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Acetate esters comprise a wide range of products including fragrances and industrial solvents. Biosynthesis of esters offers a promising alternative to chemical synthesis because such routes use renewable carbohydrate resources and minimize the generation of waste. One biochemical method for ester formation relies on the ATF1 gene from Saccharomyces cerevisiae, which encodes alcohol-O-acyltransferase (AAT) which converts acetyl-CoA and an exogenously supplied alcohol into the ester. In this study, the formation of several acetate esters via AAT was examined in Escherichia coli chromosomally expressing citrate synthase variants, which create a metabolic bottleneck at acetyl-CoA. In shake flask cultures, variant strains generated more acetate esters than the strains expressing the wild-type citrate synthase. In a controlled bioreactor, E. coli GltA[A267T] generated 3.9 g propyl acetate in 13 h, corresponding to a yield of 0.155 g propyl acetate/g glucose, which is 18% greater than that obtained by the wild-type GltA control. These results demonstrate the ability of citrate synthase variants to redistribute carbon from central metabolism into acetyl-CoA-derived biochemicals.

Acetate esters comprise a wide range of products including fragrances and industrial solvents. Biosynthesis of esters offers a promising alternative to chemical synthesis because such routes use renewable carbohydrate resources and minimize the generation of waste. One biochemical method for ester formation relies on the ATF1 gene from Saccharomyces cerevisiae, which encodes alcohol-O-acyltransferase (AAT) which converts acetyl-CoA and an exogenously supplied alcohol into the ester. In this study, the formation of several acetate esters via AAT was examined in Escherichia coli chromosomally expressing citrate synthase variants, which create a metabolic bottleneck at acetyl-CoA. In shake flask cultures, variant strains generated more acetate esters than the strains expressing the wild-type citrate synthase. In a controlled bioreactor, E. coli GltA[A267T] generated 3.9 g propyl acetate in 13 h, corresponding to a yield of 0.155 g propyl acetate/g glucose, which is 18% greater than that obtained by the wild-type GltA control. These results demonstrate the ability of citrate synthase variants to redistribute carbon from central metabolism into acetyl-CoA-derived biochemicals. [ABSTRACT FROM AUTHOR]

Steroid hormone metabolism by the gut microbiome has multiple implications for mammalian physiology, but the underlying mechanisms and broader significance of this activity remains largely unknown. Here, we isolate a novel human gut bacterium, Clostridium steroidoreducens T strain HCS.1, that reduces cortisol, progesterone, testosterone, and related steroid hormones to 3β,5β-tetrahydrosteroid products. Through transcriptomics and heterologous enzyme profiling, we identify and biochemically characterize the C. steroidoreducens OsrABC reductive steroid hormone pathway. OsrA is a 3-oxo-Δ 1 -steroid hormone reductase that selectively targets the Δ 1 -bond present in synthetic steroid hormones, including the anti-inflammatory corticosteroids prednisolone and dexamethasone. OsrB is a promiscuous 3-oxo-Δ 4 -steroid hormone reductase that converts steroid hormones to 5β-dihydrosteroid intermediates. OsrC is a 3-oxo-5β-steroid hormone oxidoreductase that reduces 5β-intermediates to 3β,5β-tetrahydro products. We find that osrA and osrB homologs predict steroid hormone reductase activity in diverse gut bacteria and are enriched in Crohn's disease fecal metagenomes. These studies thus identify the basis of reductive steroid hormone metabolism in the gut and establish a link between inflammatory disease and microbial enzymes that deplete anti-inflammatory corticosteroids.

Sterols are ubiquitous membrane constituents that persist to a large extent in the environment due to their water insolubility and chemical inertness. Recently, an oxygenase-independent sterol degradation pathway was discovered in a cholesterol-grown denitrifying bacterium Sterolibacterium (S.) denitrificans. It achieves hydroxylation of the unactivated primary C26 of the isoprenoid side chain to an allylic alcohol via a phosphorylated intermediate in a four-step ATP-dependent enzyme cascade. However, this pathway is incompatible with the degradation of widely distributed steroids containing a double bond at C22 in the isoprenoid side chain such as the plant sterol stigmasterol. Here, we have enriched a prototypical delta-24 desaturase from S. denitrificans, which catalyzes the electron acceptor-dependent oxidation of the intermediate stigmast-1,4-diene-3-one to a conjugated (22,24)-diene. We suggest an α 4 β 4 architecture of the 440 kDa enzyme, with each subunit covalently binding an flavin mononucleotide cofactor to a histidyl residue. As isolated, both flavins are present as red semiquinone radicals, which can be reduced by stigmast-1,4-diene-3-one but cannot be oxidized even with strong oxidizing agents. We propose a mechanism involving an allylic radical intermediate in which two flavin semiquinones each abstract one hydrogen atom from the substrate. The conjugated delta-22,24 moiety formed allows for the subsequent hydroxylation of the terminal C26 with water by a heterologously produced molybdenum-dependent steroid C26 dehydrogenase 2. In conclusion, the pathway elucidated for delta-22 steroids achieves oxygen-independent hydroxylation of the isoprenoid side chain by bypassing the ATP-dependent formation of a phosphorylated intermediate., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Early detection of pulmonary complications can improve outcomes for patients with hematological malignancy (HM). For detecting lung injuries, lung ultrasound (LUS) images have been found to be of greater sensitivity than radiographic images. Our group performed a pilot study of LUS imaging to enhance early detection of pulmonary complications in HM patients. This prospective single-center feasibility study evaluated LUS for detecting pulmonary complications in 18 HM patients enrolled while hospitalized for a hematopoietic cell transplant (HCT) (concurrent-HCT group) or re-hospitalized for complications (post-HCT group). Serial LUS exams were performed and assigned a score from 0 to 5 based on pleural line, B-line, consolidation and pleural effusion features. Correlations between patients' clinical characteristics and LUS features were analyzed. Comparisons between the LUS and radiographic images were evaluated. In the concurrent-HCT patients (79 LUS exams), non-significant fluctuating findings were commonly identified, but one-third of the patients presented pathologic findings (LUS scores ≥ 3). In the post-HCT patients (29 LUS exams), LUS images revealed severe pathologic findings (LUS score = 5) in every patient and, compared with radiographic images, were more sensitive for detecting pleural effusions (p < 0.05). LUS can be routinely performed on hospitalized HM patients, allowing point-of-care early detection of pulmonary complications., Competing Interests: Conflict of interest disclosure The authors declare they have no conflicts of interest., (Copyright © 2022 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

This article contains raw and processed data related to research published by Vega et al. (2022). This complementary dataset provides further insight into the experimental validation of a single common carotid artery occlusion (CCAO) model upon pretreatment with pertussis toxin (PTX). We present data showing the extent of different PTX concentrations on neurological severity measured by Bederson score following CCAO. In addition, data indicate a protective effect of isoflurane on cerebral infarction and neurological deficits, as well as the consequences of PTX pretreatment on reperfusion after occlusion using time-of-flight magnetic resonance angiography. With these data, we aim to provide detailed experimental settings of this newly described model., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors. Published by Elsevier Inc.)

The course of COVID-19 has been shown to be worse in pregnant women compared with their non-pregnant counterparts. The aim of this study is to share our experience treating pregnant women with COVID-19 and to establish a cohort for future studies of the long-term effects of the disease. We reviewed medical records of all SARS-CoV-2-positive pregnant women who were treated at our hospital for any reason, be it COVID-19 related or not, between April 2020 and February 2021. We extracted data regarding medical history, course of pregnancy, delivery, and neonatal outcomes. A total of 193 SARS-CoV-2-positive pregnant women were treated at our establishment during the study period, half of which were asymptomatic. Sixteen were hospitalized for COVID-19 symptoms, the most common being fatigue/malaise (58%) and cough (48%). Three women required mechanical ventilation and extracorporeal membrane oxygenation treatment. One hundred forty-four SARS-CoV-2-positive women were delivered during the study period. Of them, 24 (17%) underwent induction of labor, and four (17%) were due to symptomatic COVID-19. One hundred fifteen (80%) experienced vaginal delivery, and 29 (20%) underwent cesarean delivery. Neonatal outcomes were favorable; only 2% of 5-min Apgar scores were < 7, and all umbilical cord pH levels were > 7.1. Six infants tested positive for SARS-CoV-2; they were all asymptomatic, and none required treatment for viral infection. COVID-19 during pregnancy is a disease with potential substantial adverse maternal and neonatal outcomes. There is still much unknown regarding the long-term effects of the disease on parturients and their offspring., (© 2022. Society for Reproductive Investigation.)

Quaternary carbon-containing compounds exist in natural and fossil oil-derived products and are used in chemical and pharmaceutical applications up to industrial scale. Due to the inaccessibility of the quaternary carbon atom for a direct oxidative or reductive attack, they are considered as persistent in the environment. Here, we investigated the unknown degradation of the quaternary carbon-containing model compound pivalate (2,2-dimethyl-propionate) in the denitrifying bacterium Thauera humireducens strain PIV-1 (formerly Thauera pivalivorans). We provide multiple evidence for a pathway comprising the activation to pivalyl-CoA and the carbon skeleton rearrangement to isovaleryl-CoA. Subsequent reactions proceed similar to the catabolic leucine degradation pathway such as the carboxylation to 3-methylglutaconyl-CoA and the cleavage of 3-methyl-3-hydroxyglutaryl-CoA to acetyl-CoA and acetoacetate. The completed genome of Thauera humireducens strain PIV-1 together with proteomic data was used to identify pivalate-upregulated gene clusters including genes putatively encoding pivalate CoA ligase and adenosylcobalamin-dependent pivalyl-CoA mutase. A pivalate-induced gene encoding a putative carboxylic acid CoA ligase was heterologously expressed, and its highly enriched product exhibited pivalate CoA ligase activity. The results provide the first experimental insights into the biodegradation pathway of a quaternary carbon-containing model compound that serves as a blueprint for the degradation of related quaternary carbon-containing compounds., (© 2022 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.)

Background: The COVID-19 pandemic is an ongoing global healthcare crisis that negatively affects pregnant women. Although patients with an acute infection during pregnancy have been widely studied, information regarding labor and delivery while infected is sparse. The aim of the study was to ascertain maternal, obstetrical, and perinatal outcomes of women who gave birth while infected with SARS-CoV-2., Methods: Patients diagnosed with COVID-19 during pregnancy at a tertiary medical center in 4/20-2/21 were identified by a retrospective database search. Those with an active intrapartum SARS-CoV-2 infection were compared with those who recovered at least 10 days before labor and delivery., Results: Of the 176 women included in the study, 84 had a SARS-CoV-2 infection at the time of delivery and 92 had recovered from the infection. There was no statistically significant between-group difference in mean gestational age at delivery (39 weeks for both, p = 0.71) and overall rate of cesarean delivery (26.2% vs 17.4%, respectively, p = 0.35) or non-elective cesarean delivery (10.71% vs 4.34%, respectively, p = 0.48). In the active-infection group, the rate of severe disease was 2.4%, and of critical disease (with intensive care unit admission, mechanical ventilation, and ECMO), 3.6%, compared to zero for both in the recovered group. No differences were found between the groups in adverse perinatal outcomes., Conclusion: Delivery is safe and feasible in women with active SARS-CoV-2 infection. Nevertheless, we found a non-significant trend for more severe disease and for cesarean delivery and urgent cesarean delivery (for COVID-19-related indications) in women with an intrapartum SARS-CoV-2 infection., (© 2022. The Author(s).)

Aortic valve stenosis (AS) is the most frequent valve disease with relevant prognostic impact. Experimental model systems for AS are scarce and comprehensive imaging techniques to simultaneously quantify function and morphology in disease progression are lacking. Therefore, we refined an acute murine AS model to closely mimic human disease characteristics and developed a high-resolution magnetic resonance imaging (MRI) approach for simultaneous in-depth analysis of valvular, myocardial as well as aortic morphology/pathophysiology to identify early changes in tissue texture and critical transition points in the adaptive process to AS. AS was induced by wire injury of the aortic valve. Four weeks after surgery, cine loops, velocity, and relaxometry maps were acquired at 9.4 T to monitor structural/functional alterations in valve, aorta, and left ventricle (LV). In vivo MRI data were subsequently validated by histology and compared to echocardiography. AS mice exhibited impaired valve opening accompanied by significant valve thickening due to fibrotic remodelling. While control mice showed bell-shaped flow profiles, AS resulted not only in higher peak flow velocities, but also in fragmented turbulent flow patterns associated with enhanced circumferential strain and an increase in wall thickness of the aortic root. AS mice presented with a mild hypertrophy but unaffected global LV function. Cardiac MR relaxometry revealed reduced values for both T1 and T2 in AS reflecting subtle myocardial tissue remodelling with early alterations in mitochondrial function in response to the enhanced afterload. Concomitantly, incipient impairments of coronary flow reserve and myocardial tissue integrity get apparent accompanied by early troponin release. With this, we identified a premature transition point with still compensated cardiac function but beginning textural changes. This will allow interventional studies to explore early disease pathophysiology and novel therapeutic targets., (© 2022. The Author(s).)