[Clinical application of complete laparoscopic gastrectomy with function preservation of cardia in gastric carcinoma]

To investigate the feasibility and safety of total laparoscopic cardia function preserving gastrectomy for gastric carcinoma. Clinical data of 10 patients undergoing total laparoscopic cardia function preserving gastrectomy for gastric carcinoma from November 2020 to December 2021 were retrospectively collected. There were 7 males and 3 females. The mean age was (66.1±12.9) years (ranged from 38 to 86 years). All of the 10 patients were successfully performed total laparoscopic cardia function preserving gastrectomy without conversion to laparotomy. The time of digestive tract reconstruction was (24.8±3.3) min (20-30 min), and the intraoperative blood loss was (35±24) ml(20-100 ml). The time of postoperative exhaust was (2.5±0.9) days(2-3 d), the time of postoperative liquid diet was (2.25±0.87) days(2-3 d), postoperative hospital stay was (9.5±2.1) days(6-13 d). No surgical complications such as bleeding, anastomotic fistula or anastomotic stenosis occurred. Postoperative pathology showed that the proximal and distal margins of resected specimens were negative. Patients were followed up for 2 to 15 months, respectively. No death or tumor recurrence and metastasis occurred during the follow-up period. There were no symptoms of reflux after operation. Compared with total gastrectomy and proximal gastrectomy, total laparoscopic cardia function preserving gastrectomy can theoretically reduce the incidence of reflux esophagitis. We used manual suture method for digestive tract reconstruction, which can reduce the application of 2-3 stapling studs and reduce the cost of surgical materials. Compared with subtotal gastrectomy, total laparoscopic cardia function preserving gastrectomy has the advantages of more thorough lymph node dissection, with little residual gastric tissue; therefore, the blood supply is relatively better. The incidence of reflux esophagitis of total laparoscopic cardia function preserving gastrectomy for gastric cancer may was lower than total gastrectomy.

[Clinical epidemiological survey of primary liver cancer in Yunnan province from 2005 to 2014]

Objective: To investigate the clinical characteristics and changing trends of primary liver cancer in Yunnan province from 2005 to 2014, in order to provide theoretical basis for the prevention and treatment of liver cancer in this region. Methods: A retrospective survey was used to select inpatient cases of liver cancer who were initially diagnosed and treated in our hospital from 2005 to 2014 with simple random sampling. Patients socio-demographic and clinicopathological characteristics were extracted by a unified and standardized questionnaire, and the data were statistically analyzed. Results: A total of 1000 cases with liver cancer were included, aged (53.2±11.2) years, with a male-to-female ratio of 5.99/1.00. There was no significant change in the gender and age composition ratio of patients in the past 10 years. The proportion of patients with lower education level (primary or junior high school) were increased from 21.8% to 23.4%, and the proportion of patients with relatively higher education level were decreased from 58% to 38.2% (P<0.001). Smokers and non-smokers patients were decreased and increased from 58.8% to 44.4%, and 41.2% to 55.6% (P<0.001). The proportion of drinker patients were decreased from 46.4% to 35.2%. The proportion of patients with advanced liver cancer (stage C and D) were increased, while the proportion of patients with stage A and B showed a downward trend (P<0.001). The proportion of HBsAg-positive patients showed an upward trend, that is, rising from 69% in 2005 to 82% in 2014 (P=0.043). The proportion of HBeAg-positive patients showed a steady trend (P=0.008). The use rate of ultrasound examination in patients with liver cancer were decreased from 91.0% to 58.0% (P=0.001), while the use rate of computed tomography (CT), MRI, and PET/CT examinations were increased from 81.0% to 84.0% (P=0.05), 0 to 22% (P<0.001), and 0 to 3% (P=0.026) between 2005 to 2014. The proportion of surgical patients were increased (P=0.005), but the proportion of interventional patients did not change significantly (P=0.590). Surgery and interventional therapy were the most common treatment methods, and the proportion of patients treated with surgery over the past 10 years showed an upward trend (P=0.005), while the proportion of interventional therapy remained at a high level with no significant change (P=0.590). Conclusion: In Yunnan province, the incidence of liver cancer increases with age, and the proportion of male with liver cancer is almost six times that of women. Moreover, the low positive rate of alpha-fetoprotein levels and advanced clinical stage in this region are presently the main challenges against the liver cancer prevention and treatment. The application scope of CT, magnetic resonance imaging, PET-CT and other examination methods has gradually expanded, but the treatment methods are still mainly surgery and interventional therapy.

[The IL-6/STAT3 signaling pathway mediated by radiotherapy regulates the expression of PD-L1 in esophageal cancer cells]

Objective: To explore the possible mechanism of radiotherapy regulating the expression of PD-L1 in esophageal carcinoma. Methods: Three esophageal cancer cell lines (Eca109, Kyse150, TE1) were irradiated with different doses of X-rays, and 6 Gy+ AG490 group was set. The mRNA expression of PD-L1 was detected by real-time quantitative polymerase chain reaction (RT-qPCR). The protein expressions of PD-L1, STAT3, p-STAT3 were detected by western blotting and the protein level of IL-6 was detected by ELISA. Results: The mRNA expressions of PD-L1 in Eca109, Kyse150 and TE1 were 2.86±0.30, 960.01±21.27 and 106.78±6.67, higher than 1.07±0.15 in normal esophageal cell line HET-1A (P<0.01). The protein expressions of PD-L1 in Eca109, Kyse150 and TE1 were 0.091±0.036, 1.533±0.079 and 0.914±0.035, higher than 0.063±0.01 in normal esophageal cell line HET-1A (P<0.01). After 48 hours of 6 Gy irradiation, the protein expression levels of PD-L1 in Eca109, Kyse150 and TE1 were 0.135±0.007, 1.66±0.06 and 1.32±0.06, higher than 0.09±0.01, 1.21±0.05 and 0.93±0.03 of the 0 Gy group (P<0.01), while the protein expression levels of p-STAT3 in Eca109, Kyse150 and TE1 were 1.44±0.26, 0.75±0.04 and 1.92±0.17, higher than 0.18±0.05, 0.48±0.02 and 0.36±0.06 of the 0 Gy group (P<0.01). IL-6 protein expression increased significantly after different doses of irradiation (P<0.01). After the IL-6/STAT3 signaling pathway was blocked by the specific inhibitor AG490, the expressions of PD-L1 of Eca109, Kyse150 and TE1 in the 6 Gy+ AG490 groups were 0.11±0.03, 1.07±0.08 and 0.96±0.11, without significant differences of 0.09±0.01, 0.96±0.05 and 0.85±0.09 of the 0 Gy group (P>0.05), while the protein expressions of p-STAT3 were 0.76±0.11, 0.59±0.06 and 0.96±0.12, without significant differences of 0.67±0.08, 0.54±0.06 and 0.84±0.11 of the 0 Gy group (P>0.05). Conclusion: Radiotherapy may regulate the expression of PD-L1 in esophageal cancer cells through IL-6 / STAT3 signaling pathway.

[Clinical effect of minimally invasive duodenum preserving pancreatic head resection for benign and pre-malignant lesions of pancreatic head]

Objective: To examine the clinical effect of minimally invasive duodenum preserving pancreatic head resection(DPPHR) for benign and pre-malignant lesions of pancreatic head. Methods: The clinical data of patients with diagnosis of benign or pre-malignant pancreatic head tumor were retrospectively collected and analyzed,all of them underwent laparoscopic or robotic DPPHR between October 2015 and September 2021 at Division of Gastrointestinal and Pancreatic surgery,Zhejiang Provincial People's Hospital. Thirty-three patients were enrolled with 10 males and 23 females. The age(M(IQR)) was 54(32) years old(range: 11 to 77 years old) with body mass index of 21.9(2.9)kg/m²(range: 18.1 to 30.1 kg/m²). The presenting symptoms included abdominal pain(n=12), Whipple triad(n=2), and asymptomatic(n=19), among them there were 7 patients with hypertension and 1 patient with diabetes mellitus. There were 19 patients diagnosed as American Society of Anesthesiologists class Ⅰ and 14 patient as class Ⅱ. The student t test,U test, χ² test or Fisher exact test was used to compare continuous data or categorized data,respectively. All the perioperative data and metabolic morbidity were analyzed and experiences on minimally invasive DPPHR was concluded. Results: Fourteen patients underwent laparoscopic DPPHR,while the rest of 19 patients received robotic DPPHR. Indocyanine green fluorescence imaging was used in 19 patients to guide operation. Five patients were performed pancreatico-gastrostomy and the rest 28 patients underwent pancreaticojejunostomy. Pathological outcomes confirmed 9 solid pseudo-papillary neoplasms, 9 intraductal papillary mucinous neoplasms, 7 serous cystic neoplasms, 6 pancreatic neuroendocrine tumors, 1 mucous cystic neoplasm, 1 chronic pancreatitis. The operative time was (309.4±50.3) minutes(range:180 to 420 minutes),and the blood loss was (97.9±48.3)ml(range:20 to 200 ml). Eighteen patients suffered from postoperative complications,including 3 patients experienced severe complications(Clavien-Dindo Grade ≥Ⅲ). Pancreatic fistula occurred in 16 patients,including 8 patients with biochemical leak,7 patients with grade B pancreatic fistula and 1 patient with grade C pancreatic fistula. No one suffered from the duodenal necrosis and none perioperative death was occurred. The length of hospital stay was 14(7) days (range:6 to 87 days). The follow-up was 22.6(24.5)months(range:2 to 74 months). None suffered from recurrence or metastasis. During the follow-up,all the patients were free of refractory cholangitis. Moreover,in the term of endocrine dysfunction,no postoperative new onset of diabetes mellitus were observed in the long-term follow-up. However,in the view of exocrine insufficiency,pancreatic exocrine insufficiency and non-alcoholic fatty liver disease (NAFLD) was complicated in 2 and 1 patient,respectively,with the supplement of pancreatic enzyme,steatorrhea and weight loss relieved,but NAFLD was awaited to be seen. Conclusions: Minimally invasive DPPHR is feasible and safe for benign or pre-malignant lesions of pancreatic head. Moreover,it is oncological equivalent to pancreaticoduodenectomy with preservation of metabolic function without refractory cholangitis.

A Computational Model of Protein Induced Membrane Morphology with Geodesic Curvature Driven Protein-Membrane Interface

Continuum or hybrid modeling of bilayer membrane morphological dynamics induced by embedded proteins necessitates the identification of protein-membrane interfaces and coupling of deformations of two surfaces. In this article we developed (i) a minimal total geodesic curvature model to describe these interfaces, and (ii) a numerical one-one mapping between two surface through a conformal mapping of each surface to the common middle annulus. Our work provides the first computational tractable approach for determining the interfaces between bilayer and embedded proteins. The one-one mapping allows a convenient coupling of the morphology of two surfaces. We integrated these two new developments into the energetic model of protein-membrane interactions, and developed the full set of numerical methods for the coupled system. Numerical examples are presented to demonstrate (1) the efficiency and robustness of our methods in locating the curves with minimal total geodesic curvature on highly complicated protein surfaces, (2) the usefulness of these interfaces as interior boundaries for membrane deformation, and (3) the rich morphology of bilayer surfaces for different protein-membrane interfaces.

[Clinical analysis of minimal invasive surgical treatment for pancreatic neuroendocrine tumors]

Objective: To analyze the safety and effectiveness of minimal invasive surgery treating pancreatic neuroendocrine tumors (pNETs), and to summarize surgical characteristics and share experience. Methods: The clinical data of 80 pNETs treated by a single hospital from January 2015 to December 2019 were retrospectively analyzed. The patients were divided into laparoscopic group and robot group. And surgical procedures included pancreaticoduodenectomy (PD), distal pancreatectomy (DP), central pancreatectomy (CP), and tumor enucleation. Results: Of 80 patients, 76 cases (95%) underwent minimal invasive surgery and 4 cases (5%) changed to open surgery. There were 38 females, with median age of 54.4 (20-80) years and median BMI (17.0-38.0) kg/m(2). Among them, 24 patients (31.6%) underwent PD, 36 patients (47.4%) underwent DP, 8 patients (10.5%) underwent CP and 8 patients (10.5%) received tumor enucleation. The postoperative incidence of grade B/C pancreatic fistula was 35.5%, the incidence of abdominal infection was 10.5%, the postoperative bleeding was 7.9%, and the reoperation rate was 6.6%, without perioperative deaths. There was no significant difference in postoperative complications among different surgical methods, including postoperative pancreatic fistula (P=0.396), postoperative bleeding (P=0.297), postoperative abdominal infection (P=0.339) and reoperation (P=0.396). Conclusions: Surgical resection is an effective treatment for pNETs. pNETs are suitable for minimally invasive surgery with earlier stage and smaller tumor diameter. Minimally invasive surgery for pNETs is safe and feasible, and functional preserving surgery could take into consideration.

[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.

[Laparoscopic gastroduodenostomy with manual suture for Billroth Ⅰ anastomosis: a report of 36 cases]

Objective: To examine the clinical efficiency of laparoscopic gastroduodenostomy with BillrothⅠanastomosis with manual suture. Methods: The clinic data of 36 patients with gastric cancer who underwent laparoscopic gastroduodenostomy with Billroth Ⅰ anastomosis from November 2017 to September 2019 in Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital were analyzed retrospectively.There were 22 males and 14 females, aged (64.3±9.3) years(range: 43 to 80 years), underwent complete laparoscopic gastroduodenostomy. The laparoscopic manual suture was used for Billroth Ⅰ anastomosis. Results: All the laparoscopic radical gastrectomy and manual suturing gastroduodenostomy were successfully performed. The operation time was (226.7±40.4) minutes (range: 180 to 320 minutes), including (24.8±7.1) minutes (range: 15 to 48 minutes) for gastroduodenostomy.There was (3.8±0.9) days (range: 2 to 6 days) for anal exhaust, (5.7±2.0) days (range: 3 to 13 days) for extubation of gastric tube, and (10.3±3.1) days (range: 7 to 19 days) for hospitalization. There was no death in perioperative period. Postoperative pathological report showed 3 cases of highly differentiated adenocarcinoma, 5 cases of moderately differentiated adenocarcinoma, 22 cases of poorly differentiated adenocarcinoma and 6 cases of signet ring cell carcinoma, including 27 cases in T1 stage and 9 cases in T2 stage. The number of lymph nodes harvested was 36.4±8.9 (range: 23 to 60). Lymph node metastasis was positive in 7 cases and negative in 29 cases. TNM stage included 24 cases in ⅠA stage, 8 cases in ⅠB stage and 4 cases in Ⅱ stage. After the operation, the upper digestive tract radiography showed that the anastomosis opening was unobstructed without complications such as anastomotic stenosis. Conclusion: Laparoscopic gastroduodenostomy with Billroth Ⅰ anastomosis with manual suture is safe and feasible, has a good short-term effect.

The antibiofilm and collagen-stabilizing effects of proanthocyanidin as an auxiliary endodontic irrigant

AIM

To evaluate the antibiofilm effect of proanthocyanidin (PA) solution as an irrigant against Enterococcus faecalis (E. faecalis) and its influence on the mechanical properties and biodegradation resistance of demineralized root dentine.

METHODOLOGY

Enterococcus faecalis were introduced into human root dentine tubules by a serial centrifugation method and grown for 1 week. Dentine blocks infected with 1-week-old E. faecalis biofilms were treated with the following irrigants: sterile water (control), 2% chlorhexidine (CHX), 2% PA, 5% PA and 10% PA. After treatment, the live and dead bacteria proportions within E. faecalis biofilms were analysed using confocal laser scanning microscopy. To evaluate the biostability of fully demineralized dentine treated by the aforementioned irrigants, the elastic modulus and hydroxyproline release of human dentine incubated in collagenase solution were tested at baseline, after irrigant treatment and after biodegradation, respectively. Furthermore, the surface chemical bond of demineralized dentine collagen treated by various irrigants was characterized by X-ray photoelectron spectroscopy (XPS). Statistical analysis was performed using one-way anova and Tukey's post hoc multiple comparisons with the significance level at 5%.

RESULTS

The proportion of dead E. faecalis volume was significantly higher in the PA and CHX groups than that in the control group (P < 0.05). PA irrigation significantly increased the mechanical properties of demineralized dentine (P < 0.05), and the effect was enhanced with increasing PA concentration. CHX and PA groups had significantly less elasticity loss and hydroxyproline release (P < 0.05). The biomodification of dentine collagen by PA was verified by increased C-O/C-N peak percentage under C1s and C-O peak percentage under O1s narrow-scan XPS spectra.

CONCLUSIONS

Proanthocyanidin killed E. faecalis within biofilms and enhanced the biostability of the collagen matrix of demineralized root dentine. It might be used as an auxiliary endodontic irrigant with antibiofilm and collagen-stabilizing effects.

[Clinical characteristics and prognosis of high-risk neuroblastoma with bone marrow metastasis in children]

Objective: To analyze the clinical characteristics of newly treated high-risk group neuroblastoma (NB) patients with bone marrow metastasis and to explore the prognostic factors. Methods: The clinical features (sex, age, stage, risk group, pathological type, metastatic site, etc.) of 203 newly treated high-risk NB patients with bone marrow metastasis admitted to Hematology Oncology Center, Beijing Children's Hospital from January 2007 to December 2016 were analyzed retrospectively. There were 118 males (58.1%) and 85 females (41.9%). Kaplan-Meier method was used for survival analysis and Cox regression was used to analyze the prognostic factors. Results: The age at onset of the 203 patients was 41 months (9-147 months). The metastatic sites at diagnosis were as follows: bone in 195 cases (96.1%), distant lymph nodes in 104 cases (51.2%), skull and endomeninx in 61 cases (30.0%), orbit in 30 cases (14.8%), pleura in 16 cases (7.9%), liver in 13 cases(6.4%), canalis spinalis in 13 cases (6.4%), other sites in 11 cases (5.4%) and skin and soft tissue in 10 cases (4.9%). In all, 194 cases were enrolled for prognostic analysis. The follow-up time was 36 months (1 day-138 months) , and the 5-years event free survival (EFS) and overall survival (OS) were 36.1% and 39.7%, respectively. A total of 118 patients (60.8%) had events (first relapse or death) with the time to event occurrence was 15 months (1 day-72 months), whereas 112 patients (57.7%) died with the event occurrence to death time was 3 months (1 day-21 months). There was no significant difference in 5-years OS between radiotherapy group and non-radiotherapy group (42.3% vs. 38.3%, χ(2)=3.671, P=0.055). The 5-years OS in transplantation group was significantly better than the non-transplantation group (44.3% vs. 35.5%, χ(2)=8.878, P=0.003), and the radiotherapy combined transplantation group also had a better 5-years OS rate than the non-radiotherapy combined transplantation group (45.8% vs. 37.3%, χ(2)=5.945, P=0.015). Univariate survival analysis showed lactate dehydrogenase ≥ 1 500 U/L, the amplification of MYCN, the metastatic sites of orbit, canalis spinalis and pleura were associated with poor prognosis of newly diagnosed high-risk NB patients (χ(2)=21.064, 13.601, 3.998, 6.183, 15.307, all P<0.05). The amplification of MYCN and the metastatic sites of pleura were risk factors for prognosis of newly diagnosed high-risk NB patients by Cox regression models (HR=1.896,1.100, 95%CI: 1.113-3.231, 1.020-1.187, both P<0.05). Conclusions: The prognosis is unfavorable in high-risk group NB patients with BM metastasis. Radiotherapy combined with transplantation can further improve the prognosis of these patients. The amplification of MYCN and the metastatic sites of pleura were the poor prognostic factors for high-risk NB patients with bone marrow metastasis.

[Preliminary application of endoscopic titanium clip localization combined with three-dimensional CT reconstruction in the determination of resection margin of gastric central cancer under laparoscopy]

Objective: To evaluate the accuracy of endoscopic titanium clip localization combined with CT three-dimensional reconstruction for the control of incision margin in early gastric cancer under laparoscopy. Methods: A prospective analysis was made for gastric cancer whose lesions were located in the middle of the stomach and T stage was 1 to 2 from October 2017 to January 2019 at Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital. Totally 25 patients were eventually enrolled in the study. There were 17 males and 8 females aging of (63.6± 7.2) years (range: 48 to 77 years). All cases were treated with titanium clip localization under endoscope combined with CT three-dimensional (3D) reconstruction to construct a virtual panorama of gastric cavity and lesions, and to design surgical margins. Laparoscopic surgical resection was performed according to the surgical margins designed before operation. The distance from the gastric angle to the origin of the minor curvature of the incisional margin, the distance from the gastric angle to the the center of lesion and the distance of the upper incision margin were measured under three-dimensional CT reconstruction and under actual specimen. Paired t test was used to compare the three distances measured by two methods. Results: The measured distances from the gastric angle to the center of the lesion and the proximal incisional margin under 3D reconstruction CT were according to the measured values of actual specimens ((2.67±1.38) cm vs. (2.83±1.56) cm, t=1.51, P=0.14; (5.23±0.60) cm vs. 5 cm, t=1.93, P=0.07); the measured distances from the gastric angle to the origin of the minor curvature of the incisional margin under CT 3D reconstruction were different with the measured values of solid specimens ((5.94±0.94) cm vs. (6.37±0.90) cm, t=3.52, P=0.00). Conclusion: The method of titanium clip localization combined with CT 3D reconstruction can provide a feasible laparoscopic localization method and incision edge solution for T1 to 2 gastric central cancer.

[Laparoscopic radical antegrade modular pancreatosplenectomy for left-sided pancreatic adenocarcinoma: analysis of 12 cases]

Objective: To evaluate the safety and feasibility of laparoscopic radical antegrade modular pancreatosplenectomy(Lap-RAMPS) for left-sided pancreatic adenocarcinoma. Methods: Clinical data of total 12 patients underwent Lap-RAMPS for left-sided pancreatic adenocarcinoma at Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital from March 2016 to August 2017 were reviewed retrospectively.There were 7 male patients and 5 female patients, with median age of 60.5 years old(47-68 years old). Abdominal enhanced CT, pancreatic MRI, PET-CT were performed on all patients to evaluate the lesion and exclude metastasis.Follow-up were done with out-patient clinic or telephone consultancy until October 2017. Results: All patients underwent pure Lap-RAMPS.The medium operative time was 250 minutes(180-445 minutes), and the blood loss was 150 ml(50-500 ml). The medium first flatus time and diet resumption time were 3.0 days(1-5 days) and 3.5 days(1-7 days) respectively.The medium postoperative hospital stay was 9 days(4-18 days). Morbidity occurred in 8 patients with gastric empty delay(n=1), bleeding(n=1), fluid collection(n=3). There was no mortality.The medium overall number of retrived lymph nodes was 15.6 and the positive rate was 41.7%. The R0 rate was 100%.The medium follow-up was 10 months.One patient was diagnosed as liver metastasis after 8 months and accepted chemotherapy.One patient died after 14 months for tumor recurrence and metastasis.Others survived without tumor recurrence or metasitasis. Conclusion: Lap-RAMPS is safe and feasible with accepted oncological outcomes for selected left side pancreatic adenocarcinoma under skilled hands.

[Experience on postoperative complications of laparoscopic pancreaticoduodenectomy]

Objective: To summarize the incidence and characteristics of postoperative complications after laparoscopic pancreaticoduodenectomy(LPD), and to share our experience on management of complications. Methods: The clinical data of 320 LPD performed by a single team in Sir Run Run Shaw Hospital and Zhejiang Provincial People's Hospital between September 2012 and September 2017 were retrospectively analyzed, among which there were 196 males and 124 females with age of (60.2±11.6) years old.There were 306 patients who underwent standard LPD, and 14 patients who underwent extended LPD. The patients were divided into 2 groups of former 160 LPD and later 160 LPD according to the time order. By analyzing the differences of clinical outcomes between the two groups, especially focusing on the incidence of postoperative complications.The experience on management of complications was concluded. The prior surgical history of latter group was significantly higher than the former group(30.0%(48/160)vs. 18.8%(30/160), χ(2)=5.49, P=0.019), and the rest of baseline characteristics remained the comparable (P>0.05). For resectable lesions, LPD was performed by "No back" approach, following the principle of "From distal to cephalad, from ventral to dorsal, and from left to right" . As for the borderline resectable patients, LPD was performed by "Easy first" strategy. Student t test, χ(2) test or Fisher test was used to analyzed the data between the two groups respectively. Results: Of 320 LPD patients, 306 cases underwent standard LPD, 14 cases underwent LPD with resection of other organs.There were 278 LPD cases who followed "No back" approach, and 42 cases who followed "Easy first" strategy because of difficulty in creating the retro-pancreatic tunnel. And the overall morbidity was 32.2%(103/320) with reoperation rate of 5.3%(17/320). The perioperative mortality was 0.6%(2/320). The operation time of latter group was ((346.6±48.8)minutes), which was shorter than that of former group((358.0±54.4)minutes)(t=1.97, P=0.048). The blood loss of former and latter group remained comparable((207.9±135.8)ml vs.(189.6±121.4)ml, P=0.205). However, in subgroup analysis, the patients with blood loss less <200 ml of latter group decreased significantly from 59.4%(95/160) to 47.5%(76/160)(χ(2)=4.53, P=0.033). The overall morbidity of latter group was 28.8%(46/160), indicated a decrease from 35.6%(57/160) of former group without significant difference(P=0.188). Moreover, Grade A/B/C pancreatic fistula rate, Grade A/C bile leakage rate, Grade B/C postoperative hemorrhage rate of the later group tended to decrease, although they also didn't reach a significant difference. However, the abdominal infection rate decreased significantly(χ(2)=3.93, P=0.047). The length of hospital stay remained comparable(P=0.156). Conclusions: The most common complications after LPD were postoperative hemorrhage and pancreatic fistula. With specialized team and accumulated experience, the morbidity can decrease progressively by analyzing the leading cause and improving the technical skills.

The importance of mechanical constraints for proper polarization and psuedo-cleavage furrow generation in the early Caenorhabditis elegans embryo

Intracellular polarization, where a cell specifies a spatial axis by segregation of specific factors, is a fundamental biological process. In the early embryo of the nematode worm Caenorhabditis elegans (C. elegans), polarization is often accompanied by deformations of the cortex, a highly contractile structure consisting of actin filaments cross-linked by the motor protein myosin (actomyosin). It has been suggested that the eggshell surrounding the early embryo plays a role in polarization although its function is not understood. Here we develop a mathematical model which couples a reaction-diffusion model of actomyosin dynamics with a phase field model of the cell cortex to implicitly track cell shape changes in the early C. elegans embryo. We investigate the potential rigidity effect of the geometric constraint imposed by the presence and size of the eggshell on polarization dynamics. Our model suggests that the geometric constraint of the eggshell is essential for proper polarization and the size of the eggshell also affects the dynamics of polarization. Therefore, we conclude that geometric constraint on a cell might affect the dynamics of a biochemical process.

Polarization, whereby molecules and proteins are asymmetrically distributed throughout the cell, is a vital process for many cellular functions. In the early C. elegans embryo the asymmetric distribution of cell cytoskeleton during the initiation of polarization leads to asymmetric contractions which are higher in the anterior and lower in the posterior of a cell. The C. elegans embryo is surrounded by a rigid body, the eggshell, which functions in numerous cell processes. We investigate the structural support of eggshell during the establishment phase by tracking the moving cell surface. We incorporate protein dynamics involved in polarization into the membrane evolution. We conclude that eggshell might have a role in cell polarization by preventing the distortion of cell surface.

[Strategy in management of adjacent organ lesion during laparoscopic pancreaticoduodenectomy]

Objective: To evaluate the safety and feasible of adjacent organ resection during laparoscopic pancreaticoduodenectomy(LPD), and summary the surgical strategies. Methods: Clinical data of 15 adjacent organ resections combined with LPD from March 2013 to September 2017 were reviewed.There were 10 male and 5 female patients aging from 20 to 86 years, and the body mass index ranged from 19.6 to 34.5 kg/m(2).Two patients had previous abdominal surgical history.Two patients underwent preoperative chemotherapy. Results: The resected adjacent organs included liver(n=4), stomach(n=3), colon(n=6), right kidney with embolectomy and vasoplastic of inferior vena cava(n=1), and spleen artery aneurysms(n=1). The operative time ranged from 280 to 450 minutes, and the blood loss ranged from 100 to 450 ml.The total complication rate was 5/15 and no one died in 90 days after surgery.The postoperative hospital stay ranged from 10 to 42 days with medium 18 days.The pathology included adenocarcinoma of stomach and duodenum(n=1), gastric cancer invading pancreas or duodenum(n=2), ampullary adenocarcinoma with left hepatolithiasis(n=1), ampullary adenocarcinoma with a benign lesion in left liver(n=1), ampullary adenocarcinoma with single liver metastasis(n=1), ampullary adenocarcinoma(n=1), pancreatic intraductal papillary mucinous neoplasm with splenic artery aneurysms(n=1), pancreatic neuroendocrine neoplasm with colon cancer(n=1), distal common bile duct adenocarcinoma involving righ hepatic duct(n=1), pancreatic neuroendocrine neoplasm invading inferior vena cava and right renal vein(n=1), duodenal adnocarcinoma(n=1), duodenal ewing's sarcoma(n=1), duodenal intesititialoma(n=2). The follow-up was from 3 to 40 months with the medium survival of 17.5 months. Conclusions: The oncological outcomes of PD combined with adjacent organ resection is acceptable.Surgical treatment for those patients with periampullary neoplasma and adjacent organ lesions should be aggressive.

Geodesic curvature driven surface microdomain formation

Lipid bilayer membranes are not uniform and clusters of lipids in a more ordered state exist within the generally disorder lipid milieu of the membrane. These clusters of ordered lipids microdomains are now referred to as lipid rafts. Recent reports attribute the formation of these microdomains to the geometrical and molecular mechanical mismatch of lipids of different species on the boundary. Here we introduce the geodesic curvature to characterize the geometry of the domain boundary, and develop a geodesic curvature energy model to describe the formation of these microdomains as a result of energy minimization. Our model accepts the intrinsic geodesic curvature of any binary lipid mixture as an input, and will produce microdomains of the given geodesic curvature as demonstrated by three sets of numerical simulations. Our results are in contrast to the surface phase separation predicted by the classical surface Cahn-Hilliard equation, which tends to generate large domains as a result of the minimizing line tension. Our model provides a direct and quantified description of the structure inhomogeneity of lipid bilayer membrane, and can be coupled to the investigations of biological processes on membranes for which such inhomogeneity plays essential roles.

CURVATURE-DRIVEN MOLECULAR FLOW ON MEMBRANE SURFACE

This work presents a mathematical model for the localization of multiple species of diffusion molecules on membrane surfaces. Morphological change of bilayer membrane in vivo is generally modulated by proteins. Most of these modulations are associated with the localization of related proteins in the crowded lipid environments. We start with the energetic description of the distributions of molecules on curved membrane surface, and define the spontaneous curvature of bilayer membrane as a function of the molecule concentrations on membrane surfaces. A drift-diffusion equation governs the gradient flow of the surface molecule concentrations. We recast the energetic formulation and the related governing equations by using an Eulerian phase field description to define membrane morphology. Computational simulations with the proposed mathematical model and related numerical techniques predict (i) the molecular localization on static membrane surfaces at locations with preferred mean curvatures, and (ii) the generation of preferred mean curvature which in turn drives the molecular localization.

[Laparoscopic pancreaticoduodenectomy: a report of 233 cases by a single team]

Objective: To summary the experience of 233 cases of laparoscopic pancreaticoduodenectomy (LPD) performed by a single surgical team. Methods: Data of patients undergoing LPD from September 2012 to October 2016 were reviewed. There were 145 males and 88 females with the mean age of(60.3±13.0)years old, ranging from 19 to 92 years old, and the mean body mass index of (22.8±3.5)kg/m(2,) ranging from 16.3 to 36.8 kg/m(2). There were 195 patients with clinical manifestation and 54 patients who had the history of abdominal surgery. Results: LPD were performed on 233 patients by same surgical team consecutively. The mean operative time was(368.0±57.4)minutes. Mean blood loss was(203.8±138.6)ml. The postoperative morbidity rate was 33.5%, with 6.9% of grade B or C pancreatic fistula and 9.9% of bleeding. The reoperation rate was 5.6%. The mortality during 30 days after operation was 0.9%. Mean postoperative hospital stay was (18.1±11.2)days. Mean tumor size was (3.9±2.4)cm, and the mean number of lymph nodes harvested was 21.3±11.9.One hundred and sixty-three patients were diagnosed as malignant tumor, including pancreatic adenocarcinoma(n=84), cholangiocarcinoma(n=17), ampullary adenocarcinoma(n=55), duodenal adenocarcinoma(n=5), gastric cancer(n=1)and duel cancer (n=1) located in distal stomach and duodenum. Conclusion: The key point to make laparoscopic pancreaticduodenectomy a routine safe procedure is to operate the procedure under skilled hands in selected patients via suitable surgical approaches.

[Estradiol stimulates the growth and biofilm formation of clinical Staphylococcus epidermidis]

Objective: To investigate the effect of steroid hormones on the growth and biofilm formation of S. epidermidis. Methods: In all experiments, two S. epidermidis standard strains (ATCC12228 and ATCC35984) and two S. epidermidis clinical strains (SE101 and SE40) were incubated on the surface of silica gel in estradiol concentrations of 0, 50, 125, 250 and 500 pmol/L at 4, 6, 12, 24, 48 and 72 hours. Growth curve were drawn by means of the OD value. Formed biofilms were assessed by crystal violet staining methods. In order to observe the processes and structures of biofilm, the confocal laser scanning microscopy (CLSM) and scanning electron microscope (SEM) were used. Results: All of the four strains which were incubated with the concentrations of 125 pmol/L of estradiol had entered the logarithmic growth stage ahead of the blank control (3 h and 4 h). Crystal violet staining indicated that there was no biofilm for ATCC12228. Improved primary attachment abilities were found for ATCC35984 and SE101 in the presence of estradiol, and the OD values were 0 pmol/L (0.081±0.015 and 0.082±0.011), 50 pmol /L (0.087±0.013 and 0.088±0.010), 125 pmol/L (0.175±0.052 and 0.091±0.012), 250 pmol/L (0.153±0.036 and 0.090±0.006), 500 pmol/L (0.157±0.050 and 0.082±0.032), respectively. The thickness of biofilm reached the peak in 125 pmol/L estradiol at 24 h. CLSM and SEM found estradiol promoted the biofilm maturity and the biofilm of 125 pmol/L group was denser and thicker than that of the other concentration groups. Conclusions: Our in vitro experiments indicate that estradiol could promote the growth of S. epidermidis which exit on the surface of silica gel, and improve the ability of biofilm formation of S. epidermidis.

Ferroelectric-gate thin-film transistors with Bi3.15Nd0.85Ti3O12 gate insulators on LaNiO3-buffered Si substrates

Ferroelectric-gate thin-film transistors (FGTs) with a stacked oxide structure of ZnO/Bi_3.15Nd_0.85Ti₃O₁₂ (BNT)/LaNiO₃ (LNO) on Si substrates have been prepared and characterized.

Characterization of yellow grouper Epinephelus awoara (Serranidae) karyotype by chromosome bandings and fluorescence in situ hybridization

The cytogenetics of yellow grouper Epinephelus awoara was studied using multiple cytogenetic markers [Giemsa staining, C-banding, Ag-NORs and fluorescence in situ hybridization (FISH)]. Giemsa staining results showed that the karyotypic formula of E. awoara was 2n = 48a, FN (fundamental number) = 48. Faint C-bandings were only detected at the centromeric regions of chromosome pair number 24, being almost indiscernible on the other chromosome pairs. After Ag-NOR staining, one pair of nucleolar organizer regions (NOR) was observed in the subcentromeric region of pair number 24. FISH results showed that 5S rDNA was located at a pair of medium-sized chromosomes, while 18S rDNA appeared at the same location in the subcentromeric region of pair number 24 where Ag-NORs were detected. The telomeric sequence (TTAGGG)(n) detected by FISH was located at both ends of each chromosome. The results suggested that E. awoara has retained general karyotypic structure stability during the evolutionary diversification process.

A rare Y chromosome constitutional rearrangement: a partial AZFb deletion and duplication within chromosome Yp in an infertile man with severe oligoasthenoteratozoospermia

We report a case of an infertile man with severe oligoasthenoteratozoospermia with a partial azoospermia factor b (AZFb) deletion and duplication region within chromosome Yp11.2. The hormonal profile was normal for serum concentrations of follicle-stimulating hormone, luteinizing hormone, testosterone and oestradiol. The patient, who showed a 46,XY karyotype, had an approximate 2.4 Mb inherited duplication region in Yp11.2 and a de novo partial AZFb deletion, which spanned 5.25 Mb including eight protein coding genes and four non-coding transcripts, but did not remove the RBMY gene family. Both proximal and distal breakpoints of the deletion were outside any palindromic region or inverted repeat sequence and intra-chromosomal non-allelic homologous recombination could not have been the deletion mechanism. The partial AZFb deletion in our case diminished sperm production, but did not completely extinguish spermatogenesis. Considering severe oligozoospermia, spermatozoa in the patient's ejaculate were used for intracytoplasmic sperm injection, resulting in two twin pregnancies.

Poisson-Nernst-Planck equations for simulating biomolecular diffusion-reaction processes II: size effects on ionic distributions and diffusion-reaction rates

The effects of finite particle size on electrostatics, density profiles, and diffusion have been a long existing topic in the study of ionic solution. The previous size-modified Poisson-Boltzmann and Poisson-Nernst-Planck models are revisited in this article. In contrast to many previous works that can only treat particle species with a single uniform size or two sizes, we generalize the Borukhov model to obtain a size-modified Poisson-Nernst-Planck (SMPNP) model that is able to treat nonuniform particle sizes. The numerical tractability of the model is demonstrated as well. The main contributions of this study are as follows. 1), We show that an (arbitrarily) size-modified PB model is indeed implied by the SMPNP equations under certain boundary/interface conditions, and can be reproduced through numerical solutions of the SMPNP. 2), The size effects in the SMPNP effectively reduce the densities of highly concentrated counterions around the biomolecule. 3), The SMPNP is applied to the diffusion-reaction process for the first time, to our knowledge. In the case of low substrate density near the enzyme reactive site, it is observed that the rate coefficients predicted by SMPNP model are considerably larger than those by the PNP model, suggesting both ions and substrates are subject to finite size effects. 4), An accurate finite element method and a convergent Gummel iteration are developed for the numerical solution of the completely coupled nonlinear system of SMPNP equations.

Effect of daidzein on egg-laying performance in Shaoxing duck breeders during different stages of the egg production cycle

The effect of a phyto-oestrogen, daidzein, on the laying performance of Shaoxing female ducks was examined in three experiments performed at different stages of the egg production cycle. Egg-laying rate, egg weight, egg composition, feed conversion ratio, hatchability characteristics of eggs and body weight, ovary and oviduct weight, as well as changes in serum concentrations of T3, T4 and E2 were recorded as response criteria. In the first experiment, 68 young ducks, 100 d of age, were given a basal diet (maize-soybean meal) with or without 3 mg of daidzein/kg diet for 42 d. Daidzein did not affect the onset of lay but apparently decreased egg-laying rate and mean egg weight as well as the feed conversion ratio. In the second experiment, 240 breeding ducks, 402 d of age, were allotted at random to three groups and given the basal diet containing daidzein at 0 (control), 3 (Da1) and 5mg/kg (Da2) for 35d. Egg-laying rate, mean egg weight and feed conversion ratio increased in both Da1 and Da2 groups. However, an adverse effect of daidzein on fertility and hatchability was observed. In the third experiment, 320 breeding ducks, 415 d of age, were fed on the basal diet with or without 5mg of daidzein/kg diet for 63 d. Egg-laying rate increased by 7.7%, average egg weight tended to increase, whereas yolk/albumen ratio decreased. Daidzein-treated ducks had higher body weight and oviduct weight compared with their controls. Elevated plasma T4 and E2 concentrations accompanied these phenotypic changes, but serum T3 was not affected. It is suggested that daidzein exerts divergent effects on the egg-laying performance of Shaoxing ducks under different physiological conditions and this action is dose-dependent. The changes in circulating E2 imply possible participation of endogenous oestrogen in the mechanism of daidzein action.

Continuum electromechanical modeling of protein-membrane interactions

A continuum electromechanical model is proposed to describe the membrane curvature induced by electrostatic interactions in a solvated protein-membrane system. The model couples the macroscopic strain energy of membrane and the electrostatic solvation energy of the system, and equilibrium membrane deformation is obtained by minimizing the electroelastic energy functional with respect to the dielectric interface. The model is illustrated with the systems with increasing geometry complexity and captures the sensitivity of membrane curvature to the permanent and mobile charge distributions.

Poisson-Nernst-Planck Equations for Simulating Biomolecular Diffusion-Reaction Processes I: Finite Element Solutions

In this paper we developed accurate finite element methods for solving 3-D Poisson-Nernst-Planck (PNP) equations with singular permanent charges for electrodiffusion in solvated biomolecular systems. The electrostatic Poisson equation was defined in the biomolecules and in the solvent, while the Nernst-Planck equation was defined only in the solvent. We applied a stable regularization scheme to remove the singular component of the electrostatic potential induced by the permanent charges inside biomolecules, and formulated regular, well-posed PNP equations. An inexact-Newton method was used to solve the coupled nonlinear elliptic equations for the steady problems; while an Adams-Bashforth-Crank-Nicolson method was devised for time integration for the unsteady electrodiffusion. We numerically investigated the conditioning of the stiffness matrices for the finite element approximations of the two formulations of the Nernst-Planck equation, and theoretically proved that the transformed formulation is always associated with an ill-conditioned stiffness matrix. We also studied the electroneutrality of the solution and its relation with the boundary conditions on the molecular surface, and concluded that a large net charge concentration is always present near the molecular surface due to the presence of multiple species of charged particles in the solution. The numerical methods are shown to be accurate and stable by various test problems, and are applicable to real large-scale biophysical electrodiffusion problems.

Considerable Enhancement of Field Emission of SnO(2) Nanowires by Post-Annealing Process in Oxygen at High Temperature

The field emission properties of SnO(2) nanowires fabricated by chemical vapor deposition with metallic catalyst-assistance were investigated. For the as-fabricated SnO(2) nanowires, the turn-on and threshold field were 4.03 and 5.4 V/mum, respectively. Considerable enhancement of field emission of SnO(2) nanowires was obtained by a post-annealing process in oxygen at high temperature. When the SnO(2) nanowires were post-annealed at 1,000 degrees C in oxygen, the turn-on and threshold field were decreased to 3.77 and 4.4 V/mum, respectively, and the current density was increased to 6.58 from 0.3 mA/cm(2) at the same applied electric field of 5.0 V/mum.

Cluster characterization of mouse embryonic stem cell-derived pluripotent embryoid bodies in four distinct developmental stages

The formation of embryoid bodies (EBs) is the principal step in the differentiation of embryonic stem (ES) cells. In this study, the morphological characteristics and gene expression patterns of EBs related to the sequential stages of embryonic development were well defined in four distinct developmental groups over 112 days of culture: early-stage EBs groups (1-7 days of differentiation), mid-stage EBs groups (9-15 days of differentiation), maturing EBs groups (17-45 days of differentiation) and matured EBs groups (50 days of differentiation). We first determined definite histological location of apoptosis within EBs and the sequential expression of molecular markers representing stem cells (Oct4, SSEA-1, Sox-2 and AKP), germ cells (Fragilis, Dazl, c-kit, StellaR, Mvh and Stra8), ectoderm (Neurod, Nestin and Neurofilament), mesoderm (Gata-1, Flk-1 and Hbb) and endoderm (AFP and Transthyretin). Our results revealed that developing EBs possess either pluripotent stem cell or germ cell states and that three-dimensional aggregates of EBs initiate mES cell differentiation during prolonged culture in vitro. Therefore, we suggest that this EB system to some extent recapitulates the early developmental processes occurring in vivo.

A Nonlinear Elasticity Model of Macromolecular Conformational Change Induced by Electrostatic Forces

In this paper we propose a nonlinear elasticity model of macromolecular conformational change (deformation) induced by electrostatic forces generated by an implicit solvation model. The Poisson-Boltzmann equation for the electrostatic potential is analyzed in a domain varying with the elastic deformation of molecules, and a new continuous model of the electrostatic forces is developed to ensure solvability of the nonlinear elasticity equations. We derive the estimates of electrostatic forces corresponding to four types of perturbations to an electrostatic potential field, and establish the existance of an equilibrium configuration using a fixed-point argument, under the assumption that the change in the ionic strength and charges due to the additional molecules causing the deformation are sufficiently small. The results are valid for elastic models with arbitrarily complex dielectric interfaces and cavities, and can be generalized to large elastic deformation caused by high ionic strength, large charges, and strong external fields by using continuation methods.

Continuum simulations of acetylcholine consumption by acetylcholinesterase: a Poisson-Nernst-Planck approach

The Poisson-Nernst-Planck (PNP) equation provides a continuum description of electrostatic-driven diffusion and is used here to model the diffusion and reaction of acetylcholine (ACh) with acetylcholinesterase (AChE) enzymes. This study focuses on the effects of ion and substrate concentrations on the reaction rate and rate coefficient. To this end, the PNP equations are numerically solved with a hybrid finite element and boundary element method at a wide range of ion and substrate concentrations, and the results are compared with the partially coupled Smoluchowski-Poisson-Boltzmann model. The reaction rate is found to depend strongly on the concentrations of both the substrate and ions; this is explained by the competition between the intersubstrate repulsion and the ionic screening effects. The reaction rate coefficient is independent of the substrate concentration only at very high ion concentrations, whereas at low ion concentrations the behavior of the rate depends strongly on the substrate concentration. Moreover, at physiological ion concentrations, variations in substrate concentration significantly affect the transient behavior of the reaction. Our results offer a reliable estimate of reaction rates at various conditions and imply that the concentrations of charged substrates must be coupled with the electrostatic computation to provide a more realistic description of neurotransmission and other electrodiffusion and reaction processes.

Electrodiffusion: a continuum modeling framework for biomolecular systems with realistic spatiotemporal resolution

A computational framework is presented for the continuum modeling of cellular biomolecular diffusion influenced by electrostatic driving forces. This framework is developed from a combination of state-of-the-art numerical methods, geometric meshing, and computer visualization tools. In particular, a hybrid of (adaptive) finite element and boundary element methods is adopted to solve the Smoluchowski equation (SE), the Poisson equation (PE), and the Poisson-Nernst-Planck equation (PNPE) in order to describe electrodiffusion processes. The finite element method is used because of its flexibility in modeling irregular geometries and complex boundary conditions. The boundary element method is used due to the convenience of treating the singularities in the source charge distribution and its accurate solution to electrostatic problems on molecular boundaries. Nonsteady-state diffusion can be studied using this framework, with the electric field computed using the densities of charged small molecules and mobile ions in the solvent. A solution for mesh generation for biomolecular systems is supplied, which is an essential component for the finite element and boundary element computations. The uncoupled Smoluchowski equation and Poisson-Boltzmann equation are considered as special cases of the PNPE in the numerical algorithm, and therefore can be solved in this framework as well. Two types of computations are reported in the results: stationary PNPE and time-dependent SE or Nernst-Planck equations solutions. A biological application of the first type is the ionic density distribution around a fragment of DNA determined by the equilibrium PNPE. The stationary PNPE with nonzero flux is also studied for a simple model system, and leads to an observation that the interference on electrostatic field of the substrate charges strongly affects the reaction rate coefficient. The second is a time-dependent diffusion process: the consumption of the neurotransmitter acetylcholine by acetylcholinesterase, determined by the SE and a single uncoupled solution of the Poisson-Boltzmann equation. The electrostatic effects, counterion compensation, spatiotemporal distribution, and diffusion-controlled reaction kinetics are analyzed and different methods are compared.

Highly accurate biomolecular electrostatics in continuum dielectric environments

Implicit solvent models based on the Poisson-Boltzmann (PB) equation are frequently used to describe the interactions of a biomolecule with its dielectric continuum environment. A novel, highly accurate Poisson-Boltzmann solver is developed based on the matched interface and boundary (MIB) method, which rigorously enforces the continuity conditions of both the electrostatic potential and its flux at the molecular surface. The MIB based PB solver attains much better convergence rates as a function of mesh size compared to conventional finite difference and finite element based PB solvers. Consequently, highly accurate electrostatic potentials and solvation energies are obtained at coarse mesh sizes. In the context of biomolecular electrostatic calculations it is demonstrated that the MIB method generates substantially more accurate solutions of the PB equation than other established methods, thus providing a new level of reference values for such models. Initial results also indicate that the MIB method can significantly improve the quality of electrostatic surface potentials of biomolecules that are frequently used in the study of biomolecular interactions based on experimental structures.

[Studies on the sex difference in proteins between male and female adult worm of Schistosoma japonicum]

OBJECTIVE

To explore the sex difference in proteins between male and female adult worm of Schistosoma japonicum.

METHODS

Two-electrophoresis was used to analyse the difference of protein between the male and female adult worm of S. japonicum (Chinese strain).

RESULTS

Two-dimensional electrophoresis analysis revealed that at the site of 43 kDa and an isoelectric point (pI) of 5.60-5.90 the male worm exhibited a band carrying a number of spots and dots, being longer and wider than that exhibited by the female worm. The female worm exhibited 7 specific dots.

CONCLUSION

The sex differences in proteins between male and female adult worms of S. japonicum are significant.