Microbiome engineering: Taming the untractable.

In this issue of Cell, Jin et al. describe several innovative tools for microbiome engineering to enable in situ editing of complex communities. However, challenges remain to overcome the widespread genetic intractability of microbiome constituents.

Toward Microbiome Engineering: Expanding the Repertoire of Genetically Tractable Members of the Human Gut Microbiome.

Genetic manipulation is necessary to interrogate the functions of microbes in their environments, such as the human gut microbiome. Yet, the vast majority of human gut microbiome species are not genetically tractable. Here, we review the hurdles to seizing genetic control of more species. We address the barriers preventing the application of genetic techniques to gut microbes and report on genetic systems currently under development. While methods aimed at genetically transforming many species simultaneously in situ show promise, they are unable to overcome many of the same challenges that exist for individual microbes. Unless a major conceptual breakthrough emerges, the genetic tractability of the microbiome will remain an arduous task. Increasing the list of genetically tractable organisms from the human gut remains one of the highest priorities for microbiome research and will provide the foundation for microbiome engineering.

Bioinformatic analysis of bacteria and host cell dual RNA-sequencing experiments.

Bacterial pathogens subvert host cells by manipulating cellular pathways for survival and replication; in turn, host cells respond to the invading pathogen through cascading changes in gene expression. Deciphering these complex temporal and spatial dynamics to identify novel bacterial virulence factors or host response pathways is crucial for improved diagnostics and therapeutics. Dual RNA sequencing (dRNA-Seq) has recently been developed to simultaneously capture host and bacterial transcriptomes from an infected cell. This approach builds on the high sensitivity and resolution of RNA sequencing technology and is applicable to any bacteria that interact with eukaryotic cells, encompassing parasitic, commensal or mutualistic lifestyles. Several laboratory protocols have been presented that outline the collection, extraction and sequencing of total RNA for dRNA-Seq experiments, but there is relatively little guidance available for the detailed bioinformatic analyses required. This protocol outlines a typical dRNA-Seq experiment, based on a Chlamydia trachomatis-infected host cell, with a detailed description of the necessary bioinformatic analyses with currently available software tools.

Sleep problems in advanced cancer patients and their caregivers: Who is disturbing whom?

Background The aims of the study were to understand sleep problems and their effects in advanced cancer patients and spousal and intimate partner caregivers and to examine the directionality of the link between patients' and caregivers' sleep problems. Methods Fifty-four advanced cancer patients and their spousal and intimate partners were administered a battery of questionnaires that included the Pittsburgh Sleep Quality Index and the Center for Epidemiological Studies at the patients' cancer diagnosis and at 2, 4, and 6 months after diagnosis. Results Patients' and caregivers' sleep duration was significantly related. Using cross-lagged panel analyses, caregivers' sleep quality significantly predicted patients' sleep quality and patients' sleep quality subsequently predicted caregivers' sleep quality. Patients' sleep latency significantly was found to significantly predict caregivers' sleep latency. Conclusion Patients diagnosed with cancer and their intimate partners have poor sleep quality and sleep patterns are related.

Socioeconomic disparities of depressive symptoms and cytokines in hepatocellular carcinoma.

OBJECTIVE: To examine the associations among socioeconomic factors, depressive symptoms, and cytokines in patients diagnosed with hepatocellular carcinoma (HCC). METHODS: A total of 266 patients diagnosed with HCC were administered a battery of questionnaires including a sociodemographic questionnaire and the Center for Epidemiologic StudiesDepression (CES-D) scale. Blood samples were collected to assess serum levels of cytokines using Luminex. Descriptive statistics, Mann-Whitney U, Kruskal-Wallis, linear regression, and Bonferroni corrections were performed to test the hypotheses. RESULTS: Of the 266 patients, 24% reported depressive symptoms in the clinical range (CES-D ≥ 22). Females had higher CES-D score than males (Mann-Whitney U = 7135, P = .014, Padj  = .028). Being unemployed/disabled (Kruskal-Wallis = 14.732, P = .001, Padj  = .005) was found to be associated with higher depressive symptoms in males but not in females. Serum level of IL-2 (Kruskal-Wallis = 17.261, P = .001, Padj  = .005) were found to be negatively associated with education level. Gender (ß = .177, P = .035), income (ß = -.252, P = .004), whether the patient's income met their basic needs (ß = .180, P = .035), and IL-1ß (ß = -.165, P = .045) independently predicted depressive symptoms and together explained 19.4% of variance associated with depressive symptoms. CONCLUSIONS: Sociodemographic and socioeconomic factors were predictive of inflammation and depressive symptoms. Recommendations include the development of gender-targeted interventions for patients diagnosed with HCC who have low socioeconomic status (SES) and may suffer from depressive symptoms.

Structure-activity analysis of peptidic Chlamydia HtrA inhibitors.

Chlamydia trachomatis high temperature requirement A (CtHtrA) is a serine protease that performs proteolytic and chaperone functions in pathogenic Chlamydiae; and is seen as a prospective drug target. This study details the strategies employed in optimizing the irreversible CtHtrA inhibitor JO146 [Boc-Val-Pro-ValP(OPh)2] for potency and selectivity. A series of adaptations both at the warhead and specificity residues P1 and P3 yielded 23 analogues, which were tested in human neutrophil elastase (HNE) and CtHtrA enzyme assays as well as Chlamydia cell culture assays. Trypsin and chymotrypsin inhibition assays were also conducted to measure off-target selectivity. Replacing the phosphonate moiety with α-ketobenzothiazole produced a reversible analogue with considerable CtHtrA inhibition and cell culture activity. Tertiary leucine at P3 (8a) yielded approximately 33-fold increase in CtHtrA inhibitory activity, with an IC50 = 0.68 ±â€¯0.02 µM against HNE, while valine at P1 retained the best anti-chlamydial activity. This study provides a pathway for obtaining clinically relevant inhibitors.

Prospective Analyses of Cytokine Mediation of Sleep and Survival in the Context of Advanced Cancer.

OBJECTIVE: The aims of this study were to examine the potential association between sleep problems, symptom burden, and survival in patients with advanced cancer. METHODS: A prospective study of 294 patients with gastrointestinal cancer administered questionnaires assessing sleep, depression, anxiety, stress, pain, fatigue, and health-related quality of life. Serum levels of cytokines including interleukin (IL)-1α, IL-1ß, tumor necrosis factor α, IL-10, IL-2, and interferon-γ were measured to assess biological mediation between sleep and survival. Survival was measured as time from diagnosis to death. RESULTS: Fifty-nine percent of patients reported poor sleep quality, 53% reported poor sleep efficiency, 39% reported sleep latency greater than 30 minutes, and 45% reported sleeping less than 6 hours or greater than 10 hours. We found a significant association between sleep duration and symptom burden. Shorter sleep duration was significantly associated with higher levels of fatigue (r = -0.169, p = .01), pain (r = -0.302, p = .01), anxiety (r = -0.182, p = .01), depression (r = -0.172, p = .003), and lower levels of quality of life (r = 0.240, p = .01). After adjustment for demographic, psychological, and disease-specific factors, short sleep duration was associated with reduced survival (hazard ratio [HR] linear = 0.485, 95% confidence interval = 0.275-0.857) and there was also evidence for a quadratic pattern (HR quadrati = 1.064, 95% confidence interval = 1.015-1.115) suggesting a curvilinear relationship between sleep duration and survival. Interleukin 2 was the only cytokine significantly related to survival (HR = 1.01, p = .003) and sleep duration (ß = -30.11, p = .027). When of IL-2 was added to the multivariable model, short and long sleep (ß = -0.557, p = .097; ß = 0.046, p = .114) were no longer significantly related to survival, suggesting mediation by IL-2. CONCLUSION: Sleep duration was associated with symptom burden and poorer survival and IL-2 was found to mediate the association between sleep and survival. Screening and treatment of sleep problems in patients diagnosed with cancer are warranted.

Leukaemia mortality and low-dose ionising radiation in the WISMUT uranium miner cohort (1946-2013).

OBJECTIVES: To examine the risk of death from leukaemia in relation to occupational chronic low-level external and internal radiation exposure in a cohort of 58 972 former German uranium miners with mortality follow-up from 1946 to 2013. METHODS: The red bone marrow (RBM) dose from low-linear energy transfer (LET) (mainly external γ-radiation) and high-LET (mainly radon gas) radiation was estimated based on a job-exposure matrix and biokinetic/dosimetric models. Linear excess relative risks (ERR) and 95% CIs were estimated via Poisson regression for chronic lymphatic leukaemia (CLL) and non-CLL. RESULTS: The mean cumulative low-LET and high-LET RBM doses among the 86% radiation-exposed workers were 48 and 9 mGy, respectively. There was a positive non-significant dose-response for mortality from non-CLL (n=120) in relation to low-LET (ERR/Gy=2.18; 95% CI -0.41 to 6.37) and high-LET radiation (ERR/Gy=16.65; 95% -1.13 to 46.75). A statistically significant excess was found for the subgroup chronic myeloid leukaemia (n=31) in relation to low-LET radiation (ERR/Gy=7.20; 95% CI 0.48 to 24.54) and the subgroup myeloid leukaemia (n=99) (ERR/Gy=26.02; 95% CI 2.55 to 68.99) for high-LET radiation. The ERR/Gy tended to be about five to ten times higher for high-LET versus low-LET radiation; however, the CIs largely overlapped. Results indicate no association of death from CLL (n=70) with either type of radiation. CONCLUSIONS: Our findings indicate an increased risk of death for specific subtypes from non-CLL in relation to chronic low-LET and high-LET radiation, but no such relation for CLL.

Longterm survival outcomes of patients undergoing treatment with radiofrequency ablation for hepatocellular carcinoma and metastatic colorectal cancer liver tumors.

BACKGROUND: We aim to investigate long-term survival outcomes in patients undergoing radiofrequency ablation (RFA), based on our longitudinal 5 and 10 year follow-up data. METHODS: All patients who underwent RFA for hepatocellular carcinoma (HCC) and colorectal liver metastasis (CLM) between 1999 and 2010. RESULTS: 320 patients were included with oncologic diagnoses of HCC in 122 (38.1%) and CLM in 198 (61.9%). The majority of patients had a single tumor ablation (71% RFA 1 lesion). Minimum 5 year follow-up information was available in 89% patients, with a median follow-up of 115.3 months. In patients with HCC, disease eventually recurred in 73 (64%) patients. In patients with CLM, disease recurrence was ultimately seen in 143 (84.1%) patients. In the HCC group, the 5- and 10-year overall survivals were 38.5% and 23.4%, while in the CLM group, the 5- and 10-year overall survivals were 27.6% and 15%, respectively. CONCLUSIONS: The use of RFA as a part of treatment strategy for primary and metastatic liver tumors imparts 10-year overall survivals of >23% and 15%, respectively. This study indicates that long-term survival is possible with RFA treatment.

A Chlamydia trachomatis strain with a chemically generated amino acid substitution (P370L) in the cthtrA gene shows reduced elementary body production.

BACKGROUND: Chlamydia (C.) trachomatis is the most prevalent bacterial sexually transmitted infection worldwide and the leading cause of preventable blindness. Genetic approaches to investigate C. trachomatis have been only recently developed due to the organism's intracellular developmental cycle. HtrA is a critical stress response serine protease and chaperone for many bacteria and in C. trachomatis has been previously shown to be important for heat stress and the replicative phase of development using a chemical inhibitor of the CtHtrA activity. In this study, chemically-induced SNVs in the cthtrA gene that resulted in amino acid substitutions (A240V, G475E, and P370L) were identified and characterized. METHODS: SNVs were initially biochemically characterized in vitro using recombinant protein techniques to confirm a functional impact on proteolysis. The C. trachomatis strains containing the SNVs with marked reductions in proteolysis were investigated in cell culture to identify phenotypes that could be linked to CtHtrA function. RESULTS: The strain harboring the SNV with the most marked impact on proteolysis (cthtrA P370L) was detected to have a significant reduction in the production of infectious elementary bodies. CONCLUSIONS: This provides genetic evidence that CtHtrA is critical for the C. trachomatis developmental cycle.

Neutrophil-lymphocyte ratio is a simple and novel biomarker for prediction of survival after radioembolization for metastatic colorectal cancer.

PURPOSE: Previous studies have reported that an elevated preoperative Neutrophil-Lymphocyte Ratio (NLR) is associated with poor prognosis in patients with various solid tumors including colorectal cancer (CRC). Here, we examine whether NLR predicts survival in patients with unresectable CRC metastases undergoing hepatic radioembolization. METHODS: A retrospective review of 104 consecutive patients with unresectable metastatic CRC who were treated with radioembolization after failing first and second-line chemotherapy. RESULTS: Between 2002 and 2012, the median NLR for all patients was 4.6. Using receiver operating curve analysis, there was no difference between using an NLR cut-off of 4.6 or 5. Forty-eight patients had a high NLR of ≥5 and 56 patients had an NLR of <5. Patients in both groups had similar previous extensive chemotherapy and liver-directed interventions. The median survival of patients with high NLR was 5.6 months (range 4.9-7.9 months) compared with 10.6 months (range 8.3-17.0 months) for patients with low NLR; a significant difference was found in overall survival (log-rank test; p = 0.001). Other factors associated with risk of death were extrahepatic spread of disease, presence of pulmonary nodules, previous liver-targeted intervention, and radiographic response. On multivariate analysis, high NLR, progressive radiographic response, and presence of extrahepatic disease remained independently associated with increased risk of death. CONCLUSIONS: NLR is a simply attainable, inexpensive, and useful biomarker to predict outcome in patients with metastatic colorectal cancer receiving radioembolization.

The Prognostic Role of Neutrophil-to-Lymphocyte Ratio in Patients with Unresectable Hepatocellular Carcinoma Treated with Radioembolization.

PURPOSE: To assess the prognostic value of neutrophil-to-lymphocyte ratio (NLR) in patients with unresectable intermediate- or advanced-stage hepatocellular carcinoma (HCC) treated with yttrium-90 radioembolization (RE). MATERIALS AND METHODS: Retrospective chart review was performed for 176 patients with intermediate- or advanced-stage HCC treated with RE between August 2000 and November 2012. The appropriate NLR cutoff was determined by receiver operating characteristic curves. Demographic, clinical, radiographic, and pathologic parameters were compared between patients with a normal NLR (< 5) and those with an elevated NLR (≥ 5) before RE. Barcelona Clinic Liver Cancer (BCLC) stage-stratified univariate and multivariate analyses were conducted to determine variables associated with overall survival. RESULTS: Under univariate analyses, patients with a normal NLR were found to have longer survival than individuals with a high NLR in intermediate/advanced-disease and advanced-disease cohorts. A multivariate Cox proportional-hazards model in the advanced-disease group confirmed that elevated NLR, high α-fetoprotein level, and low albumin level were independent predictors of worse survival. CONCLUSIONS: This study provides stage-dependent evidence for the prognostic role of NLR in the radioembolized HCC cohort. Patients with BCLC stage C disease with elevated NLR may not derive benefit from RE, and other intervening modalities should be explored in this subpopulation.

Survival and tolerability of liver radioembolization: a comparison of elderly and younger patients with metastatic colorectal cancer.

AIM: To evaluate the outcomes among elderly (≥70 years) and younger patients (<70 years) with liver-dominant metastatic colorectal cancer (mCRC) who received radioembolization (RE) as salvage therapy. METHODS: A retrospective review of 107 consecutive patients with unresectable mCRC treated with RE after failing first- and second-line chemotherapy. RESULTS: From 2002 to 2012, 44 elderly and 63 younger (<70 years) patients received RE. Patients had similar previous extensive chemotherapy and liver-directed interventions. Using modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria, either a stable or a partial radiographical response was seen in 65.8% of the younger compared with 76.5% of the elderly patients. RE was equally well tolerated in both groups and common procedure-related adverse events were predominantly grade 1-2 and of short duration. No significant difference was found with regard to overall median survival between younger [8.4 months; 95% confidence interval (CI) = 6.2-10.6] or elderly patients (8.2 months; 95% CI = 5.9-10.5, P = 0.667). The presence of extrahepatic disease at the time of RE was associated with a significantly worse median survival in both groups. CONCLUSION: Radioembolization appears to be as well tolerated and effective for the elderly as it is for younger patients with mCRC. Age alone should not be a discriminating factor for the use of radioembolization in the management of mCRC patients.

Gene deletions and amplifications in human hepatocellular carcinomas: correlation with hepatocyte growth regulation.

Tissues from 98 human hepatocellular carcinomas (HCCs) obtained from hepatic resections were subjected to somatic copy number variation (CNV) analysis. Most of these HCCs were discovered in livers resected for orthotopic transplantation, although in a few cases, the tumors themselves were the reason for the hepatectomies. Genomic analysis revealed deletions and amplifications in several genes, and clustering analysis based on CNV revealed five clusters. The LSP1 gene had the most cases with CNV (46 deletions and 5 amplifications). High frequencies of CNV were also seen in PTPRD (21/98), GNB1L (18/98), KIAA1217 (18/98), RP1-1777G6.2 (17/98), ETS1 (11/98), RSU1 (10/98), TBC1D22A (10/98), BAHCC1 (9/98), MAML2 (9/98), RAB1B (9/98), and YIF1A (9/98). The existing literature regarding hepatocytes or other cell types has connected many of these genes to regulation of cytoskeletal architecture, signaling cascades related to growth regulation, and transcription factors directly interacting with nuclear signaling complexes. Correlations with existing literature indicate that genomic lesions associated with HCC at the level of resolution of CNV occur on many genes associated directly or indirectly with signaling pathways operating in liver regeneration and hepatocyte growth regulation.

Yttrium-90 radioembolization as a bridge to liver transplantation: a single-institution experience.

PURPOSE: To evaluate our experience with the use of yttrium-90 ((90)Y) radioembolization in maintaining potential candidacy and, in some instances, downstaging hepatocellular carcinoma (HCC) that does not meet Milan criteria for liver transplantation. MATERIALS AND METHODS: A retrospective review of 20 consecutive patients with HCC who were listed to receive a liver transplant and were treated with (90)Y radioembolization as a sole modality for locoregional "bridge" therapy was performed. Demographics, radiographic and pathologic response, survival, and recurrences were examined. RESULTS: Twenty-two (90)Y treatments were performed in 20 patients before transplantation. Median time from first treatment to transplantation was 3.5 months. HCC in 14 patients met the Milan criteria at the time of the first (90)Y treatment, and HCC in six did not. All cases that originally met the Milan criteria remained within the criteria before transplantation, and two of six patients whose disease did not meet the criteria (33%) had their disease successfully downstaged to meet the criteria. Overall, nine patients (45%) had complete or partial radiologic response to (90)Y radioembolization according to modified Response Evaluation Criteria In Solid Tumors. Complete necrosis of tumor with no evidence of viable tumor on pathologic examination was observed in five patients (36%) whose disease met the Milan criteria. CONCLUSIONS: Particularly in regions with long wait list times, (90)Y treatment is effective in maintaining tumor size in potential liver transplantation candidates with HCC. In addition, it can also be considered as a downstaging therapy in select patients before transplantation.

A validated model for predicting outcome after liver transplantation: implications on transplanting the extremely sick.

Given the organ shortage, there is a need to optimize outcome after liver transplantation (LT). We defined posttransplant hospital length of stay > 60 days (LOS > 60) as a surrogate of suboptimal outcome. In the first phase of the study, a 'Study cohort' (SC) of 643 patients was used to identify risk factors and construct a mathematical model to identify recipients with anticipated inferior results. In the second phase, a cohort of 417 patients was used for validation of the model ['Validation Cohort' (VC)]. In the SC, 65 patients (10.1%) had LOS > 60 days. One- and 3-year patient/graft survival rates were 81.9%/76.1% and 73.4%/67.4%, respectively. Patient and graft survival rates of those with LOS > 60 days were inferior (P < 0.0001), while transplant cost was greater [3.42 relative units (RU) vs. 1 RU, P < 0.0001]. In a multivariable analysis, pretransplant dialysis (P < 0.001), mechanical ventilation (P < 0.015), MELD (P < 0.003), and age (P < 0.009) were predictors of LOS > 60 days [ROC curve - 0.75 (95% CI 0.70, 0.81)]. In the VC, 53 patients (12.7%) were expected to have adverse outcome by the model. These patients had longer LOS (P < 0.0001), higher cost (<0.0001), and inferior patient and graft survival (P < 0.007).

Proteolytic activation of Chlamydia trachomatis HTRA is mediated by PDZ1 domain interactions with protease domain loops L3 and LC and beta strand ß5.

Chlamydia trachomatis is a bacterial pathogen responsible for one of the most prevalent sexually transmitted infections worldwide. Its unique development cycle has limited our understanding of its pathogenic mechanisms. However, CtHtrA has recently been identified as a potential C. trachomatis virulence factor. CtHtrA is a tightly regulated quality control protein with a monomeric structural unit comprised of a chymotrypsin-like protease domain and two PDZ domains. Activation of proteolytic activity relies on the C-terminus of the substrate allosterically binding to the PDZ1 domain, which triggers subsequent conformational change and oligomerization of the protein into 24-mers enabling proteolysis. This activation is mediated by a cascade of precise structural arrangements, but the specific CtHtrA residues and structural elements required to facilitate activation are unknown. Using in vitro analysis guided by homology modeling, we show that the mutation of residues Arg362 and Arg224, predicted to disrupt the interaction between the CtHtrA PDZ1 domain and loop L3, and between loop L3 and loop LD, respectively, are critical for the activation of proteolytic activity. We also demonstrate that mutation to residues Arg299 and Lys160, predicted to disrupt PDZ1 domain interactions with protease loop LC and strand ß5, are also able to influence proteolysis, implying their involvement in the CtHtrA mechanism of activation. This is the first investigation of protease loop LC and strand ß5 with respect to their potential interactions with the PDZ1 domain. Given their high level of conservation in bacterial HtrA, these structural elements may be equally significant in the activation mechanism of DegP and other HtrA family members.

Radiofrequency ablation compared to resection in early-stage hepatocellular carcinoma.

OBJECTIVES: This study aimed to compare survival outcomes after hepatic resection (HR) and radiofrequency ablation (RFA) in early-stage hepatocellular carcinoma (HCC) at a Western hepatobiliary centre. METHODS: Demographic details, clinicopathologic tumour characteristics and survival outcomes were compared among non-transplant candidate patients undergoing HR (n= 50) and RFA (n= 60) for early-stage HCC during 2001-2011. RESULTS: Patients who underwent HR had larger tumours, a longer length of stay and a higher rate of postoperative complications. After a median follow-up of 29 months, there were no significant differences between the treatment groups in 1-, 3- and 5-year overall survival (OS) [RFA group: 86%, 50%, 35%, respectively; HR group: 88%, 68%, 47%, respectively (P= 0.222)] or disease-free survival (DFS) [RFA group: 68%, 42%, 28%, respectively; HR group: 66%, 42%, 34%, respectively (P= 0.823)]. The 58 patients who underwent RFA demonstrated ablation success on follow-up computed tomography at 3 months. Of these, 96.5% of patients showed sustained ablation success over the entire follow-up period. In a subgroup analysis of patients with tumours measuring 2-5 cm, no differences in OS or DFS emerged between the HR and RFA groups. Similarly, no significant differences in outcomes in patients with Child-Pugh class A cirrhosis were seen between the RFA and HR groups. CONCLUSIONS: Radiofrequency ablation is comparable with HR in terms of OS and DFS. It is a reasonable alternative as a first-line treatment for HCC in well-selected patients who are not candidates for transplant.

EFFECTIVE DOSE COEFFICIENTS FOR RADON AND PROGENY: A REVIEW OF ICRP AND UNSCEAR VALUES.

The International Commission on Radiological Protection (ICRP) publishes guidance on protection against radon exposure in homes and workplaces. ICRP Publication 137 recommends a dose coefficient of 3 mSv per mJ h m-3 (~10 mSv WLM-1) to be used in most circumstances of radon exposure, for workers in buildings and in underground mines. Recently, United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) reviewed radon epidemiology and dosimetry and concluded that its established dose coefficient of 1.6 mSv per mJ h m-3 (5.7 mSv WLM-1) should be retained for use in its comparisons of radiation exposures from different sources in a population. This paper explains and compares the reviews of the scientific evidence from UNSCEAR and ICRP. It is shown that the UNSCEAR and ICRP reviews are consistent and support the use of the ICRP reference dose coefficients for radiation protection purposes. It is concluded that the ICRP dose coefficient should be used to calculate doses to workers.

Comparison of surgical methods in liver transplantation: retrohepatic caval resection with venovenous bypass (VVB) versus piggyback (PB) with VVB versus PB without VVB.

Use of piggyback technique (PB) and elimination of venovenous bypass (VVB) have been advocated in adult liver transplantation (LT). However, individual contribution of these two modifications on clinical outcomes has not been fully investigated. We performed a retrospective review of 426 LTs within a 3-year period, when three different surgical techniques were employed per the surgeons' preference: retrohepatic caval resection with VVB (RCR+VVB) in 104 patients, PB with VVB (PB+VVB) in 148, and PB without VVB (PB-Only) in 174. The primary outcomes were intraoperative blood transfusion and the patient and graft survivals. Demographic profiles were similar, except younger recipient age in RCR+VVB and fewer number of grafts with cold ischemic time over 16 h in PB-Only. PB-Only required lesser intraoperative red blood cells (P=0.006), fresh frozen plasma (P=0.005), and cell saver return (P=0.007); had less incidence of acute renal failure (P=0.001), better patient survival (P=0.039), and graft survival (P=0.003). The benefits of PB+VVB were only found in shortened total surgical time (P=0.0001) and warm ischemic time (P=0.0001), and less incidence of acute renal failure (P=0.001) than RCR+VVB. PB-Only method seemed to provide the best clinical outcome. The benefit of PB was not fully achieved when it was used with VVB.