[Liver cancer treatment with mitochondrial homeostasis].

Systemic treatment, including molecular targeted therapy, immunotherapy, and chemotherapy, is an important means of achieving long-term survival in patients with intermediate-and advanced-stage liver cancer. However, some patients are insensitive to treatment and even develop drug resistance. Mitochondria are the center of cellular energy metabolism and, at the same time, are the priority targets for systemic therapy. Mitochondrial homeostasis plays an important role in the treatment of liver cancer. The relationship between the two advances is elucidated so as to provide better ideas for the clinical treatment of liver cancer.

MRI features and whole-lesion apparent diffusion coefficient histogram analysis of brain metastasis from non-small cell lung cancer for differentiating epidermal growth factor receptor mutation status.

AIM: To explore the utility of magnetic resonance imaging (MRI) characteristics and whole-lesion apparent diffusion coefficient histogram analysis of brain metastasis from non-small cell lung cancer (NSCLC) in the differentiation of epidermal growth factor receptor (EGFR) mutation status. MATERIALS AND METHODS: Forty-eight patients with brain metastases from NSCLC were enrolled in this retrospective study. Patients were subtyped into EGFR mutation (23 cases) and wild-type (25 cases) groups. Whole-lesion histogram metrics were derived from the apparent diffusion coefficient (ADC) maps, and imaging features were evaluated according to conventional MRI. Student's t-test or Mann-Whitney U-test, chi-squared test, and receiver operating characteristic (ROC) curve analysis were performed to discriminate the two groups and to determine the diagnostic efficacy of ADC histogram parameters. RESULTS: EGFR mutation group had more multiple brain metastases, less peritumoural brain oedema (PTBO), and lower peritumoural brain oedema index (PTBO-I) than EGFR wild-type group (all p<0.05). In addition, 90th and 75th percentiles of ADC and maximum ADC in the EGFR mutation group were significantly higher than in the EGFR wild-type group (all p<0.05). Ninetieth percentile of ADC had the highest area under the curve (AUC; 0.711), and it was found to outperform 75th percentile of ADC (AUC, 0.662; p=0.039) and maximum ADC (AUC, 0.681). CONCLUSIONS: Whole-lesion ADC histogram analysis and MRI features of brain metastasis from NSCLC are expected to be potential biomarkers to non-invasively differentiate the EGFR mutation status.

[Research progress on the mechanism and response strategies of molecular targeted drug resistance in liver cancer].

Molecular targeted drugs are one of the treatments for hepatocellular carcinoma (HCC), the primary factor influencing their therapeutic efficacy is drug resistance. Diminished drug intake, greater efflux, improved DNA damage repair capacity, aberrant signal pathways, hypoxia, epithelial-mesenchymal cell transition, and the cellular autophagy system are summarized herein as aspects of the drug resistance mechanism. Simultaneously, effective strategies for addressing drug resistance are elaborated, providing ideas for better clinical treatment of HCC.

Use of the supraclavicular artery island flap for reconstruction of maxillofacial defects: a case report and literature review.

BACKGROUND: Free flaps are widely used in maxillofacial reconstruction; however, this approach was not feasible in the current case. It was not possible because the free flap method requires microvascular anastomosis expertise, which is difficult, time-consuming and costly. CASE PRESENTATION: An 86-year-old woman suffered squamous cell carcinoma on the right side of her face, which resulted in a large soft-tissue defect. Here, we present a case of facial reconstruction from the inferior margin of the jaw to the top of the head. The size of the defect was 18.5 cm × 7.5 cm, which is rare for a patient of this age in the maxillofacial area. We used the supraclavicular artery island flap (SCAIFP) which measured 19.3 cm × 8.3 cm to repair the defect. After the operation, the flap survived without complications. Then, the patient was followed for 10 months and was satisfied with the aesthetic and functional results at the donor and recipient sites following the tumour resection. The tumour did not recur, and facial nerve function was preserved. CONCLUSION: Our results provide a new choice for the reconstruction of large defects of the head and face, and expand the potential applications of the SCAIFP.

[Risk factors and clinical prognosis analysis of carbapenem-resistant Enterobacterales bacteria nosocomial infection].

Objective: To explore the risk factors for carbapenem-resistant Enterobacterales (CRE) infection and death. Methods: A case-control analysis of 482 inpatients in 18 secondary or tertiary hospitals in Beijing in 2018 was conducted. Patients infected by CRE were selected as the case group (n=247), and infected by carbapenem susceptible Enterobacterales (CSE) as the control group (n=235). The risk factors and clinical prognosis of CRE infection were analyzed by single factor analysis and multivariate logistic regression analysis. Results: CRE were resistant to most antimicrobials, but were highly sensitive to colistin and tigecycline, with sensitivity of 94.0% and 99.5%, respectively. Multivariate analysis showed that prior 30-day tracheal intubation (OR=2.607, 95%CI: 1.655-4.108, P<0.001), empirical treatment using third or fourth generation cephalosporins (OR=2.339, 95%CI: 1.438-3.803, P=0.001), carbapenems (OR=2.468, 95%CI: 1.610-3.782, P<0.001) and quinolones (OR=2.042, 95%CI: 1.268-3.289, P=0.003) were independent risk factors for CRE infection. Mechanical ventilation (OR=3.390, 95%CI: 1.454-7.904, P=0.005), heart failure (OR=4.679, 95%CI: 1.975-11.083, P<0.001), moderate or severe liver disease (OR=3.057, 95%CI: 1.061-8.806, P=0.038), prior 30-day quinolones exposure (OR=2.882, 95%CI: 1.241-6.691, P=0.014) and septic shock (OR=7.772, 95%CI: 3.505-17.233, P<0.001) were independent risk factors for death after CRE infection. Conclusions: Reducing the use of antimicrobials and invasive procedures such as prior 30-day tracheal intubation may reduce the probability of CRE infection. Grading the severity of the underlying disease in patients with CRE infection, as well as predicting and preventing the occurrence of septic shock will help reduce the risk of death.

[Association of thallium exposure during pregnancy with maternal blood pressure and hypertensive disorder complicating pregnancy].

Objective: To investigate the association of thallium exposure during pregnancy with pregnant blood pressure changing and hypertensive disorder complicating pregnancy(HDCP). Methods: A total of 3 240 pregnant women who had establish maternal health care manual in Ma'anshan Maternal and Child Health-Care Hospital and met the inclusion and exclusion criteria were included in this study between May 2013 and September 2014.We collected their general demographic characteristics and blood pressure through questionnaire and medical records. Meanwhile we measured serum thallium concentrations by experimental technology. We use multiple logistic regression to analyze the association between thallium exposure during pregnancy and HDCP. Mixed linear model were used to analyze the association between thallium concentration and maternal systolic blood pressure (SBP) or diastolic blood pressure(DBP) in different trimesters Results: The age of 3 240 pregnant woman was (26.61±3.64) years, and the detection rate of HDCP was 5.9%(191).The median (P25, P75) of thallium concentrations in first trimester, second trimester and third trimester were 62.96 (50.79, 77.04), 62.19 (50.87, 75.26), 48.84 (38.00, 66.00) ng/L, respectively. Multiple logistic regression results suggested after adjusting various confounding factors, the risk of HDCP in pregnant women with high concentrations of thallium (>77.04 ng/L) in the first trimester is 1.75 (95%CI:1.01-3.03) times higher than which with low concentrations(<50.82 ng/L). Mixed linear model results suggested there are positive correlation between thallium concentrations with maternal DBP in first trimester (ß=1.12, 95%CI: 0.39-1.85). Conclusion: Exposure to high levels of thallium during first trimester may increase the risk of HDCP, and the exposure of thallium may be effective to DBP of pregnant.

Forensic Application of Plant Evidence.

ABSTRACT: With the increasingly obvious role of plant evidence in case detection, forensic botany, which provides clues and evidence in crime scene investigation by using botanical research method has attracted growing attention. The common experimental techniques used in forensic botany are morphological examination, physical and chemical examination, molecular genetic examination, and so on. This paper briefly expounds the advantages and disadvantages of different test methods, summarizes the problems that need to be paid attention to in the application of forensic botany by arranging the related literatures and cases of forensic botanical research, in order to provide reference for scene investigation of cases.

[Analysis of EGFR mutation and clinical features of lung cancer in Yunnan].

Objective: To analyze the EGFR mutation profile of lung cancer patients in Yunnan, and to provide evidence for clinical personalized treatment. Methods: Demographic and clinical data of 2 967 lung cancer patients undergoing EGFR identification were collected and analyzed from January 2014 to August 2019 in Yunnan Cancer Hospital. Results: The proportion of EGFR mutation in 2 967 patients with lung cancer was 46.2%. Univariate analysis showed that the proportion of EGFR mutation in women was higher than that in men (P<0.001) and displayed a downward trend with age (P=0.03). The mutation rate of ethnic minorities was higher than Han (P=0.012). Mutation rate in patients without smoking history was higher than those with smoking history (P<0.001), and patients without drinking history was higher than patients with drinking history (P<0.001). Mutation rate in patients without family history of lung cancer was higher than those with family history (P=0.008). The mutation rate of adenocarcinoma was higher than other pathological types (P<0.001). The mutation rate was different among stages, and it was higher in early patients than that in advanced patients (P<0.001). The mutation rate of tissue specimens was higher than those of cytology and peripheral blood samples (P<0.001). The mutation rate of Xuanwei area was lower than that in non-Xuanwei area (P<0.001). Multivariate analysis showed that gender (P<0.001), age (P=0.036), smoking history (P<0.001), pathological type (P<0.001), specimen type (P<0.001), and whether or not Xuanwei area (P<0.001) were the independent factors of EGFR mutation.The EGFR mutation was more common in female, non-smokers, adenocarcinoma, non-Xuanwei area, tissue specimen and young lung cancer patients.The mutation types of EGFR in 1 370 cases mainly included 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area was L858R, while in non-Xuanwei area was 19-Del.The mutation rates of G719X, G719X+ L861Q, G719X+ S768I, and S768I in Xuanwei were higher while the mutation rates of 19-Del, L858R, and 20-ins were lower than non-Xuanwei area (P<0.05). The 19-Del mutation rate of ethnic minorities is higher than that of Han (P<0.001). The combined mutation rate of G719X, L861Q in Han was higher than that of ethnic minorities (P=0.005). Conclusions: The EGFR mutation rate in lung cancer patients in Yunnan is similar to Asian and Chinese, and higher in female, non-smokers, adenocarcinomas, young and non-Xuanwei area patients. The most common types of EGFR mutation in Yunnan are 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area is L858R, while in non-Xuanwei area is 19-Del. The mutation rates of G719X, G719X+ L861Q, G719X+ S768I and S768I are higher in Xuanwei patients than those in non-Xuanwei patients. The combined mutation rate of G719X and L861Q in Han nationality is higher than that of ethnic minorities.

[Driver genes expression and clinical characteristics of targeted therapy in non-small cell lung cancer in Yunnan-Kweichow Plateau].

Objective: To analyze the expressions of non-small-cell lung cancer (NSCLC) driver genes and their mutation distribution characteristics in the Yunnan-Kweichow plateau, and to provide evidences for personalized molecular targeted therapy of lung cancer in high-incidence areas. Methods: A retrospective analysis was performed on the medical records of patients with NSCLC who underwent combined lung cancer 8 gene detection, including epidermal growth factor receptor (EGFR), rat sarcoma viral oncogene (RAS), anaplastic lymphoma kinase (ALK), RET proto-oncogene (RET), v-Raf murine sarcoma viral oncogene homolog (BRAF), ROS proto-oncogene 1 (ROS1), human epidermal growth factor receptor-2 (HER-2), and cellular-mesenchymal to epithelial transition factor (MET), from January 2016 to August 2019 in Yunnan Cancer Hospital. Besides, we analyzed the expressions of NSCLC driver genes and their mutation distributions. Results: The positive rate of NSCLC driver genes in Yunnan was 67.05%(1 508/2 249). The mutation rates in Xishuangbanna (76.92%), Yuxi (72.38%), Xuanwei (71.88%), Qujing (71.24%), and Honghe (71.79%) were significantly higher than other areas. The mutation rates of Hui (84.38%), Hani (85.00%), Zhuang (75.00%), Buyi (100%), Manchu (100%), Tujia (100%) and Achang (100%) are significantly higher than the minority national average. Driver gene mutations were related to gender (P<0.001), smoking history (P<0.001), age (P<0.001), pathological type (P<0.001), and whether the Xuanwei area (P=0.027), but not related to the nationality (P=0.748) and family history of lung cancer (P=0.676). The mutation rates of EGFR, RAS, BRAF, HER-2 and MET genes were 44.46%, 10.98%, 1.24%, 0.89% and 0.76%, and the rearrangement rates of ALK, RET and ROS1 genes were 4.67%, 1.29% and 0.89%, respectively.The mutation rate of EGFR in females was 56.67%, which was higher than 33.19% in males (P<0.001). The mutation rate of RAS in males was 12.66%, which was higher than 9.17% in females (P=0.010). The mutation rate of RAS in the Han was 11.49%, which was higher than 7.17% in the minority (P=0.032). The rate of RAS mutation in Xuanwei patients was 24.74%, significantly higher than 8.15% in non-Xuanwei area (P<0.001), and the EGFR mutation rate was 40.63%, which was lower than 45.25% in non-Xuanwei area (P=0.045). The rate of ALK rearrangement in Xuanwei patients was 1.56%, which was significantly lower than 5.31% in the non-Xuanwei area (P<0.001), and no HER-2 mutation patients were detected in Xuanwei area. The mutation rate of EGFR in patients with non-smoking history was 51.10%, significantly higher than 29.70% of patients with smoking history (P<0.001). Meanwhile, the rate of ALK rearrangement with non-smoking history patients was 5.35%, which was also higher than 3.16% of patients with smoking history (P<0.001). The rate of RAS mutation in patients with non-smoking history was 9.34%, lower than 14.63% of patients with smoking history (P=0.008). Conclusions: The positive rate of driven gene expression in NSCLC patients from the Yunnan-Kweichow Plateau is slightly lower than the national average. The rates of EGFR and RAS mutations are similar to the domestic average. The rates of ROS1, ALK and RET genes rearrangements and the rates of BRAF, HER2 and MET gene mutations are slightly lower than the national average. EGFR, RAS and ALK genes in the NSCLC patients from Yunnan-Kweichow Plateau have high positive rates, and display different demographic and clinical characteristics, which are of great significance in the selection of targeted therapy populations.

[Adverse maternal and infant health effects caused by thallium exposure during pregnancy].

Thallium is a highly toxic heavy metal. The adverse maternal and infant health effects caused by thallium exposure during pregnancy have also attracted more and more scholars' attention. This study focused on the sources of thallium exposure and its influencing factors, the association between thallium exposure during pregnancy and pregnancy complications and adverse birth outcomes in newborns, the effects of thallium exposure during pregnancy on children's growth and development after birth. In terms of potential mechanisms, the related research progress was reviewed in this study, which could provide a new basis for further research on the harm, prevention and control of thallium exposure during pregnancy.

[Analysis on epidemic situation and spatiotemporal changes of COVID-19 in Anhui].

We used the epidemic data of COVID-19 published on the official website of the municipal health commissions in Anhui province to map the spatiotemporal changes of confirmed cases, fit the epidemic situation by the population growth curve at different stages and analyze the epidemic situation in Anhui Province. It was found that the cumulative incidence of COVID-19 was 156/100 000 by February 18, 2020 and the trend of COVID-19 epidemic declined after February 7 with a change from J-shaped curve to S-shaped curve. As the reporting time of cases might be 3-5 days later than the actual onset time, the number of new cases in Anhui province actually began to decline around February 2 to February 4, 2020.

Identification of Magnolia wufengensis (Magnoliaceae) cultivars using phenotypic traits, SSR and SRAP markers: insights into breeding and conservation.

A combination of phenotypic characterization and molecular markers may provide reliable information on new plant varieties and elucidate the conservation status of rare species. Five newly developed Magnolia wufengensis cultivars, an endangered plant species endemic to Hubei Province, China, possess more distinctive phenotypes than common Magnolia cultivars. With reference to a wild species population of M. wufengensis and a population of Magnolia denudata, morphological traits of flower organs, simple sequence repeat (SSR), and sequence-related amplified polymorphism (SRAP) markers were used. In the morphological study, six traits of floral organs were investigated and their relationships were analyzed between cultivars. In the genetic study, 9 SSR primer pairs and 10 SRAP primer combinations were screened. The five cultivars maintained a high level of genetic diversity. Genetic diversity of each M. wufengensis cultivar was much lower than that of the wild population, but was slightly higher than that of the M. denudata population. Analysis of molecular variance (AMOVA) revealed that genetic variation among populations was 20% (SRAP) and 30% (SSR), which showed a high degree of genetic differentiation among populations of the five cultivars. The dendrograms illustrated a clear separation between M. wufengensis populations and outer species, and identified two major groups among cultivars. Correlation analysis indicated a good fit between the two marker systems, but a relatively low fit between morphological and genetic traits (SRAP: r = 0.60, SSR: r = 0.52). These findings provide reliable references for the application of these molecular markers in the breeding and conservation of M. wufengensis.

[Influence of tibial component slope on short-term clinical outcome for Oxford unicompartmental knee arthroplasty].

Objective: To investigate the effects of tibial component slope change after microplasty (MP) Oxford unicompartmental knee arthroplasty (UKA) on short-term clinical outcome. Methods: A total of 116 patients(128 UKAs)underwent UKA in Department of Orthopaedic Surgery of China-Japan Friendship Hospital between January 2014 and December 2015 were retrospectively reviewed. Totally 100 patients (108 UKAs) were finally included in the study. There were 31 males and 69 females, aging from 47 to 90 years (mean 67.2 years). The mean height was (161.9±8.4) cm and the mean body mass index (BMI) was (26.2±3.3) kg/m(2). The posterior tibial slope (PTS) at preoperative and postoperative were measured on the lateral radiograph. The postoperative PTS were divided into five groups (<3°, 3° to 5°, 5° to 7°, 7° to 9° and>9°). The Oxford Knee Score (OKS) was recorded. Pearson correlation analysis, ANOVA and t test were used to analyze data. Results: All operations were successfully accomplished and there were no transfusion, infection, thrombus and other complications. There was 1 patient accepted revision because of bearing dislocation. Compared to preoperative, the PTS decreased (6.5°±2.2° vs.9.6°±3.4°) postoperative, there was statistical difference (t=9.053, P<0.01). Only 3 patients were beyond the recommended range (2° to 12°). A total of 82 patients (86 UKAs) were followed up. The follow-up time was 1 to 2.9 years (mean 2 years). The OKS was 43.0±4.1 (mean 31 to 48). The PTS increased in 12 patients (12 UKAs) postoperative, the mean OKS was 40.5±5.2. The PTS decreased in 70 patients (74 UKAs), the mean OKS was 43.4±3.8. There were significant difference in OKS (t=2.347, P=0.021). There were no significant difference in OKS between the five groups. There were positive correlation between postoperative PTS and preoperative PTS (r=0.201, 95%CI: 0.001 to 0.396, P=0.037), there were no correlations between postoperative PTS and hight and BMI. There were negative correlations between OKS and postoperative PTS (r=-0.255, 95%CI: -0.063 to -0.427, P=0.018) and PTS change (r=-0.292, 95%CI: -0.08 to -0.475, P<0.01). Conclusions: Satisfying PTS can be obtained by use of Oxford MP instrumentation. The clinical outcome of the postoperative PTS decreased was relatively better. Too large posterior slope of the tibial implant should be avoided.

[A comparative study of diagnostic efficacy of different diagnostic/ classification criteria in Takayasu arteritis].

OBJECTIVE: This study aimed to analyze and evaluate the diagnostic efficacy of Ishikawa's, the modified Ishikawa's criteria, 1990 American College of Rheumatology (ACR ) classification criteria and the diagnostic model based on Chinese population in Chinese TA patients. METHODS: One hundred and forty-nine patients with Takayasu arteritis and 126 patients with other vascular disorders which involved aorta or its branches were recruited in this study.All the patients were admitted to the Department of rheumatism and Immunology clinic or inpatient department of Zhongshan Hospital affiliated to Fudan University from January 1(st), 2008 to June 31(st), 2015.General characteristics, clinical manifestations, laboratory results and imaging data of all the patients were collected.Sensitivity, specificity, accuracy and area under receiver operating characteristics (ROC) curve of different criteria were analyzed. RESULTS: Sensitivity, specificity, accuracy and area under ROC curve of Chinese diagnostic model were 90.60%, 80.95%, 86.18%, and 85.80%, respectively, while those of Ishikawa criteria were 34.23%, 99.21%, 64.00%, and 66.70%, respectively.These four indicators of the modified Ishikawa criteria were 84.13%, 79.87%, 81.82%, and 82.00%, respectively and that of ACR criteria were 83.89%, 83.33%, 83.64%, and 83.60%, respectively.No significant difference was found between any two of Chinese diagnostic model, the modified Ishikawa criteria and ACR criteria in all the indicators.Sensitivity of Chinese diagnostic model was highest, while specificity of Ishikawa criteria was the highest.Among these four criteria, the diagnostic efficacy of Chinese model was the best and that of Ishikawa criteria was the worst. CONCLUSION: Chinese diagnostic model, which is based on Chinese population and adopts advanced imaging modality, has better diagnostic efficacy.

Impact of pharmacist intervention on antibiotic use and prophylactic antibiotic use in urology clean operations.

WHAT IS KNOWN AND OBJECTIVE: The use of prophylactic antibiotics in clean operations was routine in China before 2011. Along with the appeal for using antibiotics rationally by WHO in 2011, China launched a national special rectification scheme on clinical use of antibiotics from April that year. The scheme, aimed at achieving rational use of antibiotics, made pharmacists part of the responsible medical team. Our objective was to describe the impacts of pharmacist intervention on the use of antibiotics, particularly in urology clean operations. METHODS: Pharmacists participated in antibiotic stewardship programmes of the hospital and urological clinical work and conducted real-time interventions at the same time from 2011 to 2013. Data on the use of antibiotics between 2010 and 2013 in urology were collected. RESULTS: Comparison of the 2013 data with those of 2010 showed that antibiotic use density [AUD= DDDs*100/(The number of patients who were treated the same period*Average days in hospital). DDDs = Total drug consumption (g)/DDD. DDD is the Defined Daily Dose] decreased by 57·8(58·8%); average antibiotic cost decreased by 246·94 dollars; the cost of antibiotics as a percentage of total drug cost decreased by 27·7%; the rate of use of antibiotics decreased from 100% to 7·3%. WHAT IS NEW AND CONCLUSION: The study illustrates how an antibiotic stewardship programme with pharmacist participation including real-time interventions can promote improved antibiotic-prescribing and significantly decrease costs.

QTLs for rice flag leaf traits in doubled haploid populations in different environments.

Two rice doubled haploid (DH) populations derived from the crosses of ZYQ8/JX17 and CJ06/TN1 were used to detect quantitative trait loci (QTLs) for flag leaf length (FLL), width (FLW), and angle (FLA) under long-day conditions in Hangzhou (subtropical zone) and short-day conditions in Hainan (tropical zone), China. The four parents differed significantly in all 3 traits. FLL was found to be positively correlated with FLW in the 2 populations. A total of 30 QTLs were identified for flag leaf traits, with a contribution to the phenotypic variation of each QTL from 4.49 to 26.30%. Among these, qFLL-4b, qFLW-12, and qFLA-2a showed larger additive effects on the phenotype and explained more variations compared to the other QTLs. qFLL-1a and qFLL-8 were detected in both environments, while qFLL-2, qFLL-3, qFLL-10, qFLL-12, qFLW11, qFLW2, and qFLA8 were novel QTLs, which may be beneficial to rice ideal-type breeding.

Characteristics of synonymous codon usage bias in the beginning region of West Nile virus.

Adaptation in the overall codon usage pattern of West Nile virus (WNV) to that of two hosts was estimated based on the synonymous codon usage value (RSCU). Synonymous codon usage biases for the beginning coding sequence of this virus were also analyzed by calculating the usage fluctuation for each synonymous codon along the target region (the first 270 codon sites of the whole coding sequence of WNV). Adaptation of WNV to Anopheles gambiae regarding the overall codon usage revealed a mixture of synonymous codon usage patterns between this virus and its vector. Regarding the adaptation of WNV to its dead-end host and codon usage, although a mixture of overall codon usage patterns exists, the number of codons with reversed tendency codon usage is lower than that between the virus and its vector. In addition, some codons with low RSCU values for this virus are highly selected in the beginning translation region of WNV, while codons with low RSCU values in this region tend to pair with tRNAs present in low abundance in the host, suggesting that highly selected codons in a specific region in the beginning region of WNV are, to some degree, influenced by the corresponding low tRNA abundance of hosts to regulate the translation speed of the WNV polyprotein.