Faulty splicing and cytoskeleton abnormalities in Huntington's disease

Huntington's disease (HD) is caused by a CAG‐repeat encoding a polyglutamine (polyQ) tract in the huntingtin protein. There is plenty of evidence of polyQ‐driven toxicity. However, CAG repeat RNA‐driven alteration of splicing has recently been proposed in analogy to CUG‐repeat diseases. Here we review the reported alteration of the CAG‐repeat associated splicing factor SRSF6 in brains of HD patients and mouse models and how this correlates with altered splicing of, at least, two microtubule‐associated proteins in HD, namely MAPT (tau) and MAP2. Regarding tau, altered splicing of exon 10 has been reported, along with increased levels and 4R/3R‐tau ratio and detection of tau in a new nuclear rod‐shaped histopathological hallmark termed tau nuclear rod (TNR) or tau nuclear indentation (TNI). These findings, together with an attenuation of HD phenotype in R6/1 mice with tau deficiency and subsequent studies showing increased phosphorylation in mouse models and increased levels in CSF of patients, has led to proposing HD as a tauopathy. Regarding MAP2, an increase in its juvenile form and a decrease in total MAP2 together with redistribution from dendrites to soma is observed in HD patients, which may contribute to the dendritic atrophy in HD. Furthermore, MAP2 positive structures filling nuclear indentations have occasionally been found and co‐localized with tau. Therefore, altered MAP function with imbalance in tau/MAP2 content could contribute to HD striatal atrophy and dysfunction. Besides, TNIs might be indicative of such MAP abnormalities. TNIs are also found in early pathology Alzheimer's disease and in tauopathy mice over‐expressing mutant 4R‐tau. This indicates that tau alteration is sufficient for TNI detection, which becomes a marker of increased total tau and/or altered 4R/3R‐tau ratio and reporter of pathology‐associated nuclear indentations. Altogether, these recent studies suggest that correcting the SRSF6‐driven missplicing and/or microtubule‐associated imbalance might be of therapeutic value in HD.     

Analysis of ABCA4 in mixed Spanish families segregating different retinal dystrophies

Genotype-phenotype correlations highlighted the function of ABCA4 in retinitis pigmentosa (RP),cone-rod dystrophy (CRD) and Stargardt/Fundus Flavimaculatus disease (STGD/FFM). Initial screening of ABCA4 variants showed a correlation between the type of mutation and the severity of the disease. In the present study we have undertaken mutational and haplotype analysis of ABCA4 in three mixed pedigrees segregating different retinal dystrophies. In family I, we have shown cosegregation of different ABCA4 alleles with CRD (homozygosity for L1940P) and three subtypes of STGD/FFM. The first, a mild form, consisting on fundus flavimaculatus-like distribution of flecks, but good visual acuity and absence of dark choroid, was found to cosegregate with alleles R1097C and F553L; the second, a conventional Stargardt phenotype was associated to alleles L1940P/R1097C and the third, displaying severely reduced visual acuity and dark choroid (named FFM), was associated to L1940P/F553L. In family II, segregating STGD and RP phenotypes, while the involvement of ABCA4 in STGD seems clear this is not the case for RP. Finally, in family III, also segregating STGD and RP, ABCA4 fails to explain either phenotype. Our data highlight the wide allelic heterogeneity involving this gene and support the genetic variability (beyond ABCA4) of mixed STGD/RP pedigrees.     

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。     

可吸收棒或钛合金螺钉治疗MasonⅡ型桡骨头骨折的疗效

文题释义：可吸收棒、钛合金螺钉内固定：两者均属于MasonⅡ型桡骨头骨折螺钉内固定法,主要区别在于其制作材质不一样,前者是由聚乳酸制成的可吸收高分子聚合物,而后者为钛合金制成,需二次手术取出。桡骨头骨折Mason分类：Ⅰ型,为线状骨折,即无移位型骨折,骨折线可通过桡骨头边缘或呈劈裂状;Ⅱ型,为有移位的骨折,有分离的边缘骨折;Ⅲ型,为粉碎型骨折,移位或无移位或呈塌陷性骨折;Ⅳ型,为桡骨头骨折伴有肘关节脱位。背景：目前切开复位内固定是治疗MasonⅡ型桡骨头骨折的有效方法,内固定的选择有螺钉、微型钢板、克氏针、可吸收棒或钉等,临床疗效报道不一致。目的：对比可吸收棒或钛合金螺钉内固定治疗MasonⅡ型桡骨头骨折的临床疗效。方法：选择2016年1月至2017年2月四川省人民医院收治的桡骨头骨折患者25例,其中男16例,女9例,年龄38-61岁,均进行切开复位内固定治疗,其中13例的内固定材料为钛合金螺钉,另12例的内固定材料为可吸收棒。术后随访拍摄X射线片,确定骨折愈合时间。末次随访时,对比两组目测类比评分、肘关节活动度及肘关节功能Mayo评分与Broberg-Morrey 评分。该研究已通过四川省医学科学院·四川省人民医院伦理委员会的审批。结果与结论：①可吸收棒组、钛合金螺钉组的骨折愈合时间分别为(2.35±0.92),(2.10±0.47)个月,组间比较差异无显著性意义(P > 0.05);②末次随访时,两组间肘关节功能Mayo评分与Broberg-Morrey 评分比较差异均无显著性意义(P > 0.05);③末次随访时,两组间肘关节屈曲、伸直、旋后、旋前角度比较差异均无显著性意义(P > 0.05);④末次随访时,两组目测类比评分比较差异均无显著性意义(P > 0.05);⑤结果表明,可吸收棒与钛合金螺钉治疗MasonⅡ型桡骨头骨折的临床疗效相似,但可吸收棒避免了二次手术取出内固定及应力性遮挡等情况。ORCID: 0000-0003-4778-7050(杨晓)中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Tau‐positive nuclear indentations in P301S tauopathy mice

Increased incidence of neuronal nuclear indentations is a well‐known feature of the striatum of Huntington's disease (HD) brains and, in Alzheimer's disease (AD), neuronal nuclear indentations have recently been reported to correlate with neurotoxicity caused by improper cytoskeletal/nucleoskeletal coupling. Initial detection of rod‐shaped tau immunostaining in nuclei of cortical and striatal neurons of HD brains and in hippocampal neurons of early Braak stage AD led us to coin the term “tau nuclear rods (TNRs).” Although TNRs traverse nuclear space, they in fact occupy narrow cytoplasmic extensions that fill indentations of the nuclear envelope and we will here refer to this histological hallmark as Tau‐immunopositive nuclear indentations (TNIs). We reasoned that TNI formation is likely secondary to tau alterations as TNI detection in HD correlates with an increase in total tau, particularly of the isoforms with four tubulin binding repeats (4R‐tau). Here we analyze transgenic mice that overexpress human 4R‐tau with a frontotemporal lobar degeneration‐tau point mutation (P301S mice) to explore whether tau alteration is sufficient for TNI formation. Immunohistochemistry with various tau antibodies, immunoelectron microscopy and double tau‐immunofluorescence/DAPI‐nuclear counterstaining confirmed that excess 4R‐tau in P301S mice is sufficient for the detection of abundant TNIs that fill nuclear indentations. Interestingly, this does not correlate with an increase in the number of nuclear indentations, thus suggesting that excess total tau or an isoform imbalance in favor of 4R‐tau facilitates tau detection inside preexisting nuclear indentations but does not induce formation of the latter. In summary, here we demonstrate that tau alteration is sufficient for TNI detection and our results suggest that the neuropathological finding of TNIs becomes a possible indicator of increased total tau and/or increased 4R/3R‐tau ratio in the affected neurons apart from being an efficient way to monitor pathology‐associated nuclear indentations.     

表面改性TiNi记忆合金棒的回复力学实验研究

采用直径为6~7 mm钛铌涂层T iN i记忆合金棒与未经表面改性的T iN i记忆合金棒,相变温度平均为33.0℃,低温下在三点弯卡具上进行预弯,挠度分别为5.0、10.0、15.0和20.0 mm,保持位移恒定,分别在37℃及50℃的生理盐水溶液恒温水浴箱中测量其三点弯回复力变化特性。结果表明,T iN i记忆合金棒的回复力随回复温度、棒直径、变形量增加而增加;经钛铌表面喷涂后6 mm及6.5 mm棒的回复力有一定降低,但7 mm棒回复力没有显著性差异。依照以上数据可以为临床设计脊柱侧弯矫形棒提供参考。     

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.     

改良杆卡式附着体与不同可摘局部义齿对支持组织应力分布的研究

目的探讨改良杆卡式附着体义齿与RPI卡环组、联合卡环组可摘局部义齿修复单侧游离缺失对支持组织的应力分布。方法在下颌47、46单侧游离缺失的环氧树脂模型上分别以改良杆卡式附着体、RPI卡环组、联合卡环组3种固位形式的可摘义齿修复,用三维光弹应力冻结切片技术测试义齿加载后对基牙和缺牙区牙槽骨应力分布。结果对基牙牙槽骨的应力：改良杆卡式附着体义齿〉RPI卡环组〉联合卡环组（P〈0．05）;附着体义齿对基牙的近、远中应力无显著性：差异（P〉0．05）;RPI卡环组义齿有猞支托处的应力大于无拾支托处的应力（P〈0．05）;联合卡环组对远中的应力大于近中（P〈0．05）。对缺牙区牙槽骨应力：改良杆卡式附着体与RPI卡环组均小于联合卡环组（P〈0．05）;附着体义齿、RPI对缺牙区牙从近中到远中的4个切片应力无显著性差异（P〉0．05）,联合卡环组远中大于近中（P〈0．05）。结论改良杆卡式附着体义齿有应力中断作用,各点应力分布较均匀。RPI固位的活动义齿应力主要分布在基牙上,缺牙区应力稍小。联合卡环组义齿对失牙区的应力最大,基牙上应力较小。     

视蛋白基因启动子的克隆和鉴定

目的 克隆出视蛋白基因启动子。方法 以小鼠全基因组为模板，用PCR法克隆出目的大小的片断。然后连接到T-载体上作酶切鉴定，最后测序。结果 酶切结果与预期相符，测序结果与公布序列完全一致。结论 视蛋白基因启动子克隆成功。