Spatiotemporal dynamics of the social structure of Indo-Pacific humpback dolphins ( Sousa chinensis) in Xiamen waters from 2007 to 2019.

As highly social animals, Indo-Pacific humpback dolphins ( Sousa chinensis) exhibit community differentiation. Nevertheless, our understanding of the external and internal factors influencing these dynamics, as well as their spatiotemporal variations, is still limited. In the present study, variations in the social structure of an endangered Indo-Pacific humpback dolphin population in Xiamen Bay, China, were monitored over two distinct periods (2007-2010 and 2017-2019) to analyze the effects of habitat utilization and the composition of individuals within the population. In both periods, the population demonstrated a strikingly similar pattern of social differentiation, characterized by the division of individuals into two main clusters and one small cluster. Spatially, the two primary clusters occupied the eastern and western waters, respectively, although the core distribution area of the eastern cluster shifted further eastward between the two periods. Despite this distribution shift, the temporal stability of the social structure and inter-associations within the eastern cluster remained unaffected. A subset of 16 individuals observed in both periods, comprising 51.6% and 43.2% of the population in each respective period, emerged as a foundational element of the social structure and may be responsible for sustaining social structure stability, especially during the 2007-2010 period. These observations suggest that the composition of dominant individuals, an internal factor, had a more substantial influence on the formation of the social network than changes in habitat use, an external factor. Consequently, the study proposes distinct conservation measures tailored to each of the two main clusters.

Study of transpedicular screw fixation on spine development in a piglet model.

BACKGROUND: Transpedicular screws may cause damage to the cartilage in the neural arch of the vertebra, and give continuous pressure to the skeleton besides the vertebral body. The aim of this study is to examine the morphological change of the vertebral body at fixation sites and development of the vertebral body after fixation. METHODS: A piglet model was used to study the influence of transpedicular screw fixation on spine development. Transpedicular screw fixation was adjusted to meet specific requirements of surgery on piglet. The screws and plates were placed at L1-L3 vertebral plates via routine surgical approach. Scoliosis and kyphosis Cobb angles were measured. RESULTS: Anatomical characteristics of 6-week-old piglets fit the transpedicular screw system, and can meet the requirements of related studies. Transpedicular screw fixation system has no significant influence on the development of canalis vertebralis. Fixation did not cause developmental stenosis of canalis vertebralis and damage to spinal cord or nerve root. However, transpedicular screw fixation significantly impacted the development of the spine: it shortened the spine by curtailing the length of the vertebral body and intervertebral space. Our results also suggested that slow growth of epiphyseal plate may contribute to the shortening of the vertebral body. CONCLUSION: Transpedicular screw fixation system is beneficial for fixation of the developing spine. It may not cause scoliosis but could lead to change of cervical curvature.

[Measurement of diameter of T4 pedicle-rib compomers].

OBJECTIVE: To measure the diameter of T4 pedicle-rib compomers in normal human spines and discuss the importance of related dates. METHODS: T4 computerized tomography (CT) images,including two-dimensional,three-dimensional reconstruction, of 12 random adult patients were harvested. There were 7 males and 5 females with a mean age of 23 years (ranged, 19 to 28 years). The patients were divided into groups by self control,which means the diameter of pedicle compared with that of pedicle-rib unit in the same side of each T4. The facility was GE light speed 16. Measurement of the body specimens from T3 to T5 . The parameter included the width of pedicle-rib unit compared with pedicle,the longitudinal diameter of pedicle-rib unit compared with pedicle, especially for the pedicle-rib overlap. RESULTS: The relationship of T4 pedicle and rib were not on the same level but overlapping. The width of pedicle-rib unit was significantly larger than that of pedicle (P<0.05). The longitudinal diameters of pedicle-rib unit or pedicle were significantly larger than those of pedicle-rib overlap (P<0.05); while there was no significantly difference between the pedicle-rib unit and pedicle (P>0.05). CONCLUSION: The overlapping relationship of T4 pedicle and rib is partly but not whole, which means the longitudinal diameter of T4 pedicle-rib overlap should not be considered as the same of unit or pedicle.

[The anatomic and radiographic morphometry of thoracic pedicle rib unit].

OBJECTIVES: To investigate the spatial structure of pedicle rib units in normal thoracic human spines and to compare the dimensions of the pedicle rib unit with corresponding dimensions. METHODS: Thoracic spine specimens in four fresh adult cadaveric were used. Computerized tomographic (CT) images (including two-dimensional, three-dimensional reconstruction) of the thoracic spines were obtained. Measurement parameters include:the width, the height, the chord length and the sagittal angles of the pedicle rib unit compared with pedicle, especially for the pedicle-rib overlapping height. RESULTS: The pedicle rib unit was not a simple two-dimensional structure but a three-dimensional structure. The shortest height of pedicle rib unit was (12.6 ± 0.8) mm (T(1)), while the longest was (16.9 ± 1.1) mm (T(11)). The shortest height of pedicle-rib overlap was (7.2 ± 0.3) mm (T(1)), while the longest was (11.8 ± 1.0) mm (T(10)). The height of pedicle rib unit and the height of pedicle were significantly larger than that of the pedicle-rib overlap (P < 0.05), while there was no significantly difference between the height of pedicle rib unit and the height of pedicle (P > 0.05). CONCLUSIONS: The pedicle rib unit is a complicated spatial structure, and the longitudinal height of pedicle-rib overlap should be taken as the real height of the unit.

Spontaneous recovery of locomotion induced by remaining fibers after spinal cord transection in adult rats.

PURPOSE: A major issue in analysis of experimental results after spinal cord injury is spontaneous functional recovery induced by remaining nerve fibers. The authors investigated the relationship between the degree of locomotor recovery and the percentage and location of the fibers that spared spinal cord transection. METHODS: The spinal cords of 12 adult rats were transected at T9 with a razor blade, which often resulted in sparing of nerve fibers in the ventral spinal cord. The incompletely-transected animals were used to study the degree of spontaneous recovery of hindlimb locomotion, evaluated with the BBB rating scale, in correlation to the extent and location of the remaining fibers. RESULTS: Incomplete transection was found in the ventral spinal cord in 42% of the animals. The degree of locomotor recovery was highly correlated with the percentage of the remaining fibers in the ventral and ventrolateral funiculi. In one of the rats, 4.82% of remaining fibers in unilateral ventrolateral funiculus were able to sustain a certain recovery of locomotion. CONCLUSIONS: Less than 5% of remaining ventrolateral white matter is sufficient for an unequivocal motor recovery after incomplete spinal cord injury. Therefore, for studies with spinal cord transection, the completeness of sectioning should be carefully checked before any conclusion can be reached. The fact that the degree of locomotor recovery is correlated with the percentage of remaining fibers in the ventrolateral spinal cord, exclusive of most of the descending motor tracts, may imply an essential role of propriospinal connections in the initiation of spontaneous locomotor recovery.