Factors determining the risk of diabetes foot amputations - a retrospective analysis of a tertiary diabetes foot care service

Aims: To identify which factors predict the need for minor or major amputation in patients attending a multidisciplinary diabetic foot clinic. Methods: A retrospective analysis of patients who attended over a 27 month period were included. Patients had to have attended ≥3 consecutive consultant led clinic appointments within 6 months. Data was collected on HbA1c, clinic attendance, blood pressure, peripheral arterial disease (PAD), and co-morbidities. Patients were followed up for 1 year. Results: 165 patients met the inclusion criteria. 121 were male. 33 patients had amputations. There was an association between poor glycaemic control at baseline and risk of amputation when adjusted for other factors, with those patients having HbA1c ≤58 at less risk of amputation with an odds of 0.14 (0.04 to 0.53) of amputation(p = 0.0036). Other statistically significant factors predictive of amputation were: missing clinic appointments (p = 0.0079); a high Charlson index (p = 0.03314); hypertension (p = 0.0216). No previous revascularisation was protective against amputation (p = 0.0035). However PAD was not seen to be statistically significant, although our results indicated a lower risk of amputation with no PAD. Overall, 34.9% (n = 58) of patients had good glycaemic control (HbA1c <58 mmol/mol) at baseline & 81.3% (n = 135) had improved their glycaemic control at their last follow up appointment. Conclusions: In this cohort poor glycaemic control, poor attendance, previous revascularisation & hypertension were associated with higher risk of amputation, with PAD showing a trend. Moreover, we demonstrated benefits in glycaemic control achieved by attending this DFC, which is likely to translate to longer term diabetes related health benefits

Concept of Formation Length in Radiation Theory

The features of electromagnetic processes are considered which connected with finite size of space region in which final particles (photon, electron-positron pair) are formed. The longitudinal dimension of the region is known as the formation length. If some external agent is acting on an electron while traveling this distance the emission process can be disrupted. There are different agents: multiple scattering of projectile, polarization of a medium, action of external fields, etc. The theory of radiation under influence of the multiple scattering, the Landau-Pomeranchuk-Migdal (LPM) effect, is presented. The probability of radiation is calculated with an accuracy up to "next to leading logarithm" and with the Coulomb corrections taken into account. The integral characteristics of bremsstrahlung are given, it is shown that the effective radiation length increases due to the LPM effect at high energy. The LPM effect for pair creation is also presented. The multiple scattering influences also on radiative corrections in a medium (and an external field too) including the anomalous magnetic moment of an electron and the polarization tensor as well as coherent scattering of a photon in a Coulomb field. The polarization of a medium alters the radiation probability in soft part of spectrum. Specific features of radiation from a target of finite thickness include: the boundary photon emission, interference effects for thin target, multi-photon radiation. The experimental study of LPM effect is described. For electron-positron colliding beams following items are discussed: the separation of coherent and incoherent mechanisms of radiation, the beam-size effect in bremsstrahlung, coherent radiation and mechanisms of electron-positron creation.Comment: Revised review paper, 96 pages, 28 figures. Description of SLAC E-146 experiment removed, discussion of CERN SPS experiment adde

Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea)

Rose-Bengal-stained foraminiferal assemblages (> 150 μm) were analysed along a five-station bathymetric transect across the core and the lower part of the oxygen minimum zone (OMZ) on the Indian margin of the Arabian Sea. Sediment cores were collected using the manned submersible Shinkai 6500 during the RV Yokosuka cruise YK08-11 in the post-monsoon season (October 2008) at water depths ranging from 535 to 2000 m, along a gradient from almost anoxic to well-oxygenated (0.3 to 108 μM) bottom waters. Stained benthic foraminifera were investigated from two different size fractions (150–300 μm and > 300 μm). Stained foraminiferal densities were very high in the core of the OMZ (at 535 and 649 m) and decreased at deeper sites. The faunas (> 150 μm) were dominated (40–80 %) by non-calcareous taxa at all stations. These were mainly species of Reophax and Lagenammina but also included delicate monothalamous taxa (organic-walled "allogromiids", agglutinated saccamminids, psammosphaerids and tubular forms). These new data from the Indian margin are compared to previous studies from the Murray Ridge, the Pakistan margin and the Oman margin. The fact that similar species were found at sites with comparable bottom-water oxygen concentrations but with very different surface water productivity suggests that, within the strongly developed Arabian Sea OMZ, bottom-water oxygen concentration, and not the organic flux to the sea floor, is the main factor controlling the species composition of the foraminiferal communities. Several foraminiferal species (e.g. Praeglobobulimina sp. 1, Ammodiscus sp. 1, Bolivina aff. dilatata) were confined to the core of the OMZ. These species are presently known only from the Arabian Sea. Because of their association with extremely low oxygen concentrations, these species may be good markers for very low oxygen concentrations, and could be used to reconstruct past OMZ variability in the Arabian Sea

The trophic and metabolic pathways of foraminifera in the Arabian Sea: evidence from cellular stable isotopes

The Arabian Sea is a region of elevated productivity with the highest globally recorded fluxes of particulate organic matter (POM) to the deep ocean, providing an abundant food source for fauna at the seafloor. However, benthic communities are also strongly influenced by an intense oxygen minimum zone (OMZ), which impinges on the continental slope from 100 to 1000 m water depth. We compared the trophic ecology of foraminifera on the Oman and Pakistan margins of the Arabian Sea (140–3185 m water depth). These two margins are contrasting both in terms of the abundance of sedimentary organic matter and the intensity of the OMZ. Organic carbon concentrations of surficial sediments were higher on the Oman margin (3.32 ± 1.4%) compared to the Pakistan margin (2.45 ± 1.1%) and sedimentary organic matter (SOM) quality estimated from the Hydrogen Index was also higher on the Oman margin (300–400 mg HC mg TOC−1) compared to the Pakistan margin (< 250 mg HC mg TOC−1). The δ13C and δ15N values of sediments were similar on both margins (−20 and 8‰, respectively). Stable isotope analysis (SIA) showed that foraminiferal cells had a wide range of δ13C values (−25.5 to −11.5‰), implying that they utilise multiple food sources; indeed δ13C values varied between depths, foraminiferal types and between the two margins. Foraminifera had broad ranges in δ15N values (−7.8 to 27.3‰). The enriched values suggest that some species may store nitrate to utilise in respiration; this was most notable on the Pakistan margin. Depleted foraminiferal δ15N values, particularly at the Oman margin, may reflect feeding on chemosynthetic bacteria. We suggest that differences in productivity regimes may be responsible for the differences observed in foraminiferal isotopic composition. In addition, at the time of sampling, whole jellyfish carcasses (Crambionella orsini) and a carpet of jelly detritus were observed across the Oman margin transect. Associated chemosynthetic bacteria may have provided an organic-rich food source for foraminifera at these sites. Our data suggest that foraminifera in OMZ settings can utilise a variety of food sources and metabolic pathways to meet their energetic demands

Contribution de la culture des foraminifères benthiques à la calibration de proxies paléocéanographiques

Grâce aux connaissances acquises sur les conditions idéales de culture de différentes espèces de foraminifères benthiques, il est désormais possible de réaliser des calibrations de proxies paléocéanographiques en laboratoire. Plusieurs expériences ont déjà été réalisées : 1) Calibration du δ18O de foraminifères benthiques profonds (Barras et al., 2010) La culture de Bulimina marginata en conditions contrôlées à différentes températures (4 à 19°C) a permis de démontrer que l’effet de la température sur le δ18O de cette espèce est semblable à l’effet thermodynamique enregistré pour la calcite inorganique. Nous avons pu mettre en évidence également un effet ontogénétique non négligeable pour les études de reconstitutions paléoclimatiques. 2) Calibration du Mg/Ca de coquilles de Hyalinea balthica (Rosenthal et al., 2011) La calcification de nouvelles loges de H. balthica à différentes températures (8, 10 et 13°C) a permis de mesurer, à l’aide de l’ablation laser ICP-MS, un effet d’environ 12%/°C sur la concentration en Mg/Ca. Ces résultats confirment la calibration in situ réalisée pour cette espèce qui se trouve avoir une sensibilité 4 fois supérieure à celle des autres espèces benthiques profondes. 3) Effet de la salinité sur le δ18O, le Mg/Ca et le Sr/Ca d’une espèce côtière (Diz et al., 2012) La culture d’Ammonia tepida en conditions contrôlées à différentes salinités (29.8, 32.2, 35.5) n’a pas montré d’effet significatif de ce paramètre sur la composition isotopique et en éléments traces de la calcite. Par contre, ces expériences ont permis de mettre en évidence un effet de la taille des individus sur la composition en Sr/Ca et une forte variabilité des mesures de Mg/Ca entre les coquilles d’individus ayant calcifié dans les mêmes conditions. 4) Effet de la nourriture sur le δ13C d’espèces intertidales (Mojtahid et al., 2011) Des expériences menées en laboratoire sur des coquilles adultes de Hyanesina germanica et A. beccarii avec de la nourriture labélisée radioactivement (3H et 14C) ont montré que très peu de carbone ingéré est incorporé dans la coquille. Cependant, aucun des spécimens n’a formé de nouvelles loges pendant les expériences ce qui ne permet pas une conclusion définitive sur l’influence de la nourriture sur la signature isotopique de la calcite. Ceci ouvre les portes à d’autres expériences sur des juvéniles avec le même protocole qui s’est avéré très approprié. Ces études ont démontré l’utilité de réaliser des calibrations de proxies en laboratoire. Nous prévoyons de poursuivre ce travail en travaillant au développement de nouveaux proxies de paléo-oxygénation grâce au programme de recherche régional MADONA

Patterns of eukaryotic diversity from the surface to the deep-ocean sediment

Remote deep-ocean sediment (DOS) ecosystems are among the least explored biomes on Earth. Genomic assessments of their biodiversity have failed to separate indigenous benthic organisms from sinking plankton. Here, we compare global-scale eukaryotic DNA metabarcoding datasets (18S-V9) from abyssal and lower bathyal surficial sediments and euphotic and aphotic ocean pelagic layers to distinguish plankton from benthic diversity in sediment material. Based on 1685 samples collected throughout the world ocean, we show that DOS diversity is at least threefold that in pelagic realms, with nearly two-thirds represented by abundant yet unknown eukaryotes. These benthic communities are spatially structured by ocean basins and particulate organic carbon (POC) flux from the upper ocean. Plankton DNA reaching the DOS originates from abundant species, with maximal deposition at high latitudes. Its seafloor DNA signature predicts variations in POC export from the surface and reveals previously overlooked taxa that may drive the biological carbon pump

Is the meiofauna a good indicator for climate change and anthropogenic impacts?

Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research