Search results for " Sickle"
showing 8 items of 18 documents
An antler sickle from the Neolithic site of Costamar at Cabanes (Castellón) on the Mediterranean Spanish coast
2012
Archaeological excavations at the settlement of Costamar between 2006 and 2008 by the Fundació Marina d'Or uncovered an area of 57 905m² containing 683 archaeological features belonging to Neolithic, Bronze Age, Iberian, Roman, Islamic, late medieval, modern and contemporary times. The Neolithic features belong to two phases. The first, with 203 storage pits, is characterised by the presence of pottery with incised-impressed decoration combined with plastic decoration and pigmentation with red ochre. One outstanding nearly complete vessel is decorated with an anthropomorphic motif. This phase has been dated by a cattle bone (Bos Taurus) to 5996±38 (4990–4790 cal BC at 2σ) and by a grain of …
Time scale of protein aggregation dictated by liquid-liquid demixing
2003
The growing impact of protein aggregation pathologies, together with the current high need for extensive information on protein structures are focusing much interest on the physics underlying the nucleation and growth of protein aggregates and crystals. Sickle Cell Hemoglobin (HbS), a point-mutant form of normal human Hemoglobin (HbA), is the first recognized and best-studied case of pathologically aggregating protein. Here we reanalyze kinetic data on nucleation of deoxy-HbS aggregates by referring them to the (concentration-dependent) temperature Ts characterizing the occurrence of the phase transition of liquid-liquid demixing (LLD) of the solution. In this way, and by appropriate scalin…
Effect of T-R conformational change on sickle-cell hemoglobin interactions and aggregation
2004
We compare the role of a conformational switch and that of a point mutation in the thermodynamic stability of a protein solution and in the consequent propensity toward aggregation. We study sickle-cell hemoglobin (HbS), the beta6 Glu-Val point mutant of adult human hemoglobin (HbA), in its R (CO-liganded) conformation, and compare its aggregation properties to those of both HbS and HbA in their T (unliganded) conformation. Static and dynamic light scattering measurements performed for various hemoglobin concentrations showed critical divergences with mean field exponents as temperature was increased. This allowed determining spinodal data points T(S)(c) by extrapolation. These points were …
Spinodal lines and Flory-Huggins free-energies for solutions of human hemoglobins HbS and HbA
1991
Gelation of deoxygenated solutions of sickle-cell human Hemoglobin (HbS) is of high theoretical interest and it has serious pathological consequences. For this reason HbS is probably the most studied protein capable of self-organization. This notwithstanding, the location in the T, c plane of the region of thermodynamic instability of solutions of deoxy-HbS (as bounded by the spinodal line and as distinct from the gelation region) has remained unknown, along with related values of Flory-Huggins enthalpies and entropies. In the present work this information is derived from experiments for the two cases of (deoxy) HbS and of human adult hemoglobin (HbA). Experiments also show critical exponen…
Quantifying cereal-reaping microwear on flint tools : an experimental approach
2016
International audience; From the earliest Neolithic in the Near East to the last Chalcolithic cultures in Western Europe, certain flint tools have been used as sickles to harvest cereals. Such harvesting tools can be identified through use-wear analyses, because cutting herbaceous plants produces specific wear-traces on the working edge of flint blades. The aim of this work is to explore harvesting-driven microwear variability and, more particularly, intensity of use as a governing factor. To achieve this objective, an experiment was designed consisting in the production of flint replicas to be used as harvesting tools, in various controlled conditions. A simple, cost-effective method of qu…
The role of pH on instability and aggregation of sickle hemoglobin solutions
2004
Understanding the physical basis of protein aggregation covers strong physical and biomedical interests. Sickle hemoglobin (HbS) is a point-mutant form of normal human adult hemoglobin (HbA). It is responsible for the first identified "molecular disease," as its propensity to aggregation is responsible for sickle cell disease. At moderately higher than physiological pH value, this propensity is inhibited: The rate of aggregate nucleation becomes exceedingly small and solubility after polymerization increases. These order-of-magnitude effects on polymer nucleation rates and concurrent relatively modest changes of solubility after polymerization are here shown to be related to both pH-induced…
Time trends, sociodemographic and health factors associated with discharge and length of stay of hospitalised patients with sickle cell disease in Gh…
2021
ObjectivePatients with sickle cell disease (SCD) are prone to multiple episodes resulting in frequent hospital visits. We determined the time trends, sociodemographic and health factors associated with length of stay (LoS) for patients with SCD in Ghana.Design, participants, settingWe retrospectively analysed SCD hospitalisation records of 22 680 patients from a nationwide database of the Ghana Health Service from 2012 to 2017.Outcome measuresFactors associated with LoS were estimated using Cox regression, while the cumulative incidence of being discharged alive was estimated with in-hospital death as a competing risk.ResultsPatients admitted for SCD over 6 years constituted 22 680 (0.8%) o…
Chelation treatment in sickle-cell-anaemia: much ado about nothing?
2011
Summary Blood transfusions may prevent and treat serious complications related to sickle-cell disease (SCD) when performed according to specific guidelines. However, blood transfusion requirements in SCD inevitably lead to increased body iron burden. An adequate chelation treatment may prevent complications and reduce morbidity and mortality. This review evaluates the effectiveness, safety and costs of chelation treatment. The included trials were examined according to the recommendations of the American College of Cardiology (ACC) and the American Heart Association (AHA). Overall, 14 trials and a total of 502 patients with SCD were included in this review. Deferoxamine alone (s.c. or i.v.)…