Carboxylated chitosan improved the stability of phycocyanin under acidified conditions.

Phycocyanin, a natural blue colorant, derived from Spirulina platensis, is now widely used in the food industry. However, its main drawbacks are loss of color and denature of structure in an acidic environment. In this study, carboxylated chitosan (0.1 %-1 % w/v) was chosen as an additive in acid-denatured phycocyanin for preserving phycocyanin's blue color and natural structure. Zeta-potential and particle size revealed that the carboxylated chitosan with high negative charge adsorbed on phycocyanin and provided stronger electrostatic repulsion to overcome the protein aggregation. Ultraviolet-visible absorption spectrum and fluorescence spectroscopy showed that the carboxylated chitosan recovered the microenvironment of tetrapyrrole chromophores and ß-subunits, which led the secondary structure changed and the trimers depolymerized into the monomers changed by the acidic environment. Furthermore, Fourier transform infrared spectroscopy revealed highly negatively charged carboxylated chitosan with the groups (NH2, COOH and OH) could restored the microenvironment of tetrapyrrole chromophores and ß-subunits of phycocyanin, and interact with phycocyanin through hydrogen bonding, NH bonding, ionic bonding and van der Waals, which led to a change in secondary structure and depolymerization of trimers into monomers. Our study demonstrated the carboxylated chitosan played a beneficial role in recovering the structure of acid-denatured phycocyanin and its blue color.

Portal vein-superior mesenteric vein resection and reconstruction during pancreaticoduodenectomy using the perivenous occlusion management strategy / 中华肝胆外科杂志

Objective:To explore the perivenous blocking management strategy for portal vein-superior mesenteric vein (PSMV) resection and reconstruction and its effect on postoperative complications in patients undergoing pancreaticoduodenectomy (PD).Methods:The data of 137 patients with pancreatic cancer treated with PD in Beijing Chaoyang Hospital Affiliated to Capital Medical University, Chaoyang Central Hospital, the Second Hospital of Chaoyang, Rizhao Central Hospital, the Second People's Hospital of Binzhou from January 2010 to December 2020 were collected. There were 83 males and 54 females with an average age of 61.8 years. There were 42 patients in the reconstruction group and 95 patients in the control group. The main intraoperative indexes and postoperative complications were compared between the two groups with the aim to review our experience in PSMV resection and reconstruction by using the perivenous blocking management strategy.Results:PD was successfully completed in 137 patients in the reconstruction group, the PSMV blocking time was 15-120 min, with a median of 30 min. The operation time 380 (330, 465) min, intraoperative blood loss 725 (500, 1000) ml, and postoperative hospital stay 21.0 (16.0, 28.0) d in the reconstruction group were significantly higher than those of control group [305 (280, 340) min, 400 (300, 500) ml and 18.0 (14.0, 24.5) d] (all P<0.05). The reoperation rate and perioperative mortality were 4.8% (2/42) and 2.4% (1/42) in the reconstruction group, while 2.1% (2/95) and 1.0% (1/95) in the control group, respectively. There was no significant difference between the two groups (both P>0.05). The incidence of pancreatic fistula, peritoneal effusion and infection, pulmonary infection of the reconstruction group was significantly higher than those of the control group ( P<0.05). There was no significant difference in the incidence of postoperative bleeding, delayed gastric emptying, biliary fistula, incision infection, reoperation between the two groups ( P>0.05). Conclusions:PSMV resection and reconstruction significantly increased the incidences of complication after PD, including pancreatic fistula, peritoneal effusion/infection and pulmonary infection. The perivenous blocking management strategy significantly promoted smooth postoperative recovery and effectively reduced morbidity rates of postoperative bleeding and mortality after PSMV resection and reconstruction in PD.