Plyometric exercise increases serum indices of muscle damage and collagen breakdown

The aim of the present study was to examine the effect of acute plyometric exercise on indices of muscle damage and collagen breakdown. Nine untrained men performed an intense bout of plyometric jumping exercises (experimental group) and nine men remained at rest (control group). Seven days before and 24, 48, and 72 hours after plyometric exercise or rest, several physiological and biochemical indices of muscle damage and two biochemical indices of collagen damage were determined. No significant changes in concentric and eccentric peak torque of knee extensors and flexors or flexion and extension range of motion were found after the plyometric exercise. Delayed-onset muscle soreness increased 48 hours after exercise. Creatine kinase increased 48 and 72 hours post exercise, whereas lactate dehydrogenase increased 24, 48, and 72 hours post exercise. Serum hydroxyproline increased 24 hours post exercise, peaked at 48 hours, and remained elevated up to 72 hours post exercise. Hydroxylysine (which was measured only before exercise and at 48 hours) was found increased 48 hours post exercise. No differences were found in any physiological or biochemical index in the control group. Intense plyometric exercise increased muscle damage, delayed-onset muscle soreness, and serum indices of collagen breakdown without a concomitant decrease in the functional capacity of muscles. Hydroxyproline and hydroxylysine levels in serum seem promising measures for describing exercise-induced collagen degradation. Coaches need to keep in mind that by using plyometric activities, despite the increased muscle damage and collagen turnover that follow, it is not necessarily accompanied by decreases in skeletal muscle capacity.     

The iron-sulfur center of biotin synthase: site-directed mutants

Biotin synthase contains an essential [4Fe-4S]+ cluster that is thought to provide an electron for the cleavage of S-adenosylmethionine, a cofactor required for biotin formation. The conserved cysteine residues Cys53, Cys57 and Cys60 have been proposed as ligands to the [4Fe-4S] cluster. These residues belong to a C-X3-C-X2-C motif which is also found in pyruvate formate lyase-activating enzyme, lysine 2,3-aminomutase and the anaerobic ribonucleotide reductase-activating component. To investigate the role of the cysteine residues, Cys-->Ala mutants of the eight cysteine residues of Escherichia coli biotin synthase were prepared and assayed for activity. Our results show that six cysteines are important for biotin formation. Only two mutant proteins, C276A and C288A, closely resembled the wild-type protein, indicating that the corresponding cysteines are not involved in iron chelation and biotin formation. The six other mutant proteins, C53A, C57A, C60A, C97A, C128A and C188A, were inactive but capable of assembling a [4Fe-4S] cluster, as shown by M?ssbauer spectroscopy. The C53A, C57A and C60A mutant proteins are unique in that their cluster could not undergo reduction to the [4Fe-4S]+ state, as shown by EPR and M?ssbauer spectroscopy. On this basis and by analogy with pyruvate formate lyase-activating enzyme and the anaerobic ribonucleotide reductase-activating component, it is suggested that the corresponding cysteines coordinate the cluster even though one cannot fully exclude the possibility that other cysteines play that role as well. Therefore it appears that for activity biotin synthase absolutely requires cysteines that are not involved in iron chelation.     

Instruments to Assess Secondhand Smoke Exposure in Large Cohorts of Never Smokers: The Smoke Scales

The objectives of this study were to: (i) to develop questionnaires that can identify never-smoking children and adults experiencing increased exposure to secondhand smoke (SHS+), (ii) to determine their validity against hair nicotine, and (iii) assess their reliability. A sample of 191 children (85 males; 106 females; 7–18 years) and 95 adult (23 males; 72 females; 18–62 years) never-smokers consented to hair nicotine analysis and answered a large number of questions assessing all sources of SHS. A randomly-selected 30% answered the questions again after 20–30 days. Prevalence of SHS+ in children and adults was 0.52±0.07 and 0.67±0.10, respectively (p<0.05). The Smoke Scale for Children (SS-C) and the Smoke Scale for Adults (SS-A) were developed via factor analysis and included nine questions each. Positivity criteria for SS-C and SS-A via receiver operating characteristics curve analysis were identified at >16.5 and >16, respectively. Significant Kappa agreement (p<0.05) was confirmed when comparing the SS-C and SS-A to hair nicotine concentration. Reliability analyses demonstrated that the SS-C and SS-A scores obtained on two different days are highly correlated (p<0.001) and not significantly different (p>0.05). Area under the curve and McNemar''s Chi-square showed no pair-wise differences in sensitivity and specificity at the cutoff point between the two different days for SS-C and SS-A (p>0.05). We conclude that the SS-C and the SS-A represent valid, reliable, practical, and inexpensive instruments to identify children and adult never-smokers exposed to increased SHS. Future research should aim to further increase the validity of the two questionnaires.     

Exploring the Efficacy of Endoscopic Ventriculostomy for Hydrocephalus Treatment via a Multicompartmental Poroelastic Model of CSF Transport: A Computational Perspective

This study proposes the implementation of a Multiple-Network Poroelastic Theory (MPET) model coupled with finite-volume computational fluid dynamics for the purpose of studying, in detail, the effects of obstructing CSF transport within an anatomically accurate cerebral environment. The MPET representation allows the investigation of fluid transport between CSF, brain parenchyma and cerebral blood, in an integral and comprehensive manner. A key novelty in the model is the amalgamation of anatomically accurate choroid plexuses with their feeding arteries and a simple relationship relaxing the constraint of a unique permeability for the CSF compartment. This was done in order to account for the Aquaporin-4-mediated swelling characteristics. The aim of this varying permeability compartment was to bring to light a feedback mechanism that could counteract the effects of ventricular dilation and subsequent elevations of CSF pressure through the efflux of excess CSF into the blood system. This model is used to demonstrate the impact of aqueductal stenosis and fourth ventricle outlet obstruction (FVOO). The implications of treating such a clinical condition with the aid of endoscopic third (ETV) and endoscopic fourth (EFV) ventriculostomy are considered. We observed peak CSF velocities in the aqueduct of the order of 15.6 cm/s in the healthy case, 45.4 cm/s and 72.8 cm/s for the mild and severe cases respectively. The application of ETV reduced the aqueductal velocity to levels around 16–17 cm/s. Ventricular displacement, CSF pressure, wall shear stress (WSS) and pressure difference between lateral and fourth ventricles (ΔP) increased with applied stenosis, and subsequently dropped to nominal levels with the application of ETV. The greatest reversal of the effects of atresia come by opting for ETV rather than the more complicated procedure of EFV.     

Novel synthetic RGD analogs incorporating salicylic acid derivatives show antiplatelet activity in vitro

Continuing our investigational efforts for more active GpIIb/IIIa inhibitors we have synthesized four novel RGD (Arg-Gly-Asp) analogs incorporating salicylic acid derivatives at their N-terminal amino group using the solid phase synthesis.The synthesized compounds 5-Cl-2-HO-C₆H₃-CO-Arg-Gly-Asp(OBzl)-NH₂and 5-Br-2-HO-C₆H₃-CO-Arg-Gly-Asp(OBzl)-NH₂ were tested for their inhibitory activity on human platelet aggregationin vitro and found to be potent inhibitors of the platelet aggregation with 75 and 67% inhibitory activity respectively. In order to confirm our results flow cytometry with monoclonal antibodies against GpIb, GpIIb/IIIa, GpIIIa and GMP140receptors was used.     

Inhibition of the Early Stage of Salmonella enterica Serovar Enteritidis Biofilm Development on Stainless Steel by Cell-Free Supernatant of a Hafnia alvei Culture

Compounds present in Hafnia alvei cell-free culture supernatant cumulatively negatively influence the early stage of biofilm development by Salmonella enterica serovar Enteritidis on stainless steel while they also reduce the overall metabolic activity of S. Enteritidis planktonic cells. Although acylhomoserine lactones (AHLs) were detected among these compounds, the use of several synthetic AHLs was not able to affect the initial stage of biofilm formation by this pathogen.Biofilms are groups of bacteria encased in a self-produced extracellular matrix (5, 6). Biofilms formed on stainless steel (SS) surfaces in food-processing areas are of great importance since they may lead to food spoilage and transmission of diseases (2, 16). This sessile mode of life allows bacteria to enjoy a number of advantages, such as increased resistance to antimicrobial agents (9, 12). Notably, it is widely accepted that bacteria (both planktonic and biofilm cells) communicate by releasing and sensing signaling compounds in a process commonly known as quorum sensing (13, 18, 24).Salmonella enterica serovar Enteritidis is one of the most important bacterial pathogens worldwide (7, 17). Hafnia alvei are frequent psychrotrophic members of the Enterobacteriaceae community in meat products, playing a role in their spoilage, while they have been shown to be capable of producing signaling compounds (3). In this study, in order to determine any possible influence of compounds produced by H. alvei on the biofilm-forming ability of S. Enteritidis, the latter was left to develop biofilm on SS surfaces in the presence of conditioned medium obtained after the growth of the former. Biofilm formation was assessed directly by detaching cells and enumerating them and, also, indirectly by automated conductance measurements.     

Analysis of fast chlorophyll fluorescence rise (O‐K‐J‐I‐P) curves in green fruits indicates electron flow limitations at the donor side of PSII and the acceptor sides of both photosystems

Limited evidence up to now indicates low linear photosynthetic electron flow and CO₂ assimilation rates in non‐foliar chloroplasts. In this investigation, we used chlorophyll fluorescence techniques to locate possible limiting steps in photosystem function in exposed, non‐stressed green fruits (both pericarps and seeds) of three species, while corresponding leaves served as controls. Compared with leaves, fruit photosynthesis was characterized by less photon trapping and less quantum yields of electron flow, while the non‐photochemical quenching was higher and potentially linked to enhanced carotenoid/chlorophyll ratios. Analysis of fast chlorophyll fluorescence rise curves revealed possible limitations both in the donor (oxygen evolving complex) and the acceptor (Q_A^?→ intermediate carriers) sides of photosystem II (PSII) indicating innately low PSII photochemical activity. On the other hand, PSI was characterized by faster reduction of its final electron acceptors and their small pool sizes. We argue that the fast reductive saturation of final PSI electron acceptors may divert electrons back to intermediate carriers facilitating a cyclic flow around PSI, while the partial inactivation of linear flow precludes strong reduction of plastoquinone. As such, the photosynthetic attributes of fruit chloroplasts may act to replenish the ATP lost because of hypoxia usually encountered in sink organs with high diffusive resistance to gas exchange.     

Molecular dynamics investigation of the influence of anionic and zwitterionic interfaces on antimicrobial peptides' structure: implications for peptide toxicity and activity

Molecular dynamics simulations of three related helical antimicrobial peptides have been carried out in zwitterionic diphosphocholine (DPC) micelles and anionic sodiumdodecylsulfate (SDS) micelles. These systems can be considered as model mammalian and bacterial membrane interfaces, respectively. The goal of this study is to dissect the differences in peptide composition which make the mutant peptides (novispirin-G10 and novispirin-T7) less toxic than the parent peptide ovispirin (OVIS), although all three peptides have highly antibacterial properties. Compared to G10 and T7, OVIS inserts deepest into the DPC micelle. This correlates well with the lesser toxicity of G10 and T7. There is strong evidence which suggests that synergistic binding of hydrophobic residues drives binding of OVIS to the micelle. The helical content of G10 and T7 is reduced in the presence of DPC, and this leads to less amphipathic peptide structures, which bind weakly to the micelle. Simulations in SDS were carried out to compare the influence of membrane electrostatics on peptide structure. All three peptides bound strongly to SDS, and retained helical form. This corresponds well with their equally potent antibacterial properties. Based on the simulations, we argue that secondary structure stability often leads to toxic properties. We also propose that G10 and T7 operate by the carpet mechanism of cell lysis. Toxicity of peptides operating by the carpet mechanism can be attenuated by reducing the peptide helical content. The simulations successfully capture experimental binding states, and the different depths of binding of the three peptides to the two micelles correlate with their antibacterial and toxic properties.     

Mesophyll versus epidermal anthocyanins as potential in vivo antioxidants: evidence linking the putative antioxidant role to the proximity of oxy-radical source

The hypothesis that anthocyanins in red leaves may be potential in vivo antioxidants whose efficiency is linked to their proximity with the oxy-radical source was tested. Advantage was taken of intra-individual and intra-species variations in the anthocyanic trait and green and red leaves on the same individuals or leaves of green and red phenotypes were compared for the extent of PSII damage by reactive oxygen species generated by methyl viologen treatment in the light. Two species possessing anthocyanins in the mesophyll (Cistus creticus and Photinia x fraseri) and two in the epidermis (Rosa sp. and Ricinus communis) were used, while red actinic light (which is not absorbed by anthocyanins) allowed discrimination between an indirect sunscreen and a direct antioxidant function. Red leaves whose anthocyanins were located in the mesophyll were more resistant to methyl viologen treatment than their green counterparts. In one of these species (Cistus creticus), where anthocyanins are induced in some individuals within the natural population after bright cool days in winter, both green and future-red morphs displayed the same sensitivity to methyl viologen before anthocyanin induction. Immediately after reddening, however, resistance to methyl viologen was considerably increased in the red morphs. By contrast, red leaves whose anthocyanins were restricted to epidermal cells were more sensitive to the herbicide. Total leaf phenolic levels in green/red pairs were similar. The results indicate that vacuolar anthocyanins may be an effective in vivo target for oxy-radicals, provided that the oxy-radical source and the anthocyanic detoxifying sink are in close vicinity.