نتایج جستجو برای: barrier to entry

تعداد نتایج: 10648314  

Journal: :Immunity 2009
Richard Daneman Maria Rescigno

In order to protect itself from a diverse set of environmental pathogens and toxins, the body has developed a number of barrier mechanisms to limit the entry of potential hazards. Here, we compare two such barriers: the gut immune barrier, which is the primary barrier against pathogens and toxins ingested in food, and the blood-brain barrier, which protects the central nervous system from patho...

Journal: :Social Science Research Network 2021

Procuring authorities frequently use screening in order to mitigate risky bids. This study estimates the effect of bid and litigation on entry bidding using a unique data set highway construction procurement auctions Poland. The market exhibits method that ex post selects eligible offers. We demonstrate with an empirical model this disproportionately affects small firms creates barrier entry. O...

Journal: :Journal of virology 2002
Nancy Q Liu Albert S Lossinsky Waldemar Popik Xia Li Chandrasekhar Gujuluva Benjamin Kriederman Jaclyn Roberts Tatania Pushkarsky Michael Bukrinsky Marlys Witte Martin Weinand Milan Fiala

Brain microvascular endothelial cells (BMVECs) present an incomplete barrier to human immunodeficiency virus type 1 (HIV-1) neuroinvasion. In order to clarify the mechanisms of HIV-1 invasion, we have examined HIV-1 uptake and transcellular penetration in an in vitro BMVEC model. No evidence of productive infection was observed by luciferase, PCR, and reverse transcriptase assays. Approximately...

Journal: :American journal of physiology. Lung cellular and molecular physiology 2000
T M Moore N R Norwood J R Creighton P Babal G H Brough D M Shasby T Stevens

The present study evaluated the necessity of store-operated Ca(2+) entry in mediating thrombin-induced 20-kDa myosin light chain (MLC(20)) phosphorylation and increased permeability in bovine pulmonary artery endothelial cells (BPAECs). Thrombin (7 U/ml) and thapsigargin (1 microM) activated Ca(2+) entry through a common pathway in confluent BPAECs. Similar increases in MLC(20) phosphorylation ...

Journal: :American journal of physiology. Lung cellular and molecular physiology 1999
Troy Stevens Judy Creighton W Joseph Thompson

Pulmonary microvascular endothelial cells (PMVECs) form a more restrictive barrier to macromolecular flux than pulmonary arterial endothelial cells (PAECs); however, the mechanisms responsible for this intrinsic feature of PMVECs are unknown. Because cAMP improves endothelial barrier function, we hypothesized that differences in enzyme regulation of cAMP synthesis and/or degradation uniquely es...

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