Anastomotic false aneurysms with aortic Dacron graft after twenty-five years

One of the early diamond crimped knitted polyester (Dacron) grafts was surgically excised after implantation for 25 years in the aorto-billiac position because of false aneurysm formation at the three anastomotic sites. The sutures were no longer visible. While the areas around the false aneurysm were poorly incorporated, the graft limbs were well encapsulated with some endothelial-like cells on the luminal surface. The integrity of the graft was well preserved despite mild fraying and the disruption of one stitch.     

Innovation According to C. Walton Lillehei

C. Walton Lillehei (1918–1999) represents the most distinguished American surgeon of his time and perhaps the greatest surgeon in history. As his mentor, Owen H. Wangenesteen (1898–1981), so accurately declared, Walt Lillehei was “one of the surgical immortals.” Indeed, similar words were echoed by the famous cardiac surgeon, Denton A. Cooley (b. 1920), who said, “Hardly any other cardiac surgeon has introduced a greater number of innovative techniques and concepts.”

Born in Minneapolis, Lillehei attended the University of Minnesota, where he completed his college, medical, physiology, and surgical studies. Because of his extraordinary contributions to make open heart surgery feasible and safe, he is considered the father of open heart surgery. Many other contributions followed the initial innovations, particularly the use of the bubble oxygenator, the total intracardiac repair of tetralogy malformation, the use of myocardial electrodes for treating complete heart block, and the development of three cardiac valve prostheses, among other discoveries.

The noted Minnesota surgeon was an innovator for his entire professional career. He believed in innovation and practiced innovation in any way possible. “Determination, persistence, and stubbornness” were, according to Lillehei, “the most important components of research and successful discovery.”     

Poly(Ethyleneimine)‐Immobilized‐Cloth Enzyme Immunoassay for the Detection of Salmonella Lipopolysaccharide

Poly(ethyleneimine) (PEI) was immobilized on non‐woven polyester cloth and examined for application on a simple, rapid and economical “cloth enzyme immunoassay (CEIA)” which was developed originally as polymyxin‐CEIA for the detection of Salmonella lipopolysaccharide (LPS). PEI‐cloth regardless of the PEI molecular weight, but with the amine group contents of 0.1 ～ 0.35 meq/g immobilized either in a physisorption‐like or chemisorption‐like manner, adsorbed LPS rapidly, preferentially and effectively. The captured LPS was then able to be detected qualitatively and quantitatively as an antigen by enzyme immunoassay. PEI‐CEIA had a detection limit for Salmonella LPS of 10 ng/ml, which was equivalent to 1.6 × 10⁵ cell/ml and was ten times more sensitive than polymyxin‐CEIA. It was possible to detect Salmonella LPS in the presence of a 100‐fold excess of E. coli LPS. PEI‐CEIA was found to be more sensitive and much easier to carry out than polymyxin‐CEIA but had the same advantages as polymyxin‐CEIA.     

显微血管减压术中单纯应用涤纶垫棉治疗基底动脉压迫所致三叉神经痛的临床疗效

目的初步探讨显微血管减压术中单纯应用涤纶垫棉治疗基底动脉压迫所致三叉神经痛的临床疗效。方法回顾性分析2012年1月至2019年12月陆军军医大学大坪医院神经外科收治的31例基底动脉压迫引发三叉神经痛患者的临床资料。31例患者在显微血管减压术中均单纯使用涤纶垫棉作为减压材料,且未使用其他减压方式。手术采用经乙状窦后入路,于脑干和责任动脉之间放置涤纶垫棉实现减压。采用巴罗神经学研究所(BNI)提出的疼痛分级评估手术效果。结果31例三叉神经痛患者中,27例(87.1%)术后疼痛即刻完全缓解(BNI分级Ⅰ级),3例在术后3个月内完全缓解(BNI分级Ⅰ级),1例疼痛部分缓解(BNI分级Ⅲ级)。5例(16.1%)患者术后出现面部感觉减退,其中3例自愈;1例患者出现渐进性听力下降。31例患者的随访时间为6~85个月(中位时间为40个月),随访期间有4例(12.9%)复发(BNI分级Ⅳ~Ⅴ级),其中2例再次接受手术治疗,另外2例采用立体定向放射治疗配合药物治疗可部分控制面部疼痛。结论显微血管减压术中单纯应用涤纶垫棉治疗基底动脉所致三叉神经痛的术后即刻效果显著,但其复发率及并发症的发生率较高。     

Effect of polyester fiber reinforcement on the mechanical properties of interim fixed partial dentures

Background

Different reinforcements currently available for interim fixed partial denture (FPD) materials do not provide the ideal strength for long-term use. Therefore, the aim of this investigation was to develop a more ideal provisional material for long-term use with better mechanical properties. This study evaluated the effectiveness of polyester fiber reinforcement on different interim FPD materials.

Methods

Thirty resin-bonded FPDs were constructed from three provisional interim FPD materials. Specimens were tested with a universal testing machine (UTM). The modulus of elasticity and flexural strength were recorded in MPa. The compressive strength and degree of deflection were calculated from the obtained values, and a two-way analysis of variance (ANOVA) was used to determine the significance.

Results

The polyester fiber reinforcement increased the mechanical properties. The modulus of elasticity for heat-polymerized polymethyl methacrylate (PMMA) was 624 MPa, compared to 700.2 MPa for the reinforced heat-cured sample. The flexural strengths of the bis-acrylic and cold-polymerized reinforced samples increased significantly to 2807 MPa and 979.86 MPa, respectively, compared to the nonreinforced samples. The mean compressive strength of the reinforced cold-polymerized PMMA samples was 439.17 MPa; and for the reinforced heat-polymerized PMMA samples, it was 1117.41 MPa. The degree of deflection was significantly greater (P < 0.05) in the reinforced bis-acrylic sample (5.03 MPa), compared with the nonreinforced bis-acrylic sample (2.95 MPa).

Conclusion

Within the limitations of this study, polyester fiber reinforcements improved the mechanical properties of heat-polymerized PMMA, cold-polymerized PMMA, and bis-acrylic provisional FPD materials.     

带涤纶套半永久血透导管在血液透析中的应用分析

目的：分析和探讨带涤纶套半永久血透导管在血液透析中临床研究及应用。方法：对2011年5月-2013年5月收治的40例尿毒症患者通过建立皮下隧道及Seldinger 技术留置带涤纶套血透导管进行维持性血液透析,观察其置管使用时间及并发症等情况。结果：患者带涤纶套半永久血透导管留置时间最短者4个月,最长者超过2年且至今仍在用,平均18.5个月。与临时导管比较,血流量、尿素清除指数（KT/V）方面比较差异均无统计学意义（P〉0.05）;但带涤纶套半永久血透导管出现感染、血栓形成、脱管等并发症情况更低、使用时间更长（P〈0.05）。结论：带涤纶套半永久血透导管对于血管条件差、无法建立内瘘,尤其在条件有限基层医院的透析患者提供一条可行的长期血管通路,确保透析继续顺利进行具有重要意义。     

Vegetable-oil-based polymers as future polymeric biomaterials

Vegetable oils are one of the most important classes of bio-resources for producing polymeric materials. The main components of vegetable oils are triglycerides – esters of glycerol with three fatty acids. Several highly reactive sites including double bonds, allylic positions and the ester groups are present in triglycerides from which a great variety of polymers with different structures and functionalities can be prepared. Vegetable-oil-based polyurethane, polyester, polyether and polyolefin are the four most important classes of polymers, many of which have excellent biocompatibilities and unique properties including shape memory. In view of these characteristics, vegetable-oil-based polymers play an important role in biomaterials and have attracted increasing attention from the polymer community. Here we comprehensively review recent developments in the preparation of vegetable-oil-based polyurethane, polyester, polyether and polyolefin, all of which have potential applications as biomaterials.     

Resisting protein adsorption on biodegradable polyester brushes

The protein adsorption and degradation behaviors of poly(lactic acid), poly(glycolic acid) (PGA) and poly(ε-caprolactone) (PCL) brushes and their co-polymer brushes with oligo(ethylene glycol) (OEG) were studied. Both brush structure and relative amount of OEG and polyester were found to be important to the protein resistance of the brushes. A protein-resisting surface can be fabricated either by using OEG as the top layer of a copolymer brush or by increasing the amount of OEG relative to polyester when using a hydroxyl terminated OEG (OEG-OH) and a methoxy terminated OEG (OEG-OMe) mixture as the substrate layer. The degradation of single polyester brushes and their co-polymer brushes using OEG-OH as a substrate layer or using OEG as a top layer was hindered. This phenomenon was rationalized by the inhibition of the proposed back-biting process as the hydroxy end groups of polyester were blocked by OEG molecules. Among these brushes tested, PGA co-polymer brushes using the methoxy/hydroxyl OEG mixture as the substrate layer proved to be both protein-resistant and degradable due to the relatively large amount of OEG moieties and the good biodegradability of PGA.     

Loss of Amino Acids Into Dialysate During Hemodialysis Using Hydrophilic and Nonhydrophilic Polyester–Polymer Alloy and Polyacrylonitrile Membrane Dialyzers

During hemodialysis, amino acid loss through the dialysate remained a significant problem and was not clear in some dialyzers; therefore, we investigated amino acid loss with hydrophilic and nonhydrophilic polyester–polymer alloy membranes and polyacrylonitrile membranes. Nine maintenance hemodialysis patients were studied to assess amino acid loss during hemodialysis with the three membranes. Total amino acid losses were 85.7 ± 27.2 mg/L, 83.3 ± 16.1 mg/L, and 72.1 ± 22.5 mg/L with the hydrophilic, nonhydrophilic polyester–polymer alloy, and polyacrylonitrile membranes, respectively. Amino acid losses were greater with the hydrophilic membrane compared with the polyacrylonitrile membrane for ornithine (2.0 ± 0.6 vs. 1.4 ± 0.4 mg/L, P = 0.025), phenylalanine (2.4 ± 0.9 vs. 1.8 ± 0.8 mg/L, P = 0.012), and tryptophan (0.6 ± 0.2 vs. 0.4 ± 0.2 mg/L, P = 0.023). Amino acid losses were greater with the nonhydrophilic membrane than with the polyacrylonitrile membrane for ornithine (2.0 ± 0.4 vs. 1.4 ± 0.4 mg/L, P = 0.017), phenylalanine (2.3 ± 0.5 vs. 1.8 ± 0.8 mg/L, P = 0.018), tryptophan (0.7 ± 0.2 vs. 0.4 ± 0.2 mg/L, P = 0.003), and cystine (3.2 ± 0.7 vs. 2.0 ± 0.7 mg/L, P = 0.005). In conclusion, greater losses of ornithine, phenylalanine, tryptophan, and cystine were observed with polyester–polymer alloy than with polyacrylonitrile membranes during hemodialysis. Constant attention should be paid to the amino acid loss profile to improve nutritional control in hemodialysis patients.     

Is the Guideline the Cause of Structural Failure in Current Polyester Vascular Prostheses? An Experimental Study

To evaluate the impact of the guideline on the structural failure of current polyester vascular prostheses, we studied seven unsealed polyester vascular prostheses. An accelerated time test was used for assessing degradation of polymeric medical materials at pH 7.4 in phosphate buffer at a temperature of 95 degrees C. Probe burst strength was determined on the guideline and on standard parts of the prostheses during the accelerated time test. Weight-average molecular weights of the guideline and of the standard parts in all knitted grafts during the accelerated time test were measured. The guideline was significantly weaker than the standard parts in most prostheses. The guideline had significantly lower values of weight-average molecular weights than the standard parts in most knitted grafts. This study showed that guideline degeneration was one factor responsible for the structural failure of some current polyester vascular prostheses.