The biogenesis of erythropoietin during inflammation

Anaemia frequently accompanies chronic inflammatory diseases like rheumatoid arthritis and cancer. It is postulated to result primarily from the suppression of erythropoiesis by inflammatory cytokines. A contributing factor could be the inhibition of erythropoietin synthesis which may also be mediated by cytokines. Erythropoietin is the hormone which regulates erythropoiesis. The aims of this project were to investigate whether cytokines can indeed suppress erythropoietin production, and to determine whether the erythropoietin response in experimental models of acute and chronic inflammation was appropriate for the associated anaemia. Macrophage-conditioned medium, interleukin-1β, interleukin-6, tumour necrosis factor-α, and neopterin were assayed for inhibition of erythropoietin synthesis by HepG2 cells in culture. All, except neopterin, effected dose-dependent reductions in the secretion of the hormone. Interleukin-1β and tumour necrosis factor-α down-regulated erythropoietin gene transcription, whereas interleukin-6 inhibited a post-transcriptional process. Rats with acute inflammation developed a mild anaemia which evoked an increase in their serum levels of erythropoietin. The serum erythropoietin levels were optimal, since rats with acute inflammation and severe phenylhydrazine-induced anaemia did not have lower levels of the hormone than controls with a similar degree of anaemia, but without acute inflammation. Erythropoietin is, therefore, not an acute phase reactant. Mice with cancer developed a progressive anaemia which was not due to bone marrow invasion by tumour cells. During the first fourteen days after inoculating them with cancer cells, the mice responded by increasing their serum levels of erythropoietin as the anaemia worsened. The erythropoietin response was appropriate when compared to mice with the same degree of phenylhydrazine-induced anaemia. Erythropoietin levels measured in mice with tumours older than fourteen days were significantly lower than those of control mice with the same degree of experimental anaemia. These animals were very cachectic, suggesting that a blunted erythropoietin response may depend on disease activity

Spatio-temporal mapping of variation potentials in leaves of Helianthus annuus L. seedlings in situ using multi-electrode array.

Damaging thermal stimuli trigger long-lasting variation potentials (VPs) in higher plants. Owing to limitations in conventional plant electrophysiological recording techniques, recorded signals are composed of signals originating from all of the cells that are connected to an electrode. This limitation does not enable detailed spatio-temporal distributions of transmission and electrical activities in plants to be visualised. Multi-electrode array (MEA) enables the recording and imaging of dynamic spatio-temporal electrical activities in higher plants. Here, we used an 8 × 8 MEA with a polar distance of 450 μm to measure electrical activities from numerous cells simultaneously. The mapping of the data that were recorded from the MEA revealed the transfer mode of the thermally induced VPs in the leaves of Helianthus annuus L. seedlings in situ. These results suggest that MEA can enable recordings with high spatio-temporal resolution that facilitate the determination of the bioelectrical response mode of higher plants under stress

Oxytocin, feeding, and satiety

Oxytocin neurones have a physiological role in food intake and energy balance. Central administration of oxytocin is powerfully anorexigenic, reducing food intake and meal duration. The central mechanisms underlying this effect of oxytocin have become better understood in the past few years. Parvocellular neurones of the paraventricular nucleus project to the caudal brainstem to regulate feeding via autonomic functions including the gastrointestinal vago-vagal reflex. In contrast, magnocellular neurones of the supraoptic and paraventricular nuclei release oxytocin from their dendrites to diffuse to distant hypothalamic targets involved in satiety.The ventromedial hypothalamus, for example, expresses a high density of oxytocin receptors but does not contain detectable oxytocin nerve fibres. Magnocellular neurones represent targets for the anorexigenic neuropeptide α-melanocyte stimulating hormone. . In addition to homeostatic control, oxytocin may also have a role in reward-related feeding. Evidence suggests that oxytocin can selectively suppress sugar intake and that it may have a role in limiting the intake of palatable food by inhibiting the reward pathway

Optimization of superstructured fiber bragg gratings for microwave photonic filters response

The microwave photonic responses of superstructured fiber Bragg gratings in combination with dispersive fiber are investigated theoretically and experimentally. The superstructured gratings are optimized, taking account of the spectral response of the broad-band source, Erbium-doped fiber amplifier, and optical tunable filter to achieve a filter response with sidelobe suppression of more than 60 dB. © 2004 IEEE

Laser range finding using the self-mixing effect in a vertical-cavity surface-emitting laser

In this paper we report on a laser range finding system built using the self-mixing effect in a Vertical-Cavity Surface-Emitting Laser (VCSEL). The distance to the target in these range finders is usually calculated by determining the time interval between the peaks in the resulting power fluctuations that are produced by the self-mixing effect. In this study we propose the use of a method that utilises the Fast Fourier Transform (FFT) that proves to have better performance than the traditional peak spacing methods used by other researchers. A range finding system has been built using a VCSEL and the FFT to measure a range of distances from 20cm to 1m with a maximum error of 1.5% and a resolution of 5mm. This is the first time to our knowledge that such a range finding system has been built with a VCSEL

A new method for microwave generation and data transmission using DFB laser based on fiber bragg gratings

A novel architecture for microwave/millimeter-wave signal generation and data modulation using a fiber-grating-based distributed feedback laser has been proposed in this letter. For demonstration, a 155.52-Mb/s data stream on a 16.9-GHz subcarrier has been transmitted and recovered successfully. It has been proved that this technology would be of benefit to future microwave data transmission systems. © 2006 IEEE

Risks associated with endotoxins in feed additives produced by fermentation

Acknowledgements We thank Jordi Tarrés Call, who recorded the discussions and offered advice about procedures, and Nicole Reisinger and Gerd Schatzmayr, who provided valuable information about endotoxins in animal feeds. The Rowett Institute of Nutrition and Health is funded by the Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government.Peer reviewedPublisher PD