Dasatinib Reduces Lung Inflammation and Fibrosis in Acute Experimental Silicosis

Silicosis is an occupational lung disease with no effective treatment. We hypothesized that dasatinib, a tyrosine kinase inhibitor, might exhibit therapeutic efficacy in silica-induced pulmonary fibrosis. Silicosis was induced in C57BL/6 mice by a single intratracheal administration of silica particles, whereas the control group received saline. After 14 days, when the disease was already established, animals were randomly assigned to receive DMSO or dasatinib (1 mg/kg) by oral gavage, twice daily, for 14 days. On day 28, lung morphofunction, inflammation, and remodeling were investigated. RAW 264.7 cells (a macrophage cell line) were incubated with silica particles, followed by treatment or not with dasatinib, and evaluated for macrophage polarization. On day 28, dasatinib improved lung mechanics, increased M2 macrophage counts in lung parenchyma and granuloma, and was associated with reduction of fraction area of granuloma, fraction area of collapsed alveoli, protein levels of tumor necrosis factor-α, interleukin-1β, transforming growth factor-β, and reduced neutrophils, M1 macrophages, and collagen fiber content in lung tissue and granuloma in silicotic animals. Additionally, dasatinib reduced expression of iNOS and increased expression of arginase and metalloproteinase-9 in silicotic macrophages. Dasatinib was effective at inducing macrophage polarization toward the M2 phenotype and reducing lung inflammation and fibrosis, thus improving lung mechanics in a murine model of acute silicosis.     

Ecophysiology and distribution of the endemic leafless spurgeEuphorbia aphylla and the introducedE. tirucalli (Euphorbiaceae,Euphorbia sect.Tirucalli) in the Canary Islands

The leafless spurgeEuphorbia aphylla (Euphorbiaceae), an endemic species restricted to several of the Canary Islands where it inhabits coastal and arid localities, expresses Crassulacean Acid Metabolism (CAM) when it is subjected to summer drought. A flexible CAM is consistent with the general ecology of the species. It is the only member of sect.Tirucalli native to the Canary Islands and is at the north-western edge of the section's biogeographical range. The other members of the section have a paleotropic distribution and are found throughout Africa. Many of them are regarded as obligate CAM plants, includingE. tirucalli which was used as a comparison in ecophysiological experiments examining the response ofE. aphylla to drought and temperature.     

Structure-activity relationships for unsaturated dialdehydes. 6. The mutagenic activity of 11 compounds in the V79/HGPRT assay.

The mutagenic activity of 11 sesquiterpenoid unsaturated dialdehydes in the V79/HGPRT assay has been determined, and is compared with previously published data on the mutagenicity of the same compounds towards Ames Salmonella strains. One compound, isovelleral, is a potent mutagen in both assays, while six compounds, which are positive in the Ames Salmonella/microsome assay, show no significant activity in this study. One compound, acetylmerulidial, is negative in the Ames Salmonella/microsome assay but significantly although weakly mutagenic in the V79/HGPRT assay. The remaining three compounds are inactive in both assays. The study is part of a general investigation of quantitative structure-activity relationships for unsaturated dialdehydes, a class of natural occurring compounds known for their potent and numerous biological activities.     

Oscillatory burst discharge generated through conditional backpropagation of dendritic spikes.

Gamma frequencies of burst discharge (>40 Hz) have become recognized in select cortical and non-cortical regions as being important in feature extraction, neural synchrony and oscillatory discharge. Pyramidal cells of the electrosensory lateral line lobe (ELL) of Apteronotus leptorhynchus generate burst discharge in relation to specific features of sensory input in vivo that resemble those recognized as gamma frequency discharge when examined in vitro. We have shown that these bursts are generated by an entirely novel mechanism termed conditional backpropagation that involves an intermittent failure of dendritic Na+ spike conduction. Conditional backpropagation arises from a frequency-dependent broadening of dendritic spikes during repetitive discharge, and a mismatch between the refractory periods of somatic and dendritic spikes. A high threshold class of K+ channel, AptKv3.3, is expressed at high levels and distributed over the entire soma-dendritic axis of pyramidal cells. AptKv3.3 channels are shown to contribute to the repolarization of both somatic and dendritic spikes, with pharmacological blockade of dendritic Kv3 channels revealing an important role in controlling the threshold for burst discharge. The entire process of conditional back-propagation and burst output is successfully simulated using a new compartmental model of pyramidal cells that incorporates a cumulative inactivation of dendritic K+ channels during repetitive discharge. This work is important in demonstrating how the success of spike backpropagation can control the output of a principle sensory neuron, and how this process is regulated by the distribution and properties of voltage-dependent K+ channels.     

Hydroxytyrosol glucuronides protect renal tubular epithelial cells against H(2)O(2) induced oxidative damage

Hydroxytyrosol (2-(3′,4′-dihydroxyphenyl)ethanol; HT), the most active ortho-diphenolic compound, present either in free or esterified form in extravirgin olive oil, is extensively metabolized in vivo mainly to O-methylated, O-sulfated and glucuronide metabolites. We investigated the capacity of three glucuronide metabolites of HT, 3′-O-β-d-glucuronide and 4′-O-β-d-glucuronide derivatives and 2-(3′,4′-dihydroxyphenyl)ethanol-1-O-β-d-glucuronide, in comparison with the parent compound, to inhibit H₂O₂ induced oxidative damage and cell death in LLC-PK1 cells, a porcine kidney epithelial cell line. H₂O₂ treatment exerted a toxic effect inducing cell death, interacting selectively within the pro-death extracellular-signal relate kinase (ERK 1/2) and the pro-survival Akt/PKB signaling pathways. It also produced direct oxidative damage initiating the membrane lipid peroxidation process. None of the tested glucuronides exhibited any protection against the loss in renal cell viability. They also failed to prevent the changes in the phosphorylation states of ERK and Akt, probably reflecting their inability to enter the cells, while HT was highly effective. Notably, pretreatment with glucuronides exerted a protective effect at the highest concentration tested against membrane oxidative damage, comparable to that of HT: the formation of malondialdehyde, fatty acid hydroperoxides and 7-ketocholesterol was significantly inhibited.     

Elicitation of different Panax ginseng transformed root phenotypes for an improved ginsenoside production

We tested the effect of the presence in the culture medium of chitosan, vanadyl sulfate or methyl jasmonate on growth and ginsenoside production of three stable hairy root lines of Panax ginseng C.A. Meyer showing different morphological phenotypes C-M, HR-M and T-M. The response depended upon line phenotype, specificity of the elicitor and the stage of growth at which the lines were treated. The highest ginsenoside yield was found when methyl jasmonate was added during the progressive deceleration growth phase (on day 25 of culture). In this case, the ginsenoside content reached at the end of the culture (day 28) by root lines C-M, HR-M and T-M was, respectively, 2, 1.8 and 4 times higher than the highest content achieved, also at the end of the culture, by the corresponding untreated root lines. Under the same conditions, the ginsenoside content in the presence of vanadyl sulfate also increased considerably, while with chitosan it clearly decreased. The ginsenoside pattern in response to the presence of the elicitors is also considered.     

Intestinal Methanobrevibacter smithii but not total bacteria is related to diet‐induced weight gain in rats

It is increasingly understood that gastrointestinal (GI) methanogens, including Methanobrevibacter smithii, influence host metabolism.

Objective:

Therefore, we compared M. smithii colonization and weight gain in a rat model under different dietary conditions.

Design and Methods:

Sprague‐Dawley rats were inoculated with M. smithii or vehicle (N = 10/group), fed normal chow until day 112 postinoculation, high‐fat chow until day 182, then normal chow until day 253. Thereafter, five rats from each group were fed high‐fat and normal chow until euthanasia.

Results:

Both groups exhibited M. smithii colonization, which increased following inoculation only for the first 9 days. Change to high‐fat chow correlated with significant increases in weight (P < 0.00001) and stool M. smithii (P < 0.01) in all rats, with stool M. smithi decreasing on return to normal chow. Rats switched back to high‐fat on day 253 further increased weight (P < 0.001) and stool M. smithii (P = 0.039). Euthanasia revealed all animals had higher M. smithii, but not total bacteria, in the small intestine than in the colon. Rats switched back to high‐fat chow had higher M. smithii levels in the duodenum, ileum, and cecum than those fed normal chow; total bacteria did not differ in any bowel segment. Rats which gained more weight had more bowel segments colonized, and the lowest weight recorded was in a rat on high‐fat chow which had minimal M. smithii colonization.

Conclusions:

We conclude that M. smithii colonization occurs in the small bowel as well as in the colon, and that the level and extent of M. smithii colonization is predictive of degree of weight gain in this animal model.     

The Attentional Set Shifting Task: A Measure of Cognitive Flexibility in Mice

Cognitive impairment, particularly involving dysfunction of circuitry within the prefrontal cortex (PFC), represents a core feature of many neuropsychiatric and neurodevelopmental disorders, including depression, post-traumatic stress disorder, schizophrenia and autism spectrum disorder. Deficits in cognitive function also represent the most difficult symptom domain to successfully treat, as serotonin reuptake inhibitors and tricyclic antidepressants have only modest effects. Functional neuroimaging studies and postmortem analysis of human brain tissue implicate the PFC as being a primary region of dysregulation in patients with these disorders. However, preclinical behavioral assays used to assess these deficits in mouse models which can be readily manipulated genetically and could provide the basis for studies of new treatment avenues have been underutilized. Here we describe the adaptation of a behavioral assay, the attentional set shifting task (AST), to be performed in mice to assess prefrontal cortex mediated cognitive deficits. The neural circuits underlying behavior during the AST are highly conserved across humans, nonhuman primates and rodents, providing excellent face, construct and predictive validity.     

Intracellular distribution of lysosomal sialidase is controlled by the internalization signal in its cytoplasmic tail

Sialidase (neuraminidase), encoded by the neu-1 gene in the major histocompatibility complex locus catalyzes the intralysosomal degradation of sialylated glycoconjugates. Inherited deficiency of sialidase results in sialidosis or galactosialidosis, both severe metabolic disorders associated with lysosomal storage of oligosaccharides and glycopeptides. Sialidase also plays an important role in cellular signaling and is specifically required for the production of cytokine interleukin-4 by activated T lymphocytes. In these cells, neu-1-encoded sialidase activity is increased on the cell surface, suggesting that a specific mechanism regulates sorting of this enzyme to the plasma membrane. We investigated that mechanism by first showing that sialidase contains the internalization signal found in lysosomal membrane proteins targeted to endosomes via clathrin-coated pits. The signal consists of a C-terminal tetrapeptide (412)YGTL(415), with Tyr(412) and Leu(415) essential for endocytosis of the enzyme. We further demonstrated that redistribution of sialidase from lysosomes to the cell surface of activated lymphocytes is accompanied by increased reactivity of the enzyme with anti-phosphotyrosine antibodies. We speculate that phosphorylation of Tyr(412) results in inhibition of sialidase internalization in activated lymphocytes.