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.     

综述三维斑点追踪技术在糖尿病心肌病心功能评价中的应用

糖尿病心肌病(Diabetic Cardiomyopathy,DC)的进展会导致左心室功能减低,因此,早期正确评估左心室功能对糖尿病心肌病患者的治疗和预后有着重要的意义。由于左心室解剖结构的复杂性,常规超声技术通常很难准确的评估左心室功能的变化,三维斑点追踪技术(three-dimensional speckle tracking imaging,3D-STI)是在实时3D超声和斑点追踪技术(STI)基础上发展起来的一项新技术,其对心脏功能的评估不受整个心脏运动方向和运动幅度的限制,能够直观的对心肌各个方向的运动进行追踪。本文首先论述3D-STI 在左心室功能评价中的可行性,再对其在DC左心室功能评价中的研究展开综述。     

基于多元统计分析和网络药理学的五味子醋制前后质量标志物预测分析

目的基于多元统计分析和网络药理学分析预测五味子醋制前后潜在的质量标志物。方法采用UPLC-Q/TOF-MS解析生、醋五味子饮片中主要的木脂素类成分,并运用多元统计方法筛选出炮制前后潜在的差异化学成分,即化学标记物。进一步通过网络药理学以及生物信息学分析显著差异成分相关的主要作用靶点和通路,构建"成分-靶点-通路"网络关系,预测生、醋五味子潜在的质量标志物。结果筛选了五味子醋制前后差异性成分40个,其中8个为生、醋五味子之间显著性差异成分(即化学标记物)。鉴定并确认了其中的5个化学成分,分别是5-羟甲基糠醛、五味子甲素及其同分异构体、五味子乙素和五味子酯丁。而其余3个化学标记物通过解析一级、二级质谱信息,推测它们很可能也属于木脂素类成分。网络药理学分析结果表明,鉴定并确认的5个潜在质量标志物与五味子的主要药理作用密切相关。最终五味子乙素和5-羟甲基糠醛被确定为最具代表性的潜在质量标志物。结论五味子醋制前后其化学成分发生了一系列复杂的变化,经研究分析确定五味子乙素和5-羟甲基糠醛可作为五味子醋制前后代表性的潜在质量标志物,并推测木脂素类成分可能为五味子醋制保肝的重要效应物质基础。     

Serum TLR2 and TLR4 levels in colorectal cancer and their association with systemic inflammatory markers,tumor characteristics,and disease outcome

Toll‐like receptors (TLRs) are involved in colorectal cancer (CRC) pathogenesis. However, the significance of serum TLR concentrations in CRC is unknown. We analyzed serum TLR2 and TLR4 concentrations with ELISA in preoperative samples from 118 patients with CRC and 88 matched controls. We also assessed tissue TLR expression with immunohistochemistry and by detecting serum determinants of systemic inflammation. Most participants (>70%) had undetectable serum TLR2. The mean serum TLR4 levels were lower in patients than in controls (1.1 vs 1.8 ng/mL; p = 0.015). Undetectable TLR4 was more common in stage I (39%) than in stages II–IV (11%, p < 0.001). TLR2 or TLR4 expression in tumor cells did not correlate with serum levels, but abundant TLR2 expression in normal colon epithelium was associated with detectable serum TLR2 (p = 0.034). Undetectable serum TLR2 was linked to high modified Glasgow prognostic scores (p = 0.010), high CRP levels (p = 0.013), blood vessel invasion (p = 0.013), and tended to be associated with worse 5‐year survival (p = 0.052). In conclusion, serum TLR2 levels were inversely associated with systemic inflammation in patients with CRC. Moreover, serum TLR2 levels might depend more on normal colorectal mucosa contributions than on tumor tissue contributions. Further studies are required to assess the prognostic value of serum TLR2.     

Effect of single‐dose injection of vitamin D on immune cytokines in ulcerative colitis patients: a randomized placebo‐controlled trial

Ulcerative colitis (UC) is a chronic recurrent inflammation of the colon. It has been proposed that the UC pathogenesis may be related to vitamin D deficiency and/or vitamin D administration in UC patients may have an ameliorating effect on the intestinal inflammation. The aim of this study was to assess the effect of vitamin D on the serum levels of immune cytokines in UC patients. In this double‐blind randomized controlled trial, 90 mild‐to‐moderate UC patients were assigned to get either a single muscular injection of 7.5 mg vitamin D3 or 1 mL normal saline as placebo. Three months later serum levels of IL‐4, IL‐10, IL‐12p70, IFN‐γ, and TNF‐α were measured. Two group variables were compared using independent t‐test and analysis of covariance (ANCOVA). There was a significant increase in vitamin D only in the vitamin D group. Compared to placebo, vitamin D had significant decreasing effects on serum TNF‐α, IFN‐γ, and IL12p70 levels, but it had no significant effect on serum levels of IL4 and IL10. Vitamin D seems to inhibit Th1 immune responses and have no effect on Th2 responses. The findings of this study support several in vitro studies, which suggest a therapeutic immunomodulatory potential of vitamin D.     

Hypovitaminosis D in patients with osteoporotic hip fractures

BackgroundInadequate serum vitamin D levels are associated with secondary hyperparathyroidism, increased bone turnover, bone loss and increased fracture risk. Vitamin D is well recognized to be suboptimal in older patients when compared to age-matched controls. There are no published studies on the prevalence of hypovitaminosis D in Indian population with fragility fractures around the hip associated with osteoporosis and comminution at the fracture site.AimTo investigate the prevalence of hypovitaminosis D in patients admitted with osteoporotic hip fractures and associated fracture site comminution in a South Indian Institute.Material & MethodsA prospective cross sectional study was conducted on 100 patients admitted with osteoporotic hip fracture. Measurement of serum 25-hydroxy vitamin D was done and the same was correlated with the degree of osteoporosis using Singh’s index and fracture site comminution.ResultsOut of 100 patients studied, 92% had hypovitaminosis D with mean vitamin D level of 16.08 ± 5.95 ng/dl (65% vitamin D deficiency with mean 13.16 ± 4.24 ng/dl and 27% vitamin D insufficiency with mean 23.11 ± 2.62 ng/dl) and 94% had osteoporosis with Singh’s index grade 3 or less. Out of the 36 patients with fracture site comminution 34 patients (94%) had hypovitaminosis D and 33 patients (91.6%) had osteoporosis. Statistical significance was established for all the variables.ConclusionSignificant association was found between hypovitaminosis D, osteoporosis and fracture site comminution. High prevalence of hypovitaminosis D in patients presenting with hip fractures and fracture site comminution implicates the necessity for proper evaluation and effective supplementation of vitamin D in elderly patients along with anti-osteoporotic regimens for effective prevention and appropriate management of osteoporotic hip fractures.     

Clinical Course of Patients With Worsening Heart Failure With Reduced Ejection Fraction

Background

Epidemiology of patients with worsening heart failure and reduced ejection fraction (HFrEF) in the real-world setting is not well described.

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.