Biodegradation of polyethylene terephthalate: a review / 生物工程学报

Plastics are widely used in human daily life, which bring great convenience. Nevertheless, the disposal of a large amount of plastic wastes also brings great pressure to the environment. Polyethylene terephthalate (PET) is a polymer thermoplastic material produced from petroleum. It has become one of the most commonly used plastics in the world due to its durability, high transparency, light weight and other characteristics. PET can exist in nature for a long time due to its complex structure and the difficulty in degradation, which causes serious pollution to the global ecological environment, and threatens human health. The degradation of PET wastes has since become one of the global challenges. Compared with physical and chemical methods, biodegradation is the greenest way for treating PET wastes. This review summarizes the recent advances on PET biodegradation including microbial and enzymatic degradation of PET, biodegradation pathway, biodegradation mechanisms, and molecular modification of PET-degrading enzymes. In addition, the prospect for achieveing efficient degradation of PET, searching and improving microorganisms or enzymes that can degrade PET of high crystallinity are presented, with the aimto facilitate the development, application and molecular modification of PET biodegradation microorganisms or enzymes.

Detection methods for polyethylene terephthalate degrading enzymes: a review / 生物工程学报

Polyethylene terephthalate (PET) is one of the most widely used synthetic polyester. It poses serious threat to terrestrial, aquatic ecosystems and human health since it is difficult to be broken down and deposited in the environment. The biodegradation based on enzymatic catalysis offers a sustainable method for recycling PET. A number of PET hydrolases have been discovered in the last 20 years, and protein engineering has increased their degradation capabilities. However, no PET hydrolases that are practical for widespread industrial use have been identified. Screening of PET hydrolase using conventional detection techniques is laborious and inefficient process. Effective detection techniques are required to promote the commercialization of PET hydrolases. Using efficient detection techniques to screen potent industrial enzymes is essential for supporting the widespread industrial implementation of PET hydrolases. To define PET hydrolase, scientists have created a number of analytical techniques recently. The detection techniques that can be used to screen PET hydrolase, including high performance liquid chromatography, ultraviolet absorption spectrometric, and fluorescence activated droplet sorting method, are summarized in this study along with their potential applications.

Engineering the plastic degradation enzyme Ple629 from marine consortium to improve its thermal stability / 生物工程学报

Petrochemical-derived polyester plastics such as polyethylene terephthalate (PET) and polybutylene adipate terephthalate (PBAT) have been widely used. However, the difficulty to be degraded in nature (PET) or the long biodegradation cycle (PBAT) resulted in serious environmental pollution. In this connection, treating these plastic wastes properly becomes one of the challenges of environment protection. From the perspective of circular economy, biologically depolymerizing the waste of polyester plastics and reusing the depolymerized products is one of the most promising directions. Recent years have seen many reports on polyester plastics degrading organisms and enzymes. Highly efficient degrading enzymes, especially those with better thermal stability, will be conducive to their application. The mesophilic plastic-degrading enzyme Ple629 from the marine microbial metagenome is capable of degrading PET and PBAT at room temperature, but it cannot tolerate high temperature, which hampers its potential application. On the basis of the three-dimensional structure of Ple629 obtained from our previous study, we identified some sites which might be important for its thermal stability by structural comparison and mutation energy analysis. We carried out transformation design, and performed expression, purification and thermal stability determination of the mutants. The melting temperature (Tm) values of mutants V80C and D226C/S281C were increased by 5.2 ℃ and 6.9 ℃, respectively, and the activity of mutant D226C/S281C was also increased by 1.5 times compared with that of the wild-type enzyme. These results provide useful information for future engineering and application of Ple629 in polyester plastic degradation.

Enzymatic properties and degradation characterization of a bis(2-hydroxyethyl) terephthalate hydrolase from Saccharothrix sp / 生物工程学报

The discovery of new enzymes for poly(ethylene terephthalate) (PET) degradation has been a hot topic of research globally. Bis-(2-hydroxyethyl) terephthalate (BHET) is an intermediate compound in the degradation of PET and competes with PET for the substrate binding site of the PET-degrading enzyme, thereby inhibiting further degradation of PET. Discovery of new BHET degradation enzymes may contribute to improving the degradation efficiency of PET. In this paper, we discovered a hydrolase gene sle (ID: CP064192.1, 5085270-5086049) from Saccharothrix luteola, which can hydrolyze BHET into mono-(2-hydroxyethyl) terephthalate (MHET) and terephthalic acid (TPA). BHET hydrolase (Sle) was heterologously expressed in Escherichia coli using a recombinant plasmid, and the highest protein expression was achieved at a final concentration of 0.4 mmol/L of isopropyl-β-d-thiogalactoside (IPTG), an induction duration of 12 h and an induction temperature of 20 ℃. The recombinant Sle was purified by nickel affinity chromatography, anion exchange chromatography, and gel filtration chromatography, and its enzymatic properties were also characterized. The optimum temperature and pH of Sle were 35 ℃ and 8.0, and more than 80% of the enzyme activity could be maintained in the range of 25-35 ℃ and pH 7.0-9.0 and Co2+ could improve the enzyme activity. Sle belongs to the dienelactone hydrolase (DLH) superfamily and possesses the typical catalytic triad of the family, and the predicted catalytic sites are S129, D175, and H207. Finally, the enzyme was identified as a BHET degrading enzyme by high performance liquid chromatography (HPLC). This study provides a new enzyme resource for the efficient enzymatic degradation of PET plastics.

Expression, purification and characterization of a novel bis (hydroxyethyl) terephthalate hydrolase from Hydrogenobacter thermophilus / 生物工程学报

PET (polyethylene terephthalate) is one of the most important petrochemicals that is widely used in mineral water bottles, food and beverage packaging and textile industry. Because of its stability under environmental conditions, the massive amount of PET wastes caused serious environmental pollution. The use of enzymes to depolymerize PET wastes and upcycling is one of the important directions for plastics pollution control, among which the key is the depolymerization efficiency of PET by PET hydrolase. BHET (bis(hydroxyethyl) terephthalate) is the main intermediate of PET hydrolysis, its accumulation can hinder the degradation efficiency of PET hydrolase significantly, and the synergistic use of PET hydrolase and BHET hydrolase can improve the PET hydrolysis efficiency. In this study, a dienolactone hydrolase from Hydrogenobacter thermophilus which can degrade BHET (HtBHETase) was identified. After heterologous expression in Escherichia coli and purification, the enzymatic properties of HtBHETase were studied. HtBHETase shows higher catalytic activity towards esters with short carbon chains such as p-nitrophenol acetate. The optimal pH and temperature of the reaction with BHET were 5.0 and 55 ℃, respectively. HtBHETase exhibited excellent thermostability, and retained over 80% residual activity after treatment at 80 ℃ for 1 hour. These results indicate that HtBHETase has potential in biological PET depolymerization, which may facilitate the enzymatic degradation of PET.

Advances in poly(ethylene terephthalate) hydrolases / 生物工程学报

Plastics have brought invaluable convenience to human life since it was firstly synthesized in the last century. However, the stable polymer structure of plastics led to the continuous accumulation of plastic wastes, which poses serious threats to the ecological environment and human health. Poly(ethylene terephthalate) (PET) is the most widely produced polyester plastics. Recent researches on PET hydrolases have shown great potential of enzymatic degradation and recycling of plastics. Meanwhile, the biodegradation pathway of PET has become a reference model for the biodegradation of other plastics. This review summarizes the sources of PET hydrolases and their degradation capacity, degradation mechanism of PET by the most representative PET hydrolase-IsPETase, and recently reported highly efficient degrading enzymes through enzyme engineering. The advances of PET hydrolases may facilitate the research on the degradation mechanism of PET and further exploration and engineering of efficient PET degradation enzymes.

Commentary: polymer binding modules accelerate enzymatic degradation of poly(ethylene terephthalate) / 生物工程学报

The large scale production and indiscriminate use of plastics led to serious environmental pollution. To reduce the negative effects of plastics waste on the environment, an approach of enzymatic degradation was put forward to catalyze plastics degradation. Protein engineering strategies have been applied to improve the plastics degrading enzyme properties such as activity and thermal stability. In addition, polymer binding modules were found to accelerate the enzymatic degradation of plastics. In this article, we introduced a recent work published in Chem Catalysis, which studied the role of binding modules in enzymatic hydrolysis of poly(ethylene terephthalate) (PET) at high-solids loadings. Graham et al. found that binding modules accelerated PET enzymatic degradation at low PET loading (< 10 wt%) and the enhanced degradation cannot be observed at high PET loading (10 wt%-20 wt%). This work is beneficial for the industrial application of polymer binding modules in plastics degradation.

Migração de partícula alergênica através de embalagem pet / Migration of allergen particles through pet

Para garantia da segurança dos consumidores muitas decisões na indústria alimentícia são tomadas com "margem de segurança", uma delas é a dispersão de partículas alergênicas em contaminações cruzadas. Em estoques de bebidas embaladas, diversas unidades que não possuem ingredientes alergênicos ou traços são descartadas quando um produto alergênico entra em contato, mesmo que pela parte externa. O presente estudo teve como objetivo avaliar se a partícula alergênica externa migra pela embalagem de PET e contamina a bebida não alergênico. Para isso, um produto em embalagem PET sem ingredientes ou partículas alergênicas (água) teve sua parte externa exposta a um ingrediente alergênico (soja) em meio aquoso e oleoso por 1, 24, 48 e 72 horas, demonstrando que não há migração para a parte interna.

To ensure the safety of consumers, many decisions in the food industry are made with "margin of safety", one is the dispersion of allergenic particles in cross-contamination. In stocks of packaged beverages, several units that do not contain allergenic ingredients or traces are discarded when an allergenic product comes into contact, even out of pack. The objective of this study is to evaluate whether the external allergenic particle migrates through the PET packaging and contaminates the non-allergenic food. A product in PET packaging without allergenic ingredients or particles (water) has your external part exposed to an allergenic ingredient (soy) in an aqueous and oily medium for 1, 24, 48 and 72 hours, and tested if are migration.

The application of carbohydrate binding module-Thermobifida fusca cutinase fusion protein in polyethylene terephthalate degradation / 生物工程学报

With the development of global economy, the dramatically increased production of polyethylene terephthalate (PET) plastics has led to a remarkably increased amount of plastic waste. PET waste can be treated by landfill, incineration, or biodegradation. While landfilling and incineration may cause secondary pollution, biodegradation has since received increased attentions due to its environmental friendliness. Recent studies have indicated that the carbohydrate binding module (CBM) can effectively enhance the binding of PET degrading enzymes to PET, and consequently increasing PET degradation rate. Here we constructed a fusion protein BaCBM2-Tfuc containing the BaCBM2 from Bacillus anthraci and the cutinase Tfuc from Thermobifida fusca, by megaprimer PCR of whole plasmids (MEGAWHOP). Notabaly, the PET film degradation efficiency (at 60 ℃) of BaCBM2-Tfuc was 2.8 times that of Tfuc. This study may provide technical support for constructing fusion proteins capable of efficiently degrading PET.

Structure-based engineering of PET hydrolase from Ideonella sakaiensis / 生物工程学报

Polyethylene terephthalate (PET) is a synthetic polymer consisting of ester bond-linked terephthalate and ethylene glycol. Tremendous amounts of PET have been produced and majority of them enters terrestrial and marine environment as wastes, posing serious threats to the global ecosystems. In 2016, a PET hydrolase from a PET-assimilating bacterium Ideonalla sakaiensis was reported and termed as IsPETase. This enzyme outperforms other PET-hydrolyzing enzymes in terms of its PET hydrolytic activity at ambient temperature, thus holds a great promise for PET biodegradation. In order to improve IsPETase activity, we conducted structure-based engineering to modify the putative substrate-binding tunnel. Among the several variants to the N233 residue of IsPETase, we discovered that the substitution of N233 with alanine increases its PET hydrolytic activity, which can be further enhanced when combined with a R280A mutation. We also determined the X-ray crystal structure of the IsPETase N233A variant, which shares nearly identical fold to the WT protein, except for an open end of subsite Ⅱ. We hypothesized that the smaller side chain of N233A variant might lead to an extended subsite Ⅱ for PET binding, which subsequently increases the enzymatic activity. Thus, this study provides new clues for further structure-based engineering of PETase.

Biodegradation of Terephthalic Acid by Isolated Active Sludge Microorganisms and Monitoring of Bacteria in a Continuous Stirred Tank Reactor

Abstract Terephthalic acid is extensively used as an important raw material in polyester fibers, as well as the production of polyethylene terephthalate bottles and textile industries. Especially, in the petrochemical industry, toxic chemicals are released to the atmosphere during the production of polyethylene terephthalate, unless the wastewater treatment is carried out. It's a well-known fact that chemicals have serious side effects on human health, so manufacturing companies should not dispose of such harmful chemicals without treatment. Biodegradation is an effective option for eco-friendly degradation of hydrocarbons. Hydrocarbon-degrading bacteria are everywhere in environment and can utilize these chemicals as sources of carbon and energy. In the present study, aerobic bacterial strains T1, T4, T5, and TK were isolated from activated sludge and crude oil deposits of a petrochemical company in Turkey. The strains were identified to be Pseudomonas sp., Chryseobacterium sp., Burkholderia sp., and Arthrobacter sp. according to morphological, physiological and biochemical characteristics. The strains were able to degrade about 100% of 100 mg/L terephthalic acid within, respectively, 8, 67, 52, 24 hour as sole carbon and energy source. Therefore, these isolates can be effectively used for degradation of terephthalic acid contaminated sites. In addition to this, a Continuous Stirred Tank Reactor (CSTR) was used to test the biodegradation capabilities of the isolates in the activated sludge system. Throughout the biodegradation, bacterial existence and numbers were monitored using designed primer-probe sets in real-time polymerase chain reaction (PCR).

Late Non-Anastomotic Rupture of a Bifurcated Dacron Aortic Graft Treated Using a Gore Excluder Limb Endoprosthesis

Dacron vascular prostheses have been widely used in vascular surgery since the mid-1970s. They have been proven to be the most durable and reliable conduits for arterial replacement in aortic and peripheral surgeries for decades. However, an extremely rare complication, namely late non-anastomotic graft rupture, due to intrinsic structural prosthetic disruption can occur, resulting in acute hemorrhage or false aneurysm formation. We report a case of this rare complication due to non-anastomotic rupture of a bifurcated knitted Dacron aortic vascular graft in a patient who had undergone an aorto-bi-iliac bypass 6 years ago. The patient was successfully treated in an emergency setting with endovascular therapy using an iliac limb of an abdominal aortic endoprosthesis.

Effect of Polyethylene Terephthalate Tongue Scraper on Oral Levels of Volatile Sulfur Compounds: a randomized clinical trial / Efeito do raspador de língua de polietilenotereftalato nos níveis orais de compostos sulfurados voláteis: um ensaio clínico randomizado

Objective: To evaluate the effect of Polyethylene Terephthalate (PET) tongue scraper on the volatile sulfur compound (VSC) levels. Material and Methods: A randomized, controlled, parallel design was used in this study. Out of the 48 volunteers from Dentistry Department of the Federal University of Sergipe, 40 subjects who met the inclusion criteria were randomly divided into 4 groups (n=10): G1 (control), rinsing of distilled water solution (WS); G2, WS and tongue coating removal (TCR) with toothbrush; G3, WS and TCR with a commercial tongue scraper; and G4, WS and TCR with PET tongue scraper. PET bottles were cut with a rectangular shape (1.0 cm wide x 20 cm long) to obtain PET tongue scraper. The VSC measurements were performed before (T0) and immediately after (T1) each therapy by portable sulfide monitor. Data (ppb) were submitted to Wilcoxon test (α=0.05). The differences between T0 and T1 were calculated and percentage values were assigned. Data (percentage) were submitted to ANOVA and Tukey test (α=0.05). Results: All 40 selected subjects completed the study. All groups reduced significantly the VSC levels after therapy (P<0.01). ANOVA indicated a significant difference among groups (P<0.001). The Tukey test showed that G1 (reduction of 21%) was similar to G2 (31%); G2 was similar to G3 (42%) and different from G4 (52%); G3 and G4 were similar. Conclusion: PET tongue scraper was similar to commercial tongue scraper and provided higher reductions of VSC levels than the toothbrush. (AU)

Objetivo: Avaliar o efeito do raspador de língua de polietilenotereftalato (PET) nos níveis de compostos sulfurados voláteis (CSVs). Material e Métodos: Um desenho paralelo, controlado e randomizado foi empregado neste estudo. Dos 48 voluntários do Departamento de Odontologia da Universidade Federal de Sergipe, 40 atenderam ao critério de inclusão e foram distribuídos aleatoriamente em 4 grupos (n=10): G1 (controle), bochecho com solução de água destilada (SA); G2, SA e remoção da saburra lingual (RSL) com escova dental; G3, SA e RSL com um raspador de língua comercial; e G4, SA e RSL com raspador de língua PET. Garrafas PET foram recortadas com uma forma retangular (1,0 cm de largura x 20 cm de comprimento) para obtenção dos raspadores de língua PET. As mensurações de CSVs foram realizadas antes (T0) e imediatamente após (T1) cada terapia usando um monitor portátil de enxofre. Os dados (ppb) foram submetidos ao teste de Wilcoxon (α=0,05). As diferenças entre T0 e T1 foram calculadas e transformadas em valores percentuais de redução. Os dados (percentuais) foram submetidos à ANOVA e ao teste de Tukey (α=0,05). Resultados: Todos os 40 indivíduos selecionados completaram o estudo. Em todos os grupos houve redução significante dos níveis de CSVs após terapia (P<0,01). ANOVA indicou uma diferença significante entre grupos (PP<0,001). O teste de Tukey mostrou que G1 (redução de 21%) foi semelhante a G2 (31%); G2 foi semelhante a G3 (42%) e diferente de G4 (52%); G3 e G4 foram semelhantes. Conclusão: O raspador de língua PET foi semelhante ao raspador de língua comercial e proporcionou maiores reduções de CSVs do que a escova dental. (AU)

Bond strength of resin cements to novel materials to intracanal posts applications / Resistência de união de cimentos resinosos a novos materiais para pinos intrarradiculares

Objective: Evaluate the bond strength of resin cements to new materials for application in intraradicular posts. Material and Methods: Five materials were evaluated: fiberglass, PET, polyethylene, polyacetal and PTFE. Two commercial resin cements (Rely X U200 and Rely X Arc) were applied on the test specimens of the materials (9x3mm) and the bonding was evaluated through the shear bond strength test, where the chisel operated with a load of 1kN and a velocity of 0.5mm/min at the cement/material interface. The data were analyzed by the Shapiro-Wilk test, followed by the two-way analysis of variance, performed with the Bonferroni post-test (α=0.05). Results: The glass fiber was statistically different from all evaluated materials (p0.05). Comparing the two cements, a statistical difference was found between Rely X U200 and Arc only for the glass fiber (p=0). Conclusion: PET, polyethylene, polyacetal and PTFE exhibited reduced bond strength compared to the glass fiber (AU)

Objetivo: Avaliar a resistência de união de cimentos resinosos a novos materiais para aplicação em pinos intrarradiculares. Material e método: Foram avaliados cinco materiais: fibra de vidro, PET, polietileno, poliacetal e PTFE. Dois cimentos resinosos comerciais (Rely X U200 e Rely X Arc) foram aplicados sobre os corpos de prova dos materias (9x3mm) e a resistência de união foi avaliada através do teste de cisalhamento, onde o cinzel atuou com carga de 1kN e velocidade de 0,5mm/min na interface cimento/material. Verificada a normalidade dos dados através do teste Shapiro-Wilk, foi realizada a análise de variância de dois fatores com pós-teste de Bonferroni (α=0,05). Resultados: a fibra de vidro foi diferente estatisticamtente de todos os materiais avaliados (p0,05). Comparando-se os dois cimentos, foi encontrada diferença estatística entre o Rely X U200 e Arc apenas para a fibra de vidro (p=0). Conclusão: PET, polietileno, poliacetal e PTFE apresentaram resistência de união reduzida comparando-se à fibra de vidro. (AU)

Outcomes of Open Repair of Mycotic Aortic Aneurysms with In Situ Replacement

BACKGROUND: Mycotic aortic aneurysms are rare and life-threatening. Unfortunately, no established guidelines exist for the treatment of patients with mycotic aortic aneurysms. The purpose of this study was to evaluate the midterm outcomes of the open repair of mycotic thoracic and thoracoabdominal aneurysms and suggest a therapeutic strategy. METHODS: From 2006 to 2016, 19 patients underwent open repair for an aortic aneurysm. All infected tissue was extensively debrided and covered with soft tissue. We recorded the clinical findings, anatomic location of the aneurysm, bacteriology results, antibiotic therapy, morbidity, and mortality for these cases. RESULTS: The median age was 62±7.2 years (range, 16 to 78 years), 13 patients (68%) were men, and the mean aneurysm size was 44.5±4.9 mm. The mean time from onset of illness to surgery was 14.5±2.4 days. Aortic continuity was restored in situ with a Dacron prosthesis (79%), homograft (16%), or Gore-Tex graft (5%). Soft-tissue coverage of the prosthesis was performed in 8 patients. The mean follow-up time was 43.2±11.7 months. The early mortality rate was 10.5%, and the 5-year survival rate was 74.9%±11.5%. CONCLUSION: This study showed acceptable early and midterm outcomes of open repair of mycotic aneurysms. We emphasize that aggressive intraoperative debridement with soft-tissue coverage results in a high rate of success in these high-risk patients.

A New Root-Strengthening Technique for Acute Aortic Dissection with a Weakened Aortic Root: The Neo-Adventitia Technique

BACKGROUND: Dissection flaps in acute type A aortic dissection typically extend into the root, most frequently into the non-coronary sinus (NCS). The weakened root can be susceptible not only to surgical trauma, but also to future dilatation because of its thinner layers. Herein, we describe a new technique that we named the “neo-adventitia” technique to strengthen the weakened aortic root. METHODS: From 2012 to 2016, 27 patients with acute type A aortic dissection underwent supracommissural graft replacement using our neo-adventitia technique. After we applied biologic glue between the dissected layers, we wrapped the entire NCS and the partial left and right coronary sinuses on the outside using a rectangular Dacron tube graft that served as neo-adventitia to reinforce the dissected weakened wall. Then, fixation with subannular stitches stabilized the annulus of the NCS. RESULTS: There were 4 cases of operative mortality, but all survivors were discharged with aortic regurgitation (AR) classified as mild or less. Follow-up echocardiograms were performed in 10 patients. Of these, 9 showed mild or less AR, and 1 had moderate AR without root dilatation. There were no significant differences in the size of the aortic annulus (p=0.57) or root (p=0.10) between before discharge and the last follow-up echocardiograms, and no reoperations on the aortic roots were required during the follow-up period. CONCLUSION: This technique is easy and efficient for reinforcing and stabilizing weakened roots. Furthermore, this technique may be an alternative for restoring and maintaining the geometry of the aortic root. An externally reinforced NCS could be expected to resist future dilatation.

Sequential Hybrid Repair of Aorta and Bilateral Common Iliac Arteries Secondary to Chronic Aortic Dissection with Extensive Aneurysmal Degeneration in a Marfan Patient

Marfan syndrome is a connective tissue disorder associated with aortic dissection, aneurysmal degeneration and rupture. These cardiovascular complications represent the main cause of mortality, therefore repair is indicated. We present a 35-year-old woman who experienced acute onset of chest pain. Her imaging revealed a chronic DeBakey type I dissection with aortic root dilation and descending thoracic aneurysmal degeneration. She underwent a Bentall procedure and endovascular exclusion of the descending thoracic aortic aneurysm. She was closely followed and 2 years later a computed tomography angiography (CTA) revealed the aneurysmal degeneration of the thoracoabominal aorta and bilateral iliac arteries. The patient underwent a composite reconstruction using multi-visceral branched and bifurcated Dacron grafts. At 5 years from her last surgery, a CTA revealed no new dissection or further aneurysmal degenerations. Aortic disease in Marfan patients is a complex clinical problem that may lead to secondary or tertiary aortic reconstructions; close follow-up is mandatory.

A Comparative Evaluation of Absorbable and Nonabsorbable Sutures for Open Repair of Achilles Tendon Rupture: A Pilot Study / 체질인류학회지

This pilot study was performed to compare the functional and clinical results including complications after surgery in the open repair of Achilles tendon rupture with regard to the type of suture material. A consecutive series of twenty patients with acute Achilles tendon rupture who underwent open repair were enrolled in this pilot study. The patients were divided equally into 2 groups according to suture type. In the nonabsorbable suture group, No. 2 braided nonabsorbable polyethylene terephthalate sutures were used, and in the absorbable suture group, braided absorbable polyglactin sutures were used. The Korean version of the Foot and Ankle Outcome Score (FAOS) and complications were assessed to evaluate functional and clinical result. Mean total Foot and Ankle Outcome Score (FAOS) was 89.8 (range, 71.1~100) in the nonabsorbable suture group and 82.7 (range, 61.9~92.5) in the absorbable suture group (p=0.22). All patients returned to their previous life activity. The absorbable suture group had fewer postoperative complications (10%) than the nonabsorbable suture group (20%), but there was no significant difference between two groups (p=0.45). This pilot study showed that use of an absorbable suture for Achilles tendon repair had functional and clinical results comparable to those of the nonabsorbable suture. However, a use of an absorbable suture was associated with a lower incidence of complications than the use of nonabsorbable suture. Therefore, these results have to be confirmed in a randomized controlled cohort trial with larger population.

Dacron graft intussusception technique for treatment of type a aortic dissections: technical notes and preliminary results

Abstract Introduction: Optimal surgical management for acute type A aortic dissection (AAAD) remains unclear. The in-hospital mortality rate is still high (15%), and the intraoperative bleeding is an independent risk factor for hospital mortality. Objective: The aim of our study was describe a new method for aortic anastomosis in the repair of AAAD and report the hospital mortality and bleeding complications. Methods: Between January 2008 and November 2014, 24 patients, 16 male, median age 62 years, underwent surgical treatment of AAAD. The surgical technique consisted of intussusception of a Dacron tube in the dissected aorta, which is anastomosed with a first line of 2-0 polyester everting mattress suture and a second line of 3-0 polypropylene running suture placed at the outermost side. Open distal anastomosis was performed with bilateral selective antegrade cerebral perfusion in 13 (54.1%) patients. Results: Cardiopulmonary bypass and aortic clamping time ranged from 75 to 135 min (mean=85 min) and 60 to 100 min (mean=67 min), respectively. The systemic circulatory arrest ranged from 29 to 60 min (mean=44.5 min). One (4.1%) patient required reoperation for bleeding, due to the use of preoperative clopidogrel. The postoperative bleeding was 382-1270 ml (mean=654 ml). We used an average of 4.2 units of red blood cells/patient. There were two (8.3%) hospital deaths, one due to intraoperative bleeding and another due to mesenteric ischemia. The average length of stay in the intensive care unit and hospital was 44 hours and 6.7 days, respectively. Conclusion: This new method for surgical correction of AAAD was reproducible and resulted in satisfactory clinical outcomes.

Non-Anastomotic Rupture of a Woven Dacron Graft in the Descending Thoracic Aorta Treated with Endovascular Stent Grafting

The intrinsic structural failure of a Dacron graft resulting from the loss of structural integrity of the graft fabric can cause late graft complications. Late non-anastomotic rupture has traditionally been treated surgically via open thoracotomy. We report a case of the successful use of thoracic endovascular repair to treat a Dacron graft rupture in the descending aorta. The rupture occurred 20 years after the graft had been placed. Two stent grafts were placed at the proximal portion of the surgical graft, covering almost its entire length.