Aligned Contrastive Predictive Coding

We investigate the possibility of forcing a self-supervised model trained using a contrastive predictive loss to extract slowly varying latent representations. Rather than producing individual predictions for each of the future representations, the model emits a sequence of predictions shorter than that of the upcoming representations to which they will be aligned. In this way, the prediction network solves a simpler task of predicting the next symbols, but not their exact timing, while the encoding network is trained to produce piece-wise constant latent codes. We evaluate the model on a speech coding task and demonstrate that the proposed Aligned Contrastive Predictive Coding (ACPC) leads to higher linear phone prediction accuracy and lower ABX error rates, while being slightly faster to train due to the reduced number of prediction heads.Comment: Published in Interspeech 202

Information Retrieval for ZeroSpeech 2021: The Submission by University of Wroclaw

We present a number of low-resource approaches to the tasks of the Zero Resource Speech Challenge 2021. We build on the unsupervised representations of speech proposed by the organizers as a baseline, derived from CPC and clustered with the k-means algorithm. We demonstrate that simple methods of refining those representations can narrow the gap, or even improve upon the solutions which use a high computational budget. The results lead to the conclusion that the CPC-derived representations are still too noisy for training language models, but stable enough for simpler forms of pattern matching and retrieval.Comment: Published in Interspeech 202

Relevance of Preoperative Hyperbilirubinemia in Patients Undergoing Hepatobiliary Resection for Hilar Cholangiocarcinoma

Preoperative hyperbilirubinemia is known to increase the risk of mortality and morbidity in patients undergoing resection for hilar cholangiocarcinoma. The aim of this study was to characterize the associations between the preoperative bilirubin concentration and the risk of postoperative mortality and severe complications to guide decision-making regarding preoperative biliary drainage. Eighty-one patients undergoing liver and bile duct resection for hilar cholangiocarcinoma between 2005 and 2015 were analyzed retrospectively. Postoperative mortality and severe complications, defined as a Clavien–Dindo grade of ≥III, were the primary and secondary outcome measures, respectively. The severe postoperative complications and mortality rates were 28.4% (23/81) and 11.1% (9/81), respectively. Patients with preoperative biliary drainage had significantly lower bilirubin concentrations (p = 0.028) than did those without. The preoperative bilirubin concentration was a risk factor of postoperative mortality (p = 0.003), with an optimal cut-off of 6.20 mg/dL (c-statistic = 0.829). The preoperative bilirubin concentration was a risk factor of severe morbidity (p = 0.018), with an optimal cut-off of 2.48 mg/dL (c-statistic = 0.662). These results indicate that preoperative hyperbilirubinemia is a major risk factor of negative early postoperative outcomes of patients who undergo surgical treatment for hilar cholangiocarcinoma and may aid in decision-making with respect to preoperative biliary drainage

Comparison of Total Tumor Volume, Size and Number of Colorectal Liver Metastases in Prediction of Survival in Patients after Liver Resection

Liver is the most common location of the colorectal cancer metastases occurrence. Liver resection is the only curative method of treatment. Unfortunately it is feasible only in 25% of patients with colorectal liver metastases, often because of the extensiveness of the disease. The aim of the study was to evaluate the predictive value of total tumor volume, size and number of colorectal liver metastases in patients treated with right hemihepatectomy. Material and methods. A retrospective analysis was performed in a group of 135 patients with colorectal liver metastases, who were treated with right hemihepatectomy. Total tumor volume was estimated based on the formula (4/3)πr3. Moreover, the study included an analysis of data on the number and size of tumors, radicality of the resection, time between primary tumor resection and liver resection, pre-operative blood serum concentration of carcinoembryonal antigen (CEA) and carcinoma antigen Ca19-9. The predictive value of the factors was evaluated by applying a Cox proportional hazards model and the area under the ROC curve. Results. The univariate analysis has shown the predictive value of size of the largest tumor (p=0.033; HR=1.065 per each cm) on the overall survival, however no predictive value of number of tumors (p=0.997; HR=1.000) and total tumor volume (p=0.212; HR=1.002) was observed. The multivariate analysis did not confirm the predictive value of the size of the largest tumor (p=0.141; HR=1.056). In the analysis of ROC curves, AUROC for the total tumor volume, the size of the largest tumor and the number of tumors were 0.629, 0.608, 0.520, respectively. Conclusions. Total tumor volume, size and number of liver metastases are not independent risk factors for the worse overall survival of patients with colorectal liver metastases treated with liver resection, therefore increased values of these factors should not be a contraindication for surgical treatmen

Skin Autofluorescence Measurement as Initial Assessment of Hepatic Parenchyma Quality in Patients Undergoing Liver Resection

Skin autofluorescence (SAF) can detect advanced glycation end products (AGEs) that accumulate in tissues over time. AGEs reflect patients’ general health, and their pathological accumulation has been associated with various diseases. This study aimed to determine whether its measurements can correlate with the liver parenchyma quality. This prospective study included 186 patients who underwent liver resections. Liver fibrosis and/or steatosis > 10% were found in almost 30% of the patients. ROC analysis for SAF revealed the optimal cutoff point of 2.4 AU as an independent predictor for macrovesicular steatosis ≥ 10% with an AUC of 0.629 (95% CI 0.538–0.721, p = 0.006), 59.9% sensitivity, 62.4% specificity, and positive (PPV) and negative (NPV) predictive values of 45.7% and 74.1%, respectively. The optimal cutoff point for liver fibrosis was 2.3 AU with an AUC of 0.613 (95% CI 0.519–0.708, p = 0.018), 67.3% sensitivity, 55.2% specificity, and PPV and NPV of 37.1% and 81.2%, respectively. In the multivariable logistic regression model, SAF ≥ 2.4 AU (OR 2.16; 95% CI 1.05–4.43; p = 0.036) and BMI (OR 1.21; 95% CI 1.10–1.33, p < 0.001) were independent predictors of macrovesicular steatosis ≥ 10%. SAF may enhance the available non-invasive methods of detecting hepatic steatosis and fibrosis in patients prior to liver resection

Aligned Contrastive Predictive Coding

International audienceWe investigate the possibility of forcing a self-supervised model trained using a contrastive predictive loss, to extract slowly varying latent representations. Rather than producing individual predictions for each of the future representations, the model emits a sequence of predictions shorter than the sequence of upcoming representations to which they will be aligned. In this way, the prediction network solves a simpler task of predicting the next symbols, but not their exact timing, while the encoding network is trained to produce piece-wise constant latent codes. We evaluate the model on a speech coding task and demonstrate that the proposed Aligned Contrastive Predictive Coding (ACPC) leads to higher linear phone prediction accuracy and lower ABX error rates, while being slightly faster to train due to the reduced number of prediction heads

Reoperacje z powodu krwawienia do jamy brzusznej po przeszczepieniu wątroby od dawcy zmarłego

Krwawienie do jamy otrzewnej jest jednym z najczęstszych powikłań chirurgicznych po transplantacji wątroby. Celem pracy była analiza czynników ryzyka krwawienia do jamy otrzewnej po transplantacji wątroby wymagającego reoperacji oraz zbadanie znaczenia tego powikłania w kontekście wczesnych i odległych wyników przeszczepień. Materiał i metodyka. Dane 603 przeszczepień wątroby wykonanych w Klinice Chirurgii Ogólnej, Transplantacyjnej i Wątroby w okresie od stycznia 2011 do września 2014 r. poddano analizie retrospektywnej. Do punktów końcowych badania należały: reoperacja z powodu krwawienia oraz zgon w okresie do 90 dni i od 90 dni do 3 lat po transplantacji. Wyniki. Reoperacje z powodu krwawienia wewnątrzbrzusznego konieczne były po 45 z 603 (7,5%) transplantacji. Niższe stężenie hemoglobiny przed operacją było jedynym niezależnym predykatorem reoperacji (p=0,002), z wartością odcięcia wynoszącą 11,3 g/dl. Odsetek śmiertelności pooperacyjnej w grupie biorców poddanych relaparotomii z powodu krwawienia był istotnie wyższy (15,6% vs 5,6%, p=0,008) w porównaniu do pozostałych chorych. Przeżycie ogólne od 90 dni do 3 lat po transplantacji w grupie chorych poddanych relaparotomii z powodu krwawienia (83,3%) było nieistotnie niższe w porównaniu do pozostałych chorych (92,2%, p=0,096). Niezależnie jednak od gorszych obserwowanych wyników transplantacji, analizy wieloczynnikowe nie potwierdziły istotnego wpływu relaparotomii wykonywanych z powodu krwawienia do jamy brzusznej na wczesną śmiertelność pooperacyjną (p=0,589) oraz 3-letnie przeżycie chorych (p=0,079). Wnioski. Interwencje chirurgiczne z powodu krwawienia do jamy brzusznej nie wpływają obecnie negatywnie na wczesne i odległe wyniki transplantacji wątroby. Przedoperacyjne stężenie hemoglobiny powyżej 11,3 g/dl jest czynnikiem istotnie zmniejszającym ryzyko wystąpienia tego powikłania, jednak przydatność kliniczna tego parametru wydaje się być wątpliwa

Extremes of Liver Transplantation for Hepatocellular Carcinoma

The aim of this retrospective observational study was to evaluate outcomes of patients with extremely advanced hepatocellular carcinoma (HCC) after liver transplantation. A total of 285 HCC patients after liver transplantation were screened for eligibility based on either intrahepatic dissemination (&ge;10 tumors) or macrovascular invasion. Tumor recurrence was the primary end-point. The study cohort comprised 26 patients. Median recurrence-free survival was 23.2 months with hepatitis B virus (HBV) infection (p = 0.038), higher AFP model score (p = 0.001), prolonged graft ischemia (p = 0.004), and younger donor age (p = 0.016) being significant risk factors. Median recurrence-free survival of HBV-negative and HBV-positive patients was 29.8 and 9.3 months, respectively (p = 0.053). In patients with macrovascular invasion, recurrence-free survival at 3 years was 46.3% with no specific predictors. Tumor size (p = 0.044), higher AFP model score (p = 0.019), prolonged graft ischemia (p = 0.016), and younger donor age (p = 0.041) were significant risk factors in patients with intrahepatic dissemination. Superior 3-year outcomes were observed in patients with intrahepatic dissemination and tumor size &lt;3.5 cm (83.3%, p = 0.027) and HBV-negative patients with ischemia &lt;9.7 h (85.7%, p = 0.028). In conclusion, patients with extremely advanced HCCs are remarkably heterogeneous with respect to their profile of tumor recurrence risk. This heterogeneity is largely driven by factors other than standard predictors of post-transplant HCC recurrence

Information Retrieval for ZeroSpeech 2021: The Submission by University of Wroclaw

International audienceWe present a number of low-resource approaches to the tasks of the Zero Resource Speech Challenge 2021. We build on the unsupervised representations of speech proposed by the organizers as a baseline, derived from CPC and clustered with the kmeans algorithm. We demonstrate that simple methods of refining those representations can narrow the gap, or even improve upon the solutions which use a high computational budget. The results lead to the conclusion that the CPC-derived representations are still too noisy for training language models, but stable enough for simpler forms of pattern matching and retrieva

Reoperations for intraabdominal bleeding following deceased donor liver transplantatio

Intraabdominal hemorrhage remains one of the most frequent surgical complications after liver transplantation. The aim of the study was to evaluate risk factors for intraabdominal bleeding requiring reoperation and to assess the relevance of the reoperations with respect to short- and long-term outcomes following liver transplantation. Material and methods. Data of 603 liver transplantations performed in the Department of General, Transplant and Liver Surgery in the period between January 2011 and September 2014 were analyzed retrospectively. Study end-points comprised: reoperation due to bleeding and death during the first 90 postoperative days and between 90 postoperative day and third post-transplant year. Results. Reoperations for intraabdominal bleeding were performed after 45 out of 603 (7.5%) transplantations. Low pre-transplant hemoglobin was the only independent predictor of reoperation (p=0.002) with the cut-off of 11.3 g/dl. Postoperative 90-day mortality was significantly higher in patients undergoing reoperation as compared to the remaining patients (15.6% vs 5.6%, p=0.008). Post-transplant survival from 90 days to 3 years was non-significantly lower in patients after reoperation for bleeding (83.3%) as compared to the remaining patients (92.2%, p=0.096). Nevertheless, multivariable analyses did not reveal any significant negative impact of reoperations for bleeding on short-term mortality (p=0.589) and 3-year survival (p=0.079). Conclusions. Surgical interventions due to postoperative intraabdominal hemorrhage do not appear to affect short- and long-term outcomes following liver transplantation. Preoperative hemoglobin concentration over 11.3 g/dl is associated with decreased risk of this complication, yet the clinical relevance of this phenomenon is doubtful