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Giardia lamblia is an anaerobic aerotolerant eukaryotic parasite of the intestines. It is believed to have diverged early from eukarya during evolution and is thus lacking in many of the typical eukaryotic organelles and biochemical pathways. Most conspicuously, mitochondria and the associated machinery of oxidative phosphorylation are absent; instead, energy is derived from substrate-level phosphorylation. Here, the 1.75 Å resolution crystal structure of G. lamblia aldose reductase heterologously expressed in Escherichia coli is reported. As in other oxidoreductases, G. lamblia aldose reductase adopts a TIM-barrel conformation with the NADP+-binding site located within the eight β-strands of the interior. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis belongs to a large family of soil bacteria which can degrade a remarkably broad range of organic compounds and utilize them as carbon, nitrogen and energy sources. It has been proposed that a variety of mycobacteria can subsist on alternative carbon sources during latency within an infected human host, with the help of enzymes such as nitrilotriacetate monooxygenase (NTA-Mo). NTA-Mo is a member of a class of enzymes which consist of two components: A and B. While component A has monooxygenase activity and is responsible for the oxidation of the substrate, component B consumes cofactor to generate reduced flavin mononucleotide, which is required for component A activity. NTA-MoB from M. thermoresistibile, a rare but infectious close relative of M. tuberculosis which can thrive at elevated temperatures, has been expressed, purified and crystallized. The 1.6 Å resolution crystal structure of component B of NTA-Mo presented here is one of the first crystal structures determined from the organism M. thermoresistibile. The NTA-MoB crystal structure reveals a homodimer with the characteristic split-barrel motif typical of flavin reductases. Surprisingly, NTA-MoB from M. thermoresistibile contains a C-terminal tail that is highly conserved among mycobacterial orthologs and resides in the active site of the other protomer. Based on the structure, the C-terminal tail may modulate NTA-MoB activity in mycobacteria by blocking the binding of flavins and NADH. [ABSTRACT FROM AUTHOR]

Normotensive adults on low-sodium, weight-loss, and control diets recorded preferences and perceived saltiness for sodium chloride (NaCl) added to cream soup at intervals over 1 yr. Reduction in sodium intake and excretion accompanied a shift in preference toward less salt: preferred concentrations by ad libitum salting declined from 0.72% at the onset to 0.33% NaCl at week 24; hedonic scores for high concentrations of NaCl decreased significantly while scores for low concentrations increased. After 3 mo of sodium restriction, NaCl preferences readjusted to a lower level: ad libitum additions of NaCl were similar after 13, 24, and 52 wk. Less hedonic variation was observed among controls than among Na-restricted groups. The weight-loss group showed increased liking for mid-range NaCl levels. Mechanisms underlying preference changes, including physiological, behavioral, and context effects, may provide insights into maintenance of low-sodium diets for treatment and prevention of hypertension. [ABSTRACT FROM AUTHOR]

We describe an unusual case of spontaneous spiral dissection of a LIMA-LAD bypass graft presenting with an acute coronary syndrome. This complex lesion was treated percutaneously with multiple coronary stents. [ABSTRACT FROM AUTHOR]

Management of in-stent restenosis has become a significant challenge in interventional cardiology. The results of balloon angioplasty have been disappointing due to the high recurrence of restenosis at follow-up. Debulking of the restenotic tissue within the stents using directional coronary atherectomy (DCA) may offer a therapeutic advantage. We report the immediate clinical and angiographic outcomes and long-term clinical follow-up results of 45 patients (46 lesions), mean age 63+/-12 years, 73% men, with a mean reference diameter of 2.9+/-0.6 mm, treated with DCA for symptomatic Palmaz-Schatz in-stent restenosis. DCA was performed successfully in all 46 lesions and resulted in a postprocedural minimal luminal diameter of 2.7+/-0.7 mm and a residual diameter stenosis of 17+/-10%. There were no in-hospital deaths, Q-wave myocardial infarctions, or emergency coronary artery bypass surgeries. Four patients (9%) suffered a non-Q-wave myocardial infarction. Target lesion revascularization was 28.3% at a mean follow-up of 10+/-4.6 months. Kaplan-Meier event-free survival (freedom from death, myocardial infarction, and repeat target lesion revascularization) was 71.2% and 64.7% at 6 and 12 months after DCA, respectively. Thus, DCA is safe and efficacious for the treatment of Palmaz-Schatz in-stent restenosis. It results in a large postprocedural minimal luminal diameter and a low rate of both target lesion revascularization and combined major clinical events at follow-up. [ABSTRACT FROM AUTHOR]

The Legionella pneumophila Dot/Icm type IVB secretion system (T4BSS) is a large, multisubunit complex that exports a vast array of substrates into eukaryotic host cells. DotO, a distant homolog of the T4ASS ATPase VirB4, associates with the bacterial inner membrane despite lacking hydrophobic transmembrane domains. Employing a genetic approach, we found DotO's membrane association is mediated by three inner-membrane Dot/Icm components, IcmT, and a combined DotJ-DotI complex (referred to as DotJI). Although deletion of icmT or dotJI individually does not affect DotO's membrane association, the simultaneous inactivation of all three genes results in increased amounts of soluble DotO. Nevertheless, deleting each receptor separately profoundly affects positioning of DotO, disrupting its link with the Dot/Icm complex at the bacterial poles, rendering the receptors nonredundant. Furthermore, a collection of dotO point mutants that we isolated established that DotO's N-terminal domain interacts with the membrane receptors and is involved in dimerization, whereas DotO's C-terminal ATPase domain primarily contributes to the protein's formation of oligomers. Modeling data revealed the complex interaction between DotO and its receptors is responsible for formation of DotO's unique "hexamer of dimers" configuration, which is a defining characteristic of VirB4 family members., Competing Interests: Competing interests statement:The authors declare no competing interest.

PEGylated branched polyethylenimine (PEG-BPEI) has antibacterial and antibiofilm properties. Exposure to PEG-BPEI through serial passage leads to resistant P. aeruginosa strains. The minimum inhibitory concentration (MIC) of 600 Da BPEI and PEGylated 600 Da BPEI (PEG-BPEI) in the wild-type PAO1 strain is 16 μg/ml while, after 15 serial passages, the MIC increased to 1024 μg/mL. An additional 15 rounds of serial passage in the absence of BPEI or PEG-BPEI did not change the 1024 μg/mL MIC. Gentamicin, Neomycin, and Tobramycin, cationic antibiotics that inhibit protein synthesis, have a 16-32 fold reduction of MIC values in PEG350-BPEI resistant strains, suggesting increased permeation. The influx of these antibiotics occurs using a self-mediated uptake mechanism, suggesting changes to the outer membrane Data show that resistance causes changes in genes related to outer membrane lipopolysaccharide (LPS) assembly. Mutations were noted in the gene coding for the polymerase Wzy that participates in the assembly of the O-antigen region. Other mutations were noted with wbpE and wbpI of the Wbp pathway responsible for the enzymatic synthesis of ManNAc(3NAc)A in the LPS of P. aeruginosa. These changes suggest that an altered gene product could lead to PEG-BPEI resistance. Nevertheless, the increased susceptibility to aminoglycosides could prevent the emergence of PEG-BPEI resistant bacterial populations., (© 2024 Wiley-VCH GmbH.)

Background: Spontaneous pancreatic portal vein fistula (PPVF) - a rare complication of pancreatic inflammation - varies widely in presentation and means of diagnosis but has been previously associated with bleeding complications and mortality. A systematic review of published literature was performed to assess the frequency of outcomes., Methods: A search of electronic databases (PubMed, Ovid MEDLINE, Scopus, EMBASE, gray literature) resulted in 1667 relevant unique manuscripts; 52 met inclusion criteria., Results: A total of 74 unique (male n = 47, 63.5 %) patients were included. Mean age was 53.5 (±11.9) years. History of alcohol use was reported in 55 (74.3 %). Underlying chronic pancreatitis (CP) was present in 49 (66.2 %). In cases where presenting symptoms were reported (n = 57, 77.4 %), the most frequent were abdominal pain (63.5 %), weight loss (14.9 %), rash (12.2 %), nausea/vomiting (12.2 %), and polyarthritis (9.5 %). Computed tomography was the most common imaging modality used to confirm the diagnosis (n = 20, 27.0 %), followed by magnetic resonance cholangiopancreatography (n = 14, 18.9 %). Portal vein thrombosis was reported in 57 (77.0 %), and bleeding events (luminal, variceal, or intra-pseudocyst) were reported in 13(17.6 %) patients. Younger age was associated with higher risk of bleeding events. Mortality was reported in 12 (16.2 %) patients at any time during follow up. Older age and polyarthritis at presentation were associated with mortality., Conclusions: PPVF is a rare and potentially fatal condition, though rates of bleeding complication and death were relatively low in this population. High-quality observational studies are needed to better understand the pathophysiology and natural history of this diagnosis., Competing Interests: Declaration of competing interest AEP: Board Member, National Pancreas Foundation. All other authors declare no relevant conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Competing Interests: Disclosure All authors disclosed no financial relationships. Commentary The LAMS was initially proposed for the management of peripancreatic fluid collections, but its use has now been expanded to a variety of indications such as refractory GI luminal strictures. The technical success of LAMS for the treatment of stricture has been ≤98.6% in the literature. The short (10-mm) saddle length LAMS is ideal for refractory short-segment GI luminal strictures. The wide bilateral anchoring flanges of the LAMS provide a built-in antimigratory mechanism, decreasing the migration risk. However, the delivery catheter of the LAMS, with a catheter working length of 138 mm, is compatible only with echoendoscopes and therapeutic upper endoscopes. As these authors mention, LAMSs could be deployed ex vivo and backloaded within the working channel of a colonoscope or an enteroscope, making it available for the management of GI luminal strictures in any location that the colonoscope or enteroscope can reach, no matter how deep or far! The key to success is “twisting” the flanges to completely collapse one end. After that, the collapsed end of the LAMS can be pulled backward into the working channel by use of a “large” biopsy forceps. The LAMS is an ideal alternative for serial balloon dilation for the management of short distant luminal strictures, eliminating the need for multiple procedures. The LAMS, although effective, is associated with the risk of bleeding, stent migration, perforation, and de-novo stricture formation at the site of the flanges. Stent migration has been reported in ≤40% of cases. Ideally, it is better not to leave the LAMS in >4 weeks to prevent any possible adverse events that may arise. Tara Keihanian, MD, MPH, Assistant Professor, Division of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, Texas, USA Mohamed O. Othman, MD, GIE Senior Associate Editor

Colorectal cancer (CRC) is the third most common cancer in the United States. Recent epidemiological evidence demonstrates an increasing incidence of young-onset CRC cases, defined as CRC cases in individuals 50 years old or younger. Studies have established that alterations in both the WNT and TGF-Beta signaling pathways have contributed to CRC development. While this is well understood, the comprehensive analysis of WNT and TGF-Beta pathway alterations in young-onset CRC cases has yet to be investigated. Here, we conducted a comprehensive bioinformatics analysis of mutations associated with each of the WNT and TGF-Beta signaling pathways according to age (≤ 50 years old versus > 50 years old) utilizing published genomic data from the cBioPortal. Chi-square results demonstrated no significant difference in WNT alterations between young-onset CRC and those > 50 years old. However, across all age groups, WNT alterations were frequently found in rectal cancers. We also found that WNT alterations were associated with better outcomes. The mutations associated with TGF-beta were observed at a higher rate in older CRC patients when compared to those ≤ 50 years old. Additionally, these mutations were found more frequently in colon primaries., (© 2024. The Author(s).)

The innate immune system is an evolutionarily conserved pathogen recognition mechanism that serves as the first line of defense against tissue damage or pathogen invasion. Unlike the adaptive immunity that recruits T-cells and specific antibodies against antigens, innate immune cells express pathogen recognition receptors (PRRs) that can detect various pathogen-associated molecular patterns (PAMPs) released by invading pathogens. Microbial molecular patterns, such as lipopolysaccharide (LPS) from Gram-negative bacteria, trigger signaling cascades in the host that result in the production of pro-inflammatory cytokines. LPS stimulation produces a strong immune response and excessive LPS signaling leads to dysregulation of the immune response. However, dysregulated inflammatory response during wound healing often results in chronic non-healing wounds that are difficult to control. In this work, we present data demonstrating partial neutralization of anionic LPS molecules using cationic branched polyethylenimine (BPEI). The anionic sites on the LPS molecules from Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) are the lipid A moiety and BPEI binding create steric factors that hinder the binding of PRR signaling co-factors. This reduces the production of pro-inflammatory TNF-α cytokines. However, the anionic sites of Pseudomonas aeruginosa (P. aeruginosa) LPS are in the O-antigen region and subsequent BPEI binding slightly reduces TNF-α cytokine production. Fortunately, BPEI can reduce TNF-α cytokine expression in response to stimulation by intact P. aeruginosa bacterial cells and fungal zymosan PAMPs. Thus low-molecular weight (600 Da) BPEI may be able to counter dysregulated inflammation in chronic wounds and promote successful repair following tissue injury., (© 2024 Wiley-VCH GmbH.)

Background and Aims: The pathways and metabolites that contribute to residual cardiovascular disease risks are unclear. Low-calorie sweeteners are widely used sugar substitutes in processed foods with presumed health benefits. Many low-calorie sweeteners are sugar alcohols that also are produced endogenously, albeit at levels over 1000-fold lower than observed following consumption as a sugar substitute., Methods: Untargeted metabolomics studies were performed on overnight fasting plasma samples in a discovery cohort (n = 1157) of sequential stable subjects undergoing elective diagnostic cardiac evaluations; subsequent stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses were performed on an independent, non-overlapping validation cohort (n = 2149). Complementary isolated human platelet, platelet-rich plasma, whole blood, and animal model studies examined the effect of xylitol on platelet responsiveness and thrombus formation in vivo. Finally, an intervention study was performed to assess the effects of xylitol consumption on platelet function in healthy volunteers (n = 10)., Results: In initial untargeted metabolomics studies (discovery cohort), circulating levels of a polyol tentatively assigned as xylitol were associated with incident (3-year) major adverse cardiovascular event (MACE) risk. Subsequent stable isotope dilution LC-MS/MS analyses (validation cohort) specific for xylitol (and not its structural isomers) confirmed its association with incident MACE risk [third vs. first tertile adjusted hazard ratio (95% confidence interval), 1.57 (1.12-2.21), P < .01]. Complementary mechanistic studies showed xylitol-enhanced multiple indices of platelet reactivity and in vivo thrombosis formation at levels observed in fasting plasma. In interventional studies, consumption of a xylitol-sweetened drink markedly raised plasma levels and enhanced multiple functional measures of platelet responsiveness in all subjects., Conclusions: Xylitol is associated with incident MACE risk. Moreover, xylitol both enhanced platelet reactivity and thrombosis potential in vivo. Further studies examining the cardiovascular safety of xylitol are warranted., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Purpose: In 2013, afatinib was approved for non-small-cell lung cancer with subsequent indication expansion. We investigated published afatinib clinical trials to assess risk and benefit profiles for the drug in its approved indication of non-small-cell lung cancer as well as in off-label uses. Previous literature demonstrates excessive patient burden and limited benefit as afatinib has spread into more indications. A trial analysis is needed to establish efficacy and risk., Methods: In this investigation, we screened literature databases and clinical trial registries for trials of afatinib as monotherapy or in combination interventions for cancer treatment. We extracted participant demographics, adverse event characteristics, as well as clinical and surrogate endpoints for each trial. Studies were deemed positive, negative, or indeterminate based on their achieving of primary endpoints as well as their safety., Results: Our search yielded 2444 articles; we excluded 2352 articles for a final inclusion of 92 trials of 8859 patients. Our sample had 49 (53%) positive trials, 27 (29%) negative trials, and 16 (17%) indeterminate trials. The most common off-label indications for afatinib were breast cancer and squamous cell carcinoma of head and neck. The median OS for all trials was 8.4 months, median PFS 3.4 months, and the total ORR was 29.6%. Our study found that trials performed in disease states beyond the initial indications were largely negative with little patient benefit. The adverse events within our trial sample appear to be in line with expectations for toxicity., Implications: These results are consistent with other studies that present similar findings, such as in Carlisle et al which indicate limited efficacy in nonapproved indications. Future trials should keep this potential evidence and patient burden in mind before initiation of those trials. This study contributes to the understanding of afatinib's risk-benefit profile across many clinical applications., Competing Interests: Declaration of competing interest VP reports research funding from Arnold Ventures; royalties from Johns Hopkins Press, Medscape, and MedPage; honoraria from GrandRounds/lectures from universities, medical centers, nonprofits, professional societies, YouTube, and Substack; consulting from UnitedHealthcare and OptumRX; speaking fees from Evicore. Plenary Session podcast has Patreon backers. MV reports receipt of funding from the National Institute on Drug Abuse, the National Institute on Alcohol Abuse and Alcoholism, the U.S. Office of Research Integrity, Oklahoma Center for Advancement of Science and Technology, and internal grants from Oklahoma State University Center for Health Sciences—all outside of the present work. All other authors have nothing to report., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Innate immunity has considerable specificity and can discriminate between individual species of microbes. In this regard, pathogens are "seen" as dangerous to the host and elicit an inflammatory response capable of destroying the microbes. This immune discrimination is achieved by toll-like receptors on host cells recognizing pathogens, such as Staphylococcus aureus , and microbe-specific pathogen-associated molecular pattern (PAMP) molecules, such as lipoteichoic acid (LTA). PAMPs impede wound healing by lengthening the inflammatory phase of healing and contributing to the development of chronic wounds. Preventing PAMPs from triggering the release of inflammatory cytokines will counteract the dysregulation of inflammation. Here, we use ELISA to evaluate the use of cationic molecules branched polyethylenimine (BPEI), PEGylated BPEI (PEG-BPEI), and polymyxin-B to neutralize anionic LTA and lower levels of TNF-α cytokine release from human THP-1 monocytes in a concentration-dependent manner. Additional data collected with qPCR shows that BPEI and PEG-BPEI reduce the expression profile of the TNF-α gene. Similar effects are observed for the neutralization of whole-cell S. aureus bacteria. In vitro cytotoxicity data demonstrate that PEGylation lowers the toxicity of PEG-BPEI (IC 50 = 2661 μm) compared to BPEI (IC 50 = 853 μM) and that both compounds are orders of magnitude less toxic than the cationic antibiotic polymyxin-B (IC 50 = 79 μM). Additionally, the LTA neutralization ability of polymyxin-B is less effective than BPEI or PEG-BPEI. These properties of BPEI and PEG-BPEI expand their utility beyond disabling antibiotic resistance mechanisms and disrupting S. aureus biofilms, providing additional justification for developing these agents as wound healing therapeutics. The multiple mechanisms of action for BPEI and PEG-BPEI are superior to current wound treatment strategies that have a single modality., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Despite intensive preventive cardiovascular disease (CVD) efforts, substantial residual CVD risk remains even for individuals receiving all guideline-recommended interventions. Niacin is an essential micronutrient fortified in food staples, but its role in CVD is not well understood. In this study, untargeted metabolomics analysis of fasting plasma from stable cardiac patients in a prospective discovery cohort (n = 1,162 total, n = 422 females) suggested that niacin metabolism was associated with incident major adverse cardiovascular events (MACE). Serum levels of the terminal metabolites of excess niacin, N1-methyl-2-pyridone-5-carboxamide (2PY) and N1-methyl-4-pyridone-3-carboxamide (4PY), were associated with increased 3-year MACE risk in two validation cohorts (US n = 2,331 total, n = 774 females; European n = 832 total, n = 249 females) (adjusted hazard ratio (HR) (95% confidence interval) for 2PY: 1.64 (1.10-2.42) and 2.02 (1.29-3.18), respectively; for 4PY: 1.89 (1.26-2.84) and 1.99 (1.26-3.14), respectively). Phenome-wide association analysis of the genetic variant rs10496731, which was significantly associated with both 2PY and 4PY levels, revealed an association of this variant with levels of soluble vascular adhesion molecule 1 (sVCAM-1). Further meta-analysis confirmed association of rs10496731 with sVCAM-1 (n = 106,000 total, n = 53,075 females, P = 3.6 × 10 -18 ). Moreover, sVCAM-1 levels were significantly correlated with both 2PY and 4PY in a validation cohort (n = 974 total, n = 333 females) (2PY: rho = 0.13, P = 7.7 × 10 -5 ; 4PY: rho = 0.18, P = 1.1 × 10 -8 ). Lastly, treatment with physiological levels of 4PY, but not its structural isomer 2PY, induced expression of VCAM-1 and leukocyte adherence to vascular endothelium in mice. Collectively, these results indicate that the terminal breakdown products of excess niacin, 2PY and 4PY, are both associated with residual CVD risk. They also suggest an inflammation-dependent mechanism underlying the clinical association between 4PY and MACE., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Introduction: The US Food and Drug Administration (FDA) approved pembrolizumab for patients with unresectable or metastatic solid tumors with tumor mutational burden (TMB) of ≥ 10 mutations/megabase. However, the clinical implications of this universal cutoff of TMB ≥ 10 for patients with microsatellite stable (MSS) metastatic colorectal cancer (CRC) remain debatable., Areas Covered: In this review, we discuss the tissue agnostic approval of pembrolizumab, its efficacy, and clinical relevance in the management of patients with MSS CRC patients with high TMB (defined as TMB ≥ 10). We also elaborate on molecular subgroups of MSS CRC that influence the immune checkpoint inhibitor (ICI) response for patients with MSS CRC, including pathogenic POLE and POLD1 mutations associated with ultramutated tumors., Expert Opinion: Patients with microsatellite stable CRC with TMB ≥ 10 without POLE and POLD1 mutations may not significantly benefit from immune checkpoint inhibitors therapy. Predetermined cutoff TMB ≥ 10 mutation per MB does not seem to define a universal cutoff for the benefit of disease-agnostic ICI therapy, particularly for patients with MSS CRC. Patients with POLE/POLD1 mutations with MSS CRC represent a unique biological subgroup of MSS CRC with favorable responses to ICI therapy.

Carbapenem-resistant Enterobacteriaceae (CRE) are emerging pathogens that cause variety of severe infections. CRE evade antibiotic treatments because these bacteria produce enzymes that degrade a wide range of antibiotics including carbapenems and β-lactams. The formation of biofilms aggravates CRE infections, especially in a wound environment. These difficulties lead to persistent infection and non-healing wounds. This creates the need for new compounds to overcome CRE antimicrobial resistance and disrupt biofilms. Recent studies in our lab show that 600 Da branched polyethyleneimine (BPEI) and its derivative PEG350-BPEI can overcome antimicrobial resistance and eradicate biofilms in methicillin-resistant S. aureus, methicillin-resistant S. epidermidis, P. aeruginosa, and E. coli. In this study, the ability of 600 Da BPEI and PEG350-BPEI to eradicate carbapenem-resistant Enterobacteriaceae bacteria and their biofilms is demonstrated. We show that both BPEI and PEG350-BPEI have anti-biofilm efficacy against CRE strains expressing Klebsiella pneumoniae carbapenemases (KPCs) and metallo-β-lactamases (MBLs), such as New Delhi MBL (NDM-1). Furthermore, our results illustrate that BPEI affects planktonic CRE bacteria by increasing bacterial length and width from the inability to proceed with normal cell division processes. These data demonstrate the multi-functional properties of 600 Da BPEI and PEG350-BPEI to reduce biofilm formation and mitigate virulence in carbapenem-resistant Enterobacteriaceae., (© 2022 Wiley-VCH GmbH.)