Toxic tau: structural origins of tau aggregation in Alzheimer's disease

Alzheimer’s disease is characterized by the extracellular accumulation of the amyloidβin the form of amyloid plaques and the intracellular deposition of the microtubule-associated protein tau in the form of neurofibrillary tangles.Most of the Alzheimer’s drugs targeting amyloidβhave been failed in clinical trials.Particularly,tau pathology connects greatly in the pathogenesis of Alzheimer’s disease.Tau protein enhances the stabilization of microtubules that leads to the appropriate function of the neuron.Changes in the quantity or the conformation of tau protein could affect its function as a microtubules stabilizer and some of the processes wherein it is involved.The molecular mechanisms leading to the accumulation of tau are principally signified by numerous posttranslational modifications that change its conformation and structural state.Therefore,aberrant phosphorylation,as well as truncation of tau protein,has come into focus as significant mechanisms that make tau protein in a pathological entity.Furthermore,the shape-shifting nature of tau advocates to comprehend the progression of Alzheimer’s disease precisely.In this review,we emphasize the recent studies about the toxic and shape-shifting nature of tau in the pathogenesis of Alzheimer’s disease.     

Contemporary bone loss options: Rebuild,reinforce, and augment

Bone loss is commonly encountered during revision total knee arthroplasty (TKA). Small defects can be adequately managed with cement filling (with or without screws), modular prosthetic augments, and morselized allograft. For larger defects, cancellous impaction grafting and structural allografts have traditionally been utilized. More recently, highly porous tantalum cones and titanium sleeves have been designed to achieve axial and rotational stability in the metaphysis and subsequent biologic fixation. Sleeves are linked to one type of prosthesis, whereas cones are unlinked and can be used with any implant design. Multiple studies have demonstrated excellent survivorship and radiographic osseointegration at mid-term follow-up. This article provides a review of contemporary methods of bone loss management with a focus on highly porous metals and an emphasis on the authors’ preferred method for managing the severe bone loss in revision TKA.     

Polyethylene in knee arthroplasty: A review

Polyethylene (PE) has been used extensively in knee arthroplasty since the mid 20th century. Progress in material manufacturing and processing has led to newer polyethylenes over last few decades with different material properties. It has been established that PE wear in knee arthroplasty causes particle induced osteolysis which is the main reason for late failure and requires revision surgery. Although there are various causes of wear, the properties of PE have long been a matter of investigation as a contributory factor. The advent of newer highly cross linked PE has been shown to improve wear rates in hip arthroplasty but the benefits have not been shown to be of the same degree in knee arthroplasty. The laboratory and clinical studies so far are limited and slightly conflicting in their conclusions. The risks of using highly cross linked PE in knee arthroplasty include tibial post fracture, disruption of locking mechanism, liner fracture which can lead to increased wear and osteolysis. The current evidence suggests that highly cross linked polyethylenes should be used with caution and only considered in younger active patients. The results of a recently completed randomized trial to compare the conventional with high molecular weight PE in knee arthroplasty are awaited.     

Gastro-oesophageal reflux in children: surgical management

Gastro-oesophageal reflux disease (GORD) is symptomatic reflux of gastric contents into the oesophagus. Factors predisposing to GORD are loss of the physiological antireflux barrier and anatomic abnormalities of the oesophagus or diaphragm. Conservative measures and medical management results in resolution of symptoms in a majority of children. Surgery is indicated in the event of failure of medical management or severe complications. Surgical procedures include open or laparoscopic fundoplication in children with normal neurology; fundoplication with or without vagotomy and pyloroplasty; surgical feeding jejunostomy and oesophago-gastric dissociation in the severely neurologically impaired children.     

Mimengosides J and K: two new neuroprotective triterpenoids from the fruits of Buddleja lindleyana

Two new 11-methoxyl substituted triterpenoids, named as mimengosides J (1) and K (2), along with seven known compounds, were isolated from the fruits of Buddleja lindleyana. Their structures were elucidated on the basis of spectroscopic analysis. In addition, the new ones were evaluated for protective effects against damage of SH-SY5Y cells induced by 1-methyl-4-phenylpyridinium ion (MPP⁺) and the results indicated that those may be one of the candidate compositions of Buddleja lindleyana for the treatment of neurodegenerative disease.

     

IFI 30、PD-L1在人脑胶质瘤中的表达及与病人预后的关系

目的 探讨γ干扰素诱导蛋白30（IFI 30）、程序性死亡因子配体1（PD-L1）在人脑胶质瘤中的表达及与病人预后的关系。方法 选择2015年5月~2019年5月手术切除的103例人脑胶质瘤组织和瘤旁组织，采用免疫组织化学染色检测IFI 30、PD-L1表达情况。随访24个月，记录无进展生存期和总生存期。结果 胶质瘤组织IFI 30、PD-L1高表达率[分别为70.87%（73/103）、68.93%（71/103）]明显高于瘤旁组织[分别为19.42%（20/103）、21.36%（22/103）；P<0.001]。胶质瘤组织IFI 30表达水平与PD-L1表达水平呈明显正相关（r=0.583，P<0.05）。随访24个月，生存75例，死亡28例；多因素logistic回归分析显示，IFI 30高表达、PD-L1高表达是增加病人死亡风险的独立危险因素（P<0.05）。生存曲线分析显示，IFI 30高表达组2年累积生存率（64.52%）和2年累积无进展生存率（65.56%）均明显低于低表达组（分别为82.25%、89.45%；P<0.05）。PD-L1高表达组2年累积生存率（61.78%）和2年累积无进展生存率（60.14%）均明显低于低表达组（分别为88.52%、79.86%；P<0.05）。结论 人脑胶质瘤组织IFI 30、PD-L1呈高表达，与病人不良预后密切相关。