Efficient algorithm to compute mutually connected components in interdependent networks

Mutually connected components (MCCs) play an important role as a measure of resilience in the study of interdependent networks. Despite their importance, an efficient algorithm to obtain the statistics of all MCCs during the removal of links has thus far been absent. Here, using a well-known fully dynamic graph algorithm, we propose an efficient algorithm to accomplish this task. We show that the time complexity of this algorithm is approximately O(N(1.2)) for random graphs, which is more efficient than O(N(2)) of the brute-force algorithm. We confirm the correctness of our algorithm by comparing the behavior of the order parameter as links are removed with existing results for three types of double-layer multiplex networks. We anticipate that this algorithm will be used for simulations of large-size systems that have been previously inaccessible.

Resection of metachronous adrenal metastasis after liver resection and transplantation for hepatocellular carcinoma

BACKGROUND

This study analyzed the patient survival outcomes following the resection of hepatocellular carcinoma (HCC) metachronous adrenal metastasis (MAM) in patients who had undergone liver resection or liver transplantation (LT).

METHODS

Clinical results were analyzed retrospectively in 26 patients with MAM-HCC who underwent adrenalectomy.

RESULTS

The mean interval between initial surgery and adrenalectomy was significantly shorter in the resection group than in the LT group (18.3 ± 14.4 vs. 42.6 ± 13.8 months, p < 0.001). Of 19 resected patients, four had adrenal metastases on the right side, 12 on the left side and three bilaterally, with a mean tumor diameter of 3.6 ± 1.5 cm. Ten of these patients underwent open surgery and nine underwent laparoscopic surgery; all patients experienced recurrences within 18 months and 20.3% survived 5 years after adrenalectomy. Of 7 patients who underwent LT, four had adrenal metastases on the right side and three on the left side, with a mean tumor diameter of 3.4 ± 1.8 cm. Six of these patients underwent open surgery and one underwent laparoscopic surgery. Five-year recurrence and patient survival rates after adrenalectomy were 28.6 and 85.7%, respectively.

CONCLUSIONS

Adrenalectomy is indicated in patients with isolated MAM-HCC. Comparisons with other locoregional treatment modalities and multicenter studies with additional patients are needed to validate the role of adrenalectomy.

Associations between serum 25-hydroxyvitamin D and bone mineral density and proximal femur geometry in Koreans: the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2009

The association between 25-hydroxyvitamin D (25(OH)D) levels and bone mineral density (BMD) and proximal femur bone geometry was examined in the Korean population. A positive relationship between skeletal health and 25(OH)D levels was observed. However, there were no significant differences in skeletal health between the groups with 25(OH)D level of 50-75 nmol/L and greater than 75 nmol/L.

INTRODUCTION

Vitamin D plays an important role in calcium and phosphate homeostasis and normal mineralization of bone. However, the optimal level of vitamin D for skeletal health has not been clearly established. We analyzed the associations between serum 25(OH)D and BMD and proximal femur bone geometry and determined the optimal 25(OH)D level.

METHODS

This was a cross-sectional study of 10,062 participants (20-95 years, 4,455 men, 5,607 women) in the Fourth Korea National Health and Nutrition Examination Surveys (KNHANES IV) conducted from 2008 to 2009. Participants were divided into groups according to 25(OH)D level (<25, 25-50, 50-75, and ≥75 nmol/L). BMD and proximal femur geometric indices were measured.

RESULTS

The group with 25(OH)D levels of 50-75 nmol/L had greater bone density values, with the exception of the lumbar spine, and also had greater femur neck cortical thickness, cross-sectional area, and cross-sectional moment of inertia, as well as a lesser buckling ratio than the groups with 25(OH)D level of 25-50 nmol/L and less than 25 nmol/L. However, there were no significant differences in BMD and proximal femur geometry properties between the groups with 50-75 nmol/L and greater than 75 nmol/L of 25(OH)D.

CONCLUSION

The skeletal outcomes, including BMD and proximal femur geometric indices observed in this study, suggest that serum 25(OH)D levels of 50 to <75 nmol/L are optimal for skeletal health.

Prevalence analysis of de novo hepatic steatosis following pylorus-preserving pancreaticoduodenectomy

BACKGROUND

Prevalence of hepatic steatosis following pylorus-preserving pancreaticoduodenectomy (PPPD) is high. This study intended to reveal the prevalence and patterns of de novo hepatic steatosis following PPPD.

METHODS

We investigated postoperative de novo hepatic steatosis following PPPD (n = 101) with a control group of bile duct resection (BDR) (n = 54).

RESULTS

At postoperative 1 year, hepatic steatosis occurred in 21 of 82 patients (25.6%) of PPPD group and in 2 of 47 patients (4.3%) of BDR group (p = 0.001). Thereafter, at 2 to 5 years, a high prevalence of hepatic steatosis persisted in the PPPD group, but no further occurrence developed in BDR group. Once steatosis developed, it persisted until the end of the study period or patient death. Five-year cumulative incidence of hepatic steatosis was 26.7% in the PPPD group and 3.7% in BDR group (p < 0.001). Univariate analyses showed that patient sex, age, body mass index, blood lipid profile, recurrence of tumor, and diabetes did not have significant influence on the development of hepatic steatosis following PPPD.

CONCLUSIONS

De novo hepatic steatosis may develop in a not negligible proportion of patients undergone PPPD. Multicenter studies with a high number of patients are needed to elucidate its pathogenesis and to find effective treatment for pancreaticoduodenectomy-associated hepatic steatosis.

Blind and myopic ants in heterogeneous networks

The diffusion processes on complex networks may be described by different Laplacian matrices due to heterogeneous connectivity. Here we investigate the random walks of blind ants and myopic ants on heterogeneous networks: While a myopic ant hops to a neighbor node every step, a blind ant may stay or hop with probabilities that depend on node connectivity. By analyzing the trajectories of blind ants, we show that the asymptotic behaviors of both random walks are related by rescaling time and probability with node connectivity. Using this result, we show how the small eigenvalues of the Laplacian matrices generating the two random walks are related. As an application, we show how the return-to-origin probability of a myopic ant can be used to compute the scaling behaviors of the Edwards-Wilkinson model, a representative model of load balancing on networks.

Genomic portrait of resectable hepatocellular carcinomas: implications of RB1 and FGF19 aberrations for patient stratification

Hepatic resection is the most curative treatment option for early-stage hepatocellular carcinoma, but is associated with a high recurrence rate, which exceeds 50% at 5 years after surgery. Understanding the genetic basis of hepatocellular carcinoma at surgically curable stages may enable the identification of new molecular biomarkers that accurately identify patients in need of additional early therapeutic interventions. Whole exome sequencing and copy number analysis was performed on 231 hepatocellular carcinomas (72% with hepatitis B viral infection) that were classified as early-stage hepatocellular carcinomas, candidates for surgical resection. Recurrent mutations were validated by Sanger sequencing. Unsupervised genomic analyses identified an association between specific genetic aberrations and postoperative clinical outcomes. Recurrent somatic mutations were identified in nine genes, including TP53, CTNNB1, AXIN1, RPS6KA3, and RB1. Recurrent homozygous deletions in FAM123A, RB1, and CDKN2A, and high-copy amplifications in MYC, RSPO2, CCND1, and FGF19 were detected. Pathway analyses of these genes revealed aberrations in the p53, Wnt, PIK3/Ras, cell cycle, and chromatin remodeling pathways. RB1 mutations were significantly associated with cancer-specific and recurrence-free survival after resection (multivariate P = 0.038 and P = 0.012, respectively). FGF19 amplifications, known to activate Wnt signaling, were mutually exclusive with CTNNB1 and AXIN1 mutations, and significantly associated with cirrhosis (P = 0.017).

CONCLUSION

RB1 mutations can be used as a prognostic molecular biomarker for resectable hepatocellular carcinoma. Further study is required to investigate the potential role of FGF19 amplification in driving hepatocarcinogenesis in patients with liver cirrhosis and to investigate the potential of anti-FGF19 treatment in these patients.

Preoperative coronary calcium score is predictive of early postoperative cardiovascular complications in liver transplant recipients

BACKGROUND

Coronary computed tomographic angiography (coronary CT) is a non-invasive test for diagnosis of cardiac function. Coronary calcium scores determined by coronary CT are associated with cardiovascular risk factors. However, no studies have investigated the association between coronary calcium scores and cardiovascular complications after liver transplantation (LT). We therefore evaluated the utility of preoperative coronary calcium scores for predicting early postoperative cardiovascular complications in LT recipients.

METHODS

Between 2010 and 2012, 443 LT recipients were analysed retrospectively. Preoperative cardiovascular assessments, including coronary CT, were performed. A coronary calcium score >400 was defined as a positive finding. Predictive factors of early postoperative cardiovascular complications were evaluated by univariate and multivariate analyses. Major cardiovascular complications occurring during a period of 1 month after LT were noted.

RESULTS

Of the 443 patients, 38 (8.6%) experienced one or more cardiovascular complications. Positive coronary CT findings were seen in 11 (2.5%) patients. In the multivariate analysis, a coronary calcium score >400 {odds ratio (OR)=4.62 [95% confidence interval (CI): 1.14-18.72], P=0.032} and female sex [OR=2.76 (1.37-5.57), P=0.005] were predictive of cardiovascular complications.

CONCLUSIONS

A preoperative coronary calcium score of >400 predicted cardiovascular complications occurring 1 month after LT, suggesting that preoperative evaluation of coronary calcium scores could help predict early postoperative cardiovascular complications in LT recipients.

Ground-state energy of the q-state Potts model: The minimum modularity

A wide range of interacting systems can be described by complex networks. A common feature of such networks is that they consist of several communities or modules, the degree of which may quantified as the modularity. However, even a random uncorrelated network, which has no obvious modular structure, has a finite modularity due to the quenched disorder. For this reason, the modularity of a given network is meaningful only when it is compared with that of a randomized network with the same degree distribution. In this context, it is important to calculate the modularity of a random uncorrelated network with an arbitrary degree distribution. The modularity of a random network has been calculated [Reichardt and Bornholdt, Phys. Rev. E 76, 015102 (2007)PLEEE81539-375510.1103/PhysRevE.76.015102]; however, this was limited to the case whereby the network was assumed to have only two communities, and it is evident that the modularity should be calculated in general with q(≥2) communities. Here we calculate the modularity for q communities by evaluating the ground-state energy of the q-state Potts Hamiltonian, based on replica symmetric solutions assuming that the mean degree is large. We found that the modularity is proportional to 〈sqrt[k]〉/〈k〉 regardless of q and that only the coefficient depends on q. In particular, when the degree distribution follows a power law, the modularity is proportional to 〈k〉^{-1/2}. Our analytical results are confirmed by comparison with numerical simulations. Therefore, our results can be used as reference values for real-world networks.

Postoperative radiotherapy for gallbladder cancer

AIM

To evaluate the results of postoperative radiotherapy (PORT) and to identify prognostic factors for gallbladder cancer (GBC).

PATIENTS AND METHODS

We retrospectively analyzed 86 patients with GBC who underwent potentially curative surgical resection and PORT between November 1993 and December 2009. All patients received three-dimensional conformal radiotherapy and 61 patients (71%) had concurrent chemotherapy. Survival outcomes including locoregional control (LRC), disease-free survival (DFS) and overall survival (OS) rates were analyzed.

RESULTS

The median follow-up period was 83 months for surviving patients. The 5-year OS, DFS and LRC rates were 42%, 36% and 73%, respectively. Isolated locoregional recurrence as first failure occurred in seven patients (8%). On multivariate analysis, the postoperative carbohydrate antigen 19-9 (CA 19-9) level was a significant prognostic factor for LRC, DFS and OS.

CONCLUSION

Adjuvant radiotherapy might be an effective treatment in terms of LRC in GBC. Postoperative CA 19-9 might be useful as a surrogate marker for survival.

Fast algorithm for relaxation processes in big-data systems

Relaxation processes driven by a Laplacian matrix can be found in many real-world big-data systems, for example, in search engines on the World Wide Web and the dynamic load-balancing protocols in mesh networks. To numerically implement such processes, a fast-running algorithm for the calculation of the pseudoinverse of the Laplacian matrix is essential. Here we propose an algorithm which computes quickly and efficiently the pseudoinverse of Markov chain generator matrices satisfying the detailed-balance condition, a general class of matrices including the Laplacian. The algorithm utilizes the renormalization of the Gaussian integral. In addition to its applicability to a wide range of problems, the algorithm outperforms other algorithms in its ability to compute within a manageable computing time arbitrary elements of the pseudoinverse of a matrix of size millions by millions. Therefore our algorithm can be used very widely in analyzing the relaxation processes occurring on large-scale networked systems.

Sodium nitroprusside suppresses male fertility in vitro

Sodium nitroprusside is a nitric oxide donor involved in the regulation of the motility, hyperactivation, capacitation, and acrosome reaction (AR) of spermatozoa. However, the molecular mechanism underlying this regulation has not yet been elucidated. Therefore, this study was designed to evaluate the molecular basis for the effects of sodium nitroprusside on different processes in spermatozoa and its consequences on subsequent oocyte fertilization and embryo development. In this in vitro study, mouse spermatozoa were incubated with various concentrations of sodium nitroprusside (1, 10, and 100 μM) for 90 min. Our results showed that sodium nitroprusside inhibited sperm motility and motion kinematics in a dose-dependent manner by significantly enhancing intracellular iron and reactive oxygen species (ROS), and decreasing Ca(2+), and adenosine triphosphate levels in spermatozoa. Moreover, short-term exposure of spermatozoa to sodium nitroprusside increased the tyrosine phosphorylation of sperm proteins involved in PKA-dependent regulation of intracellular calcium levels, which induced a robust AR. Finally, sodium nitroprusside significantly decreased the rates of fertilization and blastocyst formation during embryo development. Based on these results, we propose that sodium nitroprusside increases ROS production and precocious AR may alter overall sperm physiology, leading to poor fertilization and compromised embryonic development.

Biliary stricture is the only concern in ABO-incompatible adult living donor liver transplantation in the rituximab era

BACKGROUND & AIMS

With the introduction of rituximab prophylaxis, the survival of ABO-incompatible (ABOi) adult living donor liver transplant (ALDLT) has been strikingly improved due to the decreased incidence of antibody-mediated rejection. However, biliary stricture (BS) related to ABO incompatibility remains an unresolved concern.

METHODS

Excluding 105 dual graft ALDLTs, 1102 ALDLT cases including 142 ABOi recipients were included in this study. The desensitization protocol for overcoming the ABO blood group barrier comprised pretransplant plasma exchange, and rituximab (300-375 mg/m(2) BSA).

RESULTS

The mean follow-up period was 34.2 ± 15.4 months. The cumulative graft and patient survival rates were comparable in the two groups. The 1- and 3-year BS-free survival rates of ABOi ALDLT were 81.5 and 79.0%, respectively, lower than those of ABOc ALDLT (87.6 and 85.7%, respectively, p=0.022). In the risk factor analysis, diameter of graft bile duct opening <5mm, antecedent acute cellular rejection, and ABO incompatibility were independent risk factors for BS. Diffuse intrahepatic biliary stricture (DIHBS) exclusively occurred in 12 patients (8.5%) receiving ABOi ALDLT. The deaths of 3 patients and 4 cases of re-transplantation were related to DIHBS. Graft and patient survival rates were significantly reduced in ABOi ALDLT recipients with DIHBS. However, we failed to identify any significant risk factors for DIHBS.

CONCLUSIONS

The incidence of BS in ABOi ALDLT is higher than in ABOc, mainly due to the fact of DIHBS which significantly affected survival outcomes. To predict and prevent DIHBS, we need further studies to identify significant risk factors.

Pancreatic atrophy relative to external versus internal drainage of the pancreatic duct after pylorus-preserving pancreaticoduodenectomy

BACKGROUND

Atrophy of the pancreatic parenchyma, which occurs frequently after pylorus-preserving pancreaticoduodenectomy (PPPD), is often associated with pancreatic exocrine insufficiency. Many surgeons prefer to insert a drainage tube into the remnant pancreatic duct primarily to prevent pancreatic leakage at the pancreaticojejunostomy (PJ) after PPPD. Drainage methods vary widely but can be roughly classified as internal or external drainage. This study intended to evaluate their effects on pancreatic parenchymal atrophy following PPPD.

METHODS

Fifty-seven patients who underwent PPPD were retrospectively divided into two groups, 28 who underwent external and 29 who underwent internal pancreatic drainage. External drainage tubes were removed 4 weeks after PPPD. The volume of the pancreatic parenchyma was serially measured on abdominal computed tomography (CT) scans before PPPD, as well as 7 days and 3, 6, and 12 months after surgery. Degree of pancreatic parenchymal atrophy was determined by calculating pancreatic volume relative to that on day 7.

RESULTS

Univariate analysis showed that patient sex, age, body mass index, concurrent pancreatitis, pathology, and types of PJ did not significantly affect changes in pancreatic volume following PPPD. The degree of pancreatic volume atrophy did not differ significantly in the external and internal drainage groups. No patient in the external drainage group experienced drainage-related surgical complications. The incidence of PJ leak was comparable in the two groups. Postoperative pancreatic atrophy did not induce new-onset diabetes mellitus at 1 year.

CONCLUSIONS

Both external and internal pancreatic drainage methods showed similar atrophy rate of the pancreatic parenchyma following PPPD.

Changes in left portal vein diameter in live liver donors after right hemihepatectomy for living donor liver transplantation

BACKGROUND/AIMS

To evaluate changes in left portal vein(LPV) diameter and its effect on changes of remnant liver volume(RLV) and splenic volume(SV) in live liver donors after right hemihepatectomy.

METHODOLOGY

From November 2008 to May 2009, 92 live liver donors were included. On preoperative, postoperative 1-week and 1-month CT, we measured LPV diameters(LPVB, LPV1W, LPV1M), RLVs(RLVB, RLV1W, RLV1M) and SVs(SVB, SV1W, SV1M). Percentage-intervalchanges were analyzed. The relationships between %LPV1W-B and other parameters were evaluated by univariate regression analyses.

RESULTS

On postoperative 1-week, LPV1W invariably decreased. However, RLV1W and SV1W increased. %RLVB and %RLV1W-B were significantly associated with %LPV1W-B(P=.016,.011). On postoperative 1-month, mean %LPV1M-1W, %LPV1M-B, %SV1M-1W and %SV1M-B were 108.1±9.8%, 82.9±11.8%, 99.3±11.4% and 146.9±23.0%. Although %RLV1M-B or %RLV1M-1W were not related with %LPV1W-B(P=.034,.401), there were negative correlations between %LPV1W-B and %SV1M-1W or %SV1M-B(P=.004,.007).

CONCLUSIONS

LPV diameter mostly decreases following right hemihepatectomy and improves spontaneously. Besides extent of hepatectomy, %LPV1W-B may be another indicator predicting splenic enlargement.

Spatially varying regularization of deconvolution in 3D microscopy

Confocal microscopy has become an essential tool to explore biospecimens in 3D. Confocal microcopy images are still degraded by out-of-focus blur and Poisson noise. Many deconvolution methods including the Richardson-Lucy (RL) method, Tikhonov method and split-gradient (SG) method have been well received. The RL deconvolution method results in enhanced image quality, especially for Poisson noise. Tikhonov deconvolution method improves the RL method by imposing a prior model of spatial regularization, which encourages adjacent voxels to appear similar. The SG method also contains spatial regularization and is capable of incorporating many edge-preserving priors resulting in improved image quality. The strength of spatial regularization is fixed regardless of spatial location for the Tikhonov and SG method. The Tikhonov and the SG deconvolution methods are improved upon in this study by allowing the strength of spatial regularization to differ for different spatial locations in a given image. The novel method shows improved image quality. The method was tested on phantom data for which ground truth and the point spread function are known. A Kullback-Leibler (KL) divergence value of 0.097 is obtained with applying spatially variable regularization to the SG method, whereas KL value of 0.409 is obtained with the Tikhonov method. In tests on a real data, for which the ground truth is unknown, the reconstructed data show improved noise characteristics while maintaining the important image features such as edges.

Tailored long-term immunosuppressive regimen for adult liver transplant recipients with hepatocellular carcinoma

Backgrounds/Aims

There are few guidelines for tailored immunosuppressive regimens for liver transplantation (LT) recipients with hepatocellular carcinoma (HCC). To establish long-term immunosuppressive regimens suitable for Korean adult LT recipients, we analyzed those that were currently in use at a single high-volume institution.

Methods

This cross-sectional study comprises three parts including review of the immunosuppressive regimens used to manage 2,147 adult LT outpatients, review of LT recipients who were diagnosed of HCC at LT, and review of LT recipients who suffered from HCC recurrence.

Results

In 1,000 adult LT recipients who were living more than 5 years with no adverse events, 916 received a calcineurin inhibitor (CNI)-based therapy (CNI only in 520; CNI with mycophenolate mofetil [MMF] in 396) and 84 were receiving an MMF-based therapy (MMF only in 45; MMF with minimal CNI in 39). Tacrolimus was preferred over cyclosporine for both monotherapy and combination therapy along the passage of posttransplant period. There was no difference in selection of immunosuppressants, target blood concentration, and rate of combination therapy between LT recipients with and without HCC, except for the first 1 year. Sirolimus-based regimens were applied in 21 patients who showed HCC recurrence. Sorafenib was often used after conversion to sirolimus.

Conclusions

Tailored immunosuppressive regimen covering the long-term posttransplant period should be established after consideration of individualized patient profiles including HCC.

Post-transplant assessment of consciousness in acute-on-chronic liver failure patients undergoing liver transplantation using bispectral index monitoring

PURPOSE

Deterioration of consciousness is a critical situation for liver transplantation (OLT) recipients. The bispectral (BIS) index based on electroencephalographic parameters, is primarily used to monitor the depth of unconsciousness. The present study sought to assess the usefulness of posttransplant BIS index to monitor acute-on-chronic liver failure patients.

METHODS

This 1-year retrospective study of 28 adult patients with acute-on-chronic liver failure was performed from July 2011 to June 2012, using post-transplant BIS monitoring.

RESULTS

The mean patient age was 51 ± 8 years. Their mean pretransplant Child-Turcotte-Pugh score was 12.3 ± 1.4, and the mean Model for End-stage Liver Disease score, 36.4 ± 5.9. After OLT, the mean initial Glasgow Coma Scale (GCS) score and BIS index were 3.4 ± 1.7 and 43.5 ± 9.1, respectively. After 6 hours the mean GCS and BIS values rose to 8.6 ± 4.0 and 52.4 ± 10.3 and after 12 hours to 9.7 ± 3.4 and 61.3 ± 15.7 respectively. Eye opening in response to a voice occurred at a mean of 8.9 ± 6.7 hours after arrival in the intensive care unit regardless of graft function. The mean GCS and BIS values were 10.6 ± 2.8 and 69.1 ± 13.5, respectively. The endotracheal tube was removed after a median of 140 hours; 9 patients required a tracheostomy. Among them 2 died within the first 3 months after OLT.

CONCLUSIONS

BIS monitoring is a noninvasive, simple, easy-to-interpret method to measure consciousness among patients intubated with an endotracheal tube.

A pilot study on the safety and efficacy of generic mycophenolate agent as conversion maintenance therapy in stable liver transplant recipients

PURPOSE

The patent covering mycophenolate mofetil (MMF) in Korea has expired and, thus, several generic MMF agents are now commercially available. The supply of Cellcept (Roche Korea) was interrupted at the end of 2011, so it was inevitable that a generic MMF would be used instead. During this period, we performed a prospective pilot study to examine the safety and efficacy of a generic mycophenolate agent (Myconol: Hanmi Pharmaceutical, Seoul Korea) for use as conversion maintenance therapy in stable liver transplantation (OLT) recipients.

METHODS

OLT recipients, who were treated with MMF on an outpatient basis from January 2012 to March 2012, attended follow-up interviews conducted. The patients had undergone OLT ≥ 2 years before the study, had tolerated Cellcept, and showed stable liver function. Fifty-three patients were followed up for more than 3 months after conversion to the same dose of Myconol.

RESULTS

After conversion to Myconol, 6 patients (11.3%) experienced new side effects, which disappeared when they reverted to Cellcept (n = 5) or stopped taking Myconol medication (n = 1). The side effects associated with Myconol included gastrointestinal symptoms (indigestion and diarrhea; n = 3), skin eruptions (n = 1), pruritus (n = 1), and insomnia (n = 1). The mean mycophenolic acid levels were 1.71 ± 0.88 μg/mL for Cellcept and 1.83 ± 0.91 μg/mL for Myconol, which showed a strong correlation (r(2) = 0.92, P < .001).

CONCLUSIONS

Myconol showed similar pharmacokinetics to those of Celcept, but a small proportion of patients experienced agent-specific side effects; therefore, patients should be closely monitored when taking Myconol. Also, further studies, with a greater number of patients, are required to identify the full spectrum of drug-associated side effects.

Clinical outcomes of Pneumocystis carinii pneumonia in adult liver transplant recipients

PURPOSE

Pneumocystis carinii pneumonia (PCP) is an opportunistic infection associated with morbidity and mortality in solid-organ transplant recipients. We retrospectively assessed the characteristics and outcomes of liver transplant (OLT) recipients with PCP compared with those of patients with severe non-P carinii pneumonia (non-PCP) who required intensive care with mechanical ventilation.

METHODS

During the 2-year period between January 2008 and December 2009, 43 adult OLT recipients had severe pneumonia requiring mechanical ventilation; of these, 8 (19%) had PCP. During this period, routine antibiotic prophylaxis was administered for the first 6 months after OLT.

RESULTS

The median period from OLT to development of PCP was 9.5 months (range, 1-67); the 1-year incidence was 0.9%. The 6 and 6 to 12-month incidences of non-PCP were 4.2% and 0.3%, respectively, and those of PCP were 0.3% and 0.6%, respectively. Four of 8 patients (50%) in the PCP group had a recent history of a rejection episode. PCP was associated with a higher incidence of prior antirejection treatment. There were no significant differences between PCP and non-PCP groups in age, gender, preoperative Model for End-stage Liver Disease score, primary diagnosis, graft type, and total number of rejection episodes.

CONCLUSIONS

These results indicate that the risk of PCP in OLT recipients is closely related to strong immunosuppressive treatment for acute cellular rejection episodes, suggesting the importance of PCP prophylaxis in these patients. Because most patients developed PCP at around 1 year, it may be advisable to prolong routine post-OLT PCP prophylaxis for 12 months, especially among patients receiving antirejection treatment.

Analysis of S gene mutation of the hepatitis B virus in adult liver transplant recipients showing resistance to hepatitis B immunoglobulin therapy

BACKGROUND

A considerable proportion of recipients of liver transplantations who are presented hepatitis B immunoglobulin (HBIG) monotherapy for hepatitis B virus (HBV) prophylaxis develop HBIG resistance. In this study, we investigated the mutation patterns in the major hydrophilic region (MHR) of amino acid sequences 100 to 160.

METHODS

Using the gene sequence analyzer for amino acid sequences 0 to 226 in the S/pre-S region we analyzed blood samples of 15 patients showing HBIG resistance after high-dose HBIG prophylaxis.

RESULTS

Various mutations in the MHR were observed in 14/15 samples: Gly145Arg mutation in 8/13 Adr subtype and 1/2 Ayw subtype samples (60%). The next most common mutation was Gly165Trp in 8/13 Adr subtype but neither of 2 Ayw subtype samples (53.3%). Concurrent antiviral resistance was noted in 5 patients: lamivudine (n = 5), or entecavir (n = 3), but not adefovir, suggesting the occurrence of simultaneous, antiviral cross-resistances. Two patients underwent retransplantation due to the progression of HBV infection despite vigorous antiviral therapy. At diagnosis of HBV recurrence, the mean HBV DNA load was 6.5 × 10(6) copies/mL; 4 patients showed paradoxical coexistence of anti-HBs and HBsAg. Currently, 2 subjects show low-level HBV DNA replication in peripheral blood, although the other 12 had no DNA replication after prolonged antiviral therapy.

CONCLUSIONS

This study suggested that various mutations in the "a" determinant were associated with HBIG resistance. Since treatment failure to rescue antiviral therapy was often associated with delayed detection of HBV recurrence rather than concurrent antiviral resistance, frequent HBV surveillance using more sensitive screening tests, such as HBeAg and HBV DNA polymerase chain reaction assay, seems to be mandatory.

Long-term survival outcomes for living donor liver transplant recipients with pathologically nonviable hepatocellular carcinoma

PURPOSE

Complete necrosis of hepatocellular carcinoma (HCC) lesions has occasionally been found by explant pathology after pretransplant neoadjuvant treatment. This study sought to investigate the long-term prognostic effect of loss of tumor viability after HCC treatment in living donor liver transplant (LDLT) recipients.

METHODS

We reviewed retrospectively the 5-year records of 37 patients who demonstrated nonviable HCC on explant pathology.

RESULTS

The most common primary disease was hepatitis-B-virus-associated liver cirrhosis (n = 34). Single explant tumors were found in 29 patients; the mean maximal tumor size was 2.1 ± 0.9 cm (range: 0.8-4.0). No patients showed microvascular invasion. The median level of alpha-fetoprotein was 12 ng/mL (range: 1-1160). The 1 patient who showed a recurrence at 20 months remains alive more than 6 years after adrenalectomy and repeated pulmonary metastasectomy. The 5-year HCC recurrence rate was thus 2.1%. There were 2 late mortalities, each due to graft failure and recurrent gastric cancer. The overall patient survival rate was 97.3% at 5 and 92.7% at 10 years.

CONCLUSIONS

The results of this study revealed that the loss of tumor viability induced by pretransplant neoadjuvant treatment definitely decreased the risk of post-transplant HCC recurrence. Therefore, patients with nonviable HCC can be regarded as members of a superselect group with minimal risk for HCC recurrence, and may be exempted from routine HCC screening.