Cone synapses in mammalian retinal rod bipolar cells

Some mammalian rod bipolar cells (RBCs) can receive excitatory chemical synaptic inputs from both rods and cones (DBC_R2), but anatomical evidence for mammalian cone‐RBC contacts has been sparse. We examined anatomical cone‐RBC contacts using neurobiotin (NB) to visualize individual mouse cones and standard immuno‐markers to identify RBCs, cone pedicles and synapses in mouse and baboon retinas. Peanut agglutinin (PNA) stained the basal membrane of all cone pedicles, and mouse cones were positive for red/green (R/G)‐opsin, whereas baboon cones were positive for calbindin D‐28k. All synapses in the outer plexiform layer were labeled for synaptic vesicle protein 2 (SV2) and PSD (postsynaptic density)‐95, and those that coincided with PNA resided closest to bipolar cell somas. Cone‐RBC synaptic contacts were identified by: (a) RBC dendrites deeply invaginating into the center of cone pedicles (invaginating synapses), (b) RBC dendritic spines intruding into the surface of cone pedicles (superficial synapses), and (c) PKCα immunoreactivity coinciding with synaptic marker SV2, PSD‐95, mGluR6, G protein beta 5 or PNA at cone pedicles. One RBC could form 0‐1 invaginating and 1‐3 superficial contacts with cones. 20.7% and 38.9% of mouse RBCs contacted cones in the peripheral and central retina (p < .05, n = 14 samples), respectively, while 34.4% (peripheral) and 48.5% (central) of cones contacted RBCs (p > .05). In baboon retinas (n = 4 samples), cone‐RBC contacts involved 12.2% of RBCs (n = 416 cells) and 22.5% of cones (n = 225 cells). This suggests that rod and cone signals in the ON pathway are integrated in some RBCs before reaching AII amacrine cells.     

Factors associated with visual acuity in patients with cystoid macular oedema and Retinitis Pigmentosa

Purpose: Retinitis pigmentosa is the most common inherited retinal dystrophy. The factors associated with visual acuity in patients with other retinal diseases are well known, but are poorly understood in patients with retinitis pigmentosa. This knowledge is useful for prognosis and to support secondary endpoints in clinical trials.

Methods: We conducted a cross-sectional study of consecutive patients recruited from the inherited retinal disease service from January 2012 to December 2012. Central macular thickness (CMT) was measured using spectral domain optical coherence tomography.

Results: Data were available for 81 patients and 162 eyes. After multivariable analyses, older age, earlier age of onset of symptoms, and thicker CMT were associated with lower visual acuity. Gender and inheritance pattern were not associated with visual acuity. Each decade older age, younger age of onset, and thicker CMT was associated with 0.12, 0.10, and 0.11 worse logarithm of the minimal angle of resolution units of visual acuity, respectively (p < 0.05 for all).

Conclusions: Age, age of onset, and CMT are associated with visual acuity and important factors to measure in studies of retinitis pigmentosa.     

西安地区成人改良Jackson骶骨棒棒道影像学测量

目的 通过收集西安地区成人的影像学资料,为改良Jackson骶骨棒的操作提供解剖学数据参考。方法 将100例健康成年人作为研究对象,对其进行三维CT扫描,获得所需数据,将数据录入Mimics软件中处理,利用软件确定棒道入口,测量棒道长度,对不同性别间进行统计学分析。结果 男性测得棒道长度为（35.05±6.19） mm,最大值为52 mm;女性为（34.19±5.84） mm,最大值为46 mm。男性骶骨棒棒道长度略大于女性,但差异无统计学意义（P＞0.05）。结论 经测量100例西安地区健康成人改良Jackson骶骨棒棒道长度得知,术中男性骶骨棒棒道深度应控制在52 mm以内,女性控制在46 mm以内,但个体差异较大,术前进行测量可指导手术医师制定手术方案,提高手术安全性。     

A Simple Route to Rod‐Coil Block Copolymers of Oligo‐ and Polythiophenes with PMMA and Polystyrene

A simple and efficient approach for the preparation of rod‐coil block copolymers comprising oligo‐ and polythiophenes blocks together with PMMA or PS blocks is described. The block copolymers were prepared using a two‐step procedure. α,ω‐dicarboxy‐terminated oligothiophenes and carboxy terminated poly(3‐hexylthiophene) were first prepared. These were then reacted with P₄S₁₀ in a second step to generate the α,ω‐thioester terminated oligothiophenes and poly(3‐hexylthiophene)s which were subsequently used in a one‐pot reaction as RAFT polymerization agents with methylmethacrylate and styrene. The di‐ and tri‐block copolymers hence obtained were fully characterized, both in solution and as thin films.

     

Genesis of rods in the zebrafish retina occurs in a microenvironment provided by polysialic acid‐expressing Müller glia

Polysialic acid (polySia) is a posttranslational modification of the neural cell adhesion molecule NCAM, which in the vertebrate brain is dynamically regulated during development and crucially involved in developmental and adult neurogenesis. In the fish retina, new neurons are persistently generated, but the possible contribution of polySia has not yet been addressed. Here we used immunohistochemistry with NCAM‐ and polySia‐specific antibodies to study spatiotemporal expression patterns of NCAM and polySia in the developing and mature zebrafish retina. As early as 2.3 days postfertilization (dpf), NCAM but not polySia was detected on cell somata and fibers of the developing retina. At 4.3 dpf polySia immunoreactivity first appeared in the ventral retina and was localized to the nascent outer nuclear layer (ONL). In mature zebrafish, polySia immunoreactivity in the ONL extended to the entire retina. Colocalization with rhodopsin‐EGFP in transgenic zebrafish or the Müller glia‐specific protein cellular retinaldehyde‐binding protein (CRALBP) revealed that polySia immunoreactivity was confined to the compartment of radial Müller glia processes crossing the ONL and to a small band of processes positioned proximal to the horizontal cell layer of the mature retina. As shown by 5‐bromo‐2‐deoxyuridine (BrdU) labeling, both newly generated rod precursors within the mature ONL and precursors of the marginal zone were polySia‐negative. Thus, polySia‐negative rod precursors of the mature zebrafish retina face a polySia‐NCAM‐positive microenvironment presented by radial Müller glia. In view of the prominent role of polySia in other neurogenic systems, this pattern indicates that polySia provides environmental cues that are relevant for the generation of new rods. J. Comp. Neurol. 518:636–646, 2010. © 2009 Wiley‐Liss, Inc.     

Labor analgesia for the parturient with prior spinal surgery: what does an obstetrician need to know?

Administration of lumbar epidural analgesia in a parturient with previous spinal surgery presents a unique challenge to the anesthesiologist. These challenges (difficulties) range from inability to identify the epidural space, multiple attempts before catheter insertion, vascular trauma, and/or subdural local anesthetic injection to accidental dural puncture. The literature documenting management of labor analgesia in pregnant women with prior spinal surgery is limited to a handful of case reports. This author is not aware of any other review articles in English literature discussing special considerations for labor analgesia in parturients presenting with history of prior spinal instrumentation.     

药棒循经推按法治疗脑卒中偏瘫42例观察

目的:观察药棒循经推按法对治疗脑卒中偏瘫的效果。方法:84例随机分为观察组和对照组各42例,两组均用西药常规治疗及康复训练,观察组加用药棒循经推按法治疗。结果:与治疗前比较治疗4周后两组FMA积分改善率无显著性差异(P0.05),治疗8周后有显著性差异(P0.05);两组间比较,治疗4周后FMA积分及MBI指数无显著性差异(P0.05),治疗8周后观察组优于对照组(P0.05)。结论:西药常规治疗及康复训练配合药棒循经推按法治疗脑卒中偏瘫有较好效果。     

Enamel: From brittle to ductile like tribological response

OBJECTIVES: To identify the intrinsic nano-scale wear mechanisms of enamel by comparing it with that of highly brittle glass, and highly ductile copper and silver monocrystals. METHODS: A sharp cube corner indenter tip (20-50nm radius) was used to abrade glass, enamel as well as copper and silver monocrystals. Square abraded areas (5mumx5mum, 10mumx10mum) were generated with loads of 50muN for enamel and 100muN for the remaining materials (2D abrasion). The normal load and displacement data were utilized in a complementary manner to support the comparison. In addition normal and lateral forces were simultaneously measured along 10mum single scratched lines (1D abrasion). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were also used to characterise the worn areas and debris. RESULTS: The sharp tip cuts into and ploughs the specimens creating a wedge or ridge of material ahead of itself which eventually detaches, for the ductile materials and at high loads in enamel. For glass and enamel at low loads, the indenter tip ploughs into the material and the removed material is redistributed and pressed back into the abraded area. CONCLUSIONS: The wear behaviour of enamel at the nano-level resembles that obtained with glass at low loads (50muN) and that obtained with metal mono-crystals at high load (100muN). The role of the microstructural heterogeneity in the wear behaviour of enamel is considered in the discussion. The relevance to clinical wear of enamel is also considered.     

锁孔和锁钉杆过渡配合交锁髓内钉内固定骨折断端的生物稳定性

背景：随着交锁髓内钉的广泛使用,使骨折延迟愈合、交锁钉断裂等问题逐渐显露出来,在此情况下,一种锁孔和锁钉杆过渡配合交锁髓内钉应运而生。 目的：观察新设计的锁孔和锁钉杆直径过渡配合交锁髓内钉和传统交锁髓内钉固定骨折稳定性的比较。 方法：应用8具两侧股骨骨折标本,分别采用8根锁孔和锁钉杆直径过渡配合交锁髓内钉和传统交锁髓内钉固定骨折断端。实验组应用定制髓内钉远端瞄准微调装置配套安装器械锁钉,使用定制的直径   4.3 mm锁钉交锁固定;对照组应用常规的配套安装器械,常规的直径4.0 mm锁钉交锁固定,给予两组股骨固定标本,分别记录测量两组股骨骨折断端左右、前后、旋转移位情况,来进行骨折固定稳定性比较。 结果与结论：锁钉杆过渡配合髓内钉固定股骨中下段骨折,在10 N受力的情况下,股骨骨折断端平均有左右移位1.22 mm、前后移位1.2 mm、旋转移位0.33 mm;传统交锁髓内钉锁孔在10 N受力的情况下,股骨骨折断端平均有左右移位3.26 mm、前后移位3.37 mm、旋转移位2.15 mm,锁钉杆过渡配合髓内钉固定股骨骨折,骨折断端左右、前后、旋转移位明显小于传统交锁髓内钉,有显著性差异。说明锁孔和锁钉杆直径过渡配合交锁髓内钉置入内固定可明显提高骨折断端的稳定性。