NADPH oxidase-mediated redox signal contributes to lipoteichoic acid-induced MMP-9 upregulation in brain astrocytes

<p>Abstract</p> <p>Background</p> <p>Lipoteichoic acid (LTA) is a component of gram-positive bacterial cell walls and may be elevated in the cerebrospinal fluid of patients suffering from meningitis. Among matrix metalloproteinases (MMPs), MMP-9 has been observed in patients with brain inflammatory diseases and may contribute to the pathology of brain diseases. Moreover, several studies have suggested that increased oxidative stress is implicated in the pathogenesis of brain inflammation and injury. However, the molecular mechanisms underlying LTA-induced redox signal and MMP-9 expression in brain astrocytes remain unclear.</p> <p>Objective</p> <p>Herein we explored whether LTA-induced MMP-9 expression was mediated through redox signals in rat brain astrocytes (RBA-1 cells).</p> <p>Methods</p> <p>Upregulation of MMP-9 by LTA was evaluated by zymographic and RT-PCR analyses. Next, the MMP-9 regulatory pathways were investigated by pretreatment with pharmacological inhibitors or transfection with small interfering RNAs (siRNAs), Western blotting, and chromatin immunoprecipitation (ChIP)-PCR and promoter activity reporter assays. Moreover, we determined the cell functional changes by migration assay.</p> <p>Results</p> <p>These results showed that LTA induced MMP-9 expression via a PKC(α)-dependent pathway. We further demonstrated that PKCα stimulated p47^phox/NADPH oxidase 2 (Nox2)-dependent reactive oxygen species (ROS) generation and then activated the ATF2/AP-1 signals. The activated-ATF2 bound to the AP-1-binding site of MMP-9 promoter, and thereby turned on MMP-9 gene transcription. Additionally, the co-activator p300 also contributed to these responses. Functionally, LTA-induced MMP-9 expression enhanced astrocytic migration.</p> <p>Conclusion</p> <p>These results demonstrated that in RBA-1 cells, activation of ATF2/AP-1 by the PKC(α)-mediated Nox(2)/ROS signals is essential for upregulation of MMP-9 and cell migration enhanced by LTA.</p

Justify your alpha

Benjamin et al. proposed changing the conventional “statistical significance” threshold (i.e.,the alpha level) from p ≤ .05 to p ≤ .005 for all novel claims with relatively low prior odds. They provided two arguments for why lowering the significance threshold would “immediately improve the reproducibility of scientific research.” First, a p-value near .05provides weak evidence for the alternative hypothesis. Second, under certain assumptions, an alpha of .05 leads to high false positive report probabilities (FPRP2 ; the probability that a significant finding is a false positive

Extensive innate immune gene activation accompanies brain aging, increasing vulnerability to cognitive decline and neurodegeneration: a microarray study

BACKGROUND: This study undertakes a systematic and comprehensive analysis of brain gene expression profiles of immune/inflammation-related genes in aging and Alzheimer’s disease (AD). METHODS: In a well-powered microarray study of young (20 to 59 years), aged (60 to 99 years), and AD (74 to 95 years) cases, gene responses were assessed in the hippocampus, entorhinal cortex, superior frontal gyrus, and post-central gyrus. RESULTS: Several novel concepts emerge. First, immune/inflammation-related genes showed major changes in gene expression over the course of cognitively normal aging, with the extent of gene response far greater in aging than in AD. Of the 759 immune-related probesets interrogated on the microarray, approximately 40% were significantly altered in the SFG, PCG and HC with increasing age, with the majority upregulated (64 to 86%). In contrast, far fewer immune/inflammation genes were significantly changed in the transition to AD (approximately 6% of immune-related probesets), with gene responses primarily restricted to the SFG and HC. Second, relatively few significant changes in immune/inflammation genes were detected in the EC either in aging or AD, although many genes in the EC showed similar trends in responses as in the other brain regions. Third, immune/inflammation genes undergo gender-specific patterns of response in aging and AD, with the most pronounced differences emerging in aging. Finally, there was widespread upregulation of genes reflecting activation of microglia and perivascular macrophages in the aging brain, coupled with a downregulation of select factors (TOLLIP, fractalkine) that when present curtail microglial/macrophage activation. Notably, essentially all pathways of the innate immune system were upregulated in aging, including numerous complement components, genes involved in toll-like receptor signaling and inflammasome signaling, as well as genes coding for immunoglobulin (Fc) receptors and human leukocyte antigens I and II. CONCLUSIONS: Unexpectedly, the extent of innate immune gene upregulation in AD was modest relative to the robust response apparent in the aged brain, consistent with the emerging idea of a critical involvement of inflammation in the earliest stages, perhaps even in the preclinical stage, of AD. Ultimately, our data suggest that an important strategy to maintain cognitive health and resilience involves reducing chronic innate immune activation that should be initiated in late midlife

Justify your alpha

In response to recommendations to redefine statistical significance to p ≤ .005, we propose that researchers should transparently report and justify all choices they make when designing a study, including the alpha level

Analiza porównawcza odporności na zużywanie ścierne stali Brinar i Hardox

One of the most important problems encountered during operation of machine parts exposed to abrasive action is their wear. In addition, these parts often work under dynamic loads, so their satisfactory ductility is also required. A combination of these apparently opposing properties is to a large degree possible in low-alloy martensitic steels containing boron. These steels are manufactured by numerous metallurgical concerns, but their nomenclature is not standardised and they appear under names given by the manufacturers, and their specifications are available in commercial information materials only. Till now, Hardox steels have been objects of great interest but, with regard to the continuous development of materials engineering, the created material database requires regular supplementation. To that end, two grades of steels from this group, Brinar 400 and Brinar 500, were subjected to comparative analysis of their abrasive-wear resistance in relation to properties of competitive grades Hardox 400 and Hardox 500. Abrasive-wear resistance tests were carriedout in laboratory conditions using a tribotester T-07. In addition, to identify the main wear mechanisms, worn surfaces of the specimens were examined with use of a scanning electron microscope.Jednym z najważniejszych problemów, na jaki napotyka się podczas eksploatacji elementów maszyn narażonych na działanie masy ściernej, jest ich zużywanie. Dodatkowo elementy te pracują często w warunkach obciążeń o charakterze dynamicznym, stąd wymaga się od nich również zadowalającej ciągliwości. Połączenie tych, na pierwszy rzut oka, przeciwstawnych właściwości było w dużej mierze możliwe w niskostopowych, martenzytycznych stalach z borem. Stale te są produkowane przez wiele koncernów hutniczych, ale nazewnictwo ich nie jest znormalizowane i występują pod nazwami nadanymi im przez producentów, a dane o nich dostępne są jedynie w materiałach komercyjnych. Do tej pory intensywnie zajmowano się stalami typu Hardox, ale w związku z ciągłym rozwojem inżynierii materiałowej stworzona baza materiałowa wymaga stałych uzupełnień. W tym celu analizie porównawczej, pod względem odporności na zużywanie ścierne, poddano kolejne dwa gatunki należące do tej grupy stali – Brinar 400 i Brinar 500, których właściwości odniesiono do konkurencyjnych stali Hardox 400 i Hardox 500. Badania odporności na zużywanie ścierne tych stali zrealizowano w warunkach laboratoryjnych za pomocą tribotestera T-07. Dodatkowo, w celu zidentyfikowana głównych mechanizmów zużywania, za pomocą elektronowego mikroskopu skaningowego (SEM) zostały przeprowadzone badania wyeksploatowanych powierzchni próbek analizowanych stali

Właściwości strukturalne i odporność na zużywanie ścierne stali Brinar 400 i Brinar 500

In the paper, microstructures and the examination results of abrasive-wear resistance of steel grades Brinar 400 and Brinar 500 are presented. It was found on the grounds of light and electron scanning microscopy that these steels are characterised by subtle differences in microstructures, influencing their mechanical and usable properties. In as-delivered condition, the steels have fine-grained structure with post-martensitic orientation, containing few particles of carbide phases. Such microstructures of Brinar steels and the performed chemical analyses indicate that their properties are formed during specialised operations of thermo-mechanical rolling. Generally, it can be said that the examined steels were designed according to the accepted standards of material engineering, related to low-alloy, high-strength, and abrasive-wear resistant martensitic steels. According to the above, the obtained results of structural examinations of Brinar 400 and Brinar 500 steels were referred to real abrasive-wear indices obtained by the spinning bowl method with use of various abrasive soil masses. The tests carried-out in light soil (loamy sand), medium soil (sandy loam), and in heavy soil (loam), as well as hardness measurements showed strict dependence of abrasive-wear indices on microstructures and the heattreatment condition of the examined steels. Examination results of abrasive-wear resistance of Brinar steels were compared with those of steel 38GSA in normalised conditions.W pracy przedstawiono budowę strukturalną oraz wyniki badań odporności na zużywanie ścierne stali Brinar 400 i Brinar 500. Na podstawie przeprowadzonych metodami mikroskopii świetlnej i skaningowej badań wykazano, że stale te cechują się subtelną różnicą w budowie strukturalnej rzutującą na ich charakterystyki wytrzymałościowe i użytkowe. W stanie dostarczenia rozpatrywane stale charakteryzują się drobnoziarnistą strukturą o orientacji pomartenzytycznej z nielicznymi wydzieleniami faz węglikowych. Powyższy typ budowy strukturalnej stali Brinar oraz przeprowadzone analizy spektralne składu chemicznego wskazują, iż ich właściwości kształtowane są w toku specjalistycznych zabiegów termomechanicznego walcowania. Ogólnie rzecz biorąc, można stwierdzić, że badane stale zostały zaprojektowane zgodnie z przyjętymi kanonami inżynierii materiałowej odnośnie do niskostopowych, wysokowytrzymałych stali martenzytycznych odpornych na zużywanie ścierne. Zgodnie z powyższym uzyskane wyniki badań strukturalnych stali Brinar 400 i Brinar 500 odniesiono do rzeczywistych wskaźników odporności na zużycie ścierne uzyskanych metodą „wirującej misy” z wykorzystaniem zróżnicowanych glebowych mas ściernych. Zrealizowane badania w glebie lekkiej (piasek gliniasty), glebie średniej (glina lekka) oraz glebie ciężkiej (glina zwykła), a także przeprowadzone pomiary twardości wykazały ścisłą zależność uzyskanych wskaźników odporności na zużywanie ścierne od budowy fazowej oraz od stanu obróbki cieplnej badanych stali. Wyniki badań odporności na zużywanie ścierne stali Brinar odniesiono porównawczo do stali 38GSA w stanie normalizowanym

Fractographic Analysis Of Selected Boron Steels Subjected To Impact Testing

In this paper dynamic properties of low-alloy boron steels – Hardox 500, B27 and HTK 900H in delivered state (after hardening and tempering) are considered. Charpy V-notch (CVN) test results in connection with fractography in the ductile-to-brittle transition temperature region were analyzed. Obtained from CVN test the impact transition curve, not always predicts properly a behavior of materials in conditions of dynamic loading. So an analyze of character of fracture helps to evaluate the real behavior of materials. Tested samples were cut out longitudinally in relation to cold work direction. The results of CVN test for selected steels, in temperatures: −40°C, −20°C, 0°C and +20°C are presented. Regarding ductile-to-brittle transition temperature, there is a significant difference taking into account values of Charpy V energy absorbed and a character of fracture

Peripheral challenge with a viral mimic upregulates expression of the complement genes in the hippocampus

Peripheral challenge with a viral mimetic, polyinosinic-polycytidylic acid (PIC) induces hippocampal hyperexcitability in mice. Here, we characterized this hippocampal response through a whole genome transcriptome analysis. Intraperitoneal injection of PIC resulted in temporal dysregulation of 625 genes in the hippocampus, indicating an extensive genetic reprogramming. The bioinformatics analysis of these genes revealed the complement pathway to be the most significantly activated. The gene encoding complement factor B (CfB) exhibited the highest response, and its upregulation was commensurate with the development of hyperexcitability. Collectively, these results suggest that the induction of hippocampal hyperexcitability may be mediated by the alternative complement cascades