Development of a high brightness ultrafast Transmission Electron Microscope based on a laser-driven cold field emission source

We report on the development of an ultrafast Transmission Electron Microscope based on a cold field emission source which can operate in either DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses which are tightly focused by optical components integrated inside a cold field emission source close to the cathode. The properties of the electron probe (brightness, angular current density, stability) are quantitatively determined. The measured brightness is the largest reported so far for UTEMs. Examples of imaging, diffraction and spectroscopy using ultrashort electron pulses are given. Finally, the potential of this instrument is illustrated by performing electron holography in the off-axis configuration using ultrashort electron pulses.

Patient-derived xenografts of gastrointestinal cancers are susceptible to rapid and delayed B-lymphoproliferation

Patient-derived cancer xenografts (PDX) are widely used to identify and evaluate novel therapeutic targets, and to test therapeutic approaches in preclinical mouse avatar trials. Despite their widespread use, potential caveats of PDX models remain considerably underappreciated. Here, we demonstrate that EBV-associated B-lymphoproliferations frequently develop following xenotransplantation of human colorectal and pancreatic carcinomas in highly immunodeficient NOD.Cg-Prkdc^scid Il2rg^tm1Wjl /SzJ (NSG) mice (18/47 and 4/37 mice, respectively), and in derived cell cultures in vitro. Strikingly, even PDX with carcinoma histology can host scarce EBV-infected B-lymphocytes that can fully overgrow carcinoma cells during serial passaging in vitro and in vivo. As serial xenografting is crucial to expand primary tumor tissue for biobanks and cohorts for preclinical mouse avatar trials, the emerging dominance of B-lymphoproliferations in serial PDX represents a serious confounding factor in these models. Consequently, repeated phenotypic assessments of serial PDX are mandatory at each expansion step to verify "bona fide" carcinoma xenografts.

Genetic subclone architecture of tumor clone-initiating cells in colorectal cancer

Combining high-coverage whole-genome sequencing with functional analyses, Giessler et al. demonstrate that tumor initiation and long-term tumor formation in human colorectal cancer are driven by multiple genomic subclones and that the functional heterogeneity of colorectal cancer tumor clone–initiating cells is not based on genomic architecture.

A hierarchically organized cell compartment drives colorectal cancer (CRC) progression. Genetic barcoding allows monitoring of the clonal output of tumorigenic cells without prospective isolation. In this study, we asked whether tumor clone-initiating cells (TcICs) were genetically heterogeneous and whether differences in self-renewal and activation reflected differential kinetics among individual subclones or functional hierarchies within subclones. Monitoring genomic subclone kinetics in three patient tumors and corresponding serial xenografts and spheroids by high-coverage whole-genome sequencing, clustering of genetic aberrations, subclone combinatorics, and mutational signature analysis revealed at least two to four genetic subclones per sample. Long-term growth in serial xenografts and spheroids was driven by multiple genomic subclones with profoundly differing growth dynamics and hence different quantitative contributions over time. Strikingly, genetic barcoding demonstrated stable functional heterogeneity of CRC TcICs during serial xenografting despite near-complete changes in genomic subclone contribution. This demonstrates that functional heterogeneity is, at least frequently, present within genomic subclones and independent of mutational subclone differences.

Correlation of endoscopic disease severity with pediatric ulcerative colitis activity index score in children and young adults with ulcerative colitis

AIM

To investigate of pediatric ulcerative colitis activity index (PUCAI) in ulcerative colitis correlate with mucosal inflammation and endoscopic assessment of disease activity (Mayo endoscopic score).

METHODS

We reviewed charts from ulcerative colitis patients who had undergone both colonoscopy over 3 years. Clinical assessment of disease severity within 35 d (either before or after) the colonoscopy were included. Patients were excluded if they had significant therapeutic interventions (such as the start of corticosteroids or immunosuppressive agents) between the colonoscopy and the clinical assessment. Mayo endoscopic score of the rectum and sigmoid were done by two gastroenterologists. Inter-observer variability in Mayo score was assessed.

RESULTS

We identified 99 patients (53% female, 74% pancolitis) that met inclusion criteria. The indications for colonoscopy included ongoing disease activity (62%), consideration of medication change (10%), assessment of medication efficacy (14%), and cancer screening (14%). Based on PUCAI scores, 33% of patients were in remission, 39% had mild disease, 23% had moderate disease, and 4% had severe disease. There was “moderate-substantial” agreement between the two reviewers in assessing rectal Mayo scores (kappa = 0.54, 95%CI: 0.41-0.68).

CONCLUSION

Endoscopic disease severity (Mayo score) assessed by reviewing photographs of pediatric colonoscopy has moderate inter-rater reliability, and agreement was less robust in assessing patients with mild disease activity. Endoscopic disease severity generally correlates with clinical disease severity as measured by PUCAI score. However, children with inflamed colons can have significant variation in their reported clinical symptoms. Thus, assessment of both clinical symptoms and endoscopic disease severity may be required in future clinical studies.

Transition from Collisional to Collisionless Regimes in Interpenetrating Plasma Flows on the National Ignition Facility

A study of the transition from collisional to collisionless plasma flows has been carried out at the National Ignition Facility using high Mach number (M>4) counterstreaming plasmas. In these experiments, CD-CD and CD-CH planar foils separated by 6-10 mm are irradiated with laser energies of 250 kJ per foil, generating ∼1000  km/s plasma flows. Varying the foil separation distance scales the ion density and average bulk velocity and, therefore, the ion-ion Coulomb mean free path, at the interaction region at the midplane. The characteristics of the flow interaction have been inferred from the neutrons and protons generated by deuteron-deuteron interactions and by x-ray emission from the hot, interpenetrating, and interacting plasmas. A localized burst of neutrons and bright x-ray emission near the midpoint of the counterstreaming flows was observed, suggesting strong heating and the initial stages of shock formation. As the separation of the CD-CH foils increases we observe enhanced neutron production compared to particle-in-cell simulations that include Coulomb collisions, but do not include collective collisionless plasma instabilities. The observed plasma heating and enhanced neutron production is consistent with the initial stages of collisionless shock formation, mediated by the Weibel filamentation instability.

The molluscum contagiosum virus death effector domain containing protein MC160 RxDL motifs are not required for its known viral immune evasion functions

The molluscum contagiosum virus (MCV) uses a variety of immune evasion strategies to antagonize host immune responses. Two MCV proteins, MC159 and MC160, contain tandem death effector domains (DEDs). They are reported to inhibit innate immune signaling events such as NF-κB and IRF3 activation, and apoptosis. The RxDL motif of MC159 is required for inhibition of both apoptosis and NF-κB activation. However, the role of the conserved RxDL motif in the MC160 DEDs remained unknown. To answer this question, we performed alanine mutations to neutralize the arginine and aspartate residues present in the MC160 RxDL in both DED1 and DED2. These mutations were further modeled against the structure of the MC159 protein. Surprisingly, the RxDL motif was not required for MC160's ability to inhibit MAVS-induced IFNβ activation. Further, unlike previous results with the MC159 protein, mutations within the RxDL motif of MC160 had no effect on the ability of MC160 to dampen TNF-α-induced NF-κB activation. Molecular modeling predictions revealed no overall changes to the structure in the MC160 protein when the amino acids of both RxDL motifs were mutated to alanine (DED1 = R67A D69A; DED2 = R160A D162A). Taken together, our results demonstrate that the RxDL motifs present in the MC160 DEDs are not required for known functions of the viral protein.

Measurement system for temperature dependent noise characterization of magnetoresistive sensors

Magnetoresistive (MR) sensors and sensor systems are used in a large variety of applications in the field of industrial automation, automotive business, aeronautic industries, and instrumentation. Different MR sensor technologies like anisotropic magnetoresistive, giant magnetoresistive, and tunnel magnetoresistive sensors show strongly varying properties in terms of magnetoresistive effect, response to magnetic fields, achievable element miniaturization, manufacturing effort, and signal-to-noise ratio. Very few data have been reported so far on the comparison of noise performance for different sensor models and technologies, especially including the temperature dependence of their characteristics. In this paper, a stand-alone measurement setup is presented that allows a comprehensive characterization of MR sensors including sensitivity and noise over a wide range of temperatures.

Role of Frequency Chirp and Energy Flow Directionality in the Strong Coupling Regime of Brillouin-Based Plasma Amplification

A detailed analysis is presented of the various stages of strong coupling Brillouin plasma amplification, emphasizing the importance of the chirp which can be of threefold origin: the intrinsic one driven by the amplification process, the one originating from the chirped-pulse-generated laser pulses, and the one associated with the plasma profile. Control of the overall chirp can optimize or quench the energy transfer. The time-dependent phase relation explains the energy flow direction during amplification and is characteristic for this strong coupling process. The study is also of potential importance to understand and maybe control cross-beam-energy transfer in inertial confinement fusion.

A microwave resonator integrated on a polymer microfluidic chip

We describe a novel stacked split-ring type microwave (MW) resonator that is integrated into a 10mm by 10mm sized microfluidic chip. A straightforward and scalable batch fabrication process renders the chip suitable for single-use applications. The resonator volume can be conveniently loaded with liquid sample via microfluidic channels patterned into the mid layer of the chip. The proposed MW resonator offers an alternative solution for compact in-field measurements, such as low-field magnetic resonance (MR) experiments requiring convenient sample exchange. A microstrip line was used to inductively couple MWs into the resonator. We characterised the proposed resonator topology by electromagnetic (EM) field simulations, a field perturbation method, as well as by return loss measurements. Electron paramagnetic resonance (EPR) spectra at X-band frequencies were recorded, revealing an electron-spin sensitivity of 3.7·10(11)spins·Hz(-1/2)G(-1) for a single EPR transition. Preliminary time-resolved EPR experiments on light-induced triplet states in pentacene were performed to estimate the MW conversion efficiency of the resonator.

Vascularization of malignant and benign skin tumours measured by d-galactose-based signal-enhanced colour doppler sonography

Purpose: Evaluation of colour Doppler criteria to differentiate between malignant and benign skin tumours on the basis of the degree of vascularization.

Material and Methods: The B-mode sonomorphology and the degree of vascularization in colour Doppler of 81 clinically potentially malignant tumours of cutaneous and subcutaneous structures were analyzed and quantified by number of intratumoral vessels per sonographic slice and percentage vessel area.

Results: Of all criteria employed, counting the intratumoral vessels visible on one ultrasound slice after application of a signal-enhancing agent led to highest sensitivity (94%) of all used criteria but the specificity was poor (64%). The highest specificity (88%) and greatest diagnostic accuracy (86%) discriminating benign and malignant lesions were found using the criterion "percentage vessel area >5.0%" after all inflamed lesions had been excluded on the basis of clinical criteria. Plain colour Doppler increased the specificity up to 97%, although the sensitivity decreased simultaneously to max. 75%. Analysis of the B-mode morphology and spectral Doppler parameter of intratumoral vessels did not contribute to the differential diagnosis.

Conclusion: Signal-enhanced colour Doppler sonography is a valuable tool in the pretherapeutic assessment of cutaneous lesions. This method may be relevant for therapy and prognosis.

Abstract 910: Genetic subclone heterogeneity of the human colon cancer initiating cell compartment

A subpopulation of tumor-initiating cells (TIC) drives colorectal cancer (CRC) progression in serial xenotransplantation. Strikingly, the CRC TIC compartment itself is heterogeneous and comprised of a hierarchy of long-term (LT-) TIC, tumor transient amplifying cells (T-TAC) and delayed contributing (DC-) TIC. Whether this functionally heterogeneous TIC compartment is genetically homogenous or whether distinct genetic subclones drive the functional heterogeneity of the TIC compartment is yet unknown. To address this question, we performed high coverage (91-126 fold) whole genome sequencing on primary CRC patient tumors (n = 3), corresponding serially passaged TIC enriched spheroids as well as spheroid derived serial xenografts. Sequenced samples harbored between 22.800 and 232.000 synonymous or non-synonymous single nucleotide variants (SNVs). In addition, all samples contained multiple focal or large-scale somatic copy number alterations (CNAs). Clustering of SNVs as well as subclonal copy numbers from serial xenografts and spheroids were used to define SNV- and CNA-based subpopulations. Next, cellular fractions of identified subpopulations were determined and combined applying maximal parsimony to create models of the minimal number of subclones present in each sample. Using this strategy, we found that multiple subclones were present in each sample analyzed. Subclone heterogeneity was maintained during serial in vitro passaging and serial xenografting. Importantly, tumor initiation in xenografts was driven by at least 3 distinct genetic subclones whose relative contribution dynamically changed over time. Strikingly, in serial samples from the same patients, different genetic subclones grew out in vivo and in vitro.

To test whether functional heterogeneity of the TIC compartment is related to the presence of genetic subclones, we assessed the contribution of different TIC subtypes - LT-TIC, T-TAC and DC-TIC - at early and late time points of xenografting using secondary genetic marking. Therefore, 1×10⁁5 cells derived from early and late generation xenografts were transduced with an integrating lentiviral vector, thereby generating a stable barcode-like genetic mark which differs in each transduced cell. Following serial transplantation of transduced cells for 3 mouse generations, tumors were harvested and lentiviral integration sites were determined using highly sensitive LAM-PCR and high-throughput sequencing. Assessing the relative contribution of LT-TIC, T-TAC and DC-TIC revealed that the functional heterogeneity of the TIC compartment was preserved despite profound genetic subclone dynamics in serial xenotransplantation. These results strongly indicate that multiple genetic subclones drive long-term tumor formation and that functional heterogeneity of the CRC TIC compartment is not based on specific genetic subclones.

Citation Format: Klara M. Giessler, Kortine Kleinheinz, Gnana Prakash Balasubramanian, Daniel Hübschmann, Taronish D. Dubash Rai, Sebastian D. Dieter, Christine Siegl, Christopher M. Hoffmann, Sarah Weber, Raffaele Fronza, Saira Afzal, Manfred Schmidt, Martin Schneider, Alexis Ulrich, Juergen Weitz, Wilko Weichert, Matthias Schlesner, Benedikt Brors, Claudia R. Ball, Hanno Glimm. Genetic subclone heterogeneity of the human colon cancer initiating cell compartment. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 910.

Postoperative Color Flow Duplex Scanning in Aortic Endografting

Purpose:

To report the feasibility and sensitivity of duplex sonography compared to computed tomography (CT) for aortic endograft follow-up surveillance.

Methods:

In a 26-month period, 113 aortic aneurysm patients received 79 tube and 34 bifurcated stent-grafts. Follow-up used contrast-enhanced CT scanning and duplex sonography with an intravenous ultrasound contrast agent (Levovist).

Results:

Eleven patients (9.7%) were converted to open repair; 1 died from hemorrhagic shock secondary to retroperitoneal hematoma. The mean follow-up time was 7.2 months (range 1 to 24), during which 5 patients died of unrelated causes. Sixteen primary (within 30 days) and 5 secondary endoleaks were detected by duplex after tube graft implantation. Among 5 endoleaks due to retrograde side-branch perfusion, 3 were detected only with contrast-enhanced duplex scanning. Iliac artery occlusion was also documented using duplex; however, 2 stent fractures could not be seen with ultrasound. Ten primary endoleaks were detected in bifurcated stent-graft patients. One endoleak originating from the distal iliac limb anchoring site was missed by duplex owing to bowel gas. Graft limb thrombosis was clearly identified by lack of a flow signal on duplex.

Conclusions:

Duplex sonography could be a valuable, reliable, and economical surveillance tool for endovascular aortic reconstructions. The adjunctive use of an intravenous ultrasound contrast agent increased the sensitivity for detecting endoleak to a level comparable to contrast-enhanced CT scanning. However, stent fractures may not be seen on ultrasound, and bowel gas can interfere with obtaining an adequate image.

[Pioneering surgical innovations in Germany : Part 2: public funding and origins of surgical innovations]

BACKGROUND

In recent years research that conforms with evidence-based medicine (EBM) has been demanded even in surgery. Uniform studies were carried out to prove the benefits of new procedures; however, compared to other research sectors, public third party funding for surgical research was significantly cut back.

OBJECTIVE

Collation of special features in surgery with respect to external funding of surgical top level research. Examination of the benefits of a continuous promotion and of organizations involved in research.

MATERIAL AND METHODS

Part one of this investigation presented the methods used to identify and analyze pioneering research in surgery.

RESULTS

Out of a total of 15 revolutionary innovations only 3 projects were financed by external funding and 2 projects received indirect financial support as a result of a cooperation with the medical industry. This demonstrates that the majority of projects were neither directly nor indirectly subsidized. Apart from one instance the majority of innovations were generated by university hospitals highly active in research.

DISCUSSION

In effect, the non-existing external funding for outstanding surgical innovations and hospitals suggests that a reformation of surgical research is required. To strengthen the quality of innovations in surgery a concentration of funding to institutions that are highly active in research makes sense. Institutional funding directly linked to a project should form a key component of support particularly in the early stages of development.

Signatures of the Self-Similar Regime of Strongly Coupled Stimulated Brillouin Scattering for Efficient Short Laser Pulse Amplification

Plasma-based laser amplification is considered as a possible way to overcome the technological limits of present day laser systems and achieve exawatt laser pulses. Efficient amplification of a picosecond laser pulse by stimulated Brillouin scattering (SBS) of a pump pulse in a plasma requires to reach the self-similar regime of the strongly coupled (SC) SBS. In this Letter, we report on the first observation of the signatures of the transition from linear to self-similar regimes of SC-SBS, so far only predicted by theory and simulations. With a new fully head-on collision geometry, subpicosecond pulses are amplified by a factor of 5 with energy transfers of few tens of mJ. We observe pulse shortening, frequency spectrum broadening, and down-shifting for increasing gain, signatures of SC-SBS amplification entering the self-similar regime. This is also confirmed by the power law dependence of the gain on the amplification length: doubling the interaction length increases the gain by a factor 1.4. Pump backward Raman scattering (BRS) on SC-SBS amplification has been measured for the first time, showing a strong decrease of the BRS amplitude and frequency bandwidth when SBS seed amplification occurs.