Gd-EOB-DTPA-enhanced T1 relaxometry for assessment of liver function determined by real-time 13C-methacetin breath test

OBJECTIVES

To determine whether liver function as determined by intravenous administration of ¹³C-methacetin and continuous real-time breath analysis can be estimated quantitatively from gadoxetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) relaxometry.

METHODS

Sixty-six patients underwent a ¹³C-methacetin breath test (¹³C-MBT) for evaluation of liver function and Gd-EOB-DTPA-enhanced T1-relaxometry at 3 T. A transverse 3D VIBE sequence with an inline T1 calculation based on variable flip angles was acquired prior to (T1 pre) and 20 min post-Gd-EOB-DTPA (T1 post) administration. The reduction rate of T1 relaxation time (rrT1) and T1 relaxation velocity index (∆R1) between pre- and post-contrast images was evaluated. ¹³C-MBT values were correlated with T1_post, ∆R1 and rrT1, providing an MRI-based estimated ¹³C-MBT value. The interobserver reliability was assessed by determining the intraclass correlation coefficient (ICC).

RESULTS

Stratified by three different categories of ¹³C-MBT readouts, there was a constant increase of T1 post with increasing progression of diminished liver function (p ≤ 0.030) and a constant significant decrease of ∆R1 (p ≤ 0.025) and rrT1 (p < 0.018) with progression of liver damage as assessed by ¹³C-methacetin breath analysis. ICC for all T1 relaxation values and indices was excellent (> 0.88). A simple regression model showed a log-linear correlation of ¹³C-MBT values with T1_post (r = 0.57; p < 0.001), ∆R1 (r = 0.59; p < 0.001) and rrT1 (r = 0.70; p < 0.001).

CONCLUSION

Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MR relaxometry.

KEY POINTS

• Gd-EOB-DTPA-enhanced T1 relaxometry quantifies liver function • Gd-EOB-DTPA-enhanced MR relaxometry may provide parameters for assessing liver function before surgery • Gd-EOB-DTPA-enhanced MR relaxometry may be useful for monitoring liver disease progression • Gd-EOB-DTPA-enhanced MR relaxometry has the potential to become a novel liver function index.

Predicting Early Viral Control under Direct-Acting Antiviral Therapy for Chronic Hepatitis C Virus Using Pretreatment Immunological Markers

Recent introduction of all-oral direct-acting antiviral (DAA) treatment has revolutionized care of patients with chronic hepatitis C virus (HCV) infection. Regrettably, the high cost of DAA treatment is burdensome for healthcare systems and may be prohibitive for some patients who would otherwise benefit. Understanding how patient-related factors influence individual responses to DAA treatment may lead to more efficient prescribing. In this observational study, patients with chronic HCV infection were comprehensively monitored by flow cytometry to identify pretreatment immunological variables that predicted HCV RNA negativity within 4 weeks of commencing DAA treatment. Twenty-three patients [genotype 1a (n = 10), 1b (n = 9), and 3 (n = 4)] were treated with daclatasvir plus sofosbuvir (SOF) (n = 15), ledipasvir plus SOF (n = 4), or ritonavir-boosted paritaprevir, ombitasvir, and dasabuvir (n = 4). DAA treatment most prominently altered the distribution of CD8+ memory T cell subsets. Knowing only pretreatment frequencies of CD3+ and naive CD8+ T cells allowed correct classification of 83% of patients as "fast" (HCV RNA-negative by 4 weeks) or "slow" responders. In a prospective cohort, these parameters correctly classified 90% of patients. Slow responders exhibited higher frequencies of CD3+ T cells, CD8+ TEM cells, and CD5high CD27- CD57+ CD8+ chronically activated T cells, which is attributed to bystander hyperactivation of virus-non-specific CD8+ T cells. Taken together, non-specific, systemic CD8+ T cell activation predicted a longer time to viral clearance. This discovery allows pretreatment identification of individuals who may not require a full 12-week course of DAA therapy; in turn, this could lead to individualized prescribing and more efficient resource allocation.

[Radiation cystitis : Pathophysiology and treatment]

Radiation cystitis (RC) is a common side-effect of radiation to the pelvis. Their clinical appearance as well as their degree of expression is manifold, as are the therapeutic options. However, in the absence of randomized examinations, recommendations are difficult. We differentiate between oral, systemic therapies, intravesical instillations and interventions as well as interventional, radiological and, as an ultima ratio, surgical treatments. This article provides an overview of the different treatment options with particular emphasis on the conservative-interventional therapy options.

[Expert recommendations: Hepatitis C and transplantation]

With the approval of new direct acting antiviral agents (DAA), therapeutic options for patients with chronic hepatitis C virus (HCV) infection are now generally available before and after liver transplantation (LT). Interferon-free DAA regimens are highly effective therapies and provide a good safety profile. However, the body of clinical evidence in this patient population is limited and the best treatment strategies for patients on the waiting list with (de)compensated cirrhosis and after LT are not well defined. The following recommendations for antiviral therapy in the context of LT are based on the currently available literature and clinical experience of experts in the field, and have been discussed in an expert meeting. The aim of this article is to guide clinicians in the decision making when treating patients before and after LT with DAAs.

Immune tolerance against HBV can be overcome in HBV transgenic mice by immunization with dendritic cells pulsed by HBVsvp

In chronic Hepatitis B Virus (HBV) infection the function of dendritic cells (DC), T- and B-cells is impaired. DC vaccination is an option to overcome this. DC pulsed in vitro with HBV sub viral particles (HBVsvp) and used to immunize mice can activate HBV directed humoral and cellular immune responses. In the present study we vaccinated HBV transgenic mice as a model for chronic HBV infection and observed humoral and cellular immune responses. In these mice, the lacking immune response against HBV is mainly due to peripheral tolerance. HBVsvp, together with LPS as a co-activating molecule, were used for pulsing and in vitro activation of DC. HBV transgenic mice were injected with pulsed DC two times. Four weeks after DC vaccination humoral and cellular immune responses, viral antigen levels and liver histology were analyzed. DC vaccinated HBV-transgenic mice developed a strong HBV specific antibody and T-cell response after DC vaccination. Neither circulating HBV antigen levels nor viremia, however, were controlled. No liver damage was observed. These results demonstrate that in vitro activation of DC and loading with HBVsvp can overcome tolerance against HBV and reactivate B- and T-cell responses in HBV transgenic mice, but were not sufficient to lead to virus control in these mice. Vaccination using DC, the key players of cellular and humoral immunity, after in vitro reactivation promises to break tolerance against HBV and may help patients with chronic hepatitis B to clear the infection.

Vaccination with dendritic cells pulsed with hepatitis C pseudo particles induces specific immune responses in mice

AIM

To explore dendritic cells (DCs) multiple functions in immune modulation.

METHODS

We used bone-marrow derived dendritic cells from BALB/c mice pulsed with pseudo particles from the hepatitis C virus to vaccinate naive BALB/c mice. Hepatitis C virus (HCV) pseudo particles consist of the genotype 1b derived envelope proteins E1 and E2, covering a non-HCV core structure. Thus, not a single epitope, but the whole "viral surface" induces immunogenicity. For vaccination, mature and activated DC were injected subcutaneously twice.

RESULTS

Humoral and cellular immune responses measured by enzyme-linked immunosorbent assay and interferon-gamma enzyme-linked immunosorbent spot test showed antibody production as well as T-cells directed against HCV. Furthermore, T-cell responses confirmed two highly immunogenic regions in E1 and E2 outside the hypervariable region 1.

CONCLUSION

Our results indicate dendritic cells as a promising vaccination model for HCV infection that should be evaluated further.

Prognostic value of standard parameters as predictors for long-term renal replacement therapy after liver transplantation

Chronic kidney disease has become increasingly prevalent after liver transplantation (LTPL) because outcome and survival rates have improved. Chronic kidney insufficiency is most likely associated with increased morbidity and mortality. The challenge is to identify patients who will be in need of long-term renal replacement therapy (RRT) after LTPL. We analyzed 208 liver transplant recipients with respect to mortality, associated laboratory values, underlying liver disease, immunosuppressive protocol and the need for RRT. Long-term RRT was defined by the need for RRT 3 months after LTPL. Altogether, 5.8% of the surviving study patients remained in need of RRT 3 months after LTPL. All of these patients continued to need RRT throughout the study period (2 years). The need for RRT significantly increased the 2-year mortality rate 4.3-fold, from 15.4 to 66.7% (p = 0.004). Comparison of laboratory and clinical parameters at the time of LTPL revealed no significant differences for creatinine, albumin and MDRD between patients undergoing hemodialysis 3 months after LTPL and patients without RRT. Comparing mean urea, a difference was observed. However, multivariate regression analyses using easy-to-observe demographic or laboratory parameters failed to generate a model to predict the need for RRT after LTPL. In addition, a comparison of underlying liver disease and immunosuppressive regimes identified no significant differences. Taken together, patients who were on hemodialysis 3 months after LTPL were also on hemodialysis 2 years after LTPL or until death. RRT 3 months after LTPL may predict the risk for chronic renal insufficiency and is associated with significantly increased mortality.

Activation of natural killer cells by hepatitis C virus particles in vitro

Little is known about the ability of hepatitis C virus (HCV) to alter early innate immune responses in infected patients. Previous studies have shown that natural killer (NK) cells are functionally impaired after interaction of recombinant HCV glycoprotein E2 with the co-stimulatory CD81 molecule in vitro; however, the functional consequences of a prolonged contact of NK cells with HCV particles have remained unclear. We have examined the phenotypes of purified, interleukin-2-activated NK cells from healthy donors and HCV genotype 1b patients after culture for 5 days with HCV pseudoparticles (HCVpp) and serum samples containing HCV genotype 1b. NK cells from healthy donors and chronic HCV patients were found to up-regulate receptors associated with activation (NKp46, NKp44, NKp30, NKG2D), while NK receptors from the killer cell immunoglobulin-like receptor family (KIR/CD158), predominantly having an inhibitory function, were significantly down-modulated after culture in the presence of HCV particles compared with control cultures of NK cells. HCV-infected sera and HCVpp elicited significantly higher secretion of the NK effector lymphokines interferon-γ and tumour necrosis factor-α. Furthermore, HCV stimulated the cytotoxic potential of NK cells from normal donors and patients. The enhanced activation of NK cells after prolonged culture with HCVpp or HCV-containing sera for 5 days suggests that these innate effector cells may play an important role in viral control during early phases of HCV infection.

Dendritic cells can effectively be pulsed by HBVsvp and induce specific immune reactions in mice

Eradication of chronic Hepatitis B virus (HBV) infection, marked by HBs seroconversion, is very rarely achieved by treatment with nucleoside and nucleotide analogs. Therapeutic cell based approaches, like interferon therapy, have a higher chance of seroconversion. Dendritic cells (DC) are key players in the cellular immune response and have been shown to play an important role in controlling HBV infection. In this study, the potential of ex vivo activated DC to induce specific immune responses against HBV was examined. DC derived from bone-marrow of BALB/c or C56BL/6 mice were pulsed with HBV subviral particles (HBVsvp), derived from the HepG2.2.15 cell line. HepG2.2.15 produces subviral particles consisting of the HBc and HBs proteins. Thus, the entire "viral surface" is presented to DC to induce an immune reaction. In vitro pulsation with HBVsvp successfully activated bone-marrow derived DC, demonstrated by FACS analysis showing increased MHCII, CD 86 and CCR-7. Immunization of mice, via subcutaneous injection of the activated DC, induced HBV specific immune reactions which were measured by ELISA, ELISPOT and T-cell proliferation analysis. Vaccination with ex vivo activated DC may be a promising tool for therapeutic or prophylactic approaches against the Hepatitis B virus.

Assembly and export determine the intracellular distribution of hepatitis B virus core protein subunits

Little is known about the parameters and factors that determine the intracellular distribution of the hepatitis B virus core protein (HBc). In order to study HBc in living cells, HBc was tagged with green fluorescent protein (GFP). Being assembly-incompetent, the GFP-fusion protein was distributed equally throughout the cell. Mutational inactivation of known serine-phosphorylation sites within the C-terminal region led to predominantly intranuclear localization. Phosphorylation of these targets, presumably by an SR domain protein kinase, resulted in a predominantly cytoplasmic localization, which suggests active cytoplasmic export or retention. The phosphoserine itself, and not its negative charge, appears essential for the underlying mechanism. In addition, the arginine-rich, protamine-like domain surrounding these phosphorylation sites does not function as the dominant nuclear-localization signal, as had been assumed previously, because neither deleting nor altering these sequences led to a change in intracellular HBc subunit distribution. Restoring the capability of the fusion protein to form capsids by co-assembly with assembly-competent, sterically uncompromised HBc subunits provided a second assay that gave insight into the effects resulting from capsid formation. Assembly was found to be the dominant factor in the cytoplasmic retention of the GFP-HBc fusion protein. Furthermore, the stability of these empty capsids was influenced by the cell-cycle inhibitor nocodazole. Thus, the intracellular distribution of HBc is dominated by cytoplasmic assembly, which is supported by the active nuclear export of HBc subunits, and modulated during the cell cycle by the instability of capsids.

Low levels of prothrombin time (INR) and platelets do not increase the risk of significant bleeding when placing central venous catheters

BACKGROUND AND PURPOSE

Central venous catheters are frequently placed in intensive care medicine for multiple indications. The risk of severe bleeding after cannulation is considered to be increased in patients with abnormal coagulation, common in critically ill patients.

PATIENTS AND METHODS

This open prospective trial, performed at two medical intensive care units and one hematology intermediate care ward, investigated whether insertion of a central venous catheter in patients with coagulopathy (prothrombin time <or= 50% [International Normalized Ratio, INR, >or= 1.5] and/or platelets <or= 50 x 10(9)/l) bears an increased risk of bleeding.

RESULTS

In 196 patients with and without severe disorders of hemostasis, no significant difference in decrease of hemoglobin after catheter placement was observed. In addition, no correlation between a significant drop in hemoglobin and increased levels of creatinine or urea was seen. Mechanical complications were similar in frequency compared to previous publications.

CONCLUSION

These findings demonstrate that coagulation disorders with altered prothrombin time (INR) or platelets do not increase the risk of significant bleeding when inserting a central venous catheter. Therefore, the prophylactic correction of coagulation by transfusion of blood products or coagulation factors is not necessary before central venous catheter insertion.

Percutaneous liver biopsy: retrospective study over 15 years comparing 287 inpatients with 428 outpatients

BACKGROUND AND AIM

Liver histology still represents the gold standard for the assessment of liver inflammation, necrosis, and fibrosis. The least cumbersome way of obtaining liver tissue is percutaneous liver biopsy. The aim of this retrospective study was to compare the complications following liver biopsy in in- and outpatients and to evaluate for which patients the benefit from liver biopsy is highest.

METHODS

All patients undergoing percutaneous liver biopsy at a teaching hospital between January 1990 and April 2005 were evaluated for indications, complications and impact of histology.

RESULTS

Liver biopsy was performed in 287 inpatients and 428 outpatients with a success rate of 99.4%. The total complication rate was 6.3% in inpatients and 11% in outpatients. Only two major complications, but no deaths occurred. Pain was the main complication, especially in young patients with chronic viral hepatitis. Despite normal alanine aminotransferase (ALT) levels advanced liver fibrosis was found in 9.3%, 2.6%, and 5.4% of all patients with HBV-, HCV infection, and non viral liver diseases, respectively. In 3% of all patients evaluated a previously unrecognized second liver disease was found. In 21.4% of the patients alkaline phosphatase (AP) levels were elevated, and in more than 90% of these patients liver biopsy led to the final diagnosis.

CONCLUSION

Liver biopsy is safe in in- and outpatients. Biopsy is particularly helpful in patients suspected of having liver disease in spite of normal ALT levels or in patients exhibiting unexplained elevated AP levels.

Acute cholecystitis - early laparoskopic surgery versus antibiotic therapy and delayed elective cholecystectomy: ACDC-study

BACKGROUND

Acute cholecystitis occurs frequently in the elderly and in patients with gall stones. Most cases of severe or recurrent cholecystitis eventually require surgery, usually laparoscopic cholecystectomy in the Western World. It is unclear whether an initial, conservative approach with antibiotic and symptomatic therapy followed by delayed elective surgery would result in better morbidity and outcome than immediate surgery. At present, treatment is generally determined by whether the patient first sees a surgeon or a gastroenterologist. We wish to investigate whether both approaches are equivalent. The primary endpoint is the morbidity until day 75 after inclusion into the study.

DESIGN

A multicenter, prospective, randomized non-blinded study to compare treatment outcome, complications and 75-day morbidity in patients with acute cholecystitis randomized to laparoscopic cholecystectomy within 24 hours of symptom onset or antibiotic treatment with moxifloxacin and subsequent elective cholecystectomy. For consistency in both arms moxifloxacin, a fluorquinolone with broad spectrum of activity and high bile concentration is used as antibiotic.

DURATION

October 2006 - November 2008.

ORGANISATION/RESPONSIBILITY

The trial was planned and is being conducted and analysed by the Departments of Gastroenterology and General Surgery at the University Hospital of Heidelberg according to the ethical, regulatory and scientific principles governing clinical research as set out in the Declaration of Helsinki (1989) and the Good Clinical Practice guideline (GCP).

TRIAL REGISTRATION

ClinicalTrials.gov NCT00447304.

Treatment of hepatitis C virus infection

Acute and chronic hepatitis C virus (HCV) infection remains a serious health problem worldwide, however, there has been advancement in the treatment of HCV infection due to standard treatment using pegylated interferon and ribavirin. The literature indicates that therapy for HCV is becoming more individualized. In addition to considering genotype and viral RNA levels before treatment, achievement of an early virologic response (EVR) and a rapid virologic response (RVR) is now possible during therapy. Moreover, problem patients, such as non-responders, relapsers, HIV or HBV co-infected patients, patients with liver cirrhosis, and pre- or post-liver transplantation patients are an increasing fraction of the patients requiring treatment. This article reviews the literature regarding standard treatments and problem patients with acute and chronic HCV infection. It also includes discussion on contraindications and side effects of treatment with interferon and ribavirin, as well as new drug development.

Are heat stroke and physical exhaustion underestimated causes of acute hepatic failure?

While cardiopulmonary symptoms are common in patients undergoing classical or, due to physical exercise, exertional heat stroke, the failure of other organs is a rarely described phenomenon. Here we present two cases of acute hepatic failure, one due to classic heat shock, while the other occurred while the patient was doing a marathon-type running. Both cases presented with very high transaminases and significantly elevated international normalized ratio (INR). No other causes for liver failure could be identified but physical exhaustion and hyperthermia.

Multigenotype HCV-NS3 recombinant vaccinia viruses as a model for evaluation of cross-genotype immunity induced by HCV vaccines in the mouse

Surrogate infections with HCV-recombinant vaccinia viruses (HCV-rVV) are a standard method to test the efficacy of hepatitis C virus (HCV) vaccine candidates in the mouse model. We established a panel of 16 HCV-rVV expressing the nonstructural protein 3 (NS3) of HCV genotypes 1a, 1b, 2, 3 and 4. Mice immunized with recombinant NS3 protein derived from HCV genotype 1b were challenged with the rVV. rVV-titers decreased up to 54-fold after subtype 1b challenge and up to 8.5-fold after subtype 1a challenge. No change was detected for genotype 2, 3, or 4. Our model is a convenient and reliable tool to analyze the induction of cross-genotype immunity by experimental vaccination of mice.