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Biomedical subjects

Kirsi Harju

Publications and source records attributed to Kirsi Harju.

7 recordsLinked to original sources
PubMed2005

TLR-2 is upregulated and mobilized to the hepatocyte plasma membrane in the space of Disse and to the Kupffer cells TLR-4 dependently during acute endotoxemia in mice.

Membrane components of bacteria and fungi are recognized by Toll-like receptors (TLRs) which, when activated, induce several inflammatory mediators important in the host defense. As the liver is constantly exposed to ingested bacteria, hepatic TLRs must be broadly responsive and highly regulated to prevent uncontrolled inflammatory activation. Although several hepatic cells express microbe recognition molecules and inflammatory mediators in vitro, the regulation and cellular localization of these proteins in vivo remain uncertain. The expression and regulation of TLR-2 and TLR-4, and the cytokine expression patterns were evaluated in mouse tissues using a model of acute inflammation induced by intraperitoneal injection of LPS. Five hours after intraperitoneal LPS, induction of TLR-4 was evident in lung, while the low hepatic TLR-4 expression was non-inducible. TLR-2 mRNA and protein were induced both in lung and liver TLR-4 dependently. However, IL-1alpha also contributed to this induction, and IL-1R1 antibody attenuated the TLR-2 increase. Immunoelectron microscopy showed accumulation of cytoplasmic TLR-2 to vesicles near the hepatocyte plasma membrane in the space of Disse, to the sinusoidal endothelium and to the Kupffer cells. NF-kappaB activation was clear in Kupffer cells and hepatocytes during LPS-challenge, suggesting these cells to be the main source of in vivo cytokine production. Hepatic cytokine response to LPS was remarkably rapid in liver, whereas lung responded less acutely. Secondary inflammatory challenge attenuated the TLR-2 response. The innate immune system of the liver is rapidly and transiently activated during endotoxemia by mechanism involving both TLR-4 and TLR-2.

Animals↗
PubMed2005

Analysis of small molecules by ultra thin-layer chromatography-atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry.

The feasibility of ultra thin-layer chromatography atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry (UTLC-AP-MALDI-MS) has been studied in the analysis of small molecules. Because of a thinner adsorbent layer, the monolithic UTLC plates provide 10-100 times better sensitivity in MALDI analysis than conventional high performance thin-layer chromatography (HPTLC) plates. The limits of detection down to a low picomole range are demonstrated by UTLC-AP-MALDI-MS. Other advantages of UTLC over HPTLC include faster separations and lower solvent consumption. The performances of AP-MALDI-MS and vacuum MALDI-MS have been compared in the analysis of small drug molecules directly from the UTLC plates. The desorption from the irregular surface of UTLC plates with an external AP-MALDI ion source combined with an ion trap instrument provides clearly less variation in measurements of m/z values when compared with a vacuum MALDI-time-of-flight (TOF) instrument. The performance of the UTLC-AP-MALDI-MS method has been applied successfully to the purity analysis of synthesis products produced by solid-phase parallel synthesis method.

Atmospheric Pressure↗
PubMed2005

Expression of toll-like receptor 4 and endotoxin responsiveness in mice during perinatal period.

Endotoxin [lipopolysaccharide (LPS)] from Gram-negative bacteria is found in amniotic fluid in intrauterine infections that associate with the risk for spontaneous premature birth, bronchopulmonary dysplasia (BPD), and respiratory distress syndrome. Toll-like receptor 4 (TLR4) is the signaling receptor for LPS. The aim was to investigate the primary inflammatory response in mice shortly after administration of LPS to the dam (14 and 17 d of pregnancy), to the newborn, or into the amniotic fluid. The expression levels of TLR4, IL-1, tumor necrosis factor-alpha, IL-6, IL-10, macrophage inflammatory protein-2, and IL-1 receptor 1 were studied with ribonuclease protection assay. In addition, TLR4 protein was analyzed with Western blotting. The fetal membranes expressed TLR4 mRNA and protein and showed an acute cytokine response to LPS when LPS was administrated into the amniotic fluid. There was distinct ontogeny in the responsiveness of fetal lung to LPS: on fetal day 14 (term 20 d), both the expression of TLR4 and the acute cytokine response were undetectable 5 h after LPS; they became detectable by fetal day 17. TLR4 and the cytokine response further increased after birth. In maternal lung, the TLR4 expression was strongest and up-regulated in parallel with the induction of the cytokines. We propose that TLR4 controls the magnitude of the LPS-induced cytokine response during the perinatal period.

Alleles↗
PubMed2005

Recent advances in 1,3-dipolar cycloaddition reactions on solid supports.

Solid-phase methods are of a great significance in organic synthesis. Recent developments of these methods are providing new ways to construct libraries of small organic molecules. Five-membered heterocyclic compounds, which can be utilized in a variety of applications, are formed in the 1,3-dipolar cycloaddition reaction between dipolarophiles and dipoles. This review deals with the solid-phase synthesis of heterocycles via [3+2] cycloaddition reaction. Cycloaddition reactions of polymer-bound dipoles and polymer-bound dipolarophiles and intramolecular solid-phase cycloadditions are discussed in separate sections. Reactions of dipolarophiles such as alkenes, alkynes, and imines with dipoles such as azomethine ylides, azomethine imines, nitrile imines, azides, nitrones, and nitrile oxides are described. The recent literature up to December 2003 is covered.

Chemistry, Organic↗
PubMed2003

Phosphatidylinositol 3-kinase is involved in Toll-like receptor 4-mediated cytokine expression in mouse macrophages.

Recent evidence suggests a role for phosphatidylinositol (PI) 3-kinase in various inflammatory responses. In this study, the consequences of LPS-induced PI 3-kinase activation on cytokine and chemokine expression and the intracellular mechanisms of inflammatory activation were examined in mouse macrophages. LPS stimulation induced a complex formation between PI 3-kinase and myeloid differentiation factor 88 (MyD88), which was followed by an induction of IL-1beta, tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein (MIP)-2. The induction of IL-1beta, but not of MIP-2 or TNF-alpha, was blocked by the PI 3-kinase inhibitors LY294002 and wortmannin. The nuclear factor-kappaB (NF-kappaB) inhibitor pyrrolidinedithiocarbamate (PDTC) blocked the induction of IL-1beta and TNF-alpha, but had no effect on MIP-2 expression. Inhibition of PI 3-kinase decreased the LPS-induced transcriptional activity of NF-kappaB, but it had no effect on the nuclear DNA binding activity of NF-kappaB. These findings suggest that, while NF-kappaB nuclear localization and DNA binding are necessary, they are not sufficient for transcriptional activation of the IL-1beta gene in the absence of PI 3-kinase activity. Taken together, our results demonstrate that activation of Toll-like receptor (TLR)-4 results in PI 3-kinase-MyD88 complex formation, and that PI 3-kinase activity selectively leads to cytokine induction downstream of TLR4.

Adaptor Proteins, Signal Transducing↗
PubMedDate not supplied

Solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition.

The solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition of polymer-bound azides to various alkynes is reported. Polymer-bound azides were synthesized from polymer-bound halides and sodium azide and reacted with alkynes to produce polymer-bound 1,2,3-triazoles. Cleavage of the triazoles was performed with trifluoroacetic acid. A traceless synthesis of 1,2,3-triazoles was developed using 2-methoxy-substituted resin (polymer-bound 4-hydroxy-2-methoxybenzyl alcohol). In addition, a synthesis of 4-hydroxybenzyl-substituted 1,2,3-triazoles from the bromo-Wang resin (4-(bromomethyl)phenoxymethyl polystyrene) was achieved.

Technology, Pharmaceutical↗