An engineered enzyme embedded into PLA to make self-biodegradable plastic.

Plastic production reached 400 million tons in 2022 (ref. 1), with packaging and single-use plastics accounting for a substantial amount of this2. The resulting waste ends up in landfills, incineration or the environment, contributing to environmental pollution3. Shifting to biodegradable and compostable plastics is increasingly being considered as an efficient waste-management alternative4. Although polylactide (PLA) is the most widely used biosourced polymer5, its biodegradation rate under home-compost and soil conditions remains low6-8. Here we present a PLA-based plastic in which an optimized enzyme is embedded to ensure rapid biodegradation and compostability at room temperature, using a scalable industrial process. First, an 80-fold activity enhancement was achieved through structure-based rational engineering of a new hyperthermostable PLA hydrolase. Second, the enzyme was uniformly dispersed within the PLA matrix by means of a masterbatch-based melt extrusion process. The liquid enzyme formulation was incorporated in polycaprolactone, a low-melting-temperature polymer, through melt extrusion at 70 °C, forming an 'enzymated' polycaprolactone masterbatch. Masterbatch pellets were integrated into PLA by melt extrusion at 160 °C, producing an enzymated PLA film (0.02% w/w enzyme) that fully disintegrated under home-compost conditions within 20-24 weeks, meeting home-composting standards. The mechanical and degradation properties of the enzymated film were compatible with industrial packaging applications, and they remained intact during long-term storage. This innovative material not only opens new avenues for composters and biomethane production but also provides a feasible industrial solution for PLA degradation.

Comparing "intra operative" tissue engineering strategies for the repair of craniofacial bone defects.

BACKGROUND: In craniofacial reconstruction, the gold standard procedure for bone regeneration is the autologous bone graft (BG). However, this procedure requiring bone harvesting is a source of morbidity. Bone substitutes, such as biphasic calcium phosphate (BCP), represent an interesting alternative but are not sufficient for bone healing in hypoplastic conditions. In such conditions, osteoprogenitors are essential to provide osteoinduction. Previous studies have shown that BCP associated with total bone marrow (TBM) provides same bone reconstruction as bone graft in a rat model of calvaria defect. Furthermore, adipose tissue stromal vascular fraction (SVF) seems to be another promising source of osteoprogenitor cells that can be used intra-operatively. This study aimed to combine, intra-operative BCP-based bone tissue engineering strategies with TBM or SVF from human sources. METHODS: 5 mm critical-size calvaria defects were performed in 18 nude rat. The defects were filled with intra-operative bone tissue engineering procedures: human BG, human TBM + BCP, human SVF + BCP and, rat TBM + BCP. Animals were sacrificed 8 weeks after implantation and calvaria were processed for histological and radiological examinations. Implanted cells were labelled with a fluorochrome. RESULTS: Micro-CT analysis revealed partial repair of bone defect. Only hBG significantly succeeded in healing the defect (43.1%). However, low rate of newly formed bone tissue was observed in all tissue engineering conditions (hTBM, hSVF, ratTBM). DISCUSSION: The lack of bone formation observed in this study could possibly be attributed to the model. CONCLUSION: This study combined with a literature analysis show the stringency of the nude rat calvaria model in term of bone regeneration.

[Autologous serum tears: Long-term treatment in dry eye syndrome]. / Collyres de sérum autologue : traitement à long-terme dans le syndrome sec oculaire.

INTRODUCTION: Dry eye disease is a multifactorial pathology of the ocular surface. The high incidence of this pathology, as well as its significant impact on quality of life and vision and its financial cost, makes it a real public health problem. While the treatment of mild cases is generally simple and effective, treatment of severe forms is often disappointing. The use of autologous serum tears (AST) represents a therapeutic alternative for the most severe cases. The purpose of our study is to evaluate the efficacy of long-term AST treatment in patients with severe dry eye disease refractory to conventional treatment or secondary to systemic diseases such as Sjögren's syndrome or Graft versus Host disease (GVH), or ocular pathologies such as neurotrophic keratitis, chemical burns and ocular cicatricial pemphigoid. PATIENTS AND METHODS: This is a monocentric retrospective observational study conducted on 47 patients, with 83 eyes treated with autologous serum eye drops for isolated or secondary dry eye disease at the Marseille Public Hospitals between April 2014 and April 2017. The patients' subjective symptoms (ocular surface disease index [OSDI] score), their degree of satisfaction and the side effects were collected using questionnaires. Tear Break Up Time (BUT) and Schirmer scores were noted. A clinical evaluation based on fluorescein staining (Oxford score) was carried out prior to treatment with AST at P0 followed by 5 periods: P1 (between 1 and 3 months), P2 (3 to 9 months), P3 (9 to 15 months), P4 (15 months to 24 months), and P5 (>24 months). RESULTS: Out of the 83 eyes treated, the mean age was 54.39±21.56. There were 20 males (42.55 %) and 27 females (57.44 %); treatment indications consisted mainly of 25.53 % GVH, 21.27 % severe dry eye disease and 19.14 % Sjögren syndrome. The mean duration of follow-up was 9.82 months±15.50. The OSDI score decreased by 19.32 points±29.37 (P<0.05) between P0 and P1 and by 23.06 points±18.41 (P<0.05) between P0 and P4. The Oxford clinical score showed a significant decrease by the third month of treatment, between P0 and P2, by 1.32 points±1.76 (P<0.05). The Schirmer test and the BUT also showed an improvement in dry eye symptoms over time with AST, significantly at P1 (P<0.05). DISCUSSION: Complementary biological analyzes on the composition of AST are under way in order to identify predictive factors of effectiveness; patients not responding to AST treatment might respond to allogeneic serum from healthy donor cord blood. CONCLUSION: On this first series of 83 eyes treated with ASD, clinical efficacy was noted in most of the patients. No infectious complications were reported, and the satisfaction rate was very high.

Outcomes of functional treatment versus open reduction and internal fixation of condylar mandibular fracture with articular impact: A retrospective study of 83 adults.

INTRODUCTION: The treatment of fractures in the mandibular condylar process remains controversial. The aim of this study was to assess the outcomes of isolated functional treatment versus open reduction and internal fixation (ORIF) of mandibular condylar fracture with articular impact based on clinical and radiological criteria. MATERIALS AND METHODS: Eighty-three patients with a mandibular condylar fracture with articular impact were included in this retrospective study. They were divided according to Loukota, Spiessl and Schroll, Mercier and Rasse, Neff, and Hlawitschka classifications. Two groups were created: operated patients (operated) and non-operated patients (non-operated). Occlusal and functional features were evaluated using clinical measurements at 1, 3, 6, and 12 months after the treatment as well as radiological measurements performed preoperatively, 6 weeks later, and at the end of the follow-up. RESULTS: A male predominance was observed in the data (69.9%, P<0.0001). Isolated functional treatment was applied in 55 patients (66.26%). Twenty-eight patients (33.7%) were operated upon using a pre-auricular or modified Risdon's approach. Maximal mouth opening (MMO) was lesser in "operated" group compared to "non-operated" group until 6 months (25.75mm vs 31.96mm, 34.76mm vs 37.95mm, 38.06mm vs 41.87mm respectively 1, 3 and, 6 months, P<0.05). Results were satisfactory 1 year after treatment (41.29mm vs 45.22mm, P>0.05). There was no difference concerning temporo-mandibular joint dysfunctions between operated and non-operated patients. For unilateral fractures, the loss of height of the ramus was significantly higher in operated patients initially compared to "non-operated" group (P=0.0137). After surgical correction, there was no difference between the two sides of mandible. At the end of the follow-up, the there was no difference between operated and non-operated ramus (P=0.1304 and 0.6420). CONCLUSION: The present study showed that a properly followed isolated functional treatment provided similar clinical results to ORIF for mandibular condylar fractures with articular impact. Surgical treatment should be preferred when the loss of height of the ramus is severe to restore the ramus height since adult condylar remodeling is less efficient than in children.

Biochemical characterization of Arabidopsis thaliana starch branching enzyme 2.2 reveals an enzymatic positive cooperativity.

Starch Branching Enzymes (SBE) catalyze the formation of α(1 â†’ 6) branching points on starch polymers: amylopectin and amylose. SBEs are classified in two groups named type 1 and 2. Both types are present in the entire plant kingdom except in some species such as Arabidopsis thaliana that expresses two type 2 SBEs: BE2.1 and BE2.2. The present work describes in vitro enzymatic characterization of the recombinant BE2.2. The function of recombinant BE2.2 was characterized in vitro using spectrophotometry assay, native PAGE and HPAEC-PAD analysis. Size Exclusion Chromatography separation and SAXS experiments were used to identify the oligomeric state and for structural analysis of this enzyme. Optimal pH and temperature for BE2.2 activity were determined to be pH 7 and 25 °C. A glucosyl donor of at least 12 residues is required for BE2.2 activity. The reaction results in the transfer in an α(1 â†’ 6) position of a glucan preferentially composed of 6 glucosyl units. In addition, BE2.2, which has been shown to be monomeric in absence of substrate, is able to adopt different active forms in presence of branched substrates, which affect the kinetic parameters. BE2.2 has substrate specificity similar to those of the other type-2 BEs. We propose that the different conformations of the enzyme displaying more or less affinity toward its substrates would explain the adjustment of the kinetic data to the Hill equation. This work describes the enzymatic parameters of Arabidopsis BE2.2. It reveals for the first time conformational changes for a branching enzyme, leading to a positive cooperative binding process of this enzyme.

Costal graft as a support for bone regeneration after mandibular juvenile ossifying fibroma resection: An unusual case report.

Spontaneous regeneration of bone tissue after mandibular resection is rare in adults, although it does often take place in children. Periosteum conservation appears to play a major role in this healing process. We here report regarding a 5-year-old boy who exhibited a large mandibular trabecular juvenile ossifying fibroma. The lesion was treated by mandibulectomy, with careful preservation of the periosteal layer and immediate reconstruction with a costal graft by an intraoral approach. Monitoring over the course of a year revealed spontaneous mandibular regeneration, and it allowed for a series of measurements of the graft to be made. During this follow-up period, the mandibular height increased from 41.5% to 75.2% (P=0.0008) of the height of the unaffected mandibular height, while the width grew from 34.4% to 82.8% (P=0.0078) of the width of the healthy side, thus demonstrating the importance of a conservative approach regarding the periosteum in such situations. The costal graft acted as a support for bone regeneration by immobilizing the remaining bone fragments and by preventing soft-tissue prolapse.

Vertical ramus elongation and mandibular advancement by endobuccal approach: Presentation of a new osteotomy technique.

INTRODUCTION: Several surgical procedures have been proposed for the treatment of hyperdivergent dentoskeletal deformities. We propose a new osteotomy technique allowing for lengthening and advancement of the mandibular ramus by intra-oral approach. SURGICAL PROCEDURE: This technique differs from the conventional sagittal split osteotomyin that which the anterior osteotomy line is not continued until the basilar edge but stopped 5-6mm above it. Cutting of the pterygomasseteric sling is systematically done allowing for the lowering of the mandibular angle. Osteosynthesis is performed by transjugal and intra-oral approaches, using two adjustable miniplates. Our supra-angular technique allows for both elongation of the ramus and advancement of the mandible. Unlike the vertical ramus osteotomy proposed by Caldwell-Letterman, external incision and intraoperative cervical hyperextension are not required.