Baxter, G. | bioRxiv Science

bioRxiv2021

Sodium accumulation in breast cancer predicts malignancy and treatment response

Breast cancer is the leading cause of cancer-related death in women worldwide. Development of novel noninvasive diagnostic and predictive pathophysiological biomarkers would represent a significant clinical improvement. Here, we explored the utility of non-invasive 23Na MRI to profile tumour physiology using preclinical mouse models of breast cancer. We establish that tissue Na+ concentration ([Na+]) is elevated vs non-tumour regions across multiple different tumour models. Ex vivo SBFI fluorescence imaging corroborated that this elevation in tumour [Na+] is due to increased intracellular [Na+]. Effective treatment with cytotoxic chemotherapy reduced tumour tissue [Na+], but was not detected by 1H diffusion-weighted imaging (DWI). Moreover, combining 23Na MRI and DWI measurements enabled superior classification accuracy of tumour vs non-tumour regions compared to either parameter alone. Quantification of breast tumour tissue [Na+] using 23Na MRI thus represents a novel, accurate, non-invasive diagnostic and predictive imaging biomarker.

cancer biology↗

bioRxiv2020

Behaviour of two species of psittacine birds, Crimson Rosella Platycercus elegans and Australian King-Parrot Alisterus scapularis, at wild bird feeding sites in Australia

This study investigated how Crimson Rosellas Platycercus elegans (CR) and Australian King-Parrots Alisterus scapularis (AKP) used provisioned seed at two public bird feeding sites in Australia. A total of 197 CR and 72 AKP were trapped and colour-banded. Observational data was collected every 10mins between 08:00-16:00 for three consecutive days during autumn and spring. Foraging effort was described using five metrics that quantified the birds visiting frequency and foraging duration over each day and observation period. Seed selection (over 5mins) and intake (over 10mins) were determined, and the energy intake was calculated. Total counts and population estimates were calculated for each species. Individual, species, seasonal and geographic variation in the use of provisioned seed was demonstrated by the metric summaries and Restricted Maximum Likelihood Modelling. Both species fed as part of large mixed species flocks that would not naturally congregate together to forage. Overall, CR were found to have higher foraging effort and feed in greater numbers than AKP, but a spectrum of use was observed for both species. Individuals were observed using the provisioned seed between 0-3 days/observation period. When birds used the provisioned seed, they were found to make between 1-8 visits/day, with most lasting 10-30mins. Few daily durations lasted longer than 50mins. Within a 10-minute interval, it was possible for a CR and AKP to obtain between 1.73-62.91% and 6.84-88.54% of their daily energy requirements, respectively. In a visit, either species could fill their crop and meet most, if not all, of their daily energy requirements. A small percentage of birds (6.5%) were found to use the feeding sites daily and for long durations (up to 160mins). It is likely that a proportion of the birds using the provisioned seed at both sites were dependent on the food source and would be at risk if the seed supply were suddenly reduced. The study also provided evidence that wild bird feeding provided an advantage to one or more species, as well as evidence that the food source did not affect the study species seasonal dispersal patterns or juveniles ability to forage on natural food sources.

ecology↗