[Establishment of the quality assessment system for pancreatic cancer surgery: from "single complication assessment" to "textbook outcome"]

With the development of neoadjuvant therapy and a multidisciplinary team, the treatment of pancreatic cancer has gradually expanded from "resection" to "cure"."Curative resection" as the core part of the integrated treatment model for patients, its quality directly determines the short-term outcome and affects the long-term prognosis. Previously, the "single complication assessment" model was used to measure the quality of pancreatic cancer surgery. However, the incidence of any specific complication cannot cover the entire surgical procedure, making it difficult to quantify and standardize the interpretation of the outcomes. Recently, the concept of textbook outcome, a comprehensive indicator, has gained popularity in surgical research. Textbook outcome includes multiple complication parameters and reflects optimal surgical outcomes in an "all or none" approach. Implementing a quality improvement program that focuses on textbook outcome will increase the overall standard of complex surgery, ultimately advancing the surgical care of pancreatic cancer in the future. In this article, the latest advances in relevant research are analyzed to provide a brief overview of the textbook outcome of pancreatic cancer.

[Pharmacokinetics and pharmacodynamics of antibiotics in septic children treated with extracorporeal membrane oxygenation]

Objective: To investigate the characteristics of pharmacokinetic (PK) and pharmacodynamic (PD) parameters of antibacterial agents in children with sepsis treated by extracorporeal membrane oxygenation (ECMO). Methods: In this prospective cohort study, 20 children with sepsis (confirmed or suspected) who were treated with ECMO and antimicrobial in the Department of Critical Medicine of Hunan Children's Hospital from March 2021 to December 2022 were enrolled as the ECMO group. Through therapeutic drug monitoring (TDM), the PK-PD parameters of antibacterial agents were analyzed. Twenty five children with sepsis in the same department who were treated with vancomycin but no ECMO at the same time were enrolled as the control group. The individual PK parameters of vancomycin were calculated by Bayesian feedback method. The PK parameters in the two groups were compared, and the correlation between trough concentration and area under the curve (AUC) was analyzed. Wilcoxon rank sum test was used for inter group comparison. Results: Twenty patients in the ECMO group, included 6 males and 14 females, with an onset age of 47 (9, 76) months. In the ECMO group, 12 children (60%) were treated with vancomycin, and the trough concentration was less than 10 mg/L in 7 cases, 10-20 mg/L in 3 cases, and >20 mg/L in 2 cases; AUC/minimum inhibitory concentration (MIC) (MIC=1 mg/L)<400 was in 1 case, 400-600 in 3 cases, and >600 in 8 cases. Among the 11 children (55%) who were treated with β-lactam antibiotics, there were 10 cases with drug concentration at 50% dosing interval (C_T50)>4 MIC and 9 cases with trough concentration>MIC, both C_T50 and trough concentration of cefoperazone reached the target. Among the 25 cases of control group, 16 were males and 9 females, with an onset age of 12 (8, 32) months. There was a positive correlation between vancomycin trough concentration and AUC (r²=0.36, P<0.001). The half-life of vancomycin and the 24-hour AUC (AUC_{0-24 h}) in the ECMO group were higher than those in the control group (5.3 (3.6, 6.8) vs. 1.9 (1.5, 2.9) h, and 685 (505, 1 227) vs. 261 (210, 355) mg·h/L, Z=2.99, 3.50, respectively; both P<0.05), and the elimination rate constant and clearance rate was lower than those in the control group (0.1 (0.1, 0.2) vs. 0.4 (0.2, 0.5), 0.7 (0.5, 1.3) vs. 2.0 (1.1, 2.8) L/h, Z=2.99, 2.11, respectively; both P<0.05). Conclusion: The PK-PD parameters in septic children treated by ECMO varied with a longer half-life, higher AUC_{0-24 h}, lower elimination rate constant and clearance rate.

[Quality assessment indictors and benchmarks for pancreatic surgery]

Pancreatic surgery is the most complex type of abdominal surgery,with high technical requirements and long learning curve,and the quality of surgery is directly related to the prognosis of the patients. In recent years,more and more indicators have been used to evaluate the quality of pancreatic surgery,such as operation time,intraoperative blood loss,morbidity,mortality, prognosis and so on,and different evaluation systems have been established,including benchmarking,auditing,outcome evaluation based on risk factor adjustment and textbook outcomes. Among them,the benchmark is the most widely used to evaluate surgical quality and is expected to become the standard for comparison among peers. This article reviews existing quality evaluation indicators and benchmarks for pancreatic surgery and anticipates its future application prospects.

[Diagnosis and treatment of blunt high-grade pancreatic trauma]

The clinical data of 20 patients with blunt high-grade pancreatic trauma who were admitted to the Department of Hepatobiliary and Pancreatic Surgery of Changhai Hospital Affiliated to Naval Military Medical University from December 2003 to February 2022 were retrospectively analyzed. There were 15 males and 5 females with a median age of 39 years (range: 14-54 years). The degree of pancreatic injury was graded according to the American Association for the Surgery of Trauma (AAST) scale, including 10 cases of grade Ⅲ (50%), 8 cases of grade Ⅳ (40%), and 2 cases of grade Ⅴ (10%). Then, the strategy of diagnosis and treatment for blunt high-grade pancreatic trauma was summarized. The diagnostic rate of CT was 78.9%. Finally, 17 cases (85%) were cured and 3 cases (15%) died. Among the 10 patients with grade Ⅲ pancreatic injury, 7 cases received distal pancreatectomy and splenectomy, 1 case received distal pancreatectomy with spleen preserved, 1 case received pancreatic duct stent placement under endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous catheter drainage (PCD), and 1 case received only PCD. Among 8 cases of grade Ⅳ, 3 cases underwent Roux-en-Y pancreaticojejunostomy, 1 case received distal pancreatectomy and splenectomy, 1 case underwent distal pancreatectomy with spleen preserved, 2 cases received necrotic tissue removal+external drainage of pancreatic duct+abdominal drainage, and 1 case received exploratory laparotomy and gauze packing hemostasis. For 2 cases of grade Ⅴ, 1 underwent pylorus preserving pancreaticoduodenectomy, and the other case underwent pancreaticoduodenectomy combined with right hemicolectomy and splenectomy. Therefore, the treatment of blunt high-grade pancreatic trauma should follow the individualized treatment strategy, pay attention to the control of bleeding, extensive external drainage, appropriate debridement and resection and rational application of damage control surgery, select appropriate patients for conservative treatment, and ultimately benefit the patient.

[Clinical effect of endoscopic transnasal sphenoidal approach with simple muscle packing for intrasellar arachnoid cyst]

Objective: To examine the clinical effect of simple muscle packing through transnasal sphenoid approach in the treatment of intrasellar arachnoid cyst. Methods: The clinical data of 11 patients with intrasellar arachnoid cyst treated by transnasal sphenoidal approach with simple muscle packing at the Neurosurgery Department of the First Affiliated Hospital of Zhengzhou University from January 2014 to February 2020 were retrospectively analyzed. There were 5 males and 6 females, with a median age of 48 years (range: 23 to 75 years). The clinical manifestations included headache in 6 cases, dizziness in 4 cases, hypo-libido in 1 case, disturbance of consciousness in 1 case, visual impairment in 7 cases and mixed pituitary dysfunction in 5 cases. The enlargement of the sellar fossa was seen in the preoperative MRI images. The enhanced MRI images showed that the cyst wall of the intrasellar arachnoid cyst was not enhanced, and the compression and thinning of the sellar base was seen in the CT images. In 9 cases, the cyst extended suprasellar and the sellar septum was "arched". In 7 cases, the cyst compressed the optic chiasm upward. The cyst walls of all patients were incised through the nasal sphenoid approach under the endoscope, and the muscle was packed after sufficient drainage. The postoperative symptoms, pituitary endocrine function and recurrence of patients were followed up. Results: MRI images of the sellar region in all patients showed significant reduction or disappearance of cysts. Intracranial infection occurred in 1 case and electrolyte disorder in 2 cases, which were relieved after symptomatic treatment. No cerebrospinal fluid rhinorrhea occurred. Postoperative clinical symptoms were completely relieved in 6 cases and partially relieved in 5 cases. Pituitary endocrine function recovered completely in 2 cases and improved significantly in 4 cases. All patients were followed up for 10 to 40 months. One patient found to have a partial recurrence of the cyst 3 months after surgery. Because there were no new symptoms appeared, the follow-up was continued without second operation. Conclusion: Transnasal sphenoidal approach is a feasible method for the treatment of intrasellar arachnoid cyst.

Artemisia ordosica Polysaccharide Alleviated Lipopolysaccharide-induced Oxidative Stress of Broilers via Nrf2/Keap1 and TLR4/NF-κB Pathway

Artemisia ordosica is one of the main shrubby perennials belonging to Artemisia species of Asteraceae and could be used in folk Chinese/Mongolian medicine to treat symptoms of various inflammatory ailments. The present study was conducted to investigate the protective effects of dietary Artemisia ordosica polysaccharide (AOP) against lipopolysaccharide (LPS) induced oxidative stress in broilers via Nrf2/Keap1 and TLR4/NF-κB pathway. A total of 192 1-day-old Arbor Acres male broilers were randomly allotted to four treatments with 6 replicates (n = 8): (1) CON group, non-challenged broilers fed basal diet; (2) LPS group, LPS-challenged broilers fed basal diet; (3) AOP group, non-challenged broilers fed basal diet supplemented with 750 mg/kg AOP; (4) LPS+AOP group, LPS-challenged broilers fed basal diet supplemented with 750 mg/kg AOP. The trial included starter phase (d 1-14), stress period Ⅰ (d 15-21), convalescence Ⅰ (d 22-28), stress period Ⅱ (d 29-35) and convalescence Ⅱ (d 36-42). During stress period Ⅰ (on d 15, 17, 19 and 21) and stress period Ⅱ (on d 29, 31, 33 and 35), broilers were injected intra-abdominally either with LPS solution or with an equal amount of sterile saline. The results showed that dietary AOP supplementation alleviated LPS-induced reduction in antioxidant enzyme activity and excessive production of ROS, 8-OHdG and PC in serum of broilers challenged with LPS. Moreover, dietary AOP supplementation alleviated the decrease of T-AOC and activities of SOD, CAT and GPx in liver of broilers challenged with LPS by increasing expression of Nrf2, and inhibiting over-expression of Keap1 both at gene and protein level. Additionally, dietary AOP supplementation decreased the over-production of IL-1β and IL-6 in liver of broilers challenged by LPS through decreasing mRNA expression of TLR4, MyD88, NF-κB P65, IL-1β and IL-6, and alleviating the increase of protein expression of TLR4, IKKβ, NF-κB P65, IL-1β, IL-6, and the decrease of protein expression of IkBα. In conclusion, dietary AOP supplementation could alleviate LPS-induced oxidative stress through Nrf2/Keap1 and TLR4/NF-κB pathway.

[Diagnostic efficacy for predicting intraductal papillary mucinous neoplasms of the pancreas with high grade dysplasia or invasive carcinoma based on the surgery indications in different guidelines]

Objective: To evaluate the performance of the European Evidence-based Guidelines on Pancreatic Cystic Neoplasms (EEGPCN)(2018) and International Association of Pancreatology(IAP) Guideline(Version 2017) in predicting high grade dysplasia/invasive carcinoma-intraductal papillary mucinous neoplasm(HGD/INV-IPMN). Methods: A retrospective analysis of 363 patients,who underwent surgical resection in Changhai Hospital affiliated to Navy Medical University from January 2012 to December 2018 and were pathologically identified as (intraductal papillary mucinous neoplasm, IPMN),was performed. The patients,including 230 males and 133 females,aging (61.7±10.1) years(range:19 to 83 years). The proportion of HGD/INV-IPMN who met with the absolute indication(AI) of EEGPCN and high risk stigma(HRS) of IAP were compared. The binary Logistic regression analysis was used to find the independent risk factors of HGD/INV-IPMN.Eight combinations of risk factors derived from relative indication/worrisome feature or risk factors in this study,were made to evaluate the diagnostic efficacy. The area under curve(AUC) of receiver operating characteristics was used to evaluate the the cutoff value of risk factors(①CA19-9≥37 U/ml,②diameter of main pancreatic duct 5.0-9.9 mm,③enhancing mural nodule<5 mm,④(acute) pancreatiti,⑤^acyst diameter ≥40 mm,⑤^bcyst diameter ≥30 mm, ⑥thickened or enhancing cyst walls,⑦neutrophile granulocyte to lymphocyte ratio(NLR)≥2, ⑧cyst located in head, uncinate or neck,⑨carcinoembryonic antigen(CEA) ≥5 μg/L) number for predicting HGD/INV-IPMN.The accuracy,sensitivity,specificity,positive predictive value,negative predictive value,true positive,true negative,false positive,false negative,positive likelihood ratio,negative likelihood ratio,Youden index and F1 score were calculated. Results: Ninety-two patients(49.5%) of 186 ones who met AI and 85 patients(48.3%) of 176 ones who met HRS were respectively confirmed as HGD/INV-IPMN. In those patients who were not met AI,tumor location,thickened/enhancing cyst wall,CA19-9 elevated,NLR≥2 and CEA elevated were significantly (P<0.05) correlated with HGD/INV-IPMN. And tumor location(head/uncinate/neck vs. body/tail,OR=3.284,95%CI:1.268-8.503,P=0.014),thickened/enhancement cyst wall (with vs.without,OR=2.713,95%CI:1.177-6.252,P=0.019),CA19-9(≥37 U/L vs.<37 U/L, OR=5.086,95%CI:2.05-12.62,P<0.01) and NLR(≥2 vs.<2,OR=2.380,95%CI:1.043-5.434,P=0.039) were the independent risk factors of HGD/INV-IPMN. Patients with ≥4 risk factors of 9 in combination Ⅷ(①②③④⑤^b⑥⑦⑧⑨) were diagnosed as HGD/INV-IPMN with the moderate accuracy(71.0%),moderate sensitivity (62.0%) and moderate specificity (73.0%). Patients with ≥4 risk factors of 9 in Combination Ⅶ(①②③④⑤^a⑥⑦⑧⑨) were diagnosed as HGD/INV-IPMN with the highest specificity(83.0%) and patients with ≥3 risk factors of 8 in combination Ⅵ(①②③④⑤^b⑥⑧⑨) were diagnosed as HGD/INV-IPMN with the highest sensitivity(74.0%). The AUC for diagnosis of HGD/INV-IPMN in combination Ⅵ,Ⅶ and Ⅷ were 0.72,0.75 and 0.75,respectively. Older patients and younger patients could respectively refer to combination Ⅶ and combination Ⅵ to improve the management of IPMN. Conclusions: Patients who meet AI of EEGPCN should undertake resection, otherwise the method we explored is recommended. The method of improvement for diagnosis of HGD/INV-IPMN is relatively applicable and efficient for decision-making of surgery, especially for younger patients with decreasing of missed diagnosis and elder patients with decreasing of misdiagnosis.

[Verification of clinical applicability of the non-special perioperative administration for enhanced recovery after surgery of gastric cancer patients: a Chinese single-center observational report]

Objective: To verify clinical applicability of the non-special perioperative administration for enhanced recovery after surgery (ERAS) proposed by Japanese scholars in Chinese gastric cancer patients. Methods: The main measures of the non-special perioperative administration for ERAS are as follows: (1) discussion of multiple disciplinary team before surgery; (2) rehabilitation education for patients; (3) no routine bowel preparation before surgery; (4) placement of nasogastric tube for decompression routinely before operation and removal as early as 24 hours after surgery; (5) appropriate rehydration; (6) antibiotic prophylaxis before surgery; (7) place abdominal drainage tubes when necessary; (8) epidural patient-controlled analgesia and oral medication for postoperative pain management; (9) start low-molecular-weight heparin injection 48h after surgery and ambulation every day to prevent deep vein thrombosis; (10) postoperative dietary management and supplement with parenteral nutrition intermittently; (11) remove Foley catheter about 24 hours after surgery. A retrospective cohort study was performed, including 203 patients undergoing radical gastrectomy at Department of Gastroenterology, Tianjin Medical University Cancer Institute and Hospital from January 2017 to December 2018. Inclusion criteria were patients who were ≤75 years old without distant metastasis by preoperative examination, were diagnosed as gastric adenocarcinoma by postoperative histopathology and had complete clinicopathological and follow-up data. Patients with history of other malignancies and gastrectomy, extensive implantation of the abdominal cavity or malignant ascites by intraoperative exploration, death within 1 month after surgery, and residual gastric cancer were excluded. The perioperative management methods were chosen by patients. There were 123 patients who followed non-special perioperative administration for ERAS (non-special preparation group) and 80 patients who underwent traditional perioperative management (traditional method group). The primary outcomes (postoperative hospital stay, time to the first flatus, time to the first fluid diet, time to the first ambulatory activity, morbidity of postoperative complication, mortality, and readmission rate) and secondary outcomes (operative time, intraoperative blood loss and postoperative pain score) were compared between the two groups. Results: Compared to the traditional method group, the non-special preparation group had shorter time to the first flatus [(3.6±1.1) days vs. (4.8±1.4) days, t=3.134, P=0.003], shorter time to the first liquid diet [(2.6±0.9) days vs. (5.5±1.6) days, t=15.105, P<0.001], shorter time to the first ambulatory activity [(1.9±0.5) days vs. (4.1±1.1) days, t=8.543, P<0.001] and shorter postoperative hospital stay [(9.6±2.3) days vs. (12.9±2.3) days, t=5.020, P<0.001]. Besides, incidences of pancreatic leakage [6.5% (8/123) vs. 16.3% (13/80), χ(2)=4.964, P=0.026], lymphatic leakage [1.6% (2/123) vs. 13.8% (11/80), χ(2)=11.887, P=0.001], peritoneal effusion [2.4% (3/123) vs. 10.0% (8/80), χ(2)=4.032, P=0.045], and gastroparesis [0.8% (1/123) vs. 7.5% (6/80), χ(2)=4.657, P=0.031] in the non-special preparation group were significantly lower. The overall morbidity of postoperative complications and incidences of pulmonary infection and intestinal adhesion were not significantly different between the two groups (all P>0.05). As for the secondary outcomes, compared to the traditional method group, the non-special preparation group had less intraoperative blood loss [(80.4±24.4) ml vs. (100.5±19.4) ml, t=3.134, P=0.003] and lower postoperative pain score [postoperative day 1: (4.4±0.3) vs. (5.3±0.8), t=2.504, P=0.037],while the difference in operative time was not significant (P>0.05). Conclusion: The non-special perioperative administration for ERAS proposed by Japanese scholars is effective and safe, which has certain clinical applicability and value for Chinese patients with gastric cancer.

Diffusion MRI Derived per Area Vessel Density as a Surrogate Biomarker for Detecting Viral Hepatitis B-Induced Liver Fibrosis: A Proof-of-Concept Study

Liver vessel density can be evaluated by an imaging biomarker diffusion-derived vessel density (DDVD): DDVD/area(b0b2) = Sb0/ROIarea0 - Sb2/ROIarea2, where Sb0 and Sb2 refer to the liver signal when b is 0 or 2 (s/mm²); ROIarea0 and ROIarea2 refer to the region of interest (ROI) on b = 0 or 2 images; and Sb2 may be replaced by Sb15 (b = 15). This concept was validated in this study. Liver diffusion images were acquired at 1.5 T. For a scan-rescan repeatability study of six subjects, b values of 0 and 2 were used. The validation study was composed of 26 healthy volunteers and 19 consecutive suspected chronic viral hepatitis B patients, and diffusion images with b values of 0, 2, 15, 20, 30, 45, 50, 60, 80, 100, 200, 300, 600, and 800 were acquired. Four patients did not have liver fibrosis, and the rest were four stage 1, three stage 2, four stage 3, and one stage 4 patients, respectively. The intraclass correlation coefficient for repeatability was 0.994 for DDVD/area(Sb0Sb2) and 0.978 for DDVD/area(Sb0Sb15). In the validation study, DDVD/area(Sb0Sb2) and area(Sb0Sb15) were 14.80 ± 3.06 and 26.58 ± 3.97 for healthy volunteers, 10.51 ± 1.51 and 20.15 ± 2.21 for stage 1-2 fibrosis patients, and 9.42 ± 0.87 and 19.42 ± 1.89 for stage 3-4 fibrosis patients. For 16 patients where IVIM analysis was performed, a combination of DDVD/area, PF, and Dfast achieved the best differentiation for nonfibrotic livers and fibrotic livers. DDVD/area were weakly correlated with PF or Dfast. Both DDVD/area(Sb0Sb2) and area(Sb0Sb15) are useful imaging biomarkers to separate fibrotic and nonfibrotic livers, with fibrotic livers having lower measurements.

[Analysis of prognostic factors for hyperamylasemia following pancreaticoduodenectomy]

Objective: To investigate the prognostic factors of hyperamylasemia following pancreaticoduodenectomy (PD) . Methods: Clinical data of 359 patients were collected prospectively who underwent PD by the same group at Changhai Hospital of Navy Medical University from January 2017 to June 2018.There were 212 males and 147 females.The median age was 63 years old (range: 23 to 82 years old) .According to whether the patient's serum amylase was greater than 120 U/L at 0 or 1 day after surgery,the patients were divided into hyperamylasemia group and non-hyperamylasemia group. Univariate analysis and multivariate analysis were used to find out the prognostic factors of hyperamylasemia after PD. Results: Of the 359 patients, 238 cases (66.3%) developed hyperamylasemia.The incidence rate of clinically related pancreatic fistula (15.1% vs.2.5%, P<0.01) , grade B/C post pancreatectomy hemorrhage (8.8% vs. 2.5%, P<0.01) , and surgical site infection (9.2% vs. 3.3%, P=0.04) was significantly higher in the hyperamylasemia group.The severity of complications (CD grade≥Ⅲ: 11.3% vs.4.1%, P=0.023) and postoperative hospital stay (11 days vs. 9 days, P=0.001) were higher in the hyperamylasemia group.In the multivariate analysis, the main pancreatic duct diameter (MPD) ≤3 mm (OR=4.469, 95% CI: 2.563-7.793, P<0.01) , pathological type of disease (pancreatic cancer or pancreatitis) (OR=0.230, 95% CI: 0.122-0.436, P<0.01) and soft texture of pancreas (OR=3.297, 95%CI: 1.930-5.635, P<0.01) were independent prognostic factors for hyperamylasemia. Conclusions: Post-PD hyperamylasemia increased the incidence and severity of postoperative complications after PD.MPD≤3 mm, soft texture of pancreas and pathological type of disease were independent prognostic factors of hyperamylasemia.

High performance of intravoxel incoherent motion diffusion MRI in detecting viral hepatitis-b induced liver fibrosis

BACKGROUND

Recently a small cohort study demonstrated that intravoxel incoherent motion (IVIM) diffusion MRI can detect early stage liver fibrosis. Using modified IVIM data acquisition parameters, the current study aims to confirm this finding.

METHODS

Twenty-six healthy volunteers, three patients of chronic viral hepatitis-b but without fibrosis and one mild liver steatosis subject, and 12 viral hepatitis-b patients with fibrosis (stage 1-2=7, stage 3-4=5) were included in this study. With a 1.5-T MR scanner and respiration-gating, IVIM diffusion imaging was acquired using a single-shot echo-planar sequence with a b-value series of 2, 0, 1, 15, 20, 30, 45, 50, 60, 80, 100, 200, 300, 600, 800 s/mm2. Signal measurement was performed on right liver parenchyma. The first three very low b-values were excluded to improve the curve fitting stability, and bi-exponential segmented fitting was performed using the 12 b-values of 15~800 s/mm2. Both threshold b-values of 60 s/mm2 and 200 s/mm2 were tested. With a 3-dimensional tool, Dslow (D), PF (f) and Dfast (D*) values were placed along the x-axis, y-axis, and z-axis, and a plane was defined to separate healthy volunteers from liver fibrosis patients.

RESULTS

Threshold b-value of 60 s/mm2 was preferred over 200 s/mm2 for separating healthy volunteers and liver fibrosis patients. The IVIM measures of the four patients without fibrosis resembled those of healthy volunteers. When threshold b-value =60 s/mm2 was applied, PF (PF <6.49%) could differentiate healthy livers and all fibrotic livers with 100% sensitivity and specificity. For the patients' measurement, PF and Dfast were highly correlated with a Pearson correlation coefficient r of 0.865 (P<0.001); while the correlations between slow diffusion compartment (Dslow) and fast diffusion compartment (Dfast or PF) were not statistically significant.

CONCLUSIONS

This study confirms previous report that IVIM diffusion MRI has high diagnostic performance in detecting viral hepatitis-b induced liver fibrosis.

[Progress in clinical research of pancreatic cancer: from "resection" to "cure"]

Because of the high malignancy of pancreatic ductal adenocarcinoma, the cancer-related mortality of pancreatic ductal adenocarcinoma is increasing year by year. Despite advance in surgical techniques, the 5-year survival rate of patients after resection is still less than 30%. Recent studies have found that pancreatic ductal adenocarcinoma is a systemic disease, which may not be cured completely by up-front resection, but requires perioperative multidisciplinary therapy. With the concept of "potentially curable pancreatic cancer" , clinicians need to evaluate the resectability of pancreatic ductal adenocarcinoma accurately before operation, and use the innovative multidisciplinary therapy including neoadjuvant chemoradiotherapy,surgery and adjuvant chemoradiotherapy to improve the R0 resection rate and reduce the risk of early metastasis. Therefore, the therapeutic goal of pancreatic ductal adenocarcinoma is no longer "simple resection" , but long survival through perioperative multidisciplinary treatment. In this article, we briefly introduce the progress of resectability assessment, surgical techniques and perioperative adjuvant therapy of "potentially curable pancreatic cancer" .

[Analysis on the clinical therapeutic effects of arterial first approach pancreatoduodenectomy in the treatment of borderline resectable pancreatic adenocarcinoma]

Objective: To compare the clinical therapeutic effects of arterial first approach pancreaticoduodenectomy(AFA-PD) with standard approach pancreaticoduodenectomy(SPD) in the treatment of borderline resectable pancreatic cancer (BRPC). Methods: A retrospective analysis of the clinical data of 113 cases of pancreatic cancer patients from January 2014 to August 2015 at Department of Hepato-Biliary-Pancreatic Surgery, Changhai Hospital, the Second Military Medical University, including 43 cases in AFA-PD group and 70 cases in SPD group.Every patient had gone high-resolusion computed tomography before the surgery, when BRPC was definitely diagnosed by both experienced radiologist and pancreatic surgeon.There were 24 males and 19 females in the AFA-PD group, with average age of (61.6±10.2)years.And in the SPD group, there were 47 males and 23 females, with average age of (62.7±9.4)years. Results: The operation time was (210.7±31.5)minutes in AFA-PD group, (187.9±27.4)minutes in SPD group, and peroperative bleeding volume was (1 007.1±566.3)ml in AFA-PD group, (700.0±390.0)ml in the other group.Those two indicators of AFA-PD group, compared with SPD group, were relatively higher, the difference was statistically significant(all P<0.01). And with regard to postoperative diarrhea(9.3% vs.5.7%), postoperative 1, 3 days of white blood cells(postoperative 1 day: (13.3±1.1)×10(9)/L vs.(12.4±2.4)×10(9)/L; postoperative 3 days: (12.7±1.6)×10(9)/L vs.(11.7±2.5)×10(9)/L), postoperative 1, 3, 5 days of peritoneal drainage fluid volume(postoperative 1 day: (184±42)ml vs.(156±54)ml; postoperative 3 days: (155±48)ml vs.(133±35)ml; postoperative 5 days: (66±20)ml vs.(47±31)ml), the differences between the two groups were statistically significant (all P<0.05). One patient in the SPD group was treated with unplanned secondary surgery for postoperative intraperitoneal hemorrhage, and the patient was cured and discharged.There was no death in the two groups within 30 days after surgical operation and no patient with positive gastric margin, duodenal margin, or anterior margin.The resection rate of superiormesenteric artery(SMA) margin R0 in AFA-PD group was higher than that in SPD group (P=0.019). The two groups were followed up for 14 to 30 months.As for AFA-PD group, the average survival time, progression free survival time and median survival time was respectively (20.4±1.2)months, (21.5±1.4)months and 20 months.There were 3 cases(7.0%) with local recurrence and 8 cases(18.6%) with liver metastasis or distant metastasis.In the SPD group, the average survival time, progression free survival time and median survival time was (17.1±1.1)months, (16.4±1.3)months and 16 months, respectively.There were 13 cases(18.6%) with local recurrence and 25 cases(35.7%) with liver metastasis or distant metastasis.As a result, the AFA-PD group had longer survival time(P=0.001)and progression free survival time(P=0.002). However, the lower local recurrence and distant metastasis rate in AFA-PD group did not reach statistical standard (P>0.05). Conclusion: The arterial first approach pancreaticoduodenectomy is safe and effective in the treatment of borderline resectable pancreatic cancer, which can improve the resection rate of SMA margin R0, and prolong patient survival time.

[A survey of mental health status in armored vehicle crew]

OBJECTIVE

To investigate the mental health status in armored vehicle crew (commanders, gunners, and drivers) , to know the level of mental health in them, and to provide educational intervention.

METHODS

In April 2009, 120 male armored vehicle crew with >2 driving years were enrolled as battle group, and 70 male persons within the same age group who were not engaged in armored vehicle operation were enrolled as control group. The Symptom Checklist-90 (SCL-90) was used to evaluate the mental status of the 180 subjects.

RESULTS

Compared with the control group, the battle group showed significantly higher scores on the subscales of obsessive-compulsive symptom, interpersonal sensitivity, depression, anxiety, phobic anxiety, and paranoid ideation (t=2.323, 3.250, 3.158, 2.712, 2.391, and 2.137, all P<0.05) , as well as significantly higher total score, number of positive items, and average score of positive symptoms (t=4.128, 4.357, and 4.632, all P<0.05). In the battle group, the scores on the subscales of somatization, obsessive-compulsive symptom, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, psychoticism, and additional items, total score, number of positive items, and average score of positive symptoms were significantly lower than the military reference values (t=4.364, 5.127, 5.280, 3.783, 7.012, 5.361, 4.369, 6.167, 6.476, 3.558, 6.357, 4.379, and 6.763, all P<0.05).

CONCLUSION

A survey should be performed on the mental health status of armored vehicle crew, including obsessive-compulsive symptom, interpersonal sensitivity, depression, and anxiety. Mental health service for the crew should be enhanced to improve their psychological quality.

Process of Bipolaris sorghicola invasion of host cells

Target leaf spot is a sorghum leaf disease caused by Bipolaris sorghicola, a species of fungus with a global distribution. In this study, we investigated the process by which B. sorghicola invades cells of barley, onion, Arabidopsis thaliana species, and sorghum. The results showed that within 8 h of coming into contact with host cells, the hyphal ends of B. sorghicola expand and form a uniform infective penetration pegbolt-like structure; a primary infection mycelium can be formed inside host cells within 24 h after contact, which can infect closed cells after 48 h. A mycelium can grow within the gap between cells and form infective hyphae. The pathogen infection process was the same in different host cells. B. sorghicola can affect root cells through soil infection, indicating that it may also have characteristics of soil-borne pathogens.

Morphology and photosynthetic enzyme activity of maize phosphoenolpyruvate carboxylase transgenic rice

The morphology and photosynthetic enzyme activity were studied in maize phosphoenolpyruvate carboxylase transgenic rice and non-transgenic rice. The results showed that compared with non-transgenic rice, phosphoenolpyruvate carboxylase transgenic rice was taller and had a stronger stalk, wider leaves, and more exuberant root system, with increased photosynthetic enzyme activity and improved yield components. Therefore, given the superiority of this plant type and heterosis, this is a novel breeding strategy for rice for the introduction of C4 photosynthesis genes into high-yielding rice.

Construction of recombinant lentivirus vector for tumor vasoinhibitory peptide alphastatin gene delivery

Angiogenesis is a prerequisite for tumor progression and metastasis. Alphastatin, as an endogenous angiogenesis inhibitor, was recently used as an anticancer agent in several tumor models. We constructed recombinant self-inactivating lentivirus vectors expressing alphastatin and evaluated their ability to transfer genes into human umbilical vein endothelial cells (HUVECs) as well as their antiangiogenic activities in vitro. Recombinant self-inactivating lentiviral vectors efficiently and stably transduced endothelial cells, and lentivirus-transduced HUVECs were capable of sustainedly secreting the antiangiogenesis peptide alphastatin. Long-term expression and secretion of alphastatin resulted in significant inhibition of endothelial cell angiogenesis induced by vascular endothelial growth factor. This report presents the first use of lentivirus-based vectors to deliver the endogenous angiogenesis inhibitor alphastatin, and suggests the potential utility of antiangiogenic gene therapy with lentiviral vectors for the treatment of cancer.

Altered expression of HOXA10 in endometriosis: potential role in decidualization

Endometriosis is a poorly understood gynaecologic disorder that is associated with infertility. In this study, we examined the expression of HOXA10 in the eutopic endometrium of baboons with induced endometriosis. A decrease in HOXA10 mRNA was observed after 3, 6, 12 and 16 months of disease, which reached statistical significance at 12 and 16 months. HOXA10 protein levels were decreased in both the epithelial and stromal cells of the endometrium. Furthermore, expression of beta3 integrin (ITGB3), which is upregulated by HOXA10, was decreased, whereas EMX2, a gene that is inhibited by HOXA10, was increased. Next, methylation patterns of the HOXA10 gene were analysed in the diseased and control animals. The F1 region on the promoter was found to be the most significantly methylated in the endometriosis animals and this may account for the decrease in HOXA10 expression. Finally, we demonstrate that stromal cells from the eutopic endometrium of baboons with endometriosis expressed significantly higher levels of insulin-like growth factor binding protein-1 (IGFBP1) mRNA than disease-free animals in response to estradiol, medroxyprogesterone acetate and dibutyryl cAMP (H + dbcAMP). The functional role of HOXA10 in IGFBP1 expression was further explored using human endometrial stromal cells (HSC). Overexpression of HOXA10 in HSC resulted in a decrease of IGFBP1 mRNA, whereas silencing HOXA10 caused an increase of IGFBP1 mRNA, even in the presence of H + dbcAMP. These data demonstrate that HOXA10 negatively influences IGFBP1 expression in decidualizing cells. Thus, the decrease in HOXA10 levels may in part be involved with the altered uterine environment associated with endometriosis.

[Synergistic effects by P and N pollution to fluctuation behavior/bloom of algae along the Three-Gorges valley]

Absorption rate coefficient of algae omega(i) to nutrients such as N and P could be used for describing algal increases/decreases velocity in water areas in theory. omega(i) raise might correspond to algal quickly growth and to ccelerate absorption of N and P while omega(i) decrease might correspond to algal decompose and release of N and P. According to locale measuring data along the Three-Gorges valley and algal dynamics model of nutritious absorption we have obtained some interest 3-dimension figures in which omega(i) will varies up and down obviously with N and P concentration in special bound to show a synergistic effects of N and P that might reveal an inner behavior of algal bloom/decompose. The research results explain in reason: (1) algal blooms do will happen in one special P/N range in a certain water system; (2) when omega(1) and omega(2) ascend rapidly and simultaneously in positive direction at same time algae would bloom, and when omega(1) and omega(2) descend sharply and simultaneously in negative direction at same time algae would decompose; (3) The velocity of algal bloom is not only same approximately as one of algal decompose, but also its variety has evidently periodic fluctuation. All of these could reveal effectively mechanism of nutritious absorption/release as algal bloom/decompose.

Quantitative quality control in microarray image processing and data acquisition

A new integrated image analysis package with quantitative quality control schemes is described for cDNA microarray technology. The package employs an iterative algorithm that utilizes both intensity characteristics and spatial information of the spots on a microarray image for signal-background segmentation and defines five quality scores for each spot to record irregularities in spot intensity, size and background noise levels. A composite score q(com) is defined based on these individual scores to give an overall assessment of spot quality. Using q(com) we demonstrate that the inherent variability in intensity ratio measurements is closely correlated with spot quality, namely spots with higher quality give less variable measurements and vice versa. In addition, gauging data by q(com) can improve data reliability dramatically and efficiently. We further show that the variability in ratio measurements drops exponentially with increasing q(com) and, for the majority of spots at the high quality end, this improvement is mainly due to an improvement in correlation between the two dyes. Based on these studies, we discuss the potential of quantitative quality control for microarray data and the possibility of filtering and normalizing microarray data using a quality metrics-dependent scheme.

Does higher concordance in monozygotic twins than in dizygotic twins suggest a genetic component?

It is widely regarded that twins can be used as a natural experiment to subject hypotheses to empirical testing regarding the contributions of genetic factors to phenotypic variability in human traits, especially behavioral traits. In genetic epidemiology, a higher concordance rate in monozygotic (MZ) twins than in dizygotic (DZ) twins is often taken as prima facie evidence for a genetic component. While twins studies have been used to estimate the contributions of genetic factors to phenotypic variability in human traits, the corresponding methodology that allows the estimation entails several crucial assumptions. The most critical is that MZ and DZ twins are equally similar environmentally. Although MZ twins are genetically more similar than DZ twins, they are often environmentally more similar. This paper demonstrates that, even in the complete absence of any genetic factor and of any biases, the greater environmental similarity alone in MZ twins can result in higher concordance rate in MZ twins than in DZ twins. This is especially true when there are multiple environmental factors, which may have multiple exposure levels and/or interact strongly, although each of them may be of low risk. This may serve as a sobering antidote to the uncritical reliance on twin studies without examining the validity of the underlying assumptions.

Gene-environment interactions and the affected-sib-pair designs

In genetic mapping of complex traits, the affected-sib-pair method (ASP) and the transmission disequilibrium test (TDT) are two methods of choice. The major appeal of both ASP and TDT is that they do not require the knowledge of mode of inheritance underlying the trait in question. The relative ease and economy for data collection also is the reason for their popularity. The basic idea of the ASP is to identify genes or chromosomal regions through identifying genetic similarity based on phenotypical similarity. TDT, on the other hand, detects susceptibility genes through detecting unusual transmission patterns in families. Since phenotypic similarity can also be caused by environmental similarity, we investigate how the presence of gene-environment interaction (GEI) affects the power of both methods. For a simple one-locus-one-risk-factor model, our results indicate that, in the presence of GEI, methods developed based on marginal penetrance functions (i.e. ignoring the risk factor) can give spurious results. The triangular restriction on allele-sharing probability may no longer be valid. If the environment effect is strong, using exposure-discordant affected sib pairs may have advantage over other designs. Above all, a genetic model involving both genetic and environmental factors behaves differently from a single-locus genetic model.

Gene-environment interaction and the mapping of complex traits: some statistical models and their implications

The manifestation of many complex diseases or traits is very likely the result of an inextricable interplay of the biological and the environmental. Yet the role of environmental effect has traditionally been played down, for various reasons. In this paper, some simple statistical models that incorporate gene-environment interaction (GEI) have been proposed and their behavior and implications investigated. These implications concern the conditional independence assumption in likelihood calculation of pedigree data, the fine-tuning of the sib pair method for mapping quantitative traits, apportioning of disease or trait variation due to specific causes. In addition, they concern properties of gene mapping methods that do not take GEI into account, and they bring into question the utility of commonly used measures of genetic effects such as recurrence risk ratio for relative pairs, twin concordance rates, and heritability coefficients. In the presence of GEI, all these measures are functions not only of genetic effects and gene frequency, but also of environmental effects, the distribution of environmental factors in the population, and of GEI. Above all, these measures are all measures of familial aggregation, since they can be significant even in the absence of any genetic component of the disease. Thus their use as indicators of the genetic basis of complex diseases is cast into doubt.

Discovery of cancer susceptibility genes: study designs, analytic approaches, and trends in technology

Determining the genetic causes of cancers has immense public health benefits, ranging from prevention to earlier detection and treatment of disease. Although a number of cancer susceptibility genes have been successfully identified, design and analytic issues remain that challenge the current paradigm of gene discovery. Some examples are the definition and measurement of cancer phenotype, the use of intermediate end points, the choice of sample (e.g., affected relative pairs versus large extended pedigrees), the choice of analytic method [e.g., parametric logarithm of the odds (LOD) score method versus model-free methods], and the influence of gene-environment interaction on linkage analysis. Furthermore, association methods, based on either the traditional case-control study design or family-based controls, are popular choices to evaluate candidate genes or screen for linkage disequilibrium. Finally, the study design and analytic methods for gene discovery are determined to some extent by what genomic technology is feasible within the laboratory. Many of the main issues related to gene discovery, as well as trends in genomic technology that will impact on gene discovery, are discussed from the perspective of their strengths and weaknesses, pointing to areas in need of further work.

Modeling the maternal-age dependency of reproductive failure and genetic fitness

The offspring of older parents are at a higher risk of suffering low birth weights and congenital birth defects that result from mutations and chromosomal anomalies. When the defect is paternal in origin, it often can be shown that the primary lesion arose during mitotic proliferation of the spermatogonial germ cell population. By contrast, germline mosaicism is seldom invoked to explain the age dependency of maternally derived aberrations because germline proliferation in the ovary is already completed during fetal development. Age-dependent defects of maternal origin might, however, be explained in part by the progressive loss of oocytes during the mother's reproductive life. A large number of oocytes undergo the initial stages of maturation each month, but typically only one completes maturation and is ovulated while the majority are discarded, probably by an apoptotic mechanism. Here we explore the possibility that the monthly choice of oocytes to undergo maturation is influenced by subtle phenotypic characters of those oocytes that may bear genetic defects such as trisomy 21. We have generated a mathematical model to describe the loss kinetics for such mutant oocytes relative to the overall pool of resting oocytes, and we assess evolutionary strategies that would favor their utilization faster than, at the same rate as, or slower than the normal oocytes. This formulation reveals that the slower-rate scheme would effectively diminish the utilization of mutant oocytes in young mothers but would increase the risk of related birth defects for older mothers. Accordingly, we propose that natural selection should have favored the delayed utilization of defective oocytes in a primitive high-mortality culture, but that this evolutionary strategy would be outmoded for modern society, because it would lead to an increased frequency of birth defects for older mothers.

Computation of multilocus prior probability of autozygosity for complex inbred pedigrees

Homozygosity mapping is a very powerful method for mapping rare recessive diseases in humans. In many applications, it is often desirable to compute prior (or unconditional) multilocus probability of autozygosity for inbred pedigrees. This paper proposes a simple yet powerful method for computing the prior multilocus autozygosity probability for complex inbred pedigrees. The method has an added feature of providing explicit multilocus autozygosity probability in terms of recombination fractions, if desired. An example is presented to illustrate the method.

Familial aggregation of environmental risk factors and familial aggregation of disease

Almost all human diseases have been shown to aggregate familially to some degree. This familiality is generally taken as evidence for the existence of a genetic etiologic mechanism or environmental factors common to family members, or a combination of both. It has been argued that for a disease with strong familial aggregation, environmental risk factors alone are unlikely to account for such strong aggregation, unless the presumed environmental risk factors are associated with enormous risk. This paper revisits this issue through the use of a novel statistical model. Ascertainment bias aside, the author demonstrates that familial aggregation could be explained by multiple interactive risk factors, each of which may confer a low disease risk and thus contribute only a minuscule portion to disease familiality. For example, two correlated risk factors (r=0.5), each with a relative risk of 5 and acting multiplicatively, could give rise to a sibling relative risk of 1.96. Therefore, it may not be sufficient to argue for a genetic component for a disease based solely on the notion that no high risk environmental factors have been found. In view of this, there is a need to examine carefully the roles of multiple environmental risk factors in disease familiality.

Threshold distributions of phenylthiocarbamide (PTC) in the Chinese population

The ability to taste phenylthiocarbamide (PTC) is a well-documented Mendelian trait. Mapping and cloning the gene(s) responsible for the PTC tasting ability would help to delineate the molecular basis for the variations in PTC tasting ability in humans and to shed new light on taste chemosensory functions. In view of the spectacular successes in genome science, the positional cloning strategy seems to be a feasible approach to the isolation of the gene(s) underlying the PTC tasting ability. As a first step toward mapping the gene(s), we collected PTC taste threshold data on 106 individuals, most of them being university students, in Shanghai, China. Using various parametric and nonparametric statistical methods, we have found that the data set is best described by a bimodal distribution. The frequency of PTC nontasters is estimated to be 10%. This is consistent with the view that the PTC nontasting ability follows a recessive mode of inheritance. Several authors had previously reported PTC data on Chinese living outside China. Our data are, to our knowledge, the first ever collected from the Chinese population within China.

The power of linkage detection by the transmission/disequilibrium tests

Despite growing interest in the use of transmission/disequilibrium test (TDT)-type analysis in association studies, there has been surprisingly scant attention paid to the issues as to what factors affect the power of the TDT for linkage detection. We demonstrate in this paper that the power is a function of several genetic parameters including the recombination fraction, penetrance, the age of mutant disease allele, marker allele frequency, recurrent mutation rates at marker and/or disease locus, and initial linkage disequilibrium. In general, TDT has greater power to detect linkage for a 'recessive'-type model than for a 'dominant'-type model. Its power also is higher when there is greater differential in marker allele frequency between disease and normal chromosomes. And since the presence of marker mutation and/or recurrent mutation at the disease locus, or the age of disease mutation, or the initial incomplete linkage disequilibrium, all hasten the process to reach linkage equilibrium, all of them can affect the power of TDT to detect linkage. The effect of marker mutation rate or the mutation rate at the disease locus can be minimal if mutation rates are low. The results on the impact of recombination fraction and of age of mutation on the power of TDT in linkage detection seem to be disheartening for gene mappers of complex diseases: for a disease with small genetic influence, a vastly large sample size is needed to detect the linkage, if the marker is not very close to the disease locus. This is particularly true if the disease is 'old'.

Linkage analysis of human leukocyte antigen (HLA) markers in familial psoriasis: strong disequilibrium effects provide evidence for a major determinant in the HLA-B/-C region

Although psoriasis is strongly associated with certain human leukocyte antigens (HLAs), evidence for linkage to HLA markers has been limited. The objectives of this study were (1) to provide more definitive evidence for linkage of psoriasis to HLA markers in multiplex families; (2) to compare the major HLA risk alleles in these families with those determined by previous case-control studies; and (3) to localize the gene more precisely. By applying the transmission/disequilibrium test (TDT) and parametric linkage analysis, we found evidence for linkage of psoriasis to HLA-C, -B, -DR, and -DQ, with HLA-B and -C yielding the most-significant results. Linkage was detectable by parametric methods only when marker-trait disequilibrium was considered. Case-control association tests and the TDT identified alleles belonging to the EH57.1 ancestral haplotype as the major risk alleles in our sample. Among individuals carrying recombinant ancestral haplotypes involving EH57. 1, the class I markers were retained selectively among affecteds four times more often than among unaffecteds; among the few affected individuals carrying only the class II alleles from the ancestral haplotype, all but one also carried Cw6. These data show that familial and "sporadic" psoriasis share the same risk alleles. They also illustrate that substantial parametric linkage information can be extracted by accounting for linkage disequilibrium. Finally, they strongly suggest that a major susceptibility gene resides near HLA-C.

Inflation of sibling recurrence-risk ratio, due to ascertainment bias and/or overreporting

One widely used measure of familial aggregation is the sibling recurrence-risk ratio, which is defined as the ratio of risk of disease manifestation, given that one's sibling is affected, as compared with the disease prevalence in the general population. Known as lambdaS, it has been used extensively in the mapping of complex diseases. In this paper, I show that, for a fictitious disease that is strictly nongenetic and nonenvironmental, lambdaS can be dramatically inflated because of misunderstanding of the original definition of lambdaS, ascertainment bias, and overreporting. Therefore, for a disease of entirely environmental origin, the lambdaS inflation due to ascertainment bias and/or overreporting is expected to be more prominent if the risk factor also is familially aggregated. This suggests that, like segregation analysis, the estimation of lambdaS also is prone to ascertainment bias and should be performed with great care. This is particularly important if one uses lambdaS for exclusion mapping, for discrimination between different genetic models, and for association studies, since these practices hinge tightly on an accurate estimation of lambdaS.

Linkage disequilibrium measures for fine-scale mapping: a comparison

We investigate properties of simple linkage disequilibrium mapping for five measures in the presence of mutation at the marker and/or the disease locus and of initial incomplete linkage disequilibrium. In contrast to the stimulation approach that Devlin and Risch used, we calculate the expected values of various linkage disequilibrium measures under different assumptions based on a framework for linkage disequilibrium mapping. These expected values clearly demonstrate the expected performance of these measures. We find that the impact of marker mutation on their performance depends on the magnitude of the mutation relative to the proximity of the marker (i.e. recombination fraction between the marker and the disease locus). In the presence of recurrent mutation at the marker and/or disease locus, the performance of all measures, including the robust one, depends on the marker allele frequency. The initial incomplete linkage disequilibrium could render all measures useless. These expected values also show clearly why in Devlin and Risch's simulation some measures performed very badly under certain circumstances.

Estimating the age of mutant disease alleles based on linkage disequilibrium

With more and more disease genes being mapped and/or cloned, there is a growing interest in dating the age of underlying mutations. The knowledge of the age of mutation is important to finely map disease genes by linkage disequilibrium mapping. It would also help us understand the origin, evolution, and dispersion of the mutant disease genes. Despite increasing interests in dating disease mutations, the development of appropriate statistical methods is largely fragmentary, and there is a lack of systematic treatment of the topic. We propose two classes of methods for estimating the age of mutant allele at the disease locus based on linked marker data. Our methods can not handle only single-locus marker data, but also multi-locus marker data as well. Moreover, our methods can be used even when the location of the disease locus is unknown, and/or when there are mutations at the marker or disease locus. We show that some previous results are special cases of our methods. We also derive a recursive equation previously obtained by Serre et al. [Hum Genet 1990;84:449-454] and provide an explicit solution to the equation. To illustrate our methods, we applied them to two groups of data sets, one is cystic fibrosis data collected from several European populations, and the other is data on several genetic diseases (diastrophic dysplasia, progressive myoclonus epilepsy, congenital chloride diarrhea, and Batten disease) all collected from the Finnish population. The former data set allows us to trace the origin and dispersion of the most common mutation for cystic fibrosis. The latter provides an opportunity to examine whether all mutations for these diseases have the same age.

Evidence for two psoriasis susceptibility loci (HLA and 17q) and two novel candidate regions (16q and 20p) by genome-wide scan

In a 12.5 cM genome-wide scan for psoriasis susceptibility loci, recombination-based tests revealed linkage to the HLA region (Zmax = 3.52), as well as suggestive linkage to two novel regions: chromosome 16q (60-83.1 cM from pter, Zmax = 2.50), and chromosome 20p (7.5-25 cM from pter, Zmax = 2.62). All three regions yielded P values < or = 0.01 by non-parametric analysis. Recombination-based and allele sharing methods also confirmed a previous report of a dominant susceptibility locus on distal chromosome 17q (108.2 cM from pter, Zmax = 2.09, GENEHUNTER P = 0.0056). We could not confirm a previously reported locus on distal chromosome 4q; however, a broad region of unclear significance was identified proximal to this proposed locus (153.6-178.4 cM from pter, Zmax = 1.01). Taken together with our recent results demonstrating linkage to HLA-B and -C, this genome-wide scan identifies a psoriasis susceptibility locus at HLA, confirms linkage to 17q, and recommends two novel genomic regions for further scrutiny. One of these regions (16q) overlaps with a recently-identified susceptibility locus for Crohn's disease. Psoriasis is much more common in patients with Crohn's disease than in controls, suggesting that an immunomodulatory locus capable of influencing both diseases may reside in this region.

Identification of the human chromosomal region containing the iridogoniodysgenesis anomaly locus by genomic-mismatch scanning

Genome-mismatch scanning (GMS) is a new method of linkage analysis that rapidly isolates regions of identity between two genomes. DNA molecules from regions of identity by descent from two relatives are isolated based on their ability to form extended mismatch-free heteroduplexes. We have applied this rapid technology to identify the chromosomal region shared by two fifth-degree cousins with autosomal dominant iridogoniodysgenesis anomaly (IGDA), a rare ocular neurocristopathy. Markers on the short arm of human chromosome 6p were recovered, consistent with the results of conventional linkage analysis conducted in parallel, indicating linkage of IGDA to 6p25. Control markers tested on a second human chromosome were not recovered. A GMS error rate of approximately 11% was observed, well within an acceptable range for a rapid, first screening approach, especially since GMS results would be confirmed by family analysis with selected markers from the putative region of identity by descent. These results demonstrate not only the value of this technique in the rapid mapping of human genetic traits, but the first application of GMS to a multicellular organism.

Fine-scale genetic mapping based on linkage disequilibrium: theory and applications

Linkage-disequilibrium mapping (LDM) recently has been hailed as a powerful statistical method for fine-scale mapping of disease genes. After reviewing its historical background and methodological development, we present a general, mathematical, and conceptually coherent framework for LDM that incorporates multilocus and multiallelic markers and mutational processes at the marker and disease loci. With this framework, we address several issues relevant to fine-scale mapping and propose some efficient computational methods for LDM. We implement various LDM methods that incorporate population growth, recurrent mutation, and marker mutations, on the basis of a general framework. We demonstrate these methods by applying them to published data on cystic fibrosis, Huntington disease, Friedreich ataxia, and progressive myoclonus epilepsy. Since the genes responsible for these diseases all have been cloned, we can evaluate the performance of our methods and can compare ours with that of other methods. Using the proposed methods, we successfully and accurately predicted the locations of genes responsible for these diseases, on the basis of published data only.

Genes preserved in relatives

The genes of an individual are said to be preserved in his relatives if they possess, collectively, all copies of his genes. We present a method for computing the probability that an individual's genes are preserved in his relatives. Using this method, we compute gene preservation probabilities (up to three linked loci) for a variety of relationships for humans and for haplodiploid species. The results suggest that some widely held notions in ethology and sociobiology seem to be questionable. From the gene preservation viewpoint, two brothers are far from enough to justify the sacrifice of one's own life, because the probability that an individual's genes are preserved in his two siblings is dismally small. The precise probability that an individual's genes are all preserved in a group of his relatives depends on the precise specification of the pedigree structure. We also demonstrate that, for a hymenopteran female, there is no practical difference, in terms of gene preservation probability, between helping her sisters to breed and breeding her own offspring. In fact, since the genes of her sister will be either lost or preserved in her nieces/nephews, it is more appropriate to compare the probability of preserving her genes through her own offspring with that through her nieces/nephews. We show that her chance of preserving all her genes is much higher if she chooses to breed her own offspring instead of helping her sister.

Fine-scale mapping of quantitative trait loci using historical recombinations

With increasing popularity of QTL mapping in economically important animals and experimental species, the need for statistical methodology for fine-scale QTL mapping becomes increasingly urgent. The ability to disentangle several linked QTL depends on the number of recombination events. An obvious approach to increase the recombination events is to increase sample size, but this approach is often constrained by resources. Moreover, increasing the sample size beyond a certain point will not further reduce the length of confidence interval for QTL map locations. The alternative approach is to use historical recombinations. We use analytical methods to examine the properties of fine QTL mapping using historical recombinations that are accumulated through repeated intercrossing from an F2 population. We demonstrate that, using the historical recombinations, both simple and multiple regression models can reduce significantly the lengths of support intervals for estimated QTL map locations and the variances of estimated QTL map locations. We also demonstrate that, while the simple regression model using historical recombinations does not reduce the variances of the estimated additive and dominant effects, the multiple regression model does. We further determine the power and threshold values for both the simple and multiple regression models. In addition, we calculate the Kullback-Leibler distance and Fisher information for the simple regression model, in the hope to further understand the advantages and disadvantages of using historical recombinations relative to F2 data.

Statistical methods for gene map construction by fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) provides an efficient and powerful technique for ordering loci both on metaphase chromosomes and in less condensed interphase chromatin. Two-color metaphase FISH can be used to order pairs of loci relative to the centromere; two- and three-color interphase FISH can be used to accurately order trios of loci spaced within 1 Mb relative to one another. Loci separated by a distance > 1-2 Mb exhibit chromatin loops that often give rise to a statistically significant but incorrect order. We derive Bayesian methods for selecting the best locus order based on microscopic evaluation for each of these types of FISH mapping data. We then describe how the results from several two- and three-locus analyses can be combined to evaluate the approximate posterior probability of a given multilocus order within the limits of the technology utilized. These methods directly address the question of interest: What is the probability that the inferred two-, three-, or multilocus order actually is correct? We illustrate our analysis methods by applying them to previously described FISH mapping data of 14 markers in the BRCA1 region on chromosome 17q12-q21. We also propose design strategies to order a group of closely spaced (< 1 Mb) loci, two and three loci at a time, using a bisection strategy for two-color FISH data and a trisection strategy for three-color FISH data. These strategies have the best worst-case performance for ordering a new locus relative to a group of ordered loci and are nearly optimal for ordering a group of loci of unknown order. These, in conjunction with physical mapping strategies, provide efficient and reliable methods for gene map construction by FISH.

Variation in genetic identity among relatives

Genetic identity, or genetic relatedness, among relatives, is a key concept in kin recognition, which in turn is important in models for inclusive fitness and inbreeding avoidance. A mathematical definition is presented for the genetic identity based on the proportion of genome shared identical by descent by two relatives. The method of Guo [Am J Hum Genet 1995;56:1468-1476] is used to compute the variance of the genetic identity for various types of relationships. The method is versatile and can handle any kind of relationship. To illustrate the method, the standard errors of the genetic identity using published human genetic maps are computed.

Gametogenesis processes and multilocus gene identity by descent

With few exceptions, the determination of unconditional probability of genes shared identical by descent (IBD) by relatives can be very difficult, especially if the relationship is complex or if multiple loci are involved. It is particularly difficult if one needs the IBD probability in a explicit form, expressed in terms of interlocus recombination fractions. In this paper, I will further extend the concept of gametogenesis process introduced elsewhere and indicate that it completely determines the gene IBD events of interest in pedigrees. I will demonstrate that the gametogenesis process not only serves as a convenient conceptual framework in considering IBD events in pedigrees but also provides a simple yet powerful tool to solve a wide range of seemingly difficult problems. In particular, I consider the problem of multilocus IBD probability for relative pairs, k siblings, and a group of pedigree members. In addition, I consider the problem of multilocus autozygosity probability and the problem of gene preservation in close relatives.

Affected-sib-pair interval mapping and exclusion for complex genetic traits: sampling considerations

We describe an extension of Risch's [(1990a,b) Am J Hum Genet 46:222-228, 229-241] method of linkage detection and exclusion for complex genetic traits. The method uses interval mapping to infer disease locus identity-by-descent (IBD) sharing for affected sib pairs (ASPs) based on marker information for the ASP and other genotyped family members. The method is likelihood based, and makes use of Risch's parameterization in terms of recurrence risk ratios for relatives. We describe specific linkage detection and exclusion tests for use as genome screening tools to prioritize genomic regions for further study. We also examine issues of optimal study design. We advocate initially typing a large panel of ASPs (and no additional family members) with a map of genetic markers evenly spaced at 10-20-cM intervals. We recommend a screening procedure that 1) investigates further all regions with maximum lod scores greater than 1 and 2) excludes from consideration those regions that result in lod scores less than -2 at the smallest genetic effect that is viewed as important to detect. Further investigation of an interval might include typing other available families or family members, typing additional markers in the interval, and carrying out further statistical analyses. This strategy is efficient in the number of genotypings required and focuses attention on regions most likely to harbor a disease gene with a substantial impact on disease risk, while resulting in the pursuit of a manageable number of false-positive linkage results. Modification may be required if insufficient ASPs are available or if families come from a significantly admixed population.

Scanning chromosome 17 for psoriasis susceptibility: lack of evidence for a distal 17q locus

Evidence for a genetically heterogeneous psoriasis susceptibility locus on distal human chromosome 17q has recently been reported [Science 1994;264:1141]. Making use of an independently ascertained collection of 24 multiplex psoriasis kindreds, we have performed a genotyping scan of chromosome 17 using 12 microsatellite markers and analyzed the data using parametric (lod score) as well as novel nonparametric methods. Pairwise lod scores revealed no evidence for linkage to the previously implicated marker D17S784 under any of eight models varying in mode of inheritance, penetrance, and sporadic cases. Homogeneous linkage to D17S784 could be excluded under all four autosomal dominant models tested (Z < - 5.8 at theta = 0.05), and there was no evidence for genetic heterogeneity. All other chromosome 17 markers tested also failed to detect evidence for linkage in any of the kindreds under either a dominant or a recessive model. Although further analysis using affected sib pair methods provided no statistically significant evidence for linkage to any chromosome 17 marker, a cluster of three distal 17q loci displayed a trend towards greater than expected allele-sharing values (observed/expected = 1.10-1.14). These results do not formally confirm the existence of a psoriasis susceptibility locus on the distal long arm of human chromosome 17, but are suggestive of its possible involvement under a polygenic model, warranting its further investigation in familial psoriasis.

Proportion of genome shared identical by descent by relatives: concept, computation, and applications

One widely used measure of genetic similarity for pairs of relatives is gene identity-by-descent (IBD) sharing. Genes that are copies of a single gene in a common ancestor of the individuals who now carry them are said to be IBD. One obvious extension of the IBD concept is IBD gene(s) shared by more than two individuals. In this paper, I further extend the gene IBD concept to the proportion of genomes shared IBD by every member of a group of relatives. Genome may refer either to the entire autosomal genome or to one or more chromosomal segments or regions with known lengths. Consideration of a genome instead of one or two loci has several advantages. I present a model to describe the crossover process, based on the work of K. P. Donnelly. On the basis of this model, I give a mathematical definition of the proportion of genome shared IBD by relatives, or IBDP for short. Since the distribution of the IBDP is in general very difficult to determine, and since in most applications the mean and variance of the IBDP will suffice, I then provide a method for computing the first two moments of the IBDP. Applications to assessing gene survival, to genetic resemblance between two relatives, and to gene mapping are illustrated with examples. Finally, I discuss the utility of the IBDP in other areas.

Detection of genome similarity as an exploratory tool for mapping complex traits

For one- and two-trait-locus models, we show that the lod score based on affected relative pairs or trios is a monotonically increasing function of the genome similarity measured by the proportion of alleles shared identical by descent (IBD) conditional on observed marker data. These results can be generalized to multitrait-locus models. Thus, we can use conditional probability of genes shared IBD as a tool to reveal chromosomal segments that are likely to harbor the genes underlying the complex traits.

Proportion of genes survived in offspring conditional on inheritance of flanking markers

In mammalian genetics and perhaps in human genetics as well, it is an interesting question as to how many offspring are needed in order to have a desired chance of preserving part of the entire genome of an individual. A more practical and perhaps more important question is: given k children and DNA marker data on a particular region of interest, what proportion of one's genes has been actually passed on to his children? To answer this question, I define the concept of identity by descent proportion, or IBDP for short. The IBDP is defined to be the proportion of genetic material shared identical by descent by a group of relatives in a specified chromosomal region. I provide a novel approach to computing the mean and variance of IBDP for k (> or = 2) half-sibs based on marker data, thus providing a means to compute the mean and variance of proportion of genes survived. I first show that each chromosome in an offspring can be represented by a two-state Markov chain, with the time parameter being the map distance along the chromosome. On this basis, I will show that IBDP can be written as a stochastic integral and that the computation of the EIBDP can be reduced to evaluating an integral of some elementary functions. Numerical examples are provided to illustrate the calculation.