The pulmonary deposition and retention of indium-111 labeled ultrafine carbon particles in healthy individuals

Context: Particulate air pollution, for example, from ultrafine (UF) particles, has negative health effects. However, there is still limited knowledge regarding the fate of inhaled particles in the human body.

Objectives: To describe the normal lung deposition and 1 week particle retention of indium-111 labeled UF carbon particles in healthy subjects. Additionally, the possibility to extend the follow-up period to 4 weeks was also investigated for one of the subjects.

Results: The cumulative pulmonary particle clearance 1 week post-administration, corrected for activity leaching and mucocilliary transport of activity deposited in the central airways, was 4.3?±?8.5% (average ± standard deviation at group level), with marginal translocation of particles from lungs to blood, 0.3%. There was no observable elimination of particles from the body via urine. Seven days after exposure, the cumulated activity leaching was 3% (group level), which indicates a stable bonding between the particles and Indium-111. The volunteer followed for a total of 4 weeks, showed a cumulative decrease of activity retention in the lungs of 10.5%. After correction for activity leaching and clearance from central airway deposition, the estimated particle clearance was about 2%.

Conclusions: No evidence for particle translocation from the lungs could be proven 7 days after exposure. It is possible to follow-up Indium-111 labeled UF carbon particles at least 1 month post-administration without increasing the administered activity.     

Compressive Properties and Energy Absorption Characteristics of Extruded Mg-Al-Ca-Mn Alloy at Various High Strain Rates

This paper is focused on the mechanical properties and the energy absorption characteristics of the extruded Mg-Al-Ca-Mn alloy in different compression directions under high strain rate compression. Compressive characterization of the alloy was conducted from the high strain rate (HSR) test by using a Split Hopkinson Pressure Bar (SHPB). Results show that the investigated alloy exhibits a strong strain rate sensitivity. With the rise of strain rate, the compressive strength is increased significantly, and the deformation ability also improves. When compressed along the extrusion direction, as the strain rate increases, the total absorbed energy E, the crush force efficiency (CFE), and the specific energy absorption SEA of Mg-Al-Ca-Mn alloy are all greatly improved as compared with those obtained along other compression directions.     

形状记忆合金弓齿钉治疗腕舟状骨腰部骨折

正2013年10月~2015年3月,我科采用腕掌侧切开复位形状记忆合金弓齿钉治疗17例腕舟状骨腰部骨折患者,疗效满意,报道如下。1材料与方法1.1病例资料本组17例,男15例,女2例,年龄16~42岁。左侧1例,右侧16例,均为闭合骨折。新鲜骨折16例,陈旧性骨折1例,合并桡骨茎突骨折1例。1.2治疗方法臂丛麻醉下手术。取     

Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits: A biomechanical study

BACKGROUNDToday, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads.AIMTo compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits.METHODSThe study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet''s Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred.RESULTSThe breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly (P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM (P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 (P = 0.001).CONCLUSIONTANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration (P = 0.001) in healthy and in osteoporotic bone.     

Nano-TiO2 particles impair adhesion of airway epithelial cells to fibronectin

Titanium dioxide engineered nanoparticles (nano-TiO₂) are widely used in the manufacturing of a number of products. Due to their size (<100 nm), when inhaled they may be deposited in the distal lung regions and damage Clara cells. We investigated the mechanisms by which short-term (1-h) incubation of human airway Clara-like (H441) cells to nano-TiO₂ (6 nm in diameter) alters the ability of H441 cells to adhere to extracellular matrix. Our results show that 1 h post-incubation, there was a 3-fold increase of extracellular H₂O₂, increased intracellular oxidative stress as demonstrated by 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) oxidation, and a 5-fold increase of phosphor-ERK1/2 as measured by Western blotting. These changes were accompanied by a 25% decrease of H441 adherence to fibronectin (p < 0.05 compared to vehicle incubated H441 cells). Pretreatment with the ERK1/2 inhibitor U0126 for 3 h, partially prevented this effect. In conclusion, short-term exposure of H441 cells to nano-TiO₂ appears to reduce adherence to fibronectin due to oxidative stress and activation of ERK1/2.     

Titanium - castor oil based polyurethane composite foams for bone tissue engineering

Abstract

Polyurethanes (PU) foams with titanium particles (Ti) were prepared with castor oil (CO) and isophorone diisocyanate (IPDI) as polymeric matrix, and 1, 3 and 5?wt.% of Ti. Composites were physicochemically and mechanically characterized and their biocompatibility assessed using human dental pulp stem cells (HDPSC). PU synthesis was confirmed by FTIR, but the presence of Ti was detected by RAMAN, X-ray diffraction (peak at 2θ?=?40.2°) and by EDX-mapping. Materials showed three decomposition temperatures between 300?°C and 500?°C and their decomposition were not catalyzed by Ti particles. Compressive modulus (164–846?kPa), compressive strength (12.9–116.7?kPa) and density (128–240?kg/m³) tend to increase with Ti concentration but porosity was reduced (87% to 80%). Composites’ foams were fully degraded in acid and oxidative media while remained stable in distilled water. HDPSC viability on all composites was higher than 80% up to 14?days while proliferation dropped up to 60% at 21?days. Overall, these results suggest that these foams can be used as scaffolds for bone tissue regeneration.     

Influence of Oxynitrided Surface in the Production of a Less Susceptible Titanium Surface to Skin‐Borne Bacterial Adhesion

There is a growing quest for an ideal biomaterial that shows appropriate cellular response and is not susceptible to microbial adhesion. In this study, commercial grade II titanium was submitted to RF/DC plasma surface modification at 2.2 mbar, using gas mixtures of argon, nitrogen, and oxygen at proportions 4:1:2 and 4:1:3. The surfaces were physically and chemically characterized. In order to evaluate bacterial response, the surfaces were exposed to Staphylococcus epidermidis. Oxynitrided samples, although having a higher roughness as compared with untreated samples, exhibited lower bacterial growth. This observation is probably due to the formation of different crystalline phases of nitrides and oxides caused by plasma treatment. The surface with highest contact angle and highest surface tension showed lower bacterial adhesion. These results were confirmed by scanning electron microscopy. The role of nitrogen in reducing bacterial adhesion is clear when this material is compared with untreated titanium, on which only an oxide film is present.     

Cell uptake and oral absorption of titanium dioxide nanoparticles

Large efforts are invested on the development of in vitro tests to evaluate nanomaterial (NM) toxicity. In order to assess the relevance of the adverse effects identified in in vitro toxicity tests a thorough understanding of the biokinetics of NMs is critical. We used different in vitro and in vivo test methods to evaluate cell uptake and oral absorption of titanium dioxide nanoparticles (TiO₂ NPs). These NPs were readily uptaken by A549 cells (carcinomic human alveolar basal epithelial cells) in vitro. Such rapid uptake contrasted with a very low oral absorption in a differentiated Caco-2 monolayer system (human epithelial colorectal adenocarcinoma cells) and after oral gavage administration to rats. In this oral study, no significant increase in the levels of titanium was recorded by ICP-MS in any of the tissues evaluated (including among other: small intestine, Peyer's patches, mesenteric lymph nodes, liver, and spleen). No NPs were observed by TEM in sections of the small intestine, except for several particles in the cytoplasm of a cell from a Peyer's Patch area. The observation of NPs in Peyer's Patch suggests that the Caco-2 monolayer system is likely to underestimate the potential for oral absorption of NPs and that the model could be improved by including M-cells in co-culture.     

食管缺损经肺组织瓣和金属支架重建后黏膜爬行的光镜和电镜观察

 目的 探讨肺组织瓣修复食管侧壁缺损内衬金属支架的方法进行食管重建的可行性。 方法 选取成年犬12条,切除中段食管,选用右中叶肺组织作为替代物,将金属支架放置于缺损处食管内,用游离的肺组织瓣修补食管缺损。术后行钡餐透视检查及病理学检查,通过光镜和电镜观察黏膜的爬行过程,爬行的新生上皮的超微结构。结果 新生食管复层上皮与肺组织瓣连接紧密,愈合良好。但术后18周腺体和平滑肌的再生均不明显。结论 肺组织瓣内衬金属支架重建食管为食管替代提供了一种新的尝试，作为支撑物其远期效果有待进一步探讨。