Multiexcitonic and optically bright states in subunits of pentacene crystals: A hybrid DFT/MRCI and molecular mechanics study

A hybrid quantum mechanics/molecular mechanics setup was used to model electronically excited pentacene in the crystal phase. Particularly interesting in the context of singlet fission (SF) is the energetic location of the antiferromagnetically coupled multiexcitonic singlet state, 1(TT), and the ferromagnetically coupled analog in relation to the optically bright singlet state. To provide photophysical properties of the accessible spin manifold, combined density functional theory and multi-reference configuration interaction calculations were performed on pentacene dimers and a trimer, electrostatically embedded in the crystal. The likelihood of a quintet intermediate in the SF process was estimated by computing singlet-quintet electron spin-spin couplings employing the Breit-Pauli Hamiltonian. The performance of the applied methods was assessed on the pentacene monomer. The character of the optically bright state and the energetic location of the 1(TT) state depend strongly on the relative orientation of the pentacene units. In the V-shaped dimers and in the trimer, the optically bright state is dominated by local and charge transfer (CT) excitations, with admixtures of doubly excited configurations. The CT excitations gain weight upon geometry relaxation, thus supporting a CT-mediated SF mechanism as the primary step of the SF process. For the slip-stacked dimer, the energetic order of the bright and the 1(TT) states swaps upon geometry relaxation, indicating strong nonadiabatic coupling close to the Franck-Condon region-a prerequisite for a coherent SF process. The multiexcitonic singlet, triplet, and quintet states are energetically too far apart and their spin-spin couplings are too small to bring about a noteworthy multiplicity mixing.

The dissociation of (a+c) misfit dislocations at the InGaN/GaN interface

In hexagonal materials, (a+c) dislocations are typically observed to dissociate into partial dislocations. Edge (a+c) dislocations are introduced into (0001) nitride semiconductor layers by the process of plastic relaxation. As there is an increasing interest in obtaining relaxed InGaN buffer layers for the deposition of high In content structures, the study of the dissociation mechanism of misfit (a+c) dislocations laying at the InGaN/GaN interface is then crucial for understanding their nucleation and glide mechanisms. In the case of the presented plastically relaxed InGaN layers deposited on GaN substrates, we observe a trigonal network of (a+c) dislocations extending at the interface with a rotation of 3° from <11 ¯ $\bar 1$ 00> directions. High-resolution microscopy studies show that these dislocations are dissociated into two Frank-Shockley 1/6<22 ¯ $\bar 2$ 03> partial dislocations with the I1 BSF spreading between them. Atomistic simulations of a dissociated edge (a+c) dislocation revealed a 3/5-atom ring structure for the cores of both partial dislocations. The observed separation between two partial dislocations must result from the climb of at least one of the dislocations during the dissociation process, possibly induced by the mismatch stress in the InGaN layer.

Demonstrating Agreement between Radio and Fluorescence Measurements of the Depth of Maximum of Extensive Air Showers at the Pierre Auger Observatory

We show, for the first time, radio measurements of the depth of shower maximum (X_{max}) of air showers induced by cosmic rays that are compared to measurements of the established fluorescence method at the same location. Using measurements at the Pierre Auger Observatory we show full compatibility between our radio and the previously published fluorescence dataset, and between a subset of air showers observed simultaneously with both radio and fluorescence techniques, a measurement setup unique to the Pierre Auger Observatory. Furthermore, we show radio X_{max} resolution as a function of energy and demonstrate the ability to make competitive high-resolution X_{max} measurements with even a sparse radio array. With this, we show that the radio technique is capable of cosmic-ray mass composition studies, both at Auger and at other experiments.

Avapritinib-based SAR studies unveil a binding pocket in KIT and PDGFRA

Avapritinib is the only potent and selective inhibitor approved for the treatment of D842V-mutant gastrointestinal stromal tumors (GIST), the most common primary mutation of the platelet-derived growth factor receptor α (PDGFRA). The approval was based on the NAVIGATOR trial, which revealed overall response rates of more than 90%. Despite this transformational activity, patients eventually progress, mostly due to acquired resistance mutations or following discontinuation due to neuro-cognitive side effects. These patients have no therapeutic alternative and face a dismal prognosis. Notable, little is known about this drug's binding mode and its medicinal chemistry development, which is instrumental for the development of the next generation of drugs. Against this background, we solve the crystal structures of avapritinib in complex with wild-type and mutant PDGFRA and stem cell factor receptor (KIT), which provide evidence and understanding of inhibitor binding and lead to the identification of a sub-pocket (Gα-pocket). We utilize this information to design, synthesize and characterize avapritinib derivatives for the determination of key pharmacophoric features to overcome drug resistance and limit potential blood-brain barrier penetration.

Electron affinities and lowest triplet and singlet state properties of para-oligophenylenes (n = 3-5): theory and experiment

We apply photodetachment-photoelectron spectroscopy to measure the electron affinities and the energetics of the lowest excited electronic states of the neutral molecules para-terphenyl (p3P), para-quaterphenyl (p4P) and para-quinquephenyl (p5P), including especially the triplet states below S1. The interpretation of the experimental data is based on the comparison to calculated 0-0 energies and Dyson norms, using density functional theory and multireference configuration interaction methods, as well as Franck-Condon patterns. The comparison between calculated and experimental vibrational fine-structures reveals a twisted benzoid-like molecular structure of the S0 ground state and nearly planar quinoid-like nuclear arrangements in the S1 and T1 excited states as well as in the D0 anion ground state. For all para-oligophenylenes (ppPs) in this series, at least two triplet states have been identified in the energy regime below the S1 state. The large optical S0-S1 cross sections of the ppPs are rationalised by the nodal structure of the molecular orbitals involved in the transition. The measured electron affinities range from 380 meV (p3P) over 620 meV (p4P) to 805 meV (p5P). A saturation of the electron binding energy with the increasing number of phenyl units is thus not yet in sight.

R2022: A DFT/MRCI Ansatz with Improved Performance for Double Excitations

A reformulation of the combined density functional theory and multireference configuration interaction method (DFT/MRCI) is presented. Expressions for ab initio matrix elements are used to derive correction terms for a new effective Hamiltonian. On the example of diatomic carbon, the correction terms are derived, focusing on the doubly excited ¹Δ_g state, which was problematic in previous formulations of the method, as were double excitations in general. The derivation shows that a splitting of the parameters for intra- and interorbital interactions is necessary for a concise description of the underlying physics. Results for ¹L_a and ¹L_b states in polyacenes and ¹A_u and ¹A_g states in mini-β-carotenoids suggest that the presented formulation is superior to former effective Hamiltonians. Furthermore, statistical analysis reveals that all the benefits of the previous DFT/MRCI Hamiltonians are retained. Consequently, the here presented formulation should be considered as the new standard for DFT/MRCI calculations.

Limits to Gauge Coupling in the Dark Sector Set by the Nonobservation of Instanton-Induced Decay of Super-Heavy Dark Matter in the Pierre Auger Observatory Data

Instantons, which are nonperturbative solutions to Yang-Mills equations, provide a signal for the occurrence of quantum tunneling between distinct classes of vacua. They can give rise to decays of particles otherwise forbidden. Using data collected at the Pierre Auger Observatory, we search for signatures of such instanton-induced processes that would be suggestive of super-heavy particles decaying in the Galactic halo. These particles could have been produced during the post-inflationary epoch and match the relic abundance of dark matter inferred today. The nonobservation of the signatures searched for allows us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: α_{X}≲0.09, for 10^{9}≲M_{X}/GeV<10^{19}. Conversely, we obtain that, for instance, a reduced coupling constant α_{X}=0.09 excludes masses M_{X}≳3×10^{13}  GeV. In the context of dark matter production from gravitational interactions alone, we illustrate how these bounds are complementary to those obtained on the Hubble rate at the end of inflation from the nonobservation of tensor modes in the cosmological microwave background.

P11.15.B First multicentric real-life experience with the combination of lomustine and temozolomide in newly diagnosedMGMT promoter methylatedIDH wildtype glioblastoma

Background

The CeTeG/NOA-09 trial assessed in a randomized phase 3 setting, whether combined treatment of lomustine together with temozolomide was superior to temozolomide treatment alone in newly diagnosed MGMT (O(6)-methylguanine-DNA-methyltransferase) promoter methylated glioblastoma patients. Survival was significantly improved from 31.4 months with temozolomide alone to 48.1 months with the combination of lomustine plus temozolomide. In view of this encouraging data - suggesting this combination could have a significant impact on the survival of newly diagnosed glioblastoma patients - we were curious to assess safety and efficacy of this regimen under real-life conditions.

Material and Methods

We collected clinical and radiographic data from adult newly diagnosed MGMT promoter methylated IDH (isocitrate dehydrogenase) wildtype glioblastoma patients treated at five neuro-oncology centers in Germany. As a requirement for inclusion, first-line treatment with lomustine plus temozolomide had to be performed for at least six weeks (one course). The available radiographic data was independently reviewed by an experienced board-certified neuro-radiologist.

Results

In total, 70 patients were included. Median progression-free survival of the full cohort was 14.4 months and median overall survival was 36.0 months. Patients who received TTFields (Tumor Treating Fields) treatment for eight weeks or longer together with the combination of lomustine plus temozolomide (n=22, 31%) had a prolonged progression-free survival compared to those patients who received TTFields treatment less than eight weeks or did not receive treatment with TTFields (n=48, 69%) (21.5 months versus 11.2 months; HR: 2.118, 95% CI: 1.245-3.605; p=0.0105). In a multivariable Cox regression analysis the use of TTFields for eight weeks or longer together with the combination of lomustine plus temozolomide as well as the application of at least five courses of CeTeG therapy emerged as independent prognostic factors for progression-free survival and overall survival. Pseudoprogression occurred in n=16 (33%) of the patients. We observed no treatment related deaths and high-grade hematotoxicity in n=31 (44%) of the patients.

Conclusion

The results from this multicentric trial that investigated newly diagnosed MGMT promoter methylated IDH wildtype glioblastoma under real-life conditions indicate toxicity and survival estimates comparable to the CeTeG/NOA-09 trial. The use of TTFields for at least eight weeks in combination with this regimen was independently associated with extended progression-free and overall survival.

P11.34.A Pseudoprogression in cases of brain metastases and its neurooncological pitfalls under PD-1 inhibitor therapy in the era of personalized medicine

Background

Immunotherapy plays an increasing role in combating malignant cancers. Recently, there has been a noticeable uptick of pseudoprogression mimicking true tumor growth or even intracranial abscess. PD-1 inhibitors especially have come under scrutiny for imitating progressive diseases. Here, we summarize our departmental findings to this regard.

Material and Methods

We analyzed the clinical, intraoperative and neuropathological findings as well as perioperative radiological imaging in four cases.

Results

Four patients (three males and one female, ranged 52-74 years) underwent resection for brain metastases and were subsequently treated with radiotherapy and with PD-1 inhibitors. Within one-year post-surgery, cranial MRI-imaging showed space-occupying, contrast enhanced lesions in all four patients. In two cases FET-PETs were performed pre-operatively. They showed a significant increase in aminoacid uptake. In two cases, 5-aminolevulineacid (5-ALA) was applied pre-operatively. In one case, there was considerable 5-ALA uptake. The fourth patient presented radiological signs of an abscess and underwent emergency surgery. The neuropathological workup of all tissues in question depicted highly increased activity of lymphocytes and microglia, accompanied by necrosis. All cases were classified as pseudoprogression, which, on top, had developed supramarginally in previously healthy tissue.

Conclusion

Neurooncologists face crescent challenges in the increasing cases of pseudoprogression under/after immunotherapy. Radiological imaging doesn’t seem to be able to clearly differentiate between true and pseudoprogression. Even FET-PETs, in general a valid diagnostic tool, seem to be fooled by checkpoint inhibitors. Furthermore, pseudoprogressive tissue after PD-1 inhibitor therapy might mimic tumor tissue intra-operatively by increased 5-ALA uptake. All these characteristics increase the risk of overly aggressive resection of the suspected cancerous or infectious, but in the end pseudo-progressive tissue. Brain edema and clinical symptoms spurred by pseudoprogression may be an indication for surgery, but the risk of performing possibly unnecessary surgery based on radiological findings fooled by PD-1 inhibitors should be taken into consideration. At this point, there does not seem to be a foolproof diagnostic method to differentiate pseudo- from true progression. And there is the possibility that the pseudoprogression is happening in tissue adjacent to the previously resected lesion. Neurooncologists need to acknowledge that pseudoprogression under/after immunotherapy will become only more prevalent in the future and take this message to their patients.

P06.04.B Efficacy of Podoplanin-CAR-T Cells inex vivo Patient Derived Glioblastoma Organoids

Background

Glioblastoma (GBM) is the most prevalent malignant brain tumor in adults. Recent immunotherapeutic approaches led to promising effects both in vitro and in preclinical animal models. However, tumor heterogeneity, antigen escape mechanisms and complex interactions with the tumor microenvironment (TME) hinder their clinical breakthrough. Thus, patient derived ex vivo models are needed to test new therapeutical approaches. Genetically modified T cells expressing a chimeric antigen receptor (CAR) hold enhanced affinity for tumor associated antigens. As Podoplanin (PDPN) shows stable and increased expression in GBM, it is a suitable target antigen. When activated, CAR-T cells initiate the triad of cytokine release, T cell proliferation and target cell apoptosis. We evaluated the performance of PDPN-CAR-T cells in GBM patient derived organoids (PDO).

Material and Methods

PDOs were generated from freshly resected GBM tissue and could be cultured successfully up to several months. We assessed PDPN expression of PDOs via immunohistochemistry (IHC) prior to treatment. PDPN-CAR T cells were generated from peripheral blood mononuclear cells of healthy donors via lentiviral transduction and expansion. The transduction rate was assessed by flow cytometry prior to application. PDOs treated with untransduced T cells served as controls. PDOs were incubated with a preset number of PDPN-CAR T cells at a E:T ratio of 1:4 and were examined microscopically to register morphological disintegration after 48h. Immunofluorescence staining was conducted to detect proliferating CD4+ CART cells (CD4+/ Ki67+) after 72h and cytokine release of IFN-γ was determined via ELISA after 20h.

Results

In total, PDOs from three patients were treated with PDPN-CART cells. All of them expressed the antigen according to IHC staining. All incubated PDOs presented clear disintegration of the circular organoid shape up to total dissolving, whereas control PDOs stayed intact. CD4+ CART cells showed extensive proliferation at a mean rate of 79.8% ± 6,59% which was significant for two PDOs in comparison to control PDOs (p = 0.48, p &lt; 0.01). PDPNCART cells exhibited significantly elevated IFN-γ release in all PDOs (p &lt; 0.01).

Conclusion

We here describe PDPN as a promising target and proved effectiveness of PDPN-CAR-T cells in an ex vivo 3D model. Additional ex vivo models like tumor slice cultures might be crucial to evaluate effectiveness of CAR-T cell therapy. PDPN-CAR-T cells should be tested in these ex vivo as well as in vivo GBM models alone and in a combined approach with CARs targeting additional antigens in order to overcome tumor heterogeneity.

Primary laparoscopic fundoplication in selected patients with gastroesophageal reflux disease

BACKGROUND

Despite proton pump inhibitors being a powerful therapeutic tool, laparoscopic fundoplication (LF) has proven successful in the treatment of gastroesophageal reflux disease (GERD), through mechanical augmentation of a weak antireflux barrier and the advantages of minimally invasive access. A critical patient selection for LF, based on thorough preoperative assessment, is important for the management of GERD-patients. The purpose of this study is to provide an overview on the management of GERD-patients treated by primary LF in a specialized center and to illustrate the possible outcome after several years.

METHODS

Patients were selected after going through diagnostic workup consisting of patient's history and physical examination, upper gastrointestinal endoscopy, assessment of gastrointestinal Quality of Life Index, screening for somatoform disorders, functional assessment by esophageal manometry, (impedance)-24-hour-pH-monitoring, and selective radiographic studies. The indication for LF was based on EAES-guidelines. Either a floppy and short Nissen fundoplication was performed or a posterior Toupet-hemifundoplication was chosen. A long-term follow-up assessment was attempted after surgery.

RESULTS

In total, n = 1131 patients were evaluated (603 males; 528 females; mean age; 48.3 years; and mean body mass index: 27). The mean duration between onset of symptoms and surgery was 8 years. Nissen: n = 873, Toupet: n = 258; conversion rateerativ: 0.5%; morbidity 4%, mortality: 1 (1131). Mean follow-up (n = 898; 79%): 5.6 years; pre/post-op results: esophagitis: 66%/12.1%; Gastrointestinal Quality of Life Index: median: 92/119; daily proton pump inhibitors-intake after surgery: 8%; and operative revisions 4.3%.

CONCLUSIONS

In conclusion, our data show that careful patient selection for laparoscopic fundoplication and well-established technical concepts of mechanical sphincter augmentation can provide satisfying results in the majority of patients with severe GERD.

Development of the ion cyclotron emission diagnostic for the W7-X stellarator

An ion cyclotron emission (ICE) diagnostic is prepared for installation into the W7-X stellarator, with the aim to be operated in the 2022 experimental campaign. The design is based on the successful ICE diagnostic on the ASDEX Upgrade tokamak. The new diagnostic consists of four B-dot probes, mounted about 72° toroidally away (one module) from the neutral beam injector, with an unobstructed plasma view. Two of the B-dot probes are oriented parallel to the local magnetic field, aimed to detect fast magnetosonic waves. The remaining two probes are oriented poloidally, with the aim to detect slow waves. The radio frequency (RF) signals picked up by the probes are transferred via 50 Ω vacuum-compatible coaxial cables to RF detectors. Narrow band notch filters are used to protect the detectors from possible RF waves launched by the W7-X antenna. The signal will be sampled with a four-channel fast analog-to-digital converter with 14 bit depth and 1 GSample/s sampling rate. The diagnostic's phase-frequency characteristic is properly measured in order to allow measuring the wave vectors of the picked up waves.

[The 8th edition of the TNM staging system-a curse or a blessing for oropharyngeal carcinoma?]

At the beginning of 2017, the 8th edition of the TNM classification was presented. For oropharyngeal carcinoma, this was accompanied by a paradigm shift, as a separation of the classification depending on the association with human papillomavirus (HPV) status has been established. By considering the literature, this paper provides an overview of the characteristics of HPV-associated carcinomas, the new features of the TNM classification, and the existing points of discussion. The revision has improved the prognostic significance of the TNM classification; however, there are still tumor- and patient-dependent influencing factors that must be considered for future versions.

A42 Next-generation sequencing to analyze multiple-strain infections, genotype distribution, and antiviral resistance in hematopoietic stem cell transplantation recipients with human cytomegalovirus infection

Next-generation sequencing (NGS) produces comprehensive insights across the entire genome of the human cytomegalovirus (HCMV), which is an important opportunistic pathogen following hematopoietic stem cell transplantation (HSCT). To assess the clinical impact of HCMV diversity, genotype distribution, and resistance mutations, we performed NGS directly on plasma specimens from HSCT recipients with HCMV reactivation. Twenty-nine HCMV-positive plasma samples (median viral load 1.7 × 103 IU/ml) collected from a prospective allogenic HSCT recipient cohort (n = 16) between 21 and 80 days after transplantation were sequenced on an Illumina MiSeq after preparation of target-enriched sequencing libraries. Consensus HCMV genome sequences were assembled for 24 samples. The presence of multiple-strain infections and antiviral resistance mutations in genes UL54 and UL97 was determined by variant analysis. Genotype distribution was determined by specific marker analysis of several hypervariable genes (RL5A, RL6, RL12, RL13, UL1, UL9, UL11, UL73, UL74, UL120, UL146, and UL139). Associations between genomic and clinical features (e.g. graft-versus-host disease (GvHD), donor/recipient HCMV serostatus, dynamics of HCMV antigenemia, survival) were explored. Multiple infections involving up to 3 HCMV strains were detected in seven out of sixteen patients, with one patient analyzed at > 2 time points, showing a switch of the dominant HCMV population. No known antiviral resistance mutations were detected, which may be expected due to sample collection early after HSCT from patients without antiviral prophylaxis. Multiple-strain infection was associated with an earlier peak of HCMV-antigenemia (P = 0.054), but not with duration of viremia, antigenemia peak values, donor/recipient HCMV serostatus, T-cell depletion, acute or chronic GvHD, disease relapse, or reduced survival. Genotype distribution analysis revealed a potential link of one genotype of the immunomodulatory gene UL11 with GvHD incidence after HCMV reactivation. NGS of HCMV diversity directly from plasma samples, even with low viral loads, enables the acquisition of data of potential clinical interest. To identify reliable associations between clinical features and HCMV diversity, further patient cohorts with suitable sample sizes are required.

Poly (Butyl Acrylate)-Graft-Polystyrene Synthesis by Free-Radical Polymerization: Interplay between Structure, Morphology, Mechanical, and Optical Properties

We report a new method of preparation of poly (butyl acrylate)-g-polystyrene/polystyrene blends by free-radical polymerization. Copolymerization of glycidyl (meth)acrylate with butyl acrylate is followed by a polymer analogous reaction of this copolymer with acrylic acid and subsequent copolymerization of the modified backbone with styrene. Investigation on the number of reactive groups per backbone chain and its molecular weight allows grafting efficiencies of about 35% to be reached, as well as low cross-linking. Blends of nanophase-separated copolymers having a backbone with M_n of around 50 kg/mol and 4 reactive groups per chain are transparent, with haze as low as 14%, tensile strength of around 22 MPa, and elongations at the break of around 3%. Correlation between morphology determined by transmission electron microscopy and properties of the blend is established.

Role of hole confinement in the recombination properties of InGaN quantum structures

We study the isolated contribution of hole localization for well-known charge carrier recombination properties observed in conventional, polar InGaN quantum wells (QWs). This involves the interplay of charge carrier localization and non-radiative transitions, a non-exponential decay of the emission and a specific temperature dependence of the emission, denoted as “s-shape”. We investigate two dimensional In_0.25Ga_0.75N QWs of single monolayer (ML) thickness, stacked in a superlattice with GaN barriers of 6, 12, 25 and 50 MLs. Our results are based on scanning and high-resolution transmission electron microscopy (STEM and HR-TEM), continuous-wave (CW) and time-resolved photoluminescence (TRPL) measurements as well as density functional theory (DFT) calculations. We show that the recombination processes in our structures are not affected by polarization fields and electron localization. Nevertheless, we observe all the aforementioned recombination properties typically found in standard polar InGaN quantum wells. Via decreasing the GaN barrier width to 6 MLs and below, the localization of holes in our QWs is strongly reduced. This enhances the influence of non-radiative recombination, resulting in a decreased lifetime of the emission, a weaker spectral dependence of the decay time and a reduced s-shape of the emission peak. These findings suggest that single exponential decay observed in non-polar QWs might be related to an increasing influence of non-radiative transitions.

Modification of Dzyaloshinskii-Moriya-Interaction-Stabilized Domain Wall Chirality by Driving Currents

We measure and analyze the chirality of Dzyaloshinskii-Moriya-interaction (DMI) stabilized spin textures in multilayers of Ta|Co_{20}F_{60}B_{20}|MgO. The effective DMI is measured experimentally using domain wall motion measurements, both in the presence (using spin-orbit torques) and absence of driving currents (using magnetic fields). We observe that the current-induced domain wall motion yields a change in effective DMI magnitude and opposite domain wall chirality when compared to field-induced domain wall motion (without current). We explore this effect, which we refer to as current-induced DMI, by providing possible explanations for its emergence, and explore the possibility of its manifestation in the framework of recent theoretical predictions of DMI modifications due to spin currents.

Concurrent operation of 10 gyrotrons at W7-X experience and improvement opportunities

At the stellarator Wendelstein 7-X (W7-X) Electron Cyclotron Resonance Heating (ECRH) is the main heating system for steady-state operation and was the only available heating system during the operation phase OP1.2a in 2017. The ECRH, equipped with 10 operational 140 GHz gyrotrons [1], was used for different tasks at W7-X such as wall conditioning, controlled plasma start-up from the neutral gas up to steady state plasma control and different heating scenarios such as X2-mode and O2-mode heating as well as current drive (ECCD). The operational experiences and improvement opportunities of the ECRH plant will be discussed.

Does postexercise modelled capillary blood flow accurately reflect cardiovascular effects by different exercise intensities?

Blood flow (BF) in exercising muscles is an important factor for exercise capacity. Recently, a non-invasive method to estimate capillary BF (Q_cap ) was introduced. Using this method, the Fick principle is re-arranged by using relative differences in deoxygenated haemoglobin (ΔHHb) as a surrogate for arteriovenous O₂ difference and pulmonary oxygen uptake (VO₂ ) instead of muscular oxygen uptake. The aim of this study was to examine (I) the relationship between Q_cap and exercise intensity during and following exercise, and (II) to critically reflect the Q_cap approach. Seventeen male subjects completed six bouts of cycling exercise with different exercise intensities (40-90% peak oxygen uptake, VO_2peak ) in randomized order. VO₂ and ΔHHb were monitored continuously during the trail. Q_cap was modelled bi-exponentially, and mean response time (MRT) was calculated during recovery as well as the dissociation of modelled VO₂ and Q_cap recovery kinetics (MRT/τVO₂ ). End-exercise Q_cap increased continuously with exercise intensity. This also applied to MRT. Postexercise MRT/τVO₂ increased from 40 to 60% VO_2peak but remained stable thereafter. The results show that Q_cap response to exercise is linearly related to exercise intensity. This is presumably due to vasoactive factors like shear-stress or endothelial-mediated vasodilation. MRT/τVO₂ shows that postexercise Q_cap is elevated for a longer period than VO₂ , which is representative for metabolic demand following exercise ≥70% VO_2peak . This is a hint for prolonged local vasodilation. According to previous studies, Q_cap could not be modelled properly in some cases, which is a limitation to the method and therefore has to be interpreted with caution.

Outcome four years after transcatheter foam sclerotherapy of the greater saphenous vein

The aim of the study was to evaluate the long-term results 4 years after a single-session, sonographically guided, transcatheter foam sclerotherapy. Patients, methods: We treated 20 patients with a total of 22 legs with varicoses of the greater saphenous vein (GSV, EpAsPr). Additional varicoses of the auxiliary veins of the GSV were sclerosed immediately afterwards. 20 legs or 91% in Hach stage III-IV, clinical stage C2-C5 and a mean GSV diameter of 9 mm (range: 7 to 13 mm) could be followed up 4 years later. Results: During the follow up period one leg showed clinical signs of recurrence and underwent surgery, two legs received a single additional sclerotherapy during the four years period. Examination four years after showed in 6 legs clinical signs of recurrence without notice of clinical symptoms by the patients. This gives a clinical recurrence rate of 40% (8 of 20 patients). Duplex sonography showed flow in the region of the saphenofemoral junction in a total of 13 legs (65% of the reexamined GSVs) with an average vessel diameter of 3.7 ± 1.6mm (range 2 to 7 mm). Retreatments in 3 GSV of the 6 clinically relapsed GSV by a single injection of sclerosing foam showed an occlusion in 100% two weeks after. Conclusion: Transcatheter foam sclerotherapy of the GSV shows better clinical long-term results compared to known data of liquid sclerotherapy. Sonographically detected recurrency of the GSV could easily be retreated by a single session of foam sclerotherapy. Foam sclerotherapy is a promising and seriously to be taken option in the treatment of the insufficient GSV.

Early detection and treatment of lame cows

Objective: The aim of this study was to investigate the impact of specific hoof lesions on the locomotion score (LS) as well as the effect of early detection and treatment on duration and prevalence of lesion-specific lameness. Material and methods: In a dairy herd in Lower Saxony, Germany, with 144 lactating cows, claw trimming was performed by a professional claw trimmer at the beginning and the end of a 41-week trial period. Weekly a veterinarian assessed the LS according to Sprecher et al. (1997) in 99 cows. The front and hind claws of cows with an LS > 1 were examined and treated within 5 days. For individual diagnoses, the duration of lameness was calculated as the number of weeks from first treatment until recovery (LS = 1).Results: In total, 580 examinations and treatments were performed on 94 cows. There were 189 new lameness cases with a total of 290 diagnoses. At the first treatment, 81.0% of the cows displayed an LS of 2. Cows with digital dermatitis (DD), heel horn erosion and white line disease (WLD) more often had an LS > 2 compared to cows with Rusterholz’ sole ulcer, interdigital hyperplasia or inadequate claw length/posture (p < 0.05). Cows with only one affected leg, more often had an LS > 2 than cows with several affected legs (p < 0.1). Lameness caused by WLD and arthritis/ periarthritis remained for the longest time period. The prevalence of sole haemorrhages and/or double soles, WLD, interdigital dermatitis and interdigital hyperplasia decreased significantly during the test period. Prevalence of sole ulcer (sole ulcer and Rusterholz’ sole ulcer) and DD remained unaffected. Conclusion and clinical relevance: Locomotion score was affected by the type of claw/limb disorder and the number of diseased limbs. Regular locomotion scoring and continuous treatment of cows with an LS > 1 is associated with a decrease in the prevalence of several claw lesions. Therefore, prevalence of severe claw lesions like WLD, which was associated with a long duration of lameness, can be reduced. In con trast, for decreasing prevalence of digital dermatitis more than weekly treatment of every cow with LS > 1 is required. Preventive measures like footbaths or improved hygiene should accompany the individual animal treatment.

Changes of the bone structure after cap resurfacing arthroplasty of the humeral head

INTRODUCTION

Although humeral head resurfacing with a cap is relatively common in clinical practice, clinical studies about the changes of the bone are rare. The aim of this study was to analyse qualitative and quantitative changes of the bone after cup arthroplasty. Our hypothesis is that the implant leads to a new functional load with remarkable changes of the bone underneath the cap.

MATERIAL AND METHODS

Overall, 12 explanted caps with adherent bone tissues, retrieved at the revision surgery, were collected for histological examination. None of these implants were revised for loosening. Afterwards, there was a qualitative evaluation of the bone as well an assessment of established quantitative bone tissue parameters. Results were analyzed in correlation to the time to revision surgery, as well as to patient's age.

RESULTS

A significant decrease of the bone volume and trabecular architecture underneath the cap was already observed after a relatively short lifetime. The quantitatively measured bone loss does not depend on the patient's age, but correlates significantly with the lifetime of the implants. In contrast to these findings within the central areas, an increased bone remodeling with bone densifications and microcallus formations was noticed at the edge of the cap in most cases.

DISCUSSION

A significant reduction of the bone volume underneath the cap and remarkable changes of the trabecular architecture confirm our hypothesis. Even if these changes did not lead to a clinically relevant loosening in our series, they might influence revision surgeries. Thus, these findings might be of interest, especially when a non-stemmed reversed or anatomical revision arthroplasty with a central metaphyseal press-fit fixation is chosen.

LEVEL OF EVIDENCE

IV - retrospective or historical series.

Rational Development of Nucleoside Diphosphate Prodrugs: DiPPro-Compounds

The bio-reversible protection of nucleoside diphosphates is summarized. The design, hydrolytic characteristics, and the antiviral activity of these prodrugs of NDPs are described. In contrast to earlier attempts, the DiPPro-approach [β-(bis(acyloxybenzyl) nucleoside diphosphates)] leads to the successful delivery of the desired nucleoside diphosphates. The stability towards hydrolysis is dependent on the specific acyl moieties in the bis(acyloxybenzyl) unit as well as on the particular nucleoside analogue. Hydrolysis studies in aqueous PBS buffer (pH 7.3), 20 % human plasma in PBS, RPMI-1640 culture medium, and CEM cell extracts were carried out. Contrary to a high chemical and plasma stability, the compounds showed a very low half-life in CEM cell extracts, and efficiently released the nucleoside analogues diphosphates, e.g. of AZT, d4T and BVDU. Two additional types of cycloSal- NDP prodrugs were studied but neither proved to be useful as nucleoside diphosphate prodrugs. In summary, the results led to the development of a new series of non-symmetric nucleoside diphosphate prodrugs that selectively delivered the nucleoside diphosphate in cell extracts.

The anticipated and the lived experience of home and in-centre haemodialysis: Is there a disconnect?

This qualitative study aimed to explore home haemodialysis and in-centre haemodialysis patients’ experience, to illuminate barriers and facilitators in the uptake and maintenance of home haemodialysis. Thirty-two semi-structured interviews with patients receiving home haemodialysis or in-centre haemodialysis were analysed using framework analysis. Four themes emerged: ‘perceptions of self’; ‘impact of haemodialysis on family’; ‘perceived advantages and disadvantages of home haemodialysis and in-centre haemodialysis’ and ‘practical issues and negotiating haemodialysis’. The lived experience of home haemodialysis was in contrast to the lived experience of in-centre haemodialysis and to the anticipated experience of home haemodialysis, highlighting patient factors that contributed to under-usage of home haemodialysis.

End-exercise ΔHHb/ΔVO2 and post-exercise local oxygen availability in relation to exercise intensity

Increased local blood supply is thought to be one of the mechanisms underlying oxidative adaptations to interval training regimes. The relationship of exercise intensity with local blood supply and oxygen availability has not been sufficiently evaluated yet. The aim of this study was to examine the effect of six different intensities (40-90% peak oxygen uptake, VO_2peak ) on relative changes in oxygenated, deoxygenated and total haemoglobin (ΔO₂ Hb, ΔHHb, ΔTHb) concentration after exercise as well as end-exercise ΔHHb/ΔVO₂ as a marker for microvascular O₂ distribution. Seventeen male subjects performed an experimental protocol consisting of 3 min cycling bouts at each exercise intensity in randomized order, separated by 5 min rests. ΔO₂ Hb and ΔHHb were monitored with near-infrared spectroscopy of the vastus lateralis muscle, and VO₂ was assessed. ΔHHb/ΔVO₂ increased significantly from 40% to 60% VO₂ peak and decreased from 60% to 90% VO₂ peak. Post-exercise ΔTHb and ΔO₂ Hb showed an overshoot in relation to pre-exercise values, which was equal after 40-60% VO_2peak and rose significantly thereafter. A plateau was reached following exercise at ≥80% VO_2peak . The results suggest that there is an increasing mismatch of local O₂ delivery and utilization during exercise up to 60% VO_2peak . This insufficient local O₂ distribution is progressively improved above that intensity. Further, exercise intensities of ≥80% VO_2peak induce highest local post-exercise O₂ availability. These effects are likely due to improved microvascular perfusion by enhanced vasodilation, which could be mediated by higher lactate production and the accompanying acidosis.

[Differential Treatment Strategy of Pleural Empyema in a Post-Pneumonectomy Cavity]

INTRODUCTION

Pleural empyema in a post-pneumonectomy cavity (PEC) occurs with a frequency of 2% -15% and a mortality of more than 10%. It can occur with or without bronchopleural fistula (BPF). The treatment of empyema in the PEC requires a strict algorithm: drainage, bronchoscopy, closure of the fistula, thorough cleaning of the PEC, filling the cavity, thoracoplasty.

METHODS

39 cases with an empyema in the PEC were analysed retrospectively (men: n = 38; women: n = 1; mean age: 60.3 ± 7.6 years). In 32 (82.1%) of the patients, a BPF was detected (right: n = 26, left: n = 6). The average length of stay in hospital was 125 days (22 - 293 days). Cleaning of the PEC was achieved in all surviving patients (n = 23, 65.1%). All patients (n = 39) underwent bronchoscopy with placement of a chest tube for drainage. The BPF was closed in three cases (7.7%) with a stent while in 12 cases (30.8%) a vascularized flap was used. In 14 patients (35.9%) the bronchial stump was either reclosed with sutures or resected. In three cases (7.7%) a re-anastomosis was performed.

RESULTS

The PEC became sterile by regular flushing with antibiotic solution in three patients (7.7%). In 35.9% of the patients (n = 14), aggressive surgical debridement (Weder procedure) was necessary. A thoracic window was applied in 22 patients (56.4%), followed by negative pressure wound therapy (NPWT) and change of dressing every three to four days or a tamponade of the thoracic cavity with simple dressings. In 19 patients (48.7%) the thoracic cavity was sealed with an antibiotic solution. In 5 cases an Alexander thoracoplasty took place.

CONCLUSIONS

Pleural empyema after pneumonectomy still poses a serious postoperative complication. A bronchopleural fistula is often detected. Thus, two problems arise at the same time – fistula and infection in the pleural cavity. Through a strict algorithm, both problems can be dealt with in stages. After sealing the fistula, the thoracic cavity is thoroughly cleaned and finally the thorax is closed. Only in a small number of patients (1.3%) in whom these measures remain ineffective (persistent MRSA, aspergillus colonization) should the cavity be obliterated by thoracoplasty.

[Differential diagnosis of nasal obstruction]

Nasal obstruction can have a variety of different causes. The following text describes important diseases of the nose and paranasal sinuses, which are associated with the symptom of nasal obstruction and discusses specifics of diagnosis and therapy.

[Diagnosis and therapy of bleeding in ENT]

Bleeding in the oral cavity, nose or ear are common events in the daily routine of ENT specialists. Apart from trivial cases that often get outpatient treatment, there are numerous cases of serious bleeding that require stationary treatment and if necessary, an operative or interventional therapy. In the following section the most frequent types of bleeding, their diagnosis and therapy will be explained.

Early warning against airborne radioactivity in Bavaria: Measuring network for radioactive immissions

During the Chernobyl accident it became evident that there was no up to date information of the radiological situation in Bavaria as a whole. Therefore an online measuring network was implemented, which provides radioactivity data around the clock from all over Bavaria. It comprises measuring devices for gamma-dose rate, airborne aerosol and iodine activity and precipitation. The data are processed in accessory computers and transferred to the main network computers in Augsburg by means of a subcenter computer at the site of the IfR-station. Alarm levels are low in order to have an early warning against airborne radioactivity. New techniques for remote maintenance of the measuring devices and nuclide identification are being planned and tested.

Blocking growth by an electrically active subsurface layer: the effect of Si as an antisurfactant in the growth of GaN

Combining aberration corrected high resolution transmission electron microscopy and density functional theory calculations we propose an explanation of the antisurfactant effect of Si in GaN growth. We identify the atomic structure of a Si delta-doped layer (commonly called SiN(x) mask) as a SiGaN(3) monolayer that resembles a √3×√3 R30° surface reconstruction containing one Si atom, one Ga atom, and a Ga vacancy (V(Ga)) in its unit cell. Our density functional theory calculations show that GaN growth on top of this SiGaN(3) layer is inhibited by forming an energetically unfavorable electrical dipole moment that increases with layer thickness and that is caused by charge transfer between cation dangling bonds at the surface to V(Ga) bound at subsurface sites.