Bacillus spp. (EPS-B), isolated from a traditional Tunisian food "ricotta cheese" and hypersaline environment respectively, were used to counteract the biofilm formation and efflux pumps activities in Escherichia coli ATCC35218. The obtained results revealed that the tested EPSs can be effective against E. coli at a concentration > 1 mg/ml and were able to modulate biofilm formation by 50%. Moreover, at a concentration of 512 µg/ml, the tested EPSs inhibit the EtBr efflux in the tested bacteria and no significant difference was shown compared to cells treated with reserpine (P > 0.05). The positive effect of the tested EPSs may be due to the decrease of Indole production level proposed as a signal involved in quorum sensing and through the significant reduction of the hydrophobicity percentage between the treated and untreated cells. Overall, EPS-Lp and EPS-B, when used at appropriate concentration, may inhibit biofilm formation and reduce efflux pumps implicated in bacterial adhesion and antimicrobial resistance. These results make them an interesting candidate in the design of a new strategies to control bacterial biofilm-associated infections.

Motility, biofilm formation, apoptotic effect and virulence gene expression of atypical Salmonella Typhimurium outside and inside Caco-2 cells.

Disease outbreaks related to waterborne pathogen contamination throughout the world as well as challenges that lie ahead for addressing persistent infection are of renewed interest. In this research, we studied the effects of prolonged exposure of Salmonella enterica serovar Typhimurium to the cues encountered in the extracellular environment particularly in seawater microcosm on bacterial virulence and subsequent infection in Caco-2 cells. Our data show a significant difference in biofilm formation, swimming and swarming motilities between normal and stressed cells of S. Typhimurium under differing NaCl conditions (P < 0.05). Interestingly, adhesion, invasion and apoptotic activity to Caco-2 epithelial cells were determined during infection with normal and stressed Salmonella. Furthermore, we compared the expression of SPI-1 virulence genes (sopA, sopB, sopD, sopE2 and hilA) of normal and stressed S. Typhimurium in response to salt conditions encountered in the extracellular environment in LB broth and after epithelial cell exposure. The interest of the present study is due to the fact that to investigate the bacterial survival strategies during its movement from the natural surroundings to the host cell is fundamental to our understanding of the infection process during the host-pathogen interactions.

Use of carvacrol, thymol, and eugenol for biofilm eradication and resistance modifying susceptibility of Salmonella enterica serovar Typhimurium strains to nalidixic acid.

The Aims of the study was to evaluate the antibacterial susceptibility and the biofilm eradication of three natural compounds carvacrol (CAR), thymol (TH) and eugenol (EUG), alone or in combination with nalidixic acid (NA) against twelve Salmonella Typhimurium strains. The minimum inhibitory concentration (MIC) and the minimum biofilm eradication concentration (BEC50) of the tested compounds (CAR, TH and EUG) and their combinations with NA were evaluated. In order to assess whether these bacteria had active efflux pumps, ethidium bromide (EtBr) accumulation assays was achieved using spectrophotometric accumulation assays. Moreover, scanning electron microscopy was used to visualize the bacterial biofilm formation on stainless steel surfaces after exposed to NA, CAR, TH and EUG alone and in combination. TH was the most effective essential oil, with the lowest MICs values ranging from 32 to 128 µg/mL followed by EUG and CAR. In addition, the combination of NA with the different compounds enhances antibiotic susceptibility of the tested bacterial strains. These results were confirmed by EtBr accumulation assays. A pronounced effect in decreasing biofilm mass was also noticed. Moreover, SEM revealed that bacterial membrane was disrupted and a complete loss of membrane integrity was also evident. The combination of natural compounds with antibiotic enhances bacterial susceptibility to NA. This combination ameliorates eradication of biofilm formed by S. Typhimurium on polystyrene microtitre plates. Additionally, this synergy induces an alteration of the bacterial cell surface visualized by SEM.

Adhesion, invasion, cytotoxic effect and cytokine production in response to atypical Salmonella Typhimurium infection.

Pathogenic bacteria such as Salmonella have the ability to respond to a wide variety of environmental stimuli. These responses allow them to survive and withstand insults both of an external location as well as within the host. The aim of this study was to investigate the effect of preadaptation in stressful conditions encountered in seawater microcosms for different periods of time on Salmonella Typhimurium survival, antibiotic susceptibility and interactions with Caco-2 cells. These results showed that the number of bacterial cells depends from the periods of stress in culture medium, highlighting the importance of using the right culture medium for the enumeration of stressed bacteria. The antibiotic resistance of starved cells was modified and their exposure to stressful conditions in seawater during 12 months significantly increased adhesion, invasion and cytotoxic activities on Caco-2 cells. Moreover, cellular cytokines IL-6 and IL-8 secretions were up-regulated. Present results seem to suggest that the preadaptation of S. Typhimurium in seawater microcosms affect the cultural characters by the appearance of the atypical cells that may play a critical role in the intestinal infection and in the systemic spread of the disease. These findings are very important to understand bacterial responses to changing conditions and explain the persistence of these atypical in eukaryotic cells.

Extracellular polysaccharide derived from potential probiotic strain with antioxidant and antibacterial activities as a prebiotic agent to control pathogenic bacterial biofilm formation.

Because of their functional diversity, bioactive compounds are becoming a new biocontrol agent to limit biofilm formation by pathogens. In this study, the physico-chemical characterization of an exopolysaccharide (EPS) isolated from Lactobacillus plantarum (EPLB) was characterized and its in vitro effect on biofilm formation was studied. The EPS had a molecular weight of 36 kDa and polydispersity index estimated to be 1.2. The tested EPLB had an antibacterial activity, with a Minimal Inhibition Concentration (MIC) values ranging between 1 mg/ml and 10 mg/ml, displayed an antibiofilm effect concentration dependent on Gram positive and negative strains. Among the pathogenic strains, 2 out of 4 appeared to be more than 50% inhibited in their biofilm development by the EPS. The antibiofilm activity can be due to the ability of the EPS to influence the function of biological membranes like hydrophobicity that decreased (P < 0.05) when the EPS was used at a concentration of 512 µg/ml. This EPS without cytotoxic effect, showed an antioxidant effect on the quenching of DPPH radicals and the inhibition of lipid peroxidation with a percentage of 64% and 66%, respectively. Taken together these biological properties, EPLB can be considered as a potential prebiotic agent in the design of new therapeutic strategies for bacterial biofilm-associated infections.

Synergistic effect of eugenol, carvacrol, thymol, p-cymene and γ-terpinene on inhibition of drug resistance and biofilm formation of oral bacteria.

Dental caries remains the most prevalent oral infectious disease worldwide. In this study, the antibacterial and the antibiofilm activities of five essential oils (EO's): eugenol (EUG), carvacrol (CAR), thymol (TYH), p-cymene (CYM) and γ-terpinene (TER) were tested (alone or in combinaison with tetracycline) against oral bacteria. In addition, their potential roles to enhance the accumulation of ethidium bromide (EtBr) in bacterial cells were tested. Our results indicated that EO's induced a selective antimicrobial activity. A synergistic effect of EO's and tetracycline (TET) was noticed with a reduction rate ranged from 2 to 8-fold. In addition, the efflux of EtBr was inhibited with a decrease in loss of EtBr from the bacteria. On the other hand a significant anti-biofilm activities of EO's (alone or combined with antibiotics) was noticed. In conclusion the tested EO's may be considered as a potential natural source with a resistance-modifying activity and may be applied to eradicate bacterial biofilm.