Microcirculatory alterations in ischemia–reperfusion injury and sepsis: effects of activated protein C and thrombin inhibition

Experimental studies in ischemia–reperfusion and sepsis indicate that activated protein C (APC) has direct anti-inflammatory effects at a cellular level. In vivo, however, the mechanisms of action have not been characterized thus far. Intravital multifluorescence microscopy represents an elegant way of studying the effect of APC on endotoxin-induced leukocyte–endothelial-cell interaction and nutritive capillary perfusion failure. These studies have clarified that APC effectively reduces leukocyte rolling and leukocyte firm adhesion in systemic endotoxemia. Protection from leukocytic inflammation is probably mediated by a modulation of adhesion molecule expression on the surface of leukocytes and endothelial cells. Of interest, the action of APC and antithrombin in endotoxin-induced leukocyte–endothelial-cell interaction differs in that APC inhibits both rolling and subsequent firm adhesion, whereas antithrombin exclusively reduces the firm adhesion step. The biological significance of this differential regulation of inflammation remains unclear, since both proteins are capable of reducing sepsis-induced capillary perfusion failure. To elucidate whether the action of APC and antithrombin is mediated by inhibition of thrombin, the specific thrombin inhibitor hirudin has been examined in a sepsis microcirculation model. Strikingly, hirudin was not capable of protecting from sepsis-induced microcirculatory dysfunction, but induced a further increase of leukocyte–endothelial-cell interactions and aggravated capillary perfusion failure when compared with nontreated controls. Thus, the action of APC on the microcirculatory level in systemic endotoxemia is unlikely to be caused by a thrombin inhibition-associated anticoagulatory action

miR-221 Mediates Chemoresistance of Esophageal Adenocarcinoma by Direct Targeting of DKK2 Expression

Background:Chemoresistance is a main obstacle to effective esophageal cancer (EC) therapy. We hypothesize that altered expression of microRNAs (miRNAs) play a role in EC cancer progression and resistance to 5-fluorouracil (5-FU) based chemotherapeutic strategies.Methods:Four pairs of esophageal adenocarcinoma (EAC) cell lines and corresponding 5-FU resistant variants were established. The expression levels of miRNAs previously shown to be involved in the general regulation of stem cell pathways were analyzed by qRT-PCR. The effects of selected miRNAs on proliferation, apoptosis, and chemosensitivity were evaluated both in vitro and in vivo. We identified a particular miRNA and analyzed its putative target genes in 14 pairs of human EC tumor specimens with surrounding normal tissue by qRT-PCR as well as Wnt pathway associated genes by immunohistochemistry in another 45 EAC tumor samples.Results:MiR-221 was overexpressed in 5-FU resistant EC cell lines as well as in human EAC tissue. DKK2 was identified as a target gene for miR-221. Knockdown of miR-221 in 5-FU resistant cells resulted in reduced cell proliferation, increased apoptosis, restored chemosensitivity, and led to inactivation of the Wnt/-catenin pathway mediated by alteration in DKK2 expression. Moreover, miR-221 reduction resulted in alteration of EMT-associated genes such as E-cadherin and vimentin as well as significantly slower xenograft tumor growth in nude mice. RT2 profiler analysis identified a substantial dysregulation of 4 Wnt/-catenin signaling and chemoresistance target genes as a result of miR-221 modulation: CDH1, CD44, MYC, and ABCG2.Conclusion:MiR-221 controls 5-FU resistance of EC partly via modulation of Wnt/-catenin-EMT pathways by direct targeting of DKK2 expression. MiR-221 may serve as a prognostic marker and therapeutic target for patients with 5-FU resistant EAC

On the cosmic ray bound for models of extragalactic neutrino production

We obtain the maximum diffuse neutrino intensity predicted by hadronic photoproduction models of the type which have been applied to the jets of active galactic nuclei or gamma ray bursts. For this, we compare the proton and gamma ray fluxes associated with hadronic photoproduction in extragalactic neutrino sources with the present experimental upper limit on cosmic ray protons and the extragalactic gamma ray background, employing a transport calculation of energetic protons traversing cosmic photon backgrounds. We take into account the effects of the photon spectral shape in the sources on the photoproduction process, cosmological source evolution, the optical depth for cosmic ray ejection, and discuss the possible effects of magnetic fields in the vicinity of the sources. For photohadronic neutrino sources which are optically thin to the emission of neutrons we find that the cosmic ray flux imposes a stronger bound than the extragalactic gamma ray background in the energy range between 10^5 GeV and 10^11 GeV, as previously noted by Waxman & Bahcall (1999). We also determine the maximum contribution from the jets of active galactic nuclei, using constraints set to their neutron opacity by gamma-ray observations. This present upper limit is consistent with the jets of active galactic nuclei producing the extragalactic gamma ray background hadronically, but we point out future observations in the GeV-to-TeV regime could lower this limit. We also briefly discuss the contribution of gamma ray bursts to ultra-high energy cosmic rays as it can be inferred from possible observations or limits on their correlated neutrino fluxes.Comment: 16 pages, includes 7 figures, using REVtex3.1, accepted for publication in Phys.Rev.D after minor revision

Pulmonary sclerosing hemangioma in a 21-year-old male with metastatic hereditary non-polyposis colorectal cancer: Report of a case

<p>Abstract</p> <p>Background</p> <p>Pulmonary sclerosing hemangioma (SH) is a rare tumor of the lung predominantly affecting Asian women in their fifth decade of life. SH is thought to evolve from primitive respiratory epithelium and mostly shows benign biological behavior; however, cases of lymph node metastases, local recurrence and multiple lesions have been described.</p> <p>Case Presentation</p> <p>We report the case of a 21-year-old Caucasian male with a history of locally advanced and metastatic rectal carcinoma (UICC IV; pT4, pN1, M1(hep)) that was eventually identified as having hereditary non-polyposis colorectal cancer (HNPCC, Lynch syndrome). After neoadjuvant chemotherapy followed by low anterior resection, adjuvant chemotherapy and metachronous partial hepatectomy, he was admitted for treatment of newly diagnosed bilateral pulmonary metastases. Thoracic computed tomography showed a homogenous, sharply marked nodule in the left lower lobe. We decided in favor of atypical resection followed by systematic lymphadenectomy. Histopathological analysis revealed the diagnosis of SH.</p> <p>Conclusions</p> <p>Cases have been published with familial adenomatous polyposis (FAP) and simultaneous SH. FAP, Gardner syndrome and Li-Fraumeni syndrome, however, had been ruled out in the present case. To the best of our knowledge, this is the first report describing SH associated with Lynch syndrome.</p