Age,growth and reproductive biology of the silky shark,Carcharhinus falciformis,and the scalloped hammerhead,Sphyrna lewini,from the northwestern Gulf of Mexico

Synopsis The silky shark, Carcharhinus falciformis, and scalloped hammerhead, Sphyrna lewini, represent >80% of the shark by-catch of the winter swordfish/tuna longline fishery of the northwestern Gulf of Mexico. This catch represents a potential supplemental fishery, yet little is known of the life histories of the two species. This report relates reproductive biology data to age and growth estimates for 135 C. falciformis and 78 S. lewini. Unlike other regional populations, C. falciformis in the Gulf of Mexico may have a seasonal 12 month gestation period. Males mature at 210–220 cm TL (6–7 yr); females at >225 cm TL (7–9 yr). Application of age at length data for combined sexes produced von Bertalanffy growth model parameter estimates of L_∞ = 291 cm TL, K = 0.153, t₀ = −2.2 yr. Adult male S. lewini outnumbered adult females in catches because of differences in the distributions of the sexually segregated population. Males mature at 180 cm TL (10 yr); females at 250 cm TL (15 yr). von Bertalanffy parameter estimates for combined sexes of this species were L_∞ = 329 cm TL, K = 0.073, t_o = −2.2 yr.     

Age and growth of the Australian sharpnose shark,Rhizoprionodon taylori,from north Queensland,Australia

Synopsis Age and growth were studied inRhizoprionodon taylori using specimens caught in Cleveland Bay, North Queensland, Australia. Von Bertalanffy growth parameters were estimated using three different techniques: vertebral ageing, back calculation and length frequency. Vertebrae from 138 specimens were sectioned and narrow circuli counted to estimate age. Marginal increment analysis verified that circuli were produced annually in late summer, probably as a result of stress during the mating season. The oldest female was 7 and male 6 years old. Von Bertalanffy growth parameters estimated from vertebral ageing data for males were t_O = 0.410 yr, K = 1.337, L = 652.2 mm, and for females t_O = 0.455 yr, K = 1.013 and L = 732.5 mm. Growth parameters determined by length frequency and back calculation techniques concurred with those from vertebral ageing. Growth of the 0+ age class was very rapid, averaging 140% of the size at birth in the first year. Males and females matured after only one year, the lowest age at maturity reported in the family Carcharhinidae. Annual growth increments decreased rapidly after maturity, and little growth occurred after three years.     

“Naked” spinal cord on a non-segmented baton-like bony structure in the tail of the electric fish Eigenmannia virescens (Gymnotoidei)

Summary The caudal spinal cord of Eigenmannia virescens is not enclosed in a neural canal of the vertebral column. In fact, a segmented vertebral column with neural and ventral arches is lacking and replaced by a non-segmented baton-like bony structure on which the free spinal cord is located. The baton consists of calcified bone tissue with bone cells. Individual differences exist as far as the length of the rod is concerned. The electromotor neurons of this caudal part of the spinal cord are histochemically acetylcholinesterase-positive. The electrocytes which surround this part of the spinal cord show strong enzymatic actitivity on the posterior innervated face. However, there is also activity on the non-innervated lateral and anterior faces.     

网袋强化椎体成形术在骨质疏松椎体骨折治疗中的经验教训

摘要 目的：探讨和总结使用网袋强化椎体成形术在骨质疏松椎体骨折围手术期的注意事项及相关对策。方法：回顾性分析2017年6月到2020年6月3年时间内,使用网袋强化椎体成形术治疗骨质疏松性椎体骨折患者共计112例。统计和比较患者在围手术期的各项指标,分析穿刺失败的原因及相关危险因素。结果：112例患者共涉及138个椎体。其中一期穿刺失败率（骨水泥分布不佳）为47个,占34.0%。骨水泥注入3 mL以下者为19个,占13.8%。骨水泥渗漏为36个,占26.1%。所有患者在术后3天及3月复查, VAS评分和ODI评分较前均有显著改善(P<0.05)。所有患者均未出现严重并发症(P>0.05)。结论：网袋强化椎体成形术在骨质疏松性椎体骨折的治疗中是一种理想的治疗方式,但在具体过程中仍有相关的经验和教训需要整理和总结。     

彩色多普勒超声测量椎动脉血流量对后循环缺血的诊断价值

目的：探讨彩色多普勒超声技术测量椎动脉血流量对后循环缺血（PCI）的诊断价值。方法：选取2012年1月至2013年1月在本院神经内科住院并接受治疗的PCI患者58例作为观察组,另选取同期住院并确诊为非后循环缺血症的患者50例作为对照组。所有患者均接受颈部血管超声检查,测量椎动脉内径及血流量,观察组患者需行头颅CTA检查,比较两组患者的椎动脉内径、血流量及颈动脉硬化斑块发生率等。结果：观察组患者的椎动脉内径及血流量明显低于对照组,两组比较差异有统计学意义（P〈0．01）;观察组颈动脉硬化斑块的发生率为77．5％（44例）,对照组颈动脉硬化斑块的发生率为42％（21例）,两组比较差异有统计学意义（P〈0．05）。无狭窄、轻度狭窄、重度狭窄及闭塞的椎动脉血流量的变化（此处所指的血流量是指小于200mL/min那部分患者）有明显差异（P〈0．05）。结论：与头颅CTA对比检查,彩色多普勒具有直接、准确、方便及可重复性等优点,可有效的诊断后循环缺血症状。     

椎体后凸成形术治疗骨质疏松性椎体压缩骨折的临床研究

摘要目的：随着老龄人口的增多,老年骨质疏松性椎体压缩性骨折（Osteoporotic Vertebral Compression Fracture,ovcr）的发病率也逐年增高。本文探讨椎体后凸成形术（PercutaneousKyphoplasty,PKP）对0VCF的疼痛缓解及功能改善等方面的临床疗效,并探讨其发展过程、作用机理及并发症的防治。方法：回顾性分析2007年1月至2011年12月应用PKP治疗的OVCF158例患者,其中男55例,女103例;患者年龄52--87岁,平均68．7岁。对患者术前、术后1日、术后3个月随访时的疼痛（VAs）及功能情况（ODD进行评价,并对以上数据进行配对t检验。结果：全部病例均顺利完成手术,3例出现椎体间隙渗漏,5例渗漏至椎体周缘,2例骨水泥渗漏至椎管内,无神经根和脊髓受压症状。VAS评分评价,术前（7．60±0．95）分,术后1日（1．00±0．74）分,术后三个月（0．20±0．48）分,术后疼痛缓解有统计学意义（P〈0．01）;ODI,术前（84．94±4-36）％,术后1日（20．47±3．61）％,术后三个月（9．85±3．43m,术后功能恢复有统计学意义（P〈0．01）。结论：PKP术后1日患者疼痛及功能较术前均有明显改善,术后3个月较术后1日亦有进一步的改观。术后后续应用治疗骨质疏松药物及康复治疗可改善患者骨质,预防相邻椎体及其他部位骨质骨折,使疗效更加满意。PKP为治疗OVCF提供了一种安全、有效的方法,可以迅速缓解疼痛,改善功能,具有广阔的应用前景。     

椎体静脉稀疏区注入骨水泥对PVP术中骨水泥渗漏的影响

目的:探讨椎体静脉稀疏区注入骨水泥对骨质疏松椎体压缩性骨折患者行经皮穿刺椎体成形术(percutaneous vertebroplasty,PVP)术中骨水泥渗漏的影响。方法:选择西安交通大学第二附属医院2014年1月至2018年6月收治的61例骨质疏松椎体压缩性骨折患者,根据骨水泥注入区域的不同,将所有患者分为A组(30例)及B组(31例),A组骨水泥注入区域为椎体静脉密集区(椎体中1/3平面处),B组骨水泥注入区域为椎体静脉稀疏区(椎体上1/3及下1/3平面处),对比两组的骨水泥渗漏率,术前、术后6个月时的视觉模拟评分(Visual analogue scale,VAS),治疗中的骨水泥用量、椎体高度恢复率及cobb角恢复度数。结果:B组的骨水泥渗漏率及骨水泥用量均明显低于A组(P0.05)。两组的VAS评分、椎体高度恢复率、cobb角恢复情况对比差异无统计学意义(P0.05)。结论:与椎体静脉密集区相比,在椎体静脉稀疏区注入骨水泥可显著降低骨质疏松椎体压缩性骨折患者PVP术中骨水泥渗漏率,椎体静脉稀疏区可作为PVP术中骨水泥注射的一个相对安全区域。     

一个基于能量的突触可塑性模型

研究表明能量可能是支配神经元活动的统一原则,编码能力与能量成本的比率最大化被认为是突触连接在选择性压力下改变的关键原则之一,这意味着突触范围内能量的变化与突触可塑性有关。为此,建立一个基于能量的突触可塑性模型。当突触后膜瞬时功率高于功率阈值时突触权重增加,反之突触权重下降。该模型可再现脉冲频率依赖可塑性以及脉冲时间依赖可塑性这两种主要的突触可塑性实验结果,并且和其他公认的突触可塑性模型相比具有优越性。结果表明,能量是影响突触可塑性的关键因素,对进一步理解突触连接的选择性和神经网络动力学特征提供了一个新思路。