Intervertebral disc cells as competent phagocytes in vitro: implications for cell death in disc degeneration

INTRODUCTION: Apoptosis has been reported to occur in the intervertebral disc. Elsewhere in the body, apoptotic cells are cleared from the system via phagocytosis by committed phagocytes such as macrophages, reducing the chance of subsequent inflammation. These cells, however, are not normally present in the disc. We investigated whether disc cells themselves can be induced to become phagocytic and so have the ability to ingest and remove apoptotic disc cells, minimising the damage to their environment. METHOD: Bovine nucleus pulposus cells from caudal intervertebral discs were grown in culture and exposed to both latex particles (which are ingested by committed phagocytes) and apoptotic cells. Their response was monitored via microscopy, including both fluorescent and video microscopy, and compared with that seen by cell lines of monocytes/macrophages (THP-1 and J774 cells), considered to be committed phagocytes, in addition to a nonmacrophage cell line (L929 fibroblasts). Immunostaining for the monocyte/macrophage marker, CD68, was also carried out. RESULTS: Disc cells were able to ingest latex beads at least as efficiently, if not more so, than phagocytic THP-1 and J774 cells. Disc cells ingested a greater number of beads per cell than the committed phagocytes in a similar time scale. In addition, disc cells were able to ingest apoptotic cells when cocultured in monolayer with a UV-treated population of HeLa cells. Apoptotic disc cells, in turn, were able to stimulate phagocytosis by the committed macrophages. CD68 immunostaining was strong for THP-1 cells but negligible for disc cells, even those that had ingested beads. CONCLUSION: In this study, we have shown that intervertebral disc cells are capable of behaving as competent phagocytes (that is, ingesting latex beads) and apoptotic cells. In terms of number of particles, they ingest more than the monocyte/macrophage cells, possibly due to their greater size. The fact that disc cells clearly can undergo phagocytosis has implications for the intervertebral disc in vivo. Here, where cell death is reported to be common yet there is normally no easy access to a macrophage population, the endogenous disc cells may be encouraged to undergo phagocytosis (for example, of neighbouring cells within cell clusters)

Noyal-sur-Vilaine – Le Bois Orcan, une étude pluridisciplinaire

Les fouilles de 1998 au Bois Orcan font partie d’une étude pluridisciplinaire intitulée « les bâtiments domestiques seigneuriaux de Bretagne », commencée au début des années 1980, et qui comporte trois directions principales : l’étude architecturale et archéologique du bâti, l’examen des archives écrites et iconographiques, la datation par la dendrochronologie de bâtiments choisis et des fouilles. Ce projet de recherche est sous la direction du professeur Meirion-Jones (université de Reading)..

The Statistical Approach to Quantifying Galaxy Evolution

Studies of the distribution and evolution of galaxies are of fundamental importance to modern cosmology; these studies, however, are hampered by the complexity of the competing effects of spectral and density evolution. Constructing a spectroscopic sample that is able to unambiguously disentangle these processes is currently excessively prohibitive due to the observational requirements. This paper extends and applies an alternative approach that relies on statistical estimates for both distance (z) and spectral type to a deep multi-band dataset that was obtained for this exact purpose. These statistical estimates are extracted directly from the photometric data by capitalizing on the inherent relationships between flux, redshift, and spectral type. These relationships are encapsulated in the empirical photometric redshift relation which we extend to z ~ 1.2, with an intrinsic dispersion of dz = 0.06. We also develop realistic estimates for the photometric redshift error for individual objects, and introduce the utilization of the galaxy ensemble as a tool for quantifying both a cosmological parameter and its measured error. We present deep, multi-band, optical number counts as a demonstration of the integrity of our sample. Using the photometric redshift and the corresponding redshift error, we can divide our data into different redshift intervals and spectral types. As an example application, we present the number redshift distribution as a function of spectral type.Comment: 40 pages (LaTex), 21 Figures, requires aasms4.sty; Accepted by the Astrophysical Journa

Agreement between ophthalmologists and optometrists in the certification of vision impairment

Background/objectives The certification process to register patients as sight impaired or severely sight impaired is undertaken by consultant ophthalmologists, in the UK. We sought to assess the agreement between optometrists and a consensus panel, in identifying patient eligibility for certification, relative to the agreement between ophthalmologists and the consensus panel. Methods The consensus panel (4 consultant ophthalmologists and 3 optometrists with a formal accreditation in low vision), 30 consultant ophthalmologists and 99 low vision optometrists reviewed 40 randomly selected abridged cases. The eligibility outcomes from the ophthalmologists and the optometrists were compared with the consensus panel outcomes. Results For ophthalmologists and optometrists, the median (IQR) number of cases in which there was agreement with the consensus panel was 33.0 (31.0, 33.0) and 36.0 (34.0, 36.5), respectively. In severely sight impaired cases, the probabilities of agreeing on eligibility for certification were 76.0% (95% CIs 71.4%, 80.1%) for ophthalmologists and 61.8% (59.0%, 64.6%) for optometrists. In sight impaired cases, the corresponding values were 51.6% (46.7%, 56.4%) for ophthalmologists and 72.2% (69.8%, 74.5%) for optometrists. In cases of bilateral atrophic age-related macular degeneration (AMD), both groups were more likely to agree with the consensus panel and the differences between optometrists and ophthalmologists were less marked. Conclusions Optometrists demonstrated a comparable agreement relative to ophthalmologists, with the consensus panel on the eligibility of randomly selected, abridged cases for certification. The findings support the clinical decision-making ability of low vision optometrists in the certification of patients with vision impairment and provide evidence in support of policy change to allow low vision optometrists to certify individuals with atrophic AMD

Estimating photometric redshifts with artificial neural networks

A new approach to estimating photometric redshifts - using Artificial Neural Networks (ANNs) - is investigated. Unlike the standard template-fitting photometric redshift technique, a large spectroscopically-identified training set is required but, where one is available, ANNs produce photometric redshift accuracies at least as good as and often better than the template-fitting method. The Bayesian priors on the underlying redshift distribution are automatically taken into account. Furthermore, inputs other than galaxy colours - such as morphology, angular size and surface brightness - may be easily incorporated, and their utility assessed. Different ANN architectures are tested on a semi-analytic model galaxy catalogue and the results are compared with the template-fitting method. Finally the method is tested on a sample of ~ 20000 galaxies from the Sloan Digital Sky Survey. The r.m.s. redshift error in the range z < 0.35 is ~ 0.021.Comment: Submitted to MNRAS, 9 pages, 9 figures, substantial improvements to paper structur