Patient-reported outcomes in large vessel vasculitis: insights from a retrospective analysis of disease activity and associated factors

BACKGROUND

Patient-reported outcomes (PROs) play a crucial role in assessing rheumatic diseases, offering insights into disease evaluation and treatment efficacy. This study focuses on PRO assessment in large vessel vasculitides, including Takayasu Arteritis and Giant Cell Arteritis (GCA).

METHODS

We retrospectively analyzed routine data from patients treated at our rheumatology clinic over a 10-year span. Patient and physician-rated global disease activity scale (G-DAS) scores, measured on a numeric rating scale (0-10 points), were collected at each visit. Clinical variables like age, sex, body mass index (BMI), disease duration, lab values, pain perception, and questionnaire responses were recorded. Linear regression and generalized additive linear regression (GAM analysis) examined associations between PROs and these factors.

RESULTS

The study included 138 patients, primarily diagnosed with GCA (94.4%). Mean follow-up was 2.5 years (0-7.7). Patient and physician G-DAS exhibited a moderate correlation (Pearson R 0.19, CI 0.14-0.24, p < 0.001). Higher patient G-DAS correlated with younger age (CI -3.4 - -1.5, p < 0.001), increased pain (CI 3.5-4, p < 0.001), functional limitations (HAQ, CI 0.5-0.6, p < 0.001), reduced physical (CI 2.3-2.7, p ≤ 0.001) and psychological well-being (CI 2.1-2.5, p < 0.001), and higher BMI (CI 1.3-2.4, p < 0.001). Physician G-DAS correlated with Birmingham Vasculitis Activity Score (V3.0; R 0.42, p 0.046) and were significantly linked to serum CRP elevations (β = 0.04, CI 0.0-0.08, p 0.028).

CONCLUSIONS

These findings underscore the need to integrate PRO measures into vasculitis disease management strategies, enhancing the understanding of disease activity from the patient's perspective.

POS1488-HPR DETERMINANTS OF PATIENT AND PHYSICIAN GLOBAL ASSESSMENT OF DISEASE ACTIVITY IN LARGE VESSEL VASCULITIS

Background

Factors influencing disease activity assessment by patients and physicians are unknown, but are highly relevant in the context of PROs development.

Objectives

To compare the patients’ and physicians’ global assessment of disease activity in large vessel vasculitis and investigate factors influencing the assessment of disease activity.

Methods

Between 2010 and 2020, patients with large vessel vasculitis and their routine caring physicians assessed a global disease activity score (numerical rating scale 0 – 10) in our outpatient clinic. We compared these global scores of disease activity. In a multiple linear regression analysis we examined the influence of potential demographical and clinical factors on the disease activity assessment.

Results

138 Patients with 866 assessments were available for analysis. At timepoint of assessment they had a mean age of 76 (± 9) years and a mean disease duration of 5 years (± 5). The median global score of patient-reported disease activity was 3 points, the median physicians’ disease activity assessment was 2 points.

In 28,2% (n=244) there was a deviation of more than 2 points between the patients’ and physicians’ assessment of disease activity. Only 5 times the physicians, but 232 times the patients rated their disease activity higher than 5 points.

In this group the patient-reported disease activity was associated with the patients age (β 0.025), the patients BMI (β 0.071) and the extent of pain (β 0.19), p<0.05. The disease duration, CRP level and the psychological well-being of the patient showed no association.

Conclusion

In our cohort, physicians and patients showed greater divergence in disease activity assessment with higher disease activity. Age, BMI and the extent of pain were associated with higher disease activity ratings by the patients. This results are relevant for the development and interpretation of PROs for activity assessment in large vessel vasculitides.

Disclosure of Interests

Anna Kernder: None declared, Marius Rohde: None declared, Hasan Acar: None declared, Oliver Sander Speakers bureau: SOBI Pharma, EUSA Pharma, AbbVie Pharma, Consultant of: SOBI Pharma, EUSA Pharma, Boehringer Pharma, Jutta Richter: None declared, Rebecca Fischer-Betz: None declared, Matthias Schneider Speakers bureau: Astra-Zeneca; Biogen; BMS; Celgene; Chugai; GSK; Janssen-Cilag; Lilly; Pfizer; UCB, Paid instructor for: Lilly, Consultant of: Abbvie; Astra-Zeneca; Boehringer-Ingelheim; GSK; Lilly; Novartis; Pfizer; Protagen; Roche; Sanofi-Aventis; UCB, Grant/research support from: Abbvie; Astra-Zeneca; GSK; UCB, Gamal Chehab: None declared

Deep brain stimulation by optimized stimulators in a phenotypic model of dystonia: Effects of different frequencies

Deep brain stimulation (DBS) of the globus pallidus internus (GPi, entopeduncular nucleus, EPN, in rodents) has become important for the treatment of generalized dystonia, a severe and often intractable movement disorder. It is unclear if lower frequencies of GPi-DBS or stimulations of the subthalamic nucleus (STN) are of advantage. In the present study, the main objective was to examined the effects of bilateral EPN-DBS at different frequencies (130 Hz, 40 Hz, 15 Hz) on the severity of dystonia in the dt^sz mutant hamster. In addition, STN stimulations were done at a frequency, proven to be effective by the present EPN-DBS in dystonic hamsters. In order to obtain precise bilateral electrical stimuli with magnitude of 50 μA, a pulse width of 60 μs and defined frequencies, it was necessary to develop a new optimized stimulator prior to the experiments. Since the individual highest severity of dystonic episodes is known to be reached within three hours after induction in dt^sz hamsters, the duration of DBS was 180 min. During DBS with 130 Hz the severity of dystonia was significantly lower within the third hour than without DBS in the same animals (p < 0.05). DBS with 40 Hz tended to exert antidystonic effects after three hours, while 15 Hz stimulations of the EPN and 130 Hz stimulations of the STN failed to show any effects on the severity. DBS of the EPN at 130 Hz was most effective against generalized dystonia in the dt^sz mutant. The response to EPN-DBS confirms that the dt^sz mutant is suitable to further investigate the effects of long-term DBS on severity of dystonia and neuronal network activities, important to give insights into the mechanisms of DBS.

Disruption of the sodium-dependent citrate transporter SLC13A5 in mice causes alterations in brain citrate levels and neuronal network excitability in the hippocampus

In addition to tissues such as liver, the plasma membrane sodium-dependent citrate transporter, NaCT (SLC13A5), is highly expressed in brain neurons, but its function is not understood. Loss-of-function mutations in the human SLC13A5 gene have been associated with severe neonatal encephalopathy and pharmacoresistant seizures. The molecular mechanisms of these neurological alterations are not clear. We performed a detailed examination of a Slc13a5 deletion mouse model including video-EEG monitoring, behavioral tests, and electrophysiologic, proteomic, and metabolomic analyses of brain and cerebrospinal fluid. The experiments revealed an increased propensity for epileptic seizures, proepileptogenic neuronal excitability changes in the hippocampus, and significant citrate alterations in the CSF and brain tissue of Slc13a5 deficient mice, which may underlie the neurological abnormalities. These data demonstrate that SLC13A5 is involved in brain citrate regulation and suggest that abnormalities in this regulation can induce seizures. The present study is the first to (i) establish the Slc13a5-knockout mouse model as a helpful tool to study the neuronal functions of NaCT and characterize the molecular mechanisms by which functional deficiency of this citrate transporter causes epilepsy and impairs neuronal function; (ii) evaluate all hypotheses that have previously been suggested on theoretical grounds to explain the neurological phenotype of SLC13A5 mutations; and (iii) indicate that alterations in brain citrate levels result in neuronal network excitability and increased seizure propensity.

Stereotactically Injected Kv1.2 and CASPR2 Antisera Cause Differential Effects on CA1 Synaptic and Cellular Excitability, but Both Enhance the Vulnerability to Pro-epileptic Conditions

PURPOSE

We present a case of voltage-gated potassium channel (VGKC) complex antibody-positive limbic encephalitis (LE) harboring autoantibodies against Kv1.2. Since the patient responded well to immunotherapy, the autoantibodies were regarded as pathogenic. We aimed to characterize the pathophysiological role of this antibody in comparison to an antibody against the VGKC-associated protein contactin-associated protein-2 (CASPR2).

METHODS

Stereotactic injection of patient sera (anti-Kv1.2-associated LE or anti-CASPR2 encephalopathy) and a control subject was performed into the hippocampus of the anesthetized rat in vivo, and hippocampal slices were prepared for electrophysiological purposes. Using extra- and intracellular techniques, synaptic transmission, long-term potentiation (LTP) and vulnerability to pro-epileptic conditions were analyzed.

RESULTS

We observed that the slope of the field excitatory postsynaptic potential (fEPSP) was significantly increased at Schaffer collateral-CA1 synapses in anti-Kv1.2-treated and anti-CASPR2-treated rats, but not at medial perforant path-dentate gyrus synapses. The increase of the fEPSP slope in CA1 was accompanied by a decrease of the paired-pulse ratio in anti-Kv1.2, but not in anti-CASPR2 tissue, indicating presynaptic site of anti-Kv1.2. In addition, anti-Kv1.2 tissue showed enhanced LTP in CA1, but dentate gyrus LTP remained unaltered. Importantly, LTP in slices from anti-CASPR2-treated animals did not differ from control values. Intracellular recordings from CA1 neurons revealed that the resting membrane potential and a single action potential were not different between anti-Kv1.2 and control tissue. However, when the depolarization was prolonged, the number of action potentials elicited was reduced in anti-Kv1.2-treated tissue compared to both control and anti-CASPR2 tissue. In contrast, polyspike discharges induced by removal of Mg2+ occurred earlier and more frequently in both patient sera compared to control.

CONCLUSION

Patient serum containing anti-Kv1.2 facilitates presynaptic transmitter release as well as postsynaptic depolarization at the Schaffer-collateral-CA1 synapse, but not in the dentate gyrus. As a consequence, both synaptic transmission and LTP in CA1 are facilitated and action potential firing is altered. In contrast, anti-CASPR2 leads to increased postsynaptic potentials, but without changing LTP or firing properties suggesting that anti-Kv1.2 and anti-CASPR2 differ in their cellular effects. Both patient sera alter susceptibility to epileptic conditions, but presumably by different mechanisms.

CK2 Inhibition Prior to Status Epilepticus Persistently Enhances KCa2 Function in CA1 Which Slows Down Disease Progression

Purpose

Epilepsy therapy is currently based on anti-seizure drugs that do not modify the course of the disease, i.e., they are not anti-epileptogenic in nature. Previously, we observed that in vivo casein kinase 2 (CK2) inhibition with 4,5,6,7-tetrabromotriazole (TBB) had anti-epileptogenic effects in the acute epilepsy slice model.

Methods

Here, we pretreated rats with TBB in vivo prior to the establishment of a pilocarpine-induced status epilepticus (SE) in order to analyze the long-term sequelae of such a preventive TBB administration.

Results

We found that TBB pretreatment delayed onset of seizures after pilocarpine and slowed down disease progression during epileptogenesis. This was accompanied with a reduced proportion of burst firing neurons in the CA1 area. Western blot analyses demonstrated that CA1 tissue from TBB-pretreated epileptic animals contained significantly less CK2 than TBB-pretreated controls. On the transcriptional level, TBB pretreatment led to differential gene expression changes of K_Ca2.2, but also of HCN1 and HCN3 channels. Thus, in the presence of the HCN channel blocker ZD7288, pretreatment with TBB rescued the afterhyperpolarizing potential (AHP) as well as spike frequency adaptation in epileptic animals, both of which are prominent functions of K_Ca2 channels.

Conclusion

These data indicate that TBB pretreatment prior to SE slows down disease progression during epileptogenesis involving increased K_Ca2 function, probably due to a persistently decreased CK2 protein expression.

Distinct Effects of Stereotactically Injected Human Cerebrospinal Fluid Containing Glutamic Acid Decarboxylase Antibodies into the Hippocampus of Rats on the Development of Spontaneous Epileptic Activity

Background: The conversion of glutamic acid into γ-aminobutyric acid (GABA) is catalyzed by the glutamic acid decarboxylase (GAD). Antibodies against this enzyme have been described in neurological disorders, but the pathophysiological role of these antibodies is still poorly understood. We hypothesized that anti-GAD autoantibodies could diminish the GABA content in the slice and facilitate epileptic activity. Methods: Cerebrospinal fluids (CSF) from two patients containing anti-GAD (A and B) were injected into the rat hippocampus in vivo. Hippocampal slices were prepared for electrophysiological field potential recordings in order to record recurrent epileptic discharges (REDs) in the CA1 region induced by the removal of Mg2+ and/or by adding gabazine. As control groups, we injected an anti-GAD-negative human CSF or saline solution, and we used non-operated naive animals. Results: RED frequencies were significantly higher in the Mg2+-free solution than in the gabazine-containing solution. The average frequency of REDs in the last 10 min and the average duration of REDs in the last 5 min did not show significant differences between the anti-GAD-B-treated and the control slices, but in the Mg2+-free solution, anti-GAD-A had significantly higher epileptic activity than anti-GAD-B. Conclusions: These results indicate that anti-GAD has distinct effects on the development of spontaneous epileptic activity.

Human Osteoblast Migration in DC Electrical Fields Depends on Store Operated Ca2+-Release and Is Correlated to Upregulation of Stretch-Activated TRPM7 Channels

Fracture healing and bone regeneration, particularly in the elderly, remains a challenge. There is an ongoing search for methods to activate osteoblasts, and the application of electrical fields is an attractive approach in this context. Although it is known that such electromagnetic fields lead to osteoblast migration and foster mesenchymal osteogenic differentiation, so far the mechanisms of osteoblast activation remain unclear. Possible mechanisms could rely on changes in Ca²⁺-influx via ion channels, as these are known to modulate osteoblast activity, e.g., via voltage-sensitive, stretch-sensitive, transient-receptor-potential (TRP) channels, or store-operated release. In the present in vitro study, we explored whether electrical fields are able to modulate the expression of voltage-sensitive calcium channels as well as TRP channels in primary human osteoblast cell lines. We show migration speed is significantly increased in stimulated osteoblasts (6.4 ± 2.1 μm/h stimulated, 3.6 ± 1.1 μm/h control), and directed toward the anode. However, within a range of 154–445 V/m, field strength did not correlate with migration velocity. Neither was there a correlation between electric field and voltage-gated calcium channel (Ca_v3.2 and Ca_v1.4) expression. However, the expression of TRPM7 significantly correlated positively to electric field strength. TRPM7 channel blockade using NS8593, in turn, did not significantly alter migration speed, nor did blockade of Ca_v3.2 and Ca_v1.4 channels using Ni⁺ or verapamil, respectively, while a general Ca²⁺-influx block using Mg²⁺ accelerated migration. Stimulating store-operated Ca²⁺-release significantly reduced migration speed, while blocking IP3 had only a minor effect (at low and high concentrations of 2-APB, respectively). We conclude that (i) store operated channels negatively modulate migration speed and that (ii) the upregulation of TRPM7 might constitute a compensatory mechanism-which might explain how increasing expression levels at increasing field strengths result in constant migration speeds.

The German Aerospace Center M-42 radiation detector-A new development for applications in mixed radiation fields

In the last few years, the Biophysics Working Group of the Institute of Aerospace Medicine of the German Aerospace Center (DLR) started the development of a small low power consumption radiation detector system for the measurement of the absorbed dose to be applied in various environments, such as onboard aircraft, in space, and also as a demonstration tool for students. These so called DLR M-42 detectors are based on an electronics design, which can easily be adjusted to the user- and mission-requirements. M-42 systems were already applied for measurements in airplanes, during two MAPHEUS (Materialphysikalische Experimente unter Schwerelosigkeit) rocket missions, and are currently prepared for long term balloon experiments. In addition, they will be part of the dosimetry suite of the upcoming Matroshka AstroRad Radiation Experiment on the NASA Artemis I mission. This paper gives an overview of the design and the testing of the DLR M-42 systems and provides highlighted results from the MAPHEUS campaigns where the detectors were tested for the first time under space flight conditions. Results clearly show that the system design enables independent measurements starting upon rocket launch due to the built-in accelerometer sensors and provides data for the relevant 6 min of μ-gravity as given for the MAPHEUS missions. These 6 min of the μ-gravity environment at altitudes between 100 and 240 km lead to a total absorbed dose of 1.21 ± 0.15 µGy being equivalent to half a day of radiation background measured with the M-42 in the laboratory at DLR, Cologne, Germany.

Planctopirus ephydatiae, a novel Planctomycete isolated from a freshwater sponge

The microbiome of freshwater sponges is rarely studied, and not a single novel bacterial species has been isolated and subsequently characterized from a freshwater sponge to date. A previous study showed that 14.4% of the microbiome from Ephydatia fluviatilis belong to the phylum Planctomycetes. Therefore, we sampled an Ephydatia sponge from a freshwater lake and employed enrichment techniques targeting bacteria from the phylum Planctomycetes. The obtained strain spb1^T was subject to genomic and phenomic characterization and found to represent a novel planctomycetal species proposed as Planctopirus ephydatiae sp. nov. (DSM 106606 = CECT 9866). In the process of differentiating spb1^T from its next relative Planctopirus limnophila DSM 3776^T, we identified and characterized the first phage - Planctopirus phage vB_PlimS_J1 - infecting planctomycetes that was only mentioned anecdotally before. Interestingly, classical chemotaxonomic methods would have failed to distinguish Planctopirus ephydatiae strain spb1^T from Planctopirus limnophila DSM 3776^T. Our findings demonstrate and underpin the need for whole genome-based taxonomy to detect and differentiate planctomycetal species.

Bidirectional shift of group III metabotropic glutamate receptor-mediated synaptic depression in the epileptic hippocampus

A common function of group III metabotropic glutamate receptors (mGluRs) located at the presynaptic site of a glutamatergic synapse is synaptic depression. Here, we studied synaptic depression mediated by group III mGluR activation at Schaffer collateral-CA1 (SC-CA1) synapses and associational-commissural-CA3 (AC-CA3) synapses by recording field excitatory postsynaptic potentials in the in vitro brain slice preparation. In order to gauge the impact of synaptic depression in chronically epileptic tissue, we compared rats after pilocarpine-induced status epilepticus (post-SE) with control animals. We observed that synaptic transmission at control AC-CA3 synapses was sensitive to the group III mGluR agonist L-AP4 (10μM), while there was no effect of this compound at SC-CA1 synapses in the same tissue. In contrast, synaptic depression at AC-CA3 synapses by L-AP4 was lost in chronically epileptic tissue, and we found a significant synaptic depression at SC-CA1 synapses in post-SE tissue by L-AP4 and by the mGluR8-selective agonist DCPG. The depression by L-AP4 and DCPG in CA1 was also demonstrated in immature control tissue suggesting developmental down-regulation of mGluR8 at this synapse as well as re-appearance of this isoform under pathological conditions. Quantitative real-time RT-PCR was used to identify mGluR isoforms and to assess their transcriptional changes in post-SE tissue. These analyses revealed down-regulation of mGluR4 and mGluR6 at AC-CA3 and up-regulation of mGluR8 at SC-CA1 synapses. We conclude that group III mGluR-mediated synaptic depression is differentially altered in chronically epileptic tissue by a bidirectional shift of the transcriptional level.

Gingival esthetics and oral health-related quality of life in patients with cleft lip and palate

While the oral health-related quality of life (OHRQoL) is known to be reduced in patients with cleft lip and palate (CLP), its inter-dependency with the soft tissue characteristics of the CLP area remains unclear. This study aimed to evaluate the soft tissue characteristics in the treated cleft area in order to investigate whether gingival esthetics correlate with OHRQoL. Thirty-six patients with unilateral or bilateral CLP (46 cleft areas) were investigated after secondary/tertiary alveolar bone grafting and orthodontic/prosthetic implant treatment using an adapted score to rate gingival esthetics (clinical esthetic score, CES). The patient's OHRQoL was determined using the German short version of the Oral Health Impact Profile questionnaire (OHIP-G14). The results showed a significantly better rating in patients with their own teeth in situ (12.05±1.10) than in patients with implants (6.95±4.78) or prosthetics (4.00±3.58). The best OHRQoL values were achieved by patients with their own teeth integrated into the cleft area (1.32±2.31), followed by patients with implants (2.33±2.33) and prosthetics (3.75±5.87). A significant (P=0.017) correlation was found between OHIP-G14 and CES scores, suggesting an increased OHRQoL in cases with higher oral esthetics in the cleft area. The therapeutic strategy contributes to both gingival esthetics and OHRQoL. The patient's subjective perception of OHRQoL can be attributed to objective gingival esthetic ratings.

Measurement of reaction kinetics of [177Lu]Lu-DOTA-TATE using a microfluidic system

Design and evaluation of a microfluidic system that allowed the determination of Arrhenius parameters for the formation of [¹⁷⁷Lu]Lu-DOTA-TATE using clinical radiolabeling conditions.

Anti-GAD65 Containing Cerebrospinal Fluid Does not Alter GABAergic Transmission

Glutamic acid decarboxylase of 65 kDa (GAD65) antibodies have been reported in a variety of neurological disorders such as stiff-person syndrome (SPS), sporadic ataxia and some cases of epilepsy. Since the target is believed to be the cytoplasmic enzyme GAD65, the key enzyme of γ-aminobutyric acid (GABA) synthesis, the pathophysiological role of these antibodies is poorly understood. Here, we stereotactically injected human cerebrospinal fluid (CSF) containing GAD65-antibodies into the hippocampus of rats in vivo and then prepared hippocampal slices 1-2 days after post-operative recovery. We characterized both evoked and spontaneous GABAergic transmission in vitro using sharp microelectrode and patch-clamp recordings in CA1 neurons. Intracellular recordings with sharp microelectrodes from CA1 neurons showed that evoked GABAAR- or GABABR-mediated inhibitory postsynaptic potentials (IPSP) remained unaltered in anti-GAD65 tissue. These results were confirmed with patch-clamp recordings showing no difference in evoked gabazine-sensitive inhibitory postsynaptic currents (IPSCs). In addition, spontaneous IPSCs also showed no difference between anti-GAD65 tissue and controls with respect to the mean frequency, the mean amplitude and the sIPSC distribution. In conclusion, stereotactic injection of GAD65-antibodies into the hippocampus leaves evoked and spontaneous GABAergic synaptic transmission intact. Hence, dysfunction of the inhibitory GABAergic system does not appear to be the major mechanism of epileptogenicity in this disease.

[Speech Ability and Psychological Outcome After Treatment of Oral Cancer]

BACKGROUND

In recent years interactions between surgical treatment of oral carcinoma and incidence of anxiety or depression have become a subject of discussions. This prospective study is a comparison between the extent of loss of speech intelligibility and presence of depressive symptoms or anxiety as a result of oral carcinoma.

MATERIAL AND METHODS

One year after surgical therapy for oral carcinoma, 90 patients of an average age of 60±12 years were examined. Their speech intelligibility degree was measured using standardized automatic speech recognition (word recognition rate, WR). Symptoms of anxiety and depression were detected by use of HAD-Scales (HADS). Next to the relationship between WR and HADS other influential variables related to WR and HADS were statistically evaluated.

RESULTS

The WR average was 53.2±17.2. Female WR was better than male. The difference between tumor classifications T1 and T4 compared to the WR reached statistical significance. Significant differences were detected between WR and "tumor localization", "graft donor site", "graft morphology", "tongue motility", and "tracheostoma" groups. There was a relationship between tongue motility and graft morphology, graft donor site and tumor localization. HAD-Scores in the mean were elevated: HADS-Total=43.3%, HADS-A=43.3% und HADS-D= 51.1%. WR correlates with HADS-D-Subscale, but not with HADS-A-Subscale.

CONCLUSION

Communication disorders as a result of neoplasmic orofacial surgery may be related to extent of the treatment and to affective impairments. This should receive attention in the concept of rehabilitation.

A Blind, Numerical Benchmark Study on Supercritical Water Heat Transfer Experiments in a 7-Rod Bundle

Heat transfer in supercritical water reactors (SCWRs) shows a complex behavior, especially when the temperatures of the water are near the pseudocritical value. For example, a significant deterioration of heat transfer may occur, resulting in unacceptably high cladding temperatures. The underlying physics and thermodynamics behind this behavior are not well understood yet. To assist the worldwide development in SCWRs, it is therefore of paramount importance to assess the limits and capabilities of currently available models, despite the fact that most of these models were not meant to describe supercritical heat transfer (SCHT). For this reason, the Gen-IV International Forum initiated the present blind, numerical benchmark, primarily aiming to show the predictive ability of currently available models when applied to a real-life application with flow conditions that resemble those of an SCWR. This paper describes the outcomes of ten independent numerical investigations and their comparison with wall temperatures measured at different positions in a 7-rod bundle with spacer grids in a supercritical water test facility at JAEA. The wall temperatures were not known beforehand to guarantee the blindness of the study. A number of models have been used, ranging from a one-dimensional (1-D) analytical approach with heat transfer correlations to a RANS simulation with the SST turbulence model on a mesh consisting of 62 million cells. None of the numerical simulations accurately predicted the wall temperature for the test case in which deterioration of heat transfer occurred. Furthermore, the predictive capabilities of the subchannel analysis were found to be comparable to those of more laborious approaches. It has been concluded that predictions of SCHT in rod bundles with the help of currently available numerical tools and models should be treated with caution.

Stereotactic injection of cerebrospinal fluid from anti-NMDA receptor encephalitis into rat dentate gyrus impairs NMDA receptor function

Autoimmune encephalitis is increasingly recognized in patients with otherwise unexplained encephalopathy with epilepsy. Among these, patients with anti-N-methyl D-aspartate receptor (NMDAR) encephalitis present epileptic seizures, memory deficits, and psychiatric symptoms. However, the functional consequences of such autoantibodies are poorly understood. In order to investigate the pathophysiology of this disease, we stereotactically injected either cerebrospinal fluid (CSF) from three anti-NMDAR encephalitis patients or commercially available anti-NMDAR1 into the dentate gyrus of adult female rats. Control animals were injected with either CSF obtained from three epilepsy patients (ganglioglioma, posttraumatic epilepsy, focal cortical dysplasia) lacking anti-NMDAR or saline. Intracellular recordings from dentate gyrus granule cells showed a significant reduction of the NMDAR-evoked excitatory postsynaptic potentials (NMDAR-EPSPs) in animals treated with anti-NMDAR. As a consequence of this, action potential firing in these cells by NMDAR-EPSPs was significantly impaired. Long-term potentiation in the dentate gyrus was also significantly reduced in rats injected with anti-NMDAR as compared to control animals. This was accompanied by a significantly impaired learning performance in the Morris water maze hidden platform task when the animals had been injected with anti-NMDAR antibody-containing CSF. Our findings suggest that anti-NMDAR lead to reduced NMDAR function in vivo which could contribute to the memory impairment found in patients with anti-NMDAR encephalitis.

Murine solid tumours as a novel model to study bacterial biofilm formation in vivo

Bacteria of many species are able to invade and colonize solid tumours in mice. We have focused on Salmonella enterica serovar Typhimurium. Detailed analysis revealed that such tumour-invading Salmonella form biofilms, thus providing a versatile in vivo test system for studying bacterial phenotypes and host-pathogen interactions. It appears that biofilm formation by S. typhimurium is induced as a defence against the immune system of the host, and in particular against neutrophils. Further, we extended our work to the clinically more relevant biofilm infection by Pseudomonas aeruginosa. The induction of P. aeruginosa biofilms in neoplastic tissue appears to be elicited as a reaction against the immune system. Reconstitution experiments reveal that T cells are responsible for biofilm induction. Isogenic mutants that are no longer able to form biofilms can be used for comparison studies to determine antimicrobial resistance, especially therapeutic efficacy against P. aeruginosa located in biofilms.

Pneumococcal phosphoglycerate kinase interacts with plasminogen and its tissue activator

Streptococcus pneumoniae is not only a commensal of the nasopharyngeal epithelium, but may also cause life-threatening diseases. Immune-electron microscopy studies revealed that the bacterial glycolytic enzyme, phosphoglycerate kinase (PGK), is localised on the pneumococcal surface of both capsulated and non-capsulated strains and colocalises with plasminogen. Since pneumococci may concentrate host plasminogen (PLG) together with its activators on the bacterial cell surface to facilitate the formation of plasmin, the involvement of PGK in this process was studied. Specific binding of human or murine PLG to strain-independent PGK was documented, and surface plasmon resonance analyses indicated a high affinity interaction with the kringle domains 1-4 of PLG. Crystal structure determination of pneumococcal PGK together with peptide array analysis revealed localisation of PLG-binding site in the N-terminal region and provided structural motifs for the interaction with PLG. Based on structural analysis data, a potential interaction of PGK with tissue plasminogen activator (tPA) was proposed and experimentally confirmed by binding studies, plasmin activity assays and thrombus degradation analyses.

Influence of Processing Parameters on the Fiber Length and Impact Properties of Injection Molded Long Glass Fiber Reinforced Polypropylene

Injection molding of long fiber-reinforced thermoplastics is a well-established method in automotive industry to produce high quality structural parts in mass production without the need of further finishing, where the performance is strongly dependent on the fiber length. It is known that the processing parameters have to be carefully chosen as they directly influence the final fiber length and can therefore have a negative effect on the resulting mechanical properties of the part. Particularly in terms of impact behavior, the fiber length is seen as a key factor. The aim of the present work is to quantify the effects of the injection molding parameters on the impact behavior of long fiber reinforced compounds. In a first step the resulting fiber length of injection molded glass fiber reinforced polypropylene is analyzed as a function of the injection velocity, holding pressure, revolution speed and back pressure. The single steps of fiber length analysis are carefully investigated in terms of feasibility and accuracy, in order to assure that a reproducible and reliable test method is employed. Subsequently, the impact behavior of the PP-GF compounds is quantified by falling dart experiments, and the results are then correlated to the fiber length and the processing parameters to establish a fundamental processing-structure-property relationship. The investigation of the fiber length analysis shows that a high pyrolysis temperature leads to embrittlement of the glass fibers and a decrease of tensile strength of the single fibers. This may consequently lead to incorrect characterization of the fiber length due to fiber breakage. The results of the statistical investigation of the processing parameters indicate a significant influence of the back pressure on both impact energy and fiber length.

Micro Replication by Injection-Compression Molding

The replication of polymeric microstructures on a flat surface is not easily achieved by conventional injection molding, because of the required micro-dimensional control and the stringent tolerances of most applications. Moreover, the flow behaviour of melts in micro cavities remains not well understood and challenging. On the other hand, injection-compression molding is an established process for the manufacturing of optical storage media, like compact discs (CD) or digital versatile discs (DVD), with grooves and pits at the micro-scale. The difficulties arise mainly from two sources: lack of adequate filling because of premature freezing of features with very small thicknesses and excessive deformation during ejection due to high friction at the polymer-metal interface. In this work, a study is carried out to investigate the effect of process parameters on the replication of various microstructures on a flat disk using microinjection-compression molding. A commercial microinjection molding machine has been used in the study. Two optical grade polymers poly(methyl methacrylate) (PMMA) and cyclic olefin polymer (COP) were used in conjunction with various mold inserts to reproduce the embedded microstructures. The dimensions of the microstructures on the inserts and molded parts were measured with a confocal profiler. A transcription ratio was defined to assess the quality of the replication. The design of experiment (DOE) method was used to obtain correlations between the process parameters and the development of the microstructure during injection-compression molding.

Identification and characterization of the arginine deiminase system of Streptococcus canis

Although Streptococcus (S.) canis is known to cause severe infections in dogs and cats and harbors a clear zoonotic potential, knowledge about physiology and pathogenesis is mostly elusive. The arginine deiminase system (ADS) has been described in certain streptococcal species and its role in the establishment of infection has been suggested. In this study we focused on the identification and characterization of the ADS in S. canis. Using genome sequencing and subsequent in silico analysis we identified the ADS of S. canis as a gene cluster composed of seven genes. RT-PCR analysis revealed that the ADS of S. canis is transcribed in four transcriptional units, comprising three monocistronical mRNAs and one operon structure. As a secondary metabolic pathway, the ADS of S. canis is strictly regulated by carbon catabolite repression (CCR) and arginine as demonstrated on transcriptional, translational, and enzymatical level, respectively. Furthermore, growth kinetics with a chemically defined medium clearly showed that arginine, the substrate of the ADS, is essential for the biological fitness of S. canis. Using Immuno-electron microscopy analysis, we observed a surface-exposed localization of the ADS enzymes arginine deiminase (ArcA), ornithine carbamoyltransferase (ArcB), and carbamate kinase (ArcC), respectively, which might suggest the contribution of the ADS to the development of streptococcal infections.