Enhanced recovery after surgery (ERAS) pathway for microendoscopy-assisted minimally invasive transforaminal lumbar interbody fusion.

OBJECTIVES: Enhanced recovery after surgery (ERAS) principle and minimally invasive surgery allow patients to recover faster and better postoperatively. Due to a paucity of their integration, this retrospective study aims to assess clinical outcomes of ERAS pathway in microendoscopy-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). PATIENTS AND METHODS: A total of 72 consecutive cases were enrolled. According to their inclusion order, the former 21 cases received microendoscopy-assisted MIS-TLIF without any ERAS approach (control group), while the latter 51 participants underwent the same surgery with ERAS protocol (observation group). Perioperative parameters, including operative duration, intraoperative estimated blood loss (EBL), length of stay, postoperative analgesic usage and ambulatory time, were recorded. Visual analogue scale (VAS, back and leg), Barthel index were obtained before and at three days, one month, six months postoperatively. Modified MacNab criteria and Bridwell grading were used to assess surgical outcome and interbody fusion at one week and two years after surgery, respectively. RESULTS: Observation group had statistically improved perioperative parameters (operative duration, intraoperative EBL, length of stay, postoperative analgesic usage and ambulatory time) in comparison with control group. Remarkable decreases in VAS (back and leg) were observed continuously at three days, one month and six months post-surgery in both groups when compared with scores prior to the surgery. More significant improvement of VAS (back and leg) was found in observation group at both three days and one month postoperatively. Regarding Barthel index, despite its transient decrease at three days after surgery in control group, it showed statistical increase at postoperative one month when compared with preoperative values in both groups; moreover, its inter-groups comparison revealed much more improvement in patients receiving ERAS recommendations; while at final follow-up, it continued further increase in either group. Marginally higher proportion of patients in observation group showed perfect or good clinical outcome, as well as solid interbody fusion. CONCLUSIONS: ERAS pathway in microendoscopy-assisted MIS-TLIF has advantages of decreased operative time, reduced intraoperative haemorrhage, increased initial back pain relief, decreased length of stay, lowered analgesic usage and earlier daily activity recovery and thus, benefit postoperative rehabilitation further.

Morphological regulation of Aspergillus niger to improve citric acid production by chsC gene silencing.

The mycelial morphology of Aspergillus niger, a major filamentous fungus used for citric acid production, is important for citric acid synthesis during submerged fermentation. To investigate the involvement of the chitin synthase gene, chsC, in morphogenesis and citric acid production in A. niger, an RNAi system was constructed to silence chsC and the morphological mutants were screened after transformation. The compactness of the mycelial pellets was obviously reduced in the morphological mutants, with lower proportion of dispersed mycelia. These morphological changes have caused a decrease in viscosity and subsequent improvement in oxygen and mass transfer efficiency, which may be conducive for citric acid accumulation. All the transformants exhibited improvements in citric acid production; in particular, chsC-3 showed 42.6% higher production than the original strain in the shake flask. Moreover, the high-yield strain chsC-3 exhibited excellent citric acid production potential in the scale-up process.The citric acid yield and the conversion rate of glucose of chsC-3 were both improved by 3.6%, when compared with that of the original strain in the stirred tank bioreactor.

[Synthesis of vitamin K2 by isopentenyl transferase NovA in Pichia pastoris Gpn12].

The effect of methanol addition on the heterologous expression of isoprenyl transferase NovQ was studied in Pichia pastoris Gpn12, with menadione and isopentenol as precursors to catalyze vitamin K2 (MK-3) synthesis. The expression of NovQ increased by 36% when 2% methanol was added every 24 h. The influence of initial pH, temperature, methanol addition, precursors (menadione, isopentenol) addition, catalytic time and cetyltrimethyl-ammonium bromide (CTAB) addition were explored in the P. pastoris whole-cell catalytic synthesis process of MK-3 in shaking flask. Three significant factors were then studied by response surface method. The optimal catalytic conditions obtained were as follows: catalytic temperature 31.56 ℃, menadione 295.54 mg/L, catalytic time 15.87 h. Consistent with the response surface prediction results, the optimized yield of MK-3 reached 98.47 mg/L in shaking flask, 35% higher than that of the control group. On this basis, the production in a 30-L fermenter reached 189.67 mg/L when the cell catalyst of 220 g/L (dry weight) was used to catalyze the synthesis for 24 h. This method laid the foundation for the large-scale production of MK-3 by P. pastoris Gpn12.

Biotransformation of menadione to its prenylated derivative MK-3 using recombinant Pichia pastoris.

Prenylated quinones, especially menaquinones, have significant physiological activities, but are arduous to synthesize efficiently. Due to the relaxed aromatic substrate specificity and prenylation regiospecificity at the ortho- site of the phenolic hydroxyl group, the aromatic prenyltransferase NovQ from Streptomyces may be useful in menaquinone synthesis from menadione. In this study, NovQ was overexpressed in Pichia pastoris. After fermentation optimization, NovQ production increased by 1617%. Then the different effects of metal ions, detergents and pH on the activity of purified NovQ were investigated to optimize the prenylation reaction. Finally, purified NovQ and cells containing NovQ were used for menadione prenylation in vitro and in vivo, respectively. Menaquinone-1 (MK-1) was detected as the only product in vitro with γ,γ-dimethylallyl pyrophosphate and menadione hydroquinol substrates. MK-3 at a concentration of 90.53 mg/L was detected as the major product of whole cell catalysis with 3-methyl-2-buten-1-ol and menadione hydroquinol substrates. This study realized whole cell catalysis converting menadione to menaquinones.