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Hospital services are reduced during off-hour such as nighttime or weekend. Investigations of the off-hour effect on initial management and outcomes in sepsis are very limited. Thus, we tested the hypothesis that patients who were diagnosed with severe sepsis during the nighttime or on non-business days had altered initial management and clinical outcomes.

ABSTRACTThe integration of external staff into a hospital’s disaster response can present technical challenges. Although hospitals will always prefer to use their own staff in disaster response, there have been many historical examples where external staffing is required. During the 2016 Kumamoto Earthquakes, the Oita Prefectural Hospital required medical professionals to expand disaster response staff. They were able to identify 2 appropriate emergency physicians belonging to a remote hospital who had previously worked at the Oita Prefectural hospital. The physicians were effectively able to supplement the hospital staff, providing care for additional patients, and giving the existing on-duty staff some respite. Based on our experience, we suggest that hospital coalitions and disaster response authorities explore mechanisms of cross-credentialing and cross-training staff to make it easier to share staff in a disaster.

Although the serum 1,3-ß-D-glucan test has been used as an early diagnostic marker of candidemia, there are few studies regarding the association of serum 1,3-ß-D-glucan levels with candidemia in severe burn patients. The purpose of this study was to elucidate the clinical significance of 1,3-ß-D-glucan for the diagnosis of candidemia in severe burn patients. Data from 51 severe burn patients whose serum levels of 1,3-ß-D-glucan had been measured for the suspicion of invasive fungal infection were analyzed retrospectively. The primary outcome in this study was the detection of candidemia. The levels of 1,3-ß-D-glucan (pg/ml) in candidemia and noncandidemia groups ranged from 41.1 to 600.0 with a median of 90.6 and from 5.0 to 41.3 with a median of 6.8, respectively. A significant difference in the levels of 1,3-ß-D-glucan was observed between the two groups. The optimal cutoff value was 40 pg/ml, with a sensitivity of 100% and a specificity of 95%, whereas the conventional cutoff value (11 pg/ml) resulted in a sensitivity of 100% and a specificity of 68%. The 1,3-ß-D-glucan test was found to be useful for detecting candidemia in severe burn patients, and the cutoff value might be set to 40 pg/ml to detect it more accurately.

In cancer and angiogenesis, coagulation-independent roles of tissue factor (TF) in cell migration are incompletely understood. Immobilized anti-TF extracellular domain antibodies induce cell spreading, but this phenomenon is epitope specific and is not induced by anti-TF 5G9. Spreading on anti-TF is β1 integrin–dependent, indicating functional interactions of the TF extracellular domain 5G9 epitope (a presumed integrin-binding site) and integrins. Recombinant TF extracellular domain supports adhesion of cells expressing αvβ3 or certain β1 integrin heterodimers (α3β1, α4β1, α5β1, α6β1, α9β1) and adhesion is blocked by specific anti-integrin antibodies or mutations in the integrin ligand-binding site. Although several studies have linked TF to cell migration, we here demonstrate that TF specifically regulates α3β1-dependent migration on laminin 5. Expression of TF suppresses α3β1-dependent migration, but only when the TF cytoplasmic domain is not phosphorylated. Suppression of migration can be reversed by 5G9, presumably by disrupting integrin interaction, or by the protease ligand VIIa, known to induce PAR-2–dependent phosphorylation of TF. In both cases, release of α3β1 inhibition is prevented by mutation of critical phosphorylation sites in the TF cytoplasmic domain. Thus, TF influences integrin-mediated migration through cooperative intra- and extracellular interactions and phosphorylation regulates TF's function in cell motility.

Angiostatin, a plasminogen fragment containing 3–4 N-terminal kringle domains, is a potent inhibitor of tumor-induced angiogenesis, but its mechanism of action is unclear. Angiostatin is a ligand for integrin αvβ3but does not induce stress fiber formation upon integrin binding, suggesting that angiostatin is a potential integrin antagonist. Plasmin, the parent molecule of angiostatin and a major extracellular protease, induces platelet aggregation, migration of peripheral blood monocytes, and release of arachidonate and leukotriene from several cell types. In the current study, we found that plasmin specifically bound to αvβ3through the kringle domains and induced migration of endothelial cells. In contrast, angiostatin did not induce cell migration. Notably, angiostatin, anti-αvβ3antibodies, RGD-peptide, and a serine protease inhibitor effectively blocked plasmin-induced cell migration. These results suggest that plasmin-induced migration of endothelial cells requires αvβ3and the catalytic activity of plasmin and that this process is a potential target for the inhibitory activity of angiostatin.

ADAMs (adisintegrin and metalloproteases) are members of the metzincin superfamily of metalloproteases. Among integrins binding to disintegrin domains of ADAMs are α9β1and αvβ3, and they bind in an RGD-independent and an RGD-dependent manner, respectively. Human ADAM15 is the only ADAM with the RGD motif in the disintegrin domain. Thus, both integrin α9β1and αvβ3recognize the ADAM15 disintegrin domain. We determined how these integrins recognize the ADAM15 disintegrin domain by mutational analysis. We found that the Arg481and the Asp-Leu-Pro-Glu-Phe residues (residues 488–492) were critical for α9β1binding, but the RGD motif (residues 484–486) was not. In contrast, the RGD motif was critical for αvβ3binding, but the other residues flanking the RGD motif were not. As the R X6DLPEF α9β1recognition motif (residues 481–492) is conserved among ADAMs, except for ADAM10 and 17, we hypothesized that α9β1may recognize disintegrin domains in all ADAMs except ADAM10 and 17. Indeed we found that α9β1bound avidly to the disintegrin domains of ADAM1, 2, 3, and 9 but not to the disintegrin domains of ADAM10 and 17. As several ADAMs have been implicated in sperm-oocyte interaction, we tested whether the functional classification of ADAMs, based on specificity for integrin α9β1, applies to sperm-egg binding. We found that the ADAM2 and 15 disintegrin domains bound to oocytes, but the ADAM17 disintegrin domain did not. Furthermore, the ADAM2 and 15 disintegrin domains effectively blocked binding of sperm to oocytes, but the ADAM17 disintegrin domain did not. These results suggest that oocytes and α9β1have similar binding specificities for ADAMs and that α9β1, or a receptor with similar specificity, may be involved in sperm-egg interaction during fertilization. As α9β1is a receptor for many ADAM disintegrins and α9β1and ADAMs are widely expressed, α9β1-ADAM interaction may be of a broad biological importance.

Integrins mediate cell adhesion and signal transduction at focal adhesions. Here we investigate the roles of integrin β subunits in the regulation of actin cytoskeletal structure and the activities of Rho and Rac. The overexpression of β3 integrin in Chinese hamster ovary cells enhances Rho activity and stress fiber formation, whereas the overexpression of β1 integrin increases Rac activity and lamellipodia formation. The overexpression of a mutant β1-3-1 integrin, in which the extracellular I-domain-like sequence of β1 integrin has been replaced with the corresponding sequence of β3 integrin, also enhances Rho activity and the formation of stress fibers. Our results demonstrate that β1 and β3 integrins differentially regulate the activities of Rho family GTPases and that the extracellular domains of integrin β subunits play a critical role in transducing the extracellular ligand-binding information into specific intracellular signaling events.

Angiostatin, the N-terminal four kringles (K1–4) of plasminogen, blocks tumor-mediated angiogenesis and has great therapeutic potential. However, angiostatin's mechanism of anti-angiogenic action is unclear. We found that bovine arterial endothelial (BAE) cells adhere to angiostatin in an integrin-dependent manner and that integrins αvβ3, α9β1, and to a lesser extent α4β1, specifically bind to angiostatin. αvβ3is a predominant receptor for angiostatin on BAE cells, since a function-blocking antibody to αvβ3effectively blocks adhesion of BAE cells to angiostatin, but an antibody to α9β1does not. ε-Aminocaproic acid, a Lys analogue, effectively blocks angiostatin binding to BAE cells, indicating that an unoccupied Lys-binding site of the kringles may be required for integrin binding. It is known that other plasminogen fragments containing three or five kringles (K1–3 or K1–5) have an anti-angiogenic effect, but plasminogen itself does not. We found that K1–3 and K1–5 bind to αvβ3, but plasminogen does not. These results suggest that the anti-angiogenic action of angiostatin may be mediated via interaction with αvβ3. Angiostatin binding to αvβ3does not strongly induce stress-fiber formation, suggesting that angiostatin may prevent angiogenesis by perturbing the αvβ3-mediated signal transduction that may be necessary for angiogenesis.

Binding of urokinase-type plasminogen activator (uPA) to its receptor (uPAR/CD87) regulates cellular adhesion, migration, and tumor cell invasion. However, it is unclear how glycosyl phosphatidylinositol-anchored uPAR, which lacks a transmembrane structure, mediates signal transduction. It has been proposed that uPAR forms cis-interactions with integrins as an associated protein and thereby transduces proliferative or migratory signals to cells upon binding of uPA. We provide evidence that soluble uPAR (suPAR) specifically binds to integrins α4β1, α6β1, α9β1, and αvβ3 on Chinese hamster ovary cells in a cation-dependent manner. Anti-integrin and anti-uPAR antibodies effectively block binding of suPAR to these integrins. Binding of suPAR to α4β1 and αvβ3 is blocked by known soluble ligands and by the integrin mutations that inhibit ligand binding. These results suggest that uPAR is an integrin ligand rather than, or in addition to, an integrin-associated protein. In addition, we demonstrate that glycosyl phosphatidylinositol-anchored uPAR on the cell surface specifically binds to integrins on the apposing cells, suggesting that uPAR-integrin interaction may mediate cell-cell interaction (trans-interaction). These previously unrecognized uPAR-integrin interactions may allow uPAR to transduce signals through the engaged integrin without a hypothetical transmembrane adapter and may provide a potential therapeutic target for control of inflammation and cancer.