Targeting ATR in patients with cancer

Pharmacological inhibition of the ataxia telangiectasia and Rad3-related protein serine/threonine kinase (ATR; also known as FRAP-related protein (FRP1)) has emerged as a promising strategy for cancer treatment that exploits synthetic lethal interactions with proteins involved in DNA damage repair, overcomes resistance to other therapies and enhances antitumour immunity. Multiple novel, potent ATR inhibitors are being tested in clinical trials using biomarker-directed approaches and involving patients across a broad range of solid cancer types; some of these inhibitors have now entered phase III trials. Further insight into the complex interactions of ATR with other DNA replication stress response pathway components and with the immune system is necessary in order to optimally harness the potential of ATR inhibitors in the clinic and achieve hypomorphic targeting of the various ATR functions. Furthermore, a deeper understanding of the diverse range of predictive biomarkers of response to ATR inhibitors and of the intraclass differences between these agents could help to refine trial design and patient selection strategies. Key challenges that remain in the clinical development of ATR inhibitors include the optimization of their therapeutic index and the development of rational combinations with these agents. In this Review, we detail the molecular mechanisms regulated by ATR and their clinical relevance, and discuss the challenges that must be addressed to extend the benefit of ATR inhibitors to a broad population of patients with cancer.

Discovery of the Potent and Selective ATR Inhibitor Camonsertib (RP-3500)

ATR is a key kinase in the DNA-damage response (DDR) that is synthetic lethal with several other DDR proteins, making it an attractive target for the treatment of genetically selected solid tumors. Herein we describe the discovery of a novel ATR inhibitor guided by a pharmacophore model to position a key hydrogen bond. Optimization was driven by potency and selectivity over the related kinase mTOR, resulting in the identification of camonsertib (RP-3500) with high potency and excellent ADME properties. Preclinical evaluation focused on the impact of camonsertib on myelosuppression, and an exploration of intermittent dosing schedules to allow recovery of the erythroid compartment and mitigate anemia. Camonsertib is currently undergoing clinical evaluation both as a single agent and in combination with talazoparib, olaparib, niraparib, lunresertib, or gemcitabine (NCT04497116, NCT04972110, NCT04855656). A preliminary recommended phase 2 dose for monotherapy was identified as 160 mg QD given 3 days/week.

Movements and spatial distribution of an endangered fish (Sciaena umbra) within a marine protected area

The brown meagre (Sciaena umbra) is an endangered species, which requires specific protection measures to ensure its conservation. These measures need to be informed by high-quality scientific knowledge on their space use patterns. Here, we used acoustic telemetry to assess its seasonal movement patterns and habitat use within a marine protected area (MPA). Our results suggested that S. umbra is a highly sedentary species (home range < 1.0 km2) and, therefore, the MPA is extensive enough to protect the local population. Their population was discretely distributed in two main areas within the MPA, which was likely a result of habitat segregation and density-dependent movements. The temporal variability of their movements further uncovered when and where spawning occurs (mainly, but probably not only, in the fully protected area in June) and indicated that spillover of this species is limited but still possible. Overall, we highlight the importance of MPAs in the recovery of S. umbra, we advocate the need to perpetuate the current national fishing bans and extend it to other countries in the Mediterranean region, and we emphasize that considering the fine-scale movements of S. umbra in future management actions is key to achieving a successful recovery of their populations.

Towards Clinical Translation of Microbeam Radiation Therapy (MRT) with a Compact Source

PURPOSE/OBJECTIVE(S)

MRT is an innovative concept of spatially fractionated radiation therapy that has demonstrated substantially improved normal tissue tolerance while achieving local tumor control in a wealth of preclinical studies. In MRT a collimator shapes a few micrometers wide planar x-ray beams with a spacing of a few 100 µm. MRT has the potential to improve cancer treatment substantially. However, until now, only a few large 3rd generation synchrotrons provide beam parameters that would allow patient treatments and therefore, MRT has not yet become clinically available. For a clinical translation, compact x-ray sources are required, that produce high dose rate orthovoltage x-rays from a micrometer sized emitter.

MATERIALS/METHODS

We developed and built a first prototype of a line focus x-ray tube (LFxT) dedicated to preclinical MRT research. By exploiting the heat capacity limit, the LFxT can deliver dose rates above 100 Gy/s from a just 50 µm-wide focal spot without destroying the rapidly (>200 Hz) rotating x-ray target. A bespoke collimator splits the homogeneous x-ray field into 50 µm wide high-dose peaks separated by 350 µm wide low-dose troughs (valleys). While the prototype in our lab is restricted to a power of 90 kW and 10 Gy/s at 300 kVp, we have started the development of the first clinically usable LFxT-2 at 1.5 MW power and >100 Gy/s at 600 kVp beam quality. We investigated the clinical applicability of the LFxT-2 by performing retrospective treatment planning studies. In particular, we were examining, whether 600 kVp photons would suffice to meet clinical dose constraints in MRT treatments treatment scenarios for first clinical use of MRT. We coupled the open source platform 3D Slicer with an in-house developed dose calculation algorithm for MRT treatment planning. For comparability of spatially fractionated MRT doses with conventional broad beam treatments, the MRT dose was converted to equivalent uniform dose (EUD) and equivalent doses in 2-Gy-fractions (EQD2). The 3D Slicer RT toolkit enabled the dosimetric analysis based on dose volume histograms (DVHs).

RESULTS

We installed a preclinical prototype of the LFxT that is currently put into operation and commissioned. Simulations show the feasibility of the next generation LFxT-2 with more than 100 Gy/s peak dose rate. Planned MRT dose distributions with the LFxT-2 meet established radiotherapy dose constraints in many of the investigated clinical cases. However, treatment planning procedures are not yet optimal and require improvement.

CONCLUSION

In a next step, we will build the LFxT-2 and aim for first clinical MRT trials at this source. In order to further improve calculated MRT dose distributions, we will implement inverse treatment planning techniques.

Validity Assessment of an Automated Brain Morphometry Tool for Patients with De Novo Memory Symptoms

BACKGROUND AND PURPOSE

Automated volumetric analysis of structural MR imaging allows quantitative assessment of brain atrophy in neurodegenerative disorders. We compared the brain segmentation performance of the AI-Rad Companion brain MR imaging software against an in-house FreeSurfer 7.1.1/Individual Longitudinal Participant pipeline.

MATERIALS AND METHODS

T1-weighted images of 45 participants with de novo memory symptoms were selected from the OASIS-4 database and analyzed through the AI-Rad Companion brain MR imaging tool and the FreeSurfer 7.1.1/Individual Longitudinal Participant pipeline. Correlation, agreement, and consistency between the 2 tools were compared among the absolute, normalized, and standardized volumes. Final reports generated by each tool were used to compare the rates of detection of abnormality and the compatibility of radiologic impressions made using each tool, compared with the clinical diagnoses.

RESULTS

We observed strong correlation, moderate consistency, and poor agreement between absolute volumes of the main cortical lobes and subcortical structures measured by the AI-Rad Companion brain MR imaging tool compared with FreeSurfer. The strength of the correlations increased after normalizing the measurements to the total intracranial volume. Standardized measurements differed significantly between the 2 tools, likely owing to differences in the normative data sets used to calibrate each tool. When considering the FreeSurfer 7.1.1/Individual Longitudinal Participant pipeline as a reference standard, the AI-Rad Companion brain MR imaging tool had a specificity of 90.6%-100% and a sensitivity of 64.3%-100% in detecting volumetric abnormalities. There was no difference between the rate of compatibility of radiologic and clinical impressions when using the 2 tools.

CONCLUSIONS

The AI-Rad Companion brain MR imaging tool reliably detects atrophy in cortical and subcortical regions implicated in the differential diagnosis of dementia.

Guiding ATR and PARP inhibitor combinationswith chemogenomic screens

Combinations of ataxia telangiectasia- and Rad3-related kinase inhibitors (ATRis) and poly(ADP-ribose) polymerase inhibitors (PARPis) synergistically kill tumor cells through modulation of complementary DNA repair pathways, but their tolerability is limited by hematological toxicities. To address this, we performed a genome-wide CRISPR-Cas9 screen to identify genetic alterations that hypersensitize cells to a combination of the ATRi RP-3500 with PARPi, including deficiency in RNase H2, RAD51 paralog mutations, or the "alternative lengthening of telomeres" telomere maintenance mechanism. We show that RP-3500 and PARPi combinations kill cells carrying these genetic alterations at doses sub-therapeutic as single agents. We also demonstrate the mechanism of combination hypersensitivity in RNase H2-deficient cells, where we observe an irreversible replication catastrophe, allowing us to design a highly efficacious and tolerable in vivo dosing schedule. We present a comprehensive dataset to inform development of ATRi and PARPi combinations and an experimental framework applicable to other drug combination strategies.

RP-3500: A Novel, Potent, and Selective ATR Inhibitor that is Effective in Preclinical Models as a Monotherapy and in Combination with PARP Inhibitors

Ataxia telangiectasia and Rad3-related (ATR) kinase protects genome integrity during DNA replication. RP-3500 is a novel, orally bioavailable clinical-stage ATR kinase inhibitor (NCT04497116). RP-3500 is highly potent with IC₅₀ values of 1.0 and 0.33 nmol/L in biochemical and cell-based assays, respectively. RP-3500 is highly selective for ATR with 30-fold selectivity over mammalian target of rapamycin (mTOR) and more than 2,000-fold selectivity over ataxia telangiectasia mutated (ATM), DNA-dependent protein kinase (DNA-PK), and phosphatidylinositol 3-kinase alpha (PI3Kα) kinases. In vivo, RP-3500 treatment results in potent single-agent efficacy and/or tumor regression in multiple xenograft models at minimum effective doses (MED) of 5 to 7 mg/kg once daily. Pharmacodynamic assessments validate target engagement, with dose-proportional tumor inhibition of phosphorylated checkpoint kinase 1 (pCHK1) (IC₈₀ = 18.6 nmol/L) and induction of phosphorylated H2A.X variant histone (γH2AX), phosphorylated DNA-PK catalytic subunit (pDNA-PKcs), and phosphorylated KRAB-associated protein 1 (pKAP1). RP-3500 exposure at MED indicates that circulating free plasma levels above the in vivo tumor IC₈₀ for 10 to 12 hours are sufficient for efficacy on a continuous schedule. However, short-duration intermittent (weekly 3 days on/4 days off) dosing schedules as monotherapy or given concomitantly with reduced doses of olaparib or niraparib, maximize tumor growth inhibition while minimizing the impact on red blood cell depletion, emphasizing the reversible nature of erythroid toxicity with RP-3500 and demonstrating superior efficacy compared with sequential treatment. These results provide a strong preclinical rationale to support ongoing clinical investigation of the novel ATR inhibitor, RP-3500, on an intermittent schedule as a monotherapy and in combination with PARP inhibitors as a potential means of maximizing clinical benefit.

ATM Germline Mutated Gastroesophageal Junction Adenocarcinomas: Clinical Descriptors, Molecular Characteristics and Potential Therapeutic Implications

Background

Gastroesophageal junction (GEJ) adenocarcinoma is a rare cancer associated with poor prognosis. The genetic factors conferring predisposition to GEJ adenocarcinoma have yet to be identified.

Methods

We analyzed germline testing results from 23 381 cancer patients undergoing tumor-normal sequencing, of which 312 individuals had GEJ adenocarcinoma. Genomic profiles and clinico-pathologic features were analyzed for the GEJ adenocarcinomas. Silencing of ATM and ATR was performed using validated short-interfering RNA species in GEJ, esophageal, and gastric adenocarcinoma cell lines. All statistical tests were 2-sided.

Results

Pathogenic or likely pathogenic ATM variants were identified in 18 of 312 patients (5.8%), and bi-allelic inactivation of ATM through loss of heterozygosity of the wild-type allele was detected in all (16 of 16) samples with sufficient tumor content. Germline ATM-mutated GEJ adenocarcinomas largely lacked somatic mutations in TP53, were more likely to harbor MDM2 amplification, and harbored statistically significantly fewer somatic single nucleotide variants (2.0 mutations/Mb vs 7.9 mutations/Mb; P < .001). A statistically significantly higher proportion of germline ATM-mutated than ATM–wild-type GEJ adenocarcinoma patients underwent a curative resection (10 [100%] vs 92 [86.8%], P = .04; Fisher’s exact test.), A synthetic lethal interaction between short-interfering RNA silencing of ATM and ATR was observed in the models analyzed.

Conclusions

Our results indicate that germline pathogenic variants in ATM drive oncogenesis in GEJ adenocarcinoma and might result in a distinct clinical phenotype. Given the high prevalence of germline ATM-mutated GEJ adenocarcinomas, genetic testing for individuals with GEJ adenocarcinomas may be considered to better inform prognostication, treatment decisions, and future cancer risk.

Under-correction of preoperative varus alignment does not lead to a difference in in-vivo bone loading in 3D-SPECT/CT compared to neutral alignment

BACKGROUND

The aim was to investigate the correlation of bone tracer uptake (BTU) in SPECT/CT and changes in coronal knee alignment after total knee arthroplasty (TKA). We questioned if undercorrection of preoperative varus alignment leads to a difference in BTU compared to neutral alignment.

METHODS

Consecutive 66 patients who received SPECT/CT before and after TKA were retrospectively included. Adjusted mechanical alignment was the alignment target. The alignment of the knee was measured on 3D-CT by selecting standardized landmarks. Maximum (mean ± SD) and relative BTU (ratio to the reference) were recorded using a previously validated localization scheme (p < 0.05).

RESULTS

In the native group, 20 knees were aligned (30.3%) in valgus (HKA > 181.5°), 12 (18.2%) in neutral (178.5°-181.5°) and 34 (51.5%) in varus (HKA < 178°). Overall TKA changed the alignment towards neutral. 48.5% remained in the same groups, whereas 50% of native valgus and 33% of varus knees changed to neutral after TKA. In native varus alignment mean BTU was significantly higher in some medial tibial and femoral regions (fem1ia (p = 0.010), fem1ip (p = 0.002), tib1a.mid (p = 0.005), tib1a.tray (p = 0.000), tib1p.tray (p = 0.000)); in native valgus alignment mean BTU was higher in the corresponding lateral tibial and femoral regions (fem2ip (p = 0.001), tib2a.tray (p = 0.011), tib2p.tray (p = 0.002)). After TKA, a significant decrease in femoral and tibial BTU (femoral preoperative BTU 1.64 +/-0.69; femoral postoperative BTU 0.95 +/-0.42; p = 0.000// tibial preoperative BTU 1.65 +/- 0.93; tibial postoperative BTU 1.16 +/- 0.48; p = 0.000) and an increase in patellar BTU was observed (p = 0.025). Native varus alignment correlated with a higher medial BTU decrease medially. Undercorrection of preoperative varus alignment showed no higher BTU after TKA.

CONCLUSION

Preoperative varus alignment correlated with a higher decrease in BTU in specific femoral and tibial medial regions. Preoperative valgus alignment correlated with a higher decrease in the corresponding lateral regions. Undercorrection of preoperative varus alignment did not lead to higher bone loading reflected by BTU after TKA.

The Extent of Task Specificity for Visual and Tactile Sequences in the Auditory Cortex of the Deaf and Hard of Hearing

It has been proposed that the auditory cortex in the deaf humans might undergo task-specific reorganization. However, evidence remains scarce as previous experiments used only two very specific tasks (temporal processing and face perception) in visual modality. Here, congenitally deaf/hard of hearing and hearing women and men were enrolled in an fMRI experiment as we sought to fill this evidence gap in two ways. First, we compared activation evoked by a temporal processing task performed in two different modalities, visual and tactile. Second, we contrasted this task with a perceptually similar task that focuses on the spatial dimension. Additional control conditions consisted of passive stimulus observation. In line with the task specificity hypothesis, the auditory cortex in the deaf was activated by temporal processing in both visual and tactile modalities. This effect was selective for temporal processing relative to spatial discrimination. However, spatial processing also led to significant auditory cortex recruitment which, unlike temporal processing, occurred even during passive stimulus observation. We conclude that auditory cortex recruitment in the deaf and hard of hearing might involve interplay between task-selective and pluripotential mechanisms of cross-modal reorganization. Our results open several avenues for the investigation of the full complexity of the cross-modal plasticity phenomenon.SIGNIFICANCE STATEMENT Previous studies suggested that the auditory cortex in the deaf may change input modality (sound to vision) while keeping its function (e.g., rhythm processing). We investigated this hypothesis by asking deaf or hard of hearing and hearing adults to discriminate between temporally and spatially complex sequences in visual and tactile modalities. The results show that such function-specific brain reorganization, as has previously been demonstrated in the visual modality, also occurs for tactile processing. On the other hand, they also show that for some stimuli (spatial) the auditory cortex activates automatically, which is suggestive of a take-over by a different kind of cognitive function. The observed differences in processing of sequences might thus result from an interplay of task-specific and pluripotent plasticity.

Synthetic Lethality in Cancer Therapeutics: The Next Generation

Synthetic lethality (SL) provides a conceptual framework for tackling targets that are not classically "druggable," including loss-of-function mutations in tumor suppressor genes required for carcinogenesis. Recent technological advances have led to an inflection point in our understanding of genetic interaction networks and ability to identify a wide array of novel SL drug targets. Here, we review concepts and lessons emerging from first-generation trials aimed at testing SL drugs, discuss how the nature of the targeted lesion can influence therapeutic outcomes, and highlight the need to develop clinical biomarkers distinct from those based on the paradigms developed to target activated oncogenes. SIGNIFICANCE: SL offers an approach for the targeting of loss of function of tumor suppressor and DNA repair genes, as well as of amplification and/or overexpression of genes that cannot be targeted directly. A next generation of tumor-specific alterations targetable through SL has emerged from high-throughput CRISPR technology, heralding not only new opportunities for drug development, but also important challenges in the development of optimal predictive biomarkers.

[Role of university hospitals in Bavaria during the COVID-19 pandemic]

Hintergrund

Anfang 2020 wurde deutschlandweit das Gesundheitswesen bedingt durch die coronavirus disease 2019 (COVID-19)-Pandemie auf einen Notbetrieb umgestellt. In Bayern wurde durch das zuständige Innen- und Gesundheitsministerium zu Beginn der ersten Welle eine Allgemeinverfügung erlassen, in der unter anderem die Organisation der Krankenhausbelegung, Neukonzeption der Informationstechnologie(IT)-Steuerung und Meldepflichten angeordnet wurden. Ziel dieser Auswertung war es, die Bedeutung der universitären Medizin für die stationäre Behandlung von COVID-19-Patienten in Bayern zu untersuchen.

Methoden

Es erfolgte eine retrospektive Auswertung aller stationär behandelten COVID-19-Patienten, die über das Modul IVENA Sonderlage (IVENA eHealth, [IVENA, interdisziplinärer Versorgungsnachweis, mainis IT-Service GmbH, Offenbach am Main, Deutschland]) gemeldet wurden. Hierbei wurden die gemeldeten Behandlungstage aller bayerischen Kliniken, die an der Versorgung von COVID-19-Patienten teilgenommen haben, ausgewertet.

Ergebnisse

Im Rahmen der ersten Welle der COVID-19-Pandemie wurden 90,9 % der Behandlungstage von kommunalen und öffentlichen sowie privaten Krankenhäusern in Bayern bereitgestellt. Neben der medizinischen Versorgung von COVID-19-Patienten mit komplexen Verläufen (20 % der Intensivstations[ICU]- und Intermediate-care-Stations [IMC]-Behandlungstage) leistete die Universitätsmedizin in Bayern mit ihren Kliniken einen relevanten wissenschaftlichen Beitrag und war wesentlich an der Beratung von Ärzten, Krankenhäusern und Politik zur Pandemie beteiligt.

DLSR: a solution to the parallax artefact in X-ray diffraction computed tomography data

A new tomographic reconstruction algorithm is presented, termed direct least-squares reconstruction (DLSR), which solves the well known parallax problem in X-ray-scattering-based experiments. The parallax artefact arises from relatively large samples where X-rays, scattered from a scattering angle 2θ, arrive at multiple detector elements. This phenomenon leads to loss of physico-chemical information associated with diffraction peak shape and position (i.e. altering the calculated crystallite size and lattice parameter values, respectively) and is currently the major barrier to investigating samples and devices at the centimetre level (scale-up problem). The accuracy of the DLSR algorithm has been tested against simulated and experimental X-ray diffraction computed tomography data using the TOPAS software.

Tracheal obstruction due to tumour: use of veno-venous extracorporeal membrane oxygenation during rigid bronchoscopy

Tracheal tumour is rare but can lead to upper airway obstruction and acute respiratory distress. Its management includes surgical resection, radiotherapy or interventional bronchoscopy. Ventilation or difficulties with tracheal intubation can occur during the peri-operative course resulting in serious adverse consequences. We report the case of an 83-year-old man with an obstructive tracheal chondrosarcoma resected by rigid bronchoscopy undergoing veno-venous extracorporeal membrane oxygenation. Such support should be considered when the patient's airway patency cannot be ensured by conventional methods.

A Genetic Map of the Response to DNA Damage in Human Cells

The response to DNA damage is critical for cellular homeostasis, tumor suppression, immunity, and gametogenesis. In order to provide an unbiased and global view of the DNA damage response in human cells, we undertook 31 CRISPR-Cas9 screens against 27 genotoxic agents in the retinal pigment epithelium-1 (RPE1) cell line. These screens identified 890 genes whose loss causes either sensitivity or resistance to DNA-damaging agents. Mining this dataset, we discovered that ERCC6L2 (which is mutated in a bone-marrow failure syndrome) codes for a canonical non-homologous end-joining pathway factor, that the RNA polymerase II component ELOF1 modulates the response to transcription-blocking agents, and that the cytotoxicity of the G-quadruplex ligand pyridostatin involves trapping topoisomerase II on DNA. This map of the DNA damage response provides a rich resource to study this fundamental cellular system and has implications for the development and use of genotoxic agents in cancer therapy.

Feed-forward neural networks using cerebral MR spectroscopy and DTI might predict neurodevelopmental outcome in preterm neonates

Objectives

We aimed to evaluate the ability of feed-forward neural networks (fNNs) to predict the neurodevelopmental outcome (NDO) of very preterm neonates (VPIs) at 12 months corrected age by using biomarkers of cerebral MR proton spectroscopy (¹H-MRS) and diffusion tensor imaging (DTI) at term-equivalent age (TEA).

Methods

In this prospective study, 300 VPIs born before 32 gestational weeks received an MRI scan at TEA between September 2013 and December 2017. Due to missing or poor-quality spectroscopy data and missing neurodevelopmental tests, 173 VPIs were excluded. Data sets consisting of 103 and 115 VPIs were considered for prediction of motor and cognitive developmental delay, respectively. Five metabolite ratios and two DTI characteristics in six different areas of the brain were evaluated. A feature selection algorithm was developed for receiving a subset of characteristics prevalent for the VPIs with a developmental delay. Finally, the predictors were constructed employing multiple fNNs and fourfold cross-validation.

Results

By employing the constructed fNN predictors, we were able to predict cognitive delays of VPIs with 85.7% sensitivity, 100% specificity, 100% positive predictive value (PPV) and 99.1% negative predictive value (NPV). For the prediction of motor delay, we achieved a sensitivity of 76.9%, a specificity of 98.9%, a PPV of 90.9% and an NPV of 96.7%.

Conclusion

FNNs might be able to predict motor and cognitive development of VPIs at 12 months corrected age when employing biomarkers of cerebral ¹H-MRS and DTI quantified at TEA.

Key Points

• A feed-forward neuronal network is a promising tool for outcome prediction in premature infants.

• Cerebral proton magnetic resonance spectroscopy and diffusion tensor imaging can be used for the construction of early prognostic biomarkers.

• Premature infants that would most benefit from early intervention services can be spotted at the time of optimal neuroplasticity.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-07053-8) contains supplementary material, which is available to authorized users.

Correlation Between Sarcopenia and Growth Rate of the Future Liver Remnant After Portal Vein Embolization in Patients with Colorectal Liver Metastases

PURPOSE

To investigate whether sarcopenia and myosteatosis correlate with the degree of hypertrophy (DH) and kinetic growth rate (KiGR) of the future liver remnant (FLR) in patients with colorectal liver metastases undergoing portal vein embolization (PVE) in preparation for right hepatectomy.

MATERIALS AND METHODS

Forty-two patients were included. Total liver volume and FLR volume were measured before and 2-4 weeks after PVE. KiGR of the FLR was calculated. Sarcopenia was assessed using the total psoas muscle volume (PMV), the psoas muscle cross-sectional area (PMCS) and the total skeletal muscle index (L3SMI) at the level of 3rd lumbar vertebra. Degree of myosteatosis was assessed by mean muscle attenuation at L3 (L3MA). Correlations between muscle indices and DH and KiGR were assessed using simple linear regression analyses.

RESULTS

Mean DH was 8.9 ± 5.7%, and mean KiGR was 3.6 ± 2.3. Mean PMV was 55.56 ± 14.19 cm3/m3, mean PMCS was 8.76 ± 2.3 cm2/m2, mean L3SMI was 45.6 ± 9.89 cm2/m2, and mean L3MA was 27.9 ± 18.6 HU. There was a strong positive correlation between PMV and DH (R = 0.503, p = 0.001) and PMV and KiGR (R = 0.545, p < 0.001). Furthermore, there was a moderate correlation between PMCS and KiGR (R = 0.389, p = 0.014). L3SMI and L3MA were neither associated with DH (p = 0.390 and p = 0.768, respectively) nor with KiGR (p = 0.188 and p = 0.929, respectively).

CONCLUSION

We identified a positive correlation between PMV and PMCS, as markers for sarcopenia, and the KiGR of the FLR after PVE. PMV and PMCS might therefore aid to identify patients who are poor candidates for FLR augmentation using PVE alone.

SAT0325 STELLATE BLOCKADE COMBINED TO ILOPROST AS SUPPORTIVE TREATMENT OPTION IMPROVES PAIN AND ISCHAEMIC SYMPTOMS IN PATIENTS WITH SYSTEMIC SCLEROSIS

Background:

Peripheral ischaemia is a common symptom in systemic sclerosis (SSc) patients with risk of development of digital ulcers (DU). For its treatment, intravenous iloprost is the most effective option. Accompanying pain symptoms worsen the ischaemic symptoms, so a combination with anaesthetic procedures may improve ischaemic status and the subjective sensation of raynaud and pain. The aim of this study was to observe the impact of a combined treatment of iloprost with stellate blockade (ILOST) in improvement of ischaemic symptoms compared to iloprost treatment only (ILO).

Objectives:

To evaluate efficacy of the ILOST treatment on changes in vascularisation and sensation of patients with SSc and indication for vasodilatative treatment with Iloprost.

Methods:

Twenty SSc-patients with indication for ILO-treatment (prophylactic or due to digital ulcerations (DU)) will be included in a prospective observational study. Patients will be offered to combine ILO with stellate blockade (ILOST). Beside documentation of disease activity characteristics (mRSS, number of DU, capillary microscopy at baseline, after ILO-treatment and at week 12), patients are assessed using fluorescence-optical imaging (FOI) as innovative method for illustration of changes in microvascularisation and patient reported outcomes (DASH, VAS) at week 12.

Results:

This interims analysis includes the result of the first 11 patients treated. Mean baseline characteristics (age and gender) are well balanced. Iloprost treatment was initiated due to prophylactic treatment to avoid DU in all patients. 100% of the patients in the ILOST-group were diagnosed as limited SSc compared to 60% in the ILO-group (diffuse type with 40%). All patients showed abnormalities in capillary microscopy (ILOST group: 83,3% late pattern 16.7% active pattern; ILO group: 80% late pattern, 20% early pattern). MRSS was low in both groups with 1.8, the disease duration in mean 15.3 years in the ILOST-group compared to 13.2 in the ILO-group, respectively. In both groups, no new DU occurred in the 12-week follow-up. Improvement in VAS pain was reported in 83% of the patients in the ILOST group compared to 60% in the ILO group. DASH improved with a mean of 5.5 points in the ILOST group compared to 3 points in the ILO group. FOI was compared individual at both arms in the ILOST group only. The arm with stellatum blockade showed a pronounced increase of FOI signals of 5% in mean whereas the opposite site showed a decrease of the signal shortly after ILO treatment indicating a pronounced increase of vascularisation in the ILOST treated body site.

Conclusion:

A new treatment approach to improve acute ischaemic symptoms was tested by combining stellate blockade to iloprost treatment. No new DU occurred up to 12 weeks after treatment in all patients of both groups indicating the relevance of iloprost as effective vascular dilatative therapy in SSc. The additional intervention was well tolerated and asked to repeat. Subjective sensation on pain of the hands as well as DASH was improved in the combined group. FOI showed a relevant increase in vascularisation in the blockade arm compared to the opposite site in which signals decreased indicating a stronger effect of the combined treatment for improvement of vascularisation.

Disclosure of Interests:

Franziska Höcketstaller Grant/research support from: Rheumazentrum Rhein-Main, Ulf Henkemeier: None declared, Michael Zimmermann: None declared, Harald Burkhardt Grant/research support from: Pfizer, Roche, Abbvie, Consultant of: Sanofi, Pfizer, Roche, Abbvie, Boehringer Ingelheim, UCB, Eli Lilly, Chugai, Bristol Myer Scripps, Janssen, and Novartis, Speakers bureau: Sanofi, Pfizer, Roche, Abbvie, Boehringer Ingelheim, UCB, Eli Lilly, Chugai, Bristol Myer Scripps, Janssen, and Novartis, Frank Behrens Grant/research support from: Pfizer, Janssen, Chugai, Celgene, Lilly and Roche, Consultant of: Pfizer, AbbVie, Sanofi, Lilly, Novartis, Genzyme, Boehringer, Janssen, MSD, Celgene, Roche and Chugai, Ulrich Drott: None declared, Michaela Köhm Grant/research support from: Pfizer, Janssen, BMS, LEO, Consultant of: BMS, Pfizer, Speakers bureau: Pfizer, BMS, Janssen, Novartis

Fatty Acid and Carnitine Metabolism Are Dysregulated in Systemic Sclerosis Patients

Systemic sclerosis (SSc) is a rare chronic disease of unknown pathogenesis characterized by fibrosis of the skin and internal organs, vascular alteration, and dysregulation of the immune system. In order to better understand the immune system and its perturbations leading to diseases, the study of the mechanisms regulating cellular metabolism has gained a widespread interest. Here, we have assessed the metabolic status of plasma and dendritic cells (DCs) in patients with SSc. We identified a dysregulated metabolomic signature in carnitine in circulation (plasma) and intracellularly in DCs of SSc patients. In addition, we confirmed carnitine alteration in the circulation of SSc patients in three independent plasma measurements from two different cohorts and identified dysregulation of fatty acids. We hypothesized that fatty acid and carnitine alterations contribute to potentiation of inflammation in SSc. Incubation of healthy and SSc dendritic cells with etoposide, a carnitine transporter inhibitor, inhibited the production of pro-inflammatory cytokines such as IL-6 through inhibition of fatty acid oxidation. These findings shed light on the altered metabolic status of the immune system in SSc patients and opens up for potential novel avenues to reduce inflammation.

High Pressure Liquid Chromatographic Determination of Glycyrrhizic Acid or Glycyrrhizic Acid Salts in Various Licorice Products: Collaborative Study

A collaborative study determining glycyrrhizic acid or glycyrrhizic acid salts content of various licorice products has been conducted using high pressure liquid chromatography (HPLC). Five samples containing various concentrations of glycyrrhizic acid were analyzed in blind replicates by 8 collaborators. The results indicate excellent repeatability and reproducibility with coefficients of variation less than 7.5%. In addition, this method allows the determination of glycyrrhizic acid in less than 15 min compared with 3 days for the conventional gravimetric and colorimetric methods. The method has been adopted official first action.

Novel insights into dendritic cells in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a severe autoimmune fibrotic disease characterized by fibrosis, vasculopathy, and immune dysregulation. Dendritic cells (DCs) are the most potent antigen-presenting cells, specialized in pathogen sensing, with high capacity to shape the immune responses. The most recent technological advances have allowed the discovery of new DC subsets with potential implications in inflammatory conditions. Alterations of DC distribution in circulation and affected tissue as well as impaired DC function have been described in SSc patients, pointing towards a crucial role of these cells in SSc pathogenesis. In particular, recent studies have shown the importance of plasmacytoid DCs either by their high capacity to produce type I interferon or other inflammatory mediators implicated in SSc pathology, such as chemokine C-X-C motif ligand 4 (CXCL4). In-vivo models of SSc have been vital to clarify the implications of DCs in this disease, especially DCs depletion and specific gene knock-down studies. This review provides these new insights into the contribution of the different DCs subsets in the pathogenesis of SSc, as well as to the novel developments on DCs in in-vivo models of SSc and the potential use of DCs and their mediators as therapeutic targets.

Influence of CAD/CAM Fabrication and Sintering Procedures on the Fracture Load of Full-Contour Monolithic Zirconia Crowns as a Function of Material Thickness

OBJECTIVE

The purpose of this in vitro study was to analyze the effect of computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication and sintering procedures on the fracture load of monolithic zirconia crowns with different material thicknesses adhesively seated to methacrylate dies fabricated with stereolithography technology.

METHOD

Monolithic zirconia crowns were fabricated from inCoris TZI C material with a chairside CAD/CAM system (CEREC MCXL) comprising three material thicknesses (0.5/1.0/1.5 mm, n=8 each). Two CAD/CAM fabrication procedures (milling, MI; grinding, GR), two chairside sintering procedures (superspeed, SS; speedfire sintering, SF), and one labside sintering procedure (classic, CL) were evaluated. In total, 144 crowns were fabricated. Restorations were adhesively seated to methacrylate dies fabricated with SLA technology. Thermomechanical cycling (TCML) was performed before fracture testing. Loading forces until fracture were registered and statistically analyzed with one-way analysis of variance (ANOVA), post hoc Scheffé test, and three-way ANOVA (α=0.05).

RESULTS

Test groups showed statistically significant differences (p<0.05). The highest mean value was found for 1.5-mm crowns of group GR_SF with 3678.6 ± 363.9 N. The lowest mean value was found for group 0.5-mm crowns of group MI_SF with 382.4 ± 30.7 N. There was a significant three-way interaction effect between thickness, sintering, and processing [F(4,126)=9.542; p<0.001; three-way ANOVA, significance level α=0.05].

CONCLUSIONS

CAD/CAM fabrication and sintering procedures influence the maximum loading force of monolithic zirconia crowns with different material thicknesses. A material thickness of 0.5 mm should be considered as a critical thickness for monolithic zirconia crown restorations.

Control of homologous recombination by the HROB-MCM8-MCM9 pathway

In this study, Hustedt et al. use CRISPR-based genetic screens to build a clear picture of the postsynaptic steps of homologous recombination in mammalian cells. They report the identification of C17orf53/HROB, a factor required for cell survival after exposure to a variety of replication stress-inducing genotoxins and for the resolution but not formation of Rad51 foci.

DNA repair by homologous recombination (HR) is essential for genomic integrity, tumor suppression, and the formation of gametes. HR uses DNA synthesis to repair lesions such as DNA double-strand breaks and stalled DNA replication forks, but despite having a good understanding of the steps leading to homology search and strand invasion, we know much less of the mechanisms that establish recombination-associated DNA polymerization. Here, we report that C17orf53/HROB is an OB-fold-containing factor involved in HR that acts by recruiting the MCM8–MCM9 helicase to sites of DNA damage to promote DNA synthesis. Mice with targeted mutations in Hrob are infertile due to depletion of germ cells and display phenotypes consistent with a prophase I meiotic arrest. The HROB–MCM8–MCM9 pathway acts redundantly with the HELQ helicase, and cells lacking both HROB and HELQ have severely impaired HR, suggesting that they underpin two major routes for the completion of HR downstream from RAD51. The function of HROB in HR is reminiscent of that of gp59, which acts as the replicative helicase loader during bacteriophage T4 recombination-dependent DNA replication. We therefore propose that the loading of MCM8–MCM9 by HROB may similarly be a key step in the establishment of mammalian recombination-associated DNA synthesis.

T^{3} Stern-Gerlach Matter-Wave Interferometer

We present a unique matter-wave interferometer whose phase scales with the cube of the time the atom spends in the interferometer. Our scheme is based on a full-loop Stern-Gerlach interferometer incorporating four magnetic field gradient pulses to create a state-dependent force. In contrast to typical atom interferometers that make use of laser light for the splitting and recombination of the wave packets, this realization uses no light and can therefore serve as a high-precision surface probe at very close distances.

Identifying chemogenetic interactions from CRISPR screens with drugZ

BACKGROUND

Chemogenetic profiling enables the identification of gene mutations that enhance or suppress the activity of chemical compounds. This knowledge provides insights into drug mechanism of action, genetic vulnerabilities, and resistance mechanisms, all of which may help stratify patient populations and improve drug efficacy. CRISPR-based screening enables sensitive detection of drug-gene interactions directly in human cells, but until recently has primarily been used to screen only for resistance mechanisms.

RESULTS

We present drugZ, an algorithm for identifying both synergistic and suppressor chemogenetic interactions from CRISPR screens. DrugZ identifies synthetic lethal interactions between PARP inhibitors and both known and novel members of the DNA damage repair pathway, confirms KEAP1 loss as a resistance factor for ERK inhibitors in oncogenic KRAS backgrounds, and defines the genetic context for temozolomide activity.

CONCLUSIONS

DrugZ is an open-source Python software for the analysis of genome-scale drug modifier screens. The software accurately identifies genetic perturbations that enhance or suppress drug activity. Interestingly, analysis of new and previously published data reveals tumor suppressor genes are drug-agnostic resistance genes in drug modifier screens. The software is available at github.com/hart-lab/drugz .

Short-Term Oral Sorafenib for Therapy of Intratumoral Shunts of Hepatocellular Carcinoma to Enable Intraarterial Treatment

INTRODUCTION

Significant intratumoral shunts between tumor-supplying arteries and portal or liver veins are a contraindication for transarterial therapy of HCC because interventional treatment of these shunts is frequently insufficient. Sorafenib has anti-angiogenic effects and is indicated for palliative treatment of patients with HCC. Here, we report our experience with the use of sorafenib for the closure of intratumoral shunts in patients scheduled for transarterial therapy of HCC.

MATERIALS AND METHODS

Three patients with HCC, aged 65, 82 and 79 years, exhibited a significant intratumoral shunting from tumor artery to portal (n = 1) or liver veins (n = 2). In all cases, intratumoral shunting had already been suspected based on pre-interventional CT angiography, and DSA confirmed the shunt. Oral sorafenib (800 mg/day) was administered for at least four weeks, only and specifically to occlude the shunt. Hereafter, patients were re-evaluated by CT and DSA.

RESULTS

All patients tolerated the full prescribed dose for at least 4 weeks. In one case, therapy was prolonged with an adapted dose (400 mg/day) due to sorafenib-related hand-foot syndrome. After sorafenib treatment, CT and DSA confirmed a complete closure of intratumoral shunts for all patients. No tumor progression was observed. All three patients hereafter underwent successful transarterial treatment by TACE (n = 2) or TARE (n = 1) without complications. Progression-free survival according to mRECIST was 501, 397 and 599 days, respectively.

CONCLUSION

Even short-term oral sorafenib seems to effectively close intratumoral shunts in patients with HCC and thus might enable transarterial treatment of these patients.

Abstract P1-08-32: Treatment delivery waiting times for stage I-III breast cancer patients in Switzerland : A pooled analysis of 7 cancer registries over the 2003-2008 period

Background: To examine time intervals between needle/core biopsy, breast cancer diagnosis, surgery and radiotherapy (RT) as quality metrics in the management of stage I-III breast cancer in a representative Swiss population sample.

Methods: Based on seven regional cancer registries covering 45% of the Swiss population, we identified 2628 women which underwent surgery for stage I-III breast cancer without receiving (neo)-adjuvant chemotherapy between January 1, 2003 and December 31, 2005.

Four different time intervals were defined: a) time between needle/core biopsy and diagnosis of breast cancer, b) time between diagnosis of breast cancer and surgery, c) time between needle/core biopsy and surgery, d) time between surgery and adjuvant RT.

These four time intervals were analyzed according to age, nationality, health insurance status, public vs. private hospitals and geography. We also investigated whether case discussion at tumor board delayed patient management.

A one-way analysis of variance (ANOVA) and multiple comparison tests were used to assess differences between groups. All tests were performed using STATA v.15.

Results: 2628 women were identified, median age was 67 years (IQR: 58-77). Breast-conserving surgery was performed in 1899 cases (72.3%), mastectomy in 539 cases (20.5%), unspecified surgery /missing data in 190 cases (7.2%). Adjuvant RT was delivered in 1546/2628 patients (58.8 %).

Time interval between biopsy and surgery was age-dependent, ranging from 22 days (95% CI: 19.6 - 25.2) for women &lt; 60 years to 39 days (95% CI: 27.0-50.3) for women 80+ years old (p&lt;0.001). After biopsy, women waited on average 19 days until surgery in private clinics (95% CI: 16.4-21.6) and 30 days in public hospitals (95% CI: 26.6-33.3) (p&lt;0.001). Women with private insurance were operated 24 days after biopsy (95% CI: 17.0-31.1), compared with 30 days (95% CI: 27.1-33.2) (p&lt;0.01)for women with basic state insurance. After biopsy, time interval for foreign nationals was significantly longer than for Swiss citizen (30 vs 24 days, p&lt;0.01). Tumor board presentation postponed surgery by 10 days (31 vs 22 days, p&lt;0.01).

Time between surgery and RT did not correlate with age (p=0.83); the interval was 33% longer in tertiary teaching hospitals than in private clinics (61 vs. 46 days, p&lt;0.001), and 8 days longer for patients with private insurance than for those without (61 vs 53 days, p&lt;0.01). There was a trend for foreign nationals to receive adjuvant RT later than Swiss citizen (58 vs 55 days, p=0.09). RT started later in larger metropolitan areas compared to more rural regions (59 vs 53 days, p&lt;0.01). Presenting patients at a tumor board after surgery had no impact on RT start (p=0.12).

Conclusions: Major differences in treatment waiting times were observed between patients with stage I-III breast cancer. Elderly and foreign patients were at risk for delayed surgery after biopsy. Data from patients with longer timelines need to be analyzed to identify further reasons for delays.

Citation Format: Zwahlen DR, Herrmann C, Mousavi M, Bordoni A, Bouchardy C, Konzelmann I, Staehlin K, Rohrmann S, Oehler C, Zimmermann M. Treatment delivery waiting times for stage I-III breast cancer patients in Switzerland : A pooled analysis of 7 cancer registries over the 2003-2008 period [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-32.

Accuracy of Buccal Scan Procedures for the Registration of Habitual Intercuspation

Clinical Relevance:

Accurate reproduction of the jaw relationship is important in many fields of dentistry. Maximum intercuspation can be registered with digital buccal scan procedures implemented in the workflow of many intraoral scanning systems.

Objective:

The aim of this study was to investigate the accuracy of buccal scan procedures with intraoral scanning devices for the registration of habitual intercuspation in vivo. The hypothesis was that there is no statistically significant difference for buccal scan procedures compared to registration methods with poured model casts.

Methods and Materials:

Ten individuals (full dentition, no dental rehabilitations) were subjects for five different habitual intercuspation registration methods: (CI) poured model casts, manual hand registration, buccal scan with inEOS X5; (BC) intraoral scan, buccal scan with CEREC Bluecam; (OC4.2) intraoral scan, buccal scan with CEREC Omnicam software version 4.2; (OC4.5β) intraoral scan, buccal scan with CEREC Omnicam version 4.5β; and (TR) intraoral scan, buccal scan with Trios 3. Buccal scan was repeated three times. Analysis of rotation (Rot) and translation (Trans) parameters was performed with difference analysis software (OraCheck). Statistical analysis was performed with one-way analysis of variance and the post hoc Scheffé test (p&lt;0.05).

Results:

Statistical analysis showed no significant (p&gt;0.05) differences in terms of translation between groups CI_Trans (98.74±112.01 μm), BC_Trans (84.12±64.95 μm), OC4.2_Trans (60.70±35.08 μm), OC4.5β_Trans (68.36±36.67 μm), and TR_Trans (66.60±64.39 μm). For rotation, there were no significant differences (p&gt;0.05) for groups CI_Rot (0.23±0.25°), BC_Rot (0.73±0.52°), OC4.2_Rot (0.45±0.31°), OC4.5β_Rot (0.50±0.36°), and TR_Rot (0.47±0.65°).

Conclusions:

Intraoral scanning devices allow the reproduction of the static relationship of the maxillary and mandibular teeth with the same accuracy as registration methods with poured model casts.

Patient's perception: shorter and more severe prodromal phase in GBA-associated PD

BACKGROUND

Prevalence and time of occurrence of prodromal symptoms of Parkinson's disease (PD) in relation to the onset of classical motor manifestation varies between patients. Possible modifying factors might be different genetic architectures predisposing to varying burden of manifestations.

OBJECTIVES

To characterize the prodromal phase in PD patients with heterozygous mutations in the GBA gene compared to PD patients without GBA mutation.

METHODS

In a retrospective design, 151 participants [47 PD patients carrying a GBA mutation (PD_GBA ), 52 idiopathic PD patients (PD_idiopathic ), 52 healthy elderly (CON)] underwent a validated structured interview designed to assess prevalence and time of occurrence of prodromal symptoms.

RESULTS

PD_GBA showed a higher prevalence of prodromal symptoms and almost simultaneous occurrence of non-motor and early motor symptoms shortly before PD diagnosis whereas PD_idiopathic reported a longer prodromal phase starting with non-motor symptoms.

CONCLUSION

The short and severe prodromal phase in PD_GBA might call for shorter assessment intervals in yet premanifest GBA mutation carriers.

Influence of Different CAM Strategies on the Fit of Partial Crown Restorations: A Digital Three-dimensional Evaluation

Objective:

CAM fabrication is an important step within the CAD/CAM process. The internal fit of restorations is influenced by the accuracy of the subtractive CAM procedure. Little is known about how CAM strategies might influence the fit of CAD/CAM fabricated restorations. The aim of this study was to three-dimensionally evaluate the fit of CAD/CAM fabricated zirconia-reinforced lithium silicate ceramic partial crowns fabricated with three different CAM strategies. The null hypothesis was that different CAM strategies did not influence the fitting accuracy of CAD/CAM fabricated zirconia-reinforced lithium silicate ceramic partial crowns.

Methods and Materials:

Preparation for a partial crown was performed on a maxillary right first molar on a typodont. A chairside CAD/CAM system with the intraoral scanning device CEREC Omnicam (Dentsply Sirona, York, PA, USA) and the 3+1 axis milling unit CEREC MCXL was used. There were three groups with different CAM strategies: step bur 12 (12), step bur 12S (12S), and two step-mode (12TWO). The zirconia-reinforced lithium silicate ceramic Celtra Duo (Dentsply Sirona) was used as the CAD/CAM material. A new 3D method for evaluating the fit was applied, consisting of the quadrant scan with the intraoral scanning device CEREC Omnicam. The scan of the PVS material adherent to the preparation and the preparation scan were matched, and the difference analysis was performed with special software OraCheck (Cyfex AG, Zurich, Switzerland). Three areas were selected for analysis: margin (MA), axial (AX), and occlusal (OC). Statistical analysis was performed using 80% percentile, one-way ANOVA, and the post hoc Scheffé test with α=0.05.

Results:

Statistically significant differences were found both within and between the test groups. The aspect axial fit results varied from 90.5 ± 20.1 μm for the two-step milling mode (12TWO_AX) to 122.8 ± 12.2 μm for the milling with step bur 12S (12S_AX). The worst result in all groups was found for the aspect occlusal fit with the highest value for group 12S of 222.8 ± 35.6 μm. Group two-step milling mode (12TWO) performed statistically significantly better from groups 12 and 12S for the occlusal fit (p&lt;0.05). Deviation patterns were visually analyzed with a color-coded scheme for each restoration.

Conclusions:

CAM strategy influenced the internal adaptation of zirconia-reinforced lithium silicate partial crowns fabricated with a chairside CAD/CAM system. Sensible selection of specific areas of internal adaptation and fit is an important factor for evaluating the CAM accuracy of CAD/CAM systems.

The shieldin complex mediates 53BP1-dependent DNA repair

53BP1 is a chromatin-binding protein that regulates the repair of DNA double-strand breaks by suppressing the nucleolytic resection of DNA termini1,2. This function of 53BP1 requires interactions with PTIP3 and RIF14-9, the latter of which recruits REV7 (also known as MAD2L2) to break sites10,11. How 53BP1-pathway proteins shield DNA ends is currently unknown, but there are two models that provide the best potential explanation of their action. In one model the 53BP1 complex strengthens the nucleosomal barrier to end-resection nucleases12,13, and in the other 53BP1 recruits effector proteins with end-protection activity. Here we identify a 53BP1 effector complex, shieldin, that includes C20orf196 (also known as SHLD1), FAM35A (SHLD2), CTC-534A2.2 (SHLD3) and REV7. Shieldin localizes to double-strand-break sites in a 53BP1- and RIF1-dependent manner, and its SHLD2 subunit binds to single-stranded DNA via OB-fold domains that are analogous to those of RPA1 and POT1. Loss of shieldin impairs non-homologous end-joining, leads to defective immunoglobulin class switching and causes hyper-resection. Mutations in genes that encode shieldin subunits also cause resistance to poly(ADP-ribose) polymerase inhibition in BRCA1-deficient cells and tumours, owing to restoration of homologous recombination. Finally, we show that binding of single-stranded DNA by SHLD2 is critical for shieldin function, consistent with a model in which shieldin protects DNA ends to mediate 53BP1-dependent DNA repair.

53BP1-RIF1-shieldin counteracts DSB resection through CST- and Polα-dependent fill-in

Resection of double-strand breaks (DSBs) dictates the choice between Homology-Directed Repair (HDR), which requires a 3′ overhang, and classical Non-Homologous End Joining (c-NHEJ), which can join unresected ends^1,2. BRCA1 mutant cancers show minimal DSB resection, rendering them HDR deficient and sensitive to PARP1 inhibitors (PARPi)^3–8. When BRCA1 is absent, DSB resection is thought to be prevented by 53BP1, Rif1, and the Rev7/Shld1/Shld2/Shld3 (Shieldin) complex and loss of these factors diminishes PARPi sensitivity^4,6–9. Here we address the mechanism by which 53BP1/Rif1/Shieldin regulate the generation of recombinogenic 3′ overhangs. We report that CST (Ctc1, Stn1, Ten1¹⁰), an RPA-like complex that functions as a Polymeraseα/primase accessory factor¹¹ is a downstream effector in the 53BP1 pathway. CST interacts with Shieldin and localizes with Polα to sites of DNA damage in a 53BP1- and Shieldin-dependent manner. Like loss of 53BP1/Rif1/Shieldin, CST depletion leads to increased resection. Furthermore, in BRCA1-deficient cells, CST blocks Rad51 loading and promotes PARPi efficacy. Finally, Polα inhibition diminishes the effect of PARPi in BRCA1-deficient cells. These data suggest that CST/Polα-mediated fill-in contributes to the control of DSB repair by 53BP1, Rif1, and Shieldin.

Membrana de látex natural de Hevea brasiliensis auxilia no processo de reparação tecidual em bovinos

RESUMO Feridas cutâneas em bovinos são um constante desafio clínico cirúrgico por desencadearem perdas econômicas bastante significativas. O látex proveniente da seiva da seringueira (Hevea brasiliensis) apresenta potencial terapêutico para incrementar o processo de reparação tecidual. Portanto, pretendeu-se com esse estudo avaliar o tipo de reação tecidual e os possíveis mecanismos de angiogênese desencadeados pelo implante de uma membrana de látex natural em bovinos. Para tal, foram utilizados seis bovinos da raça Nelore, submetidos ao implante subcutâneo experimental de três fragmentos de membranas de látex natural. Foram coletadas amostras de tecido e da membrana aos 15, 30 e 45 dias após a implantação, para avaliações histológicas, ultraestruturais por microscopia eletrônica de varredura e imunoistoquímicas com anticorpos antimarcador de macrófagos (MAC), CYR 61 e VEGF. O implante de látex proporcionou aumento da angiogênese e reparação tecidual em bovinos, não mediada pela expressão do VEGF e CYR 61.

Generation of 3-dimensional multi-patches on silica particles via printing with wrinkled stamps

A simple route towards patchy particles with anisotropic patches with respect to a different functionality and directionality is presented. This method is based on microcontact printing of positively charged polyethylenimine (PEI) on silica particles using wrinkled stamps. Due to the wrinkled surface, the number of patches on the particles as well as the distance between two patches can be controlled.

Substrate and electron donor limitation induce phenotypic heterogeneity in different metabolic activities in a green sulphur bacterium

Populations of genetically identical cells can display marked variation in phenotypic traits; such variation is termed phenotypic heterogeneity. Here, we investigate the effect of substrate and electron donor limitation on phenotypic heterogeneity in N₂ and CO₂ fixation in the green sulphur bacterium Chlorobium phaeobacteroides. We grew populations in chemostats and batch cultures and used stable isotope labelling combined with nanometer-scale secondary ion mass spectrometry (NanoSIMS) to quantify phenotypic heterogeneity. Experiments in H₂ S (i.e. electron donor) limited chemostats show that varying levels of NH4+ limitation induce heterogeneity in N₂ fixation. Comparison of phenotypic heterogeneity between chemostats and batch (unlimited for H₂ S) populations indicates that electron donor limitation drives heterogeneity in N₂ and CO₂ fixation. Our results demonstrate that phenotypic heterogeneity in a certain metabolic activity can be driven by different modes of limitation and that heterogeneity can emerge in different metabolic processes upon the same mode of limitation. In conclusion, our data suggest that limitation is a general driver of phenotypic heterogeneity in microbial populations.

MN1 overexpression is driven by loss of DNMT3B methylation activity in inv(16) pediatric AML

In acute myeloid leukemia (AML), specific genomic aberrations induce aberrant methylation, thus directly influencing the transcriptional programing of leukemic cells. Therefore, therapies targeting epigenetic processes are advocated as a promising therapeutic tool for AML treatment. However, to develop new therapies, a comprehensive understanding of the mechanism(s) driving the epigenetic changes as a result of acquired genetic abnormalities is necessary. This understanding is still lacking. In this study, we performed genome-wide CpG-island methylation profiling on pediatric AML samples. Six differentially methylated genomic regions within two genes, discriminating inv(16)(p13;q22) from non-inv(16) pediatric AML samples, were identified. All six regions had a hypomethylated phenotype in inv(16) AML samples, and this was most prominent at the regions encompassing the meningioma (disrupted in balanced translocation) 1 (MN1) oncogene. MN1 expression primarily correlated with the methylation level of the 3' end of the MN1 exon-1 locus. Decitabine treatment of different cell lines showed that induced loss of methylation at the MN1 locus can result in an increase of MN1 expression, indicating that MN1 expression is coregulated by DNA methylation. To investigate this methylation-associated mechanism, we determined the expression of DNA methyltransferases in inv(16) AML. We found that DNMT3B expression was significantly lower in inv(16) samples. Furthermore, DNMT3B expression correlated negatively with MN1 expression in pediatric AML samples. Importantly, depletion of DNMT3B impaired remethylation efficiency of the MN1 exon-1 locus in AML cells after decitabine exposure. These findings identify DNMT3B as an important coregulator of MN1 methylation. Taken together, this study shows that the methylation level of the MN1 exon-1 locus regulates MN1 expression levels in inv(16) pediatric AML. This methylation level is dependent on DNMT3B, thus suggesting a role for DNMT3B in leukemogenesis in inv(16) AML, through MN1 methylation regulation.

Kontrolle der Thrombozytenaggregationshemmung unter Therapie mit Azetylsalizylsäure und/oder Clopidogrel mit einem modifizierten Thrombozytenaggregationstest

Patienten mit Atherothrombose erhalten prophylaktisch ASS und/oder Clopidogrel zur Hemmung der Plättchenaggregation. Es wurde untersucht, ob ein aggregometrisches Verfahren den Effekt aggregationshemmender Substanzen (ASS 30, 50, 100, 300 mg/d, Clopidogrel 75 mg/d oder ASS 100 + Clopidogrel 75 mg/d) abbilden kann. Ein modifizierter Plättchenaggregationstest diente der Bestimmung der maximalen Aggregation nach Induktion mit ADP, Kollagen, Adrenalin und Arachidonsäure. Aus Werten eines gesunden Kollektivs wurden Referenzwerte abgeleitet und ein einfaches System zur Detektion inadäquater Plättchenhemmung entwickelt. Im Vergleich zur Kontrollgruppe zeigte sich eine signifikante Hemmung der maximalen Aggregation mit allen Induktoren bei Patienten unter ASS und der Kombination ASS + Clopidogrel. Bei Patienten unter Clopidogrel fand sich eine Hemmung der Aggregation nach Induktion mit ADP, Kollagen und Arachidonsäure. Unter 100 mg ASS/d trat eine ungenügende Hemmung bei 27%, unter 75 mg Clopidogrel/d bei 26% und unter der Kombinationstherapie bei 7% der Patienten auf. Die Ergebnisse zeigen, dass bei vielen Patienten mit arteriellen Thrombosen eine inadäquate Plättchenhemmung vorliegt.