University of Hamburg

About: University of Hamburg is a education organization based out in Hamburg, Germany. It is known for research contribution in the topics: Population & Laser. The organization has 45564 authors who have published 89286 publications receiving 2850161 citations. The organization is also known as: Hamburg University.

Neuronal KCNQ potassium channels: physiology and role in disease.

Abstract: Humans have over 70 potassium channel genes, but only some of these have been linked to disease. In this respect, the KCNQ family of potassium channels is exceptional: mutations in four out of five KCNQ genes underlie diseases including cardiac arrhythmias, deafness and epilepsy. These disorders illustrate the different physiological functions of KCNQ channels, and provide a model for the study of the 'safety margin' that separates normal from pathological levels of channel expression. In addition, several KCNQ isoforms can associate to form heteromeric channels that underlie the M-current, an important regulator of neuronal excitability.

Exploring the Sensitivity of Next Generation Gravitational Wave Detectors

Abstract: The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific potential of gravitational-wave astronomy. To support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the Universe.

Enhanced secretion of tumour necrosis factor-alpha, IL-6, and IL-1 beta by isolated lamina propria mononuclear cells from patients with ulcerative colitis and Crohn's disease.

Abstract: The perpetuation of inflammation in ulcerative colitis and Crohn's disease may be regulated in part by an increased secretion of proinflammatory cytokines due to either an appropriate response to initial stimulating agents, and/or due to an impaired down-regulation of cytokine secretion. The aim of this study was to determine the secretion patterns of the proinflammatory cytokines tumour necrosis factor-alpha (TNF-alpha), IL-6 and IL-1 beta, from isolated lamina propria mononuclear cells (LPMNC) isolated from colonic biopsies from patients with untreated ulcerative colitis or Crohn's disease. LPMNC isolated from involved inflammatory bowel disease (IBD) mucosa spontaneously produced increased amounts of TNF-alpha, and IL-6, and IL-1 beta. The TNF-alpha secretion from IBD LPMNC could be further enhanced by pokeweed mitogen stimulation. The secretion patterns of TNF-alpha and IL-1 beta by LPMNC from patients with either ulcerative colitis or Crohn's disease demonstrated a close correlation with the degree of tissue involvement and mucosal inflammation. LPMNC from non-involved ulcerative colitis mucosa secreted markedly increased levels of IL-6 compared with non-involved Crohn's disease mucosa or control mucosa. The heightened IL-6 secretion from LPMNC from non-involved ulcerative colitis mucosa without visible or microscopic signs of inflammation indicates that the pathophysiologic mechanisms involved in the initiation of inflammation may differ between ulcerative colitis and Crohn's disease. The determination of proinflammatory cytokine secretion by isolated LPMNC from colonoscopic biopsies may be a sensitive method for monitoring the severity of mucosal inflammation in IBD patients.

Neural recognition molecules of the immunoglobulin superfamily: signaling transducers of axon guidance and neuronal migration

Abstract: Recognition molecules of the immunoglobulin superfamily have important roles in neuronal interactions during ontogeny, including migration, survival, axon guidance and synaptic targeting. Their downstream signal transduction events specify whether a cell changes its place of residence or projects axons and dendrites to targets in the brain, allowing the construction of a dynamic neural network. A wealth of recent discoveries shows that cell adhesion molecules interact with attractant and repellent guidance receptors to control growth cone and cell motility in a coordinate fashion. We focus on the best-studied subclasses, the neural cell adhesion molecule NCAM and the L1 family of adhesion molecules, which share important structural and functional features. We have chosen these paradigmatic molecules and their interactions with other recognition molecules as instructive for elucidating the mechanisms by which other recognition molecules may guide cell interactions during development or modify their function as a result of injury, learning and memory.

An Exceptional Very High Energy Gamma-Ray Flare of PKS 2155-304

Abstract: The high-frequency peaked BL Lac PKS 2155-304 at redshift z=0.116 is a well-known VHE (>100 GeV) gamma-ray emitter. Since 2002 its VHE flux has been monitored using the H.E.S.S. stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia. During the July 2006 dark period, the average VHE flux was measured to be more than ten times typical values observed from the object. This article focuses solely on an extreme gamma-ray outburst detected in the early hours of July 28, 2006 (MJD 53944). The average flux observed during this outburst is I(>200 GeV) = (1.72$\pm$$0.05_{\rm stat}$$\pm$$0.34_{\rm syst}$) $\times$ 10$^{-9}$ cm$^{-2}$ s$^{-1}$, corresponding to ~7 times the flux, I(>200 GeV), observed from the Crab Nebula. Peak fluxes are measured with one-minute time scale resolution at more than twice this average value. Variability is seen up to ~600 s in the Fourier power spectrum, and well-resolved bursts varying on time scales of ~200 seconds are observed. There are no strong indications for spectral variability within the data. Assuming the emission region has a size comparable to the Schwarzschild radius of a ~10$^9 M_\odot$ black hole, Doppler factors greater than 100 are required to accommodate the observed variability time scales.