Abstract. Leukocyte-derived proteases have long been considered simply degradative. However, emerging data raise possibilities of a complex and specific biologic role for these proteases in substrate processing and in signaling pathways within cells. This study reports that the release of neutrophilic and monocytic proteases, such as proteinase 3 (PR3) and human neutrophil elastase (HNE), can result in their entry into endothelial cells coincident with the activation of proapoptoticsignaling events through ERK, JNK, and p38 MAPK. Inhibition of JNK blocked PR3-induced apoptosis, and inhibition of p38 MAPK blocked PR3-and HNE-induced apoptosis, indicating that these pathways are required for activation of apoptosis. It is here shown that protease entry results in direct cleavage of p65 NF-B in the N-terminal region by PR3 and in the C-terminal region by HNE. This cleavage results in diminished transcriptional activity by NF-B as demonstrated by diminished levels of TNF-␣-induced IL-8 message in the presence of PR3 or HNE. Inhibition of caspases did not block the cleavage of p65 NF-B, and sequence analysis showed that the PR3 and HNE cleavage sites are unique with respect to reported caspase sites. The data demonstrate that PR3 and HNE have specific, fundamental roles in endothelial responses during inflammation. Upon entry, they can usurp the cell's control of its own fate by directly intervening into caspase cascades. This provides a unique mechanism of crosstalk between leukocytes and endothelial cells at sites of inflammation that impacts both cytokine networks and cell viability.

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Methotrexate (MTX) is an antimetabolite, folic acid antagonist that inhibits purine nucleotide production, DNA synthesis, and cellular proliferation. Despite widespread therapeutic uses, MTX remains a potent teratogen. Methotrexate embryopathy encompasses multiorgan system dysfunction, including intrauterine growth restriction as well as cardiac, craniofacial, renal, genital, and skeletal abnormalities. Effects of MTX exposure on fetal development continue to be described. This series of 4 patients with MTX-associated craniosynostosis represents the largest published association between prenatal MTX exposure and premature cranial suture closure.

OBJECTIVEIntracranial empyema is a life-threatening condition associated with a high mortality rate and residual deleterious neurological effects if not diagnosed and managed promptly. The authors present their institutional experience with immediate reimplantation of the craniotomy flap and clarify the success of this method in terms of cranial integrity, risk of recurrent infection, and need for secondary procedures.METHODSA retrospective analysis of patients admitted for management of intracranial empyema during a 19-year period (1997–2016) identified 33 patients who underwent emergency drainage and decompression with a follow-up duration longer than 6 months, 23 of whom received immediate bone replacement. Medical records were analyzed for demographic information, extent and location of the infection, bone flap size, fixation method, need for further operative intervention, and duration of intravenous antibiotics.RESULTSThe mean patient age at surgery was 8.7 ± 5.7 years and the infections were largely secondary to sinusitis (52.8%), with the most common location being the frontal/temporal region (61.3%). Operative intervention involved removal of a total of 31 bone flaps with a mean surface area of 22.8 ± 26.9 cm2. Nearly all (96.8%) of the bone flaps replaced at the time of the initial surgery were viable over the long term. Eighteen patients (78.3%) required a single craniotomy in conjunction with antibiotic therapy to address the infection, whereas the remaining 21.7% required more than 1 surgery. Partial bone flap resorption was noted in only 1 (3.2%) of the 31 successfully replaced bone flaps. This patient eventually had his bone flap removed and received a split-calvaria bone graft. Twenty-one patients (91.3%) received postoperative CT scans to evaluate bone integrity. The mean follow-up duration of the cohort was 43.9 ± 54.0 months.CONCLUSIONSThe results of our investigation suggest that immediate replacement and stabilization of the bone flap after craniectomy for drainage of intracranial empyemas has a low risk of recurrent infection and is a safe and effective way to restore bone integrity in most patients.