A comprehensive study of risk factors for post-operative pneumonia following resection of meningioma.

BACKGROUND: Post-operative pneumonia (Pop) following meningioma surgery is the dominant systemic complication which could cause serious threats to patients. It is unclear whether hematological biochemical markers are independently associated with the Pop. This study attempted to perform a more comprehensive study of taking both clinical factors and hematological biomarkers into account to promote the management of patients after meningioma surgery. METHODS: We collected clinical and hematological parameters of 1156 patients undergoing meningioma resection from January 2009 to January 2013. According to whether the symptoms of pneumonia had manifested,patients were divided into the Pop group and the Non-Pop group. We analyzed the distinctions of clinical factors between the two groups. We successively performed univariate and multivariate regression analysis to identify risk factors independently associated with the Pop. RESULTS: 4.4% patients infected with the Pop (51 of 1156). The median age at diagnosis of the Pop patients was significantly older than the Non-Pop group (p = 0.002). There were strike distinctions of post-operative hospital stays between two groups, with 21 days and 7 days each (p < 0.001). On multivariate analysis, tumor relapse (p < 0.001), skull base lesions (p = 0.001), intra-operative blood transfusion (p = 0.018) and cardiovascular diseases (p = 0.001) were linked with increased risk of the Pop following meningioma resection. For hematological biochemical markers, it was the factor of Red blood cell distribution width-standard deviation (RDW-SD) (OR 5.267, 95%CI 1.316, 21.078; p = 0.019) and Neutrophils lymphocytes ratio (NLR) (OR 2.081, 95%CI 1.063, 4.067; p = 0.033) that could appreciably predict the Pop. CONCLUSIONS: Apart from tumor recurrence, localizations, intra-operative blood transfusion and cardiovascular diseases are independent risk factors for the Pop. We initially found hematological RDW-SD and NLR are also important predictors.

The double catalytic triad, Cys25-His159-Asp158 and Cys25-His159-Asn175, in papain catalysis: role of Asp158 and Asn175.

The 1.65 A X-ray structure of papain, which exhibits a Cys25-His159-Asn175 triad, does not correspond to the catalytically active ion pair state since Cys25 is oxidized to cysteic acid and His159 is predominantly neutral. Thus, stochastic boundary molecular dynamics simulations starting from the 1.65 A X-ray structure of papain have been performed for Cys25 and His159 in the SH-ImH+, SH-Im, S(-)-ImH+ and S(-)-Im states and for Asp158 mutated to Asn, Glu and Gly in the ion pair state. By comparing the resulting averaged structures and analyzing the trajectories of certain interatomic distances, important differences in the active-site geometry of papain have been found. In particular, the initial Cys25(S-)-His159(ImH+)-Asn175(C = O) triad found in the X-ray structure is retained in all the structures except the wild type and Asp158-->Asn ion pair states where there is a conformational transition to form the triad, Cys25(S-)-His159(ImH+)-Asp158(COO-). Both triads, Cys25(S-)-His159(ImH+)-Asp158(COO-) and Cys25(S-)-His159(ImH+)-Asn175(C = O) are postulated to participate in catalysis and their roles are discussed. Thus, catalysis does not take place from a single steric position but a two-state mechanism.