Keele University

About: Keele University is a education organization based out in Newcastle-under-Lyme, United Kingdom. It is known for research contribution in the topics: Population & Stars. The organization has 11318 authors who have published 26323 publications receiving 894671 citations. The organization is also known as: Keele University.

Predictions for mass-loss rates and terminal wind velocities of massive O-type stars

Abstract: Mass loss forms an important aspect of the evolution of massive stars, as well as for the enrichment of the surrounding ISM. Our goal is to predict accurate mass-loss rates and terminal wind velocities. These quantities can be compared to empirical values, thereby testing radiation-driven wind models. One specific issue is that of the "weak-wind problem", where empirically derived mass-loss rates fall orders of magnitude short of predicted values. We employ an established Monte Carlo model and a recently suggested new line acceleration formalism to solve the wind dynamics consistently. We provide a new grid of mass-loss rates and terminal wind velocities of O stars, and compare the values to empirical results. Our models fail to provide mass-loss rates for main-sequence stars below a luminosity of log(L/Lsun) = 5.2, where we run into a fundamental limit. At luminosities below this critical value there is insufficient momentum transferred in the region below the sonic point to kick-start the acceleration. This problem occurs at the location of the onset of the weak-wind problem. For O dwarfs, the boundary between being able to start a wind, and failing to do so, is at spectral type O6/O6.5. The direct cause of this failure is a combination of the lower luminosity and a lack of Fe V lines at the wind base. This might indicate that another mechanism is required to provide the necessary driving to initiate the wind. For stars more luminous than log(L/Lsun) = 5.2, our new mass-loss rates are in excellent agreement with the mass-loss prescription by Vink et al. 2000. This implies that the main assumption entering the method of the Vink et al. prescriptions - i.e. that the momentum equation is not explicitly solved for - does not compromise the reliability of the Vink et al. results for this part of parameter space (Abridged).

Basic biology of tendon injury and healing

Abstract: Tendon disorders are commonly seen in clinical practice Their successful treatment is difficult and patients often experience symptoms for prolonged periods of time At present the aetiology of tendon disorders remains unclear, with several factors having been implicated An improved understanding of tendon injury and healing is essential to enable focused treatment strategies to be devised

Prospective study of the incidence, nature and causes of dispensing errors in community pharmacies

Abstract: Background Each year over 600 million prescription items are dispensed in community pharmacies in England and Wales. Despite this, there is little published evidence relating to dispensing errors and near misses occurring in this setting. This study sought to determine their incidence, nature and causes. Methods Prospective study over a 4-week period in 35 community pharmacies (9 independent pharmacies and 26 chain pharmacies) in the UK. Pharmacists recorded details of all incidents that occurred during the dispensing process, including information about: the stage at which the error was detected; who found the error; who made the error; type of error; reported cause of error and circumstances associated with the error. Results 125 395 prescribed items were dispensed during the study period and 330 incidents were recorded relating to 310 prescriptions. 280 (84.8%) incidents were classified as a near miss (rate per 10 000 items dispensed =22.33, 95%CI 19.79–25.10), while the remaining 50 (15.2%) were classified as dispensing errors (rate per 10 000 items dispensed =3.99, 95%CI 2.96–5.26). Selection errors were the most common types of incidents (199, 60.3%), followed by labeling (109, 33.0%) and bagging errors (22, 6.6%). Most of the incidents were caused either by misreading the prescription (90, 24.5%), similar drug names (62, 16.8%), selecting the previous drug or dose from the patient's medication record on the pharmacy computer (42, 11.4%) or similar packaging (28, 7.6%). Conclusions This study has demonstrated that a wide range of medication errors occur in community pharmacies. On average, for every 10 000 items dispensed, there are around 22 near misses and four dispensing errors. Given the current plans for reporting adverse events in the NHS, greater insight into the likely incidence and nature of dispensing errors will be helpful in designing effective risk management strategies in primary care. Copyright © 2004 John Wiley & Sons, Ltd.

Anticancer agents coupled to N-(2-hydroxypropyl)methacrylamide copolymers. I. Evaluation of daunomycin and puromycin conjugates in vitro

Abstract: During recent years N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers have been developed as targetable drug carriers. These soluble synthetic polymers are internalized by cells by pinocytosis and they can be tailor-made to include peptidyl side-chains degradable intracellularly by specific lysosomal enzymes. Thus they provide the opportunity fo achieve controlled intracellular delivery of anticancer agents. The anthracycline antibiotic daunomycin, and protein synthesis inhibitor puromycin, were bound to HPMA copolymers via several different peptide side-chains, including Gly-Gly, Gly-Phe-Leu-Gly and Gly-Phe-Phe-Leu. Incubation of polymer-drug conjugates with isolated lysosomal enzymes (either a mixture of rat liver lysosomal enzymes or purified thiol-dependent lysosomal proteinases, cathepsins L and B) showed that significant release of drug occurred over 20 h, more than 20% of daunomycin and more than 80% of puromycin being liberated. To test their pharmacological activity conjugates were incubated with either the mouse leukaemia L1210, or the human lymphoblastoid leukaemia CCRF in vitro. The conjugates tested were all less effective than free daunomycin, but they showed differential toxicity against L1210 depending on the aminoacid sequence of their drug-polymer linkage. Inclusion of fucosylamine-terminating side-chains into the HPMA copolymer structure increased the affinity of conjugates for the L1210 cell membrane and resulted in increased toxicity. In contrast HPMA-daunomycin conjugates with or without fucosylamine affected CCRF cells equally, but this cell line was more sensitive than the mouse leukaemia to both free and polymer-bound daunomycin. Incubation of L1210 cells in polymer-bound daunomycin for 72 h, followed by plating cells out in low density in drug-free medium, showed that a concentration of polymer-bound drug (184 micrograms ml-1) could be selected to achieve a cytotoxic effect.