Serum sclerostin: the missing link in the bone-vessel cross-talk in hemodialysis patients?

We found for the first time that in maintenance hemodialysis patients, higher sclerostin serum level was associated with severe abdominal aortic calcification (AAC). In addition, cortical bone microarchitecture (density and thickness) assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) at tibia was also independently associated with severe AAC. These results suggest that sclerostin may be involved in the association of mineral and bone disorder with vascular calcification in hemodialysis patients.

INTRODUCTION

Severe abdominal aortic calcifications are predictive of high cardiovascular mortality in maintenance hemodialysis (MHD) patients. In patients with end-stage renal disease, a high aortic calcification score was associated with lower bone turnover on bone biopsies. Thus, we hypothesized that sclerostin, a Wnt pathway inhibitor mainly secreted by osteocytes and acting on osteoblasts to reduce bone formation, may be associated with vascular calcifications in MHD patients.

METHODS

Fifty-three MHD patients, aged 53 years [35-63] (median [Q1-Q3]) were included. Serum was sampled before the MHD session to assay sclerostin. Framingham score was computed and the abdominal aortic calcification (AAC) score was assessed according to Kauppila method on lateral spine imaging using DEXA. Tibia bone status was evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT). Patients were distributed into two groups according to their AAC score: patients with mild or without AAC (score below 6) versus patients with severe AAC (score of 6 and above).

RESULTS

In multivariate analysis, after adjustment on age, dialysis duration and diabetes, serum sclerostin and cortical thickness were independently associated with severe AAC (odds ratio (OR) = 1.43 for each 0.1 ng/mL increase [95 % confidence interval (CI) 1.10-1.83]; p = 0.006 and 0.16 for 1 SD increase [0.03-0.73]; p = 0.018, respectively). A second cardiovascular model adjusted on Framingham score and the above mentioned confounders showed similar results.

CONCLUSIONS

Elevated sclerostin serum level and poorer tibia cortical bone structure by HR-pQCT were positively and independently associated with higher odds of severe AAC in MHD patients. Serum sclerostin may become a biomarker of mineral and bone disorder and vascular risk in MHD patients.

A Small-Volume, Low-Cost, and Versatile Continuous Culture Device

BACKGROUND

Continuous culture devices can be used for various purposes such as establishing reproducible growth conditions or maintaining cell populations under a constant environment for long periods. However, commercially available instruments are expensive, were not designed to handle small volumes in the milliliter range, and can lack the flexibility required for the diverse experimental needs found in several laboratories.

METHODOLOGY/PRINCIPAL FINDINGS

We developed a versatile continuous culture system and provide detailed instructions as well as a graphical user interface software for potential users to assemble and operate their own instrument. Three culture chambers can be controlled simultaneously with the proposed configuration, and all components are readily available from various sources. We demonstrate that our continuous culture device can be used under different modes, and can easily be programmed to behave either as a turbidostat or chemostat. Addition of fresh medium to the culture vessel can be controlled by a real-time feedback loop or simply calibrated to deliver a defined volume. Furthermore, the selected light-emitting diode and photodetector enable the use of phenol red as a pH indicator, which can be used to indirectly monitor the bulk metabolic activity of a cell population rather than the turbidity.

CONCLUSIONS/SIGNIFICANCE

This affordable and customizable system will constitute a useful tool in many areas of biology such as microbial ecology as well as systems and synthetic biology.

Randomized, double-blind trial of anidulafungin versus fluconazole for prophylaxis of invasive fungal infections in high-risk liver transplant recipients

Invasive fungal infections (IFIs) are a common complication in liver transplant recipients. There are no previous randomized trials of an echinocandin for the prevention of IFIs in solid organ transplant recipients. In a randomized, double-blind trial conducted at University-affiliated transplant centers, 200 high-risk liver transplant recipients (100 patients per group) received either anidulafungin or fluconazole for antifungal prophylaxis. Randomization was stratified by Model for End-Stage Liver Disease score ≥30 and receipt of a pretransplant antifungal agent. The primary end point was IFI in a modified intent-to-treat analysis. The overall incidence of IFI was similar for the anidulafungin (5.1%) and the fluconazole groups (8.0%) (OR 0.61, 95% CI 0.19-1.94, p = 0.40). However, anidulafungin prophylaxis was associated with less Aspergillus colonization or infection (3% vs. 9%, p = 0.08), lower breakthrough IFIs among patients who had received pretransplant fluconazole (0% vs. 27%, p = 0.07), and fewer cases of antifungal resistance (no cases vs. 5 cases). Both drugs were well-tolerated. Graft rejection, fungal-free survival, and mortality were similar for both groups. Thus, anidulafungin and fluconazole have similar efficacy for antifungal prophylaxis in most liver transplant recipients. Anidulafungin may be beneficial if the patient has an increased risk for Aspergillus infection or received fluconazole before transplantation.

Preconditioning for edge-preserving image super resolution

We propose a simple preconditioning method for accelerating the solution of edge-preserving image super-resolution (SR) problems in which a linear shift-invariant point spread function is employed. Our technique involves reordering the high-resolution (HR) pixels in a similar manner to what is done in preconditioning methods for quadratic SR formulations. However, due to the edge preserving requirements, the Hessian matrix of the cost function varies during the minimization process. We develop an efficient update scheme for the preconditioner in order to cope with this situation. Unlike some other acceleration strategies that round the displacement values between the low-resolution (LR) images on the HR grid, the proposed method does not sacrifice the optimality of the observation model. In addition, we describe a technique for preconditioning SR problems involving rational magnification factors. The use of such factors is motivated in part by the fact that, under certain circumstances, optimal SR zooms are nonintegers. We show that, by reordering the pixels of the LR images, the structure of the problem to solve is modified in such a way that preconditioners based on circulant operators can be used.

The clinical presentation and prognostic factors for intrahepatic and extrahepatic cholangiocarcinoma in a tertiary care centre

BACKGROUND

The incidence of cholangiocarcinoma is rising. Accurate predictors of survival at diagnosis are not well defined.

AIM

To clarify the clinical presentation and prognostic factors of intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma in a contemporary cohort of patients.

METHODS

Records for consecutive patients at the University of Michigan hospital diagnosed with cholangiocarcinoma between January 2003 and April 2008 were reviewed.

RESULTS

In all, 136 patients had cholangiocarcinoma (79 intra- and 57 extrahepatic cholangiocarcinoma). Median survival was 27.3 months-25.8 months for intrahepatic cholangiocarcinoma and 30.3 months for extrahepatic cholangiocarcinoma. Independent predictors of mortality at presentation on multivariate analysis were elevated bilirubin level (HR 1.04, 95%CI 1.01-1.07), CA 19-9 levels >100 U/mL (HR 1.90, 95%CI 1.17-3.08) and stage of disease (HR 1.51, 95%CI 1.16-1.96). After adjusting for baseline prognostic factors, surgical therapy was associated with improved survival (HR 0.48; 95% CI 0.26-0.88). There were no significant differences regarding clinical presentation, disease stage (P = 0.98), and survival (P = 0.51) between intra- and extrahepatic cholangiocarcinoma.

CONCLUSIONS

Survival for cholangiocarcinoma remains poor with no significant difference in outcomes between intra- and extrahepatic cholangiocarcinoma. Stage of disease, bilirubin level and CA 19-9 level are important prognostic factors at presentation. Surgical therapy provides similar efficacy for both tumours when adjusted for other prognostic variables.

Predicting timothy mineral concentrations, dietary cation-anion difference, and grass tetany index by near-infrared reflectance spectroscopy

The mineral concentration of forage grasses plays a significant role in 2 metabolic disorders in dairy cattle production, namely, hypocalcemia (milk fever) and hypomagnesemia (grass tetany). Risks of occurrence of these 2 metabolic disorders can be evaluated by determining the dietary cation-anion difference (DCAD) and the grass tetany (GT) index of forages and specific rations. The objective of this study was to evaluate the feasibility of predicting timothy (Phleum pratense L.) mineral concentrations of Na, K, Ca, Mg, Cl, S, and P, the DCAD, and the GT index by near-infrared reflectance spectroscopy (NIRS). Timothy samples (n = 1,108) were scanned using NIRS and analyzed for the concentration of 7 mineral elements. Calculations of the DCAD were made using 3 different formulas, and the GT index was also calculated. Samples were divided into calibration (n = 240) and validation (n = 868) sets. The calibration, cross-validation, and prediction for mineral concentrations, the DCAD, and the GT index were performed using modified partial least squares regression. Concentrations of K, Ca, Mg, Cl, and P were successfully predicted with coefficients of determination of prediction (R(P)2) of 0.69 to 0.92 and coefficients of variation of prediction (CV(P)) ranging from 6.6 to 11.4%. The prediction of Na and S concentrations failed, with respective R(P)2 of 0.58 and 0.53 and CV(P) of 82.2 and 12.9%. The 3 calculated DCAD and the GT index were predicted successfully, with R(P)2 >0.90 and CV(P) <20%. Our results confirm the feasibility of using NIRS to predict K, Ca, Mg, and Cl concentrations, as well as the DCAD and the GT index, in timothy.

Impact of model for end-stage liver disease on patient survival and disease-free survival in patients receiving liver transplantation for hepatocellular carcinoma

We combined data from two transplant centers to determine the impact of the model for end-stage liver disease (MELD) allocation system on outcomes in patients undergoing liver transplantation for hepatocellular carcinoma (HCC). We compared 55 patients listed before MELD to 117 patients in the MELD era. Patients before MELD were less likely to receive a transplant (67% vs 91%) and waited a median of 127 days vs 20 days (P < .001). On an intention to treat (ITT) basis, the 1-, 3-, and 5-year survivals for patients before MELD were 79%, 60%, and 48%, and in the MELD era were 84%, 73%, and 73% (P = .055). On an ITT basis, the 1-, 3-, and 5-year tumor-free survivals before MELD were 58%, 58%, and 55% vs 83%, 74%, and 70% in the MELD era (P = .018). In patients who received a transplant, however, there were no differences in overall or tumor-free survival. In these patients, the 1-, 3-, and 5-year patient survivals were 92%, 84%, and 67% before MELD, and 90%, 81%, and 81% in the MELD era (P = .57). In transplanted patients, the 1-, 3-, and 5-year tumor-free survivals before MELD were 88%, 88%, and 83% vs 92%, 83%, and 78% in the MELD era (P = .403). On explant, patients listed before MELD had lower grade tumors (P = .046). We concluded that patients with HCC listed in the MELD era had higher and more rapid rates of transplantation with improvements in survival. However, the more efficacious rates of transplantation did not result in lower rates of tumor recurrence.

Incidental hepatocellular carcinoma after liver transplantation: population characteristics and outcomes

We combined data from two liver transplant centers to determine the tumor characteristics and outcomes of 51 patients transplanted with incidental hepatocellular carcinoma (iHCC) compared with 143 patients transplanted for previously known HCC (pkHCC). There were no differences in age, gender, or frequency of hepatitis C infection. Patients with iHCC were more likely to be African-American (22% vs 10%; P = .016), more likely to be screened by ultrasound (38% vs 9%; P < .001), had a lower alpha-fetoprotein (83.9 +/- 258.1 vs 572.4 +/- 2376.4 ng/mL; P = .005), and had a higher model for end-stage liver disease (MELD) score (14.3 +/- 4.1 vs 11.8 +/- 4.7; P < .001). The liver explants of patients with iHCC had smaller total tumor burden than patients with pkHCC (3.1 +/- 3.5 vs 4.1 +/- 2.6 cm; P < .001), but a similar percentage of single lesions (66% vs 65%) and tumors that met Milan criteria (76% vs 65%). Patients with iHCC had 1-, 3-, and 5-year survivals of 78%, 67%, and 58%, and 1-, 3-, and 5-year recurrence-free survivals of 90%, 87%, and 87% compared with the 1-, 3-, and 5-year survivals of 90%, 82%, and 70%, and the 1-, 3-, and 5-year tumor-free survivals of 91%, 84%, and 78% in patients with pkHCC. We concluded that patients with iHCC were more likely to be African-American, to be screened by ultrasound, to have a lower alpha-fetoprotein, and a higher MELD score. Ultrasound is not a sensitive modality for screening patients for HCC. Patients with iHCC do not have an advantage in survival over those with pkHCC.

Incidental hepatocellular carcinoma after liver transplantation: population characteristics and outcomes

We combined data from two liver transplant centers to determine the tumor characteristics and outcomes of 51 patients transplanted with incidental hepatocellular carcinoma (iHCC) compared with 143 patients transplanted for previously known HCC (pkHCC). There were no differences in age, gender, or frequency of hepatitis C infection. Patients with iHCC were more likely to be African-American (22% vs 10%; P = .016), more likely to be screened by ultrasound (38% vs 9%; P < .001), had a lower alpha-fetoprotein (83.9 +/- 258.1 vs 572.4 +/- 2376.4 ng/mL; P = .005), and had a higher model for end-stage liver disease (MELD) score (14.3 +/- 4.1 vs 11.8 +/- 4.7; P < .001). The liver explants of patients with iHCC had smaller total tumor burden than patients with pkHCC (3.1 +/- 3.5 vs 4.1 +/- 2.6 cm; P < .001), but a similar percentage of single lesions (66% vs 65%) and tumors that met Milan criteria (76% vs 65%). Patients with iHCC had 1-, 3-, and 5-year survivals of 78%, 67%, and 58%, and 1-, 3-, and 5-year recurrence-free survivals of 90%, 87%, and 87% compared with the 1-, 3-, and 5-year survivals of 90%, 82%, and 70%, and the 1-, 3-, and 5-year tumor-free survivals of 91%, 84%, and 78% in patients with pkHCC. We concluded that patients with iHCC were more likely to be African-American, to be screened by ultrasound, to have a lower alpha-fetoprotein, and a higher MELD score. Ultrasound is not a sensitive modality for screening patients for HCC. Patients with iHCC do not have an advantage in survival over those with pkHCC.

Delayed harvest affects mineral and NDF concentrations, and digestibility of timothy

A 1-wk delay after late heading in the harvest of timothy spring growth reduced dietary cation-anion difference (-17%), in vitro digestibilities of dry matter (-7%) and neutral detergent fiber (-10%), and increased neutral detergent fiber concentration (+5%). In summer regrowth, the harvest delay tended to have similar effects, but variations (1-6%) were smaller. Key words: Nutritive value, stages of development, Phleum pratense L., metabolic disorders