Objective To investigate the value of detecting hepatitis B virus (HBV) YMDD variants by matrix-assisted laser de-sorption time of flight mass spectrometry (MALDI-TOF MS). Methods The assay is based on polymerase chain reaction (PCR) amplifica-tion and mass measurement of oligonucleotides containing sites of mutation of the YMDD motif. Result The MALDI-TOF MS-based genoty-ping assay was sufficiently sensitive to detect as few as 100 copies of HBV genome per milliliter of serum, and this method had superior spe-cificity for determining mixtures of wild-type and variant viruses. When sera of 40 patients were analyzed, the MALDI-TOF MS-based assay correctly identified known viral variants and additional viral quasi-species not detected by previous methods, as well as their'relative abun-dance. Conclusion The sensitivity, specificity and amenability to high-throughput analysis make MALDI-TOF MS-based assay suitable for mass screening of HBV infected patients who are receiving lamivudine.

Objective To investigate the clinical efficacy of pancreaticoduodenectomy (PD) and duodenumpreserving pancreatic head resection (DPPHR,including Beger,Frey and Berne procedures)for the treatment of chronic pancreatitis (CP) with mass in the head of the pancreas.Methods The clinical data of 48 patients with CP who were admitted to the Armed Police Corps Hospital of Hunan province(13) and the Third Xiangya Hospital of Central South University (35) between January 2007 and December 2013 were retrospectively analyzed.The operation methods were selected according to clinical symptoms,imaging findings and intraoperative pathological examinations.Twenty-three patients receiving PD (Whipple procedure or pylorus-preserving PD) were allocated into PD group and 25 receiving DPPHR (Beger,Frey and Berne procedures) were allocated into DPPHR group.The operation time,volume of intraoperative blood loss,rate of postoperative pain relief,changes of pancreatic endocrine and exocrine function,complications,duration of hospital stay and hospital expenses in the 2 groups were analyzed.Patients were followed up by telephone interview and outpatient examination up to September 2014.Measurement data with normal distribution were presented as (x) ± s.Comparison between groups was analyzed using the t test.Count data were analyzed using chi-square test or Fisher exact probability.Results Of the 23 patients in the PD group,15 patients received Whipple procedure and 8 patients received pylorus preserving PD.Of 25 patients in the DPPHR group,8 patients received Beger procedure,13 patients received Frey procedure and 4 patients received Berne procedure.The operation time and volume of intraoperative blood loss were (5.5 ± 0.4) hours,(372 ± 174) mL in the PD group,and (4.2 ± 0.6) hours,(272 ± 114) mL in the DPPHR group,showing significant differences between the 2 groups (t =8.712,2.375,P ＜ 0.05).Three patients had massive hemorrhage in the PD group and 2 patients receiving Beger procedure had massive hemorrhage due to portal vein injury,with no significant difference (x2=0.010,P ＞ 0.05).The intraoperative pathologic examinations of frozen section showed chronic inflammation in all pancreatic tissue samples with fibrous tissue proliferations.Overall pain relief rate was 95.7％ (22/23) in the PD group,including 20 complete remissions and 2 partial remissions,and overall pain relief rate was 92.0％ (23/25) in the PD group,including 18 complete remissions and 5 partial remissions,which were no different in overall pain relief rate (x2 =0.000,P ＞ 0.05).The morbidity of postoperative diabetes mellitus and dyspepsia with fatty diarrhea were 38.9％ (7/18) and 35.7％ (5/14) in the PD group,which were no different from 9.5％ (2/21) and 20.0％ (3/15) in the DPPHR group (x2=3.200,0.281,P ＞0.05).The incidence of postoperative complication was 30.4％ (7/23) in the PD group,including 1 case of intra-abdominal hemorrhage,pancreatic fistula and localized peritonitis,1 case of pancreatic fistula,2 cases of biliary fistula,3 cases of delayed gastric emptying.Patients with pancreatic fistula and biliary fistula recovered after 1-week sufficient drainage.The incidence of postoperative complication was 4.0％ (1/25) in the DPPHR group,including 1 case of pancreatic fistula,showing significant difference in incidence of postoperative complication (x2=4.274,P ＜ 0.05).The duration of postoperative stay and hospital expense were (12.4 ± 2.5) days and (57 751 ± 6 772) yuan in the PD group,which were significantly different from (8.2 ± 1.8) days and (49 109 ± 6 168)yuan in the DPPHR group (t =6.576,4.645,P ＜ 0.05).Forty-eight patients were followed up with a median time of 51.6 months (9.0-92.0 months).Of the 2 patients died,1 patient who underwent Frey procedure died 3 months after diagnosis of pancreatic cancer due to epigastric pain at postoperative month 6,the other died 2 years later due to cardiovascular disease.Among 48 patients with follow-up,1 received biliary-intestine drainage 6 months later and other patients had no recurrence or canceration.Conclusions DPPHR is safe and effective for chronic pancreatitis with mass in the head of the pancreas,having advantages such as shorter duration of operation,less intraoperative hemorrhage,faster postoperative recover,shorter duration of hospital stay and delayed hypofunction of pancreatic endocrine and exocrine function.But DPPHR cannot completely replace PD,It is necessary to master indications for all kinds of operations and choose proper operative approaches based on lesion characteristics.

Objective To analyze the clinical effect of pedicle screw fixation in the treatment of multi-segmental lumbar fracture and dislocation under the guidance of visualization technique. Methods A total of 21 patients with multi-segmental lumbar fracture and dislocation were selected from November 2012 to November 2013. Before the screw implantation, the structure of bilateral pedicle was observed through Mimics software and the implantation parameters were measured. The position of pedicle screws by postoperative CT scan, operation time, and the satisfaction of the patients were assessed. The percentages of anterior vertebral height and Cobb′s angle were measured before operation, 2 weeks and 8 months after operation. Results All patients were satisfied with informed consent score and the way of pedicle screw and the selection of plant were more reasonable. With better screw position, shorter operative time and less blood loss and adverse reactions, pedicle screw fixation achieved good effect. Conclusion With high security and considerable clinical value, pedicle screw fixation in the treatment of multi-segmental lumbar fracture and dislocation under the guidance of visualization technique has exact and good effecct.