Comparative neuroanatomy of ctenophores: Neural and muscular systems in Euplokamis dunlapae and related species

Ctenophora is an early-branching basal metazoan lineage, which may have evolved neurons and muscles independently from other animals. However, despite the profound diversity among ctenophores, basal neuroanatomical data are limited to representatives of two genera. Here, we describe the organization of neuromuscular systems in eight ctenophore species focusing on Euplokamis dunlapae—the representative of the lineage sister to all other ctenophores. Cydippids (Hormiphora hormiphora and Dryodora glandiformis) and lobates (Bolinopsis infundibulum and Mnemiopsis leidyi) were used as reference platforms to cover both morphological and ecological diversity within the phylum. We show that even with substantial environmental differences, the basal organization of neural systems is conserved among ctenophores. In all species, we detected two distributed neuronal subsystems: the subepithelial polygonal network and the mesogleal elements. Nevertheless, each species developed specific innovations in neural, muscular, and receptor systems. Most notable Euplokamis-specific features are the following: (a) Comb nerves with giant axons. These nerves directly coordinate the rapid escape response bypassing the central integrative structure known as the aboral sensory organ. (b) Neural processes in tentacles along the rows of “boxes” providing structural support and located under striated muscles. (c) Radial muscles that cross the mesoglea and connect the outer wall to the aboral canal. (d) Flat muscles, encircling each meridional canal. Also, we detected a structurally different rectangular neural network in the feeding lobes of Lobata (Mnemiopsis/Bolinopsis) but not in other species. The described lineage-specific innovations can be used for future single-cell atlases of ctenophores and analyses of neuronal evolution in basal metazoans.     

运动学对线应用于全膝关节置换术的研究进展

全膝关节置换术是目前治疗终末期膝关节骨性关节炎最有效的方法之一，全膝关节置换术后膝关节功能、术后膝关节疼痛与术后下肢力线有着密切的关系。目前膝关节置换术下肢对线方式主要采用机械力学对线方法，该方法可以改善膝关节功能，但是有部分患者也会产生术后膝关节的疼痛、活动受限等并发症，导致术后患者满意度较差。近些年越来越多的研究开始关注运动力学对线技术并应用于临床。运动学对线技术旨在重建患者的解剖结构，将膝关节假体运动轴与膝关节生理性运动轴保持一致，减少膝关节周围软组织和韧带的松解，实现膝关节生理性运动。该文就运动力学对线方法在全膝关节置换术中的应用进展作一综述。     

Larger muscle mass of the upper limb correlates with lower amplitudes of deltoid MEPs following transcranial stimulation

To perform spinal surgery safely, it is important to understand the risk factors, including factors that negatively influence intraoperative neuromonitoring (IONM). Transcranial motor evoked potentials (TcMEPs) are important in IONM. Therefore, we aimed to investigate whether muscle mass affects the waveforms of TcMEPs to understand the risk factors influencing TcMEPs. We enrolled 48 patients with thoracolumbar spinal diseases who underwent surgery at our facility between April 2015 and March 2018. Before surgery, the body composition, including muscle mass and fat mass, of all patients was measured using bioelectrical impedance analysis (BIA). During surgery, cranial stimulation under general anesthesia was used to derive TcMEPs, enabling us to measure the amplitude, using the control wave of the TcMEPs of the deltoid muscles and the abductor digiti minimi (ADM) muscles. We found a negative correlation between the amplitude of deltoid-muscle TcMEPs and muscle mass of the upper limb. The amplitude of deltoid-muscle TcMEPs did not correlate with the skeletal muscle index (SMI), muscle mass of the lower limb, or body fat mass. The amplitude of ADM-muscle TcMEPs did not correlate with SMI, muscle mass of any limb, or body fat mass. In conclusion, a larger muscle mass of the upper limb correlated with a lower amplitude of deltoid-muscle TcMEPs. By contrast, there was no correlation between the muscle mass of the upper limb and the amplitude of ADM-muscle TcMEPs. These findings suggest that TcMEPs of the ADM are less influenced by muscle mass and are more stable than those of the deltoid.     

Humerus osteology,myology, and finite element structure analysis of Cheloniidae

Adaptation of osteology and myology lead to the formation of hydrofoil foreflippers in Cheloniidae (all recent sea turtles except Dermochelys coriacea) which are used mainly for underwater flight. Recent research shows the biomechanical advantages of a complex system of agonistic and antagonistic tension chords that reduce bending stress in bones. Finite element structure analysis (FESA) of a cheloniid humerus is used to provide a better understanding of morphology and microanatomy and to link these with the main flipper function, underwater flight. Dissection of a Caretta caretta gave insights into lines of action, that is, the course that a muscle takes between its origin and insertion, of foreflipper musculature. Lines of action were determined by spanning physical threads on a skeleton of Chelonia mydas. The right humerus of this skeleton was micro-CT scanned. Based on the scans, a finite element (FE) model was built and muscle force vectors were entered. Muscle forces were iteratively approximated until a uniform compressive stress distribution was attained. Two load cases, downstroke and upstroke, were computed. We found that muscle wrappings (m. coracobrachialis magnus and brevis, several extensors, humeral head of m. triceps) are crucial in addition to axial loading to obtain homogenous compressive loading in all bone cross-sections. Detailed knowledge on muscle disposition leads to compressive stress distribution in the FE model which corresponds with the bone microstructure. The FE analysis of the cheloniid humerus shows that bone may be loaded mainly by compression if the bending moments are minimized.     

Nipple leiomyoma: A rare neoplasm with a broad spectrum of histologic appearances

Cutaneous leiomyomas are rare benign smooth‐muscle tumors. These lesions are distinguished based on their cell of origin and are subclassified as pilar leiomyoma, angioleiomyoma, and genital‐type leiomyoma. Nipple leiomyoma is the least common genital‐type leiomyoma, arising from the dartoic muscle cell of the nipple. Histologic examination of the lesion is necessary for definitive diagnosis, and these uncommon tumors can pose a diagnostic challenge. We describe herein a series of six nipple leiomyomas with a spectrum of histologic appearances.     

The influence of tongue strength on children's performance in computer games reliant on lingual force generation

Oral motor exercises, for recovering tongue strength, can be integrated with computer games to increase motivation, especially for treatments in children. The aim of this study was to investigate the influence of tongue strength on motor performance in computer games reliant on lingual force generation. An observational study was carried out at a speech-language pathology outpatient university clinic. Twenty participants (10 with normal tongue strength and 10 with reduced tongue strength) aged 8-13 years used an intra-oral joystick controlled by the tongue to play six computer games during which they had to reach targets that appeared on the screen. Motor performance was measured by the number of attempts to score and the time during which the target force was maintained. Tongue motor performance was compared between groups and across directions of tongue movement, resistance force levels, order of target appearance, continuous force application time on the target, age and sex. Children with normal tongue strength had a lower number of attempts to score (P = .014) and maintained the target force for longer periods (P = .002) than those with reduced tongue strength. The performance was better for both groups (a) in the downward direction compared with the performance in other directions, (b) in games with the lowest resistive force level (0.5 N) compared to those with other levels of resistive force and (c) in the second and third rounds compared with the first round. There were no gender-related differences in performance. Older participants performed better than younger participants. Tongue strength, direction of movement, force to reach the target, time of continuous force application, order of target appearance and age influenced tongue motor performance.     

微创全髋关节置换后的影像学评估

背景:微创全髋关节置换后难免发生并发症,目前临床常用术后评估的影像学手段多种多样,各有利弊。目的:介绍X射线片、CT、MRI等影像学检查在微创全髋关节置换后疗效评估方面的应用价值及研究进展。方法:由第一作者检索PubMed数据库、中国知网、万方数据库中2000至2020年出版的文献,英文检索词为"surgical injury,MRI,minimally invasive,muscle trauma";中文检索词为"微创全髋关节置换术,影像,评估,肌肉损伤",对微创全髋关节置换过程中不同入路的特点及其对髋周肌群影响的影像检查结果进行总结分析。结果与结论:①X射线片是全髋关节置换后患者复查的首选检查;②骨单光子发射CT不易受到金属伪影的影响,在关节置换患者中显示出更高的敏感性和特异性;③MRI成为评估髋周肌群,特别是肌肉形态学改变的金标准;④血清炎性细胞因子水平作为肌肉损伤的标志物,是评估微创全髋关节置换的一种特异而客观的方法;⑤提示微创全髋关节置换极大地避免了肌肉和肌腱的切开或剥离,减少了术后髋关节脱位及脂肪液化坏死等风险;老年患者因其肌肉修复再生能力减弱,在进行全髋关节置换过程中使用微创术式有着独特的临床价值;影像学检查能够客观准确地评估微创手术的患者获益。