Browsing by Author "Mitchell, P"

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    Cultural innovation and megafauna interaction in the early settlement of arid Australia
    (Springer, 2016-11-02) Hamm, G; Mitchell, P; Arnold, LJ; Prideaux, GJ; Questiaux, D; Spooner, NA; Levchenko, VA; Foley, EC; Worthy, TH; Stephenson, B; Coulthard, V; Coulthard, C; Wilton, S; Johnston, D
    Elucidating the material culture of early people in arid Australia and the nature of their environmental interactions is essential for understanding the adaptability of populations and the potential causes of megafaunal extinctions 50–40 thousand years ago (ka). Humans colonized the continent by 50 ka1, 2, but an apparent lack of cultural innovations compared to people in Europe and Africa3, 4 has been deemed a barrier to early settlement in the extensive arid zone2, 3. Here we present evidence from Warratyi rock shelter in the southern interior that shows that humans occupied arid Australia by around 49 ka, 10 thousand years (kyr) earlier than previously reported2. The site preserves the only reliably dated, stratified evidence of extinct Australian megafauna5, 6, including the giant marsupial Diprotodon optatum, alongside artefacts more than 46 kyr old. We also report on the earliest-known use of ochre in Australia and Southeast Asia (at or before 49–46 ka), gypsum pigment (40–33 ka), bone tools (40–38 ka), hafted tools (38–35 ka), and backed artefacts (30–24 ka), each up to 10 kyr older than any other known occurrence7, 8. Thus, our evidence shows that people not only settled in the arid interior within a few millennia of entering the continent9, but also developed key technologies much earlier than previously recorded for Australia and Southeast Asia. © 2016, Nature Publishing Group.
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    Synthesis and evaluation of novel radioiodinated nicotinamides for malignant melanoma
    (Elsevier B.V., 2008-10-01) Liu, X; Pham, TQ; Berghofer, PJ; Chapman, J; Greguric, ID; Mitchell, P; Mattner, F; Loc'h, C; Katsifis, A
    Introduction A series of iodonicotinamides based on the melanin-binding iodobenzamide compound N-2-diethylaminoethyl-4-iodobenzamide was prepared and evaluated for the potential imaging and staging of disseminated metastatic melanoma. Methods [123I]Iodonicotinamides were prepared by iododestannylation reactions using no-carrier-added iodine-123 and evaluated in vivo by biodistribution and competition studies and by single photon emission computed tomography (SPECT) imaging in black and albino nude mice bearing B16F0 murine melanotic and A375 human amelanotic melanoma tumours, respectively. Results The iodonicotinamides displayed low-affinity binding for σ1–σ2 receptors (Ki>300 nM). In biodistribution studies in mice, N-(2-(diethylamino)ethyl)-5-[123I]iodonicotinamide ([123I]1) exhibited the fastest and highest uptake of the nicotinamide series in the B16F0 tumour at 1 h (∼8% ID/g), decreasing slowly over time. No uptake was observed in the A375 tumour. Clearance from the animals by urinary excretion was more rapid for N-alkyl-nicotinamides than for piperazinyl derivatives. At 1 h postinjection, the urinary excretion was 66% ID for [123I]1, while the gastrointestinal tract amounted to 17% ID. Haloperidol was unable to reduce the uptake of [123I]1 in pigmented mice, indicating that this uptake was likely due to an interaction with melanin. SPECT imaging of [123I]1 in black mice bearing the B16F0 melanoma indicated that the radioactivity was predominately located in the tumour and eyes. No specific localisation was observed in nude mice bearing A375 amelanotic tumours. Conclusion These findings suggest that [123I]1, which displays high tumour uptake with rapid clearance from the body, could be a promising imaging agent for the detection of melanotic tumours. © 2008 Elsevier Inc.