Biomedical subjects

K Rossnagel

Publications and source records attributed to K Rossnagel.

16 recordsLinked to original sources

PubMed2006

[Two simple questions to diagnose post-stroke depression].

BACKGROUND AND PURPOSE: Many patients develop a depression after having suffered a stroke. Such a Post-Stroke Depression (PSD) impairs rehabilitation and quality of life. PSD is underdiagnosed in spite of available treatment. Several questionnaires have been created to diagnose a PSD. But questionnaires have been considered cumbersome and time-consuming. The aim of this study was to find out whether two simple, standardised questions will identify those stroke patients, who have developed a PSD. METHODS: The two case-finding questions and the Beck Depression Inventory (BDI) were sent to patients of the Berlin Acute Stroke Study (BASS) four years after their stroke. Incomplete questionnaires were complemented via mail or telephone. Severity of depression was assessed by means of BDI. RESULTS: Out of 211 patients, 199 responded to the questionnaire (94 %). 193 questionnaires were complete (97 %). Forty-two patients affirmed both case-finding questions (22 %). Compared to patients, who did not affirm both questions, these patients had a higher BDI score (19 +/- 8 vs. 7 +/- 5; p < 0.001). The sensitivity and specificity of the two questions were 89 % and 90 %, respectively. The positive and negative predictive value were 60 % and 98 % respectively. The number of confirmed questions (0, 1, 2) correlated well with the BDI score (r (2) = 0.67, p < 0.001). CONCLUSIONS: Two standardized questions can identify patients with PSD for further diagnostic evaluation and therapy. Diagnosis of PSD might be facilitated by using them as screening instrument.

Aged↗

PubMed2006

Emergency department delays in acute stroke - analysis of time between ED arrival and imaging.

We determined the factors leading to emergency department (ED) delays in patients with acute stroke. Data were collected prospectively in four Berlin inner-city hospitals by ED documentation, medical records, imaging files and patient interviews. An extended Cox proportional hazards model was fitted to the data. Analyses were performed in 558 patients with confirmed diagnosis of stroke. Median time from admission at ED to beginning of computed tomography/magnetic resonance imaging (CT/MRI) was 108 min. In a subgroup of patients potentially eligible for thrombolysis with a pre-hospital delay <120 min and a National Institutes of Health Stroke Scale (NIHSS) >4 (n = 74), the median interval to imaging was 68 min. Multivariable analysis revealed that a more severe initial NIHSS, a pre-hospital delay <3 h, admission at two specific hospitals, admission at weekends, and private health insurance were significantly associated with reduced delays. In stroke patients, the time interval between ED admission and imaging depends both on factors that emerge from clinical needs and on factors independent of clinical necessities. Considering the urgency of therapeutic measures in acute stroke, there is necessity and room for both improvement of in-hospital management and of medical and non-medical factors influencing pre-hospital delays.

Aged↗

PubMed2005

Continuous tuning of electronic correlations by alkali adsorption on layered 1T-TaS2.

Angle-resolved photoemission spectroscopy shows that a Mott-Hubbard type metal-insulator transition occurs at the Rb adsorbed surface of the layered charge-density-wave compound 1T-TaS2. The transition is driven by adsorption induced modifications of the charge-density wave and of the interlayer coupling, leading to an increase of the on-site Coulomb correlation energy and a narrowing of the Ta 5d band perpendicular to the layers, respectively. The continuous rearrangement of spectral weight is measured live during the deposition process.

Journal Article↗

PubMed2005

[Symptoms, risk factors, and etiology of transient ischemic attack and stroke].

BACKGROUND: It is unclear whether clinical signs and symptoms differ in the presentation of transient ischemic attack (TIA) and stroke, apart from temporal dynamics. METHODS: Signs and symptoms of patients diagnosed with TIA or stroke were prospectively collected and compared by means of an age-adjusted logistic regression analysis. Risk factors, prehospital medication, and diagnostic workup were obtained from the charts. RESULTS: Four hundred five patients diagnosed with stroke (68+/-12 years old, 45% female) and 143 diagnosed with TIA (64+/-14 years old, 48% female) were included. Signs and symptoms of patients with TIA were less often "classic" such as paresis (48% vs 71%, P<0.001) or sensory loss (38% vs 48%, P=0.03). The etiology of TIA was more often classified as "undetermined" (57% vs 46%, P<0.05). CONCLUSIONS: Transient ischemic attack needs special attention and intensive diagnostic workup, because it bears a considerable risk of death and disability but presents less often with classic signs and symptoms and its etiology often remains undetermined.

Aged↗

PubMed2005

Medical resource use and costs of health care after acute stroke in Germany.

The purpose of this study was to determine the 12 months medical resource use following admission to hospital with acute stroke and to calculate costs from a societal perspective. Data of consecutive patients with confirmed stroke were analysed. Acute hospital data were taken from medical records, socio-demographic variables from patients' interviews. A follow-up questionnaire about resource utilization was completed by patients or proxies 12 months after acute hospital admission. Costs were calculated by multiplying medical resource units used with cost factors per unit. Mean age of a total of 383 patients was 65 years and 41% were female. The median length of the initial stay in the acute hospital was 12 days at an average cost of 4650 per patient (49% of direct costs). Rehabilitation (16%), readmission (11%), medication (9%), and nursing costs (6%) were other contributors to the direct costs which amounted to a total of 9452 +/- 7599 per patient during 12 months. Indirect cost amounted to a total of 2014 +/- 5312. Patients' age, severity and type of stroke influenced the total stroke-associated costs. The large economic burden of stroke indicates the need for assessing and improving efficient health care for affected patients.

Aged↗

PubMed2004

Fermi surface and quasiparticle dynamics of Na0.7CoO2 investigated by angle-resolved photoemission spectroscopy.

We present the first angle-resolved photoemission study of Na0.7CoO2, the host material of the superconducting NaxCoO2.nH(2)O series. Our results show a hole-type Fermi surface, a strongly renormalized quasiparticle band, a small Fermi velocity, and a large Hubbard U. The quasiparticle band crosses the Fermi level from M toward Gamma suggesting a negative sign of effective single-particle hopping t(eff) (about 10 meV) which is on the order of magnetic exchange coupling J in this system. Quasiparticles are well defined only in the T-linear resistivity (non-Fermi-liquid) regime. Unusually small single-particle hopping and unconventional quasiparticle dynamics may have implications for understanding the phase of matter realized in this new class of a strongly interacting quantum system.

Journal Article↗

PubMed2004

Electronic quasiparticle renormalization on the spin wave energy scale.

High-resolution photoemission data of the (110) iron surface reveal the existence of well-defined metallic surface resonances in good correspondence to band calculations. Close to the Fermi level, their dispersion and momentum broadening display anomalies characteristic of quasiparticle renormalization due to coupling to bosonic excitations. Its energy scale exceeds that of phonons by far, and is in striking coincidence with that of the spin wave spectrum in iron. The self-energy behavior thus gives spectroscopic evidence of a quasiparticle mass enhancement due to electron-magnon coupling.

Journal Article↗

PubMed2004

Propranolol for migraine prophylaxis.

BACKGROUND: Propranolol is one of the most commonly prescribed drugs for migraine prophylaxis. OBJECTIVES: We aimed to determine whether there is evidence that propranolol is more effective than placebo and as effective as other drugs for the interval (prophylactic) treatment of patients with migraine. SEARCH STRATEGY: Potentially eligible studies were identified by searching MEDLINE/PubMed (1966 to May 2003) and the Cochrane Central Register of Controlled Trials (Issue 2, 2003), and by screening bibliographies of reviews and identified articles. SELECTION CRITERIA: We included randomised and quasi-randomised clinical trials of at least 4 weeks duration comparing clinical effects of propranolol with placebo or another drug in adult migraine sufferers. DATA COLLECTION AND ANALYSIS: Two reviewers extracted information on patients, methods, interventions, outcomes measured, and results using a pre-tested form. Study quality was assessed using two checklists (Jadad scale and Delphi list). Due to the heterogeneity of outcome measures and insufficient reporting of the data, only selective quantitative meta-analyses were performed. As far as possible, effect size estimates were calculated for single trials. In addition, results were summarised descriptively and by a vote count among the reviewers. MAIN RESULTS: A total of 58 trials with 5072 participants met the inclusion criteria. The 58 selected trials included 26 comparisons with placebo and 47 comparisons with other drugs. The methodological quality of the majority of trials was unsatisfactory. The principal shortcomings were high dropout rates and insufficient reporting and handling of this problem in the analysis. Overall, the 26 placebo-controlled trials showed clear short-term effects of propranolol over placebo. Due to the lack of studies with long-term follow up, it is unclear whether these effects are stable after stopping propranolol. The 47 comparisons with calcium antagonists, other beta-blockers, and a variety of other drugs did not yield any clear-cut differences. Sample size was, however, insufficient in most trials to establish equivalence. REVIEWERS' CONCLUSIONS: Although many trials have relevant methodological shortcomings, there is clear evidence that propranolol is more effective than placebo in the short-term interval treatment of migraine. Evidence on long-term effects is lacking. Propranolol seems to be as effective and safe as a variety of other drugs used for migraine prophylaxis.

Adrenergic beta-Antagonists↗

PubMed2004

History of the concept of 'levels of evidence' and their current status in relation to primary prevention through lifestyle interventions.

Primary prevention is a major option to reduce the burden of chronic disease in populations. Because lifestyle interventions have proved to be effective, lifestyle recommendations including nutritional advice are made abundantly. However, both their credibility and their effectiveness are often considered not to be high. Therefore, scientific evidence should form the basis of recommendations and, as in clinical medicine, a rational approach should be followed for the evaluation of evidence. In this paper, the development and current concepts of 'levels of evidence' as they are applied in clinical medicine are outlined and their impact on evidence-based recommendations is discussed. Next, the question is raised as to how far the existing schemes are applicable to the evaluation of issues pertaining to primary prevention through lifestyle changes. Current schemes were developed mainly for clinical research questions and therefore place major emphasis on randomised controlled trials as the main and most convincing evidence in the evaluation process. These types of study are rarely available for lifestyle-related factors and might even not be feasible to obtain. Arguments are advanced to support the notion that a modification of currently existing 'levels of evidence' as developed for clinical research questions might be necessary. Thereby, one might be able to accommodate the specific aspects of evidence-related issues of recommendations for primary prevention through lifestyle changes, like dietary changes.

Diet↗

PubMed2004

Regional variation and time trends in mortality from ischaemic heart disease: East and West Germany 10 years after reunification.

STUDY OBJECTIVE: Within Europe, a pronounced geographical gradient of mortality from ischaemic heart disease has been observed with the highest burden in the north east and the lowest in the south west. The study objective was to compare mortality from ischaemic heart disease between former East and West Germany since reunification. DESIGN: Analyses of age standardised mortality rates from ischaemic heart disease (ICD-9 410-414, ICD-10 I20-I25) between 1990-1991 and 2000. SETTING: Former East and West Germany. MAIN RESULTS: After a peak in the early 1990s, mortality from ischaemic heart disease has substantially declined in both parts of Germany (from 222 to 169 per 100 000 in the East and from 150 to 116 per 100 000 in the West). The regional difference, however, remained rather constant: the rate ratio between the pooled mortality in the East compared with the West was 1.51 (95% CI 1.46 to 1.56) in 1991 and 1.45 (95% CI 1.39 to 1.50) in 2000. These rate ratios were higher in women (1.63 in 1991 and 1.52 in 2000) compared with men (1.45 and 1.44, respectively). CONCLUSIONS: Within Germany, there has been a pronounced east-west gradient of mortality from ischaemic heart disease since reunification. Further insight into possible underlying reasons may lead to improved preventive strategies.

Adolescent↗

PubMed2003

Indium square root 7 x square root 3 on Si(111): a nearly free electron metal in two dimensions.

We present measurements of the Fermi surface and underlying band structure of a single layer of indium on Si(111) with square root 7 x square root 3 periodicity. Electrons from both indium valence electrons and silicon dangling bonds contribute to a nearly free, two-dimensional metal on a pseudo-4-fold lattice, which is almost completely decoupled at the Fermi level from the underlying hexagonal silicon lattice. The mean free path inferred from our data is quite long, suggesting the system might be a suitable model for studying the ground state of two-dimensional metals.

Journal Article↗

PubMed2002

Direct comparison between potential landscape and local density of states in a disordered two-dimensional electron system.

The local density of states (LDOS) of the adsorbate-induced two-dimensional electron system (2DES) on n-InAs(110) is studied by scanning tunneling spectroscopy. In contrast to a similar 3DES, the 2DES LDOS exhibits 20 times stronger corrugations and rather irregular structures. Both results are interpreted as consequences of weak localization. Fourier transforms of the LDOS reveal that the k values of the unperturbed 2DES still dominate the 2DES, but additional lower k values contribute. To clarify the origin of the LDOS patterns, we measure the potential landscape of the 2DES area. We use it to calculate the expected LDOS and find reasonable agreement between calculation and experiment.

Journal Article↗

PubMed2001

Tuning dimensionality by nanowire adsorption on layered materials.

The dimensionality of electronic states determines a number of physical phenomena such as phase transitions, transport, or superconductivity. Employing scanning tunneling microscopy combined with angle-resolved photoemission spectroscopy we demonstrate how the dimensionality of electronic states can be continuously tuned from three to two dimensions. This is achieved by adsorption of nanowires on surfaces of layered crystals without changing the chemical composition of the material. Exemplary results for Rb nanowires on TiTe2 are discussed with the help of electronic structure calculations.

Journal Article↗

PubMed2001

[Value of complementary medicine exemplified by rose-hips].

Rose-hips develop from blossoms of the wild rose (rosa canina) and are a popular natural remedy. Laboratory experiments have shown that rose-hip extract inhibits lipid oxidation in vitro and reduces the chemotaxis and chemoluminescence of leucocytes. In clinical studies serum CRP- und creatinine level declined in healthy subjects and patients with osteoarthritis under rose-hip treatment. Additionally patients suffering from osteoarthritis reported that physical symptoms declined. Data from a randomised controlled trial indicate not only that pain significantly declined but also flexion of the hip improved in the active treatment group. The anti-inflammatory properties of rose-hip are useful as a natural treatment in patients with osteoarthritis. It remains to be proven which of the components are responsible for these effects. There is some evidence that in addition to the high vitamin content flavonoids may be actively involved.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1996

Mutations affecting xanthophore pigmentation in the zebrafish, Danio rerio.

In a large-scale screen for mutants with defects in embryonic development we identified 17 genes (65 mutants) specifically required for the development of xanthophores. We provide evidence that these genes are required for three different aspects of xanthophore development. (1) Pigment cell formation and migration (pfeffer and salz); (2) pigment synthesis (edison, yobo, yocca and brie) and (3) pigment translocation (esrom, tilsit and tofu). The number of xanthophore cells that appear in the body is reduced in embryos with mutations in the two genes, salz and pfeffer. In heterozygous and homozygous salz and pfeffer adults, the melanophore stripes are interrupted, indicating that xanthophore cells have an important function in adult melanophore pattern formation. Most other genes affect only larval pigmentation. In embryos mutant for edison, yobo, yocca and brie, differences in pteridine synthesis can be observed under UV light and by thin-layer chromatography. Homozygous mutant females of yobo show a recessive maternal effect. Embryonic development is slowed down and embryos display head and tail truncations. Xanthophores in larvae mutant in the three genes esrom, tilsit and tofu appear less spread out. In addition, these mutants display a defect in retinotectal axon pathfinding. These mutations may affect xanthophore pigment distribution within the cells or xanthophore cell shape. Mutations in seven genes affecting xanthophore pigmentation remain unclassified.

Animals↗

PubMed1994

N-ethylmaleimide-sensitive fusion protein: a trimeric ATPase whose hydrolysis of ATP is required for membrane fusion.

The NEM-sensitive fusion protein, NSF, together with SNAPs (soluble NSF attachment proteins) and the SNAREs (SNAP receptors), is thought to be generally used for the fusion of transport vesicles to their target membranes. NSF is a homotrimer whose polypeptide subunits are made up of three distinct domains: an amino-terminal domain (N) and two homologous ATP-binding domains (D1 and D2). Mutants of NSF were produced in which either the order or composition of the three domains were altered. These mutants could not support intra-Golgi transport, but they indicated that the D2 domain was required for trimerization of the NSF subunits. Mutations of the first ATP-binding site that affected either the binding (K266A) or hydrolysis (E329Q) of ATP completely eliminated NSF activity. The hydrolysis mutant was an effective, reversible inhibitor of Golgi transport with an IC50 of 125 ng/50 microliters assay. Mutants in the second ATP-binding site (binding, K549A; hydrolysis, D604Q) had either 14 or 42% the specific activity of the wild-type protein, respectively. Using coexpression of an inactive mutant with wild-type subunits, it was possible to produce a recombinant form of trimeric NSF that contained a mixture of subunits. The mixed NSF trimers were inactive, even when only one mutant subunit was present, suggesting that NSF action requires each of the three subunits in a concerted mechanism. These studies demonstrate that the ability of the D1 domain to hydrolyze ATP is required for NSF activity and, therefore is required for membrane fusion. The D2 domain is required for trimerization, but its ability to hydrolyze ATP is not absolutely required for NSF function.

Adenosine Triphosphatases↗