Effect of temperature on pollen tube kinetics and dynamics in sweet cherry, Prunus avium (Rosaceae)

The article is available at: http://www.amjbot.org/cgi/content/full/91/4/558Prevailing ambient temperature during the reproductive phase is one of several important factors for seed and fruit set in different plant species, and its consequences on reproductive success may increase with global warming. The effect of temperature on pollen performance was evaluated in sweet cherry (Prunus avium L.), comparing as pollen donors two cultivars that differ in their adaptation to temperature. ‘Sunburst’ is a cultivar that originated in Canada with a pedigree of cultivars from Northern Europe, while ‘Cristobalina’ is a cultivar native to southeast Spain, adapted to warmer conditions. Temperature effects were tested either in controlled-temperature chambers or in the field in a plastic cage. In both genotypes, an increase in temperature reduced pollen germination, but accelerated pollen tube growth. However, a different genotypic response, which reflected the overall adaptation of the pollen donor, was obtained for pollen tube dynamics, expressed as the census of the microgametophyte population that successfully reached the base of the style. While both cultivars performed similarly at 20°C, the microgametophyte population was reduced at 30°C for Sunburst and at 10°C for Cristobalina. These results indicate a differential genotypic response to temperature during the reproductive phase, which could be important in terms of the time needed for a plant species to adapt to rapid temperature changes.A. H. was supported by an AECI and an SIA-DGA fellowship, and financial support for this work was provided by INIA (project grant RTA 01-103).Peer reviewe

Forgotten electrical accidents and the birth of shockproof X-ray systems

OBJECTIVES: To commemorate victims of electrical accidents that occurred in the first decades of radiology and relate these accidents to the evolution of the X-ray apparatus. METHODS: Digitised newspapers, scientific journals, books and reports of legal procedures were searched for electrical accidents involving X-ray systems. Information on the historical systems was retrieved from the scientific literature and brochures from manufacturers. RESULTS: We found 51 fatal and 62 non-fatal but serious electrical accidents. Most of them occurred between 1920 and 1940 and involved transformers that provided output currents well above the threshold for the induction of ventricular fibrillation. The accidents led to recommendations and regulations to improve safety for operators and patients, and spurred manufacturers to technical developments that culminated in fully electrically shockproof systems by 1935. CONCLUSIONS: Although largely forgotten, the development of the shockproof X-ray systems we take for granted today lasted about 4 decades and was associated with considerable human suffering. The complete solution of the problem is a success story of engineering realised by contributions from all parties involved. MAIN MESSAGES: • The development of electrically shockproof X-ray systems took about 4 decades (1895-1935). • Between 1896 and 1920 electrical shocks from X-ray systems were common, but their consequences limited. • After 1920, transformers killed by delivering currents above the ventricular fibrillation threshold. • Inductors, static generators and high-frequency coils were generally low-current systems and safe. • We found 51 fatal and 62 serious non-fatal electrical accidents, most occurring from 1920 to 1940

Bone metabolic activity in hyperostosis cranialis interna measured with 18F-fluoride PET

F-18-Fluoride PET/CT is a relatively undervalued diagnostic test to measure bone metabolism in bone diseases. Hyperostosis cranialis interna (HCI) is a (hereditary) bone disease characterised by endosteal hyperostosis and osteosclerosis of the skull and the skull base. Bone overgrowth causes entrapment and dysfunction of several cranial nerves. The aim of this study is to compare standardised uptake values (SUVs) at different sites in order to quantify bone metabolism in the affected anatomical regions in HCI patients. Nine affected family members, seven non-affected family members and nine non-HCI non-family members underwent F-18-fluoride PET/CT scans. SUVs were systematically measured in the different regions of interest: frontal bone, sphenoid bone, petrous bone and clivus. Moreover, the average F-18-fluoride uptake in the entire skull was measured by assessing the uptake in axial slides. Visual assessment of the PET scans of affected individuals was performed to discover the process of disturbed bone metabolism in HCI. F-18-Fluoride uptake is statistically significantly higher in the sphenoid bone and clivus regions of affected family members. Visual assessment of the scans of HCI patients is relevant in detecting disease severity and the pattern of disturbed bone metabolism throughout life. F-18-Fluoride PET/CT is useful in quantifying the metabolic activity in HCI and provides information about the process of disturbed bone metabolism in this specific disorder. Limitations are a narrow window between normal and pathological activity and the influence of age. This study emphasises that F-18-fluoride PET/CT may also be a promising diagnostic tool for other metabolic bone disorders, even those with an indolent course

Effect of spinal immobilisation devices on radiation exposure in conventional radiography and computed tomography

Trauma patients at risk for, or suspected of, spinal injury are frequently transported to hospital using full spinal immobilisation. At the emergency department, immobilisation is often maintained until radiological work-up is completed. In this study, we examined how these devices influence radiation exposure and noise, as a proxy for objective image quality. Conventional radiographs (CR) and computer tomography (CT) scans were made using a phantom immobilised on two types of spineboard and a vacuum mattress and using two types of headblocks. Images were compared for radiation transmission and quantitative image noise. In CR, up to 23 % and, in CT, up to 11 % of radiation were blocked by the devices. Without compensation for the decreased transmission, noise increased by up to 16 % in CT, depending on the device used. Removing the headblocks led to a statistically significant improvement in transmission with automatic exposure control (AEC) enabled. Physicians should make an informed decision whether the increased radiation exposure outweighs the risk of missing a clinically significant injury by not making a CR or CT scan. Manufacturers of immobilisation devices should take radiological properties of their devices into account in the development and production process