Design and construction of chemical-biological module clusters for degradation and assimilation of poly(ethylene terephthalate) waste.

The rising accumulation of poly(ethylene terephthalate) (PET) waste presents an urgent ecological challenge, necessitating an efficient and economical treatment technology. Here, we developed chemical-biological module clusters that perform chemical pretreatment, enzymatic degradation, and microbial assimilation for the large-scale treatment of PET waste. This module cluster included (i) a chemical pretreatment that involves incorporating polycaprolactone (PCL) at a weight ratio of 2% (PET:PCL = 98:2) into PET via mechanical blending, which effectively reduces the crystallinity and enhances degradation; (ii) enzymatic degradation using Thermobifida fusca cutinase variant (4Mz), that achieves complete degradation of pretreated PET at 300 g/L PET, with an enzymatic loading of 1 mg protein per gram of PET; and (iii) microbial assimilation, where Rhodococcus jostii RHA1 metabolizes the degradation products, assimilating each monomer at a rate above 90%. A comparative life cycle assessment demonstrated that the carbon emissions from our module clusters (0.25 kg CO2-eq/kg PET) are lower than those from other established approaches. This study pioneers a closed-loop system that seamlessly incorporates pretreatment, degradation, and assimilation processes, thus mitigating the environmental impacts of PET waste and propelling the development of a circular PET economy.

Directional-path modification strategy enhances PET hydrolase catalysis of plastic degradation.

Poly (ethylene terephthalate) (PET) is a widely used type of general plastic that produces a significant amount of waste due to its non-degradable properties. We propose a novel directional-path modification (DPM) strategy, involving positive charge amino acid introduction and binding groove remodeling, and apply it to Thermobifida fusca cutinase to enhance PET degradation. The highest value of PET degradation (90%) was achieved in variant 4Mz (H184S/Q92G/F209I/I213K), exhibiting values almost 30-fold that of the wild-type. We employed molecular docking, molecular dynamics simulations, and QM/MM MD for the degradation process of PET, accompanied by acylation and deacylation. We found that the distance of nucleophilic attack was reduced from about 4.6 Å in the wild type to 3.8 Å in 4Mz, and the free energy barrier of 4Mz dropped from 14.3 kcal/mol to 7.1 kcal/mol at the acylation which was the rate-limiting step. Subsequently, the high efficiency and universality of the DPM strategy were successfully demonstrated in LCC, Est119, and BhrPETase enhancing the degradation activity of PET. Finally, the highest degradation rate of the pretreated commercial plastic bottles had reached to 73%. The present study provides insight into the molecular binding mechanism of PET into the PET hydrolases structure and proposes a novel DPM strategy that will be useful for the engineering of more efficient enzymes for PET degradation.

Enhancement of the degradation capacity of IsPETase for PET plastic degradation by protein engineering.

The enormous waste of polyethylene terephthalate (PET) plastic has a great negative impact on the ecological environment because of its chemical inertia. To reduce the environmental threat posed by PET plastic, researchers gradually concentrate on the biodegradation of PET plastic. In this study, DuraPETaseN233C/S282C/H214S/S245R (DuraPETase-4M) was designed through protein engineering, which can be used to improve the efficiency of PET plastic biodegradation. Based on the DuraPETase, a pair of disulfide bonds (N233C/S282C) was added to improve the thermal stability. Meanwhile, the key region flexibility adjustment (H214S) was proposed to enhance the biodegradation capacity of PET plastic. Additionally, protein surface electrostatic charge optimization (S245R) was adopted to improve the binding ability between enzyme and PET plastic. Based on molecular dynamic simulations (MDs), the rationality of the design was further verified. This study provides a strategy for obtaining high-efficiency PET degradation mutants and a new possibility of environmentally friendly plastic degradation.

[Intractable facial paralysis treated with different acupuncture and acupoint embedding therapies: a randomized controlled trial].

OBJECTIVE: To compare the clinical therapeutic effects on intractable facial paralysis among acupuncture, acupoint catgut embedding and PDS embedding. METHODS: Two hundred and seventy-nine patients of intractable facial paralysis were randomized into an acupuncture group, a catgut embedding group and a PDS embedding group, 93 cases in each one. Cuanzhu (BL 2), Yuyao (EX-HN 4), Taiyang (EX-HN 5), Xuanlu (GB 5), Dicang (ST 4), Jiache (ST 6), Quanliao (SI 18), Qianzheng (Extra), Xiaguan (ST 7) and Fengchi (GB 20) on the affected side and bilateral Hegu (LI 4) and Zusanli (ST 36) were selected in the three groups. In the acupuncture group, acupuncture was applied to those acupoints, once every two days; 10 treatments made one session; the successive three sessions were required. In the catgut embedding group and the PDS embedding group, catgut and PDS were embedded separately, once every 10 days; 3 treatments made one session and the successive two sessions were required. The therapeutic cycle was 2 months in the three groups. The therapeutic results were analyzed statistically 2 months later. The scores of Sunnybrook facial nerve grading system and the facial nerve electroneurography (ENoG) were used for the efficacy assessment before and after treatment in the three groups. RESULTS: After treatment, the score of Sunnybrook facial nerve grading system was improved apparently after treatment as compared with that before treatment in any of the three groups (all P < 0.05). The score in either of the embedding groups was better than that in the acupuncture group (both P < 0.05). The difference was not significant between the catgut embedding group and the PDS embedding group (P > 0.05). After treatment, ENoG wave ampli tude values in the frontal muscle and orbicularisoris muscle on the affected side were improved as compared with those before treatment in the three groups (all P < 0.05). Those in the catgut embedding group and the PDS embedding group were better than those in the acupuncture group (all P < 0.05), and had no significant difference as compared with those on the healthy side (P > 0.05). In the acupuncture group, ENoG wave amplitudes on the affected side were lower than those on the healthy side (both P < 0.05). CONCLUSION: Acupuncture, catgut embedding and PDS embedding at acupoints all achieve the therapeutic effects on intractable facial paralysis. However, the acupoint embedding therapy presents more advantages on the recovery of facial nerve function. The efficacy is similar between the catgut embedding and the PDS embedding.

Acupuncture-associated pneumothorax.

OBJECTIVES: This article reports on a case and reviews some articles on acupuncture- induced pneumothorax published in Chinese and English medical journals since 1980. CASE: A 35-year-old man presented with left chest pain and dyspnea after receiving acupuncture. The patient was later diagnosed with a 12% pneumothorax of the left lung. He was observed in an emergency room for 24 hours while being treated with oxygen, a painkiller, antibiotics, and bedrest. A follow-up computed tomography scan of his chest 1 week later showed complete resolution of the pneumothorax. CASE ANALYSIS AND DISCUSSION: Details of the case are analyzed. A general review of the incidence, causes, symptoms, and outcomes of acupuncture induced pneumothorax is presented. In addition, improved needling methods including needling depth and angle, together with corresponding precautions are also discussed. CONCLUSIONS: Pneumothorax caused by acupuncture therapy uncommon, but the consequences can be serious. It is important for practitioners to have adequate knowledge so they can implement better prevention of acupuncture-induced pneumothorax.

[Facial nerve function index evaluation on deviation of the mouth in intractable facial palsy treated with sticking needle and traction method on three points of the mouth].

OBJECTIVE: To probe into the effective acupuncture technique for deviation of the mouth in intractable facial palsy. METHODS: One hundred and one cases of intractable facial palsy were randomly divided into an observation group (48 cases) and a control group (53 cases). Cuanzhu (BL 2), Sibai (ST 2), Jiache (ST 6) and Qianzheng (Extra) on the affected side were punctured in two groups. Additionally, three acupoints of the mouth were supplemented, named Dicang (ST 4), Kouheliao (LI 19) and Jiachengjiang (Extra) were added, and the sticking needle and traction method was adopted on them in observation group. the routine needling technique was applied in control group. The treatment was given once a day and 10-day treatment made one session. The changes in facial nerve function index (FNFI) were observed in 2 sessions of treatment. RESULTS: After treatment, FNFI in two groups increased significantly (both P < 0.01), but the improvement in observation group was better than that in control group (P < 0.01). In observation group, the basic recovery rate of FNFI was 87.5% (42/48), which was higher than that (67.9%, 36/53) in control group (P < 0.05). CONCLUSION: The sticking needle and traction method o three points is the quite effective approach in the treatment of deviation of the mouth in intractable facial palsy.