ABSTRACT
BACKGROUND: Oxidative stress represents tissue damage caused by reactive forms of oxygen and nitrogen due to the inability of antioxidant mechanisms to reduce reactive forms into more stable ones. The aim of the study was to evaluate the influence of surgical trauma on nitric oxide (NO) and nitrotyrosine (NT) values in patients undergoing conventional and laparoscopic cholecystectomy. METHODS: A prospective study included sixty patients from the Department of Emergency Surgery, Clinical Centre of Serbia who were operated for gallstone related chronic cholecystitis. All the patients enrolled in the study underwent cholecystectomy; the first group was operated conventionally (30 patients - control group), while the second group was operated laparoscopically (30 patients - treatment group). RESULTS: There were no statistically significant differences in the values of NO and its postoperative changes in both groups, the conventionally operated group (p=0.943) and the laparoscopically operated group (p=0.393). We found an increase in NT values 24 hours postoperatively (p=0.000) in the conventionally operated patients, while in the group operated laparoscopically we didn't find statistically significant changes in the values of NT (conventionally operated group (p=0.943) and laparoscopically operated group (p=0.393)). CONCLUSIONS: In our study, we found a significant increase in NT values 24 hours postoperatively in conventionally operated patients i.e. the control group, vs. the treatment group. Further randomized studies are needed for a better understanding of the impact of surgical trauma on oxidative stress response.
ABSTRACT
Freezing and thawing are important process steps in the manufacture of numerous biopharmaceuticals. It is well established that these process steps can significantly influence product quality attributes (PQA). Herein, we describe a physico-mathematical model to predict product temperature profiles based on the freezing program as input parameter in a commercial freeze-thaw module. Applying this model, the time from first nucleation until the last point to freeze (LPF) reaching -5°C and the time from -5°C at LPF to -30°C at LPF was varied to study the effect on PQA in a full factorial design. Effects of process parameter settings on a typical fully formulated, highly concentrated monoclonal antibody (mAb) solution as well as highly concentrated mAb solution formulated with buffer only were investigated. We found that both process phases affected PQA, such as aggregates by size-exclusion chromatography, polydispersity index by dynamic light scattering, and number of subvisible particles and turbidity in a complex way. In general, intermediate cooling and freezing times resulted in overall optimized PQA. Fully formulated mAb solution containing cryoprotectant and nonionic surfactant was significantly less affected by freezing-thawing than mAb solution formulated in buffer only.
