Intraoperative Infusion of Dextran Confers No Additional Benefit after Carotid Endarterectomy but Is Associated with Increased Perioperative Major Adverse Cardiac Events.

BACKGROUND: Intraoperative dextran infusion has been associated with reduction of an embolic risk in patients undergoing carotid endarterectomy (CEA). Nonetheless, dextran has been associated with adverse reactions, including anaphylaxis, hemorrhage, cardiac, and renal complications. Herein, we aimed to compare the perioperative outcomes of CEA stratified by the use of intraoperative dextran infusion using a large multiinstitutional dataset. METHODS: Patients undergoing CEA between 2008 and 2022 from the Vascular Quality Initiative database were reviewed. Patients were categorized by use of intraoperative dextran infusion, and demographics, procedural data, and in-hospital outcomes were compared. Logistic regression analysis was utilized to adjust for differences in patients while assessing the association between postoperative outcomes and intraoperative infusion of dextran. RESULTS: Of 140,893 patients undergoing CEA, 9,935 (7.1%) patients had intraoperative dextran infusion. Patients with intraoperative dextran infusion were older with lower rates of symptomatic stenosis (24.7% vs. 29.3%; P < 0.001) and preoperative use of antiplatelets, anticoagulants and statins. Additionally, they were more likely to have severe carotid stenosis (>80%; 49% vs. 45%; P < 0.001) and undergo CEA under general anesthesia (96.4% vs. 92.3%; P < 0.001), with a more frequent use of shunt (64.4% vs. 49.5%; P < 0.001). After adjustment, multivariable analysis showed that intraoperative dextran infusion was associated with higher odds of in-hospital major adverse cardiac events (MACE), including myocardial infarction [MI] (odds ratio [OR], 1.76, 95% confidence interval [CI]: 1.34-2.3, P < 0.001), congestive heart failure [CHF] (OR, 2.15, 95% CI: 1.67-2.77, P = 0.001), and hemodynamic instability requiring vasoactive agents (OR, 1.08, 95% CI: 1.03-1.13, P = 0.001). However, it was not associated with decreased odds of stroke (OR, 0.92, 95% CI: 0.74-1.16, P = 0.489) or death (OR, 0.88, 95% CI: 0.58-1.35, P = 0.554). These trends persisted even when stratified by symptomatic status and degree of stenosis. CONCLUSIONS: Intraoperative infusion of dextran was associated with increased odds of MACE, including MI, CHF, and persistent hemodynamic instability, without decreasing the risk of stroke perioperatively. Given these results, judicious use of dextran in patients undergoing CEA is recommended. Furthermore, careful perioperative cardiac management is warranted in select patients receiving intraoperative dextran during CEA.

Persistent damaged bases in DNA allow mutagenic break repair in Escherichia coli.

Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair. Pol IV is implied to compete with and replace high-fidelity DNA polymerases at the DSB-repair replisome, causing mutagenesis. We report that up-regulated Pol IV is not sufficient for mutagenic break repair (MBR); damaged bases in the DNA are also required, and that in starvation-stressed cells, these are caused by reactive-oxygen species (ROS). First, MBR is reduced by either ROS-scavenging agents or constitutive activation of oxidative-damage responses, both of which reduce cellular ROS levels. The ROS promote MBR other than by causing DSBs, saturating mismatch repair, oxidizing proteins, or inducing the SOS response or the general stress response. We find that ROS drive MBR through oxidized guanines (8-oxo-dG) in DNA, in that overproduction of a glycosylase that removes 8-oxo-dG from DNA prevents MBR. Further, other damaged DNA bases can substitute for 8-oxo-dG because ROS-scavenged cells resume MBR if either DNA pyrimidine dimers or alkylated bases are induced. We hypothesize that damaged bases in DNA pause the replisome and allow the critical switch from high fidelity to error-prone DNA polymerases in the DSB-repair replisome, thus allowing MBR. The data imply that in addition to the indirect stress-response controlled switch to MBR, a direct cis-acting switch to MBR occurs independently of DNA breakage, caused by ROS oxidation of DNA potentially regulated by ROS regulators.

Complex Esophageal Reconstruction Procedures Have Acceptable Outcomes Compared With Routine Esophagectomy.

BACKGROUND: Complex esophageal reconstruction (CER) is defined as restoring esophageal continuity in a previously operated field, using a nongastric conduit, or after esophageal diversion. This study compares the outcomes of CER with non-CER (NCER), which uses an undisturbed stomach for reconstruction. METHODS: This single-institution retrospective cohort study compares 75 CERs with 75 NCERs from 1995 to 2014 that were matched for cancer versus benign disease. Distributions of demographic characteristics, comorbidities, and complications were compared between CER and NCER. Odds of mortality at 30 and 90 days were calculated with logistic regression. Overall survival was illustrated with Kaplan-Meier method and Cox proportional hazards regression. RESULTS: Although patients were similar in age, sex, and preoperative comorbidities, more non-white patients underwent CER (p = 0.04). Most NCER patients had adenocarcinoma (44%) or Barrett's high-grade dysplasia (39%); most CER patients had other benign disease (44%) or squamous cell carcinoma (24%, p < 0.01). CER had statistically significantly higher rates of reoperation, pneumonia, infection, and gastrointestinal complications, and longer median length of stay than NCER. Odds of mortality for CER and NCER at 30 days (odds ratio [OR] 1.0, 95% CI: 0.1 to 16.3), 90 days (OR 2.6, 95% CI: 0.5 to 13.9) and overall (adjusted hazard ratio 1.56, 95% CI: 0.9 to 2.7) were not statistically significantly different. CONCLUSIONS: Compared with NCER, CER patients had higher rates of return to the operating room, more postoperative infections and gastrointestinal complications, and longer length of stay. However, 30-day, 90-day, and overall survival were similar. CER should be offered to patients with acceptable risks and anticipated long-term survival.

Roles of Nucleoid-Associated Proteins in Stress-Induced Mutagenic Break Repair in Starving Escherichia coli.

The mutagenicity of DNA double-strand break repair in Escherichia coli is controlled by DNA-damage (SOS) and general (RpoS) stress responses, which let error-prone DNA polymerases participate, potentially accelerating evolution during stress. Either base substitutions and indels or genome rearrangements result. Here we discovered that most small basic proteins that compact the genome, nucleoid-associated proteins (NAPs), promote or inhibit mutagenic break repair (MBR) via different routes. Of 15 NAPs, H-NS, Fis, CspE, and CbpA were required for MBR; Dps inhibited MBR; StpA and Hha did neither; and five others were characterized previously. Three essential genes were not tested. Using multiple tests, we found the following: First, Dps, which reduces reactive oxygen species (ROS), inhibited MBR, implicating ROS in MBR. Second, CbpA promoted F' plasmid maintenance, allowing MBR to be measured in an F'-based assay. Third, Fis was required for activation of the SOS DNA-damage response and could be substituted in MBR by SOS-induced levels of DinB error-prone DNA polymerase. Thus, Fis promoted MBR by allowing SOS activation. Fourth, H-NS represses ROS detoxifier sodB and was substituted in MBR by deletion of sodB, which was not otherwise mutagenic. We conclude that normal ROS levels promote MBR and that H-NS promotes MBR by maintaining ROS. CspE positively regulates RpoS, which is required for MBR. Four of five previously characterized NAPs promoted stress responses that enhance MBR. Hence, most NAPs affect MBR, the majority via regulatory functions. The data show that a total of six NAPs promote MBR by regulating stress responses, indicating the importance of nucleoid structure and function to the regulation of MBR and of coupling mutagenesis to stress, creating genetic diversity responsively.

Comparison of immune responses and protective efficacy of intranasal prime-boost immunization regimens using adenovirus-based and CpG/HH2 adjuvanted-subunit vaccines against genital Chlamydia muridarum infection.

An efficacious Chlamydia vaccine is urgently needed to control Chlamydia infections. Heterologous prime-boost vaccination regimens are emerging as a promising strategy for preventing intracellular viral and bacterial infections. However, it remains to be determined if this regimen would be a feasible and effective approach for Chlamydia infection. In this study, we examined the immune response and the protective efficacy induced by various vaccination regimens using a recombinant adenovirus vector expressing the Chlamydia antigen CPAF (AdCPAF) and recombinant CPAF (rCPAF) subunit vaccines formulated with CpG oligodeoxynucleotides and/or a synthetic immunomodulatory peptide HH2 as adjuvants. A single dose of AdCPAF stimulated potent antibody production but weak cellular immune responses in mice. A booster rCPAF vaccine formulated with both CpG and HH2, but not CpG alone or HH2 alone, showed robust adjuvant effects on induction of Th1-biased cellular immune responses in mice primed with AdCPAF. In contrast, a homologous regimen using rCPAF/CpG/HH2 subunit vaccine for both priming and boosting induced a weak antibody response, but potent cellular immunity with a mixed Th1/Th17 profile. Despite the disparities observed in humoral and cellular immune responses, both the heterologous and homologous prime-boost regimens conferred significant immune protection against genital Chlamydia muridarum challenge in C3H/HeN and BALB/c mice.

Global chromosomal structural instability in a subpopulation of starving Escherichia coli cells.

Copy-number variations (CNVs) constitute very common differences between individual humans and possibly all genomes and may therefore be important fuel for evolution, yet how they form remains elusive. In starving Escherichia coli, gene amplification is induced by stress, controlled by the general stress response. Amplification has been detected only encompassing genes that confer a growth advantage when amplified. We studied the structure of stress-induced gene amplification in starving cells in the Lac assay in Escherichia coli by array comparative genomic hybridization (aCGH), with polymerase chain reaction (pcr) and DNA sequencing to establish the structures generated. About 10% of 300 amplified isolates carried other chromosomal structural change in addition to amplification. Most of these were inversions and duplications associated with the amplification event. This complexity supports a mechanism similar to that seen in human non-recurrent copy number variants. We interpret these complex events in terms of repeated template switching during DNA replication. Importantly, we found a significant occurrence (6 out of 300) of chromosomal structural changes that were apparently not involved in the amplification event. These secondary changes were absent from 240 samples derived from starved cells not carrying amplification, suggesting that amplification happens in a differentiated subpopulation of stressed cells licensed for global chromosomal structural change and genomic instability. These data imply that chromosomal structural changes occur in bursts or showers of instability that may have the potential to drive rapid evolution.

Coating single-walled carbon nanotubes with phospholipids.

Single-walled carbon nanotubes (SWNTs), being hydrophobic by nature, aggregate in water to form large bundles. However, isolated SWNTs possess unique physical and chemical properties that are desirable for sensing and biological applications. Conventionally isolated SWNTs can be obtained by wrapping the tubes with biopolymers or surfactants. The binding modes proposed for these solubilization schemes, however, are less than comprehensive. Here we characterize the efficacies of solubilizing SWNTs through various types of phospholipids and other amphiphilic surfactants. Specifically, we demonstrate that lysophospholipids, or single-chained phospholipids offer unprecedented solubility for SWNTs, while double-chained phospholipids are ineffective in rendering SWNTs soluble. Using transmission electron microscopy (TEM) we show that lysophospholipids wrap SWNTs as striations whose size and regularity are affected by the polarity of the lysophospholipids. We further show that wrapping is only observed when SWNTs are in the lipid phase and not the vacuum phase, suggesting that the environment has a pertinent role in the binding process. Our findings shed light on the debate over the binding mechanism of amphiphilic polymers and cylindrical nanostructures and have implications on the design of novel supramolecular complexes and nanodevices.