Preoperative Ozaki technique measures on tridimensional engineered root

BackgroundThe aortic valve neocuspidalization (AVNeo) is an innovative surgical technique aiming at the reconstruction of the aortic valve using autologous pericardium. One of the main criticisms to AVNeo is the longer duration of the aortic clamping time (ACT) as compared to standard aortic valve replacement due to the sizing of the valve neocusps.MethodsWe retrospectively enrolled 30 consecutives patients underwent AVNeo. For each patient we developed a 3D aortic root model (ARM) based on CT-scan datasets. We retrospectively compared the leaflets measurements performed during surgery with those obtained on the corresponding ARMs.ResultsIn 100% of cases no difference between the in vitro and in vivo measurements exceeded the acceptable error limit of 2 ?mm. The correlation of each single in vitro versus in vivo measurements demonstrates a strong coincidence between the two different methods of sizing (r ?> ?0,9, p ?< ?.0001). By analyzing the data considering the annulus perimeter and not the single cusp size, the perfect coincidence was to be found in 89.9% with a slight acceptable discrepancy (2 ?mm on total) in the remaining 10.1%.Conclusions3D-ARMs, printed from CT-scan, represent a reproducible process to obtain overlapping cusp sizes compared to those measured in-vivo, possibly reducing the ACT.     

3D打印可拆卸垂体瘤切除模型的真实性评估

目的探究可拆卸经鼻垂体腺瘤切除操作模型的真实性,并初步探讨了模型的教学性。方法利用患者CT建模、精细优化及3D打印技术构建可拆卸垂体腺瘤切除模型。评估者为19名来自北京协和医院的本院及进修医师,其中年资<10分入"低年资组";年资≥10分入"高年资组"。每位医师分别对3D打印垂体腺瘤切除模型进行操作,并于操作前后分别填写调查问卷、评估量表。结果高年资组的探查经验均高于低年资组。真实度项目的得分均在4附近,各评分项间无明显差异;"切除垂体腺瘤"步骤的真实性评分相对较低;高年资组评分普遍低于低年资组。操作前低年资组信心评分显著低于高年资组,操作后两组评分趋于一致;低年资组的垂体腺瘤切除信心评分变化显著高于高年资组(P<0.05)。结论该模型具有较高的真实性,可用于教学试验进一步评估教学效果。     

夏枯草、黄芩、钩藤治疗肝热型高血压病经验--仝小林三味小方撷萃

仝小林教授将高血压病分为"三期六态",指出热壅态中的肝热证具有"四红二干"的临床表现,"四红"指面(目)红、唇红、舌红、掌红,"二干"指便干、口干。常处以靶方夏枯草、黄芩、钩藤清肝降压,一般用量为夏枯草30~60 g,黄芩15~30 g,钩藤15~30 g,根据兼证配合使用清热、降火、散火、行气、利湿之品。该小方治疗肝热型高血压病时,降压效果显著,并可以明显减轻头晕、头痛、目赤等症状,临床疗效良好,但需注意不可长期大剂量使用。     

Three-body wear of 3D printed temporary materials

ObjectiveThe aim of this study was to investigate the three-body wear of different additively manufactured temporary materials, one temporary PMMA material for CAD/CAM milling and one resin-based composite for direct restorations as a control group by using an ACTA machine.MethodsSpecimens (n = 8) of the 3D printing materials 3Delta temp, NextDent C&B, Freeprint temp were additively manufactured by DLP 3D printer. Postprocessing was carried out according to the manufacturer's specifications. Telio CAD were cut out of blocks, Tetric EvoCeram was applied directly and light cured. Three-body wear was simulated with an ACTA machine. Data were statistically analysed (ANOVA, post hoc test: Tukey, p < 0.05). The worn surfaces of the specimens were examined with a FE-SEM.ResultsThe average mean wear was 50 ± 15 μm for Tetric EvoCeram < 62 ± 4 μm for 3Delta temp < 236 ± 31 μm for Telio CAD < 255 ± 13 μm for NextDent C&B < 257 ± 24 μm for Freeprint temp. After 200,000 cycles, the wear and wear rates for Tetric EvoCeram and 3Delta temp were significantly lower than those for the other materials. SEM revealed that 3Delta temp has a higher filler proportion than the other 3D printing materials but less than Tetric EvoCeram.SignificanceThe filler content influences the wear behaviour of additively manufactured materials as well as dental restorative composite materials. While most 3D printing materials have a low inorganic filler load, which qualifies the materials for temporary use only, one 3D printing material has an optimized composition that would qualify the material for longer clinical service time if wear is considered as the outcome variable.     

Avian mud nest architecture by self-secreted saliva

Mud nests built by swallows (Hirundinidae) and phoebes (Sayornis) are stable granular piles attached to cliffs, walls, or ceilings. Although these birds have been observed to mix saliva with incohesive mud granules, how such biopolymer solutions provide the nest with sufficient strength to support the weight of the residents as well as its own remains elusive. Here, we elucidate the mechanism of strong granular cohesion by the viscoelastic paste of bird saliva through a combination of theoretical analysis and experimental measurements in both natural and artificial nests. Our mathematical model considering the mechanics of mud nest construction allows us to explain the biological observation that all mud-nesting bird species should be lightweight.

Bird nests come in a variety of forms made from diverse building materials (1, 2). Each type of bird nest is subjected to mechanical constraints imposed by material characteristics. To overcome these constraints, birds have devised brilliant architectural technologies, which provide inspiration for a novel materials processing scheme and help us to better understand animal behavior.For instance, some birds including storks (Cicioniidae) and eagles (Accipitidae) build nests by piling up hard filamentary materials such as twigs, harnessing their friction as the cohesion mechanism (3). Weaverbirds (Ploceidae) weave soft filamentary materials such as grass and fine leaves into a woven nest tied to a tree branch. Some bird species use their own saliva in nest building, which Darwin considered an example of natural selection (4). An extreme case is the Edible-nest Swiftlets, which build their nest purely of self-secreted saliva so that it can be attached to cliff walls and cave ceilings where the above twig piles and tied leaves are not allowed (5).Swallows (Hirundinidae), phoebes (Sayornis), and other mud nesters have developed a unique building material, a mixture of mud and their own saliva, in contrast to those made of purely collected or self-secreted materials (6) (Fig. 1). During construction, mud nesters repeatedly pile a beakful of wet mud on the nest, and liquid bridges are formed in the nest due to evaporation. While building a nest usually takes several weeks, a transition from wet to dry structures can occur within a few hours. Hence, the capillary forces of liquid bridges temporarily provide cohesion such as those in sandcastles. However, unlike sandcastles, dehydrated saliva comes into play for permanent cohesion after complete evaporation (SI Appendix, Supplementary Note 1).Open in a separate windowFig. 1.A nest of the barn swallow (H. rustica). (A) Photograph of a barn swallow nest, taken from under the ceiling of a house in Suwon-si, Gyunggi-do, South Korea (37°16′13.5″N 126°59′01.0″E). (B) SEM image of the nest surface. (C) Chemical composition analysis of the surface shown in B by EDS. The red area indicates a region containing mostly carbon atoms, which may originate from bird saliva. The green area indicates a region containing mostly the silicon atoms of clay particles.Mud itself cannot confer sufficient cohesion and adhesion in mud nests. The ability of mud nests to bear tensile loads originates from the gluing agent in the bird''s saliva, which permeates into granules as a liquid and binds them as a solid after solvent evaporation (6–8) (SI Appendix, Supplementary Note 2). The gluing agent is called mucin, a family of large glycoproteins that are ubiquitous in animal organs and form a mucus gel with versatile functionality (9). Fig. 1B shows the scanning electron microscopy (SEM) image of a barn swallow’s mud nest consisting of platelet clay particles and larger grains. Energy-dispersive spectroscopy (EDS) mapping image of Fig. 1C clearly shows regions corresponding to organic material which is presumed to be from bird’s saliva.Of particular interest and worth biophysical investigation are the tensile strength of the mud nest with hardened saliva, design principles associated with the saliva-originated strength, and the resulting effects on the evolution of these mud-nesting birds. Principles behind cohesion in granular materials, such as wet sands (10), cemented powder aggregates (11), construction materials (12), and pharmaceutical tablets (13), have been studied to date, exploring the stress transmission, elasticity, and failure (14–18), and the formation of solidified bridges (19–21). However, little attention has been paid to the cohesion effects of self-secreted polymer materials upon evaporation and the biologically constructed granular architecture like birds’ mud nests. Here we devised experimental techniques to measure the strength of the relatively small and fragile nest specimens in order to mechanically characterize birds’ mud nests. We elucidate how solutes from bird saliva generate solid bridges that give rise to macroscopic tensile strength, which has long awaited physicochemical explanation since its first observation (4). To characterize the design principle of bird''s mud nests, we investigated natural and three-dimensional (3D)-printed artificial nests with various tools for visualization and mechanical testing. Along with the experimental studies, we theoretically investigated the effects of biopolymer concentration on nest strength. This combination of theory and experiment suggests that there is a size limit for mud-nesting birds, which is supported by biological data.     

Mixed Reality Combined with Three‐Dimensional Printing Technology in Total Hip Arthroplasty: An Updated Review with a Preliminary Case Presentation

Three‐dimensional (3D) printing technology, virtual reality, and augmented reality technology have been used to help surgeons to complete complex total hip arthroplasty, while their respective shortcomings limit their further application. With the development of technology, mixed reality (MR) technology has been applied to improve the success rate of complicated hip arthroplasty because of its unique advantages. We presented a case of a 59‐year‐old man with an intertrochanteric fracture in the left femur, who had received a prior left hip fusion. After admission to our hospital, a left total hip arthroplasty was performed on the patient using a combination of MR technology and 3D printing technology. Before surgery, 3D reconstruction of a certain bony landmark exposed in the surgical area was first performed. Then a veneer part was designed according to the bony landmark and connected to a reference registration landmark outside the body through a connecting rod. After that, the series of parts were made into a holistic reference registration instrument using 3D printing technology, and the patient's data for bone and surrounding tissue, along with digital 3D information of the reference registration instrument, were imported into the head‐mounted display (HMD). During the operation, the disinfected reference registration instrument was installed on the selected bony landmark, and then the automatic real‐time registration was realized by HMD through recognizing the registration landmark on the reference registration instrument, whereby the patient's virtual bone and other anatomical structures were quickly and accurately superimposed on the real body of the patient. To the best of our knowledge, this is the first report to use MR combined with 3D printing technology in total hip arthroplasty.     

Bands of Fontana are caused exclusively by the sinusoidal path of axons in peripheral nerves and predict axon path; evidence from rodent nerves and physical models

The precise cause of the bands of Fontana, striations on peripheral nerves visible to the naked eye, has been the subject of debate for hundreds of years. Some researchers have described them as reflecting the sinuous course of nerve fibres passing through nerves, and others have proposed that endoneurial collagen and sheaths surrounding nerves play a role in their appearance. We hypothesised that the bands are caused exclusively by reflection of light from the surfaces of nerve fibres travelling in phase in sinusoidal waveforms through peripheral nerves. We aligned images of obliquely illuminated nerves with confocal images of axons in those nerves, and the numbers and positions of the bands precisely matched the axonal waves. We also developed three‐dimensional models of nerves with representations of the sinusoidal path of axons at their surface. We observed patterns resembling the bands of Fontana when these models were obliquely illuminated. This provides evidence that the bands of Fontana can be caused by light reflected sinusoidal path of axons alone. We subsequently describe a mechanism of band production based on our observations of both nerves and models. We report that smaller diameter nerves such as phrenic nerves and distal branches of sciatic nerves have shorter band intervals than larger nerves, such as proximal trunks of sciatic nerves, and that shorter band intervals correlate with longer axons per unit length of nerve, which suggests a greater tolerance to stretch. Inspection of banding patterns on peripheral nerves may permit prediction of axon length within nerves, and assist in the interpretation of nerve conduction data, especially in diseases where axon path has become altered.