Closed Suction Drainage after Total Knee Arthroplasty with Concomitant Intravenous Tranexamic Acid Administration.

Drain use in total knee arthroplasty (TKA) remains controversial. Use has been associated with increased complications, particularly postoperative transfusion, infection, increased cost, and longer hospital stays. However, studies examining drain use were performed before widespread adoption of tranexamic acid (TXA), which markedly reduces transfusion without increasing venous thromboembolism events. We aim to investigate incidence of postoperative transfusion and 90-day return to the operating room (ROR) for hemarthrosis in TKA with use of drains and concomitant intravenous (IV) TXA. Primary TKAs from a single institution were identified from August 2012 to December 2018. Inclusion criteria were primary TKA, age 18 years and over where use of TXA, drains, anticoagulant, and pre- and postsurgical hemoglobin (Hb) were documented during the patient's admission. Primary outcomes were 90-day ROR specifically for hemarthrosis and rate of postoperative transfusion. A total of 2,008 patients were included. Sixteen patients required ROR, three of which were due to hemarthrosis. Drain output was statistically higher in the ROR group (269.3 vs. 152.4 mL, p = 0.05). Five patients required transfusion within 14 days (0.25%). Patients requiring transfusion had significantly lower presurgical Hb (10.2 g/dL, p = 0.01) and 24-hour postoperative Hb (7.7 g/dL, p < 0.001). Drain output between the transfusion and no transfusion groups varied significantly (p = 0.03), with transfusion patients having higher postoperative day 1 drain output of 362.6 mL and total drain output of 376.6 mL. In this series, postoperative drain use with concomitant weight-based IV TXA is shown to be safe and efficacious. We observed exceedingly low risk of postoperative transfusion compared with prior reports of drain use alone as well as preserved low rate of hemarthrosis that has previously been positively linked to drain use.

Characterization of a unique polysaccharide monooxygenase from the plant pathogen Magnaporthe oryzae.

Blast disease in cereal plants is caused by the fungus Magnaporthe oryzae and accounts for a significant loss in food crops. At the outset of infection, expression of a putative polysaccharide monooxygenase (MoPMO9A) is increased. MoPMO9A contains a catalytic domain predicted to act on cellulose and a carbohydrate-binding domain that binds chitin. A sequence similarity network of the MoPMO9A family AA9 showed that 220 of the 223 sequences in the MoPMO9A-containing cluster of sequences have a conserved unannotated region with no assigned function. Expression and purification of the full length and two MoPMO9A truncations, one containing the catalytic domain and the domain of unknown function (DUF) and one with only the catalytic domain, were carried out. In contrast to other AA9 polysaccharide monooxygenases (PMOs), MoPMO9A is not active on cellulose but showed activity on cereal-derived mixed (1→3, 1→4)-ß-D-glucans (MBG). Moreover, the DUF is required for activity. MoPMO9A exhibits activity consistent with C4 oxidation of the polysaccharide and can utilize either oxygen or hydrogen peroxide as a cosubstrate. It contains a predicted 3-dimensional fold characteristic of other PMOs. The DUF is predicted to form a coiled-coil with six absolutely conserved cysteines acting as a zipper between the two α-helices. MoPMO9A substrate specificity and domain architecture are different from previously characterized AA9 PMOs. The results, including a gene ontology analysis, support a role for MoPMO9A in MBG degradation during plant infection. Consistent with this analysis, deletion of MoPMO9A results in reduced pathogenicity.

An endogenous dAMP ligand in Bacillus subtilis class Ib RNR promotes assembly of a noncanonical dimer for regulation by dATP.

The high fidelity of DNA replication and repair is attributable, in part, to the allosteric regulation of ribonucleotide reductases (RNRs) that maintains proper deoxynucleotide pool sizes and ratios in vivo. In class Ia RNRs, ATP (stimulatory) and dATP (inhibitory) regulate activity by binding to the ATP-cone domain at the N terminus of the large α subunit and altering the enzyme's quaternary structure. Class Ib RNRs, in contrast, have a partial cone domain and have generally been found to be insensitive to dATP inhibition. An exception is the Bacillus subtilis Ib RNR, which we recently reported to be inhibited by physiological concentrations of dATP. Here, we demonstrate that the α subunit of this RNR contains tightly bound deoxyadenosine 5'-monophosphate (dAMP) in its N-terminal domain and that dATP inhibition of CDP reduction is enhanced by its presence. X-ray crystallography reveals a previously unobserved (noncanonical) α2 dimer with its entire interface composed of the partial N-terminal cone domains, each binding a dAMP molecule. Using small-angle X-ray scattering (SAXS), we show that this noncanonical α2 dimer is the predominant form of the dAMP-bound α in solution and further show that addition of dATP leads to the formation of larger oligomers. Based on this information, we propose a model to describe the mechanism by which the noncanonical α2 inhibits the activity of the B. subtilis Ib RNR in a dATP- and dAMP-dependent manner.

Gas Phase Oxidation of Campholenic Aldehyde and Solution Phase Reactivity of its Epoxide Derivative.

The rate constant for the OH reaction with campholenic aldehyde (CA) was measured using the flow tube-chemical ionization mass spectrometry method with a relative rate kinetics technique and was found to be (6.54 ± 0.52) × 10-11 cm3 molecule-1 s-1 at 100 Torr pressure and 298 K. A mechanism for the formation of the observed products was developed for both NO-free and NO-present conditions. On the basis of measurements of the pressure dependent yields of the products, between 5 and 20% of the CA oxidation at atmospheric pressure is predicted to lead to campholenic aldehyde epoxide (CAE). The aqueous solution reaction rate constants for CAE were determined via NMR spectroscopy and were found to be (2.241 ± 0.036) × 10-5 s-1 for neutral conditions and 0.0989 ± 0.0053 M-1 s-1 for acid-catalyzed conditions at 298 K. The products of the CAE aqueous solution reaction were identified as an isomer of CAE and the aldehyde group hydrated form of this isomer. Unlike the isoprene-derived epoxide, IEPOX, a nucleophilic addition mechanism was not observed. On the basis of the rate constants determined for CA and CAE, it is likely that these species are reactive on atmospherically relevant time scales in the gas and aerosol phases, respectively. The results of the present study largely support a previous supposition that α-pinene-derived secondary organic aerosol may be influenced by the multiphase processing of various intermediate species, including those with epoxide functionality.