SEM studies on vessels in ferns. 2. Pteridium

Xylem from roots and rhizomes of two infraspecific taxa of Pteridium aquilinum was studied by means of scanning electron microscopy (SEM). All tracheary elements proved to be vessels. End wall perforation plates were all scalariform, lacked pit membrane remnants in at least the central part of the perforation plate, and varied with respect to width of bars, from wide to tenuous, and with respect to presence of pit membrane remnants. In addition, porose pit membranes on walls that are likely all lateral vessel-to-vessel walls must be considered to be perforations also, although different from those on end walls. Lateral wall perforation plates, hypothesized by one worker on the basis of tylosis presence but denied by another on the basis of light microscopy, were confirmed by demonstration of pores with SEM. In addition, lateral walls of Pteridium vessels bear some grooves interconnecting pit apertures; this feature is newly figured by SEM for ferns. Lateral wall pitting that is not porose may either have striate thickenings of the primary wall or be smooth. Vessel presence and degree of specialization in Pteridium vessels may bear a relationship to the wide ecological tolerances of the genus.     

皱纹盘鲍稚鲍剥离后大量死亡的原因和防治方法初探

本文报告了对大连地区皱纹盘鲍（Ｈ．ｄｉｓｃｕｓ）人工育苗过程中,稚鲍剥离后大量死亡现象的初步研究工作。实验表明,稚鲍赖以生存的波纹板上饵料残渣的积累和腐败,微生物的大量繁殖,粘液状物质的形成与稚鲍的死亡密切相关。实验中从病鲍个体及粘液状中分离出了十株优势菌,筛选出了四种有效的杀菌药物,并测出了每种药物的ＭＩＣ值,实验结果在生产实际中应用取得了良好的效果。     

A freeze-etch study of angular marginal-plate-containing peroxisomes in the proximal tubules of bovine kidney

Summary The ultrastructure of peroxisomes in the proximal nephron tubules of bovine kidney cortex was studied using ultrathin-sectioning, diaminobenzidine cytochemistry for the visualization of catalase, and by freeze-fracture. Peroxisomes in this nephron segment are up to 1.5 m in diameter and exhibit a peculiar angular shape, which is probably related to the occurrence of multiple straight plate-like inclusions (marginal plates) in the matrix of peroxisomes; they lie directly underneath the peroxisomal membranes. The peroxisomal membrane in such regions follows the outline of the marginal plate. The peculiar shape of peroxisomes allows their unequivocal identification in freeze-fracture preparations. Peroxisomal membranes are recognized by their flat, often rectangular appearance. Intramembrane particles are much more numerous on P-fracture faces than on E-fracture faces. A crystalline lattice-structure with a periodicity of approximately 10 nm can be observed on the flat rectangular areas of E-fracture faces. This lattice structure is intensified after prolonged freeze-etching. Intramembranous particles seem to be superimposed over this pattern. The crystalline pattern on the E-fracture faces of peroxisomal membranes is probably not a membrane structure but it reveals the structure of the membrane-associated marginal plates. A cast of the marginal-plate surface may be generated by a collapse of the peroxisomal membrane half onto the immediately underlying matrix inclusion.     

肱骨近端加压锁定钢板与传统钢板治疗肱骨近端骨折的临床疗效比较

目的比较肱骨近端加压锁定钢板与传统钢板治疗肱骨近端骨折的临床治疗效果。方法选取我院2014年1月~2015年1月骨外科门诊收治的肱骨近端骨折患者60例,随机分为治疗组和对照组各30例。治疗组采用肱骨近端加压锁定钢板治疗,对照组采用传统钢板治疗,比较两组的Neer功能评分、骨折愈合时间、并发症发生情况。结果两组患者Neer功能评分与治疗前比较均有明显提高,治疗组提高水平明显优于对照组;而且治疗组骨折愈合时间、并发症发生情况均低于对照组,两组比较差异具有统计学意义(P0.05)。结论肱骨近端加压锁定钢板相比传统钢板治疗肱骨近端骨折的临床疗效更优,促进了患者的骨折愈合速度,降低了并发症发生率,具有临床推广和应用价值。     

Inference about the Number of Resident Bacterial Strains when Sampling from Plate Colonies

This paper deals with making inferences about the number of resident bacterial strains in mice gut based on the number of strains of bacteria found in a random sample of colonies derived from plated faecal material. It is shown that for what seems to be a natural way to test the hypothesis that there is only one resident bacterial strain against the alternative that there is more than one resident strain the probability of a Type II error may be unacceptably large. It is also shown that given the sample contains only one bacterial strain the probability that the animal has only one resident strain converges to unity at a geometric rate as the sample size increases.     

Specificity and development of innervation pattern of Xenopus pectoralis muscle

Multielectrode recordings were used to identify and measure the axonal inputs to each end plate on contiguous surface fibers covering about 25% of the Xenopus pectoralis muscle in mature and developing animals. The mature innervation pattern was remarkably precise. Individual axons tended to innervate fibers of similar input resistance (R_in) in compact motor units restricted to only a portion of the region studied. Motor units comprising fibers of similar R_in overlapped mainly near their borders. Most fibers had two end plates. In more than 80% of these fibers, both end plates received input from the same axon. In 57%, this was the only input to both end plates. This implies a powerful mechanism for excluding or eliminating inputs from other axons. About 16% of the mature junctions showed focal polyneuronal innervation, with the weaker end plate potential component often less than 1 mV in noncurarized preparations. However, we have no evidence that the weaker inputs were being eliminated. During development, motor units became more compact, which was associated with synapse elimination; but from the earliest times studied, soon after metamorphosis when many fibers were adding second end plates, a majority of those that had two end plates were innervated at both sites by the same axon. © 1996 John Wiley & Sons, Inc.     

MIPO技术结合锁定加压钢板、顺行交锁髓内钉及锁定加压钢板治疗肱骨干中段骨折疗效的对比研究

摘要 目的：探讨微创经皮钢板内固定（MIPO）技术结合锁定加压钢板、顺行交锁髓内钉、锁定加压钢板治疗肱骨干中段骨折的疗效。方法：选择2016年2月至2019年2月我院收治的126例肱骨干中段骨折患者，采用随机数字表法将其分为三组，MIPO组（42例）采用MIPO技术结合锁定加压钢板固定治疗，髓内钉组（42例）采用顺行交锁髓内钉固定治疗，钢板组（42例）采用锁定加压钢板固定治疗。所有患者术后随访12个月，比较三组手术时间、术中出血量、术后住院时间、骨折愈合时间、术前和术后第12个月美国加州大学肩关节评分系统（UCLA）评分、Mayo肘关节功能评分（MEPS）、欧洲五维健康量表(EQ-5D)评分以及并发症发生率。结果：MIPO组和髓内钉组的术中出血量与术后住院时间均少于钢板组（P＜0.05），MIPO组和髓内钉组之间无统计学差异（P＞0.05）。MIPO组、钢板组骨折愈合时间短于髓内钉组（P＜0.05），MIPO组、钢板组之间无统计学差异（P＞0.05）。MIPO组、钢板组术后第12个月UCLA评分均高于髓内钉组（P＜0.05），MIPO组、钢板组之间无统计学差异，第12个月MEPS无差异（P＞0.05）。术后第12个月MIPO组、钢板组EQ-5D评分高于髓内钉组（P＜0.05），MIPO组、钢板组之间无统计学差异（P＞0.05）。三组桡神经损伤、肩峰损伤发生率相比较，差异有统计学意义（P＜0.05），桡神经损伤以钢板组发生率最高，肩峰损伤以髓内钉组发生率最高。结论：MIPO技术结合锁定加压钢板具有微创、术后恢复快、对肩关节功能及生活质量的影响较小、术后并发症较少的优势，是肱骨干中段骨折较为理想的治疗方式。     

Erythromelalgia Mutation Q875E Stabilizes the Activated State of Sodium Channel Nav1.7

The human voltage-gated sodium channel Nav1.7 plays a crucial role in transmission of noxious stimuli. The inherited pain disorder erythromelalgia (IEM) has been linked to Nav1.7 gain-of-function mutations. Here we show that the IEM-associated Q875E mutation located on the pore module of Nav1.7 produces a large hyperpolarizing shift (−18 mV) in the voltage dependence of activation. Three-dimensional homology modeling indicates that the side chains of Gln-875 and the gating charge Arg-214 of the domain I voltage sensor are spatially close in the activated conformation of the channel. We verified this proximity by using an engineered disulfide bridge approach. The Q875E mutation introduces a negative charge that may modify the local electrical field experienced by the voltage sensor and, upon activation, interact directly via a salt bridge with the Arg-214 gating charge residue. Together these processes could promote transition to, and stabilization of, the domain I voltage sensor in the activated conformation and thus produce the observed gain of function. In support of this hypothesis, an increase in the extracellular concentration of Ca²⁺ or Mg²⁺ reverted the voltage dependence of activation of the IEM mutant to near WT values, suggesting a cation-mediated electrostatic screening of the proposed interaction between Q875E and Arg-214.     

Skeletal kinematics of the midtarsal joint during walking: Midtarsal joint locking revisited

The kinematics of the human foot complex have been investigated to understand the weight bearing mechanism of the foot. This study aims to investigate midtarsal joint locking during walking by noninvasively measuring the movements of foot bones using a high-speed bi-planar fluoroscopic system. Eighteen healthy subjects volunteered for the study; the subjects underwent computed tomography imaging and bi-planar radiographs of the foot in order to measure the three-dimensional (3D) midtarsal joint kinematics using a 2D-to-3D registration method and anatomical coordinate system in each bone. The relative movements on bone surfaces were also calculated in the talonavicular and calcaneocuboid joints and quantified as surface relative velocity vectors on articular surfaces to understand the kinematic interactions in the midtarsal joint. The midtarsal joint performed a coupled motion in the early stance to pronate the foot to extreme pose in the range of motion during walking and maintained this pose during the mid-stance. In the terminal stance, the talonavicular joint performed plantar-flexion, inversion, and internal rotation while the calcaneocuboid joint performed mainly inversion. The midtarsal joint moved towards an extreme supinated pose, rather than a minimum motion in the terminal stance. The study provides a new perspective to understand the kinematics and kinetics of the movement of foot bones and so-called midtarsal joint locking, during walking. The midtarsal joint continuously moved towards extreme poses together with the activation of muscle forces, which would support the foot for more effective force transfer during push-off in the terminal stance.