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Kochan, K.

Publications and source records attributed to Kochan, K..

2 recordsLinked to original sources

No change in oxytocin level before a human intergroup competition: study among Polish players before rugby and handball matches

ObjectivesThe aim of the present study was to assess the changes in urinary oxytocin concentration during the period between five days before, and on the day of match, among rugby and handball players. MethodsThe study used a repeated measures design with the relative oxytocin level as the outcome variable measured at two subsequent points of time, viz., on five days before as well as on the days of matches. Nine male rugby players with a mean age of 27.62 years (SD = 4.21) and 18 male handball players with a mean age of 17.03 years (SD = 0.57) participated. Urinary oxytocin level was measured by ELISA immunoassay as a ratio to the concentration of creatinine [mg/ml] measured through colorimetric detection. Differences in oxytocin level were assessed by ANOVA with repeated measurements. ResultsThe OT/CRE levels significantly differed between the type of player (rugby or handball) but not between times of measurements. Tukeys post-hoc tests revealed that significant differences were only between OT/CRE level in a day of match in rugby players and in 5 days before match in handball players (p<0.05). ConclusionThere was no change in oxytocin levels during the time periods between five days before and on the day of a match, in either of the two kinds of players. The change in oxytocin might be traceable during the match but not before a match and thus perhaps depends on a more subtle context of competition, but not on the assumption of competition.

evolutionary biology↗

Efficient long-range conduction in cable bacteria through nickel protein wires

Filamentous cable bacteria display unrivalled long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.

microbiology↗