Proposed safe apnea test using positive end-expiratory pressure valve and short-term blood gas analysis: Observational study

The apnea test is an essential examination for the determination of brain death; however, hypotension, hypoxemia, and other complications during the apnea test can affect the stability of brain-dead patients, as well as organ function for recipients. Therefore, it is necessary to establish standard guidelines for apnea testing.The modified apnea test (MAT) comprises delivery of 100% oxygen through the endotracheal tube connected to manual resuscitator (Ambu bag) with the positive end-expiratory pressure (PEEP) valve after disconnection of the mechanical ventilator for maintenance of PEEP. Forty-nine instances of the conventional apnea test (CAT) were performed in 25 brain-dead patients; 77 instances of the MAT were performed in 39 brain-dead patients.The mean duration of the apnea test was 3.5 ± 1.4 minutes in the CAT group and 3.0 ± 1.2 minutes in the MAT group. There were no significant changes in PaCO2, PaO2, or pH between the CAT and MAT groups (P = .341, .593, and .503, respectively). In overweight patients (body mass index ≥ 23 kg/m), MAT prevented dramatic reductions in PaO2 and SaO2 (P < .05 for both). In the patients who had hypoxic brain injury due to hanging, differences in PaO2 and SaO2 in the MAT group were significantly smaller than in the CAT group (P < .05).Although MAT, which was invented to maintain PEEP, was not efficient for all brain-dead patients, it could be helpful in selected patient groups, such as overweight patients or those who had hypoxic injury due to hanging. And clinicians should consider short-term apnea test to avoid unnecessarily prolonged hypoxemia.

Neurocognition and adaptive functioning in a genetic high risk model of schizophrenia

BACKGROUND

Identifying factors that influence the functional outcome is an important goal in schizophrenia research. The 22q11.2 deletion syndrome (22q11DS) is a unique genetic model with high risk (20-25%) for schizophrenia. This study aimed to identify potentially targetable domains of neurocognitive functioning associated with functional outcome in adults with 22q11DS.

METHODS

We used comprehensive neurocognitive test data available for 99 adults with 22q11DS (n = 43 with schizophrenia) and principal component analysis to derive four domains of neurocognition (Verbal Memory, Visual and Logical Memory, Motor Performance, and Executive Performance). We then investigated the association of these neurocognitive domains with adaptive functioning using Vineland Adaptive Behavior Scales data and a linear regression model that accounted for the effects of schizophrenia status and overall intellectual level.

RESULTS

The regression model explained 46.8% of the variance in functional outcome (p &lt; 0.0001). Executive Performance was significantly associated with functional outcome (p = 0.048). Age and schizophrenia were also significant factors. The effects of Executive Performance on functioning did not significantly differ between those with and without psychotic illness.

CONCLUSION

The findings provide the impetus for further studies to examine the potential of directed (early) interventions targeting Executive Performance to improve long-term adaptive functional outcome in individuals with, or at high risk for, schizophrenia. Moreover, the neurocognitive test profiles may benefit caregivers and clinicians by providing insight into the relative strengths and weaknesses of individuals with 22q11DS, with and without psychotic illness.

PEDOT:PSS/Polyacrylamide Nanoweb: Highly Reliable Soft Conductors with Swelling Resistance

According to the recent growth in interest of human-friendly devices, soft conductors, which are conductive materials with an inherent compliance, must have a low electrical strain sensitivity under large deformation conditions, environmental stability in water, and reliability even for complex and repeated deformation, as well as nontoxic characteristics. In this study, we fabricated a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/polyacrylamide nanoweb that satisfies all of the above requirements through a web microstructure with entangled conductive nanofibers. Since the web structure can be deformed through structural alignment, the conductive path is stably maintained during deformation, which makes it highly conductive, electrically stable, and electrically strain insensitive. The tangled nanofibers are composed of PEDOT:PSS as a conductive component and polyacrylamide as a binding material, so it is nontoxic and has the soft properties of the material itself, which can withstand large deformations. Additionally, the material has a good electrical stability against repeated deformation so that the resistance increased by only 13% after a 50% strain was repeated 1000 times. Notably, electrical instabilities such as noise and hysteresis were not evident during the repeated deformations. Finally, the nanoweb has excellent swelling resistance and maintains its mechanical and electrical characteristics in water.

Optimized liquid chromatography-tandem mass spectrometry for Otaplimastat quantification in rat plasma and brain tissue

An optimized liquid chromatography-tandem mass spectrometry method for simple and sensitive quantification of Otaplimastat in rat plasma and brain tissue was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation method based on recovery and matrix effect. The chromatographic separation of the sample was performed on a reverse-phase AQ column with an isocratic mobile phase consisting of 10 mM ammonium acetate (pH 4.0) and acetonitrile (50:50, v/v). The analyte was quantified by multiple reaction monitoring with a Waters Quattro micro™ API mass spectrometer. The lower limits of quantification were 20 ng/mL in plasma and 2 ng/g in brain, with the relative standard deviation % of 7.6 and 8.0% for plasma and brain samples, respectively. Acceptable intra-day and inter-day precisions and accuracies were obtained. Otaplimastat was sufficiently stable under all relevant analytical conditions, including a temperature of 4°C for 24 hr, room temperature 20°C for 24 hr, -80°C for 10 days and three freeze-thaw cycles (each at -80°C for 24 hr), for rat plasma and brain tissue. The validated method was successfully used to measure Otaplimastat concentrations in rat plasma and brain samples.

Validation of the eighth edition of the American Joint Committee on Cancer staging system and proposal of an improved staging system for pancreatic ductal adenocarcinoma

Backgrounds/Aims

This study aimed to validate the eighth edition of the American Joint Committee on Cancer (AJCC) staging system for pancreatic adenocarcinoma and to propose an improved staging system for this disease.

Methods

Between 2000 and 2014, 1656 patients underwent surgical resection for pancreatic ductal adenocarcinoma at Asan Medical Center, Seoul, South Korea. The 1169 patients included in this study were recategorized according to the eighth edition of the AJCC staging system. Patients were also categorized according to a new staging system, based on tumor size and number of metastatic lymph nodes.

Results

The seventh edition of the AJCC staging system categorized 93.7% of patients as having stage T3 tumors. Stages were distributed more evenly with the eighth edition. In the N0 group, classification according to the seventh edition showed no statistically significant differences in survival rate between patients with T1 and T2 (p=0.717) and with IA and IB (p=0.717) tumors. Survival rates classified according to the eighth edition differed significantly for all pairs of T stages (p<0.05). With both editions, N stages showed statistically significant differences (p<0.05). Reanalysis showed that a staging system using a tumor size ≥3 cm and ≥1 metastatic lymph nodes was more predictive of survival rates.

Conclusions

Compared with the seventh edition, the eighth edition of the AJCC staging system for pancreatic adenocarcinoma showed a more even distribution in T stage but marginal differences in other stages. The proposed system, using tumor size and number of metastatic lymph nodes, was better at predicting survival.

Validation and Verification of Three-dimensional Systems in Laparoscopic Distal Pancreatectomy

AIM

The three-dimensional (3D) visualization system has been introduced for the technical improvement of laparoscopic surgery, but clinical evidence for its usefulness is lacking. This study aimed to evaluate the usefulness of a 3D system in laparoscopic surgery.

PATIENTS AND METHODS

Between 2015 and 2016, a randomized controlled trial was performed on 61 patients who underwent laparoscopic distal pancreatectomy. The primary outcome was the shortening of operative time. The hospital course, number of technical errors, and clinicians' subjective scores were compared as secondary outcome.

RESULTS

There were no significant differences in operative times, hospital course and technical errors. However, depth perception was significantly improved and physical demand was reduced in the 3D group. These advantages became clearer in the later period of the study, with longer operative times, and in spleen-preserving procedures.

CONCLUSION

Subjective scoring through 3D systems was significantly superior, which might lead to better surgical performance in difficult cases.

Clinicopathologic Characteristics and Optimal Surgical Treatment of Duodenal Gastrointestinal Stromal Tumor

BACKGROUND

The clinicopathologic characteristics of duodenal gastrointestinal stromal tumor (GIST) were unclear and the optimal surgical procedure for duodenal GIST remains poorly defined. We aimed to analyze clinicopathological characteristics, survival outcomes based on the surgical procedure, and recommend optimal surgical treatment for duodenal GIST.

METHODS

From July 2000 to April 2017, 118 patients with localized duodenal GIST underwent curative surgical resection at a single institution. We retrospectively reviewed the clinicopathological characteristics and survival outcomes.

RESULTS

The 5-year overall survival (OS) and disease-free survival (DFS) rates were 94.9 and 79.2%, respectively. On multivariate analysis, the mitotic count was a statistically significant prognostic factor for DFS. Limited resection (LR) was performed in 20 patients with GIST in the first or fourth portion of the duodenum. Both LR and pancreaticoduodenectomy (PD) were performed in 98 patients with GIST in second or third portion of the duodenum. The patients in the LR group had less late complications than in the PD group and no postoperative newly developed diabetes mellitus. The minimally invasive LR (MI-LR) group had a shorter duration of surgery and shorter length of postoperative hospital stay.

CONCLUSION

LR is a feasible and effective surgical treatment for patients with small-sized and antimesenteric-sided duodenal GIST in terms of late complications and postoperative diabetic complications. MI-LR has better perioperative outcomes than open LR. Therefore, we should consider MI-LR as an optimal surgical treatment for selected patients with duodenal GIST.

Impact of preoperative management in patients older than 80 years requiring cholecystectomy

Backgrounds/Aims

Elderly patients aged >80 yr have high morbidity and mortality rates after biliary surgery, especially in emergency operations. We conducted this study to determine the effect of preoperative management on the outcome of elderly patients undergoing cholecystectomy.

Methods

The medical records of 452 elderly (≥80 yr old) patients who underwent cholecystectomy from January 1997 to December 2015 were reviewed retrospectively. We divided the patients into 2 groups: intervention (preoperative biliary drainage) and non-intervention groups. We evaluated the effects of preoperative management on the American Society of Anesthesiology (ASA) score and perioperative outcomes.

Results

Among the preoperative biliary drainage intervention group (n=286), 48 patients (51.7%) were diagnosed as having gallbladder stone combined with common bile duct stone. On admission, the proportion of patients with ASA score ≥3 and WBC counts were significantly higher in the intervention group than in the non-intervention group (p<0.05). The preoperative hospital stay was longer in the intervention group; however, operation-related factors such as operation type, time, conversion rate, complications, and mortality showed no difference between groups.

Conclusions

With proper preoperative evaluations and preoperative biliary drainage, cholecystectomy can be a safe treatment option for elderly patients with cholelithiasis.

A Single-Center Experience with an Intensivist-Led Brain-Dead Donor Management Program

Background

The aim of this study is to report our experience of brain-dead donor management by a dedicated intensivist who had wide experience in treatment of hemodynamically unstable patient and to suggest a role for intensivists in organ donation.

Material/Methods

The management of brain-dead donors was performed by experienced intensivists. The hospital medical records and data from the Korean Network of Organ Sharing from August 2013 to December 2016 were reviewed retrospectively.

Results

Fifty-four brain death patients (3.2% of KONOS nationwide data) donated organs in our institution during 41 months. Dedicated intensivists managed deceased patients for the whole duration (2.81±1.21 days) of management, not only with conservative therapies like fluid resuscitation, vasopressor, or hormonal replacement, but also with pulmonary artery catheter insertion for cardiac output monitoring (n=47, 87.0%) and continuous renal replacement therapy (n=22, 40.7%). The number of donors increased each year. The mean number of retrieved organs in each deceased donor was 3.98±1.55, more than the national average (3.26) and comparable to the higher level among the recent worldwide data. The number of donations by organ was: 23 hearts (4.9% of nationwide data), 17 lungs (7.5% of nationwide data), 102 kidneys (3.3% of nationwide data), 47 livers (3.1% of nationwide data), 6 pancreases (2.9% of nationwide data), 1 pancreatic duct (11.1% of nationwide data), and 1 small intestine (12.5% of nationwide data).

Conclusions

Management by dedicated intensivists will improve not only the number of actual organ donors, but also the number of harvested organs.

Absence of antitumor effects of metformin in sorafenib-treated patients with hepatocellular carcinoma recurrence after hepatic resection and liver transplantation

Backgrounds/Aims

Hepatocellular carcinoma (HCC) recurrence following hepatic resection (HR) and liver transplantation (LT) remains a great concern. We assessed the antitumor effects of metformin in patients treated with sorafenib for HCC recurrence after HR or LT.

Methods

The two clinical retrospective studies involved metformin therapy of 304 HR patients and 74 LT recipients who were treated with sorafenib.

Results

In the study involving patients who had undergone HR, death occurred in 245 of the 304 patients (80.6%) during a median follow-up of 10.2 months after sorafenib administration. The metformin HR group (group 1; n=40) showed no prognostic difference in progression-free and overall survival rates compared with the all-HR control group (group 3; n=241) and propensity score-matched HR control group (group 4; n=80). In the clinical study of recipients exposed to LT, death occurred in 62 of the 74 patients (83.8%) during a median follow-up of 13.6 months (range: 3–76 months) after sorafenib administration. The metformin LT group (group 5; n=14) showed no prognostic difference in progression-free and overall survival rates compared with the all-LT control group (group 7; n=43) and propensity score-matched LT control group (group 8; n=28).

Conclusions

Our clinical studies demonstrated absence of synergistic antitumor effects of metformin. Further high-volume studies are necessary to assess the role of metformin in patients treated with sorafenib for advanced HCC.

The survival impact of surgical waiting time in patients with resectable pancreatic head cancer

Backgrounds/Aims

After centralization policy, clinical outcomes have been improved in patients underwent pancreaticoduodenectomy for pancreatic cancer. However, centralization could exacerbate the prolongation of surgical waiting time. This study aims to investigate whether the shorter waiting time correlates with the better survival and to identify the major confounders that influence the association between those.

Methods

In this retrospective cohort study, a total 554 patients with pathologically confirmed pancreatic ductal adenocarcinoma were assessed the eligibility from 2014 through 2015. Patients with neoadjuvant chemotherapy, body-tail resection, total pancreatectomy and combined adjacent organ resection were excluded. All patients were divided into two groups by median waiting time, 21 days, defined as the date difference between initial imaging diagnosis and operation.

Results

Median overall survival did not differ between long and short waiting group (30.4 vs 24.8 months, p=0.35; HR=0.84, 95% CI=0.58-1.21). The proportion of cancer stage shifting, the difference between clinical and pathologic staging, did not differ depending on waiting time group (p=0.811 and 0.255, each of reviewers). Short waiting time was highly correlated with high initial clinical stage (Spearman correlation coefficients -0.201 (p=0.006) and -0.100 (p=0.175), each of reviewers).

Conclusions

Initial clinical stage had confounding effect on the association between waiting time and overall survival. Therefore, in evaluating centralization policy at the national level, evidence for maximum acceptable waiting time should be investigated in the near future with considering that surgical waiting time could be affected by initial clinical stage.

Validation of the OncoHepa test, a multigene expression profile test, and the tumor marker-volume score to predict postresection outcome in small solitary hepatocellular carcinomas

Purpose

OncoHepa test is a multigene expression profile test developed for assessment of hepatocellular carcinoma (HCC) prognosis. Multiplication of α-FP, des-γ-carboxy prothrombin (DCP) and tumor volume (TV) gives the α-FP-DCP-volume (ADV) score, which is also developed for assessment of HCC prognosis.

Methods

The predictive powers of OncoHepa test and ADV score were validated in 35 patients who underwent curative hepatic resection for naïve solitary HCCs ≤5 cm.

Results

Median tumor diameter was 3.0 cm. Tumor recurrence and patient survival rates were 28.6% and 100% at 1 year, 48.6% and 82.9% at 3 years, and 54.3% and 71.4% at 5 years, respectively. The site of first tumor recurrence was the remnant liver in 18, lung in 1, and the peritoneum in 1. All patients with HCC recurrence received locoregional treatment. OncoHepa test showed marginal prognostic significance for tumor recurrence and patient survival. ADV score at 4log also showed marginal prognostic difference with respect to tumor recurrence and patient survival. Combination of these 2 tests resulted in greater prognostic significance for both tumor recurrence (P = 0.046) and patient survival (P = 0.048).

Conclusion

Both OncoHepa test and ADV score have considerably strong prognostic power, thus individual and combined findings of OncoHepa test and ADV score will be helpful to guide postresection surveillance in patients with solitary HCCs ≤5 cm.

Amniotic fluid index, single deepest pocket and transvaginal cervical length: Parameter of predictive delivery latency in preterm premature rupture of membranes

OBJECTIVE

Prediction of delivery latency complicated with preterm premature rupture of membrane (PPROM) is crucial for reducing maternal and neonatal complications. Therefore, we investigated the correlations between latency period and cut-off values of ultrasonographic parameters, ultimately predicting delivery latency.

MATERIALS AND METHODS

The retrospective study was performed on 121 PPROM patients enrolled between March 2010 and July 2015. Parameters including amniotic fluid index (AFI), single deepest pocket (SDP) and transvaginal cervical length (TVCL) were measured in 99 singleton pregnancies with PPROM. Latency was defined as the period from sonographic measurements to delivery day. The parameters were analyzed independently by Wilcoxon rank sum test and Fisher's exact test. Cut-off values were determined using a receiver operating characteristic (ROC) curve.

RESULTS

In delivery latency within 3 days, AFI and SDP were decreased with significantly shorter TVCL. AFI and SDP had the highest sensitivity (82.2%) and SDP combined with TVCL showed the highest specificity (75.9%) in area under curve (AUC) value. The predicted median latency period was less than 2 days within the cutoff value of parameter (AFI ≤ 7.72, SDP ≤ 3.2 and TVCL ≤ 1.69).

CONCLUSION

AFI and SDP combined with TVCL could be useful predictive parameters of the latency interval from PPROM to delivery.

Prognostic Prediction Models for Resection of Large Hepatocellular Carcinoma: A Korean Multicenter Study

BACKGROUND

We developed a prognostic prediction model (PPM) using 4 factors for hepatic resection (HR) of large hepatic cellular carcinoma (HCC). Multiplication of α-fetoprotein (AFP), des-γ-carboxy prothrombin, and tumor volume (TV) (ADV score) is a surrogate marker for post-resection prognosis. This study intended to validate the predictive power of 4-factor PPM and to develop new ADV score-based PPM.

METHODS

A total of 526 patients who underwent HR for solitary HCC ≥ 8 cm were selected from 9 Korean institutions between 2008 and 2014.

RESULTS

Median tumor diameter and TV were 11.0 cm and 398 mL, respectively. Tumor recurrence and patient survival rates were 53.0 and 78.4% at 1 year and 70.2 and 49.3% at 5 years, respectively. Independent risk factors for both tumor recurrence and patient survival included AFP ≥ 100 ng/mL, hypermetabolic FDG-positron emission tomography (PET), microvascular invasion and satellite nodules, which comprised 4 factors of the PPM. Five subgroups based on the number of involved risk factors exhibited significant differences in tumor recurrence and patient survival. ADV score cutoff was set at 7log (ADV7log) after cluster prognostic analysis. Patient grouping according to combination of ADV7log and FDG-PET findings (ADV7log-PET) exhibited significant differences in tumor recurrence and patient survival, comparable to those of the 4-factor PPM.

CONCLUSIONS

Two PPMs using 4 risk factors and ADV7log-PET could reliably predict the risk of early HCC recurrence and long-term survival outcomes in patients who underwent HR for large HCC. We believe that these PPMs can guide surgical treatment for large HCCs from preoperative HR planning to post-resection follow-up.

Canavalia ensiformis-derived lectin inhibits biofilm formation of enterohemorrhagic Escherichia coli and Listeria monocytogenes

AIM

A lectin Concanavalin A (ConA) derived from Canavalia ensiformis (jack bean) exhibits high-binding affinity to carbohydrates on bacterial cell surfaces. The objective of this study was to inhibit the biofilm formation of the foodborne pathogens enterohemorrhagic Escherichia coli and Listeria monocytogenes using ConA prepared by a membrane-based extraction method.

METHODS AND RESULTS

ConA was extracted using a simple and inexpensive membrane method instead of a chromatography approach. The extracted ConA was effective in inhibiting biofilms of E. coli by 30-fold and L. monocytogenes by 140-fold. In addition, ConA decreased the swimming motility of enterohemorrhagic E. coli EDL933 (EHEC) by 37%, resulting in low biofilm formation, as ConA binding to the bacterial cell surfaces might cause a reduced capability to adhere due to low cellular motility. We confirmed that the extracted ConA contains active components at less than 10 kDa as well as ConA multimers (>30 kDa) that repress EHEC biofilms. Additionally, noncell-based mannose reduced the activity of ConA in inhibiting biofilms.

CONCLUSIONS

ConA extracted using the membrane-based method is active in inhibiting the biofilm formation by E. coli and L. monocytogenes via the mannose-binding affinity of ConA.

SIGNIFICANCE AND IMPACT OF THE STUDY

ConA can be used as a promising anti-adherent and antibiofilm agent in inhibiting biofilm formation by enterohemorrhagic E. coli and L. monocytogenes. The membrane-based extraction approach may be applied for the economic production of biologically active lectins.

Corticotrophin-releasing factor-mediated effects of DA-9701 in Postoperative Ileus Guinea Pig Model

BACKGROUND

Postoperative ileus (POI) is abdominal surgery-induced impaired gastrointestinal (GI) motility. We aimed to investigate the effects of DA-9701, a prokinetic agent formulated from Pharbitis Semen and Corydalis tuber, likely mediated via corticotrophin-releasing factor (CRF) pathways, in a POI model.

METHODS

A laparotomy with cecal manipulation was performed to induce POI in guinea pigs. GI transit was measured based on charcoal migration after intragastric administration of DA-9701 1, 3, and 10 mg kg^-1 . CRF1 receptor antagonist, CP-154 526 (subcutaneous) or agonist, human/rat (h/r) CRF (intraperitoneal) was injected. Then, plasma adrenocorticotropic hormone (ACTH) levels were measured, and the average intensity of the CRF expression was analyzed in the proximal colon and hypothalamus, and c-Fos in the hypothalamus.

KEY RESULTS

DA-9701 significantly increased delayed GI transit in POI in a dose-dependent manner and decreased plasma ACTH levels at 10 mg kg^-1 . CP-154 526 significantly decreased plasma ACTH levels but was not as effective on GI transit as DA-9701 was. h/r CRF did not significantly affect GI transit and plasma ACTH levels. No significant difference was observed in GI transit and plasma ACTH levels in both groups administered DA-9701 with h/r CRF and h/r CRF alone. CRF expression in the proximal colon decreased after DA-9701 administration, but not significantly, compared with levels in POI alone. However, CRF expression in the hypothalamus was significantly lower in the DA-9701-pretreated POI than in the untreated POI.

CONCLUSIONS AND INFERENCES

The DA-9701-induced improvement in GI transit and inhibition of plasma ACTH levels was mediated by the central CRF pathway.

Impact of a Multidisciplinary Team Approach for Managing Advanced and Recurrent Colorectal Cancer

BACKGROUND

The wide variety of treatment strategies makes clinical decision-making difficult in advanced and recurrent colorectal cancer cases. Many hospitals have started multidisciplinary team (MDT) meetings comprising a team of dedicated specialists for discussing cases. MDTs for selected cases that are difficult to diagnose and treat are alternatives to regular MDTs. This study's aim was to determine the impact of a MDT for colorectal cancer on clinical decision-making.

METHODS

Cases were discussed when clinical specialists had difficulty making decisions alone. All processes done by the MDT were then recorded in prospectively designed medical case forms.

RESULTS

From Jan 2011 to Dec 2014, 1383 cases were discussed. A total of 549 (39.8%) case forms were completed for patients with newly diagnosed colorectal cancer, whereas 833 (60.2%) were completed for those with recurrent diseases. The MDT altered the proposed treatment of the referring physician in 179 (13%) cases. In 85 of the 179 (47.5%) altered cases, the radiologist's review of clinical information affected the diagnosis and decision. Furthermore, 152 of the 1383 MDT decisions were not implemented. Treatment intent, therapeutic plan, and alteration of decision were important reasons for not following the MDT's recommendation.

CONCLUSION

Case discussions in MDT meetings resulted in altered clinical decisions in >10% cases. Implementation rates after MDT discussions might be affected by the treatment decision-making process. Imperfect decisions made by individual physicians can be decreased by the multidisciplinary decision-making process.

Wing-wake interaction: comparison of 2D and 3D flapping wings in hover flight

The wing-wake interaction of flapping wings while hovering has been investigated, with the focus on the difference in wing-wake interaction between 2D and 3D flapping wings. Numerical simulations are conducted at a Reynolds number of 100, and the flapping configurations are divided into the 2D, quasi-3D and 3D categories. Variations of the aspect ratio and Rossby number allow the flapping configuration to morph gradually between categories. The wing-wake interaction mechanisms are identified and the effect of three-dimensionality on these mechanisms is discussed. Three-dimensionality affects wing-wake interaction through four primary aerodynamic mechanisms, namely, induced jet, downwash/upwash, leading-edge vortex (LEV) shedding due to vortex pairing, and the formation of a closely attached LEV. The first two mechanisms are well-established in the literature. With regard to the LEV shedding mechanism, it is revealed that the interaction between the LEV and the residue vortex from the previous stroke plays an important role in the early vortex shedding of 2D flapping wings. This effect diminishes with increasing three-dimensionality. With regard to the mechanism of the closely attached LEV, the wake encourages the formation of an LEV that is closely attached to the wing's top surface, which is beneficial to lift generation. This closely attached LEV mechanism accounts for most of the lift enhancement that arises from wake effects. Three-dimensionality alters the efficacy of the different aerodynamic mechanisms. Consequently, the dual peak lift coefficient pattern typically seen on 2D flapping wings transforms into the single peak lift coefficient pattern of the 3D flapping wing. It is also demonstrated that the mean lift enhancement due to wing-wake interaction diminishes rapidly when three-dimensionality is introduced. Results suggest that, for wings with parameters close to those of natural flyers, wing-wake interaction yields marginal lift enhancement and a small increase in energy consumption.

Characteristics and Clinical Outcomes of Critically Ill Cancer Patients Admitted to Korean Intensive Care Units

Background

The objective of this study was to investigate the characteristics and clinical outcomes of critically ill cancer patients admitted to intensive care units (ICUs) in Korea.

Methods

This was a retrospective cohort study that analyzed prospective collected data from the Validation of Simplified Acute Physiology Score 3 (SAPS3) in Korean ICU (VSKI) study, which is a nationwide, multicenter, and prospective study that considered 5,063 patients from 22 ICUs in Korea over a period of 7 months. Among them, patients older than 18 years of age who were diagnosed with solid or hematologic malignancies prior to admission to the ICU were included in the present study.

Results

During the study period, a total of 1,762 cancer patients were admitted to the ICUs and 833 of them were deemed eligible for analysis. Six hundred fifty-eight (79%) had solid tumors and 175 (21%) had hematologic malignancies, respectively. Respiratory problems (30.1%) was the most common reason leading to ICU admission. Patients with hematologic malignancies had higher Sequential Organ Failure Assessment (12 vs. 8, P<0.001) and SAPS3 (71 vs. 69, P<0.001) values and were more likely to be associated with chemotherapy, steroid therapy, and immunocompromised status versus patients with solid tumors. The use of inotropes/vasopressors, mechanical ventilation, and/or continuous renal replacement therapy was more frequently required in hematologic malignancy patients. Mortality rates in the ICU (41.7% vs. 24.6%, P<0.001) and hospital (53.1% vs. 38.6%, P=0.002) were higher in hematologic malignancy patients than in solid tumor patients.

Conclusions

Cancer patients accounted for one-third of all patients admitted to the studied ICUs in Korea. Clinical characteristics were different according to the type of malignancy. Patients with hematologic malignancies had a worse prognosis than did patients with solid tumor.

Transduodenal ampullectomy for ampullary tumors - single center experience of consecutive 26 patients

Purpose

Transduodenal ampullectomy (TDA) has been reported in a limited number of cases and in a small number of case series. The aim of this study was to analyze perioperative and long-term oncological outcomes of patients with ampullary tumors who underwent TDA in a single large-volume center.

Methods

Through a retrospective review of data from 2004 to 2016, we identified 26 patients who underwent TDA at Asan Medical Center.

Results

Eleven of 26 patients underwent TDA for T1 and carcinoma in situ (high-grade dysplasia) cancer; these patients are still alive without recurrence. A major in-hospital complication (3.8%) occurred in 1 case, but there was no case of 90-day mortality. In addition, none of the patients was diagnosed as having newly developed diabetes mellitus after TDA. No significant differences were found between open and laparoscopic-TDA in terms of operation time, painkiller use, and hospital stay.

Conclusion

TDA is a feasible and effective surgical procedure for the treatment of selected patients with ampullary tumors. It is an alternative treatment option in cases of ampullary tumors not amenable to endoscopic papillectomy or pancreaticoduodenectomy.

Prognostic implications of hepatitis B virus infection in intrahepatic cholangiocarcinoma treated with first-line gemcitabine plus cisplatin

PURPOSE:

Hepatitis B virus infection is a well-known risk factor for intrahepatic cholangiocarcinoma. However, its prognostic impact has rarely been investigated in advanced intrahepatic cholangiocarcinoma.

METHODS:

Between April 2010 and May 2015, 296 patients with unresectable or metastatic intrahepatic cholangiocarcinoma who received gemcitabine plus cisplatin (GemCis) were categorized into a hepatitis B virus group (n=62; 21%) and a non-hepatitis B virus group (n=234; 79%). Clinicopathological features and survival outcomes were retrospectively reviewed and analyzed.

RESULTS:

The median age of patients was 59 years (range, 27-78). The median overall survival with first-line GemCis was 9.4 months (95% CI 8.4, 10.4). Compared to the non-hepatitis B virus group, the hepatitis B virus group was younger (median age, 57 vs. 61 years, P = 0.001), mainly male (74% vs. 57%, P = 0.02), and had lower frequency of elevated cancer antigen (CA) 19-9 (34% vs. 59%, P = 0.001) and alkaline phosphatase (43% vs. 61%, P = 0.01). In a univariate analysis, the hepatitis B virus infection showed a marginal relationship with poor overall survival compared to the non-hepatitis B virus infection (median, 8.3 vs. 10.0 months; P=0.13). A multivariate analysis of potential prognostic factors revealed a significant association with poor overall survival in the hepatitis B virus group (hazard ratio (HR) =1.50, P = 0.02). Initial metastatic disease (vs. recurrent/unresectable disease; HR=1.50), metastatic sites ⩾ 2 (vs. 0-1; HR=1.51), Eastern Cooperative Oncology Group performance status ⩾ 2 (vs. 0-1; HR=1.93), elevated total bilirubin (vs. normal; HR=1.83), and low albumin (vs. normal; HR=1.52) were significantly related to an unfavorable overall survival.

CONCLUSIONS:

This study suggests that the hepatitis B virus infection may be associated with distinctive clinicopathological characteristics and poor outcome in advanced intrahepatic cholangiocarcinoma treated with GemCis.