First-in-class MKK4 inhibitors enhance liver regeneration and prevent liver failure

Diminished hepatocyte regeneration is a key feature of acute and chronic liver diseases and after extended liver resections, resulting in the inability to maintain or restore a sufficient functional liver mass. Therapies to restore hepatocyte regeneration are lacking, making liver transplantation the only curative option for end-stage liver disease. Here, we report on the structure-based development and characterization (nuclear magnetic resonance [NMR] spectroscopy) of first-in-class small molecule inhibitors of the dual-specificity kinase MKK4 (MKK4i). MKK4i increased liver regeneration upon hepatectomy in murine and porcine models, allowed for survival of pigs in a lethal 85% hepatectomy model, and showed antisteatotic and antifibrotic effects in liver disease mouse models. A first-in-human phase I trial (European Union Drug Regulating Authorities Clinical Trials [EudraCT] 2021-000193-28) with the clinical candidate HRX215 was conducted and revealed excellent safety and pharmacokinetics. Clinical trials to probe HRX215 for prevention/treatment of liver failure after extensive oncological liver resections or after transplantation of small grafts are warranted.

Circulating Biomarkers Instead of Genotyping to Establish Metabolizer Phenotypes

Pharmacogenomics (PGx) enables personalized treatment for the prediction of drug response and to avoid adverse drug reactions. Currently, PGx mainly relies on the genetic information of absorption, distribution, metabolism, and excretion (ADME) targets such as drug-metabolizing enzymes or transporters to predict differences in the patient's phenotype. However, there is evidence that the phenotype-genotype concordance is limited. Thus, we discuss different phenotyping strategies using exogenous xenobiotics (e.g., drug cocktails) or endogenous compounds for phenotype prediction. In particular, minimally invasive approaches focusing on liquid biopsies offer great potential to preemptively determine metabolic and transport capacities. Early studies indicate that ADME phenotyping using exosomes released from the liver is reliable. In addition, pharmacometric modeling and artificial intelligence improve phenotype prediction. However, further prospective studies are needed to demonstrate the clinical utility of individualized treatment based on phenotyping strategies, not only relying on genetics. The present review summarizes current knowledge and limitations.

Novel drug transporter substrates identification: An innovative approach based on metabolomic profiling, in silico ligand screening and biological validation

Solute carrier (SLC) transport proteins are fundamental for the translocation of endogenous compounds and drugs across membranes, thus playing a critical role in disease susceptibility and drug response. Because only a limited number of transporter substrates are currently known, the function of a large number of SLC transporters is elusive. Here, we describe the proof-of-concept of a novel strategy to identify SLC transporter substrates exemplarily for the proton-coupled peptide transporter (PEPT) 2 (SLC15A2) and multidrug and toxin extrusion (MATE) 1 transporter (SLC47A1), which are important renal transporters of drug reabsorption and excretion, respectively. By combining metabolomic profiling of mice with genetically-disrupted transporters, in silico ligand screening and in vitro transport studies for experimental validation, we identified nucleobases and nucleoside-derived anticancer and antiviral agents (flucytosine, cytarabine, gemcitabine, capecitabine) as novel drug substrates of the MATE1 transporter. Our data confirms the successful applicability of this new approach for the identification of transporter substrates in general, which may prove particularly relevant in drug research.

Performance comparison of narrow-bore and capillary liquid-chromatography for non-targeted metabolomics profiling by HILIC-QTOF-MS

Clinical metabolomics studies often have to cope with limited sample amounts, thus miniaturized liquid chromatography (LC) systems are a promising alternative. Their applicability has already been demonstrated in various fields, including a few metabolomics studies that mainly used reversed-phase chromatography. However, hydrophilic interaction chromatography (HILIC), which is widely used in metabolomics due to its particular suitability for the analysis of polar molecules, has rarely been tested for miniaturized LC-MS analysis of small molecules. In the present work, the suitability of a capillary HILIC (CapHILIC)-QTOF-MS system for non-targeted metabolomics was evaluated based on extracts of porcine formalin-fixed, paraffin-embedded (FFPE) tissue samples. The performance was assessed with respect to the number and retention time span of metabolic features as well as the analytical repeatability, the signal-to-noise ratio and the signal intensity of 16 annotated metabolites from different compound classes. The results were compared with a well established narrow-bore HILIC-QTOF-MS system. Both platforms have detected a similar number of features and performed excellent with respect to retention time stability (median RT span <0.05 min) and analytical repeatability (>75% of features with CV < 20%). The signal areas of all metabolites assessed were increased up to 18-fold by the use of CapHILIC, although the signal-to-noise ratio was only improved for 50% of the metabolites. An even better reproducibility (median CV = 5.2%) and up to 80-fold increase in signal intensity were observed after optimization of CapHILIC conditions for analysis of bile acid standard solutions. Even though the observed improvement for specific bile acids (e.g. taurocholic acid) in biological matrix needs to be evaluated, the platform comparison indicates, that the tested CapHILIC system is particularly suitable for analyses of a less broad metabolite spectrum, and specifically optimized chromatography.

Evaluation of the drug-drug interaction potential of the novel hepatitis B and D virus entry inhibitor bulevirtide at OATP1B in healthy volunteers

Introduction: Bulevirtide is a first-in-class antiviral drug to treat chronic hepatitis B/D. We investigated the drug-drug interaction potential and pharmacokinetics of high-dose subcutaneous bulevirtide (5 mg twice daily) with organic anion transporting polypeptide 1B1 (OATP1B1) and cytochrome P450 (CYP) 3A4. Methods: This was a single-center, open-label, fixed-sequence drug-drug interaction trial in 19 healthy volunteers. Before and at bulevirtide steady state, participants ingested a single 40 mg dose of pravastatin. A midazolam microdose was applied to quantify CYP3A4 activity. Results: At bulevirtide steady state, pravastatin area under the concentration-time curve (AUC_0-∞) increased 1.32-fold (90% CI 1.08-1.61). The 5 mg bulevirtide twice-daily treatment resulted in a mean AUC_0-12 of 1210 h*ng/ml (95% CI 1040-1408) and remained essentially unchanged under the influence of pravastatin. CYP3A4 activity did not change to a clinically relevant extent. As expected, total bile acids increased substantially (35-fold) compared to baseline during bulevirtide treatment. All study medication was well tolerated. Discussion: The study demonstrated that high-dose bulevirtide inhibited OATP1B-mediated hepatic uptake of the marker substrate pravastatin but the extent is considered clinically not relevant. Changes in CYP3A4 activity were also not clinically relevant. In conclusion, this study suggests that OATP1B substrate drugs as well as CYP3A4 substrates may safely be used without dose adjustment in patients treated with bulevirtide. However, in patients using high statin doses and where concomitant factors potentially further increase statin exposure, caution may be required when using bulevirtide.

Safety and efficacy of bulevirtide in combination with tenofovir disoproxil fumarate in patients with hepatitis B virus and hepatitis D virus coinfection (MYR202): a multicentre, randomised, parallel-group, open-label, phase 2 trial

BACKGROUND

Bulevirtide is a first-in-class peptidic entry inhibitor for hepatitis B virus (HBV) and hepatitis D virus infection. In July, 2020, bulevirtide 2 mg received conditional marketing authorisation by the European Medical Agency for treatment of chronic hepatitis D virus infection. We investigated the antiviral activity of bulevirtide in patients chronically infected with HBV and hepatitis D virus.

METHODS

MYR202 (ClinicalTrials.gov, NCT03546621; EudraCT, 2016-000395-13) was a multicentre, parallel-group, randomised, open-label, phase 2 trial. Adults (aged 18-65 years) with chronic hepatitis D virus infection, including patients with cirrhosis and patients who had contraindications to PegIFNα treatment or for whom treatment did not work, were eligible and were enrolled from four hospitals in Germany and 12 hospitals in Russia. Patients were randomly assigned (1:1:1:1) to receive 2 mg (n=28), 5 mg (n=32), or 10 mg (n=30) subcutaneous bulevirtide once per day with tenofovir disoproxil fumarate (TDF; 245 mg once per day orally) or TDF alone (245 mg once per day orally; n=30) for 24 weeks. Randomisation was done using a digital block scheme with stratification, consisting of 480 randomisation numbers separated into 30 blocks. The primary endpoint was undetectable hepatitis D virus RNA or 2 log₁₀ IU/mL or higher decline in hepatitis D virus RNA at week 24, which was analysed in the modified intention-to-treat population, including patients who received study medication at least once after randomisation. Hepatitis D virus RNA concentrations were monitored until week 48. Safety was assessed for all patients who received at least one dose of bulevirtide or TDF.

FINDINGS

Between Feb 16, 2016, and Dec 8, 2016, 171 patients with chronic hepatitis D virus infection were screened; 51 were ineligible based on the exclusion criteria and 120 patients (59 with cirrhosis) were enrolled. At week 24, 15 (54%, 95% CI 34-73) of 28 patients achieved undetectable hepatitis D virus RNA or a 2 log₁₀ IU/mL or more decline in hepatitis D virus RNA (p<0·0001 vs TDF alone) with 2 mg bulevirtide, 16 (50%, 32-68) of 32 with 5 mg bulevirtide (p<0·0001), and 23 (77%, 58-90) of 30 with 10 mg bulevirtide (p<0·0001), versus one (4%, 0·1-18) of 28 with TDF alone. By week 48 (24 weeks after bulevirtide cessation), hepatitis D virus RNA concentrations had rebounded, with median changes from week 24 to week 48 of 1·923 log₁₀ IU/mL (IQR 0·566-2·485) with 2 mg bulevirtide, 1·732 log₁₀ (0·469-2·568) with 5 mg bulevirtide, and 2·030 log₁₀ (1·262-2·903) with 10 mg bulevirtide. There were no deaths associated with treatment. Three (9%) patients in the bulevirtide 5 mg group, two (7%) patients in the bulevirtide 10 mg group, and one (4%) patient in the TDF group had serious adverse events. Common treatment-emergent adverse events included asymptomatic bile salt increases and increases in alanine aminotransferase and aspartate aminotransferase.

INTERPRETATION

Bulevirtide induced a significant decline in hepatitis D virus RNA over 24 weeks. After cessation of bulevirtide, hepatitis D virus RNA concentrations rebounded. Longer treatment durations and combination therapies should be investigated.

FUNDING

Hepatera LLC, MYR GmbH, and the German Centre for Infection Research, TTU Hepatitis.

Untargeted stable isotope-resolved metabolomics to assess the effect of PI3Kβ inhibition on metabolic pathway activities in a PTEN null breast cancer cell line

The combination of high-resolution LC-MS untargeted metabolomics with stable isotope-resolved tracing is a promising approach for the global exploration of metabolic pathway activities. In our established workflow we combine targeted isotopologue feature extraction with the non-targeted X¹³CMS routine. Metabolites, detected by X¹³CMS as differentially labeled between two biological conditions are subsequently integrated into the original targeted library. This strategy enables monitoring of changes in known pathways as well as the discovery of hitherto unknown metabolic alterations. Here, we demonstrate this workflow in a PTEN (phosphatase and tensin homolog) null breast cancer cell line (MDA-MB-468) exploring metabolic pathway activities in the absence and presence of the selective PI3Kβ inhibitor AZD8186. Cells were fed with [U-¹³C] glucose and treated for 1, 3, 6, and 24 h with 0.5 µM AZD8186 or vehicle, extracted by an optimized sample preparation protocol and analyzed by LC-QTOF-MS. Untargeted differential tracing of labels revealed 286 isotope-enriched features that were significantly altered between control and treatment conditions, of which 19 features could be attributed to known compounds from targeted pathways. Other 11 features were unambiguously identified based on data-dependent MS/MS spectra and reference substances. Notably, only a minority of the significantly altered features (11 and 16, respectively) were identified when preprocessing of the same data set (treatment vs. control in 24 h unlabeled samples) was performed with tools commonly used for label-free (i.e. w/o isotopic tracer) non-targeted metabolomics experiments (Profinder´s batch recursive feature extraction and XCMS). The structurally identified metabolites were integrated into the existing targeted isotopologue feature extraction workflow to enable natural abundance correction, evaluation of assay performance and assessment of drug-induced changes in pathway activities. Label incorporation was highly reproducible for the majority of isotopologues in technical replicates with a RSD below 10%. Furthermore, inter-day repeatability of a second label experiment showed strong correlation (Pearson R² > 0.99) between tracer incorporation on different days. Finally, we could identify prominent pathway activity alterations upon PI3Kβ inhibition. Besides pathways in central metabolism, known to be changed our workflow revealed additional pathways, like pyrimidine metabolism or hexosamine pathway. All pathways identified represent key metabolic processes associated with cancer metabolism and therapy.

Molybdenum Cofactor Catabolism Unravels the Physiological Role of the Drug Metabolizing Enzyme Thiopurine S-Methyltransferase

Therapy of molybdenum cofactor (Moco) deficiency has received US Food and Drug Administration (FDA) approval in 2021. Whereas urothione, the urinary excreted catabolite of Moco, is used as diagnostic biomarker for Moco-deficiency, its catabolic pathway remains unknown. Here, we identified the urothione-synthesizing methyltransferase using mouse liver tissue by anion exchange/size exclusion chromatography and peptide mass fingerprinting. We show that the catabolic Moco S-methylating enzyme corresponds to thiopurine S-methyltransferase (TPMT), a highly polymorphic drug-metabolizing enzyme associated with drug-related hematotoxicity but unknown physiological role. Urothione synthesis was investigated in vitro using recombinantly expressed human TPMT protein, liver lysates from Tpmt wild-type and knock-out (Tpmt-/- ) mice as well as human liver cytosol. Urothione levels were quantified by liquid-chromatography tandem mass spectrometry in the kidneys and urine of mice. TPMT-genotype/phenotype and excretion levels of urothione were investigated in human samples and validated in an independent population-based study. As Moco provides a physiological substrate (thiopterin) of TPMT, thiopterin-methylating activity was associated with TPMT activity determined with its drug substrate (6-thioguanin) in mice and humans. Urothione concentration was extremely low in the kidneys and urine of Tpmt-/- mice. Urinary urothione concentration in TPMT-deficient patients depends on common TPMT polymorphisms, with extremely low levels in homozygous variant carriers (TPMT*3A/*3A) but normal levels in compound heterozygous carriers (TPMT*3A/*3C) as validated in the population-based study. Our work newly identified an endogenous substrate for TPMT and shows an unprecedented link between Moco catabolism and drug metabolism. Moreover, the TPMT example indicates that phenotypic consequences of genetic polymorphisms may differ between drug- and endogenous substrates.

Hepatic Expression of the Na+-Taurocholate Cotransporting Polypeptide Is Independent from Genetic Variation

The hepatic Na+-taurocholate cotransporting polypeptide NTCP/SLC10A1 is important for the uptake of bile salts and selected drugs. Its inhibition results in increased systemic bile salt concentrations. NTCP is also the entry receptor for the hepatitis B/D virus. We investigated interindividual hepatic SLC10A1/NTCP expression using various omics technologies. SLC10A1/NTCP mRNA expression/protein abundance was quantified in well-characterized 143 human livers by real-time PCR and LC-MS/MS-based targeted proteomics. Genome-wide SNP arrays and SLC10A1 next-generation sequencing were used for genomic analyses. SLC10A1 DNA methylation was assessed through MALDI-TOF MS. Transcriptomics and untargeted metabolomics (UHPLC-Q-TOF-MS) were correlated to identify NTCP-related metabolic pathways. SLC10A1 mRNA and NTCP protein levels varied 44-fold and 10.4-fold, respectively. Non-genetic factors (e.g., smoking, alcohol consumption) influenced significantly NTCP expression. Genetic variants in SLC10A1 or other genes do not explain expression variability which was validated in livers (n = 50) from The Cancer Genome Atlas. The identified two missense SLC10A1 variants did not impair transport function in transfectants. Specific CpG sites in SLC10A1 as well as single metabolic alterations and pathways (e.g., peroxisomal and bile acid synthesis) were significantly associated with expression. Inter-individual variability of NTCP expression is multifactorial with the contribution of clinical factors, DNA methylation, transcriptional regulation as well as hepatic metabolism, but not genetic variation.

Nicotinamide-N-methyltransferase is a promising metabolic drug target for primary and metastatic clear cell renal cell carcinoma

Background

The metabolic enzyme nicotinamide‐N‐methyltransferase (NNMT) is highly expressed in various cancer entities, suggesting tumour‐promoting functions. We systematically investigated NNMT expression and its metabolic interactions in clear cell renal cell carcinoma (ccRCC), a prominent RCC subtype with metabolic alterations, to elucidate its role as a drug target.

Methods

NNMT expression was assessed in primary ccRCC (n = 134), non‐tumour tissue and ccRCC‐derived metastases (n = 145) by microarray analysis and/or immunohistochemistry. Findings were validated in The Cancer Genome Atlas (kidney renal clear cell carcinoma [KIRC], n = 452) and by single‐cell analysis. Expression was correlated with clinicopathological data and survival. Metabolic alterations in NNMT‐depleted cells were assessed by nontargeted/targeted metabolomics and extracellular flux analysis. The NNMT inhibitor (NNMTi) alone and in combination with the inhibitor 2‐deoxy‐D‐glucose for glycolysis and BPTES (bis‐2‐(5‐phenylacetamido‐1,3,4‐thiadiazol‐2‐yl)ethyl‐sulfide) for glutamine metabolism was investigated in RCC cell lines (786‐O, A498) and in two 2D ccRCC‐derived primary cultures and three 3D ccRCC air–liquid interface models.

Results

NNMT protein was overexpressed in primary ccRCC (p = 1.32 × 10^–16) and ccRCC‐derived metastases (p = 3.92 × 10^–20), irrespective of metastatic location, versus non‐tumour tissue. Single‐cell data showed predominant NNMT expression in ccRCC and not in the tumour microenvironment. High NNMT expression in primary ccRCC correlated with worse survival in independent cohorts (primary RCC—hazard ratio [HR] = 4.3, 95% confidence interval [CI]: 1.5–12.4; KIRC—HR = 3.3, 95% CI: 2.0–5.4). NNMT depletion leads to intracellular glutamine accumulation, with negative effects on mitochondrial function and cell survival, while not affecting glycolysis or glutathione metabolism. At the gene level, NNMT‐depleted cells upregulate glycolysis, oxidative phosphorylation and apoptosis pathways. NNMTi alone or in combination with 2‐deoxy‐D‐glucose and BPTES resulted in inhibition of cell viability in ccRCC cell lines and primary tumour and metastasis‐derived models. In two out of three patient‐derived ccRCC air–liquid interface models, NNMTi treatment induced cytotoxicity.

Conclusions

Since efficient glutamine utilisation, which is essential for ccRCC tumours, depends on NNMT, small‐molecule NNMT inhibitors provide a novel therapeutic strategy for ccRCC and act as sensitizers for combination therapies.

Metabolic Drug Response Phenotyping in Colorectal Cancer Organoids by LC-QTOF-MS

As metabolic rewiring is crucial for cancer cell proliferation, metabolic phenotyping of patient-derived organoids is desirable to identify drug-induced changes and trace metabolic vulnerabilities of tumor subtypes. We established a novel protocol for metabolomic and lipidomic profiling of colorectal cancer organoids by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) facing the challenge of capturing metabolic information from a minimal sample amount (<500 cells/injection) in the presence of an extracellular matrix (ECM). The best procedure of the tested protocols included ultrasonic metabolite extraction with acetonitrile/methanol/water (2:2:1, v/v/v) without ECM removal. To eliminate ECM-derived background signals, we implemented a data filtering procedure based on the p-value and fold change cut-offs, which retained features with signal intensities >120% compared to matrix-derived signals present in blank samples. As a proof-of-concept, the method was applied to examine the early metabolic response of colorectal cancer organoids to 5-fluorouracil treatment. Statistical analysis revealed dose-dependent changes in the metabolic profiles of treated organoids including elevated levels of 2′-deoxyuridine, 2′-O-methylcytidine, inosine and 1-methyladenosine and depletion of 2′-deoxyadenosine and specific phospholipids. In accordance with the mechanism of action of 5-fluorouracil, changed metabolites are mainly involved in purine and pyrimidine metabolism. The novel protocol provides a first basis for the assessment of metabolic drug response phenotypes in 3D organoid models.

Influenza vaccine effectiveness studies in Europe: SWOT analysis of DRIVE collaborating sites

Background

DRIVE is a European public-private partnership that aims at creating a network that works on high quality, brand-specific effectiveness estimates for all influenza vaccines used in the EU each season. The SWOT analysis aims at assessing the quality and feasibility of DRIVE operational model after its implementation, i.e. the operations of the study site network as applied in DRIVE.

Methods

The SWOT analysis was conducted through two meetings held among 2 of 14 partners participating in the DRIVE studies in the first season, with clinicians, nurses, data managers and lab technicians from the sites in the network. We collected data on two identified axes (1.organizational and 2.logistical, practical, and laboratory aspects), containing more than one SWOT objective. For each item classified under Strength (S), Weakness (W), Opportunity (O) or Threat (T), experts assigned a 1-5 score, meant to reflect the impact of each listed item on reaching the objectives.

Results

The most common topics, reported by both Italian and Finnish sites collaborators, were the opportunities related to the training and development of the network; funding concerns; opportunities and challenges in training the personnel; management issues due to the project practical organization (e.g. for lack of dedicated personnel, including administrative and for data entry). The scores attributed to the single items appeared skewed to the top, showing how the researchers perceived the majority of the topics as relevant for their day-to-day work.

Conclusions

The SWOT exercise was welcomed as a useful means to compare issues and practices among local study sites, but also as a chance for exchange with both peers and project lead. The results highlight the great value of communication and discussion between study groups, albeit the geographical distance. Such exercise should be included as a routine opportunity for discussion aiming at improving both collaboration and governance model in large projects.

Key messages

One of the main challenges of large public-private consortiums is building a shared governance model; opportunities for collective sharing and collaboration should be promoted in this setting. This SWOT analysis was a useful exercise that should inform the prosecution of the programming of DRIVE operational model, allowing a comparison of issues and practices among local study sites.

Integrative -omics and HLA-ligandomics analysis to identify novel drug targets for ccRCC immunotherapy

Background

Clear cell renal cell carcinoma (ccRCC) is the dominant subtype of renal cancer. With currently available therapies, cure of advanced and metastatic ccRCC is achieved only in rare cases. Here, we developed a workflow integrating different -omics technologies to identify ccRCC-specific HLA-presented peptides as potential drug targets for ccRCC immunotherapy.

Methods

We analyzed HLA-presented peptides by MS-based ligandomics of 55 ccRCC tumors (cohort 1), paired non-tumor renal tissues, and 158 benign tissues from other organs. Pathways enriched in ccRCC compared to its cell type of origin were identified by transcriptome and gene set enrichment analyses in 51 tumor tissues of the same cohort. To retrieve a list of candidate targets with involvement in ccRCC pathogenesis, ccRCC-specific pathway genes were intersected with the source genes of tumor-exclusive peptides. The candidates were validated in an independent cohort from The Cancer Genome Atlas (TCGA KIRC, n = 452). DNA methylation (TCGA KIRC, n = 273), somatic mutations (TCGA KIRC, n = 392), and gene ontology (GO) and correlations with tumor metabolites (cohort 1, n = 30) and immune-oncological markers (cohort 1, n = 37) were analyzed to characterize regulatory and functional involvements. CD8⁺ T cell priming assays were used to identify immunogenic peptides. The candidate gene EGLN3 was functionally investigated in cell culture.

Results

A total of 34,226 HLA class I- and 19,325 class II-presented peptides were identified in ccRCC tissue, of which 443 class I and 203 class II peptides were ccRCC-specific and presented in ≥ 3 tumors. One hundred eighty-five of the 499 corresponding source genes were involved in pathways activated by ccRCC tumors. After validation in the independent cohort from TCGA, 113 final candidate genes remained. Candidates were involved in extracellular matrix organization, hypoxic signaling, immune processes, and others. Nine of the 12 peptides assessed by immunogenicity analysis were able to activate naïve CD8⁺ T cells, including peptides derived from EGLN3. Functional analysis of EGLN3 revealed possible tumor-promoting functions.

Conclusions

Integration of HLA ligandomics, transcriptomics, genetic, and epigenetic data leads to the identification of novel functionally relevant therapeutic targets for ccRCC immunotherapy. Validation of the identified targets is recommended to expand the treatment landscape of ccRCC.

Simultaneous Extraction of RNA and Metabolites from Single Kidney Tissue Specimens for Combined Transcriptomic and Metabolomic Profiling

Tissue analysis represents a powerful tool for the investigation of disease pathophysiology. However, the heterogeneous nature of tissue samples, in particular of neoplastic, may affect the outcome of such analysis and hence obscure interpretation of results. Thus, comprehensive isolation and extraction of transcripts and metabolites from an identical tissue specimen would minimize variations and enable the economic use of biopsy material which is usually available in limited amounts. Here we demonstrate a fast and simple protocol for combined transcriptomics and metabolomics analysis in homogenates prepared from one single tissue sample. Metabolites were recovered by protein precipitation from lysates originally prepared for RNA isolation and were analyzed by LC-QTOF-MS after HILIC and RPLC separation, respectively. Strikingly, although ion suppression was observed, over 80% of the 2885 detected metabolic features could be extracted and analyzed with high reproducibility (CV ≤ 20%). Moreover fold changes of different tumor and nontumor kidney tissues were correlated to an established metabolomics protocol and revealed a strong correlation ( r_p ≥ 0.75). In order to demonstrate the feasibility of the combined analysis of RNA and metabolites, the protocol was applied to kidney tissue of metformin treated mice to investigate drug induced alterations.

Systemic regulation of bilirubin homeostasis: Potential benefits of hyperbilirubinemia

Neurotoxic bilirubin is the end product of heme catabolism in mammals. Bilirubin is solely conjugated by uridine diphospho-glucuronosyltransferase 1A1, which is a membrane-bound enzyme that catalyzes the transfer of glucuronic acid. Due to low function of hepatic and intestinal uridine diphospho-glucuronosyltransferase 1A1 during the neonatal period, human neonates develop mild to severe physiological hyperbilirubinemia. Accumulation of bilirubin in the brain leads to the onset of irreversible brain damage, termed kernicterus. Breastfeeding is one of the most significant factors that increase the risk of developing kernicterus in infants. Why does this most natural way of feeding increase the risk of brain damage or even death? This question leads to the hypothesis that breast milk-induced hyperbilirubinemia might bring certain benefits that outweigh those risks. While bilirubin is neurotoxic and cytotoxic, this compound is also a potent antioxidant. There are studies showing improved clinical conditions in patients with hyperbilirubinemia. Accumulating evidence also shows that genetic polymorphisms linked to hyperbilirubinemia are beneficial against various diseases. In this review article, we first introduce the production, metabolism, and transport of bilirubin. We then discuss the potential benefits of neonatal and adult hyperbilirubinemia. Finally, epigenetic factors as well as metabolomic information associated with hyperbilirubinemia are described. This review article advances the understanding of the physiological importance of the paradoxical compound bilirubin. (Hepatology 2018;67:1609-1619).

Challenges and Perspectives of Computerassisted Instruction in Medical Education

Objectives: In this paper we discuss solutions to the problem that medical teachers and students do not use modern computer-assisted instruction systems in medical education as much as expected by their developers.

Methods: As an example for a modern problem-based CAI system we introduce the CAMPUS shell system for case-based training in medicine.

Results: CAMPUS has received several awards and positive evaluation results. Nevertheless, the usage of such systems in courses and for self-study could be increased.

Conclusions: Curricular integration of CAI as well as further improvements on existing CAI systems to increase the usage in medical education is essential.

Challenges in the Evolution of the Medical Informatics Program at Heidelberg/Heilbronn (Germany)

Objective: Health and medical informatics (HMI) is an evolving discipline. Therefore, evolving educational programs in HMI have to take a variety of requirements into account. The aim of this paper is to analyze these requirements and to compare them with the medical informatics program Heidelberg/Heilbronn, Germany.

Methods: Systematic analysis of the IMIA recommendations on educating HMI, the Bologna declaration, current technological and health care developments and the results of graduates surveys.

Results: The latest revision of the Heidelberg/ Heilbronn medical informatics program not only takes current developments into account but also realizes the IMIA recommendations, the Bologna declaration and graduates’ data and feedback obtained in structured surveys. The topics bioinformatics, IT security and tele-medicine were strengthened, taking major research and application trends into account. The program has been transformed into a consecutive bachelor/master program. It qualifies its graduates to work in the field of medical informatics as well as in informatics.

Conclusions: Medical informatics is a very broad field. Programs have to make concessions to scope: It is not possible to provide profound knowledge and skills in computer science and also teach a variety of application areas like bioinformatics, public health informatics and clinical informatics in depth within one medical informatics program. Many graduate programs in various nations concentrate on providing HMI skills to health care professionals.

First-in-human application of the novel hepatitis B and hepatitis D virus entry inhibitor myrcludex B

BACKGROUND & AIMS

Myrcludex B is a first-in-class compound, which blocks entry of hepatitis B and D virus into hepatocytes in vitro and in animal models. Based on the required preclinical data we aimed to translate this compound into the first application in humans.

METHODS

Single ascending doses of myrcludex B, a 47 amino acid peptide, were administered up to 20mg intravenously and 10mg subcutaneously in a prospective open first-in-human, phase I clinical trial to 36 healthy volunteers. Safety, tolerability and plasma concentrations of myrcludex B were assessed and a pharmacokinetic model was derived.

RESULTS

Myrcludex B was well tolerated and no serious or relevant AEs representing off-target effects, and no immunogenic effects were observed up to the highest applied dose of 20mg (intravenously). Myrcludex B showed dose-dependent pharmacokinetics, best described by a 2-compartment target-mediated drug disposition model. Bioavailability of the subcutaneous application was large (85%). Interindividual variability was moderate. The pharmacokinetic model suggested that subcutaneous doses of 10mg and above reach a target saturation of over 80% for at least 15h.

CONCLUSIONS

Myrcludex B showed excellent tolerability up to high doses. Pharmacologic properties followed a 2-compartment target-mediated drug disposition model. These findings are vital for planning of further multiple dose efficacy trials in patients.

LAY SUMMARY

After showing antiviral activity in cell culture and animal models, myrcludex B, a new drug intended for the treatment of hepatitis B and D, has been administered the first time in humans. Healthy volunteers received the drug intravenously and subcutaneously up to high doses (20mg). The drug was well tolerated and the characteristics of the drug determining its way in the human body could be described. These results will allow testing myrcludex B in hepatitis B and D patients.

Treatment of chronic hepatitis D with the entry inhibitor myrcludex B: First results of a phase Ib/IIa study

BACKGROUND & AIMS

The therapeutic option for patients with chronic hepatitis delta virus infection (CHD) is limited to interferon alpha with rare curative outcome. Myrcludex B is a first-in-class entry inhibitor inactivating the hepatitis B virus (HBV) and hepatitis D virus (HDV) receptor sodium taurocholate co-transporting polypeptide. We report the interim results of a pilot trial on chronically infected HDV patients treated with myrcludex B, or pegylated interferon alpha (PegIFNα-2a) or their combination.

METHODS

Twenty-four patients with CHD infection were equally randomized (1:1:1) to receive myrcludex B, or PegIFNα-2a or their combination. Patients were evaluated for virological and biochemical response and tolerability of the study drugs at weeks 12 and 24.

RESULTS

Myrcludex B was well tolerated and no serious adverse event occurred. Although hepatitis B surface antigen levels remained unchanged, HDV RNA significantly declined at week 24 in all cohorts. HDV RNA became negative in two patients each in the Myrcludex B and PegIFNα-2a cohorts, and in five patients of the Myrcludex B+PegIFNα-2a cohort. ALT decreased significantly in the Myrcludex B cohort (six of eight patients), and HBV DNA was significantly reduced at week 24 in the Myrcludex B+PegIFNα-2a cohort. Virus kinetic modeling suggested a strong synergistic effect of myrcludex B and PegIFNα-2a on both HDV and HBV.

CONCLUSIONS

Myrcludex B showed a strong effect on HDV RNA serum levels and induced ALT normalization under monotherapy. Synergistic antiviral effects on HDV RNA and HBV DNA in the Myr-IFN cohort indicated a benefit of the combination of entry inhibition with PegIFNα-2a to treat CHD patients.

LAY SUMMARY

Myrcludex B is a new drug to treat hepatitis B and D infection. After 24weeks of treatment with myrcludex B and/or pegylated interferon α-2a, HDV R NA, a relevant marker for hepatitis D infection, decreased in all patients with chronic hepatitis B and D. Two of eight patients which received either myrcludex B or pegylated interferon α-2a, became negative for HDV RNA, and five of seven patients who received both drugs at the same time became negative. The drug was well tolerated.

Treatment of chronic hepatitis D with the entry inhibitor myrcludex B: First results of a phase Ib/IIa study

BACKGROUND & AIMS

The therapeutic option for patients with chronic hepatitis delta virus infection (CHD) is limited to interferon alpha with rare curative outcome. Myrcludex B is a first-in-class entry inhibitor inactivating the hepatitis B virus (HBV) and hepatitis D virus (HDV) receptor sodium taurocholate co-transporting polypeptide. We report the interim results of a pilot trial on chronically infected HDV patients treated with myrcludex B, or pegylated interferon alpha (PegIFNα-2a) or their combination.

METHODS

Twenty-four patients with CHD infection were equally randomized (1:1:1) to receive myrcludex B, or PegIFNα-2a or their combination. Patients were evaluated for virological and biochemical response and tolerability of the study drugs at weeks 12 and 24.

RESULTS

Myrcludex B was well tolerated and no serious adverse event occurred. Although hepatitis B surface antigen levels remained unchanged, HDV RNA significantly declined at week 24 in all cohorts. HDV RNA became negative in two patients each in the Myrcludex B and PegIFNα-2a cohorts, and in five patients of the Myrcludex B+PegIFNα-2a cohort. ALT decreased significantly in the Myrcludex B cohort (six of eight patients), and HBV DNA was significantly reduced at week 24 in the Myrcludex B+PegIFNα-2a cohort. Virus kinetic modeling suggested a strong synergistic effect of myrcludex B and PegIFNα-2a on both HDV and HBV.

CONCLUSIONS

Myrcludex B showed a strong effect on HDV RNA serum levels and induced ALT normalization under monotherapy. Synergistic antiviral effects on HDV RNA and HBV DNA in the Myr-IFN cohort indicated a benefit of the combination of entry inhibition with PegIFNα-2a to treat CHD patients.

LAY SUMMARY

Myrcludex B is a new drug to treat hepatitis B and D infection. After 24weeks of treatment with myrcludex B and/or pegylated interferon α-2a, HDV R NA, a relevant marker for hepatitis D infection, decreased in all patients with chronic hepatitis B and D. Two of eight patients which received either myrcludex B or pegylated interferon α-2a, became negative for HDV RNA, and five of seven patients who received both drugs at the same time became negative. The drug was well tolerated.

A Rare Case of Emberger Syndrome Caused By a De Novo Mutation in the GATA2 Gene

Emberger syndrome, or primary lymphedema with myelodysplasia, is a severe rare disease characterized by early primary lymphedema and blood anomalies including acute childhood leukemia. The syndrome is associated with heterozygous mutations in the GATA2 gene. We report on a 13-year-old boy who developed lymphedema of the right lower limb at age 6 years which was accompanied by severe panleukopenia and repeated episodes of erysipelas. The suspicion of Emberger syndrome was confirmed by detection of a new germinal line GATA2 mutation c.414_417del, p.Ser139Cysfs*78. Clinical treatment included a bone marrow transplant from the father.This case is one of a very limited number of Emberger syndrome cases documented in the literature, and genetic testing proved fundamental for definition of the condition and its association with a de novo mutation in the GATA2 which is reported here for the first time.

Interaction of MDM33 with mitochondrial inner membrane homeostasis pathways in yeast

Membrane homeostasis affects mitochondrial dynamics, morphology, and function. Here we report genetic and proteomic data that reveal multiple interactions of Mdm33, a protein essential for normal mitochondrial structure, with components of phospholipid metabolism and mitochondrial inner membrane homeostasis. We screened for suppressors of MDM33 overexpression-induced growth arrest and isolated binding partners by immunoprecipitation of cross-linked cell extracts. These approaches revealed genetic and proteomic interactions of Mdm33 with prohibitins, Phb1 and Phb2, which are key components of mitochondrial inner membrane homeostasis. Lipid profiling by mass spectrometry of mitochondria isolated from Mdm33-overexpressing cells revealed that high levels of Mdm33 affect the levels of phosphatidylethanolamine and cardiolipin, the two key inner membrane phospholipids. Furthermore, we show that cells lacking Mdm33 show strongly decreased mitochondrial fission activity indicating that Mdm33 is critical for mitochondrial membrane dynamics. Our data suggest that MDM33 functionally interacts with components important for inner membrane homeostasis and thereby supports mitochondrial division.

Quantitative bile acid profiling by liquid chromatography quadrupole time-of-flight mass spectrometry: monitoring hepatitis B therapy by a novel Na(+)-taurocholate cotransporting polypeptide inhibitor

A novel analytical approach for the targeted profiling of bile acids (BAs) in human serum/plasma based on liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) is presented. Reversed-phase chromatography enabled the baseline separation of 15 human BA species which could be readily detected by accurate mass analysis in negative ion mode. Blood proteins were removed by methanol precipitation in the presence of deuterium-labeled internal standards which allowed BA quantification in 50 μl plasma/serum. The assay was validated according to FDA guidance achieving quantification limits from 7.8 to 156 nM. Calibration curves prepared in charcoal-stripped serum/plasma showed excellent regression coefficients (R (2) > 0.997) and covered quantities from 7.8 to 10,000 nM depending on the analyzed species. Intra- and inter-day accuracy and precision were below 15 % for all analytes. Apparent extraction recoveries were above 97 %, and ion suppression rates were between 4 and 53 %. Mean BA level in serum/plasma from healthy volunteers ranged from 11 ± 4 nM (tauroursodeoxycholic acid) to 1321 ± 1442 nM (glycochenodeoxycholic acid). As a proof of concept, the assay was applied to plasma samples derived from a clinical phase I study of myrcludex B, a novel first-in-class virus entry inhibitor for the treatment of chronic hepatitis B and D. The results demonstrate that myrcludex-induced inhibition of the hepatic BA transporter Na(+)-taurocholate cotransporting polypeptide (NTCP) significantly affects plasma BA level. These observations provide novel insights into drug-induced metabolic responses and will be indispensable for the assessment of side effects and dose-finding processes during future clinical trials.

DNAJC19, a mitochondrial cochaperone associated with cardiomyopathy, forms a complex with prohibitins to regulate cardiolipin remodeling

Prohibitins form large protein and lipid scaffolds in the inner membrane of mitochondria that are required for mitochondrial morphogenesis, neuronal survival, and normal lifespan. Here, we have defined the interactome of PHB2 in mitochondria and identified DNAJC19, mutated in dilated cardiomyopathy with ataxia, as binding partner of PHB complexes. We observed impaired cell growth, defective cristae morphogenesis, and similar transcriptional responses in the absence of either DNAJC19 or PHB2. The loss of PHB/DNAJC19 complexes affects cardiolipin acylation and leads to the accumulation of cardiolipin species with altered acyl chains. Similar defects occur in cells lacking the transacylase tafazzin, which is mutated in Barth syndrome. Our experiments suggest that PHB/DNAJC19 membrane domains regulate cardiolipin remodeling by tafazzin and explain similar clinical symptoms in two inherited cardiomyopathies by an impaired cardiolipin metabolism in mitochondrial membranes.

[Arthroscopic nerve release and decompression of ganglion cysts around the shoulder joint]

OBJECTIVE

Arthroscopic visualisation and release of nerves around the shoulder, decompression of ganglion cysts.

INDICATIONS

Arthroscopic treatment of nerve entrapment syndromes around the shoulder (suprascapular nerve, axillary nerve). Arthroscopic visualisation and release of osseous or ligamentous structures causing nerve entrapment. Arthroscopic decompression and resection of periglenoid ganglion cysts. Arthroscopic release of concomitant lesions (labrum, rotator cuff, biceps).

CONTRAINDICATIONS

No clinical or neurological evidence for nerve entrapment syndrome. Lack of conditions for a complex arthroscopic procedure (technique of visualisation, instrumentation, knowledge of specific neuroanatomy).

SURGICAL TECHNIQUE

Diagnostic arthroscopy, decompression/resection of ganglion cyst. Visualisation and decompression of nerve. Detection and fixation of concomitant pathologies.

POSTOPERATIVE TREATMENT

Immobilisation in sling during the day after the operation. Actively assisted and active mobilisation of shoulder controlled by discomfort level. Manual lymph drainage starting on postoperative day 1. Sling and further rehabilitation according to treatment of concomitant lesions.

Possible combinations of electronic data capture and randomization systems. principles and the realization with RANDI2 and OpenClinica

BACKGROUND

Clinical trials (CT) are in a wider sense experiments to prove and establish clinical benefit of treatments. Nowadays electronic data capture systems (EDCS) are used more often bringing a better data management and higher data quality into clinical practice. Also electronic systems for the randomization are used to assign the patients to the treatments.

OBJECTIVES

If the mentioned randomization system (RS) and EDCS are used, possibly identical data are collected in both, especially by stratified randomization. This separated data storage may lead to data inconsistency and in general data samples have to be aligned. The article discusses solutions to combine RS and EDCS. In detail one approach is realized and introduced.

METHODS

Different possible settings of combination of EDCS and RS are determined and the pros and cons for each solution are worked out. For the combination of two independent applications the necessary interfaces for the communication are defined. Thereby, existing standards are considered. An example realization is implemented with the help of open-source applications and state-of-the-art software development procedures.

RESULTS

Three possibilities of separate usage or combination of EDCS and RS are presented and assessed: i) the complete independent usage of both systems; ii) realization of one system with both functions; and iii) two separate systems, which communicate via defined interfaces. In addition a realization of our preferred approach, the combination of both systems, is introduced using the open source tools RANDI2 and OpenClinica.

CONCLUSION

The advantage of a flexible independent development of EDCS and RS is shown based on the fact that these tool are very different featured. In our opinion the combination of both systems via defined interfaces fulfills the requirements of randomization and electronic data capture and is feasible in practice. In addition, the use of such a setting can reduce the training costs and the error-prone duplicated data entry.

An apparatus for pulsed ESR and DNP experiments using optically excited triplet states down to liquid helium temperatures

In standard Dynamic Nuclear Polarization (DNP) electron spins are polarized at low temperatures in a strong magnetic field and this polarization is transferred to the nuclear spins by means of a microwave field. To obtain high nuclear polarizations cryogenic equipment reaching temperatures of 1 K or below and superconducting magnets delivering several Tesla are required. This equipment strongly limits applications in nuclear and particle physics where beams of particles interact with the polarized nuclei, as well as in neutron scattering science. The problem can be solved using short-lived optically excited triplet states delivering the electron spin. The spin is polarized in the optical excitation process and both the cryogenic equipment and magnet can be simplified significantly. A versatile apparatus is described that allows to perform pulsed dynamic nuclear polarization experiments at X-band using short-lived optically excited triplet sates. The efficient (4)He flow cryostat that cools the sample to temperatures between 4 K and 300 K has an optical access with a coupling stage for a fiber transporting the light from a dedicated laser system. It is further designed to be operated on a neutron beam. A combined pulse ESR/DNP spectrometer has been developed to observe and characterize the triplet states and to perform pulse DNP experiments. The ESR probe is based on a dielectric ring resonator of 7 mm inner diameter that can accommodate cubic samples of 5mm length needed for neutron experiments. NMR measurements can be performed during DNP with a coil integrated in the cavity. With the presented apparatus a proton polarization of 0.5 has been achieved at 0.3 T.

TRIAP1/PRELI complexes prevent apoptosis by mediating intramitochondrial transport of phosphatidic acid

Cardiolipin (CL), a mitochondria-specific glycerophospholipid, is required for diverse mitochondrial processes and orchestrates the function of various death-inducing proteins during apoptosis. Here, we identify a complex of the p53-regulated protein TRIAP1 (p53CSV) and PRELI in the mitochondrial intermembrane space (IMS), which ensures the accumulation of CL in mitochondria. TRIAP1/PRELI complexes exert lipid transfer activity in vitro and supply phosphatidic acid (PA) for CL synthesis in the inner membrane. Loss of TRIAP1 or PRELI impairs the accumulation of CL, facilitates the release of cytochrome c, and renders cells vulnerable to apoptosis upon intrinsic and extrinsic stimulation. Survival of TRIAP1- and PRELI-deficient cells is conferred by an excess of exogenously provided phosphatidylglycerol. Our results reveal a p53-dependent cell-survival pathway and highlight the importance of the CL content of mitochondrial membranes in apoptosis.

Human regulatory T cells rapidly suppress T cell receptor-induced Ca(2+), NF-κB, and NFAT signaling in conventional T cells

CD4(+)CD25(hi)Foxp3(+) regulatory T cells (T(regs)) are critical mediators of self-tolerance, which is crucial for the prevention of autoimmune disease, but T(regs) can also inhibit antitumor immunity. T(regs) inhibit the proliferation of CD4(+)CD25(-) conventional T cells (T(cons)), as well as the ability of these cells to produce effector cytokines; however, the molecular mechanism of suppression remains unclear. Here, we showed that human T(regs) rapidly suppressed the release of calcium ions (Ca(2+)) from intracellular stores in response to T cell receptor (TCR) activation in T(cons). The inhibition of Ca(2+) signaling resulted in decreased dephosphorylation, and thus decreased activation, of the transcription factor nuclear factor of activated T cells 1 (NFAT1) and reduced the activation of nuclear factor κB (NF-κB). In contrast, Ca(2+)-independent events in T(cons), such as TCR-proximal signaling and activation of the transcription factor activator protein 1 (AP-1), were not affected during coculture with T(regs). Despite suppressing intracellular Ca(2+) mobilization, coculture with T(regs) did not block the generation of inositol 1,4,5-trisphosphate in TCR-stimulated T(cons). The T(reg)-induced suppression of the activity of NFAT and NF-κB and of the expression of the gene encoding the cytokine interleukin-2 was reversed in T(cons) by increasing the concentration of intracellular Ca(2+). Our results elucidate a previously unrecognized and rapid mechanism of T(reg)-mediated suppression. This increased understanding of T(reg) function may be exploited to generate possible therapies for the treatment of autoimmune diseases and cancer.

Cardiovascular and gastrointestinal safety of NSAIDs: a systematic review of meta-analyses of randomized clinical trials

As part of the Safety of Non-Steroidal Anti-Inflammatory Drugs (SOS) Project, we reviewed the incidence of cardiovascular (CV) and gastrointestinal (GI) events associated with the use of this category of drugs. We collected data from published meta-analyses (MAs) of clinical trials of nonsteroidal anti-inflammatory drugs (NSAIDs). The Medline, Cochrane, ISI, and SCOPUS databases were systematically searched for MAs of NSAID clinical trials that could potentially contain data on adverse incidents such as myocardial infarction (MI), cerebrovascular events (CeVs), stroke, thromboembolic events (ThEs), heart failure (HF), gastrointestinal bleeding (GIB), and perforation, ulcer, and bleeding (PUB). From 1,733 identified references, 29 MAs were selected for the review. This allowed 109 estimations of incidence rates of CV adverse events and 26 estimations of incidence rates for GI adverse events. No data were found on hemorrhagic stroke or LGIB. Coxibs were studied in more MAs than traditional NSAIDs were (21 MAs for coxibs vs. 7 for traditional NSAIDs; one meta-analysis studied both). Many NSAIDs were not considered in any of the MAs. Our systematic review of MAs included information on the incidence of CV and GI events and identified important knowledge gaps regarding, in particular, the CV safety of traditional NSAIDs.

Short-term fatty acid effects on adipocyte glucose uptake: mechanistic insights

The modulation of insulin sensitivity in visceral fat tissue could be important in the treatment of Type 2 diabetes mellitus. Selected fatty acids may impact on insulin-stimulated and basal glucose uptake in adipocytes, thus isolated rat epididymal adipocytes were exposed to 100 microM oleic, arachidonic, eicosapentaenoic, docosahexaenoic or stearic acids and insulin (15 nM) or vehicle for 30 min. Glucose uptake was quantified by measuring uptake of 3H-deoxyglucose/mg adipocyte protein/min. Where appropriate, inhibitors were included to elucidate the mechanisms involved. In this model, insulin stimulated glucose uptake with 62+/-7%. All fatty acids tested, except for stearic acid, depressed insulin-stimulated glucose uptake by an average of 33+/-4.2%. On the other hand, all fatty acids tested except stearic and arachidonic acids, stimulated basal glucose uptake with an average of 34+/-8.1%. Inhibitor studies showed the involvement of prostaglandins, lipoxins, protein kinase C and tyrosine kinase in these processes.

The genetic interactome of prohibitins: coordinated control of cardiolipin and phosphatidylethanolamine by conserved regulators in mitochondria

Prohibitin ring complexes in the mitochondrial inner membrane regulate cell proliferation as well as the dynamics and function of mitochondria. Although prohibitins are essential in higher eukaryotes, prohibitin-deficient yeast cells are viable and exhibit a reduced replicative life span. Here, we define the genetic interactome of prohibitins in yeast using synthetic genetic arrays, and identify 35 genetic interactors of prohibitins (GEP genes) required for cell survival in the absence of prohibitins. Proteins encoded by these genes include members of a conserved protein family, Ups1 and Gep1, which affect the processing of the dynamin-like GTPase Mgm1 and thereby modulate cristae morphogenesis. We show that Ups1 and Gep1 regulate the levels of cardiolipin and phosphatidylethanolamine in mitochondria in a lipid-specific but coordinated manner. Lipid profiling by mass spectrometry of GEP-deficient mitochondria reveals a critical role of cardiolipin and phosphatidylethanolamine for survival of prohibitin-deficient cells. We propose that prohibitins control inner membrane organization and integrity by acting as protein and lipid scaffolds.

High-repetition-rate optical parametric chirped-pulse amplifier producing 1-microJ, sub-100-fs pulses in the mid-infrared

We present a high-repetition-rate, femtosecond optical parametric chirped pulse amplifier (OPCPA). Its seed signal is obtained by difference frequency generation from the two-branch output of a commercially available Er:fiber laser amplifier. The optical parametric amplifier is pumped by a commercially available diode-pumped solid-state laser. In a two-stage amplification setup we have achieved a gain of 100'000, resulting in approximately 1 microJ femtosecond mid-infrared pulses in the wavelength range between 3 and 4 microm and an amplification bandwidth of >300 nm at a repetition rate of 100 kHz. The pulses have been compressed to 92 fs by a 4-prism compressor.

Classification of graft hypertrophy after autologous chondrocyte implantation of full-thickness chondral defects in the knee

OBJECTIVE

Graft hypertrophy is a major complication seen in autologous chondrocyte implantation (ACI) with a periosteal flap. We present the first magnetic resonance imaging (MRI) classification for periosteal hypertrophy including a grading of clinical symptoms and the surgical consequences.

METHODS

One hundred and two patients with isolated chondral defects underwent an ACI covered with periosteum and were evaluated preoperatively, 6, 18 and 36 months after surgery. Exclusion criteria were meniscal pathologies, axial malpositioning and ligament instabilities. Baseline clinical scores were compared with follow-up data by paired Wilcoxon-tests for the modified Cincinnati knee, the ICRS (International Cartilage Repair Society) and a new MRI score including the parameters defect filling, subchondral edema, effusion, cartilage signal and graft hypertrophy. Hypertrophic changes were graded from 1 (minimal) to 4 (severe).

RESULTS

All scores showed significant improvement (P<0.001) over the entire study period. Patients with femoral lesions had significantly better results than patients with patella lesions after 18 and 36 months postoperative (P<0.03). Periosteal hypertrophy occurred in 28% of all patients. Fifty percent of all patella implants developed hypertrophic changes. No patient with grade 1, and all patients with grade 4 hypertrophy had to undergo revision surgery. The Pearson correlation between graft hypertrophy and ICRS score was 0.78 after 6 months, and 0.69 after 36 months (P<0.01). Inclusion of graft hypertrophy in the MRI score improves the correlation to clinical scores from 0.6 to 0.69.

CONCLUSIONS

Grading graft hypertrophy helps to identify patients needing an early shaving of the graft. Its integration into an MRI score improves correlation with clinical scores. Re-operation depends on the grade of hypertrophy and clinical symptoms.

Effects of arachidonic acid, docosahexaenoic acid and prostaglandin E(2) on cell proliferation and morphology of MG-63 and MC3T3-E1 osteoblast-like cells

During bone remodelling bone is resorbed by osteoclasts and replaced again by osteoblasts through the process of bone formation. Clinical trials and in vivo animal studies suggest that specific polyunsaturated fatty acids (PUFAs) might benefit bone health. As the number of functional osteoblasts is important for bone formation the effects of specific PUFAs on in vitro osteoblastic cell proliferation were investigated. Morphological studies were conducted to determine whether exposure of the cells to these agents caused structural damage to the cells thereby yielding invalid results. Results from this study showed that arachidonic acid (AA) and docosahexaenoic acid (DHA) both inhibit cell growth significantly at high concentrations. The anti-mitotic effect of AA is possibly independent of PGE(2) production, as PGE(2) per se had little effect on proliferation. Further study is required to determine whether reduced proliferation due to fatty acids could be due to increased differentiation of osteoblasts to the mature mineralising osteoblastic phenotype.