A novel growth-promoting pathway formed by GDNF-overexpressing Schwann cells promotes propriospinal axonal regeneration, synapse formation, and partial recovery of function after spinal cord injury.

Descending propriospinal neurons (DPSN) are known to establish functional relays for supraspinal signals, and they display a greater growth response after injury than do the long projecting axons. However, their regenerative response is still deficient due to their failure to depart from growth supportive cellular transplants back into the host spinal cord, which contains numerous impediments to axon growth. Here we report the construction of a continuous growth-promoting pathway in adult rats, formed by grafted Schwann cells overexpressing glial cell line-derived neurotrophic factor (GDNF). We demonstrate that such a growth-promoting pathway, extending from the axonal cut ends to the site of innervation in the distal spinal cord, promoted regeneration of DPSN axons through and beyond the lesion gap of a spinal cord hemisection. Within the distal host spinal cord, regenerated DPSN axons formed synapses with host neurons leading to the restoration of action potentials and partial recovery of function.

[Three-dimensional finite element analysis of three-material endocrown in the restoration of dental defects of mandibular second molars].

PURPOSE: To analyse the effect of restoration and tooth tissue stress distribution under different occlusal preparation thickness, based on three-dimensional finite element modal of the mandibular second molar with root canal therapy and endocrown restorations. METHODS: A mandibular second molar was scanned by cone-beam CT (CBCT) and a three-dimensional finite element model with endocrown restortions was established． Three kinds of endocrown restorations materials with different elastic modulus (glass ceramic, lithium disilicate ceramic and zirconia), and three types of occluscal thickness (1, 2 and 3 mm) were adopted. With a 200 N force loaded vertically and obliquely, the distribution and magnitude of stress in the tooth tissue and endocrown restorations were investigated by three-dimensional finite element analysis． RESULTS: The restoration and tooth tissue maximum stress values were increased firstly and then decreased with the increasing of occlusal thickness; the base material maximum stress values were decreased with the increasing of occlusal thickness; the maximum stress values of tooth tissue and base material were increased with the increasing of restoration material's Young's modulus. Compared to the loading in vertical direction, the maximum stress values were increased with loading in oblique direction. CONCLUSIONS: It's beneficial for tooth tissue to reduce the stress concentration under 2mm thickness. The stress on endocrown will be more concentrated with the increasing of restoration material's Young's modulus.

[Effect of special oral care mode on periodontal health in adolescent orthodontic patients].

PURPOSE: To investigate the effect of special oral care mode on periodontal health of adolescent orthodontic patients. METHODS: From January 2019 to January 2020, one hundred adolescent orthodontic patients who received treatment in our hospital were randomly divided into experimental group and control group according to the principle of completely random number table, with 50 cases in each group. Patients in the control group were given routine oral care, while those in the experimental group were given special oral care; three months later, the periodontal health status of the two groups were compared using SPSS 21.0 software package. RESULTS: There was no significant difference in PLI and GI between the two groups before treatment (P＞0.05). After treatment, PLI and GI in the experimental group were significantly lower than those in the control group(P＜0.01). There was no significance difference in SBI and EDI before treatment between the two groups(P＞0.05). After treatment, SBI and EDI in the experimental group were significantly lower than those in the control group(P＜0.01). There was no significant difference in the scores of periodontal health knowledge before treatment between the two groups(P＞0.05). After treatment, the scores of the two groups were significantly increased(P＜0.01), and the scores of the experimental group were significantly higher than those of the control group (P＜0.01). The patients' satisfaction in the experimental group was significantly higher than that in the control group (90.00% vs 72.00%, P=0.022). CONCLUSIONS: Special oral care mode can significantly improve periodontal health status of adolescent orthodontic patients.

Transhemispheric cortex remodeling promotes forelimb recovery after spinal cord injury.

Understanding the reorganization of neural circuits spared after spinal cord injury in the motor cortex and spinal cord would provide insights for developing therapeutics. Using optogenetic mapping, we demonstrated a transhemispheric recruitment of neural circuits in the contralateral cortical M1/M2 area to improve the impaired forelimb function after a cervical 5 right-sided hemisection in mice, a model mimicking the human Brown-Séquard syndrome. This cortical reorganization can be elicited by a selective cortical optogenetic neuromodulation paradigm. Areas of whisker, jaw, and neck, together with the rostral forelimb area, on the motor cortex ipsilateral to the lesion were engaged to control the ipsilesional forelimb in both stimulation and nonstimulation groups 8 weeks following injury. However, significant functional benefits were only seen in the stimulation group. Using anterograde tracing, we further revealed a robust sprouting of the intact corticospinal tract in the spinal cord of those animals receiving optogenetic stimulation. The intraspinal corticospinal axonal sprouting correlated with the forelimb functional recovery. Thus, specific neuromodulation of the cortical neural circuits induced massive neural reorganization both in the motor cortex and spinal cord, constructing an alternative motor pathway in restoring impaired forelimb function.

Multidecadal records of microplastic accumulation in the coastal sediments of the East China Sea.

Microplastics are an emerging hazard in the marine environment, and considered to eventually sink into sediments. An investigation into the long-term variation of microplastic accumulation in sediment cores is essential for understanding the historical trend of this contamination and its response to human activities. In this study, the multidecadal changes of microplastic abundances in two sediment cores from the inner shelf of the East China Sea (ECS) were revealed by two methods, i.e., a visual enumeration method based on scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and a quantitative method based on microplastic-derived carbon (MPC) abundances. The features of microplastics were determined via SEM-EDS and micro-Fourier transform infrared spectroscopy (µ-FTIR). The results reveal a multidecadal increasing trend of microplastic accumulation in the coastal sediments of the ECS since the 1960s, which may be jointly governed by the release of plastic wastes and oceanographic dynamics. Meanwhile, the breakpoint of the exponential growth of microplastics in the ECS occurs in 2000 AD, which well matches the rapid increasing of plastic production and consumption in China. Further, based on the MPC contents in sediments, the influence of microplastics on the quantitative evaluation of carbon storage in the ECS has been examined for the first time, revealing an insignificant (<2% before 2014 AD) but potentially-increasing (6.8% by 2025 AD) contribution of microplastics to carbon burial. Our results may provide the important data for evaluating and mitigating the impact of microplastics on the marine environment.

[Application of spiral CT reconstruction in the forensic identification of atlantoaxial injuries].

OBJECTIVE: To evaluate diagnostic value of spiral CT reconstruction in atlantoaxial injuries. METHODS: The images of 25 cases of spiral CT reconstruction were analyzed and compared with images of CT scan and X-ray. RESULTS: In 7 cases of odontoid process fracture, X-ray demonstrated 4 cases and CT demonstrated 5 cases, whereas the spiral CT reconstruction diagnosed 7 cases, which could display the displacement of fracture clearly. The X-ray and CT showed asymmetric space between left and right gaps of atlantoaxial joint in 6 cases, while spiral CT reconstruction showed normal and excluded the possibility of atlantoaxial dislocation. There was one case of lateral atlantoaxial joint dislocation, which was demonstrated by the spiral CT reconstruction clearly but not by the X-ray and CT scan. There were 3 cases of atlantoaxial congenital deformity (1 case of absence of both posterior arch of atlas and odontoid process and 2 cases of maldevelopment of the odontoid process), which were displayed clearly by spiral CT reconstruction, but misdiagnosed as odontoid process fracture and atlantoaxial subluxation by X-ray and CT scan. CONCLUSION: Spiral CT reconstruction can provide the most accurate and integrity imaging information and is very useful in the diagnosis of atlantoaxial injuries and deformity.

[Analysis of implant placement accuracy using freehand in 68 consecutive patients with 97 implants].

PURPOSE: To analyze the accuracy of implant position in simple cases by freehand. METHODS: Ninety-seven implants of 68 patients from 3 surgeons were selected.After operation,the deviations of implant position at shoulder apex and angle were measured using cone-beam CT(CBCT).The mean of three parameters were calculated with SPSS 22.0 software package, and the differences were analyzed between three surgeons,three operation areas,free-end missing and non free-end missing. RESULTS: The deviations of 97 implants were (0.76±0.57)mm，(1.41±0.90)mm，(4.76±3.68)° at shoulder, apex and angle.The deviation of shoulder apex and angle between three surgeons was significantly different(P<0.05). The deviations between left and right group were not significantly different (P>0.05); the deviations between anterior group and left group were significantly different(P<0.05); the deviations between anterior group and right group were not significantly different(P>0.05). The deviation of shoulder between free-end missing area and non free-end missing area was significantly different(P<0.05),other parameters between the two groups were not significantly different(P>0.05). CONCLUSIONS: The deviation of implant placement between surgical guide and mental guide were similar in simple cases. The experience of surgeon was important during freehand implant placement. The deviations were lower when missing tooth is in anterior area than in posterior area, whereas the same at shoulder in non free-end missing area than in free-end missing area.

[Evaluation of the effect of quality control circle activities on improving the nursing quality of patients with periodontitis].

PURPOSE: To study the effect of quality control circle activity on improving nursing quality of patients with periodontitis. METHODS: One hundred and twenty patients with periodontitis admitted to our hospital from January 2016 to December 2017 were selected and divided into experimental group and control group according to the principle of random control, with 60 patients in each group. Patients in both groups received supragingival scaling, subgingival scaling and related symptomatic treatment, patients in the experimental group conducted nursing under the guidance of quality control circle, while patients in the control group received routine nursing. Satisfaction degree, therapeutic effect and gingival index, probe depth, gingival sulcus bleeding index, plaque index and periodontal attachment levels were recorded and compared between the two groups using SPSS 19.0 software package. RESULTS: After quality control circle to guide nursing, the patients' satisfaction (P=0.003) and the total effective rate of treatment was significantly higher than the control group(P=0.002), the incidence of oral health problems in the experimental group was significantly lower than the control group(P=0.037), PD, GI, SBI, PLI and AL levels in the experimental group were significantly lower than the control group(P=0.000). In addition to the tangible achievements，intangible results, such as quality control circles harmonious degree of nursing, sense of responsibility, communication, and problem solving ability, cohesion and quality control methods are improved distinctly in the experimental group. CONCLUSIONS: Quality control circle activity can improve nursing quality of patients with periodontitis.

[The influence of the age of deep caries on eruption of premolars].

PURPOSE: To evaluate the influence of the time of deep caries on eruption of premolars. METHODS: Children in kindergarten in 2010 was selected to check caries of deciduous molars, then baseline data of population and personal oral health records were established. After data collection, from 2010 to 2017, according to the age of deep caries in deciduous molars, they were divided into 4 groups: four-year, five-year, six-year and seven-year. SPSS 20.0 software package was applied to analyze the results. RESULTS: Between 2010 and 2017, 994 children were investigated, including 528 boys and 466 girls. A total of 1220 maxillary first deciduous molars, 1307 maxillary second deciduous molars ,1244 mandibular first deciduous molars and 1253 mandibular second deciduous molars were investigated. At the age of 4 to 7, when the maxillary and mandibular deciduous molars suffered from deep caries, the replacement time of the premolars was earlier than cases with no caries. The difference was statistically significant (P<0.05); When deciduous molar decay occurred in young children, premolars had a tendency to erupt earlier, especially deciduous molars developed deep caries before 5 years, the difference was statistically significant (P<0.05). CONCLUSIONS: Prevention and intervention of dental caries in children is very important. Especially for children under 5 years old, caries in children's molars need early treatment, in order to decrease the impact on normal replacement of permanent teeth.

[Survey on dental caries status of migrant children aged 6-12 years in Minhang district of Shanghai].

PURPOSE: To investigate the prevalence of dental caries among migrant children aged 6-12 years in Minhang district of Shanghai, so as to provide some basic data for children health care. METHODS: Ten thousand and eleven school children in 8 primary schools of Minhang district of Shanghai were investigated by cluster random sampling. Visual examination combined with probe inspection was used to diagnose caries, and then rate of caries and DMFT (decayed，missing and filled teeth) were calculated. SPSS 13.0 software package was used for statistical analysis. RESULTS: The prevalence of caries among children aged 6-12 years was 67.07%, which was significantly higher than that in children from government-owned schools (61.99%)(P<0.01). The prevalence of caries was 75.82% in 6-year-old group and highest compared to other groups. CONCLUSIONS: It can't be optimistic about the caries prevalence among migrant children aged 6-12 years in Minhang district，Shanghai.More attentions should be payed in prevention and early intervention of dental caries for children above 6 years old.

[Is there relationship between pink teeth phenomenon and cause of death?].

OBJECTIVE: To explore the relationship between the pink teeth phenomenon and the cause of death as well as its significance in forensic medicine. METHODS: Inspection method was adopted to observe the pink teeth phenomenon in different causes of death. Ten rats were selected for every experimental groups, which were then divided into two groups: Eight in fresh group with teeth pulled immediately, and two in decayed group with body decayed in water firstly. The teeth pulled from rats were immersed in 75% alcohol and observed at different immersion time. RESULTS: In every fresh groups, pink teeth phenomenon was not observed when they were pulled immediately, whereas it emerged gradually after the teeth immersed in 75% alcohol, and the color showed distinct and constant four hours later. In decayed groups, Pink teeth phenomenon was observed immediately when teeth pulled, it became distinct and constant after one hour's immersion in alcohol. So it was more distinctive in the decayed groups than that in the fresh groups. CONCLUSION: There is no significant connection between the pink teeth phenomenon and the cause of death, thus it may not be subject to forensic identification.

Nanomedicine for treating spinal cord injury.

Spinal cord injury results in significant mortality and morbidity, lifestyle changes, and difficult rehabilitation. Treatment of spinal cord injury is challenging because the spinal cord is both complex to treat acutely and difficult to regenerate. Nanomaterials can be used to provide effective treatments; their unique properties can facilitate drug delivery to the injury site, enact as neuroprotective agents, or provide platforms to stimulate regrowth of damaged tissues. We review recent uses of nanomaterials including nanowires, micelles, nanoparticles, liposomes, and carbon-based nanomaterials for neuroprotection in the acute phase. We also review the design and neural regenerative application of electrospun scaffolds, conduits, and self-assembling peptide scaffolds.

Early profiles of axonal growth and astroglial response after spinal cord hemisection and implantation of Schwann cell-seeded guidance channels in adult rats.

We previously demonstrated that transplantation of Schwann cell-seeded channels promoted the regrowth of injured axons in the adult spinal cord. It is not clear, however, whether injured axons recapitulate the developmental scenarios to accomplish regeneration. In the present study, we investigated the early events associated with axonal regrowth after spinal cord hemisection at the eighth thoracic level and implantation of a Schwann cell-seeded minichannel in adult rats. Animals were sacrificed at postoperative days (PO) 2, 4, 7, and 14. Anterograde tracing with fluoro-ruby showed that regenerating axons grew into the graft prior to PO2 and reached the distal end of the channel at PO7. These axons expressed both embryonic neural cell adhesion molecule (E-NCAM) and growth associated protein-43 (GAP-43). Although the expression of E-NCAM decreased by PO7, that of GAP-43 remained high throughout the first 2 weeks after implantation. A close relation of vimentin-positive astroglia to the growing axons in the host tissue suggested a contact-mediated role of these cells in axon guidance. Aggregation of glial fibrillary acidic protein (GFAP)-positive astrocytes together with the increased expression of chondroitin sulfate proteoglycans (CSPGs) starting at PO7 appeared to inhibit axonal growth at the host-graft interface. Thus, adult regenerating axons and astroglia do express developmentally related molecules that may facilitate axonal growth into a permissive graft at the early phase of injury and regeneration. These results suggest that molecules and astroglia essential to development are both important in influencing axonal regrowth in the adult spinal cord.