2,012 research outputs found
Microdissected "cuboids" for microfluidic drug testing of intact tissues
As preclinical animal tests often do not accurately predict drug effects later observed in humans, most drugs under development fail to reach the market. Thus there is a critical need for functional drug testing platforms that use human, intact tissues to complement animal studies. To enable future multiplexed delivery of many drugs to one small biopsy, we have developed a multi-well microfluidic platform that selectively treats cuboidal-shaped microdissected tissues or “cuboids” with well-preserved tissue microenvironments. We create large numbers of uniformly-sized cuboids by semi-automated sectioning of tissue with a commercially available tissue chopper. Here we demonstrate the microdissection method on normal mouse liver, which we characterize with quantitative 3D imaging, and on human glioma xenograft tumors, which we evaluate after time in culture for viability and preservation of the microenvironment. The benefits of size uniformity include lower heterogeneity in future biological assays as well as facilitation of their physical manipulation by automation. Our prototype platform consists of a microfluidic circuit whose hydrodynamic traps immobilize the live cuboids in arrays at the bottom of a multi-well plate. Fluid dynamics simulations enabled the rapid evaluation of design alternatives and operational parameters. We demonstrate the proof-of-concept application of model soluble compounds such as dyes (CellTracker, Hoechst) and the cancer drug cisplatin. Upscaling of the microfluidic platform and microdissection method to larger arrays and numbers of cuboids could lead to direct testing of human tissues at high throughput, and thus could have a significant impact on drug discovery and personalized medicine.The National Cancer Institute; Juno Therapeutics; CoMotion at the University of Washington; a Hong Kong Research Grant Council; an International Scholars award from the Consejo Nacional de Ciencia y Tecnología of Mexico; a Department of Defense Prostate Cancer Research Program and the National Science Foundation Graduate Research Fellowship Program.http://pubs.rsc.org/en/Journals/JournalIssues/LChj2022Mechanical and Aeronautical Engineerin
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
Global extent and drivers of mammal population declines in protected areas under illegal hunting pressure
Illegal hunting is a persistent problem in many protected areas, but an overview of the extent of this problem and its impact on wildlife is lacking. We reviewed 40 years (1980–2020) of global research to examine the spatial distribution of research and socio-ecological factors influencing population decline within protected areas under illegal hunting pressure. From 81 papers reporting 988 species/site combinations, 294 mammal species were reported to have been illegally hunted from 155 protected areas across 48 countries. Research in illegal hunting has increased substantially during the review period and showed biases towards strictly protected areas and the African continent. Population declines were most frequent in countries with a low human development index, particularly in strict protected areas and for species with a body mass over 100 kg. Our results provide evidence that illegal hunting is most likely to cause declines of large-bodied species in protected areas of resource-poor countries regardless of protected area conservation status. Given the growing pressures of illegal hunting, increased investments in people’s development and additional conservation efforts such as improving anti-poaching strategies and conservation resources in terms of improving funding and personnel directed at this problem are a growing priority
Design of Leucine-Rich Repeat Kinase 2 (LRRK2) Inhibitors Using a Crystallographic Surrogate Derived from Checkpoint Kinase 1 (CHK1)
Mutations in leucine-rich repeat
kinase 2 (LRRK2), such as G2019S,
are associated with an increased risk of developing Parkinson’s
disease. Surrogates for the LRRK2 kinase domain based on checkpoint
kinase 1 (CHK1) mutants were designed, expressed in insect cells infected
with baculovirus, purified, and crystallized. X-ray structures of
the surrogates complexed with known LRRK2 inhibitors rationalized
compound potency and selectivity. The CHK1 10-point mutant was preferred,
following assessment of surrogate binding affinity with LRRK2 inhibitors.
Fragment hit-derived arylpyrrolo[2,3-<i>b</i>]pyridine
LRRK2 inhibitors underwent structure-guided optimization using this
crystallographic surrogate. LRRK2-pSer935 HEK293 IC<sub>50</sub> data
for <b>22</b> were consistent with binding to Ala2016 in LRRK2
(equivalent to Ala147 in CHK1 10-point mutant structure). Compound <b>22</b> was shown to be potent, moderately selective, orally available,
and brain-penetrant in wild-type mice, and confirmation of target
engagement was demonstrated, with LRRK2-pSer935 IC<sub>50</sub> values
for <b>22</b> in mouse brain and kidney being 1.3 and 5 nM,
respectively
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