The reverse function of lignin-degrading enzymes: The polymerization ability to promote the formation of humic substances in domesticated composting.

This study aimed to confirm the ability of lignin peroxidase (LiP) and manganese peroxidase (MnP) in promoting the formation of humic substances (HS) during domesticated composting. Three raw materials with different lignin types were used for composting, including rice straw, tree branches, and pine needles. Results suggested that LiP and MnP activity increased during domesticated composting. But HS formation was only promoted by LiP. The effect of MnP was insignificant, which might be caused by the lack of enzyme cofactors like Mn2+. Meanwhile, bacteria highly associated with LiP and MnP production were identified as core bacteria. Function prediction of 16S-PICRUSt2 showed that the function of core bacteria was consistent with total bacterial functions which mainly promoted compost humification. Therefore, it speculated that LiP and MnP had the ability to promote HS formation during composting. Accordingly, it is a new understanding of the role of biological enzymes in composting.

A case report of intracardiac bone cement embolization after posterior decompression and cement-enhanced pedicle screw fixation for osteoporosis and lumbar degeneration.

RATIONALE: Bone cement leakage is a common complication of percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP) surgery and has also been reported in posterior decompression and cement-enhanced pedicle screw fixation. When bone cement leaks through the venous system, it will have serious consequences and even endanger the life of the patient, especially when the bone cement causes intracardiac embolism. PATIENT CONCERNS: A 70-year-old woman developed chest tightness and decreased blood oxygen saturation following posterior decompression and cement-enhanced pedicle screw fixation. DIAGNOSIS: After the patient was given symptomatic treatment, the symptoms were not relieved, the high-sensitivity troponin I level continued to rise, the electrocardiogram results were abnormal, and chest computed tomography (CT) revealed multiple flaky and strip-shaped dense shadows in the heart. INTERVENTION: The patient underwent removal of foreign bodies from the heart under cardiopulmonary bypass and tricuspid valvuloplasty, removal of intracardiac bone cement, and repair of the tricuspid valve and chordae. OUTCOME: The patient recovered well postoperatively and was discharged from the hospital after 3 weeks. There were no intracardiac foreign bodies observed on chest CT after the operation. LESSONS: For patients with cardiopulmonary discomfort after posterior decompression and bone cement-enhanced pedicle screw fixation, in view of the limitations of radiographic examination, we recommend performing chest CT examination to confirm the diagnosis. For patients with intravascular foreign body embolism, multidisciplinary team joint treatment saves lives.