The behaviour of 226Ra in high-volume environmental water samples on TK100 resin.

Accurate, low-level measurement of 226Ra in high volume water samples requires rapid pre-concentration and robust separation techniques prior to measurement in order to comply with discharge limits and drinking water regulations. This study characterises the behaviour of 226Ra and interfering elements on recently developed TK100 (Triskem International) extraction chromatography resin. Distribution coefficients over a range of acid concentrations are given, along with an optimised procedure that shows rapid pre-concentration and separation of 226Ra on TK100 resin is achievable for high volume (1 L) water samples without the need for sample pre-treatment.

Evaluation of the separation and purification of 227Th from its decay progeny by anion exchange and extraction chromatography.

Thorium-227 is currently undergoing evaluation as a potential radionuclide for targeted cancer therapy, and as such a high chemical purity of the material is required. To establish a reliable procedure for radiochemical isolation of 227Th from the parent 227Ac and decay progeny, which includes the radiotherapeutic 223Ra, the performance of three different separation schemes based on ion-exchange and extraction chromatography have been evaluated. The results suggest that both ion exchange and extraction chromatographic techniques can be successfully used for the separation of 227Th from its decay progeny, however extraction chromatographic resins demonstrate favourable performance in terms of Th recovery and purification from radionuclide impurities.

Predatory blue crabs induce stronger nonconsumptive effects in eastern oysters Crassostrea virginica than scavenging blue crabs.

By influencing critical prey traits such as foraging or habitat selection, predators can affect entire ecosystems, but the nature of cues that trigger prey reactions to predators are not well understood. Predators may scavenge to supplement their energetic needs and scavenging frequency may vary among individuals within a species due to preferences and prey availability. Yet prey reactions to consumers that are primarily scavengers versus those that are active foragers have not been investigated, even though variation in prey reactions to scavengers or predators might influence cascading nonconsumptive effects in food webs. Oysters Crassostrea virginica react to crab predators by growing stronger shells. We exposed oysters to exudates from crabs fed live oysters or fed aged oyster tissue to simulate scavenging, and to controls without crab cues. Oysters grew stronger shells when exposed to either crab exudate, but their shells were significantly stronger when crabs were fed live oysters. The stronger response to predators than scavengers could be due to inherent differences in diet cues representative of reduced risk in the presence of scavengers or to degradation of conspecific alarm cues in aged treatments, which may mask risk from potential predators subsisting by scavenging.

Development of an optimised method for analysis of 90Sr in decommissioning wastes by triple quadrupole inductively coupled plasma mass spectrometry.

The ongoing development of an optimised procedure for the measurement of 90Sr in decommissioning samples using the latest generation triple quadrupole inductively coupled plasma mass spectrometry (ICP-QQQ-MS) is presented. The procedure incorporates digestion, and separation from interferences using a combination of wet chemical and instrument-based separation using the ICP-QQQ-MS reaction cell. The key factors under study are the procedural time and limits of detection achievable compared to existing radiometric techniques.

[Neostigmine-induced neuromuscular blockade in the corrugator supercilii muscle]. / Bloqueo neuromuscular inducido por neostigmina en el músculo Corrugator supercilii.

OBJECTIVE: To investigate whether a single dose of neostigmine, administered when the adductor pollicis muscle presents 2 twitches in train-of-four (TOF) stimulation, can reduce the TOF ratio in the corrugator supercilii muscle. PATIENTS AND METHODS: We designed a case-control study of patients between 18 and 65 years of age classified ASA 1-2. We used 2 accelerometers--1 for the cubital nerve/thumb adductor muscle and 1 for the facial nerve/corrugator supercilii muscle. Neuromuscular blockade was induced with 0.6 mg x kg(-1) of rocuronium, and 40 microg x kg(-1) of neostigmine was administered at the third twitch in the TOF in the thumb adductor. If the TOF ratio in the corrugator supercilii fell by 10% or more at that time, the patient was classified as a case. We recorded the age, sex, weight, height, body mass index, duration of the procedure, and TOF ratio in the corrugator supercilii muscle when the neostigmine was administered. RESULTS: Ten cases and 10 controls were enrolled. No significant differences between cases and controls were found in any variables except the mean (SD) TOF ratio in the corrugator supercilii muscle: 70.9% (17.8%) in cases and 35.3% (7.8%) in controls (P < .001). CONCLUSIONS: In our patients, administration of neostigmine after the appearance of the third twitch in TOF stimulation of the thumb adductor was associated with a reduction in the TOF ratio in the corrugator supercilii. The similarity between blockades of the corrugator muscle, the diaphragm, and the larynx is of clinical interest.

Bloqueo neuromuscular inducido por neostigmina en el músculo Corrugator supercilii / Neostigmine-induced neuromuscular blockade in the corrugator supercilii muscle

Objetivo: Investigar si una dosis de neostigmina administrada cuando el adductor pollicis presenta dos respuestas al tren de cuatro estímulos (TOF), puede producir una atenuación del cociente del TOF en el músculo corrugator supercilii (CS). Pacientes y métodos: Se diseñó un estudio casos-control con pacientes ASA I-II entre 18 y 65 años. Se utilizaron dos acelerómetros: nervio cubital/músculo aductor del pulgar y nervio facial/músculo CS. El bloqueo neuromuscular se indujo con rocuronio 0,6 mg Kg–1. Cuando el TOF ratio en el aductor del pulgar mostraba tres respuestas se administró neostigmina (40 μg Kg–1). Si en ese momento el TOF ratio en el CS disminuía 10 o más puntos se clasificaba como “caso”. Se midieron las variables edad, sexo, peso, talla, índice de masa corporal (IMC), duración y TOF ratio en el CS cuando se administró neostigmina. Resultados: Se incluyeron 10 casos y 10 controles. No hubo diferencias significativas excepto en el TOF ratio en el CS (media, [DE]): 70,9% (17,8%) en los casos frente a 35,3% (7,8%) en los controles (p < 0,001). Conclusiones: En nuestros pacientes administrar neostigmina tras la aparición de la tercera respuesta al TOF en el aductor del pulgar se asoció con un descenso del TOF ratio en el CS. La similitud del bloqueo del corrugator con el diafragma y la laringe tiene interés sobre la relevancia clínica del fenómeno(AU)

Objective: To investigate whether a single dose of neostigmine, administered when the adductor pollicis muscle presents 2 twitches in train-of-four (TOF) stimulation, can reduce the TOF ratio in the corrugator supercilii muscle. Patients and methods: We designed a case-control study of patients between 18 and 65 years of age classified ASA 1-2. We used 2 accelerometers—1 for the cubital nerve/thumb adductor muscle and 1 for the facial nerve/corrugator supercilii muscle. Neuromuscular blockade was induced with 0.6 mg·kg–1 of rocuronium, and 40 μg·kg–1 of neostigmine was administered at the third twitch in the TOF in the thumb adductor. If the TOF ratio in the corrugator supercilii fell by 10% or more at that time, the patient was classified as a case. We recorded the age, sex, weight, height, body mass index, duration of the procedure, and TOF ratio in the corrugator supercilii muscle when the neostigmine was administered. Results: Ten cases and 10 controls were enrolled. No significant differences between cases and controls were found in any variables except the mean (SD) TOF ratio in the corrugator supercilii muscle: 70.9% (17.8%) in cases and 35.3% (7.8%) in controls (P<.001). Conclusions: In our patients, administration of neostigmine after the appearance of the third twitch in TOF stimulation of the thumb adductor was associated with a reduction in the TOF ratio in the corrugator supercilii. The similarity between blockades of the corrugator muscle, the diaphragm, and the larynx is of clinical interest(AU)