▶ IP injection of
18Ffallypride results in measurable, but variable, striatal uptake. ▶ Drugs that prevent defluorination of
18Ffallypride should improve the striatal signal. ▶ Further ...characterization of IP
18Ffallypride is needed to develop this paradigm for assessing changes in
in vivo dopamine during behavior.
Great progress has been made toward using small animal PET to assess neurochemical changes during behavior.
18Ffallypride (FAL) is a D
2/D
3 antagonist that is sensitive to changes in endogenous dopamine, and, in theory, could be used to assess changes in dopamine during behavioral paradigms. Tail vein injections of tracer require restraint in awake animals, and catheter implantation is invasive and can cause logistical problems. Thus, administering tracer with IP injections (which are well-tolerated by rodents) would be preferable. The purpose of this study was to determine whether IP injection of FAL would produce striatal uptake similar to that seen with traditional IV tail vein injection protocols. Four male Sprague–Dawley rats underwent IP injection of FAL, followed by a 30-min uptake and subsequent dynamic image acquisition on the IndyPET III small animal scanner. Three of these rats also received traditional dynamic scanning with IV FAL injection via a tail vein. Two rats that received IP injection had moderate striatal uptake, with striatum/cerebellum ratios (SUVR) that were only ∼20% lower than ratios from IV scans. Two other rats had little to no uptake; SUVR values were ∼70% lower than IV SUVR. These latter two animals showed heavy bone uptake, evidence of defluorination of FAL. The results of this pilot study suggest that it may be possible to achieve striatal uptake of FAL after IP injection. However, this was not seen consistently across animals. Future studies are needed to validate, and then to optimize, the use of IP FAL for behavioral imaging protocols.
Background Hepatocellular carcinoma (HCC) remains a global health problem with unique diagnostic and therapeutic challenges, including difficulties in identifying the highest risk patients. Previous ...work from our lab has established the murine multidrug resistance-2 mouse (MDR2) model of HCC as a reasonable preclinical model that parallels the changes seen in human inflammatory associated HCC. The purpose of this study is to evaluate modalities of PET/CT in MDR2.sup.-/- mice in order to facilitate therapeutic translational studies from bench to bedside. Methods .sup.18F-FDG and .sup.11C-acetate PET/CT was performed on 12 m MDR2.sup.-/- mice (n = 3/tracer) with HCC and 12 m MDR2.sup.-/+ control mice (n = 3/tracer) without HCC. To compare PET/CT to biological markers of HCC and cellular function, serum alpha-fetoprotein (AFP), lysophosphatidic acid (LPA), cAMP and hepatic tumor necrosis factor alpha (TNFalpha) were quantified in 3-12 m MDR2.sup.-/- (n = 10) mice using commercially available ELISA analysis. To translate results in mice to patients .sup.11C-acetate PET/CT was also performed in 8 patents suspected of HCC recurrence following treatment and currently on the liver transplant wait list. Results Hepatic.sup.18F-FDG metabolism was not significantly increased in MDR2.sup.-/- mice. In contrast, hepatic .sup.11C-acetate metabolism was significantly elevated in MDR2.sup.-/- mice when compared to MDR2.sup.-/+ controls. Serum AFP and LPA levels increased in MDR2.sup.-/- mice contemporaneous with the emergence of HCC. This was accompanied by a significant decrease in serum cAMP levels and an increase in hepatic TNFalpha. In patients suspected of HCC recurrence there were 5 true positives, 2 true negatives and 1 suspected false .sup.11C-acetate negative. Conclusions Hepatic .sup.11C-acetate PET/CT tracks well with HCC in MDR2.sup.-/- mice and patients with underlying liver disease. Consequently .sup.11C-acetate PET/CT is well suited to study 1) HCC emergence/progression in patients and 2) reduce animal numbers required to study new chemotherapeutics in murine models of HCC.
The cornerstone of treatment for advanced ALK-positive lung cancer is sequential therapy with increasingly potent and selective ALK inhibitors. The third-generation ALK inhibitor lorlatinib has ...demonstrated clinical activity in patients who failed previous ALK inhibitors. To define the spectrum of
mutations that confer lorlatinib resistance, we performed accelerated mutagenesis screening of Ba/F3 cells expressing EML4-ALK. Under comparable conditions,
-ethyl-
-nitrosourea (ENU) mutagenesis generated numerous crizotinib-resistant but no lorlatinib-resistant clones harboring single
mutations. In similar screens with EML4-ALK containing single
resistance mutations, numerous lorlatinib-resistant clones emerged harboring compound
mutations. To determine the clinical relevance of these mutations, we analyzed repeat biopsies from lorlatinib-resistant patients. Seven of 20 samples (35%) harbored compound
mutations, including two identified in the ENU screen. Whole-exome sequencing in three cases confirmed the stepwise accumulation of
mutations during sequential treatment. These results suggest that sequential ALK inhibitors can foster the emergence of compound
mutations, identification of which is critical to informing drug design and developing effective therapeutic strategies.
Treatment with sequential first-, second-, and third-generation ALK inhibitors can select for compound
mutations that confer high-level resistance to ALK-targeted therapies. A more efficacious long-term strategy may be up-front treatment with a third-generation ALK inhibitor to prevent the emergence of on-target resistance.
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Leptospirosis, the most widespread zoonotic disease in the world, is broadly understudied in multi-host wildlife systems. Knowledge gaps regarding Leptospira circulation in wildlife, particularly in ...densely populated areas, contribute to frequent misdiagnoses in humans and domestic animals. We assessed Leptospira prevalence levels and risk factors in five target wildlife species across the greater Los Angeles region: striped skunks (Mephitis mephitis), raccoons (Procyon lotor), coyotes (Canis latrans), Virginia opossums (Didelphis virginiana), and fox squirrels (Sciurus niger). We sampled more than 960 individual animals, including over 700 from target species in the greater Los Angeles region, and an additional 266 sampled opportunistically from other California regions and species. In the five target species seroprevalences ranged from 5 to 60%, and infection prevalences ranged from 0.8 to 15.2% in all except fox squirrels (0%). Leptospira phylogenomics and patterns of serologic reactivity suggest that mainland terrestrial wildlife, particularly mesocarnivores, could be the source of repeated observed introductions of Leptospira into local marine and island ecosystems. Overall, we found evidence of widespread Leptospira exposure in wildlife across Los Angeles and surrounding regions. This indicates exposure risk for humans and domestic animals and highlights that this pathogen can circulate endemically in many wildlife species even in densely populated urban areas.
The unprecedented scale of the Ebola outbreak in Western Africa (2014–2015) has prompted an explosion of efforts to understand the transmission dynamics of the virus and to analyze the performance of ...possible containment strategies. Models have focused primarily on the reproductive numbers of the disease that represent the average number of secondary infections produced by a random infectious individual. However, these population-level estimates may conflate important systematic variation in the number of cases generated by infected individuals, particularly found in spatially localized transmission and superspreading events. Although superspreading features prominently in first-hand narratives of Ebola transmission, its dynamics have not been systematically characterized, hindering refinements of future epidemic predictions and explorations of targeted interventions. We used Bayesian model inference to integrate individual-level spatial information with other epidemiological data of community-based (undetected within clinical-care systems) cases and to explicitly infer distribution of the cases generated by each infected individual. Our results show that superspreaders play a key role in sustaining onward transmission of the epidemic, and they are responsible for a significant proportion (∼61%) of the infections. Our results also suggest age as a key demographic predictor for superspreading. We also show that community-based cases may have progressed more rapidly than those notified within clinical-care systems, and most transmission events occurred in a relatively short distance (with median value of 2.51 km). Our results stress the importance of characterizing superspreading of Ebola, enhance our current understanding of its spatiotemporal dynamics, and highlight the potential importance of targeted control measures.
Cancer-associated fibroblasts (CAFs) are highly heterogeneous. With the lack of a comprehensive understanding of CAFs' functional distinctions, it remains unclear how cancer treatments could be ...personalized based on CAFs in a patient's tumor. We have established a living biobank of CAFs derived from biopsies of patients' non-small lung cancer (NSCLC) that encompasses a broad molecular spectrum of CAFs in clinical NSCLC. By functionally interrogating CAF heterogeneity using the same therapeutics received by patients, we identify three functional subtypes: (1) robustly protective of cancers and highly expressing HGF and FGF7; (2) moderately protective of cancers and highly expressing FGF7; and (3) those providing minimal protection. These functional differences among CAFs are governed by their intrinsic TGF-β signaling, which suppresses HGF and FGF7 expression. This CAF functional classification correlates with patients' clinical response to targeted therapies and also associates with the tumor immune microenvironment, therefore providing an avenue to guide personalized treatment.
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•A living biobank of CAFs from NSCLC patients recapitulates clinical CAF heterogeneity•Therapeutic profiling of the NSCLC CAFs reveals three distinctive functional subtypes•Subtype I and II CAFs have high HGF and FGF7 expression and protect cancer cells•Subtype III CAFs associate with better clinical response and immune cell migration
Hu et al. identify that cancer-associated fibroblasts (CAFs) derived from non-small cell lung cancer patients are functionally heterogeneous. These functional distinctions directly impact response to clinical anticancer treatment and associate with the tumor immune microenvironment. Thus, CAF functional heterogeneity defines a unique parameter for designing more personalized treatments.
Mitofusins reside on the outer mitochondrial membrane and regulate mitochondrial fusion, a physiological process that impacts diverse cellular processes. Mitofusins are activated by conformational ...changes and subsequently oligomerize to enable mitochondrial fusion. Here, we identify small molecules that directly increase or inhibit mitofusins activity by modulating mitofusin conformations and oligomerization. We use these small molecules to better understand the role of mitofusins activity in mitochondrial fusion, function, and signaling. We find that mitofusin activation increases, whereas mitofusin inhibition decreases mitochondrial fusion and functionality. Remarkably, mitofusin inhibition also induces minority mitochondrial outer membrane permeabilization followed by sub-lethal caspase-3/7 activation, which in turn induces DNA damage and upregulates DNA damage response genes. In this context, apoptotic death induced by a second mitochondria-derived activator of caspases (SMAC) mimetic is potentiated by mitofusin inhibition. These data provide mechanistic insights into the function and regulation of mitofusins as well as small molecules to pharmacologically target mitofusins.
Variation in genes involved in ethanol metabolism has been shown to influence risk for alcohol dependence (AD) including protective loss of function alleles in ethanol metabolizing genes. We ...therefore hypothesized that people with severe AD would exhibit different patterns of rare functional variation in genes with strong prior evidence for influencing ethanol metabolism and response when compared to genes not meeting these criteria.
Leverage a novel case only design and Whole Exome Sequencing (WES) of severe AD cases from the island of Ireland to quantify differences in functional variation between genes associated with ethanol metabolism and/or response and their matched control genes.
First, three sets of ethanol related genes were identified including those a) involved in alcohol metabolism in humans b) showing altered expression in mouse brain after alcohol exposure, and altering ethanol behavioral responses in invertebrate models. These genes of interest (GOI) sets were matched to control gene sets using multivariate hierarchical clustering of gene-level summary features from gnomAD. Using WES data from 190 individuals with severe AD, GOI were compared to matched control genes using logistic regression to detect aggregate differences in abundance of loss of function, missense, and synonymous variants, respectively.
Three non-independent sets of 10, 117, and 359 genes were queried against control gene sets of 139, 1522, and 3360 matched genes, respectively. Significant differences were not detected in the number of functional variants in the primary set of ethanol-metabolizing genes. In both the mouse expression and invertebrate sets, we observed an increased number of synonymous variants in GOI over matched control genes. Post-hoc simulations showed the estimated effects sizes observed are unlikely to be under-estimated.
The proposed method demonstrates a computationally viable and statistically appropriate approach for genetic analysis of case-only data for hypothesized gene sets supported by empirical evidence.
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