Citrobacter freundii impairs the phosphoryl transfer network in the gills of Rhamdia quelen: Impairment of bioenergetics homeostasis.

The precise coupling of spatially separated intracellular adenosine triphosphate (ATP)-producing and ATP-consuming, catalyzed by creatine kinase (CK), adenylate kinase (AK), and pyruvate kinase (PK), is a critical process in the bioenergetics of tissues with high energy demand, such as the branchial tissue. The effects of Citrobacter freundii infection on gills remain poorly understood, limited only to histopathological studies. Thus, the aim of this study was to evaluate whether experimental infection by C. freundii impairs the enzymes of the phosphoryl transfer network in gills of silver catfish (Rhamdia quelen). The CK (cytosolic and mitochondrial) and AK activities decreased in infected compared to uninfected animals, while the PK activity did not differ between groups. The gill histopathology of infected animals revealed extensive degeneration with fusion and necrosis of secondary lamellae, detachment of superficial epithelium, aneurysm, vessel congestion and inflammatory process. Based on these evidences, the inhibition and absence of an efficient communication between CK compartments caused the impairment of the branchial bioenergetics homeostasis, which was not compensated by the augmentation on branchial AK activity in an attempt to restore energy homeostasis. In summary, these alterations contribute to disease pathogenesis linked to branchial tissue in animals infected with C. freundii.

Effect of side-stream smoking on random-pattern skin flap survival in rats.

The secondhand exposure to cigarette smoke is being considered evil, and damage caused by this passive exposure has been proven by several studies. To investigate the effects of sidestream smoke exposure on random-pattern skin flap survival, 20 female rats were separated into 2 groups: group A (n = 10) was exposed 6 weeks to the smoke from the burning cigarette (passive smoking) and group B (n = 10) was the control group. After 6 weeks of exposition, a dorsal McFarlane flap of 4 × 10 cm was performed in all rats. Two weeks after this procedure, the ratio of necrotic and total areas was calculated using computer programs. The median area of necrosis in group A was 29.5%, significantly higher than that in group B with 17.5% (P < 0.024). In conclusion, this study suggests increased risk of random-pattern skin flap necrosis after sidestream exposure to cigarette smoke.