On the Usage of Recalibrated Radiance in Reanalysis Experiments

Usage of re-calibrated data in reanalysis systems are quite common due to their uniform and continuous data distribution. Recalibrated radiosonde temperature and SSU radiances have already shown positive impact in MERRA and MERRA2 reanalyses. In this study recalibrated AMSU-A radiances are used to study sudden degradation of observation statistics which are noticed with the introduction of new AMSU-A radiances in MERRA2. In particular, the analysis temperature in the upper stratosphere showed large variability due to lack of viable observation at that height in the atmosphere. Our results show that the re-calibrated AMSU-A radiance in a system similar to MERRA2 is capable of mitigating the problem

Behavioral Characterization of GCLM-Knockout Mice, a Model for Enhanced Susceptibility to Oxidative Stress

Glutathione (GSH) is a major player in cellular defense against oxidative stress. Deletion of the modifier subunit of glutamate cysteine ligase (GCLM), the first and the rate-limiting enzyme in the synthesis of GSH, leads to significantly lower GSH levels in all tissues including the brain. GCLM-knockout (Gclm−/−) mice may thus represent a model for compromised response to oxidative stress amenable to in vitro and in vivo investigations. In order to determine whether the diminished GSH content would by itself cause behavioral alterations, a series of behavioral tests were carried out comparing young adult Gclm−/− with wild-type mice. Tests included the rotarod, acoustic startle reflex and prepulse inhibition of the startle reflex, open field behavior, and the platform reversal variant of the Morris Water Maze. Results showed no differences between Gclm−/− and wild-type mice in any of the neurobehavioral tests. However, more subtle alterations, or changes which may appear as animals age, cannot be excluded

Retinoic acid and IFNγ induce parallel <i>Arg1</i> and <i>Nos2</i> gene expression in primary mouse Kupffer cells.

Abstract Acute inflammation is associated with classically activated macrophages, while chronic inflammation is associated with fibrosis and alternatively activated (M2) macrophages. Liver fibrosis is a common complication of chronic liver inflammation, yet the molecular signals that promote M2 Kupffer cells, resident liver macrophages, are poorly defined. In the liver, activated hepatic stellate cells (HSC) are associated with fibrosis and release retinoic acid (RA). Here, we test the hypothesis that RA polarizes Kupffer cells to an M2 state. We contrast this to activation by IFNγ or lipopolysaccharide (LPS). Kupffer cells were isolated from C57BL/6J mice (N = 2–5) by sort-purification; plated at 30,000 per well for 24 hours; and then stimulated with 100 ng/mL LPS, 100 ng/mL IFNγ, 100 μM RA, or IFNγ + RA for 24 hours. Isolated RNA was analyzed by microfluidic qRT-PCR using assays for genes characteristic of macrophage activation. LPS induced Socs3, Ptgs2, Nos2, Tnf, Icam1, Il6, Il1a, Il10, and Marco. IFNγ induced Socs3, Ptgs2, Nos2, Tnf, Icam1, Ciita, Ccl12, and Klf4; and suppressed Mrc1. RA only induced expression of Arginase-1 (Arg1). Unexpectedly, co-treatment with RA and IFNγ induced additive expression. In summary, treatment of primary Kupffer cells with RA induces Arg1; co-treatment with IFNγ and RA simultaneously induces Arg1 and Nos2; and LPS, but not IFNγ, induces Il6 gene expression. These results support the hypothesis that HSC activation may induce aspects of alternative activation in Kupffer cells and demonstrate that classical and alternative activation fates of macrophages are not always mutually exclusive.</jats:p

Assessing Sensitivity of MERRA-2 to AMSU-A in the Upper Stratosphere

AbstractMicrowave temperature sounders provide key observations in data assimilation, both in the current and historical global observing systems, as they provide the largest amount of horizontal and vertical temperature information due to their insensitivity to clouds. In the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), microwave sounder radiances from the Advanced Microwave Sounding Unit-A (AMSU-A) are assimilated beginning with NOAA-15 and continuing through the current period. The time series of observation minus background statistics for AMSU-A channels sensitive to the upper stratosphere and lower mesosphere show variabilities due to changes in the AMSU-A constellation in the early AMSU-A period. Noted discrepancies are seen at the onset and exit of AMSU-A observations on the NOAA-15, NOAA-16, NOAA-17, and NASA EOS Aqua satellites. This effort characterizes the sensitivity, both in terms of the observations and the MERRA-2 data. Furthermore, it explores the use of reprocessed and intercalibrated datasets to evaluate whether these homogenized observations can reduce the disparity due to change in instrumental biases against the model background. The results indicate that the AMSU-A radiances used in MERRA-2 are the fundamental cause of this interplatform sensitivity, which can be mitigated by using reprocessed data. The results explore the importance of the reprocessing of the AMSU-A radiances as well as their intercalibration.</jats:p

Cross-presentation of antigen by diverse subsets of murine liver cells

Antigen cross-presentation is a principal function of specialized antigen-presenting cells of bone marrow origin such as dendritic cells. While these cells are sometimes known as “professional” antigen-presenting cells, non-bone marrow derived cells may also act as antigen-presenting cells. Here, using four-way liver cell isolation and parallel comparison of candidate antigen presenting cells, we show that depending on the abundance of antigen-donor cells, different subsets of liver cells could cross-present a hepatocyte-associated antigen. This function was observed in both liver sinusoidal endothelial cells and Kupffer cells even at very low antigen concentration, as well as when using soluble protein. Antigen cross-presentation by liver cells induced efficient CD8+ T cell proliferation in a similar manner to classical dendritic cells from spleen. However, proliferated cells expressed lower level of T-cell activation markers and intracellular interferon-gamma levels. In contrast to classical spleen dendritic cells, cross-presentation by liver antigen presenting cells was predominantly dependent on Intercellular Adhesion Molecule-1. CONCLUSION: Hepatic sinusoids are an environment rich in antigen cross-presenting activity. However the liver's resident antigen-presenting cells cause partial T-cell activation. These results clarify how the liver can act as a primary site of CD8+ T-cell activation, and why immunity against hepatocyte pathogens is sometimes ineffectiv

Hepatocyte death induces TRIF-mediated sterile inflammation in the liver

Abstract Hepatocyte death occurs as a result of infection, such as with hepatitis B and C viruses, and as a result of non-pathogen insults, such as chronic alcohol abuse, ischemia reperfusion injury, and acetaminophen overdose. The manner in which liver-specific cell populations—hepatocytes, resident macrophage Kupffer cells (KCs), and liver sinusoidal endothelial cells (LSECs)—respond to this death is critical to understand as the resulting immune response often results not in resolution, but in enhanced liver inflammation that can ultimately lead to fibrosis and cirrhosis. Using an adeno-associated virus vector (AAV) encoding the human diphtheria toxin receptor (hDTR), we have created a murine model of hepatocyte-specific death. After administration of diphtheria toxin (DT), we see peak liver damage at 48 hours, as measured by serum alanine aminotransferase (ALT) levels. This response is largely controlled by TIR-domain-containing adapter-inducing interferon-β (TRIF), independent of both Toll-like receptor 4 (TLR4) and Interferon alpha/beta receptor (IFNAR), and is characterized by the up-regulation of Ifn-beta in hepatocytes by 24 hours and the up-regulation of both monocyte- and neutrophil-recruiting chemokines from hepatocytes, LSECs, and KCs most strongly by 48 hours. We see TRIF-dependent up-regulation of adhesion molecules (Vcam1 and Icam1) on hepatocytes and LSECs and down-regulation of MHC-II on the surface of KCs. Understanding how the TRIF pathway controls responses to hepatocyte death provides an intriguing counterpoint when compared to other models of liver death—such as nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, and ischemia reperfusion injury—which occur via MyD88-dependent routes.</jats:p

Glutamate Cysteine Ligase Modifier Subunit (Gclm) Null Mice Have Increased Ovarian Oxidative Stress and Accelerated Age-Related Ovarian Failure.

Glutathione (GSH) is the one of the most abundant intracellular antioxidants. Mice lacking the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in GSH synthesis, have decreased GSH. Our prior work showed that GSH plays antiapoptotic roles in ovarian follicles. We hypothesized that Gclm(-/-) mice have accelerated ovarian aging due to ovarian oxidative stress. We found significantly decreased ovarian GSH concentrations and oxidized GSH/oxidized glutathione redox potential in Gclm(-/-) vs Gclm(+/+) ovaries. Prepubertal Gclm(-/-) and Gclm(+/+) mice had similar numbers of ovarian follicles, and as expected, the total number of ovarian follicles declined with age in both genotypes. However, the rate of decline in follicles was significantly more rapid in Gclm(-/-) mice, and this was driven by accelerated declines in primordial follicles, which constitute the ovarian reserve. We found significantly increased 4-hydroxynonenal immunostaining (oxidative lipid damage marker) and significantly increased nitrotyrosine immunostaining (oxidative protein damage marker) in prepubertal and adult Gclm(-/-) ovaries compared with controls. The percentage of small ovarian follicles with increased granulosa cell proliferation was significantly higher in prepubertal and 2-month-old Gclm(-/-) vs Gclm(+/+) ovaries, indicating accelerated recruitment of primordial follicles into the growing pool. The percentages of growing follicles with apoptotic granulosa cells were increased in young adult ovaries. Our results demonstrate increased ovarian oxidative stress and oxidative damage in young Gclm(-/-) mice, associated with an accelerated decline in ovarian follicles that appears to be mediated by increased recruitment of follicles into the growing pool, followed by apoptosis at later stages of follicular development

Proteomic Analysis of Acetaminophen-Induced Changes in Mitochondrial Protein Expression Using Spectral Counting

Comparative proteomic analysis following treatment with acetaminophen (APAP) was performed on two different models of APAP-mediated hepatocellular injury in order to both identify common targets for adduct formation and track drug-induced changes in protein expression. Male C57BL/6 mice were used as a model for APAP-mediated liver injury in vivo, and TAMH cells were used as a model for APAP-mediated cytotoxicity in vitro. SEQUEST was unable to identify the precise location of sites of adduction following treatment with APAP in either system. However, semiquantitative analysis of the proteomic data sets using spectral counting revealed a downregulation of P450 isoforms associated with APAP bioactivation and an upregulation of proteins related to the electron transport chain by APAP compared to the control. Both mechanisms are likely compensatory in nature as decreased P450 expression is likely to attenuate toxicity associated with N-acetyl-p-quinoneimine (NAPQI) formation, whereas APAP-induced electron transport chain component upregulation may be an attempt to promote cellular bioenergetics