A peptide extension dictates IgM assembly.

Professional secretory cells can produce large amounts of high-quality complex molecules, including IgM antibodies. Owing to their multivalency, polymeric IgM antibodies provide an efficient first-line of defense against pathogens. To decipher the mechanisms of IgM assembly, we investigated its biosynthesis in living cells and faithfully reconstituted the underlying processes in vitro. We find that a conserved peptide extension at the C-terminal end of the IgM heavy (Ig-µ) chains, termed the tailpiece, is necessary and sufficient to establish the correct geometry. Alanine scanning revealed that hydrophobic amino acids in the first half of the tailpiece contain essential information for generating the correct topology. Assembly is triggered by the formation of a disulfide bond linking two tailpieces. This induces conformational changes in the tailpiece and the adjacent domain, which drive further polymerization. Thus, the biogenesis of large and topologically challenging IgM complexes is dictated by a local conformational switch in a peptide extension.

Treatment-failure to direct antiviral HCV regimens in real world: frequency, patient characteristics and rescue therapy - data from the German hepatitis C registry (DHC-R).

BACKGROUND: Virologic failure to approved combinations of direct antiviral agents (DAA) in patients with chronic hepatitis C virus (HCV) infection is rare. Mostly it involves difficult to treat patients with advanced liver disease and prior interferon-experience. Before approval of VOX/VEL/SOF, a restricted number of patients received rescue treatment, and the choice of DAA combinations for re-treatment were selected on an individual basis. In the present analysis, patient characteristics and rescue-regimens after virologic failure mainly based on first generation DAAs are described. PATIENTS AND METHODS: Data were obtained from the German Hepatitis C-Registry (DHC-R), which is a national multicenter real-world cohort currently including about 16 500 patients recruited by more than 250 centers. The present analysis is based on 6683 patients who initiated a DAA therapy and for whom follow-up data (per-protocol analysis) were available. RESULTS: Among the patients, 188 (2.8 %) experienced a virologic relapse. Compared to SVR-patients, relapse patients were significantly more often male (77.7 % versus 56.9 %, respectively, p < 0.001), showed cirrhosis significantly more (48.4 % versus 28.1 %, respectively, p < 0.001) and a prior interferon-containing therapy (46.3 % versus 39.0 %, respectively, p = 0.049). The majority of patients who relapsed were infected with genotype 1 (47.4 %) followed by genotype 3 (29.8 %), and 95 relapse patients started DAA re-treatment. Characteristics of patients with rescue-treatment are similar to these of patients with relapse after initial DAA treatment. Thirty-one of 39 patients with complete follow-up data achieved SVR (79.5 %), and 8 patients had a relapse again (20.5 %). Patients who received rescue treatment including a new DAA class according to guidelines, except patients who received VOX/VEL/SOF, showed higher SVR rates than the entire group (21/25, 84 %). All patients who received VOX/VEL/SOF achieved SVR (n = 4, 100 %). CONCLUSIONS: Patients with failure with DAA combination therapies are a difficult but urgent to treat population with the frequent presence of cirrhosis and prior treatment failure with interferon-based therapies. Rescue therapy with inclusion of a new DAA class leads to high SVR rates, but multiple targeted therapy with VOX/VEL/SOF seems to be most effective.

A chemical compound inhibiting the Aha1-Hsp90 chaperone complex.

The eukaryotic Hsp90 chaperone machinery comprises many co-chaperones and regulates the conformation of hundreds of cytosolic client proteins. Therefore, it is not surprising that the Hsp90 machinery has become an attractive therapeutic target for diseases such as cancer. The compounds used so far to target this machinery affect the entire Hsp90 system. However, it would be desirable to achieve a more selective targeting of Hsp90-co-chaperone complexes. To test this concept, in this-proof-of-principle study, we screened for modulators of the interaction between Hsp90 and its co-chaperone Aha1, which accelerates the ATPase activity of Hsp90. A FRET-based assay that monitored Aha1 binding to Hsp90 enabled identification of several chemical compounds modulating the effect of Aha1 on Hsp90 activity. We found that one of these inhibitors can abrogate the Aha1-induced ATPase stimulation of Hsp90 without significantly affecting Hsp90 ATPase activity in the absence of Aha1. NMR spectroscopy revealed that this inhibitory compound binds the N-terminal domain of Hsp90 close to its ATP-binding site and overlapping with a transient Aha1-interaction site. We also noted that this inhibitor does not dissociate the Aha1-Hsp90 complex but prevents the specific interaction with the N-terminal domain of Hsp90 required for catalysis. In consequence, the inhibitor affected the activation and processing of Hsp90-Aha1-dependent client proteins in vivo We conclude that it is possible to abrogate a specific co-chaperone function of Hsp90 without inhibiting the entire Hsp90 machinery. This concept may also hold true for other co-chaperones of Hsp90.

Treatment of HCV genotype 2 with sofosbuvir and ribavirin results in lower sustained virological response rates in real life than expected from clinical trials.

BACKGROUND AND AIMS: Hepatitis C virus (HCV) infections with genotype 2 (GT2) are generally considered as easy to treat. The current standard therapy is 12 weeks of sofosbuvir and ribavirin. However, sustained virological response (SVR) rates varied substantially in distinct subgroups. Therefore, re-assessing the efficacy of interferon-free therapy in cohorts with larger patient numbers is warranted. METHODS: The German Hepatitis C registry is a national multicenter cohort. Patients are treated at the discretion of the physician. Data are collected by a web-based data system and confirmed by plausibility checks and on-site monitoring. RESULTS: A total of 265 (4.3%) of 6034 patients enrolled in the registry were infected with GT2, and 236 had initiated treatment (60% males, 98% Caucasian, median age 54 years). Treatment with sofosbuvir and ribavirin for 12 weeks achieved SVR at week 12 post-treatment (SVR12) in 136/164 (83%) patients. SVR12 rates for this regimen were 80% (35/44) in treatment-experienced patients, 74% (20/27) in cirrhotics and 75% (21/28) in patients with HCV-RNA ≥6 million IU/mL. The overall SVR rate in patients treated with sofosbuvir/ribavirin 12 weeks per protocol (PP), excluding therapy discontinuation or lost to follow-up, was 135/151 (89%). PP SVR12 rates were 91% for treatment naïve, 83% for cirrhotic and 80% for treatment-experienced patients respectively. CONCLUSIONS: In this large GT2 cohort, sofosbuvir and ribavirin for 12 weeks achieved lower SVR rates compared to treatment outcomes expected from phase 3 trials. These findings highlight the need for establishing alternative treatment strategies for GT2 patients, especially in patients with unfavourable outcome factors.

Effectiveness and Safety of Tenofovir Disoproxil Fumarate in Chronic Hepatitis B: A 3-Year Prospective Field Practice Study in Germany.

BACKGROUND AND AIMS: Multiple clinical trials have demonstrated the efficacy and safety of tenofovir disoproxil fumarate (TDF) in chronic hepatitis B (CHB). However, long-term efficacy and safety data for TDF in real-life clinical practice are limited. METHODS: Prospective German field practice study in CHB-mono-infected patients. Patients were TDF-naïve but could have been treated previously with other HBV antivirals. RESULTS: Efficacy analysis included 400 patients; 301 (75 %) completed 36 months of TDF treatment. Both treatment-naïve and treatment-experienced patients showed a rapid decline in HBV DNA within 3 months of TDF initiation. After 36 months, HBV DNA < 69 IU/mL was achieved by 91 % of treatment-naïve patients (90 and 92 % in hepatitis B "e" antigen [HBeAg]-positive and [HBeAg]-negative, respectively) and 96 % of treatment-experienced patients (93 and 97 %, respectively). Three patients experienced virologic breakthrough, all with reported non-compliance. Overall, 5.7 % HBeAg-positive and 2.2 % HBeAg-negative patients lost hepatitis B surface antigen. Safety data were consistent with the known TDF safety profile; the most commonly reported adverse events possibly related to TDF were fatigue (2.0 %) and headache (2.0 %). Few patients (1.3 %) experienced renal-related adverse reactions. Creatinine clearance remained relatively stable over time; patients responded favorably where TDF was dose adjusted per label for decreased creatinine clearance. CONCLUSIONS: TDF showed a favorable tolerability profile and induced rapid and sustained suppression of HBV DNA in patients with CHB treated for up to 3 years in routine clinical practice, irrespective of treatment history. Efficacy and safety in this heterogeneous patient population were consistent with data from clinical trials.

Hepatitis C therapy with grazoprevir/elbasvir and glecaprevir/pibrentasvir in patients with advanced chronic kidney disease: data from the German Hepatitis C-Registry (DHC-R).

OBJECTIVES: Grazoprevir/elbasvir and glecaprevir/pibrentasvir (G/P) are the two preferred treatment options for patients with chronic hepatitis C virus (HCV) infection and a glomerular filtration rate (GFR) <30 mL/min. Both therapies have been separately analyzed in different real-life cohorts; however, a direct comparison has not been performed so far. We, therefore, analyzed safety and effectiveness of both regimens in a concerted real-life population. METHODS: The Germany Hepatitis C-Registry is a prospective national real-world registry. The analysis is based on 2773 patients with documented GFR at baseline treated with grazoprevir/elbasvir (N = 1041), grazoprevir/elbasvir + ribavirin (N = 53) and glecaprevir/pibrentasvir (N = 1679). RESULTS: A total of 93 patients with GFR <30 mL/min were treated with grazoprevir/elbasvir (N = 56), grazoprevir/elbasvir + ribavirin (N = 4), and glecaprevir/pibrentasvir (N = 33). They suffered significantly more frequent from diabetes mellitus, hypertension, and coronary heart disease than individuals with GFR >30 mL/min and showed the following baseline characteristics: 20.4, 55.9, 3.2, 12.9, and 5.3% were infected with HCV-genotypes 1a, 1b, 2, 3, and 4; 12.9% suffered from liver cirrhosis; 80.1% were treatment-naïve. Baseline characteristics except distribution of HCV-genotype 1b (n = 43/52 treated with grazoprevir/elbasvir) and sustained virologic response rates (SVR12) did not differ significantly between glecaprevir/pibrentasvir (SVR12: 100%) and grazoprevir/elbasvir (SVR12: 97.9%).Fatigue, headache, abdominal discomfort, and arthralgia were the most frequently reported adverse events without a statistical difference between grazoprevir/elbasvir and glecaprevir/pibrentasvir. CONCLUSION: In patients with chronic hepatitis C and a baseline GFR ≤30 mL/min grazoprevir/elbasvir and glecaprevir/pibrentasvir show an equally favorable safety profile and antiviral efficacy and can both be recommended for real-life use.

Utilization and effectiveness of elbasvir/grazoprevir and adoption of resistance-associated substitutions testing in real-world treatment of hepatitis C virus genotype 1A infection: results from the German Hepatitis C-Registry.

BACKGROUND: For treatment of genotype 1a (GT1a) infection with elbasvir/grazoprevir, the German guidelines recommend a differentiated approach depending on baseline viral load (BVL). For low BVL ≤800 000 IU/mL, treatment with 12 weeks elbasvir/grazoprevir should be considered, whereas for high BVL >800 000 IU/mL, this regimen is only recommended in nonstructural protein 5A (NS5A) resistance-associated substitutions (RAS) absence. With present NS5A RAS or when RAS-testing is not available, 16 weeks elbasvir/grazoprevir + ribavirin is preferred. Here, we investigated the adherence to these recommendations and the effectiveness of elbasvir/grazoprevir in a large German Hepatitis C-Registry GT1a cohort. METHODS: From September 2016 until July 2018, 195 GT1a-infected patients were treated with elbasvir/grazoprevir ± ribavirin for 12-16 weeks. The primary outcome was per protocol SVR12 or SVR24. RESULTS: Mean age was 50 years, 89% were male, 19% had cirrhosis, 72% were treatment-naïve. Forty-five percent had low BVL ≤800 000 IU/mL, 55% high BVL >800 000 IU/mL, of whom 49 vs. 42% were baseline RAS-tested. Four patients with high (7.7%) and two with low BVL (5%) had NS5A RAS of whom 50% received elbasvir/grazoprevir+ribavirin, respectively. Ninety-four percent of patients with low and 65% with high BVL received elbasvir/grazoprevir without ribavirin. Thirty-five percent of patients with high BVL received ribavirin, mostly without prior RAS-testing. Per protocol sustained virologic response (SVR) by low vs. high BVL was 98.8 and 95.1%. All patients with NS5A RAS achieved SVR. CONCLUSIONS: In German, real-world most patients received elbasvir/grazoprevir without ribavirin. Ribavirin was mainly added in GT1a patients >800 000 IU/mL, who were not NS5A RAS tested. SVR rates were consistently high and comparable to clinical trial results.

Effectiveness of a community-based low intensity exercise programme for ambulatory stroke survivors.

PURPOSE: To establish the feasibility and effectiveness of a community-based exercise programme for ambulatory patients with stroke discharged from rehabilitation. METHOD: Eighteen participants were recruited 3-12 months after onset of first stroke. Using a time series experimental design, the group completed a baseline period of 4 weeks (A1), a group exercise programme of low-intensity progressive resistive exercise and functional tasks for lower limb muscles (B) and repeat assessment after cessation of exercise (A2). Fitness instructors delivered sessions at Leisure Centres twice weekly for 14 weeks with physiotherapy support and the minimum attendance requirement was 16 sessions. Measures included muscle strength, gait velocity, Berg Balance Scale and Nottingham Extended Activities of Daily Living. RESULTS: Lower limb muscle strength improved after training (ANOVA, p < 0.02). Paretic knee extension strength increased from 43.4 + or - 5.9 to 60.4 + or - 6.8 Nm after 16 exercise sessions. Walking velocity increased significantly (ANOVA, p < 0.001), from 0.54 + or - 0.07 to 0.75 + or - 0.08 m/s (t = -3.31, p < 0.01). Balance and everyday function were also significantly improved (p < 0.003). There were marked individual variation in the response to training, and those who completed additional training did not show benefit. CONCLUSIONS: This community-based exercise programme was feasible and delivered positive improvements in physical function for participants. Further issues raised for investigation include the individual response to training and the benefits of extended training.

Real-world effectiveness and safety of glecaprevir/pibrentasvir for the treatment of chronic hepatitis C infection: data from the German Hepatitis C-Registry.

BACKGROUND: Glecaprevir/pibrentasvir is a pangenotypic direct-acting antiviral regimen approved for treating adults chronically infected with hepatitis C virus (HCV). There are limited real-world data on glecaprevir/pibrentasvir to date. AIM: To evaluate the effectiveness and safety of glecaprevir/pibrentasvir under real-world conditions in the German Hepatitis C-Registry (DHC-R). METHODS: The DHC-R is an ongoing, non-interventional, multicentre, prospective, observational cohort study that monitors patients with chronic HCV infection. Data were collected from patients who initiated glecaprevir/pibrentasvir and completed a screening visit on or after 2 August 2017. The primary effectiveness endpoint was sustained virological response at post-treatment Week 12 (SVR12). Safety and tolerability were also assessed. RESULTS: As of 15 July 2018, 586 patients received glecaprevir/pibrentasvir and had documented SVR12 data, treatment discontinuation, loss to follow-up or HCV reinfection. Five hundred and fifty-two patients (94%) received on-label treatment. At baseline, most on-label patients were infected with HCV genotype 1 (53%) or 3 (33%), HCV treatment-naïve (90%), without cirrhosis (94%), and treated for 8 weeks (93%). Five hundred and thirty-four patients (96.7%) achieved SVR12 (intention-to-treat [ITT] analysis). By modified ITT analysis (excluding patients who discontinued and did not achieve SVR12 or patients lost to follow-up), the SVR12 rate was 99.4% (n/N = 534/537). There was one documented virological failure (relapse) and two documented HCV reinfections. One hundred and forty-two (26%) adverse events (AEs) and 9 (2%) serious AEs occurred; 2 (<1%) AEs led to treatment discontinuation. All patients treated off-label (N = 34) achieved SVR12. CONCLUSION: Glecaprevir/pibrentasvir was highly effective and well tolerated under real-world conditions. Clinical trial number: DRKS00009717 (German Clinical Trials Register, DRKS).

Determinants of the assembly and function of antibody variable domains.

The antibody Fv module which binds antigen consists of the variable domains VL and VH. These exhibit a conserved ß-sheet structure and comprise highly variable loops (CDRs). Little is known about the contributions of the framework residues and CDRs to their association. We exchanged conserved interface residues as well as CDR loops and tested the effects on two Fvs interacting with moderate affinities (KDs of ~2.5 µM and ~6 µM). While for the rather instable domains, almost all mutations had a negative effect, the more stable domains tolerated a number of mutations of conserved interface residues. Of particular importance for Fv association are VLP44 and VHL45. In general, the exchange of conserved residues in the VL/VH interface did not have uniform effects on domain stability. Furthermore, the effects on association and antigen binding do not strictly correlate. In addition to the interface, the CDRs modulate the variable domain framework to a significant extent as shown by swap experiments. Our study reveals a complex interplay of domain stability, association and antigen binding including an unexpected strong mutual influence of the domain framework and the CDRs on stability/association on the one side and antigen binding on the other side.

Allosteric Regulation Points Control the Conformational Dynamics of the Molecular Chaperone Hsp90.

Heat shock protein 90 (Hsp90) is an ATP-dependent molecular chaperone responsible for the activation, maturation, and trafficking of several hundred client proteins in the cell. It is well known that (but not understood how) residues far away from Hsp90's nucleotide binding pocket can regulate its ATPase activity, a phenomenon called allosteric regulation. Here, the computational design of allosteric mutations was combined with in vitro and in vivo experiments to unravel nucleotide-responsive hot spots in the regulation of Hsp90. With this approach, we identified both activating and inhibiting regulation points and show that changes in those amino acids affect the conformational dynamics and ATPase activity of Hsp90 in vitro. Our observations that activating mutations loosen and inhibiting mutations rigidify the protein explain for the first time how Hsp90 changes in response to allosteric mutations. Additionally, mutations of these allosteric regulation points can be controlled by the interplay with Hsp90 co-chaperones, thus providing cells with an efficient mechanism of modifying Hsp90's intrinsic properties via different layers of regulation. Altogether, our results show that a framework for transmitting conformational information exists in the Hsp90 structure.

Cross-Linking GPVI-Fc by Anti-Fc Antibodies Potentiates Its Inhibition of Atherosclerotic Plaque- and Collagen-Induced Platelet Activation.

To enhance the antithrombotic properties of recombinant glycoprotein VI fragment crystallizable (GPVI-Fc), the authors incubated GPVI-Fc with anti-human Fc antibodies to cross-link the Fc tails of GPVI-Fc. Cross-linking potentiated the inhibition of human plaque- and collagen-induced platelet aggregation by GPVI-Fc under static and flow conditions without increasing bleeding time in vitro. Cross-linking with anti-human-Fc Fab2 was even superior to anti-human-Fc immunoglobulin G (IgG). Advanced optical imaging revealed a continuous sheath-like coverage of collagen fibers by cross-linked GPVI-Fc complexes. Cross-linking of GPVI into oligomeric complexes provides a new, highly effective, and probably safe antithrombotic treatment as it suppresses platelet GPVI-plaque interaction selectively at the site of acute atherothrombosis.

Outcomes and Costs of Treating Hepatitis C Patients in the Era of First Generation Protease Inhibitors - Results from the PAN Study.

1 OBJECTIVE: Chronic hepatitis C virus infections (HCV) cause a significant public health burden. Introduction of telaprevir (TVR) and boceprevir (BOC) has increased sustained virologic response rates (SVR) in genotype 1 patients but were accompanied by higher treatment costs and more side effects. Aim of the study was to assess outcomes and costs of treating HCV with TVR or BOC in routine care. 2 MATERIAL AND METHODS: Data was obtained from a non-interventional study. This analysis relates on a subset of 1,786 patients for whom resource utilisation was documented. Sociodemografic and clinical parameters as well as resource utilisation were collected using a web-based data recording system. Costs were calculated using official remuneration schemes. 3 RESULTS: Mean age of patients was 49.2 years, 58.6% were male. In treatment-naive patients SVR-rates of 62.2% and 55.7% for TVR and BOC were observed (prior relapser: 68.5% for TVR and 63.5% for BOC; prior non-responder: 45.6% for TVR and 39.1% for BOC). Treatment costs are dominated by costs for pharmaceuticals and range between €39,081 and €53,491. We calculated average costs per SVR of €81,347 (TVR) and €70,163 (BOC) in treatment-naive patients (prior relapser: 78,089 €/SVR for TVR and 82,077 €/SVR for BOC; prior non-responder: 116,509 €/SVR for TVR and 110,156 €/SVR for BOC). Quality of life data showed a considerable decrease during treatment. 4 CONCLUSION: Our study is one of few investigating both, outcomes and costs, of treating HCV in a real-life setting. Data can serve as a reference in the discussion of increasing costs in recently introduced agents.

The Antibody Light-Chain Linker Is Important for Domain Stability and Amyloid Formation.

The association of light chains (LCs) and heavy chains is the basis for functional antibodies that are essential for adaptive immune responses. However, in some cases, LCs and especially fragments consisting of the LC variable (VL) domain are pathologically deposited in fatal aggregation diseases. The two domains of the LC are connected by a highly conserved linker. We show here that, unexpectedly, the linker residue Arg108 affects the conformational stability and folding of both VLκ and LC constant (CLκ) domains. Interestingly, the extension of VL by Arg108 results in its resistance to amyloid formation, which suggests that the nature of the truncation of the LC plays a crucial role in disease progression. Increased solvation due to the exposed charged C-terminal Arg108 residue explains its stabilizing effects on the VL domain. For the CL domain, the interaction of N-terminal loop residues with Arg108 is important for the integrity of the domain, as the disruption of this interaction results in fluctuation, partial opening of the protein's interior and the exposure of hydrophobic residues that destabilize the domain. This establishes new principles for antibody domain architecture and amyloidogenicity.

Performance and Value of IFN-Lambda3 and IFN-Lambda4 Genotyping in Patients with Chronic Hepatitis C (CHC) Genotype 2/3 in a Real World Setting.

BACKGROUND: SNPs near the interferon lambda (IFNL) 3 gene are predictors for sustained virological response (SVR) in patients with chronic hepatitis C genotype (GT) 1. In addition, a dinucleotide frame shift in ss469415590 was described, which generates IFNL4. In this study, we compared the role of IFNL4 variants with IFNL3-(rs12979860) and IFNL3-(rs8099917) on response to pegylated (PEG)-IFN and Ribavirin (RBV) in patients with chronic hepatitis C GT2/3. METHODS: We recruited 1006 patients with chronic hepatitis C and GT2/3 in a large German registry. A treatment with PEG-IFN and Ribavirin was started by 959 patients. We performed genotyping of IFNL3 (rs12979860, n = 726; rs8099917, n = 687) and of IFNL4 (ss469415590; n = 631). RESULTS: Both preferable IFNL3 genotypes were associated with RVR (both p<0.0001) rather than with SVR (rs12979860: p = 0.251; rs8099917: p = 0.447). Only RVR was linked to SVR in univariate and multivariate analyzes (both p<0.001). Concordance of genotyping in patients with available serum samples and EDTA blood samples (n = 259) was more than 96% for both IFNL3 SNPs. IFNL3-(rs12979860) correlated with IFNL4: 99.2% of patients with IFNL3-(rs12979860)-CC were IFNL4-(ss469415590)-TT/TT. IFNL3-(rs12979860)-CT was linked with IFNL4-(ss469415590)-TT/ΔG (98.0%) and IFNL3-(rs12979860)-TT was associated with IFNL4-(ss469415590)-ΔG/ΔG (97.6%). CONCLUSION: IFNL3 genotyping from serum was highly efficient and can be used as an alternative if EDTA whole blood is not available. In Caucasian GT2/3 patients genotyping for INFL4-(ss469415590) does not lead to additional information for the decision-making process. Importantly, IFNL3 SNPs were not associated with SVR but with RVR. Even in the era of new direct acting antiviral (DAA) therapies, IFNL3 testing may therefore still be considered for naïve GT2/3 patients to decide if dual Peg-IFN/RBV therapy is an option in resource limited regions.

Noncompliance with guidelines for the treatment of hepatitis C is frequent in daily practice.

PURPOSE: In trials of pegylated interferons (PEG-IFNs), the lack of an early virological response (EVR) was associated with sustained virological response (SVR) rates of only 0-3%. The rates were similarly low when hepatitis C virus (HCV)-RNA was positive at week 24. Treatment guidelines therefore recommend 'stop rules' on the basis of HCV-RNA levels at weeks 12 and 24 of treatment. We analyzed the use of these rules under 'real-life' conditions. PATIENTS AND METHODS: This was a prospective, community-based cohort study involving 467 physicians from institutions throughout Germany, including 4727 treatment-naive genotype-1 patients who received a full course of treatment with PEG-IFN α-2a plus ribavirin between 2003 and 2009. RESULTS: The overall SVR rate was 43.1%. Failure to determine EVR decreased from 20% in 2003-2004 to 10% in 2006-2007. Unexpectedly, treatment was continued in 86.1% of patients without an EVR and in those who had an EVR but were HCV-RNA positive at week 24 (67.5%), resulting in SVR rates of 15.7 and 40.9%, respectively. Between 77.5 and 95.3% of physicians did not follow prescribed recommendations to reduce PEG-IFN or ribavirin in cases of hematological abnormalities. CONCLUSION: Although recommendations to assess EVR and HCV-RNA at week 24 were increasingly observed in daily practice, the corresponding 'stop rules' in nonresponders were neglected. The subsequent SVR was 5-10 times higher than that reported in controlled trials. This may partly be because of the fact that reductions in PEG-IFN or ribavirin dose were not performed despite recommendations. The issue of stop rules will gain even more interest since the first HCV protease inhibitors have been approved. Prolongation of treatment beyond the new stop rules is associated with risks of resistant HCV variants. Thus, the new stop rules are to be observed more strictly when compared with previous therapy with interferons and ribavirin.

Chronic exposure to methylphenidate impairs appendicular bone quality in young rats.

Methylphenidate (MP) is a psychostimulant widely prescribed to treat Attention Deficit Hyperactivity Disorder (ADHD). Although generally well tolerated, growth deficits have been reported in children and adolescents undergoing MP treatment. This study was designed to elucidate the skeletal effects of chronic MP administration in adolescent rats. Male, 4-week-old rats received one of two doses of MP (MP-Low or MP-High) delivered for 8 h a day via drinking water, or were untreated (water only). After 13 weeks, half were sacrificed (N=12/group) and the remaining rats were left to recover, untreated for 5 additional weeks. Femora, tibiae, and L5 vertebra were analyzed using calipers, DXA, and mechanical testing. Immediately following treatment, MP decreased femoral anterior-posterior diameter (5% and 9% for MP-Low and MP-High, respectively), femoral and tibial bone mineral density (BMD) (6% and 5% for MP-High femora and tibiae, respectively), and bone mineral content (BMC) (9% for MP-High femora and tibiae). In addition, femora from MP treated rats had reduced ultimate force (20% for MP-High) and energy to failure (20% and 33% for MP-Low and MP-High, respectively). However, after recovery, there were no statistically significant differences for any measured parameters. Despite these effects on the appendicular skeleton, no differences were identified between vertebral samples at either time-point. In summary, MP treatment resulted in smaller, less mineralized, and weaker bones at appendicular sites, but did not affect the axial site. Although these effects were ameliorated within 5 weeks, these data suggest that adolescents undergoing MP treatment may be at an increased risk for long bone fractures.