Abstract TP109: Developing Novel Portable Neuroimaging To Deliver Urgent Prehospital Stroke Care

Introduction: Patients with stroke in rural and remote areas have limited access to time-critical stroke care and have worse outcomes. Mobile stroke units (MSUs) are increasingly used worldwide to deliver prehospital stroke care, improving treatment times. However, current brain scanners are too large, heavy, and costly to be used in standard ambulances to access rural regions. The Micro-X solution is a fixed gantry computed tomography (CT) device, using unique cold-cathode technology, in which microscopic carbon nanotubes emit electrons instantaneously when voltage is applied, without heat production, instead of the heated tungsten filament used in conventional CT. This novel technology reduces size and weight, enabling development of a novel CT scanner weighing under 50 kg, a ten-fold reduction compared to the scanner currently used in most MSUs.

Methods: In partnership with the Australian Stroke Alliance, Micro-X is developing a novel lightweight brain scanner for use in ambulances. Based on data from an early prototype cadaver study, we are undertaking further validation studies, including a two-part preclinical study: (1) phantom study using 4 phantoms (CATphan, anthropomorphic, Jaszczak SPECT, and Nuclear Medicine); and (2) subsequent cadaver study, scanning cadavers within 24h of death, compared to standard CT.

Results: The early prototype cadaver study demonstrated feasibility, including identification of lateral and third ventricles when compared to concurrent CT. Through technical improvements in hardware and software, including improved scanner geometry and algorithm development, the planned phantom study will provide data on contrast resolution, quantitative spatial resolution, identification of anatomical structures, and haemorrhage detection compared with conventional CT. The subsequent cadaver study will provide further validation on anatomy identification and artifact reduction and ensure whole-brain coverage.

Conclusion: Preclinical evaluation of this novel lightweight technology compared with conventional CT will provide technical assessment and image validation. This will provide diagnostic confidence to perform pilot in-vivo studies, with the potential to revolutionise prehospital stroke care.

Sexual selection drives the evolution of male wing interference patterns

The seemingly transparent wings of many insects have recently been found to display unexpected structural coloration. These structural colours (wing interference patterns: WIPs) may be involved in species recognition and mate choice, yet little is known about the evolutionary processes that shape them. Furthermore, to date investigations of WIPs have not fully considered how they are actually perceived by the viewers' colour vision. Here, we use multispectral digital imaging and a model of Drosophila vision to compare WIPs of male and female Drosophila simulans from replicate populations forced to evolve with or without sexual selection for 68 generations. We show that WIPs modelled in Drosophila vision evolve in response to sexual selection and provide evidence that WIPs correlate with male sexual attractiveness. These findings add a new element to the otherwise well-described Drosophila courtship display and confirm that wing colours evolve through sexual selection.

Winter is coming: hibernation reverses the outcome of sperm competition in a fly

Sperm commonly compete within females to fertilize ova, but research has focused on short‐term sperm storage: sperm that are maintained in a female for only a few days or weeks before use. In nature, females of many species store sperm for months or years, often during periods of environmental stress, such as cold winters. Here we examine the outcome of sperm competition in the fruit fly Drosophila pseudoobscura, simulating the conditions in which females survive winter. We mated females to two males and then stored the female for up to 120 days at 4°C. We found that the outcome of sperm competition was consistent when sperm from two males was stored for 0, 1 or 30 days, with the last male to mate fathering most of the offspring. However, when females were stored in the cold for 120 days, the last male to mate fathered less than 5% of the offspring. Moreover, when sperm were stored long term the first male fathered almost all offspring even when he carried a meiotic driving sex chromosome that drastically reduces sperm competitive success under short‐term storage conditions. This suggests that long‐term sperm storage can radically alter the outcome of sperm competition.