Event dependent overall survival in the population-based LIFE-Adult-Study.

BACKROUND: Information about the direct comparability of big data of epidemiological cohort studies and the general population still is lacking, especially regarding all-cause mortality rates. The aim of this study was to investigate the overall survival and the influence of several diagnoses in the medical history on survival time, adjusted to common risk factors in a populations-based cohort. METHODS: From 10,000 subjects of the population-based cohort LIFE-Adult-Study (Leipzig Research Centre for Civilization Diseases), the medical history and typical risk factors such as age, smoking status and body-mass-index (BMI) were assessed. The survival status was identified from the saxonian population register. Univariate and multivariate analyses were used to determine the influence of the medical history and risk factors on overall survival. To develope an optimal model, the method by Collet [1] was used. RESULTS: The mortality rate of the participants is approximately half the mortality rate expected for the german population. The selection bias in epidemiological studies needs to be considered whenever interpreting results of epidemiological cohort studies. Nevertheless we have shown that several diagnoses proved to have a negative influence on overall survival time even in this relatively healthy cohort. This study showed the significantly increased mortality risk if the following diseases are reported in medical history of the participants in a large population-based cohort study including adults aged 18 and over: diabetes mellitus (HR 1.533, p = 0.002), hypertension (HR 1.447, p = 0.005), liver cirrhosis (HR 4.251, p < 0.001), osteoporosis (HR 2.165, p = 0.011), chronic bronchitis (HR 2.179, p < 0.001), peptic ulcer disease (HR 1.531, p = 0.024) and cancer (HR 1.797, p < 0.001). Surprisingly, asthma has the opposite effect on survival time (HR 0.574, p = 0.024), but we believe this may be due to an overrepresentation of mild to moderate asthma and its management, which includes educating patients about a healthy lifestyle. CONCLUSION: In the LIFE-Adult-Study, common risk factors and several diseases had relevant effect on overall survival. However, selection bias in epidemiological studies needs to be considered whenever interpreting results of epidemiological cohort studies. Nevertheless it was shown that the general cause-and-effect principles also apply in this relatively healthy cohort.

The human Müller cell line MIO-M1 expresses opsins.

PURPOSE: To determine whether the human Müller cell line Moorfields/Institute of Ophthalmology-Müller 1 (MIO-M1) expresses opsins. METHODS: The gene expression of opsins was determined by reverse-transcription PCR (RT-PCR). The presence of opsin proteins was determined by western blotting and immunocytochemistry. The light sensitivity of the cells was examined with imaging experiments using the calcium-sensitive dye Fluo-4. RESULTS: MIO-M1 cells express glial (glutamine synthase [GLUL], vimentin [VIM], glial fibrillary acidic protein [GFAP], cellular retinaldehyde-binding protein [RLBP1], glial high-affinity glutamate transporter [SLCA1], aquaporin-4 [AQP4], inwardly rectifying potassium channel Kir4.1 [Kir4.1]), neuronal (Thy-1 cell surface antigen [THY1], heavy neurofilament polypeptide [NEFH], microtubule-associated protein 2 [MAP2], neurogenic differentiation 1 [NEUROD1], neuronal nuclei [NEUN]), and neural progenitor markers (Nestin [NES], paired-type homeobox transcription factor [PAX6], neurogenic locus notch homolog 1 [NOTCH1]). The cells contain mRNA for the following opsins: blue opsin (OPN1SW), rhodopsin (OPN2), panopsin (OPN3), melanopsin (OPN4), neuropsin (OPN5), and peropsin (RRH), as well as for the transducins (guanine nucleotide binding protein [GNAZ], alpha transducing activity polypeptide 1 [GNAT1], alpha transducing activity polypeptide 2 [GNAT2]). The presence of blue opsin and melanopsin was confirmed with immunocytochemistry and western blotting. The immunoreactivity and mRNA of red-green opsin were found in some but not all cultures, while the immunoreactivity for rhodopsin was absent in all cultures investigated. Repetitive stimulation with 480 nm light evoked slow and fast transient calcium responses in the majority of cells investigated, while irradiation with 600 nm light was ineffective. CONCLUSIONS: The human Müller cell line MIO-M1 expresses opsins. This suggests immortalized Müller cells could be used as a cellular source to produce human opsins for their potential application as therapeutic agents in patients with retinitis pigmentosa.

Neurite branch retraction is caused by a threshold-dependent mechanical impact.

Recent results indicate that, in addition to chemical cues, mechanical stimuli may also impact neuronal growth. For instance, unlike most other cell types, neurons prefer soft substrates. However, the mechanisms responsible for the neuronal affinity for soft substrates have not yet been identified. In this study, we show that, in vitro, neurons continuously probe their mechanical environment. Growth cones visibly deform substrates with a compliance commensurate with their own. To understand the sensing of stiff substrates by growth cones, we investigated their precise temporal response to well-defined mechanical stress. When the applied stress exceeded a threshold of 274 +/- 41 pN/microm(2), neurons retracted and re-extended their processes, thereby enabling exploration of alternative directions. A calcium influx through stretch-activated ion channels and the detachment of adhesion sites were prerequisites for this retraction. Our data illustrate how growing neurons may detect and avoid stiff substrates--as a mechanism involved in axonal branch pruning--and provide what we believe is novel support of the idea that mechanics may act as guidance cue for neuronal growth.

Light stimulation evokes two different calcium responses in Müller glial cells of the guinea pig retina.

Intracellular calcium responses are a characteristic of glial activation upon neuronal activity. In acutely isolated preparations of the guinea pig retina, Müller glial cells displayed cytosolic calcium rises in response to repetitive light stimulation. The calcium rises consisted of two components, a slowly developing immediate response that occurred simultaneously over the whole length of all Müller cell fibers and a delayed fast response that originated in the ganglion cell layer and spread as a wave through the bodies of some Müller cells toward the outer processes in the photoreceptor layer. The slow calcium response was evoked by photoreceptor-to-glia signaling, resulting in a glutamate transporter- and zinc-mediated alteration in the membrane potential and an influx of calcium from the extracellular space. The fast calcium response was evoked by a release of calcium from intracellular stores, probably after activation of purinergic receptors. The data suggest that light stimulation of the retina causes glial activation by alterations in both the membrane potential and receptor-mediated mechanisms. The former may be implicated in glial support of the neuronal signal transfer from photoreceptors to ganglion cells (glial forward signaling), whereas the latter may constitute a glial feedback signaling from ganglion cells to photoreceptors.

Glutamate-evoked alterations of glial and neuronal cell morphology in the guinea pig retina.

Neuronal activity is accompanied by transmembranous ion fluxes that cause cell volume changes. In whole mounts of the guinea pig retina, application of glutamate resulted in fast swelling of neuronal cell bodies in the ganglion cell layer (GCL) and the inner nuclear layer (INL) (by approximately 40%) and a concomitant decrease of the thickness of glial cell processes in the inner plexiform layer (IPL) (by approximately 40%) that was accompanied by an elongation of the glial cells, by a thickening of the whole retinal tissue, and by a shrinkage of the extracellular space (by approximately 18%). The half-maximal effect of glutamate was observed at approximately 250 mum, after approximately 4 min. The swelling was caused predominantly by AMPA-kainate receptor-mediated influx of Na+ into retinal neurons. Similar but transient morphological alterations were induced by high K+ and dopamine, which caused release of endogenous glutamate and subsequent activation of AMPA-kainate receptors. Apparently, retinal glutamatergic transmission is accompanied by neuronal cell swelling that causes compensatory morphological alterations of glial cells. The effect of dopamine was elicitable only during light adaptation but not in the dark, and glutamate and high K+ induced strong ereffects in the dark than in the light. This suggests that not only the endogenous release of dopamine but also the responsiveness of glutamatergic neurons to dopamine is regulated by light-dark adaptation. Similar morphological alterations (neuronal swelling and decreased glial process thickness) were observed in whole mounts isolated immediately after experimental retinal ischemia, suggesting an involvement of AMPA-kainate receptor activation in putative neurotoxic cell swelling in the postischemic retina.

Signalling of sphingosine-1-phosphate in Müller glial cells via the S1P/EDG-family of G-protein-coupled receptors.

Signalling of sphingosine-1-phosphate (S1P) via G-protein-coupled receptors of the Endothelial Differentiation Gene family differentially regulates cellular processes such as migration, proliferation and morphogenesis in a variety of cell types. Proliferation and migration of retinal Müller glial cells are involved in pathological events such as proliferative vitreoretinopathy and proliferative diabetic retinopathy. Investigation of possible functional roles of S1P receptors might thus open new insights into Müller cell pathophysiology. Here we show that cultured Müller cells from the guinea pig retina respond to application of S1P with an increase in the intracellular calcium content in a concentration-dependent manner (EC(50) 11nM). This calcium increase consists of two components; an initial fast peak and a slow plateau component. The initial transient is caused by a release of calcium from intracellular stores and is suppressed by U-73122, a selective phospholipase C inhibitor. The slow plateau component is caused by a calcium influx. These results suggest that the S1P-induced calcium response in Müller cells partially involves signalling via G-protein-coupled receptors. Moreover, S1P slightly induced Müller cell migration but no proliferation. Thus, the data indicate that Müller cells might be involved in S1P signalling in the retina.