The processes controlling the morphology of dendrites have been of great interest to a wide range of communities, since they are examples of an out-of-equilibrium pattern forming system, there is a ...clear connection with battery failure processes, and their morphology sets the properties of many metallic alloys. We determine the three-dimensional morphology of free growing metallic dendrites using a novel X-ray tomographic technique that improves the temporal resolution by more than an order of magnitude compared to conventional techniques. These measurements show that the growth morphology of metallic dendrites is surprisingly different from that seen in model systems, the morphology is not self-similar with distance back from the tip, and that this morphology can have an unexpectedly strong influence on solute segregation in castings. These experiments also provide benchmark data that can be used to validate simulations of free dendritic growth.
Abstract Early-life stress has been shown to increase susceptibility to anxiety and substance abuse. Disrupted activity within the anterior insular cortex (AIC) has been shown to play a role in both ...of these disorders. Altered serotonergic processing is implicated in controlling the activity levels of the associated cognitive networks. We therefore investigated changes in both serotonin receptor expression and glutamatergic synaptic activity in the AIC of alcohol-drinking rhesus monkeys. We studied tissues from male rhesus monkeys raised under two conditions: Male rhesus monkeys (1) “mother reared” (MR) by adult females ( n =9) or (2) “Nursery reared” (NR), that is, separated from their mothers and reared as a separate group under surrogate/peer-reared conditions ( n =9). The NR condition represents a long-standing and well-validated nonhuman primate model of early life stress. All monkeys were trained to self-administer ethanol (4% w/v) or an isocaloric maltose–dextrin control solution. Subsets from each rearing condition were then given daily access to ethanol, water, or maltose–dextrin for 12 months. Tissues were collected at necropsy and were further analyzed. Using real time RT-PCR we found that ethanol-naive, NR monkeys had lower AIC levels of 5-HT1A and 5-HT2A receptor mRNA compared with ethanol-naive, MR animals. Although NR monkeys consumed more ethanol over the 12-month period compared with MR animals, both MR and NR animals expressed greater 5-HT1A and 5-HT2A receptor mRNA levels following chronic alcohol self-administration. The interaction between nursery-rearing conditions and alcohol consumption resulted in a significant enhancement of both 5-HT1A and 5-HT2A receptor mRNA levels such that lower expression levels observed in nursery-rearing conditions were not found in the alcohol self-administration group. Using voltage clamp recordings in the whole cell configuration we recorded excitatory postsynaptic currents in both ethanol-naive and chronic self-administration groups of NR and MR monkeys. Both groups that self-administered ethanol showed greater glutamatergic activity within the AIC. This AIC hyperactivity in MR alcohol-consuming monkeys was accompanied by an increased sensitivity to regulation by presynaptic 5-HT1A receptors that was not apparent in the ethanol-naive, MR group. Our data indicate that chronic alcohol consumption leads to greater AIC activity and may indicate a compensatory upregulation of presynaptic 5-HT1A receptors. Our results also indicate that AIC activity may be less effectively regulated by 5-HT in ethanol-naive NR animals than in NR monkeys in response to chronic ethanol self-administration. These data suggest possible mechanisms for increased alcohol seeking and possible addiction potential among young adults who had previously experienced early-life stress that include disruptions in both AIC activity and serotonin system dynamics.
The CXCR4/CXCL12 axis plays an important role in cell locomotion and metastasis in many cancers. In this study, we hypothesized that the CXCR4/CXCL12 axis promotes migration and invasion of canine ...hemangiosarcoma (HSA) cells. Transcriptomic analysis across 12 HSA cell lines and 58 HSA whole tumour tissues identified heterogeneous expression of CXCR4 and CXCL12, which was associated with cell movement. In vitro, CXCL12 promoted calcium mobilization, cell migration and invasion that were directly proportional to surface expression of CXCR4; furthermore, these responses proved sensitive to the CXCR4 antagonist, AMD3100, in HSA cell lines. These results indicate that CXCL12 potentiates migration and invasion of canine HSA cells through CXCR4 signalling. The direct relationship between these responses in HSA cells suggests that the CXCR4/CXCL12 axis contributes to HSA progression.
Background
Sphingosine‐1‐phosphate (S1P) is a key biolipid signaling molecule that regulates cell growth and survival, but it has not been studied in tumors from dogs.
Hypothesis/Objectives
S1P/S1P1 ...signaling will contribute to the progression of hemangiosarcoma (HSA).
Animals
Thirteen spontaneous HSA tissues, 9 HSA cell lines, 8 nonmalignant tissues, including 6 splenic hematomas and 2 livers with vacuolar degeneration, and 1 endothelial cell line derived from a dog with splenic hematoma were used.
Methods
This was a retrospective case series and in vitro study. Samples were obtained as part of medically necessary diagnostic procedures. Microarray, qRT‐PCR, immunohistochemistry, and immunoblotting were performed to examine S1P1 expression. S1P concentrations were measured by high‐performance liquid chromatography/mass spectrometry. S1P signaling was evaluated by intracellular Ca2+ mobilization; proliferation and survival were evaluated using the MTS assay and Annexin V staining.
Results
Canine HSA cells expressed higher levels of S1P1 mRNA than nonmalignant endothelial cells. S1P1 protein was present in HSA tissues and cell lines. HSA cells appeared to produce low levels of S1P, but they selectively consumed S1P from the culture media. Exogenous S1P induced an increase in intracellular calcium as well as increased proliferation and viability of HSA cells. Prolonged treatment with FTY720, an inhibitor of S1P1, decreased S1P1 protein expression and induced apoptosis of HSA cells.
Conclusions and clinical importance
S1P/S1P1 signaling pathway functions to maintain HSA cell viability and proliferation. The data suggest that S1P1 or the S1P pathway in general could be targets for therapeutic intervention for dogs with HSA.
The pathogenesis of canine T-cell lymphoma remains incompletely understood, partly because there are no well-established in-vivo models to study these malignancies. For this study, we generated a ...patient-derived tumour xenograft (PDTX) from a 10-year-old neutered male golden retriever dog with enteropathy-associated intestinal T-cell lymphoma, large cell type. One of two female, 15-week-old beige/nude/XID mice developed a visible tumour 7 weeks after sections of tumour material from the spleen were surgically implanted. The histological appearance, immunophenotype and clonal antigen receptor rearrangements of the tumour from the recipient mouse showed that it was derived from the primary canine tumour. Our results indicate that immunodeficient mice are receptive hosts to develop in-vivo PDTX models to study the pathogenesis and management of canine T-cell lymphomas.
Canine hemangiosarcoma is a rapidly progressive disease that is poorly responsive to conventional chemotherapy. Despite numerous attempts to advance treatment options and improve outcomes, drug ...resistance remains a hurdle to successful therapy. To address this problem, we used recently characterized progenitor cell populations derived from canine hemangiosarcoma cell lines and grown as non‐adherent spheres to identify potential drug resistance mechanisms as well as drug‐resistant cell populations. Cells from sphere‐forming cultures displayed enhanced resistance to chemotherapy drugs, expansion of dye‐excluding side populations and altered ATP‐binding cassette (ABC) transporter expression. Invasion studies demonstrated variability between cell lines as well as between sphere and monolayer cell populations. Collectively, our results suggest that sphere cell populations contain distinct subpopulations of drug‐resistant cells that utilize multiple mechanisms to evade cytotoxic drugs. Our approach represents a new tool for the study of drug resistance in hemangiosarcoma, which could alter approaches for treating this disease.
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