Platelet-endothelial cell adhesion molecule (PECAM)-1 has been implicated in leukocyte migration through the perivascular basement membrane (PBM) though the mechanisms involved are unclear. The present results demonstrate that the ability of α6 integrins to mediate neutrophil migration through the PBM is PECAM-1 dependent, a response associated with PECAM-1–mediated increased expression of α6β1 on transmigrating neutrophils in vivo. An anti-α6 integrins mAb (GoH3) inhibited (78%, P < 0.001) neutrophil migration through interleukin (IL)-1β–stimulated cremasteric venules, primarily at the level of the PBM, as analyzed by intravital and electron microscopy. In PECAM-1–deficient mice (KO), a reduced level of neutrophil transmigration elicited by IL-1β (4-h reaction) was observed in both the cremaster muscle (55% inhibition, P < 0.05) and in the peritoneum (57% inhibition, P < 0.01) but GoH3 had no additional inhibitory effect on these responses. FACS® analysis of neutrophils demonstrated increased expression of α6β1 on transmigrated peritoneal neutrophils, as compared with blood neutrophils, in wild-type but not KO mice even though neutrophils from both strains of mice exhibited comparable levels of intracellular expression of α6 as observed by immunofluorescent staining and confocal microscopy. Furthermore, mice deficient in either leukocyte or endothelial cell PECAM-1, as developed by bone marrow transplantation, demonstrated a similar level of reduced neutrophil transmigration and expression of α6β1 on transmigrated neutrophils as that detected in KO mice.The results demonstrate a role for PECAM-1 homophilic interaction in neutrophil transmigration and increased expression of α6β1 on the cell surface of transmigrated neutrophils in vivo, a response that could contribute to the mechanism of PECAM-1–mediated neutrophil migration through the PBM.

Parkinson's disease (PD) is a progressive disease related to degeneration of nigrostriatal dopaminergic neurons and can be caused by genetic and environmental factors. N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can produce Parkinsonian syndrome (Langston et al. 1983) and is an Received February 28, 2010; revised manuscript received April 26, 2010; accepted April 26, 2010. Address correspondence and reprint requests to Kai-Yuan Tzen, MD, Department of Nuclear Medicine, National Taiwan University Hospital, No.7 Chung Shan South Road, Taipei 100, Taiwan. E-mail: tzenky@ntuh.gov.tw or Chun-Jung Lin, School of Pharmacy, College of Medicine, National Taiwan University,1 Jen-Ai Road, Section 1, Taipei, Taiwan 100. E-mail: clementumich@ntu.edu.tw Abbreviations used: 3-MT, 3-methoxytyramine; ARBECs, adult rat brain endothelial cells; AUC, area under the time-concentration curve; BB, blood-brain barrier; BMECs, brain microvessel endothelial cells; BSA, bovine serum albumin; DC, detergent compatible; DOPAC, 3,4-dihydroxyphenylacetic acid; ECF, extracellular fluid; FDOPA, 6-[ AbstractThe cellular localization of organic cation transporter (OCT) 1 and OCT2 in isolated brain microvessel endothelial cells from humans, rats, and mice and in cultured adult rat brain endothelial cells was examined by confocal microscopy and in isolated luminal and abluminal membrane fractions by Western blot analysis. Cellular uptake of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was measured with or without OCT1/OCT2 silencing. The interaction between MPTP and amantadine was studied by in vitro kinetic analysis and in vivo brain microdialysis. MPTP-induced dopaminergic toxicity was examined by measuring dopamine levels in the brain striatum and by positron emission tomography scanning. The results showed that both OCT1 and OCT2 were mainly expressed on the luminal side of brain microvessel endothelial cells and adult rat brain endothelial cells. Cellular uptake of MPTP was significantly (p < 0.05) decreased by about 53%, 60%, or 91% following silencing of OCT1, OCT2, or both, respectively. Amantadine competitively inhibited MPTP uptake in vitro and significantly (p < 0.05) reduced the area under the time-concentration curve for MPTP and MPP + in the brain extracellular fluid in rats and mice by 65-70% and 35-85%, respectively. MPTP-induced dopaminergic toxicity in mice was ameliorated by amantadine without stimulating dopamine turnover. In conclusion, OCT1 and OCT2 are important for MPTP transfer across the blood-brain barrier and amantadine reduces the blood-brain barrier transfer of MPTP and MPTP-induced dopaminergic toxicity in rodents.

BackgroundNotch and TLR pathways were found to act cooperatively to activate Notch target genes and to increase the production of TLR-induced cytokines in macrophages. However, the mechanism of LPS-induced Notch activation and its role in sepsis still remains unclear.MethodsWe analyzed the expression patterns of Notch components in a LPS-stimulated murine macrophage cell line using real-time PCR and western blotting. The role of DAPT, a gamma-secretase inhibitor that is known to be a potent Notch inhibitor, in LPS-induced cytokine release and experimental sepsis in mice was also explored. Student's t-test was used to analyze the difference between the two groups.ResultsWe found that Notch signaling was activated after LPS stimulation. The expression of Jagged 1, a Notch ligand, induced by LPS occurred in a JNK-dependent manner. In addition, Notch target genes were upregulated by early Notch-independent activation followed by delayed Notch-dependent activation after LPS stimulation. Disruption of Notch signaling by DAPT attenuated the LPS-induced inflammatory responses, including vascular endothelial growth factor (VEGF) and high-mobility group box chromosomal protein 1 (HMGB1), both in vitro and in vivo and partially improved experimental sepsis survival.ConclusionsThese findings support the existence of a synergistic effect of Notch signaling and the LPS pathway both in vitro and in vivo. Therefore, in the future Notch inhibitors may be utilized as adjunctive agents for the treatment of sepsis syndrome.

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Endothelial junctions maintain endothelial integrity and vascular homeostasis. They modulate cell trafficking into tissues, mediate cell-cell contact and regulate endothelial survival and apoptosis. Junctional adhesion molecules such as vascular endothelial (VE)-cadherin and CD31/platelet endothelial cell adhesion molecule (PECAM) mediate contact between adjacent endothelial cells and regulate leukocyte transmigration and angiogenesis. The leukocyte adhesion molecule intercellular adhesion molecule 2 (ICAM-2) is expressed at the endothelial junctions.In this study we demonstrate that endothelial ICAM-2 also mediates angiogenesis. Using ICAM-2-deficient mice and ICAM-2-deficient endothelial cells, we show that the lack of ICAM-2 expression results in impaired angiogenesis both in vitro and in vivo. We show that ICAM-2 supports homophilic interaction, and that this may be involved in tube formation. ICAM-2-deficient cells show defective in vitro migration, as well as increased apoptosis in response to serum deprivation, anti-Fas antibody, or staurosporine. ICAM-2 signaling in human umbilical vein endothelial cells (HUVECs) was found to activate the small guanosine triphosphatase (GTPase) Rac, which is required for endothelial tube formation and migration. These data indicate that ICAM-2 may regulate angiogenesis via several mechanisms including survival, cell migration, and Rac activation. Our findings identify a novel pathway regulating angiogenesis through ICAM-2 and a novel mechanism for Rac activation during angiogenesis. IntroductionAngiogenesis involves a cascade of events that requires the disassembly of endothelial junctions, followed by detachment, proliferation, and migration of endothelial cells (ECs), and finally the re-establishment of cell-cell and cell-matrix contacts. 1 Adhesion molecules at the endothelial junctions, such as CD31/platelet endothelial cell adhesion molecule (PECAM) and junctional adhesion molecule (JAM)-A, support endothelial cell-cell contact through homophilic binding, and are involved in regulating endothelial homeostasis and angiogenesis via different mechanisms. Junctional molecules also mediate leukocyte transendothelial migration through homophilic or heterophilic interactions with leukocytes. 2 Intercellular adhesion molecule 2 (ICAM-2) is a member of the immunoglobulin (Ig) superfamily, constitutively expressed at the endothelial junctions. 3 Its structure includes 2 extracellular Ig domains, a transmembrane region, and a short intracellular tail. 4 ICAM-2, originally identified as a ligand for leukocyte integrin lymphocyte function-associated antigen-1 (LFA-1), 4 also interacts with the integrin Mac-1 5 and the dendritic cell receptor DC-SIGN (dendritic cell-specific ICAM-3-grabbing nonintegrin). 6 Through these interactions, ICAM-2 mediates leukocyte trafficking. 4,6,7 Recent data indicate that ICAM-2 involvement in leukocyte transmigration may be stimulus specific. 8 However its role in inflammation is still unclear: inflammatory cytokines that up-regulate the expressi...

The reaction between CH2 (X3B1) + O2 in the gas phase was investigated by carrying out CASSCF and CASPT2 calculations with the 6-31G(d,p) and 6-311+G(3df,2p) basis sets. The reaction proceeds by the addition of O2 to methylene and may follow a singlet and a triplet potential energy surface. In both cases, its fate is the carbonyl oxide (H2COO). The reaction in its singlet multiplicity is computed to be exothermic by 50.9 kcal/mol with an activation enthalpy of 1.9 kcal/mol at 298 K. The reaction in its triplet multiplicity is computed to be exothermic by 26.9 kcal/mol with an activation enthalpy of 5.4 kcal/mol at 298 K. According to classical transition state theory, the branching ratio for the reaction in its triplet state multiplicity changes from negligible at 298 K to about 26% at 1800 K, and this ratio equals the formation of atomic oxygen (O, 3P). The following unimolecular decomposition of carbonyl oxides in its singlet and triplet multiplicity was also considered.

The synthesis and characterization of a singlet delocalized 2,4-diimino-1,3-disilacyclobutanediyl, [LSi(μ-CNAr)(2)SiL] (2, L: PhC(NtBu)(2), Ar: 2,6-iPr(2) C(6) H(3)), and a silylenylsilaimine, [LSi(=NAr)-SiL] (3), are described. The reaction of three equivalents of the disilylene [LSi-SiL] (1) with two equivalents of ArN=C=NAr in toluene at room temperature for 12 h afforded [LSi(μ-CNAr)(2)SiL] (2) and [LSi(=NAr)-SiL] (3) in a ratio of 1:2. Compounds 2 and 3 have been characterized by NMR spectroscopy and X-ray crystallography. Compound 2 was also investigated by theoretical studies. The results show that compound 2 possesses singlet biradicaloid character with an extensive electronic delocalization throughout the Si(2)C(2) four-membered ring and exocyclic C=N bonds. Compound 3 is the first example of a silylenylsilaimine, which contains a low-valent silicon center and a silaimine substituent. A mechanism for the formation of 2 and 3 is also proposed.

Objectives: Recent metabolomic studies of sepsis showed that increased circulatory acylcarnitines were associated with worse survival. However, it is unknown whether plasma carnitine and acylcarnitines can reflect the severity of sepsis, and the role of specific acylcarnitines in prognostic assessment need further confirmation. This study aimed to clarify these questions. Design: Prospective multicenter cohort studies with derivation and validation cohort design. Setting: ICUs at two medical centers and three regional hospitals in Taiwan. Patients: Patients with sepsis and acute organ dysfunction were enrolled. Recruitment of the derivation (n = 90) and validation cohorts (n = 120) occurred from October 2010 through March 2012 and January 2013 through November 2014, respectively. Interventions: Plasma samples were collected immediately after admission, and the levels of carnitine and acylcarnitines were measured by ultra-high performance liquid chromatography-mass spectrometry. Measurements and Main Results: In the derivation cohort, increased plasma levels of short- and medium-chain acylcarnitines were significantly associated with hepatobiliary dysfunction, renal dysfunction, thrombocytopenia, and hyperlactatemia. However, acetylcarnitine is the only acylcarnitine significantly correlating with various plasma cytokine concentrations and also associated with blood culture positivity and 28-day mortality risk. The association between plasma acetylcarnitine and multiple organ dysfunction severity, blood culture positivity, and 28-day mortality, was confirmed in the validation cohort. Patients with high plasma acetylcarnitine (≥ 6,000 ng/mL) had significantly increased 28-day mortality compared with those with plasma acetylcarnitine less than 6,000 ng/mL (52.6% vs 13.9%; hazard ratio, 5.293; 95% CI, 2.340–11.975; p < 0.001 by Cox proportional hazard model). Conclusions: We confirm that plasma acetylcarnitine can reflect the severity of organ dysfunction, inflammation, and infection in sepsis and can serve as a prognostic biomarker for mortality prediction.