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1.
PLoS One ; 19(5): e0304610, 2024.
Article in English | MEDLINE | ID: mdl-38820451

ABSTRACT

Face Morphing Attacks pose a threat to the security of identity documents, especially with respect to a subsequent access control process, because they allow both involved individuals to use the same document. Several algorithms are currently being developed to detect Morphing Attacks, often requiring large data sets of morphed face images for training. In the present study, face embeddings are used for two different purposes: first, to pre-select images for the subsequent large-scale generation of Morphing Attacks, and second, to detect potential Morphing Attacks. Previous studies have demonstrated the power of embeddings in both use cases. However, we aim to build on these studies by adding the more powerful MagFace model to both use cases, and by performing comprehensive analyses of the role of embeddings in pre-selection and attack detection in terms of the vulnerability of face recognition systems and attack detection algorithms. In particular, we use recent developments to assess the attack potential, but also investigate the influence of morphing algorithms. For the first objective, an algorithm is developed that pairs individuals based on the similarity of their face embeddings. Different state-of-the-art face recognition systems are used to extract embeddings in order to pre-select the face images and different morphing algorithms are used to fuse the face images. The attack potential of the differently generated morphed face images will be quantified to compare the usability of the embeddings for automatically generating a large number of successful Morphing Attacks. For the second objective, we compare the performance of the embeddings of two state-of-the-art face recognition systems with respect to their ability to detect morphed face images. Our results demonstrate that ArcFace and MagFace provide valuable face embeddings for image pre-selection. Various open-source and commercial-off-the-shelf face recognition systems are vulnerable to the generated Morphing Attacks, and their vulnerability increases when image pre-selection is based on embeddings compared to random pairing. In particular, landmark-based closed-source morphing algorithms generate attacks that pose a high risk to any tested face recognition system. Remarkably, more accurate face recognition systems show a higher vulnerability to Morphing Attacks. Among the systems tested, commercial-off-the-shelf systems were the most vulnerable to Morphing Attacks. In addition, MagFace embeddings stand out as a robust alternative for detecting morphed face images compared to the previously used ArcFace embeddings. The results endorse the benefits of face embeddings for more effective image pre-selection for face morphing and for more accurate detection of morphed face images, as demonstrated by extensive analysis of various designed attacks. The MagFace model is a powerful alternative to the often-used ArcFace model in detecting attacks and can increase performance depending on the use case. It also highlights the usability of embeddings to generate large-scale morphed face databases for various purposes, such as training Morphing Attack Detection algorithms as a countermeasure against attacks.


Subject(s)
Algorithms , Computer Security , Humans , Face , Image Processing, Computer-Assisted/methods , Automated Facial Recognition/methods , Facial Recognition
2.
IEEE Trans Pattern Anal Mach Intell ; 46(7): 4957-4976, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38319772

ABSTRACT

Deep neural networks have become prevalent in human analysis, boosting the performance of applications, such as biometric recognition, action recognition, as well as person re-identification. However, the performance of such networks scales with the available training data. In human analysis, the demand for large-scale datasets poses a severe challenge, as data collection is tedious, time-expensive, costly and must comply with data protection laws. Current research investigates the generation of synthetic data as an efficient and privacy-ensuring alternative to collecting real data in the field. This survey introduces the basic definitions and methodologies, essential when generating and employing synthetic data for human analysis. We summarise current state-of-the-art methods and the main benefits of using synthetic data. We also provide an overview of publicly available synthetic datasets and generation models. Finally, we discuss limitations, as well as open research problems in this field. This survey is intended for researchers and practitioners in the field of human analysis.


Subject(s)
Databases, Factual , Humans , Neural Networks, Computer , Biometric Identification/methods , Algorithms , Deep Learning , Pattern Recognition, Automated/methods
3.
Sensors (Basel) ; 22(21)2022 Oct 27.
Article in English | MEDLINE | ID: mdl-36365934

ABSTRACT

Despite the long history of fingerprint biometrics and its use to authenticate individuals, there are still some unsolved challenges with fingerprint acquisition and presentation attack detection (PAD). Currently available commercial fingerprint capture devices struggle with non-ideal skin conditions, including soft skin in infants. They are also susceptible to presentation attacks, which limits their applicability in unsupervised scenarios such as border control. Optical coherence tomography (OCT) could be a promising solution to these problems. In this work, we propose a digital signal processing chain for segmenting two complementary fingerprints from the same OCT fingertip scan: One fingerprint is captured as usual from the epidermis ("outer fingerprint"), whereas the other is taken from inside the skin, at the junction between the epidermis and the underlying dermis ("inner fingerprint"). The resulting 3D fingerprints are then converted to a conventional 2D grayscale representation from which minutiae points can be extracted using existing methods. Our approach is device-independent and has been proven to work with two different time domain OCT scanners. Using efficient GPGPU computing, it took less than a second to process an entire gigabyte of OCT data. To validate the results, we captured OCT fingerprints of 130 individual fingers and compared them with conventional 2D fingerprints of the same fingers. We found that both the outer and inner OCT fingerprints were backward compatible with conventional 2D fingerprints, with the inner fingerprint generally being less damaged and, therefore, more reliable.


Subject(s)
Dermatoglyphics , Skin , Humans , Skin/diagnostic imaging , Biometry/methods , Tomography, Optical Coherence/methods , Fingers/diagnostic imaging , Fingers/anatomy & histology
4.
Sensors (Basel) ; 22(3)2022 Jan 20.
Article in English | MEDLINE | ID: mdl-35161540

ABSTRACT

This work presents an automated contactless fingerprint recognition system for smartphones. We provide a comprehensive description of the entire recognition pipeline and discuss important requirements for a fully automated capturing system. In addition, our implementation is made publicly available for research purposes. During a database acquisition, a total number of 1360 contactless and contact-based samples of 29 subjects are captured in two different environmental situations. Experiments on the acquired database show a comparable performance of our contactless scheme and the contact-based baseline scheme under constrained environmental influences. A comparative usability study on both capturing device types indicates that the majority of subjects prefer the contactless capturing method. Based on our experimental results, we analyze the impact of the current COVID-19 pandemic on fingerprint recognition systems. Finally, implementation aspects of contactless fingerprint recognition are summarized.


Subject(s)
COVID-19 , Pandemics , Algorithms , Databases, Factual , Humans , SARS-CoV-2
5.
IEEE Trans Image Process ; 30: 8251-8264, 2021.
Article in English | MEDLINE | ID: mdl-34559651

ABSTRACT

The deep learning models for the Single Image Super-Resolution (SISR) task have found success in recent years. However, one of the prime limitations of existing deep learning-based SISR approaches is that they need supervised training. Specifically, the Low-Resolution (LR) images are obtained through known degradation (for instance, bicubic downsampling) from the High-Resolution (HR) images to provide supervised data as an LR-HR pair. Such training results in a domain shift of learnt models when real-world data is provided with multiple degradation factors not present in the training set. To address this challenge, we propose an unsupervised approach for the SISR task using Generative Adversarial Network (GAN), which we refer to hereafter as DUS-GAN. The novel design of the proposed method accomplishes the SR task without degradation estimation of real-world LR data. In addition, a new human perception-based quality assessment loss, i.e., Mean Opinion Score (MOS), has also been introduced to boost the perceptual quality of SR results. The pertinence of the proposed method is validated with numerous experiments on different reference-based (i.e., NTIRE Real-world SR Challenge validation dataset) and no-reference based (i.e., NTIRE Real-world SR Challenge Track-1 and Track-2) testing datasets. The experimental analysis demonstrates committed improvement from the proposed method over the other state-of-the-art unsupervised SR approaches, both in terms of subjective and quantitative evaluations on different reference metrics (i.e., LPIPS, PI-RMSE graph) and no-reference quality measures such as NIQE, BRISQUE and PIQE. We also provide the implementation of the proposed approach (https://github.com/kalpeshjp89/DUSGAN) to support reproducible research.

6.
Sensors (Basel) ; 21(17)2021 Aug 24.
Article in English | MEDLINE | ID: mdl-34502576

ABSTRACT

Within the last few decades, the need for subject authentication has grown steadily, and biometric recognition technology has been established as a reliable alternative to passwords and tokens, offering automatic decisions. However, as unsupervised processes, biometric systems are vulnerable to presentation attacks targeting the capture devices, where presentation attack instruments (PAI) instead of bona fide characteristics are presented. Due to the capture devices being exposed to the public, any person could potentially execute such attacks. In this work, a fingerprint capture device based on thin film transistor (TFT) technology has been modified to additionally acquire the impedances of the presented fingers. Since the conductance of human skin differs from artificial PAIs, those impedance values were used to train a presentation attack detection (PAD) algorithm. Based on a dataset comprising 42 different PAI species, the results showed remarkable performance in detecting most attack presentations with an APCER = 2.89% in a user-friendly scenario specified by a BPCER = 0.2%. However, additional experiments utilising unknown attacks revealed a weakness towards particular PAI species.


Subject(s)
Biometric Identification , Algorithms , Biometry , Electric Impedance , Fingers , Humans
7.
Sensors (Basel) ; 19(12)2019 Jun 14.
Article in English | MEDLINE | ID: mdl-31207911

ABSTRACT

The term "plenoptic" comes from the Latin words plenus ("full") + optic. The plenoptic function is the 7-dimensional function representing the intensity of the light observed from every position and direction in 3-dimensional space. Thanks to the plenoptic function it is thus possible to define the direction of every ray in the light-field vector function. Imaging systems are rapidly evolving with the emergence of light-field-capturing devices. Consequently, existing image-processing techniques need to be revisited to match the richer information provided. This article explores the use of light fields for face analysis. This field of research is very recent but already includes several works reporting promising results. Such works deal with the main steps of face analysis and include but are not limited to: face recognition; face presentation attack detection; facial soft-biometrics classification; and facial landmark detection. This article aims to review the state of the art on light fields for face analysis, identifying future challenges and possible applications.


Subject(s)
Face/anatomy & histology , Facial Recognition , Image Processing, Computer-Assisted/methods , Pattern Recognition, Automated/methods , Algorithms , Biometry/methods , Humans
8.
Eur J Cell Biol ; 94(7-9): 391-400, 2015.
Article in English | MEDLINE | ID: mdl-26116074

ABSTRACT

Ca(2+)-activated K(+) channels (KCa) play a pivotal role in the endothelium-dependent hyperpolarization and regulation of vascular tone and blood pressure. For activation, KCa depend on an increase of intracellular calcium which is substantially mediated by Ca(2+)-permeable cation channels including the transient receptor potential V4 (TRPV4). It has been proposed that KCa and Ca(2+)-permeable cation channels may be clustered in localized positions within the cell membrane to form functional units and that caveolae may constitute the scaffolding for such microcompartmental organization. Here, we sought to elucidate the composition and functional relevance of these microcompartments in vitro and in vivo. We show that TRPV4 and small-conductance KCa2.3 are enriched in caveolae of human microvascular endothelial cells. Using immunoprecipitation, immunocytology and superresolution microscopy, we found a caveolae-dependent association between caveolin-1, TRPV4 and small conductance KCa2.3, but not intermediate conductance KCa3.1, in endothelial cells under static condition. Mechanical stimulation of cells via exposure to shear stress led to a partial de-novo colocalization of KCa3.1 with Cav-1 and TRPV4. In a mouse model of genetic Cav-1 deficiency, we found significantly reduced KCa-mediated currents as determined by patch-clamping in carotid artery endothelial cells (CAEC) from Cav-1(-/-) mice compared to wildtype. Functionally, Cav-1 deficiency was associated with impaired endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilation in response to shear stress and acetylcholine. In summary, our findings provide evidence for a dynamic microcompartmentation of TRPV4/KCa in caveolae of endothelial cells and highlight the importance of Cav-1 for endothelial KCa functions and flow-induced vasodilation.


Subject(s)
Caveolae/physiology , Caveolin 1/metabolism , Endothelial Cells/physiology , Small-Conductance Calcium-Activated Potassium Channels/metabolism , TRPV Cation Channels/metabolism , Animals , Calcium/metabolism , Caveolin 1/genetics , Cell Compartmentation , Humans , Intermediate-Conductance Calcium-Activated Potassium Channels/metabolism , Mice , Mice, Knockout , Patch-Clamp Techniques , Vasodilation/physiology
9.
IEEE Trans Image Process ; 24(3): 1060-75, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25622320

ABSTRACT

The vulnerability of face recognition systems isa growing concern that has drawn the interest from both academic and research communities. Despite the availability of a broad range of face presentation attack detection (PAD)(or countermeasure or antispoofing) schemes, there exists no superior PAD technique due to evolution of sophisticated presentation attacks (or spoof attacks). In this paper, we present a new perspective for face presentation attack detection by introducing light field camera (LFC). Since the use of a LFC can record the direction of each incoming ray in addition to the intensity, it exhibits an unique characteristic of rendering multiple depth(or focus) images in a single capture. Thus, we present a novel approach that involves exploring the variation of the focus between multiple depth (or focus) images rendered by the LFC that in turn can be used to reveal the presentation attacks. To this extent, we first collect a new face artefact database using LFC that comprises of 80 subjects. Face artefacts are generated by simulating two widely used attacks, such as photo print and electronic screen attack. Extensive experiments carried out on the light field face artefact database have revealed the outstanding performance of the proposed PAD scheme when benchmarked with various well established state-of-the-art schemes.


Subject(s)
Biometric Identification/methods , Face/anatomy & histology , Image Processing, Computer-Assisted/methods , Algorithms , Databases, Factual , Humans , Lighting
11.
Sensors (Basel) ; 12(5): 5246-72, 2012.
Article in English | MEDLINE | ID: mdl-22778583

ABSTRACT

In a biometric authentication system using protected templates, a pseudonymous identifier is the part of a protected template that can be directly compared. Each compared pair of pseudonymous identifiers results in a decision testing whether both identifiers are derived from the same biometric characteristic. Compared to an unprotected system, most existing biometric template protection methods cause to a certain extent degradation in biometric performance. Fusion is therefore a promising way to enhance the biometric performance in template-protected biometric systems. Compared to feature level fusion and score level fusion, decision level fusion has not only the least fusion complexity, but also the maximum interoperability across different biometric features, template protection and recognition algorithms, templates formats, and comparison score rules. However, performance improvement via decision level fusion is not obvious. It is influenced by both the dependency and the performance gap among the conducted tests for fusion. We investigate in this paper several fusion scenarios (multi-sample, multi-instance, multi-sensor, multi-algorithm, and their combinations) on the binary decision level, and evaluate their biometric performance and fusion efficiency on a multi-sensor fingerprint database with 71,994 samples.


Subject(s)
Biometry , Algorithms , Decision Support Techniques
12.
Proc Natl Acad Sci U S A ; 106(34): 14518-23, 2009 Aug 25.
Article in English | MEDLINE | ID: mdl-19706538

ABSTRACT

Proliferation of interstitial fibroblasts is a hallmark of progressive renal fibrosis commonly resulting in chronic kidney failure. The intermediate-conductance Ca(2+)-activated K(+) channel (K(Ca)3.1) has been proposed to promote mitogenesis in several cell types and contribute to disease states characterized by excessive proliferation. Here, we hypothesized that K(Ca)3.1 activity is pivotal for renal fibroblast proliferation and that deficiency or pharmacological blockade of K(Ca)3.1 suppresses development of renal fibrosis. We found that mitogenic stimulation up-regulated K(Ca)3.1 in murine renal fibroblasts via a MEK-dependent mechanism and that selective blockade of K(Ca)3.1 functions potently inhibited fibroblast proliferation by G(0)/G(1) arrest. Renal fibrosis induced by unilateral ureteral obstruction (UUO) in mice was paralleled by a robust up-regulation of K(Ca)3.1 in affected kidneys. Mice lacking K(Ca)3.1 (K(Ca)3.1(-/-)) showed a significant reduction in fibrotic marker expression, chronic tubulointerstitial damage, collagen deposition and alphaSMA(+) cells in kidneys after UUO, whereas functional renal parenchyma was better preserved. Pharmacological treatment with the selective K(Ca)3.1 blocker TRAM-34 similarly attenuated progression of UUO-induced renal fibrosis in wild-type mice and rats. In conclusion, our data demonstrate that K(Ca)3.1 is involved in renal fibroblast proliferation and fibrogenesis and suggest that K(Ca)3.1 may represent a therapeutic target for the treatment of fibrotic kidney disease.


Subject(s)
Fibroblasts/drug effects , Intermediate-Conductance Calcium-Activated Potassium Channels/antagonists & inhibitors , Kidney/drug effects , Pyrazoles/pharmacology , Animals , Apoptosis/drug effects , Blotting, Western , Cell Cycle/drug effects , Cell Line , Cell Proliferation/drug effects , Fibroblast Growth Factor 2/pharmacology , Fibroblasts/cytology , Fibroblasts/physiology , Fibrosis/etiology , Fibrosis/prevention & control , Flow Cytometry , Gene Expression/drug effects , Intermediate-Conductance Calcium-Activated Potassium Channels/genetics , Intermediate-Conductance Calcium-Activated Potassium Channels/physiology , Kidney/metabolism , Kidney/pathology , Membrane Potentials/drug effects , Mice , Mice, Knockout , Patch-Clamp Techniques , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Ureteral Obstruction/complications
13.
Circulation ; 119(17): 2323-32, 2009 May 05.
Article in English | MEDLINE | ID: mdl-19380617

ABSTRACT

BACKGROUND: It has been proposed that activation of endothelial SK3 (K(Ca)2.3) and IK1 (K(Ca)3.1) K+ channels plays a role in the arteriolar dilation attributed to an endothelium-derived hyperpolarizing factor (EDHF). However, our understanding of the precise function of SK3 and IK1 in the EDHF dilator response and in blood pressure control remains incomplete. To clarify the roles of SK3 and IK1 channels in the EDHF dilator response and their contribution to blood pressure control in vivo, we generated mice deficient for both channels. METHODS AND RESULTS: Expression and function of endothelial SK3 and IK1 in IK1(-/-)/SK3(T/T) mice was characterized by patch-clamp, membrane potential measurements, pressure myography, and intravital microscopy. Blood pressure was measured in conscious mice by telemetry. Combined IK1/SK3 deficiency in IK1(-/-)/SK3(T/T) (+doxycycline) mice abolished endothelial K(Ca) currents and impaired acetylcholine-induced smooth muscle hyperpolarization and EDHF-mediated dilation in conduit arteries and in resistance arterioles in vivo. IK1 deficiency had a severe impact on acetylcholine-induced EDHF-mediated vasodilation, whereas SK3 deficiency impaired NO-mediated dilation to acetylcholine and to shear stress stimulation. As a consequence, SK3/IK1-deficient mice exhibited an elevated arterial blood pressure, which was most prominent during physical activity. Overexpression of SK3 in IK1(-/-)/SK3(T/T) mice partially restored EDHF- and nitric oxide-mediated vasodilation and lowered elevated blood pressure. The IK1-opener SKA-31 enhanced EDHF-mediated vasodilation and lowered blood pressure in SK3-deficient IK1(+/+)/SK3(T/T) (+doxycycline) mice to normotensive levels. CONCLUSIONS: Our study demonstrates that endothelial SK3 and IK1 channels have distinct stimulus-dependent functions, are major players in the EDHF pathway, and significantly contribute to arterial blood pressure regulation. Endothelial K(Ca) channels may represent novel therapeutic targets for the treatment of hypertension.


Subject(s)
Biological Factors/physiology , Hypertension/etiology , Vasodilation , Animals , Biological Factors/metabolism , Blood Pressure/physiology , Calcium/metabolism , Membrane Potentials , Mice , Mice, Knockout , Muscle, Smooth, Vascular/physiopathology , Myocytes, Smooth Muscle/physiology , Shaw Potassium Channels/deficiency , Small-Conductance Calcium-Activated Potassium Channels/deficiency
14.
Surgery ; 145(4): 392-8, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19303987

ABSTRACT

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disease with a tremendous impact on the quality of life. Controversies over which patients should be operated on because they may benefit most from thymectomy are still ongoing. The aim of this study was to report our long-term results of patients with MG with comparison of thymectomy and conservative treatment. METHODS: We report a series of 252 patients with MG. Survival data were generated. Patients were seen in the outpatient clinic, where a modified Osserman score and quality of life score were evaluated at the end of the follow-up period for all surviving patients. RESULTS: A total of 172 patients with MG were followed after thymectomy or with conservative treatment for a median time of 9.8 years. Patients who underwent thymectomy had significantly greater rates of remission and improvement compared with conservative treatment. Furthermore, they had a significantly greater survival. CONCLUSION: Currently, different effective modalities of treatment are available in patients with MG. In our long-term follow-up, thymectomy was superior to conservative treatment regarding overall survival, clinical improvement, and remission rate. Therefore, thymectomy should be considered strongly for all patients with generalized MG.


Subject(s)
Myasthenia Gravis/surgery , Quality of Life , Thymectomy , Adolescent , Adult , Aged , Aged, 80 and over , Child , Female , Germany/epidemiology , Humans , Male , Middle Aged , Myasthenia Gravis/diagnosis , Myasthenia Gravis/mortality , Treatment Outcome , Young Adult
15.
Mol Pharmacol ; 75(2): 281-95, 2009 Feb.
Article in English | MEDLINE | ID: mdl-18955585

ABSTRACT

Small-conductance (KCa2.1-2.3) and intermediate-conductance (KCa3.1) calcium-activated K(+) channels are critically involved in modulating calcium-signaling cascades and membrane potential in both excitable and nonexcitable cells. Activators of these channels constitute useful pharmacological tools and potential new drugs for the treatment of ataxia, epilepsy, and hypertension. Here, we used the neuroprotectant riluzole as a template for the design of KCa2/3 channel activators that are potent enough for in vivo studies. Of a library of 41 benzothiazoles, we identified 2 compounds, anthra[2,1-d]thiazol-2-ylamine (SKA-20) and naphtho[1,2-d]thiazol-2-ylamine (SKA-31), which are 10 to 20 times more potent than riluzole and activate KCa2.1 with EC(50) values of 430 nM and 2.9 microM, KCa2.2 with an EC(50) value of 1.9 microM, KCa2.3 with EC(50) values of 1.2 and 2.9 microM, and KCa3.1 with EC(50) values of 115 and 260 nM. Likewise, SKA-20 and SKA-31 activated native KCa2.3 and KCa3.1 channels in murine endothelial cells, and the more "drug-like" SKA-31 (half-life of 12 h) potentiated endothelium-derived hyperpolarizing factor-mediated dilations of carotid arteries from KCa3.1(+/+) mice but not from KCa3.1(-/-) mice. Administration of 10 and 30 mg/kg SKA-31 lowered mean arterial blood pressure by 4 and 6 mm Hg in normotensive mice and by 12 mm Hg in angiotensin-II-induced hypertension. These effects were absent in KCa3.1-deficient mice. In conclusion, with SKA-31, we have designed a new pharmacological tool to define the functional role of the KCa2/3 channel activation in vivo. The blood pressure-lowering effect of SKA-31 suggests KCa3.1 channel activation as a new therapeutic principle for the treatment of hypertension.


Subject(s)
Benzothiazoles/pharmacology , Biological Factors/metabolism , Blood Pressure/drug effects , Endothelium/drug effects , Intermediate-Conductance Calcium-Activated Potassium Channels/metabolism , Animals , Mice , Potassium Channels/metabolism
16.
Pflugers Arch ; 458(2): 291-302, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19037656

ABSTRACT

Gardos channel, the erythrocyte Ca(2+)-activated K(+) channel (K(Ca)3.1), is considered a major regulator of red blood cell (RBC) volume by mediating efflux of potassium and thus cell dehydration and shrinkage. However, the functional importance of K(Ca)3.1 in RBC in vivo is incompletely understood. Here, we used K(Ca)3.1(-/-)-mice to investigate the consequences of K(Ca)3.1 deficiency for RBC indices, functions, and sequestration. RBCs of K(Ca)3.1(-/-)-mice of all ages were mildly macrocytic but their biconcave appearance being preserved. RBC number, total hemoglobin, and hematocrit were unchanged in the adult K(Ca)3.1(-/-)-mice and increased in the premature K(Ca)3.1(-/-)-mice. Filterability, Ca(2+)-dependent volume decrease and osmotic tolerance of RBCs lacking K(Ca)3.1 were noticeably reduced when compared to RBC of wild-type littermates. Deformability to increasing shear stress was unchanged. Strikingly, K(Ca)3.1(-/-)-mice developed progressive splenomegaly which was considerable ( approximately 200% of controls) in the >6-month-old mice and was paralleled by increased iron deposition in the aged mice presumably as a consequence of enhanced RBC sequestration. Daily injections of the K(Ca)3.1-blocker TRAM-34 (120 mg/kg) also produced mild splenomegaly in wild-type mice. We conclude that genetic deficit of erythroid K(Ca)3.1 causes mild RBC macrocytosis, presumably leading to reduced filterability, and impairs volume regulation. These RBC defects result in mild but progressive splenomegaly.


Subject(s)
Erythrocyte Deformability/drug effects , Intermediate-Conductance Calcium-Activated Potassium Channels/physiology , Splenomegaly/etiology , Animals , Cell Death/drug effects , Cell Size , Erythrocyte Count , Erythrocyte Indices/drug effects , Erythrocytes , Flow Cytometry , Intermediate-Conductance Calcium-Activated Potassium Channels/deficiency , Iron/metabolism , Mice , Pyrazoles/pharmacology
18.
Stud Health Technol Inform ; 136: 673-8, 2008.
Article in English | MEDLINE | ID: mdl-18487809

ABSTRACT

Setting up networks among physicians and other health professionals in virtually any medical discipline is an important part of establishing eHealth world-wide. Medical research strategies nowadays advance diagnostic and therapeutic knowledge and guidelines allowing patients to benefits. Patient data and samples are among the most sensitive information and must carefully be protected according to rules of ethics and professional discretion as well as national and international privacy legislation. A lot has been said about "patient involvement, patient empowerment". What about health professionals? How can they be involved and empowered to address the paradigm shift towards a personalized health service provision? Information and communication technology (ICT), medical devices, and software applications are not among the topics health professionals typically deal with while being theoretically and practically trained to diagnose diseases and treat patients. An ICT-based training and information provision is required to update the ICT skills of health professionals. The German CAST association provides such an information platform where health professionals attend applied computer security education events. This article aims at describing how ICT and security education is provided to health professionals, and how these training courses are designed, structured, performed, and assessed.


Subject(s)
Awareness , Computer Communication Networks , Computer Security , Inservice Training , Medical Records Systems, Computerized , Medical Staff, Hospital/education , Nursing Staff, Hospital/education , Curriculum , Germany , Humans
19.
Cardiovasc Res ; 79(1): 80-8, 2008 Jul 01.
Article in English | MEDLINE | ID: mdl-18339646

ABSTRACT

AIMS: Potassium channels are essential elements of endothelial function. Recently, evidence emerged that the TWIK (tandem of P domains in a weak inwardly rectifying K+ channel)-related K+ channel (TREK-1) of the two-pore domain potassium channel gene family (K2P) may be involved in the regulation of vascular tone. However, the functional and molecular characterization of vascular TREK-1 is incomplete. In this study, we therefore analysed the functional expression of TREK-1 in the endothelium. Moreover, we hypothesized that changes in channel expression may contribute to altered endothelial vasodilator response under conditions of elevated blood pressure. METHODS AND RESULTS: Gene expression and function of endothelial TREK-1 were analysed by single-cell RT-PCR, the patch-clamp technique and pressure myography in murine carotid arteries (CA). K+ outward currents displaying the characteristics of TREK-1 were observed following various TREK-1-activating stimuli such as membrane stretch, intracellular acidosis, polyunsaturated fatty acids, isoflurane (ISOFL), riluzole, and acetylcholine (ACh). In K(Ca)3.1(-/-) mice exhibiting elevated blood pressure, endothelial TREK-1 currents and TREK-1 mRNA expression were enhanced as compared with normotensive control mice. TREK-1-mediated vasodilator responses to alpha-linolenic acid, ISOFL, or ACh were increased. A similar up-regulation of endothelial TREK-1 was observed in spontaneously hypertensive rats. CONCLUSION: We have found that TREK-1 is an endothelial K+ channel capable of producing hyperpolarization and vasodilation. A correlation between hypertension and up-regulation of TREK-1 was observed in two different animal models of elevated blood pressure. Thus, TREK-1 may play a protective role in the cardiovascular system by providing a novel type of endothelial hyperpolarization-mediated vasodilator response.


Subject(s)
Carotid Arteries/metabolism , Endothelium, Vascular/metabolism , Hypertension/metabolism , Potassium Channels, Tandem Pore Domain/metabolism , Animals , Blood Pressure/physiology , Carotid Arteries/cytology , Carotid Arteries/pathology , Disease Models, Animal , Endothelium, Vascular/cytology , Endothelium, Vascular/pathology , Hypertension/pathology , Hypertension/physiopathology , Male , Mice , Mice, Knockout , Patch-Clamp Techniques , Potassium Channels, Tandem Pore Domain/genetics , Protein Structure, Tertiary/genetics , Rats , Rats, Inbred SHR , Rats, Inbred WKY , Up-Regulation/physiology , Vasodilation/physiology
20.
Surg Endosc ; 22(11): 2470-7, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18297352

ABSTRACT

BACKGROUND: Myasthenia gravis is an autoimmune disease with a great impact on quality of life. Besides conservative treatment with mestinon and immunosuppressive medication, thymectomy is an established intervention that offers substantial improvements of the disease. Since the past decade, minimally invasive procedures have been performed. This study aimed to report on the long-term results for all the patients who underwent thymectomy for myasthenia gravis, paying special attention to postoperative disease-related outcome, quality of life, and differences regarding the operative approach. METHODS: This report describes a series of 131 patients with generalized myasthenia gravis who underwent thymectomy between 1980 and 2005. The clinical course data during the hospitalization and consultation in our outpatient clinic were reviewed, and survival data were generated. The patients were seen in the outpatient clinic, where a modified Osserman and quality-of-life score was evaluated at the end of the follow-up period for all surviving patients. RESULTS: A total of 106 patients with myasthenia gravis were followed up after thymectomy for a median time of 8 years (range, 1-27 years). Eight patients died during this period. The perioperative mortality rate was 0%, and the morbidity rate was 19.8%. The patients with thymoma and a high preoperative Osserman score had a significantly shorter survival. With minimally invasive procedures, the hospital stay was significantly shorter, and the rate for improvement of myasthenia gravis-associated symptoms was significantly higher. The rate of perioperative complications and myasthenia-related complications during the follow-up period showed no significant differences. CONCLUSIONS: Transsternal and minimally invasive thymectomy contribute to an improvement in myasthenia gravis symptoms for all subgroups. Surgery can be performed with low individual risks. In our trial, minimally invasive surgery was found to be superior in terms of improvement in myasthenia gravis-associated symptoms. Additionally, the hospital stay was shorter, and the patients felt less disturbed by direct effects of the operation. Therefore, minimally invasive thymectomy can be regarded as the treatment of choice for patients undergoing surgery for myasthenia gravis.


Subject(s)
Myasthenia Gravis/surgery , Quality of Life , Thoracoscopy/methods , Thymectomy/methods , Adolescent , Adult , Aged , Aged, 80 and over , Chi-Square Distribution , Child , Female , Humans , Longitudinal Studies , Male , Middle Aged , Prognosis , Proportional Hazards Models , Statistics, Nonparametric , Treatment Outcome
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