An actor-critic framework based on deep reinforcement learning for addressing flexible job shop scheduling problems

With the rise of Industry 4.0, manufacturing is shifting towards customization and flexibility, presenting new challenges to meet rapidly evolving market and customer needs. To address these challenges, this paper suggests a novel approach to address flexible job shop scheduling problems (FJSPs) through reinforcement learning (RL). This method utilizes an actor-critic architecture that merges value-based and policy-based approaches. The actor generates deterministic policies, while the critic evaluates policies and guides the actor to achieve the most optimal policy. To construct the Markov decision process, a comprehensive feature set was utilized to accurately represent the system's state, and eight sets of actions were designed, inspired by traditional scheduling rules. The formulation of rewards indirectly measures the effectiveness of actions, promoting strategies that minimize job completion times and enhance adherence to scheduling constraints. The experimental evaluation conducted a thorough assessment of the proposed reinforcement learning framework through simulations on standard FJSP benchmarks, comparing the proposed method against several well-known heuristic scheduling rules, related RL algorithms and intelligent algorithms. The results indicate that the proposed method consistently outperforms traditional approaches and exhibits exceptional adaptability and efficiency, particularly in large-scale datasets.

Comparison of the Pretzelflex Retractor and Nathanson Retractor in Laparoscopic Sleeve Gastrectomy Surgery

PURPOSE

Retraction of the left lobe of the liver is an important step in most bariatric surgical procedures. The left lobe of the liver may be enlarged, and laceration, hematoma, or necrosis may develop in the liver due to retraction. In this study, the results of use of the Nathanson retractor (NR) and PretzelFlex retractor (PFR) in the patients undergoing laparoscopic sleeve gastrectomy (LSG) were compared.

MATERIALS AND METHODS

The patients who underwent LSG were divided into three groups based on the type of liver retraction device used. Group 1: NR was used fixed during the operation; Group 2: PF retractor was used; Group 3: NR were used only for fundus dissection and when necessary. All groups were evaluated in terms of demographic characteristics, liver function tests, and developing complications.

RESULTS

The study was conducted with a total of 120 consecutive patients. Operation time in the second group was found to be significantly lower than the other two groups (p = 0.009; p = 0.001; p < 0.01). The duration of retractor use in the first group was significantly higher than the other two groups (p = 0.001; p = 0.001; p < 0.01). While aspartate aminotransferase (AST) values were found to be high in Group 1, alanine aminotransferase (ALT) values were found to be high in Groups 1 and 3.

CONCLUSION

PFR has shorter operating and retraction times. It causes less measurable liver damage. Although the NR will be used, intermittent use causes less damage to the liver as in PFR.

Cell and Tissue Therapy for the Treatment of Chronic Liver Disease

Liver disease is an important clinical problem, impacting 600 million people worldwide. It is the 11th-leading cause of death in the world. Despite constant improvement in treatment and diagnostics, the aging population and accumulated risk factors led to increased morbidity due to nonalcoholic fatty liver disease and steatohepatitis. Liver transplantation, first established in the 1960s, is the second-most-common solid organ transplantation and is the gold standard for the treatment of liver failure. However, less than 10% of the global need for liver transplantation is met at the current rates of transplantation due to the paucity of available organs. Cell- and tissue-based therapies present an alternative to organ transplantation. This review surveys the approaches and tools that have been developed, discusses the distinctive challenges that exist for cell- and tissue-based therapies, and examines the future directions of regenerative therapies for the treatment of liver disease.

Thoracic duct injury after decortication of lung, new technique to repair thoracic duct in this challenging situation: A case report

BACKGROUND

Chylothorax is a rare form of pleural effusion that can be associated with both traumatic and non-traumatic causes. Very few patients respond to conservative line of therapy. Thoracic duct ligation is often the treatment of choice in post-surgical patients; however, the optimal treatment of this disease process after traumatic injury remains unclear.Case presentation: We present the case of a 46-year-old woman with thoracic duct injury secondary to decortication for post-pneumonic empyema. Conservative therapy and pleurodesis done twice failed. She developed severe cachexia losing 15 kg in 30 days. She was referred to our center for ligation of thoracic duct. Preoperative lymphangiography located the duct injury in upper part of mediastinum. Computerized tomography scan of chest showed collapse of left lower lobe and thickened left pleura, indicating a significant pericardial effusion. She underwent decortication of left lung, pericardial window, and native pericardial patch repair of thoracic duct.Results and Conclusions: In this unusual and complex case, successful resolution of the chyle leak was achieved with new surgical technique of patch repair. The patient recovered well and was now on a normal diet. She has put on 12 kg in four months. We have avoided late complications of thoracic duct ligation by this technique. This nouvelle technique may be recommended as it is simple and effective. Ligation of thoracic duct carries late complications. Isolating right lung by double lumen tube may cause severe hypoxia as left-sided lung is not expanded as in this case.

Hepatocyte transplantation: Consider infusion before incision

Human hepatocyte transplantation is undergoing study as a bridge, or even alternative, to orthotopic liver transplantation (OLT). This technique has undergone multiple developments over the past thirty years in terms of mode of delivery, source and preparation of cell cultures, monitoring of graft function, and use of immunosuppression. Further refinements and improvements in these techniques will likely allow improved graft survival and function, granting patients higher yield from this technique and potentially significantly delaying need for OLT.

Laparoscopic Adjustable Gastric Band Slippage Rates Following Laparoscopic Gastric Band Insertion: a Single Centre Experience

INTRODUCTION

Laparoscopic adjustable gastric bands (LAGB) are placed around the superior aspect of the stomach to aid weight loss and co-morbidity resolution in morbidly obese patients. Slippage of the LAGB from its original position to lower in the fundus of the stomach leads to gastric obstruction, and sometimes ischaemia or perforation, necessitating LAGB repositioning or removal. This study aimed to identify the incidence of LAGB slippage, as well as predisposing factors that may influence its development.

METHODS

All LAGBs inserted at one centre, via a pars flaccida technique, by four Bariatric specialist consultants, were reviewed utilising a prospectively maintained Bariatric database, computer records and case notes review.

RESULTS

Seven hundred nineteen LAGBs were inserted and 33 slips treated; however, only 22 slips had their LAGB inserted at our centre (local slip rate 3.1 %). Multivariate analysis demonstrated a significant association between LAGB slip and younger median age at LAGB insertion (41 years slip vs. 45 years non-slip; p = 0.027), higher median total excess weight loss (64 % slip vs. 36 % non-slip; p < 0.001) and higher mean excess weight loss per month (2.41 % slip vs. 1.00 % non-slip; p < 0.001). There was no significant effect by sex, BMI at insertion or band type.

CONCLUSIONS

Band slips are associated with greater excess weight loss and younger age. Larger studies may be necessary to further elucidate the risk factors contributing to, and mechanisms of, band slippage.

Response of Cultured Fetal and Adult Rat Hepatocytes to Growth Factors and Cyclosporine

Hepatocyte transplantation is a promising alternative to orthotopic liver transplantation in experimental animal models with genetic disorders of liver metabolism and liver failure. Fetal hepatocytes have several characteristics that make them potentially suitable as donor cells. In contrast to adult hepatocytes, fetal hepatocytes are thought to be highly proliferative, which may facilitate engraftment, expansion of transplanted cell population, and gene transfer requiring active DNA synthesis. The present study was undertaken to evaluate the proliferative capacity of fetal and adult rat hepatocytes under standardized culture conditions. Fetal (20 days of gestation) and adult hepatocytes were cultured in serum-free media at low densities and treated with growth factors. Proliferation was assessed by [3H]-thymidine incorporation and cell cycle analysis by flow cytometry. In nonstimulated cells, DNA synthesis at 4 h was about × 100 higher and after 10 days in culture ×20 higher in fetal compared to adult hepatocytes. When epidermal growth factor (EGF) was added, maximal DNA synthesis in fetal hepatocytes was seen at 48 h, whereas in adult hepatocytes at 72 h. For adult hepatocytes, the average increase compared to untreated cells was × 13.8 with EGF, ×18.5 with transforming growth factor alpha (TGF-α), and ×7.6 with hepatocyte growth factor (HGF). For fetal hepatocytes, the increase was twofold with either EGF, TGF-α or HGF. EGF-, TGF-α- and HGF-dependent DNA synthesis was inhibited by transfroming growth factor beta-1 (TGF-β1) in both fetal and adult hepatocyte cultures; this antiproliferative effect was significantly stronger in adult hepatocyte cultures. With cyclosporine, EGF-, TGF-α- and HGF-dependent DNA synthesis in fetal hepatocyte cultures decreased by 36–46%, whereas in adult hepatocytes by 19–27%. These results show that in contrast to adult hepatocytes, fetal hepatocytes have high spontaneous proliferative activity independently of growth factors and are relatively resistant to the inhibitory effect of TGF-β1. It was also found that cyclosporine suppresses proliferation of cultured fetal hepatocytes.

Laparoscopic versus open appendectomy: a retrospective cohort study assessing outcomes and cost-effectiveness

BACKGROUND

Appendectomy is the most common surgical procedure performed in emergency surgery. Because of lack of consensus about the most appropriate technique, appendectomy is still being performed by both open (OA) and laparoscopic (LA) methods. In this retrospective analysis, we aimed to compare the laparoscopic approach and the conventional technique in the treatment of acute appendicitis.

METHODS

Retrospectively collected data from 593 consecutive patients with acute appendicitis were studied. These comprised 310 patients who underwent conventional appendectomy and 283 patients treated laparoscopically. The two groups were compared for operative time, length of hospital stay, postoperative pain, complication rate, return to normal activity and cost.

RESULTS

Laparoscopic appendectomy was associated with a shorter hospital stay (2.7 ± 2.5 days in LA and 1.4 ± 0.6 days in OA), with a less need for analgesia and with a faster return to daily activities (11.5 ± 3.1 days in LA and 16.1 ± 3.3 in OA). Operative time was significantly shorter in the open group (31.36 ± 11.13 min in OA and 54.9 ± 14.2 in LA). Total number of complications was less in the LA group with a significantly lower incidence of wound infection (1.4 % vs 10.6 %, P <0.001). The total cost of treatment was higher by 150 € in the laparoscopic group.

CONCLUSION

The laparoscopic approach is a safe and efficient operative procedure in appendectomy and it provides clinically beneficial advantages over open method (including shorter hospital stay, decreased need for postoperative analgesia, early food tolerance, earlier return to work, lower rate of wound infection) against only marginally higher hospital costs.

TRIAL REGISTRATION

NCT02867072 Registered 10 August 2016. Retrospectively registered.

Elective laparoscopic cholecystectomy without intraoperative cholangiography: role of preoperative magnetic resonance cholangiopancreatography - a retrospective cohort study

Background

Laparoscopic cholecystectomy (LC) is the standard treatment for gallbladder diseases. Intraoperative cholangiography (IOC) can reduce biliary complications of LC; however, with the emergence of magnetic resonance cholangiopancreatography (MRCP), IOC nowadays is faced with unprecedented challenge. The purpose of this study is to evaluate whether preoperative MRCP can safely replace IOC during elective LC in terms of retained common bile duct (CBD) stones and bile duct injury (BDI).

Methods

A retrospective study on candidates for elective LC who underwent IOC or preoperative MRCP between January 2009 and December 2014 was conducted.

Results

In the IOC group, 1972 patients underwent LC and 213 required IOC. In the MRCP group, 2268 patients underwent LC and 257 required MRCP. In the IOC group, the rate of retained CBD stones was 0.45 % without IOC and 1.41 % with IOC. In five of 157 patients who underwent IOC, endoscopic retrograde cholangiopancreatography or laparoscopic CBD exploration showed no evidence of CBD stones. In the MRCP group, the rate of retained CBD stones was 0.45 % without MRCP. No patients with normal MRCP findings returned with symptomatic CBD stones during 1-year follow-up. The rate of BDIs was 0.20 % in the IOC group and 0.13 % in the MRCP group.

Conclusions

Selective use of preoperative MRCP is an effective and safe strategy when conducting elective LC to treat gallstones. LC resorting to preoperative MRCP can be performed safely without IOC, with an acceptable rate of retained CBD stones and BDIs.

Who experiences endoscopic retrograde cholangiopancreatography after laparoscopic cholecystectomy for symptomatic gallstone disease?

Purpose

Laparoscopic cholecystectomy (LC) has become a standard treatment of symptomatic gallstone disease. But, some patients suffer from retained common bile duct stones after LC. The aim of this study is to analyze the predicting factors associated with subsequent postoperative endoscopic retrograde cholangiopancreatography (ERCP) after LC.

Methods

We retrospectively reviewed a database of every LC performed between July 2006 and September 2012. We classify 28 patients who underwent ERCP within 6 months after LC for symptomatic gallstone disease as the ERCP group and 56 patients who underwent LC for symptomatic gallstone disease during same period paired by sex, age, underlying disease, operation history, and body mass index as the control group. To identify risk factor performing postoperative ERCP after LC, we compared admission route, preoperative biochemical liver function test, number of gall stones, gallstone size, adhesion around GB, wall thickening of GB, and existence of acute cholecystitis between the 2 groups.

Results

Admission route, preoperative AST, ALT, and ALP, stone size, longer operation time, and acute cholecystitis were identified as risk factors of postoperative ERCP in univariate analyses. But, longer operation time (P = 0.004) and acute cholecystitis (P = 0.048) were identified as independent risk factors of postoperative ERCP in multivariate analyses.

Conclusion

The patient who underwent ERCP after LC for symptomatic gallstone disease are more likely experienced longer operation time and acute cholecystitis than the patient who did not undergo ERCP after LC.

Difficult situations in laparoscopic cholecystectomy: a multicentric retrospective study

INTRODUCTION

Difficult laparoscopic cholecystectomy (LC) is the most common "difficult" surgical procedure performed today, which possesses the potential to place the patient at significant operative risk. We present our retrospective study and experience of 8347 patients with LC since June 1995 to December 2011 at 2 large centers: Mariampur and GSVM Medical College, LLR Hospital, Kanpur, with discussions regarding the practical aspects of LC in difficult situations with respect to conversion to open cholecystectomy.

METHODS

A retrospective analysis of patients who underwent LC from June 1995 to December 2011 was performed. The analysis was performed in relation to the need for conversion and the factors responsible for conversion.

RESULTS

Out of 8347 cases, 2187 cases (26.2%) were identified as difficult. LC was performed successfully in 8265 cases (total completion rate, 99.02%). Of the 2187 difficult cases, LC was completed successfully in 2105 cases (completion rate in difficult cases, 96.25%) and converted to open cholecystectomy in 82 cases (conversion rate in difficult cases, 3.75%).

CONCLUSIONS

Because of the increasing exposure and expertise of surgeons dealing with complex gall bladder laparoscopies, rates of conversion to open cholecystectomy are decreasing and many difficult cases are now handled laparoscopically. However, if required, conversion should not be considered as a failure for the benefit of the patient.

The cooperation between endoscopists and surgeons in treating complications of bariatric surgery

The results of lifestyle interventions and pharmacotherapy are disappointing in severe obesity which is characterised by premature death and many obesity-associated co-morbidities. Only surgery may achieve significant and durable weight losses associated with increased life expectancy and improvement of co-morbidities. Bariatric surgery involves the gastrointestinal tract and may therefore increase gastrointestinal complaints. Bariatric surgery may also result in complications which in many cases can be solved by endoscopic interventions. This requires a close cooperation between surgeons and endoscopists. This chapter will concentrate on the most commonly performed operations such as the Roux-en-Y gastric bypass, the adjustable gastric banding and the sleeve gastrectomy, in the majority of cases performed by laparoscopy. Operations such as the vertical banded gastroplasty and the biliopancreatic diversion with or without duodenal switch will not be discussed at length as patients with these operations will not be encountered frequently and their management can be found under the headings of the other operations.

Patient outcomes after treatment with percutaneous cholecystostomy for biliary sepsis

INTRODUCTION

Acute cholecystitis is among the most common general surgical presentations. There is a cohort of patients who develop systemic sepsis and complications of acute cholecystitis. These patients are often elderly and co-morbid. Conservative management with percutaneous cholecystostomy has been shown to be a safe and effective management option in the acute setting. However, there is currently no consensus for the further management of these patients. In particular, there is a paucity of data on readmission rates and subsequent operative or non-operative management.

METHODS

A retrospective study was carried out of patients treated with a percutaneous cholecystostomy for biliary sepsis over a three-year period in a UK teaching hospital. Outcome measures were subsequent operative or conservative management, conversion rates, operative complications and readmission rates.

RESULTS

Twenty-five patients had a percutaneous cholecystostomy for the treatment of acute biliary sepsis. The median follow-up duration was 35 months. Thirteen patients (52%) had operative treatment. In the operative group, 6/13 had a laparoscopic cholecystectomy, 2/13 had a planned open cholecystectomy, 2/13 had abandoned procedures and 3/13 had a converted procedure. Complications in the operative group included: postoperative mortality (1/13), common bile duct injury requiring drainage and endoscopic stenting (1/13) and one patient required readmission with recurrent pain. In the non-operative group, 5/12 patients were readmitted with biliary sepsis, 5/12 had no readmissions, 1/12 died in the community and 1/12 was readmitted with biliary colic.

CONCLUSIONS

Percutaneous cholecystostomy is a recognised treatment modality for elderly, co-morbid patients with biliary sepsis. Nevertheless, the readmission rate in this group is relatively high at 5/12 (42%). Patients who undergo subsequent operative management have a conversion rate of 3/13 (23%) and a significant complication rate of 2/13 (15%). The further management of patients having undergone percutaneous cholecystostomy requires careful consideration on an individual case basis. The P-POSSUM (Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity) may aid decision making.

Sclerosant foam structure and stability is strongly influenced by liquid air fraction

OBJECTIVES

To determine the effects of sclerosant foam preparation and composition on foam structure, the time course of liquid drainage, and foam coarsening.

METHODS

Sodium tetradecyl sulphate (STS) and polidocanol (POL) foams were investigated in a range of concentrations (0.5-3%) and liquid-plus-air fractions (LAF; 1 + 2 to 1 + 8). Foam was injected into a vein simulation model (polyvinyl chloride tubing, inner diameter 3 mm, constant pressure 5-7 mmHg) filled with saline or blood. Liquid drainage, bubble count, and diameter were measured and documented by serial photography.

RESULTS

Liquid drainage was faster in the vertical position than the horizontal one. In all variations, very small bubbles (diameter <30 μm) were generated initially that coarsened to form micro-foams (<250 μm). By 3 minutes mini-foams (>250 μm) and by 7.5 minutes macro-foams (>500 μm) were formed. Following injection, the upper regions of foam coarsened faster as liquid drained to the bottom of the vessel. Wet preparations produced significantly smaller bubbles. Low concentration POL foam produced significantly higher bubble counts and coarsened slower than STS.

CONCLUSIONS

Foam structure is strongly influenced by the LAF. Despite the initial formation of micro-bubbles in the syringe, mini- and macro-bubbles are formed in target vessels with time post-injection.

Erosions after laparoscopic adjustable gastric banding: diagnosis and management

OBJECTIVE

To define the changing prevalence of erosion after Laparoscopic Adjustable Gastric Banding (LAGB), describing the range of clinical presentations, the approaches to treatment and the outcomes from these approaches over a 15-year study period.

BACKGROUND

A recent systematic review of the literature of erosion after LAGB identified 25 relevant studies and reported a total of 231 erosions in 15,775 patients giving an overall incidence of 1.46%. The review highlighted a broad variation of incidence from 0.2% to 33%. The review was unable to identify either common presentations or an optimal pattern of management.

METHODS

Patients who underwent a primary LAGB operation between September 1994 and January 2010 by 2 surgeons (P.O.B. and W.B.) were identified in a prospectively maintained database. Those patients who had an erosion of their LAGB were identified. Presentation, operative details, demographics, body mass index, weight history, and perioperative problems were analyzed.

RESULTS

In total, 2986 patients were identified. All bands placed were Lap-Bands (Allergan, CA). Hundred erosions were experienced by 85 patients (2.85%) at a median time of 33 months from initial surgery to the erosion (range: 11-170 months). The rate of erosion was highest when the band was placed by the perigastric approach at 6.77%. Since the adoption of the pars flaccida approach, the rate of erosion has dropped to 1.07%. The majority of patients who had experienced an erosion (71 patients; 83.5%) experienced only 1 erosion, 13 patients (15.3%) had 2 erosions, and 1 patient had 3 erosions. The most common presentation was loss of satiety. The band has been successfully replaced in 56 patients. It has been explanted in 27 patients and 2 patients were converted to other bariatric procedures. The weight loss in patients who had a LAGB reinserted after erosion was not significantly different to the background cohort.

CONCLUSIONS

Erosion of LAGB is uncommon and its clinical course is benign. It is best treated with a staged surgical approach; initially, with removal and repair followed later by replacement. With this approach, weight loss is maintained and reerosion is uncommon.

Construction of liver tissue in vivo with preparative partial hepatic irradiation and growth stimulus: investigations of less invasive techniques and progenitor cells

BACKGROUND

The selective proliferation of transplanted hepatocytes with a growth stimulus, such as partial hepatectomy or hepatocyte growth factor, concomitant with hepatic irradiation (HIR), which can suppress proliferation of host hepatocytes, has been reported. We have conducted experiments that focused on less invasive and clinically applicable techniques and progenitor cells.

MATERIALS AND METHODS

First, dipeptidyl-peptidase IV-F344 or jaundiced Gunn rats underwent partial HIR (only 30% of whole liver) and portal vein branch ligation (PVBL) of one lobe, followed by intrasplenic hepatocyte transplantation at 1 × 10(7). Second, after partial HIR and PVBL, two types of progenitor cells were transplanted (i.e., small hepatocytes (SHs) or adipose-derived mesenchymal stem cells.

RESULTS

Sixteen weeks after transplantation, the donor cells constituted > 70% of the hepatocytes of the irradiated lobe, showing connexin 32, phosphoenolpyruvate carboxykinase-1, and glycogen storage. Moreover, the serum bilirubin level had decreased significantly in the jaundiced Gunn rats and remained at this level throughout the 24 wk experimental period. The SHs grew more quickly than the hepatocytes. After 8 wk, around 40% of the host hepatocytes had been replaced by transplanted SHs. Although the donor adipose-derived mesenchymal cells were engrafted after 8 wk, their proliferation was not observed.

CONCLUSIONS

HIR, combined with PVBL, can be given to a selective liver lobe and is a less-invasive but effective method for proliferation of transplanted hepatocytes. Even a smaller number of SHs can construct liver tissue with their prevailing proliferative ability.

Establishment of a stringent large animal model of insulin-dependent diabetes for islet autotransplantation: combination of pancreatectomy and streptozotocin

OBJECTIVE

A stringent porcine islet autograft diabetes model was developed to enable the assessment of autoislet safety and efficacy in either portal vein or an extrahepatic site.

METHODS

A 95% pancreatectomy was performed preserving the pancreaticoduodenal arcade; however, glycemic control was still maintained at 3.3 ± 0.3 days (mean ± SEM), shown by euglycemic fasting blood glucose levels of 4.9 ± 0.8 mmol/L (mean ± SEM, n = 3). To reduce surgical complications and eliminate remaining islets, pigs were dosed intravenously after a modified 90% pancreatectomy, with 150-mg/kg streptozotocin, producing a diabetic state (18.9 ± 1.8 mmol/L [mean ± SEM], n = 8; P < 0.001) within 2.0 ± 0.9 days (mean ± SEM).

RESULTS

Animals presented with sustained hyperglycemia, failing a glucose challenge test 12 weeks after diabetic induction, and showed no stimulated C-peptide secretion compared to nondiabetic controls (baseline: 0.479 ± 0.080 ng/mL [mean ± SEM] vs after procedure: 0.219 ± 0.055 ng/mL [mean ± SEM], P = 0.02). Diabetic animals were maintained on daily insulin. Despite an initial decline in body weight acutely after pancreatectomy and streptozotocin administration, the mean body weight increased after induction over the approximately 88-day study, indicating that the animals were in good health.

CONCLUSION

This stringent porcine model of diabetic induction should be used to assess autograft transplantation safety and efficacy.

Therapeutic liver repopulation for metabolic liver diseases: Advances from bench to bedside

Metabolic liver diseases are characterized by inherited defects in hepatic enzymes or other proteins with metabolic functions. Therapeutic liver repopulation (TLR), an approach of massive liver replacement by transplanted normal hepatocytes, could be used to provide the missing metabolic function elegantly. However, partial and transient correction of the underlying metabolic defects due to very few integrated donor cell mass remains the major obstacle for the effective and widespread use of this approach. Little engraftment and proliferation insufficiency lead to the poor outcome. This article reviews the advances in the mechanisms of initial engraftment and selective proliferation and suggests some effective treatment strategies, from pharmacological preconditioning to stem cell transplantation, to optimize liver repopulation with liver cell transplantation. Enhancing cell viability and plating efficiency, increasing sinusoidal spaces, regulation of sinusoidal endothelial cell barrier and controlling inflammatory reaction may promote initial cell engraftment. Liver-directed irradiation, reversible portal vein embolization and fetal liver stem/progenitor cell transplantation induce preferential proliferation of donor cells substantially without severe side-effects. Furthermore, it seems better to use combined approaches to achieve a high level of liver repopulation for the management of metabolic liver diseases.

Improvement of pig islet function by in vivo pancreatic tissue remodeling: a "human-like" pig islet structure with streptozotocin treatment

Pig islets demonstrate significantly lower insulin secretion after glucose stimulation than human islets (stimulation index of ∼12 vs. 2 for glucose 1 and 15 mM, respectively) due to a major difference in β- and α-cell composition in islets (60% and 25% in humans and 90% and 8% in pigs, respectively). This leads to a lower rise in 3',5'-cyclic adenosine monophosphate (cAMP) in pig β-cells. Since glucagon is the major hormonal effector of cAMP in β-cells, we modified pig islet structure in vivo to increase the proportion of α-cells per islet and to improve insulin secretion. Selected doses (0, 30, 50, 75, and 100 mg/kg) of streptozotocin (STZ) were intravenously injected in 32 young pigs to assess pancreatic (insulin and glucagon) hormone levels, islet remodeling (histomorphometry for α- and β-cell proportions), and insulin and glucagon secretion in isolated islets. Endocrine structure and hormonal content of pig islets were compared with those of human islets. The dose of STZ was significantly correlated with reductions in pancreatic insulin content (p< 0.05, r(2) = 0.77) and the proportion of β-cells (p < 0.05, r(2) = 0.88). A maximum of 50 mg/kg STZ was required for optimal structure remodeling, with an increased proportion of α-cells per islet (26% vs. 48% α-cells per islet for STZ <50 mg/kg vs. >75 mg/kg; p < 0.05) without β-cell dysfunction. Three months after STZ treatment (30/50 mg/kg STZ), pig islets were isolated and compared with isolated control islets (0 mg/kg STZ). Isolated islets from STZ-treated (30/50 mg/kg) pigs had a higher proportion of α-cells than those from control animals (32.0% vs. 9.6%, respectively, p < 0.05). After in vitro stimulation, isolated islets from STZ-treated pigs demonstrated significantly higher glucagon content (65.4 vs. 21.0 ng/ml, p < 0.05) and insulin release (144 µU/ml) than nontreated islets (59 µU/ml, p < 0.05), respectively. Low-dose STZ (<50 mg/kg) can modify the structure of pig islets in vivo and improve insulin secretion after isolation.

Hepatocyte transplantation for inherited metabolic diseases of the liver

Inherited metabolic diseases of the liver are characterized by deficiency of a hepatic enzyme or protein often resulting in life-threatening disease. The remaining liver function is usually normal. For most patients, treatment consists of supportive therapy, and the only curative option is liver transplantation. Hepatocyte transplantation is a promising therapy for patients with inherited metabolic liver diseases, which offers a less invasive and fully reversible approach. Procedure-related complications are rare. Here, we review the experience of hepatocyte transplantation for metabolic liver diseases and discuss the major obstacles that need to be overcome to establish hepatocyte transplantation as a reliable treatment option in the clinic.

Randomized controlled trial comparing three methods of liver retraction in laparoscopic Roux-en-Y gastric bypass

BACKGROUND

This study aimed to evaluate differences between three methods of liver retraction during laparoscopic Roux-en-Y Gastric bypass (LRYGB) and to compare novel liver retraction techniques with the traditional mechanical liver retractor in a randomized controlled trial.

METHODS

In this study, 60 obese patients (26 males and 34 females) who underwent LRYGB between January and July 2010 were randomized to one of three groups (20 in each): group 1 (Nathanson liver retractor), group 2 (liver suspension tape), and group 3 (V-shaped liver suspension technique [V-LIST]). Data regarding demographics (age, sex, body mass index); liver function test (LFT) just before surgery; postoperative results immediately, then 18 h, 1 week, and 1 month after surgery; operative data, and visual analog scale (VAS) for pain on postoperative days (PODs) 1 and 2 were calculated and analyzed.

RESULTS

The groups did not differ significantly in terms of preoperative LFT or operative data except that group 3 took significantly longer time for liver suspension than group 1 (p = 0.01) or group 2 (p = 0.03). The VAS score in group 2 was significantly lower on POD 1 than in group 1 (p = 0.04). Group 1 showed a significant rise in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) at 18 h compared with group 2 (p < 0.01 and p = 0.02, respectively) and group 3 (p < 0.01 and p = 0.01), at 1 week compared with group 2 (p = 0.04 and 0.04), and in AST levels alone during the immediate postoperative compared with group 3 (p = 0.04).

CONCLUSION

The Nathanson liver retractor causes more liver dysfunction than V-LIST or the liver suspension technique and causes more postoperative pain than the liver suspension technique. Both V-LIST and liver suspension tape have a short learning curve and implications for single-port surgery.

Safety assessment of intraportal liver cell application in New Zealand white rabbits under GLP conditions

Liver cell transplantation (LCT) is considered a new therapeutic strategy for the treatment of acute liver failure and inborn metabolic defects of the liver. Although minimally invasive, known safety risks of the method include portal vein thrombosis and pulmonary embolism. Since no systematic data on these potential side effects exist, we investigated the toxicological profile of repeated intraportal infusion of allogeneic liver cells in 30 rabbits under GLP conditions. Rabbit liver cells were administered once daily for 6 consecutive days at 3 different dose levels, followed by a 2-week recovery period. No test item-related mortality was observed. During cell infusion, clinical findings such as signs of apathy and hyperventilation, moderate elevations of liver enzymes ALT and AST and a slight decrease in AP were observed, all fully reversible. Cell therapy-related macroscopic and histological findings, especially in liver and lungs, were observed in animals of all dose groups. In conclusion, the liver and lungs were identified as potential toxicological target organs of intraportal allogeneic liver cell infusion. A NOAEL (no observed adverse effect level) was not defined because of findings observed also in the low-dose group. No unexpected reactions became apparent in this GLP study. Overall, LCT at total doses up to 12 % (2 % daily over 6 days) of the total liver cell count were tolerated in rabbits. Observed adverse effects are not considered critical for treatment in the intended patient populations provided that a thorough monitoring of safety relevant parameters is in place during the application procedure.

Is fixation during gastric banding necessary? A randomised clinical study

Anterior fixation via a gastro-gastric suture in laparoscopic adjustable gastric banding (LAGB) is commonly performed to prevent band-related complications. However, the necessity of this common technique has never been proven. Not fixing the band would be time sparing and would reduce adhesions on the stomach and probably make revisional surgery easier. This study was conceived as a 3-year randomised clinical trial to test the safety and efficacy of the non-fixation technique. From December 2006 to December 2007, 81 patients undergoing LAGB were randomly distributed into two groups: group A, with gastro-gastric sutures (n = 41) and group B, without gastro-gastric fixation (n = 40). The two groups were equivalent regarding initial body mass index (BMI), age and sex ratio. The main outcome was postoperative complications and secondary outcomes were operative time and weight loss expressed by the percentage of excess BMI loss (%EBMIL). All patients were prospectively followed up for 2 years. The mean preoperative BMI was 42.5 kg/m² (35-56). All patients were available for follow-up at 2 years. The mean overall preoperative time was 82 ± 20 min for the fixation group and 72 ± 20 min for the non-fixation group (p = 0.13). The mean hospital stay was 4.1 ± 1.5 days (no significant difference between the two groups). The 2-year %EBMIL was 35.9 for group A and 39.4 for group B (p = NS). The mean BMI at 2 years was 36.3 and 36.1, respectively, with no statistical difference. We observed three early band slippages in the non-fixation group and none in the fixation group. Three bands were removed during the second year of follow-up for causes other than band slippage (no significant difference between the two groups). This study was interrupted before a statistical significance could be reached, under the general agreement of all participating surgeons, because of the three unexpected early band slippages. For the patients who did not suffer from this complication, we did not observe any differences between the two groups in terms of late complications and weight loss. The operative time was shorter in the non-fixation group. This randomised clinical trial suggests that care should be taken when not fixating the LAGB because of the risk of early postoperative band slippage. We suggest that fixing the LAGB by gastro-gastric sutures should remain common practice.

Goettingen Minipigs (GMP): Comparison of Two Different Models for Inducing Diabetes

PURPOSE

Preclinical experiments on large animals are indispensable for evaluating the effectiveness of diabetes therapies. Miniature swine are well suited for such studies due to their physiological and pathophysiological responses.

METHODS

We compare two methods for inducing diabetes in Goettingen minipigs (GMP), in five with the beta cell toxin streptozotocin (STZ) and in five other GMP by total pancreatectomy (PE). Glucose homeostasis was assessed with the intravenous glucose-tolerance test (IVGTT) and continual monitoring of interstitial glucose levels. At conclusion of the observation period, the pancreata were examined histologically. Three non-diabetic GMP served as control group.

RESULTS

The IVGTT revealed markedly diabetic profiles in both GMP groups. STZ-GMP were found to harbor residual C-peptides and scattered insulin-positive cells in the pancreas. PE-GMP survived the total pancreatectomy only with intensive postoperative care.

CONCLUSIONS

Although both methods reliably induced diabetes in GMP, the PE-GMP clearly had more health problems and required a greater expenditure of time and resources. The PE-GMP model, however, was better at eliminating endogenous insulin and C-peptide than the STZ-GMP model.

Partial hepatectomy improves the outcome of intraportal islet transplantation by promoting revascularization

Revascularization of grafts is one of the important key factors for the success of islet transplantation. After partial hepatectomy, many growth factors such as hepatocyte growth factor and vascular endothelial growth factor are increased in the remnant liver. These growth factors have properties that promote angiogenesis. This might be an optimal environment for revascularization of islets transplanted intraportally. To verify this hypothesis, syngeneic islets (330 per recipient) were transplanted into the right hepatic lobes of streptozotocin-induced diabetic Balb/c mice with (hepatectomy group) or without (control group) left liver resection. Blood glucose was monitored for 28 d after transplantation. Glucose tolerance test was performed on post-operative day (POD) 30, and histological assessments were performed on POD 7 and 30 respectively. Analysis revealed that 36.7% of the control and 90.0% of the hepatectomy mice attained normoglycemia during the observation period (*p = 0.0142). Glucose tolerance was improved in the hepatectomy group (Area under the curve of intraperitoneal glucose tolerance tests on POD 30, Control; 47,700 ± 5,890 min*mg/dl, Hepatectomy; 26,000 ± 2,060 min*mg/dl: **p = 0.00314). Revascularization of grafted islets was more pronounced in the hepatectomy group (Vessel number per islet area on POD 7, Control; 3.20 ± 0.463 × 10 (-4) /µm ( 2) , Hepatectomy; 7.08 ± 0.513 × 10 (-4) /µm ( 2) : **p < 0.01). In the present study, partial hepatectomy (30%) improved the outcome of intraportal islet transplantation. Revascularization of islets transplanted into the liver may have been promoted by the induction of liver regeneration.

Clinical uses of liver stem cells

Liver transplantation offers a definitive cure for many liver and metabolic diseases. However, the complex invasive procedure and paucity of donor liver graft organs limit its clinical applicability. Liver stem cells provide a potentially limitless source of cells that would be useful for a variety of clinical applications. These stem cells or hepatocytes generated from them can be used in cellular transplantation, bioartificial liver devices and drug testing in the development of new drugs. In this chapter, we review the technical aspects of clinical applications of liver stem cells and the progress made to date in the clinical setting. The difficulties and challenges of realizing the potential of these cells are discussed.

Systematic review of intraoperative cholangiography in cholecystectomy

BACKGROUND

Intraoperative cholangiography (IOC) is used to detect choledocholithiasis and identify or prevent bile duct injury. The aim of this study was systematically to review the randomized clinical trials of IOC for these two indications.

METHODS

MEDLINE, Embase, the Cochrane Library, clinicaltrials.gov and the World Health Organization database of clinical trials were searched systematically (January 1980 to February 2011) to identify trials. Two authors performed the literature search and extracted data independently. Primary endpoints were bile duct injury and retained common bile duct (CBD) stones diagnosed at any stage after surgery. Preliminary meta-analysis was undertaken, but the trials were too methodologically heterogeneous and the outcome events too infrequent to allow meaningful meta-analysis.

RESULTS

Eight randomized trials were identified including 1715 patients. Six trials assessed the value of routine IOC in patients at low risk of choledocholithiasis. Two trials randomized all patients (including those at high risk) to routine or selective IOC. Two cases of major bile duct injury were reported, and 13 of retained CBD stones. No trial demonstrated a benefit in detecting CBD stones. IOC added a mean of 16 min to the total operating time.

CONCLUSION

There is no robust evidence to support or abandon the use of IOC to prevent retained CBD stones or bile duct injury. Level 1 evidence for IOC is of poor to moderate quality. None of the trials, alone or in combination, was sufficiently powered to demonstrate a benefit of IOC. Further small trials cannot be recommended.

Pig-to-nonhuman primates pancreatic islet xenotransplantation: an overview

The therapy of type 1 diabetes is an open challenging problem. The restoration of normoglycemia and insulin independence in immunosuppressed type 1 diabetic recipients of islet allotransplantation has shown the potential of a cell-based diabetes therapy. Even if successful, this approach poses a problem of scarce tissue supply. Xenotransplantation can be the answer to this limited donor availability and, among possible candidate tissues for xenotransplantation, porcine islets are the closest to a future clinical application. Xenotransplantation, with pigs as donors, offers the possibility of using healthy, living, and genetically modified islets from pathogen-free animals available in unlimited number of islets. Several studies in the pig-to-nonhuman primate model demonstrated the feasibility of successful preclinical islet xenotransplantation and have provided insights into the critical events and possible mechanisms of immune recognition and rejection of xenogeneic islet grafts. Particularly promising results in the achievement of prolonged insulin independence were obtained with newly developed, genetically modified pigs islets able to produce immunoregulatory products, using different implantation sites, and new immunotherapeutic strategies. Nonetheless, further efforts are needed to generate additional safety and efficacy data in nonhuman primate models to safely translate these findings into the clinic.

Hepatocyte transplantation

Hepatocyte transplantation (HTx) has been developed for use in liver-based metabolic disorders and in acute liver failure. Worldwide, there are around 80 patients that have been transplanted with hepatocytes. Almost all reported studies prove feasibility and safety of the procedure with short- to medium-term success. Availability of good quality hepatocytes (HCs) is the main limiting factor, and therefore alternative sources of cells such as stem cells are being investigated. Other limiting factors include cell engraftment, survival, and function of transplanted cells. It remains to be seen if progress in HTx research can overcome these hurdles leading to the wider use of the technique as an alternative to liver transplantation in the future.

A novel technique for liver retraction in laparoscopic bariatric surgery

During bariatric surgery in morbidly obese patients, the surgeon's operative view is often obscured by the hypertrophic fatty left lobe of the liver. The use of a conventional liver retractor mandates an additional subxiphoid wound, resulting in pain and scar formation, in addition to the risk of iatrogenic liver injury during retractor insertion. To overcome these limitations, we developed a simple, rapid, and safe technique for liver retraction--V-shaped liver suspension technique (V-LIST)--by using a Penrose drain and laparoscopic stapler. A silicone Penrose drain was inserted into the peritoneal cavity and stapled to the pars condensa of the lesser omentum and parietal peritoneum using a laparoscopic stapler. The left lobe of the liver was retracted by the V-shaped suspension. At the end of the surgery, the drain could be easily removed. In October 2009-February 2010, 14 patients underwent liver retraction with the use of this technique. We performed 12 Roux-en-Y gastric bypasses and 2 sleeve gastrectomies. This series also included three cases of single incision transumbilical laparoscopic surgery. The mean time required to complete the liver retraction was 8 min 21 s (range, 2-18 min 40 s). Retraction was appropriate in all patients, without the need for additional retractors or conversion. There were no V-LIST-related perioperative complications. Our V-LIST technique using a Penrose drain is safe and simple. It has potential applications in single incision laparoscopic bariatric procedures.

Development of bilateral chylothorax in a younger female secondary to tuberculosis

Chylothorax is a rare clinical entity characterized by a milky white aspirate with increased triglyceride levels. The commonest etiology is malignancy and trauma, and bilateral chylothorax, secondary to tuberculosis, is an extremely rare cause, as observed in the present case.

Major biliary complications in 2,714 cases of laparoscopic cholecystectomy without intraoperative cholangiography: a multicenter retrospective study

BACKGROUND

The ongoing debate between routine and selective users of intraoperative cholangiography (IOC) during laparoscopic cholecystectomy (LC) has not yet come to an end. Routine users argue that IOC decreases the rate of biliary complications such as bile duct injury, biliary leak and missed common bile duct (CBD) stones, a claim that selective users do not fully support. On the other hand, a third policy that was adopted by many other centers is performing LC without IOC. In this retrospective study, we are exploring the results of a relatively large multicenter series of LC without IOC regarding major biliary complications.

METHODS

We performed a retrospective analysis of LC cases operated by experienced laparoscopic surgeons, without resorting to IOC, in four surgical units of university hospitals in Egypt during a 6-year period (January 2004 through December 2009). Excluded from the study were cases with positive predictors of CBD stones, namely, sonographically detected CBD dilatation and/or CBD stones, elevated bilirubin and/or alkaline phosphatase, persistent biliary pancreatitis, cholangitis, and those who had preoperative magnetic resonance cholangiography.

RESULTS

Of the 2,955 cases of LC reviewed, 241 were excluded, leaving 2,714 cases enrolled in the study. Fifty-five cases (2%) were converted to open surgery. Five cases (0.18%) had major bile duct injuries requiring surgical repair. Postoperative bile leakage was encountered in seven cases (0.26%). Missed CBD stones were reported in six cases (0.22%). There was no perioperative mortality in the present study.

CONCLUSION

LC can be performed safely without the use of IOC, with acceptable low rates of biliary complications provided that proper detection of patients with silent CBD stones is done and facilities for pre- and postoperative endoscopic retrograde cholangiopancreatography are available.

A case of a traumatic chyle leak following an acute thoracic spine injury: successful resolution with strict dietary manipulation

Background

Chylothorax is a rare form of pleural effusion that can be associated with both traumatic and non-traumatic causes. Thoracic duct ligation is often the treatment of choice in postsurgical patients; however the optimal treatment of this disease process after traumatic injury remains unclear [1]. We present a rare case of a thoracic duct injury secondary to a blunt thoracic spine fracture and subluxation which was successfully treated non-operatively.

Case Presentation

A 51 year old male presented as a tier one trauma code due to an automobile versus bicycle collision. His examination and radiographic work-up revealed fractures and a subluxation at the third and fourth thoracic spine levels resulting in paraplegia. He also sustained bilateral hemothoraces secondary to multiple rib fractures. Drainage of the left hemothorax led to the diagnosis of a traumatic chylothorax. The thoracic spine fractures were addressed with surgical stabilization and the chylothorax was successfully treated with drainage and dietary manipulation.

Conclusions

This unusual and complex blunt thoracic duct injury required a multidisciplinary approach. Although the spine injury required surgical fixation, successful resolution of the chyle leak was achieved without surgical intervention.

Regional Transient Portal Ischemia and Irradiation as Preparative Regimen for Hepatocyte Transplantation

Hepatocyte transplantation is regarded as a promising option to correct hereditary metabolic liver disease. This study describes a novel method involving regional transient portal ischemia (RTPI) in combination with hepatic irradiation (IR) as a preparative regimen for hepatocyte transplantation. The right lobules of rat livers (45% of liver mass) were subjected to RTPI of 30–120 min. Liver specimens and serum samples were analyzed for transaminase levels, DNA damage, apoptosis, and proliferation. Repopulation experiments involved livers of dipeptidylpeptidase IV (DPPIV)-deficient rats preconditioned with RTPI (60–90 min) either with or without prior partial hepatic IR (25 Gy). After reperfusion intervals of 1 and 24 h, 12 million wild-type (DPPIV positive) hepatocytes were transplanted into recipient livers via the spleen. RTPI of 60–90 min caused limited hepatic injury through necrosis and induced a distinct regenerative response in the host liver. Twelve weeks following transplantation, small clusters of donor hepatocytes were detected within the portal areas. Quantitative analysis revealed limited engraftment of 0.79% to 2.95%, whereas control animals (sham OP) exhibited 4.16% (determined as relative activity of DPPIV when compared to wild-type liver). Repopulation was significantly enhanced (21.43%) when IR was performed prior to RTPI, optimum preconditioning settings being 90 min of ischemia and 1 h of reperfusion before transplantation. We demonstrate that RTPI alone is disadvantageous to donor cell engraftment, whereas the combination of IR with RTPI comprises an effective preparative regimen for liver repopulation. The method described clearly has potential for clinical application.

Competitive edge of laparoscopic appendectomy versus open appendectomy: a subgroup comparison analysis

BACKGROUND

With the advances in laparoscopic instruments and surgical techniques, the use of laparoscopic appendectomy (LA) has been increasing rapidly in recent years. In this retrospective analysis, we aimed to determine the competitive edge of LA versus open appendectomy (OA) in different settings of disease complexity, gender, and age difference.

METHODS

A retrospective analysis of the patients diagnosed with acute appendicitis at Changhua and Chang-Bing Show-Chwan Memorial Hospitals from January 1, 2004 to December 31, 2009 was conducted. Trend and indication of OA and LA were recorded, combined with a comparison of medical costs, complication rates, wound infection rates, and hospital stays in different settings of disease complexity, gender, and age group.

RESULTS

A total of 1366 appendicitis patients were enrolled, and the rate of LA use increased rapidly, from 8.1% in 2004 to 90.3% in 2009. The increased use of LA was seen in both the uncomplicated and complicated appendicitis patients and in both gender and age groups (pediatric, adult, and elderly). Compared with OA, LA was associated with a lower complication rate (9.5% versus 5.8%; P = .013), a lower wound infection rate (8.6% versus 4.2%; P = .001), and a shorter hospital stay (4.60 ± 3.64 versus 4.06 ± 1.84 days; P = .001), but a higher mean cost (32,670 ± 28,568 versus 37,567 ± 12,064 New Taiwan dollars). In the subgroup analysis, the patients with complicated appendicitis, female patients, and pediatric and elderly patients benefited from a reduced hospital stay. LA is about 15% more expensive than OA.

CONCLUSIONS

LA is as safe and effective as OA in many settings of appendicitis and may be selectively advantageous in patients with complicated appendicitis and in elderly subgroups.

The surgical management of obesity with emphasis on the role of post operative imaging

The role of surgery in the morbidly obese is becoming more prominent. There are a variety of surgical approaches which can be used and radiology plays a crucial role in post operative follow up, particularly in the management of complications. Many general radiologists remain unfamiliar with both the normal and abnormal appearances after bariatric surgery and this pictorial review aims to bridge this gap.