150 research outputs found

    The Innovative Performance of Alliance Block Members: Evidence from the Microelectronics Industry

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    The primary goal of this paper is to improve our understanding of the complex relationship between the positioning of companies in alliance networks and their innovative performance. In particular, we expect that a firm's innovative performance depends partly on its position in specific network settings (block membership or nonblock membership), with additional effects caused by the technology positioning strategies firms pursue in terms of technological specialization in alliance blocks. Alliance groups derive their competitive advantage from their superior and particular technologies, which they develop and exploit together in the alliance blocks. Incorporating this moderating effect of the degree of technological specialization in alliance blocks (exploitation or exploration) seems to give more insight in the contextual issues in this stream of literature.strategic technology alliances, alliance block membership strategy, microelectronics industry, innovative performance, technology strategies

    Glatiramer acetate treatment persistence - but not adherence - in multiple sclerosis patients is predicted by health-related quality of life and self-efficacy: a prospective web-based patient-centred study (CAIR study)

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    Background: In patients with relapsing remitting multiple sclerosis (RRMS) the persistence of and adherence to disease modifying drug (DMD) treatment is inadequate. To take individualised measures there is a need to identify patients with a high risk of non-persistence or non-adherence. As patient-related factors have a major influence on persistence and adherence, we investigated whether health-related quality of life (HRQoL) and self-efficacy could predict persistence or adherence. Methods: In a prospective web-based patient-centred study in 203 RRMS patients, starting treatment with glatiramer acatete (GA) 20 mg subcutaneously daily, we measured physical and mental HRQoL (Multiple Sclerosis Quality of Life54 questionnaire), functional and control self-efficacy (Multiple Sclerosis Self-Efficacy Scale), the 12-month persistence rate and, in persistent patients, the percentage of missed doses. HRQoL and self-efficacy were compared between persistent and non-persistent patients, and between adherent and non-adherent patients. Logistic regression analysis was used to assess whether persistence and adherence were explained by HRQoL and self-efficacy. Results: Persistent patients had higher baseline physical (mean 58.1 [standard deviation, SD] 16.9) and mental HRQoL (63.8 [16.8]) than non-persistent patients (49.5 [17.6]; 55.9 [20.4]) (P = 0.001; P = 0.003) with no differences between adherent and non-adherent patients (P = 0.46; P = 0.54). Likewise, in persistent patients function (752 [156]) and control self-efficacy (568 [178]) were higher than in non-persistent patients (689 [173]; 491 [192]) (P = 0.009; P = 0.004), but not in adherent vs. non-adherent patients (P = 0.26; P = 0.82). Logistic regression modelling identified physical HRQoL and control self-efficacy as factors that explained persistence. Based on predicted scores from the model, patients were classified into quartiles and the percentage of non-persistent patients per quartile was calculated: non-persistence in the highest quartile was 23.4 vs. 53.2% in the lowest quartile. Risk differentiation with respect to adherence was not possible. Based on these findings we propose a practical work-up scheme to identify patients with a high risk of nonpersistence and to identify persistence-related factors. Conclusions: Findings suggest that pre-treatment physical HRQoL and control self-efficacy may identify RRMS patients with a high risk of early discontinuation of injectable DMD treatment. Targeting of high-risk patients may enable the efficient use of persistence-promoting measures

    Differential release of histamine and prostaglandin D2 in rat peritoneal mast cells: roles of cytosolic calcium and protein tyrosine kinases

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    AbstractWe studied how the release of histamine and prostaglandin D2 (PGD2) were connected in stimulated rat peritoneal mast cells, and to what extent these processes were controlled by the cytosolic Ca2+ concentration, [Ca2+]i, and protein tyrosine kinases. In the presence of 1 mM CaCl2, the G-protein activating compound 48/80 (10 μg/ml) evoked a transient rise in [Ca2+]i and a relatively high secretion of histamine, but only a low release of PGD2. In contrast, 5 μM thapsigargin (an inhibitor of endomembrane Ca2+-ATPases) and 5 μM ionomycin evoked high and prolonged rises in [Ca2+]i, and stimulated the cells to release relatively small amounts of histamine and high amounts of PGD2. Stimulation of the cells with CaCl2 and 10 μM ATP4− gave only minor quantities of histamine and PGD2, despite of the micromolar level of [Ca+]i reached. When CaCl2 was replaced by EGTA, rises in [Ca2+]i as well as release of histamine and PGD2 were reduced with each agonist, but the preference of agonists to release more histamine or PGD2 remained unchanged. In mast cells with depleted Ca2+ stores, the addition of CaCl2 stimulated the store-regulated Ca2+ entry resulting in a prolonged rise in [Ca2+]i. However, simultaneous addition of compound 48/80 and CaCl2 was required for release of histamine and PGD2. In cells with full stores, PGD2 release evoked by compound 48/80 was greatly reduced by genistein and methyl-2,5-dihydroxycinnamate, two structurally unrelated inhibitors of protein tyrosine kinases, whereas histamine secretion was not influenced by these inhibitors. Similarly, with thapsigargin or ionomycin as agonist, PGD2 release was more sensitive to the tyrosine kinase inhibitors than histamine secretion. We conclude that in activated rat peritoneal mast cells: (i) the influx of extracellular Ca2+ potentiates agonist-evoked rises in [Ca2+]i as well as histamine secretion and PGD2 release; (ii) the amplitude of the [Ca2+]i rise does not determine the preferential effect of agonists to release more histamine or more PGD2; (iii) the relatively high PGD2 release evoked by thapsigargin and ionomycin is probably due to their potency to evoke a prolonged rise in [Ca2+]i and to activate protein tyrosine kinases

    Identification and characterization of nanobodies targeting the EphA4 receptor

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    The ephrin receptor A4 (EphA4) is one of the receptors in the ephrin system that plays a pivotal role in a variety of cell-cell interactions, mostly studied during development. In addition, EphA4 has been found to play a role in cancer biology as well as in the pathogenesis of several neurological disorders such as stroke, spinal cord injury, multiple sclerosis, amyotrophic lateral sclerosis (ALS), and Alzheimer's disease. Pharmacological blocking of EphA4 has been suggested to be a therapeutic strategy for these disorders. Therefore, the aim of our study was to generate potent and selective Nanobodies against the ligand-binding domain of the human EphA4 receptor. Weidentified two Nanobodies, Nb 39 and Nb 53, that bind EphA4 with affinities in the nanomolar range. These Nanobodies were most selective for EphA4, with residual binding to EphA7 only. Using Alphascreen technology, we found that both Nanobodies displaced all known EphA4-binding ephrins from the receptor. Furthermore, Nb39 andNb53 inhibited ephrin-induced phosphorylationoftheEphA4proteininacell-basedassay. Finally, in a cortical neuron primary culture, both Nanobodies were able to inhibit endogenous EphA4-mediated growth-cone collapse induced by ephrin-B3. Our results demonstrate the potential of Nanobodies to target the ligand-binding domain of EphA4. These Nanobodiesmaydeservefurtherevaluationaspotentialtherapeutics in disorders in which EphA4-mediated signaling plays a role

    Prediction of final infarct volume from native CT perfusion and treatment parameters using deep learning

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    CT Perfusion (CTP) imaging has gained importance in the diagnosis of acute stroke. Conventional perfusion analysis performs a deconvolution of the measurements and thresholds the perfusion parameters to determine the tissue status. We pursue a data-driven and deconvolution-free approach, where a deep neural network learns to predict the final infarct volume directly from the native CTP images and metadata such as the time parameters and treatment. This would allow clinicians to simulate various treatments and gain insight into predicted tissue status over time. We demonstrate on a multicenter dataset that our approach is able to predict the final infarct and effectively uses the metadata. An ablation study shows that using the native CTP measurements instead of the deconvolved measurements improves the prediction.Comment: Accepted for publication in Medical Image Analysi

    Increasing uniformity of biosurfactant production in Starmerella bombicola via the expression of chimeric cytochrome P450s

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    Sophorolipids are one of the best known microbial biosurfactants and are produced by several yeast species. The best studied producer is Starmerella bombicola, a non-pathogenic yeast associated in nature with bumblebees. Sophorolipids are built up of the rare disaccharide sophorose, which is attached to a fatty acid through a glyosidic bound. Sophorolipids produced by S. bombicola mainly contain oleic acid as the incorporated hydrophobic group. Other chain lengths can, to a certain content, be incorporated by feeding the yeast with substrates of alternative chain lengths. However, the efficiency for such substrates is low as compared to the preferred C18 chain length and defined by the substrate specificity of the first enzymatic step in sophorolipid biosynthesis, i.e., the cytochrome P450 enzyme CYP52M1. To increase product uniformity and diversity at the same time, a new strain of S. bombicola was developed that produces sophorolipids with a palmitic acid acyl chain. This was achieved by heterologous expression of the cytochrome P450 cyp1 gene of Ustilago maydis and feeding with palmitic acid. Optimization of the production was done by protein and process engineering

    A prospective web-based patient-centred interactive study of long-term disabilities, disabilities perception and health-related quality of life in patients with multiple sclerosis in The Netherlands:The Dutch Multiple Sclerosis Study protocol

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    BACKGROUND: In the past two decades the widespread use of disease modifying drugs with moderate to strong efficacy has changed the natural course of multiple sclerosis (MS). Health care professionals, researchers, patient organizations and health authorities are in need of recent information about the objectified and subjective long-term clinical outcomes in MS patients. Such information is scarce. METHODS/DESIGN: We started a prospective, web-based, patient-centred, interactive study of long-term disabilities, disabilities perception and health-related quality of life (HRQoL) in MS patients in The Netherlands (Dutch Multiple Sclerosis Study). The study has an on online patient-driven inclusion and online acquisition of patient-reported outcomes (PROs). At six-months intervals participants complete the Multiple Sclerosis Impact Profile (MSIP) (disabilities and disabilities perception in seven domains and four symptoms), the Multiple Sclerosis Quality of Life-54 items (MSQoL-54), the Modified Fatigue Impact Scale-5 items (MFIS-5) and the Leeds Multiple Sclerosis Quality of Life-8 items (LMSQoL) questionnaires, and a Medication and Adherence Inventory. Every three years the Expanded Disability Status Scale (EDSS) score is assessed by phone. The monthly completion of the MFIS-5, LMSQoL and Medication and Adherence Inventory is optional. Completed questionnaires and inventories, and automatically generated scores are made available online to patients for self-monitoring and self-management purposes, and to authorized health care professionals for the evaluation of disease activity and of the effectiveness of treatments. Study duration is planned to be 15 years. Results will be analyzed periodically using means and standard deviations for continuous variables, and frequencies for categorical variables. Relations between time points, variables, patient and treatment characteristics will be evaluated in random effects repeated measures models. DISCUSSION: The Dutch Multiple Sclerosis Study is characterized by online patient-driven inclusion; online data acquisition; the use of PROs; the optional monthly completion of short questionnaires; the interactive use of personal study data by patients and authorized health care professionals for self-monitoring, self-management and multidisciplinary care; the expected representativeness of the study sample; and a long-term time horizon. The study will provide valuable data on long-term disabilities, disabilities perceptions and HRQoL in MS patients in The Netherlands

    Endovascular treatment in anterior circulation stroke beyond 6.5 hours after onset or time last seen well:results from the MR CLEAN Registry

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    BACKGROUND: Randomised controlled trials with perfusion selection have shown benefit of endovascular treatment (EVT) for ischaemic stroke between 6 and 24 hours after symptom onset or time last seen well. However, outcomes after EVT in these late window patients without perfusion imaging are largely unknown. We assessed their characteristics and outcomes in routine clinical practice. METHODS: The Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands Registry, a prospective, multicentre study in the Netherlands, included patients with an anterior circulation occlusion who underwent EVT between 2014 and 2017. CT perfusion was no standard imaging modality. We used adjusted ordinal logistic regression analysis to compare patients treated within versus beyond 6.5 hours after propensity score matching on age, prestroke modified Rankin Scale (mRS), National Institutes of Health Stroke Scale, Alberta Stroke Programme Early CT Score (ASPECTS), collateral status, location of occlusion and treatment with intravenous thrombolysis. Outcomes included 3-month mRS score, functional independence (defined as mRS 0–2), and death. RESULTS: Of 3264 patients who underwent EVT, 106 (3.2%) were treated beyond 6.5 hours (median 8.5, IQR 6.9–10.6), of whom 93 (87.7%) had unknown time of stroke onset. CT perfusion was not performed in 87/106 (80.2%) late window patients. Late window patients were younger (mean 67 vs 70 years, p<0.04) and had slightly lower ASPECTS (median 8 vs 9, p<0.01), but better collateral status (collateral score 2–3: 68.3% vs 57.7%, p=0.03). No differences were observed in proportions of functional independence (43.3% vs 40.5%, p=0.57) or death (24.0% vs 28.9%, p=0.28). After matching, outcomes remained similar (adjusted common OR for 1 point improvement in mRS 1.04, 95% CI 0.56 to 1.93). CONCLUSIONS: Without the use of CT perfusion selection criteria, EVT in the 6.5–24-hour time window was not associated with poorer outcome in selected patients with favourable clinical and CT/CT angiography characteristics. randomised controlled trials with lenient inclusion criteria are needed to identify more patients who can benefit from EVT in the late window
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