Antibacterial Properties and Potential Mechanism of Serum from Chinese Alligator.

The Chinese alligator (Alligator sinensis) is an ancient reptile with strong immunity that lives in wetland environments. This study tested the antibacterial ability of Chinese alligator serum (CAS) against Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa and analyzed the potential underlying mechanisms. Results showed that the CAS had a marked antibacterial effect on K. pneumoniae, E. coli, and P. aeruginosa, while S. aureus was only mildly affected. However, these effects disappeared when Protease K was added to the serum. The serum proteome analysis revealed that the antibacterial ability of CAS was produced by interactions among various proteins and that the complement proteins played a major antibacterial role. Therefore, we made relevant predictions about the structure and function of complement component 3. In addition, sequence alignment and phylogenetic analysis of complement component 3d (C3d) in four mammalian species and two alligator species showed that the amino acids that make up the acid pocket on the concave surface of alligator C3d are not identical to those in mammals. This study provided evidence that CAS elicits significant antibacterial effects against some pathogens and provides the basis for further development of novel antibacterial drugs.

Effect of active arm swing to local dynamic stability during walking.

Arm swing is an essential component in regulating dynamic stability of the whole body during walking, while the contribution of active arm swing to local dynamic stability of different motion segments remains unclear. This study investigated the effects of arm swing under natural arm swing condition and active arm swing condition on local dynamic stability and gait variability of the trunk segments (C7 and T10 joint) and lower extremity joints (hip, knee and ankle joint). The local divergence exponents (λs) and mean standard deviation over strides (MeanSD) of 24 young healthy adults were calculated while they were walking on treadmill with two arm swing conditions at their preferred walking speed (PWS). We found that in medial-lateral direction, both λs and MeanSD values of the trunk segments (C7 and T10 joint) in active arm swing condition were significantly lower than those in natural arm swing condition (p<0.05), while no significant difference of λs or MeanSD in lower extremity joints (hip, knee and ankle joint) was found between two arm swing conditions (p>0.05, respectively). In anterior-posterior and vertical direction, neither λs nor MeanSD values of all body segments showed significant difference between two arm swing conditions (p>0.05, respectively). These findings indicate that active arm swing may help to improve the local dynamic stability of the trunk segments in medial-lateral direction.

Kinematic characteristics of gait in middle-aged adults during level walking.

Middle-aged people have shown a high fall incidence and degeneration in gait stability, while few studies concern that. This study aimed to assess the kinematic characteristics of gait in middle-aged people compared with younger and older ones during level walking, and to find sensitive indicators to characterize degenerated gait stability in middle-aged people. 13 middle-aged (mean age=52.1 years), with 13 older (mean age=74.8 years) and 13 young (mean age=23.3 years) healthy adults participated in this study. We assessed following gait parameters of the subjects during their level walking: 1) temporal-spatial gait parameters: normalized gait velocity, stride length, step length and their variability; 2) gait stability parameters: acceleration root mean square (RMS) of COM and its variability; and instantaneous COM-COP inclination angles. Compared with young and older subjects, middle-aged adults showed no significant difference in temporal-spatial gait parameters and their stride-to-stride variability (P>0.050); Compared with young subjects, middle-aged adults showed a significant higher value in medial-lateral (ML) direction of acceleration RMS of COM (P=0.038) and its stride-to-stride variability (P=0.030), as well as in COM-COP inclination angle (P=0.003). There was no significant difference in the above two parameters of gait stability between middle-aged and older subjects (P>0.050). Results illustrated that middle-aged subjects showed similar degenerated pattern in gait stability as the older ones in ML direction. Gait stability parameters, including ML acceleration of COM and its variability, as well as ML COM-COP inclination angle may help to characterize this degenerated gait stability. It's necessary for us to develop early interventions for middle-aged adults to prevent falls during walking.