Damage assessment in structures using artificial neural network working and a hybrid stochastic optimization.

Artificial neural network (ANN) has been commonly used to deal with many problems. However, since this algorithm applies backpropagation algorithms based on gradient descent (GD) technique to look for the best solution, the network may face major risks of being entrapped in local minima. To overcome those drawbacks of ANN, in this work, we propose a novel ANN working parallel with metaheuristic algorithms (MAs) to train the network. The core idea is that first, (1) GD is applied to increase the convergence speed. (2) If the network is stuck in local minima, the capacity of the global search technique of MAs is employed. (3) After escaping from local minima, the GD technique is applied again. This process is applied until the target is achieved. Additionally, to increase the efficiency of the global search capacity, a hybrid of particle swarm optimization and genetic algorithm (PSOGA) is employed. The effectiveness of ANNPSOGA is assessed using both numerical models and measurement. The results demonstrate that ANNPSOGA provides higher accuracy than traditional ANN, PSO, and other hybrid ANNs (even a higher level of noise is employed) and also considerably decreases calculational cost compared with PSO.

216 cases of pancreaticoduodenectomy: risk factors for postoperative complications.

BACKGROUND/AIMS: Surgical resection remains the best treatment for patients with periampullary tumors. Many series have been reported with low or zero mortality, however, high incidence of complications is the rule. This study aims to present the results of pancreaticoduodenectomy and factors predisposing to postoperative complications, especially pancreatic leak, at our center. METHODOLOGY: Between January 2000 and December 2006, 216 periampullary tumors were treated by Whipple pancreaticoduodenectomy. Pancreaticogastrostomy was done in 183 patients and pancreaticojejunostomy in 33 patients. Hospital mortality and surgical complications were recorded with special emphasis on pancreatic leak. All specimens were histologically examined for the presence and origin of malignant tissue. RESULTS: The mean age was 58 years and male to female ratio was 2:1. The commonest symptom was jaundice (97.7%) followed by abdominal pain (74%). Operative mortality in 7 patients (3.2%). 71 (33%) patients developed 1 or more complications, pancreatic leak occurred in 23 (10.6%) patients, abdominal collection in 23 patients (10.6%) and delayed gastric emptying in 19 (8.8%) patients. Factors that influenced the development of postoperative complications included type of pancreaticoenteric anastomosis, pancreatic texture and intraoperative blood transfusion of 4 or more blood units. Pancreatic leak was commoner with PJ (p=0.001), soft pancreatic texture (p=0.008), intraoperative blood transfusion of 4 or more units (p<0.0001). Periampullary adenocarcinoma was found in 204 (94.4%) patients, chronic pancreatitis in 9 (4.2%) patients, 2 patients with solid and papillary neoplasm, and 1 patient with NHL (Non-Hodgkin's Lymphoma). CONCLUSIONS: Surgery is the only hope for patients with periampullary tumors. Postoperative complications after pancreaticoduodenectomy depend largely on surgical technique and can be reduced reasonably with the adoption of pancreaticogastrostomy, which is safer and easier to learn than pancreaticojejunostomy.

Multivariate analysis of bcl-2, apoptosis, P53 and HER-2/neu in breast cancer: a short-term follow-up.

BACKGROUND: Several molecular genetic alterations in breast cancer, including aneuploidy, altered apoptosis, aberrant expression of p53, HER-2/neu and Bcl-2, have been associated with poor prognosis in breast cancer patients. To determine the importance of molecular-genetic factors relative to more traditional surgical-pathological prognostic factors, multivariate analysis was performed. PATIENTS AND METHODS: Ninety-four fresh tissue samples of primary breast carcinoma were studied with flow cytometry for DNA ploidy. On the same specimens, steroid hormone receptors (ER and PR) were measured in the cytosol fraction using Abbott ELISA assays. HER-2/neu was determined in the membrane fraction and mutant p53 protein in the nuclear fraction, both, by Oncogene Science ELIZA procedures. Bcl-2 and apoptosis (cell death) were measured in cell lysates by Oncogene Science & Boehringer Mannheim ELISA assays. In addition, information regarding surgical-pathological features of the tumor was obtained. Multivariate analysis using an unconditional logistic regression model was done to identify variables predictive of poor prognosis. RESULTS: Using univariate analysis, histological grade, tumor stage, lymph node status, HER-2/neu and mutant p53 were predictive of poor short-term prognosis. By multivariate analysis, tumor stage, lymph node status and HER-2/neu were independent factors. Grade subgroup analysis versus time of relapse, illustrated a predictive value of Bcl-2 in only low-grade tumors while apoptosis was significant in high-grade type. CONCLUSION: Among a panel of molecular-genetic factors investigated, HER-2/neu was the most strongly predictive of poor short-term prognosis in breast cancer. Patients with HER-2/neu-positive tumors can benefit from Herceptin therapy.

Outcome of right hepatectomy for living liver donors: a single Egyptian center experience.

BACKGROUND: This study aims to evaluate living liver donor outcome after right hepatectomy in a single Egyptian center. PATIENTS AND METHODS: Between April 2004 and July 2010, 100 living donors underwent right hepatectomy. Their medical records and postoperative follow-up visits were retrospectively revised. Perioperative complications were reported. Postoperative complications were classified according to the five tier version of Clavien system. RESULTS: There were 71 males and 29 females. The mean age was 27.6 ± 7.4 years. The mean graft weight was 999 ± 167 g and the mean volume percent of the remaining liver was 36.8 ± 8%. The mean ICU and hospital stay were 2.6 ± 2.7 and 12.4 ± 9.1, respectively. A total of 57 complications developed in 38 donors (38%). The commonest complication type was biliary complications. There were 22 grade I, 6 grade II, 15 grade IIIa, 12 grade IIIb, 1 grade IVa, and 1 grade V complications. One donor died due to posttransfusion ARDS on the 30th postoperative day. On follow-up, no donor developed long lasting disability. A donor died in a road traffic accident 1 year after donation. DISCUSSION AND CONCLUSIONS: Donor right hepatectomy is not an entirely safe procedure. Biliary complications are the commonest early postoperative complications.