The effects of reaction temperature, pH, substrate and enzyme concentration, deacetylation degree of chitosan on the hydrolytic velocity of chitosan by Lysozyme were investigated. The results showed that the specificity of catalyst obey the dynamics of michae-lis-Menten. The optimum temperature and pH were 50℃ and 6. 0 respectively, the reaction velocity was reduced while the deacetylation degree of chitosan was raised. The mean molecular weight of low molecular chitosan has been determined by high performance liquid chro-matography method, the mean molecular weight was 8328.

PURPOSE: Conditional survival (CS) provides important information on survival for a period of time after diagnosis. Currently, information on CS patterns of patients with nasopharyngeal carcinoma (NPC) is lacking. We aimed to analyze survival rate over time and estimate CS for NPC patients using a national population-based registry. MATERIALS AND METHODS: Patients diagnosed with NPC between 1973 and 2007 with at least 5-year follow-up were identified from the Surveillance Epidemiology End Results registry. Traditional survival rates and crude CS estimateswere calculated using Kaplan-Meier analysis. Risk-adjusted survival curves were plotted from the proportional hazards model using the correct group prognosis method. RESULTS: For 7,713 patients analyzed, adjusted baseline 5-year overall survival improved significantly from 36.0% in patients diagnosed in 1973-1979, 41.7% in 1980-1989, 46.6% in 1990-1999, to 54.7% in 2000-2007 (p < 0.01). CS analysis demonstrated that for every additional year survived, adjusted probability of surviving the next 5 years increased from 66.7% (localized), 54.0% (regional), and 35.3% (distant) at the time of diagnosis, to 83.7% (localized), 75.0% (regional), and 62.2% (distant) for patients who had survived 5 years. Adjusted 5-year CS differed among age, sex, tumor histology, ethnicity, and stage subgroups initially, but converged with time. CONCLUSION: Treatment outcomes of NPC patients have greatly improved over the decades. Increases in CS become more prominent in patients with distant disease than in those with localized or regional disease as patients survive longer. CS provides more dynamic prognostic information for patients who have survived a period of time after diagnosis.
Diagnosis ; Epidemiology* ; Follow-Up Studies ; Humans ; Kaplan-Meier Estimate ; Methods ; Nasopharyngeal Neoplasms ; Prognosis ; Proportional Hazards Models ; SEER Program ; Survival Rate

PURPOSE: Local relapse-free survival (LRFS) differs widely among patients with T4 category nasopharyngeal carcinoma (NPC). We aimed to build a nomogram incorporating clinicopathological information to predict LRFS in T4 NPC after definitive intensity-modulated radiation therapy (IMRT). MATERIALS AND METHODS: Retrospective study of 415 Chinese patients with non-metastatic T4 NPC treated with definitive IMRT with or without chemotherapy at our cancer center between October 2009 and September 2013. The nomogram for LRFS at 3 and 5 years was generated based on multivariate Cox proportional hazards regression, and validated using bootstrap resampling, assessing discriminative performance using the concordance index (C-index) and determining calibration ability via calibration curves. RESULTS: Five-year LRFS was 88.8%. We identified and incorporated four independent prognostic factors for LRFS: ethmoid sinus invasion, primary gross tumor volume, age, and pretreatment body mass index. The C-index of the nomogram for local recurrence was 0.732 (95% confidence interval, 0.726 to 0.738), indicating excellent predictive accuracy. The calibration curve revealed excellent agreement between nomogram-predicted and observed LRFS probabilities. Risk subgroups based on total point score cutoff values enabled effective discrimination of LRFS. CONCLUSION: This pretreatment nomogram enables clinicians to accurately predict LRFS in T4 NPC after definitive IMRT, and could help to facilitate personalized patient counselling and treatment strategies.
Asian Continental Ancestry Group* ; Body Mass Index ; Calibration ; Discrimination (Psychology) ; Drug Therapy ; Ethmoid Sinus ; Humans ; Nomograms* ; Recurrence* ; Retrospective Studies* ; Tumor Burden