The Biochemical Impact of Extracting an Embedded Adenylate Kinase Domain Using Circular Permutation

Adenylate kinases (AKs) have evolved AMP-binding and lid domains that are encoded as continuous polypeptides embedded at different locations within the discontinuous polypeptide encoding the core domain. A prior study showed that AK homologues of different stabilities consistently retain cellular activity following circular permutation that splits a region with high energetic frustration within the AMP-binding domain into discontinuous fragments. Herein, we show that mesophilic and thermophilic AKs having this topological restructuring retain activity and substrate-binding characteristics of the parental AK. While permutation decreased the activity of both AK homologues at physiological temperatures, the catalytic activity of the thermophilic AK increased upon permutation when assayed >30 °C below the melting temperature of the native AK. The thermostabilities of the permuted AKs were uniformly lower than those of native AKs, and they exhibited multiphasic unfolding transitions, unlike the native AKs, which presented cooperative thermal unfolding. In addition, proteolytic digestion revealed that permutation destabilized each AK in differing manners, and mass spectrometry suggested that the new termini within the AMP-binding domain were responsible for the increased proteolysis sensitivity. These findings illustrate how changes in contact order can be used to tune enzyme activity and alter folding dynamics in multidomain enzymes.

Monkeypox virus-infected individuals mount comparable humoral immune responses as Smallpox-vaccinated individuals

In early 2022, a cluster of monkeypox virus (MPXV) infection (mpox) cases were identified within the UK with no prior travel history to MPXV-endemic regions. Subsequently, case numbers exceeding 80,000 were reported worldwide, primarily affecting gay, bisexual, and other men who have sex with men (GBMSM). Public health agencies worldwide have offered the IMVANEX Smallpox vaccination to these individuals at high-risk to provide protection and limit the spread of MPXV. We have developed a comprehensive array of ELISAs to study poxvirus-induced antibodies, utilising 24 MPXV and 3 Vaccinia virus (VACV) recombinant antigens. Panels of serum samples from individuals with differing Smallpox-vaccine doses and those with prior MPXV infection were tested on these assays, where we observed that one dose of Smallpox vaccination induces a low number of antibodies to a limited number of MPXV antigens but increasing with further vaccination doses. MPXV infection induced similar antibody responses to diverse poxvirus antigens observed in Smallpox-vaccinated individuals. We identify MPXV A27 as a serological marker of MPXV-infection, whilst MPXV M1 (VACV L1) is likely IMVANEX-specific. Here, we demonstrate analogous humoral antigen recognition between both MPXV-infected or Smallpox-vaccinated individuals, with binding to diverse yet core set of poxvirus antigens, providing opportunities for future vaccine (e.g., mRNA) and therapeutic (e.g., mAbs) design.

The Oxidation of Oxygen and Sulfur-Containing Heterocycles by Cytochrome P450 Enzymes

The cytochrome P450 (CYP) superfamily of monooxygenase enzymes play important roles in the metabolism of molecules which contain heterocyclic, aromatic functional groups. Here we study how oxygen- and sulfur-containing heterocyclic groups interact with and are oxidized using the bacterial enzyme CYP199A4. This enzyme oxidized both 4-(thiophen-2-yl)benzoic acid and 4-(thiophen-3-yl)benzoic acid almost exclusively via sulfoxidation. The thiophene oxides produced were activated towards Diels-Alder dimerization after sulfoxidation, forming dimeric metabolites. Despite X-ray crystal structures demonstrating that the aromatic carbon atoms of the thiophene ring were located closer to the heme than the sulfur, sulfoxidation was still favoured with 4-(thiophen-3-yl)benzoic acid. These results highlight a preference of this cytochrome P450 enzyme for sulfoxidation over aromatic hydroxylation. Calculations predict a strong preference for homodimerization of the enantiomers of the thiophene oxides and the formation of a single major product, in broad agreement with the experimental data. 4-(Furan-2-yl)benzoic acid was oxidized to 4-(4'-hydroxybutanoyl)benzoic acid using a whole-cell system. This reaction proceeded via a γ-keto-α,β-unsaturated aldehyde species which could be trapped in vitro using semicarbazide to generate a pyridazine species. The combination of the enzyme structures, the biochemical data and theoretical calculations provides detailed insight into the formation of the metabolites formed from these heterocyclic compounds.

Yeasts Have Evolved Divergent Enzyme Strategies To Deconstruct and Metabolize Xylan

Together with bacteria and filamentous fungi, yeasts actively take part in the global carbon cycle. Over 100 yeast species have been shown to grow on the major plant polysaccharide xylan, which requires an arsenal of carbohydrate active enzymes. However, which enzymatic strategies yeasts use to deconstruct xylan and what specific biological roles they play in its conversion remain unclear. In fact, genome analyses reveal that many xylan-metabolizing yeasts lack expected xylanolytic enzymes. Guided by bioinformatics, we have here selected three xylan-metabolizing ascomycetous yeasts for in-depth characterization of growth behavior and xylanolytic enzymes. The savanna soil yeast Blastobotrys mokoenaii displays superior growth on xylan thanks to an efficient secreted glycoside hydrolase family 11 (GH11) xylanase; solving its crystal structure revealed a high similarity to xylanases from filamentous fungi. The termite gut-associated Scheffersomyces lignosus, in contrast grows more slowly, and its xylanase activity was found to be mainly cell surface-associated. The wood-isolated Wickerhamomyces canadensis, surprisingly, could not utilize xylan as the sole carbon source without the addition of xylooligosaccharides or exogenous xylanases or even co-culturing with B. mokoenaii, suggesting that W. canadensis relies on initial xylan hydrolysis by neighboring cells. Furthermore, our characterization of a novel W. canadensis GH5 subfamily 49 (GH5_49) xylanase represents the first demonstrated activity in this subfamily. Our collective results provide new information on the variable xylanolytic systems evolved by yeasts and their potential roles in natural carbohydrate conversion. IMPORTANCE Microbes that take part in the degradation of the polysaccharide xylan, the major hemicellulose component in plant biomass, are equipped with specialized enzyme machineries to hydrolyze the polymer into monosaccharides for further metabolism. However, despite being found in virtually every habitat, little is known of how yeasts break down and metabolize xylan and what biological role they may play in its turnover in nature. Here, we have explored the enzymatic xylan deconstruction strategies of three underexplored yeasts from diverse environments, Blastobotrys mokoenaii from soil, Scheffersomyces lignosus from insect guts, and Wickerhamomyces canadensis from trees, and we show that each species has a distinct behavior regarding xylan conversion. These findings may be of high relevance for future design and development of microbial cell factories and biorefineries utilizing renewable plant biomass.

Cytochrome P450-catalyzed oxidation of halogen-containing substrates

Cytochrome P450 (CYP) enzymes are heme-thiolate monooxygenases which catalyze the oxidation of aliphatic and aromatic C-H bonds and other reactions. The oxidation of halogens by cytochrome P450 enzymes has also been reported. Here we use CYP199A4, from the bacterium Rhodopseudomonas palustris strain HaA2, with a range of para-substituted benzoic acid ligands, which contain halogens, to assess if this enzyme can oxidize these species or if the presence of these electronegative atoms can alter the outcome of P450-catalyzed reactions. Despite binding to the enzyme, there was no detectable oxidation of any of the 4-halobenzoic acids. CYP199A4 was, however, able to efficiently catalyze the oxidation of both 4-chloromethyl- and 4-bromomethyl-benzoic acid to 4-formylbenzoic acid via hydroxylation of the α‑carbon. The 4-chloromethyl substrate bound in the enzyme active site in a similar manner to 4-ethylbenzoic acid. This places the benzylic α‑carbon hydrogens in an unfavorable position for abstraction indicating a degree of substrate mobility must be possible within the active site. CYP199A4 catalyzed oxidations of 4-(2'-haloethyl)benzoic acids yielding α-hydroxylation and desaturation metabolites. The α-hydroxylation product was the major metabolite. The desaturation pathway is significantly disfavored compared to 4-ethylbenzoic acid. This may be due to the electron-withdrawing halogen atom or a different positioning of the substrate within the active site. The latter was demonstrated by the X-ray crystal structures of CYP199A4 with these substrates. Overall, the presence of a halogen atom positioned close to the heme iron can alter the binding orientation and outcomes of enzyme-catalyzed oxidation.

Investigating the Active Oxidants Involved in Cytochrome P450 Catalyzed Sulfoxidation Reactions

Cytochrome P450 (CYP) heme-thiolate monooxygenases catalyze the hydroxylation of the C-H bonds of organic molecules. This reaction is initiated by a ferryl-oxo heme radical cation (Cpd I). These enzymes can also catalyze sulfoxidation reactions and the ferric-hydroperoxy complex (Cpd 0) and the Fe(III)-H₂ O₂ complex have been proposed as alternative oxidants for this transformation. To investigate this, the oxidation of 4-alkylthiobenzoic acids and 4-methoxybenzoic acid by the CYP199A4 enzyme from Rhodopseudomonas palustris HaA2 was compared using both monooxygenase and peroxygenase pathways. By examining mutants at the mechanistically important, conserved acid alcohol-pair (D251N, T252A and T252E) the relative amounts of the reactive intermediates that would form in these reactions were disturbed. Substrate binding and X-ray crystal structures helped to understand changes in the activity and enabled an attempt to evaluate whether multiple oxidants can participate in these reactions. In peroxygenase reactions the T252E mutant had higher activity towards sulfoxidation than O-demethylation but in the monooxygenase reactions with the WT enzyme the activity of both reactions was similar. The peroxygenase activity of the T252A mutant was greater for sulfoxidation reactions than the WT enzyme, which is the reverse of the activity changes observed for O-demethylation. The monooxygenase activity and coupling efficiency of sulfoxidation and oxidative demethylation were reduced by similar degrees with the T252A mutant. These observations infer that while Cpd I is required for O-dealkylation, another oxidant may contribute to sulfoxidation. Based on the activity of the CYP199A4 mutants it is proposed that this is the Fe(III)-H₂ O₂ complex which would be more abundant in the peroxide-driven reactions.

Antenatal preventative pelvic floor muscle exercise intervention led by midwives to reduce postnatal urinary incontinence (APPEAL): protocol for a feasibility and pilot cluster randomised controlled trial

Background

Antenatal pelvic floor muscle exercises (PFME) in women without prior urinary incontinence (UI) are effective in reducing postnatal UI; however, UK midwives often do not provide advice and information to women on undertaking PFME, with evidence that among women who do receive advice, many do not perform PFME.

Methods

The primary aim of this feasibility and pilot cluster randomised controlled trial is to provide a potential assessment of the feasibility of undertaking a future definitive trial of a midwifery-led antenatal intervention to support women to perform PFME in pregnancy and reduce UI postnatally.

Community midwifery teams in participating NHS sites comprise trial clusters (n = 17). Midwives in teams randomised to the intervention will be trained on how to teach PFME to women and how to support them in undertaking PFME in pregnancy. Women whose community midwifery teams are allocated to control will receive standard antenatal care only.

All pregnant women who give birth over a pre-selected sample month who receive antenatal care from participating community midwifery teams (clusters) will be sent a questionnaire at 10–12 weeks postpartum (around 1400–1500 women). Process evaluation data will include interviews with midwives to assess if the intervention could be implemented as planned. Interviews with women in both trial arms will explore their experiences of support from midwives to perform PFME during pregnancy. Data will be stored securely at the Universities of Birmingham and Exeter.

Results will be disseminated through publications aimed at maternity service users, clinicians, and academics and inform a potential definitive trial of effectiveness. The West Midlands–Edgbaston Research Ethics Committee approved the study protocol.

Discussion

Trial outcomes will determine if criteria to progress to a definitive cluster trial are met. These include women’s questionnaire return rates, prevalence of UI, and other health outcomes as reported by women at 10–12 weeks postpartum. Progress to a definitive trial however is likely to be prevented in the UK context by new perinatal pelvic health service, although this may be possible elsewhere.

Trial registration

10.1186/ISRCTN10833250. Registered 09/03/2020

Exploring the Factors which Result in Cytochrome P450 Catalyzed Desaturation Versus Hydroxylation

The cytochrome P450 family of monooxygenase enzymes have essential biological roles involving the selective oxidation of carbon-hydrogen bonds. They can also catalyze other important metabolic reactions including desaturation to form alkenes. Currently the factors that control the partition between P450 hydroxylation and desaturation pathways are poorly defined. The CYP199A4 enzyme from the bacterium Rhodopseudomonas palustris HaA2 catalyzes the oxidation of 4-ethyl- and 4-isopropyl- benzoic acids with hydroxylation and desaturation occurring in significant quantities. Here we demonstrate that 4-cyclopropylbenzoic acid is regioselectively hydroxylated by CYP199A4 at the benzylic carbon. In contrast, the oxidation of 4- n -propylbenzoic acid by CYP199A4 results in three major metabolites: an alkene from desaturation and two hydroxylation products at the benzylic (Cα) and Cβ carbons in similar quantities. Extending the length of the alkyl substituent resulted in 4- n -butylbenzoic acid being oxidized at the benzylic position (45%) and desaturated (55%). In contrast, 4-isobutylbenzoic generated very little alkene (5%) but was hydroxylated at the benzylic position (54%) and at the tertiary Cβ position (41%). The oxidation of 4- n -propylbenzoic acid by the F298V mutant of CYP199A4 occurred with no hydroxylation at Cβ and a significant increase in metabolites arising from desaturation (73%). The X-ray crystal structures of CYP199A4 with each substrate revealed that they bind in the active site with the alkyl substituent positioned over the heme. However, the longer alkylbenzoic acids were bound in a different conformation as was 4- n -propylbenzoic acid in the F298V mutant. Overall, the changes in metabolite distribution could be ascribed to bond strength differences and the position of the alkyl group relative to the heme.

Quantitative, multiplexed, targeted proteomics for ascertaining variant specific SARS-CoV-2 antibody response

Determining the protection an individual has to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern (VoCs) is crucial for future immune surveillance, vaccine development, and understanding of the changing immune response. We devised an informative assay to current ELISA-based serology using multiplexed, baited, targeted proteomics for direct detection of multiple proteins in the SARS-CoV-2 anti-spike antibody immunocomplex. Serum from individuals collected after infection or first- and second-dose vaccination demonstrates this approach and shows concordance with existing serology and neutralization. Our assays show altered responses of both immunoglobulins and complement to the Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.1) VoCs and a reduced response to Omicron (B1.1.1529). We were able to identify individuals who had prior infection, and observed that C1q is closely associated with IgG1 (r > 0.82) and may better reflect neutralization to VoCs. Analyzing additional immunoproteins beyond immunoglobulin (Ig) G, provides important information about our understanding of the response to infection and vaccination.

Enabling Aromatic Hydroxylation in a Cytochrome P450 Monooxygenase Enzyme through Protein Engineering

The cytochrome P450 (CYP) family of heme monooxygenases catalyse the selective oxidation of C-H bonds under ambient conditions. The CYP199A4 enzyme from Rhodopseudomonas palustris catalyses aliphatic oxidation of 4-cyclohexylbenzoic acid but not the aromatic oxidation of 4-phenylbenzoic acid, due to the distinct mechanisms of aliphatic and aromatic oxidation. The aromatic substrates 4-benzyl-, 4-phenoxy- and 4-benzoyl-benzoic acid and methoxy-substituted phenylbenzoic acids were assessed to see if they could achieve an orientation more amenable to aromatic oxidation. CYP199A4 could catalyse the efficient benzylic oxidation of 4-benzylbenzoic acid. The methoxy-substituted phenylbenzoic acids were oxidatively demethylated with low activity. However, no aromatic oxidation was observed with any of these substrates. Crystal structures of CYP199A4 with 4-(3'-methoxyphenyl)benzoic acid demonstrated that the substrate binding mode was like that of 4-phenylbenzoic acid. 4-Phenoxy- and 4-benzoyl-benzoic acid bound with the ether or ketone oxygen atom hydrogen-bonded to the heme aqua ligand. We also investigated whether the substitution of phenylalanine residues in the active site could permit aromatic hydroxylation. Mutagenesis of the F298 residue to a valine did not significantly alter the substrate binding position or enable the aromatic oxidation of 4-phenylbenzoic acid; however the F182L mutant was able to catalyse 4-phenylbenzoic acid oxidation generating 2'-hydroxy-, 3'-hydroxy- and 4'-hydroxy metabolites in a 83 : 9 : 8 ratio, respectively. Molecular dynamics simulations, in which the distance and angle of attack were considered, demonstrated that in the F182L variant, in contrast to the wild-type enzyme, the phenyl ring of 4-phenylbenzoic acid attained a productive geometry for aromatic oxidation to occur.

Immune boosting by B.1.1.529 Omicron) depends on previous SARS-CoV-2 exposure

The Omicron, or Pango lineage B.1.1.529, variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) carries multiple spike mutations with high transmissibility and partial neutralizing antibody (nAb) escape. Vaccinated individuals show protection against severe disease, often attributed to primed cellular immunity. We investigated T and B cell immunity against B.1.1.529 in triple BioNTech BNT162b2 messenger RNA-vaccinated health care workers (HCWs) with different SARS-CoV-2 infection histories. B and T cell immunity against previous variants of concern was enhanced in triple-vaccinated individuals, but the magnitude of T and B cell responses against B.1.1.529 spike protein was reduced. Immune imprinting by infection with the earlier B.1.1.7 (Alpha) variant resulted in less durable binding antibody against B.1.1.529. Previously infection-naïve HCWs who became infected during the B.1.1.529 wave showed enhanced immunity against earlier variants but reduced nAb potency and T cell responses against B.1.1.529 itself. Previous Wuhan Hu-1 infection abrogated T cell recognition and any enhanced cross-reactive neutralizing immunity on infection with B.1.1.529.

Development of a cost-effective ovine antibody-based therapy against SARS-CoV-2 infection and contribution of antibodies specific to the spike subunit proteins

Antibodies against SARS-CoV-2 are important to generate protective immunity, with convalescent plasma one of the first therapies approved. An alternative source of polyclonal antibodies suitable for upscaling would be more amendable to regulatory approval and widespread use. In this study, sheep were immunised with SARS-CoV-2 whole spike protein or one of the subunit proteins: S1 and S2. Once substantial antibody titres were generated, plasma was collected and samples pooled for each antigen. Non-specific antibodies were removed via affinity-purification to yield candidate products for testing in a hamster model of SARS-CoV-2 infection. Affinity-purified polyclonal antibodies to whole spike, S1 and S2 proteins were evaluated for in vitro for neutralising activity against SARS-CoV-2 Wuhan-like virus (Australia/VIC01/2020) and a recent variant of concern, B.1.1.529 BA.1 (Omicron), antibody-binding, complement fixation and phagocytosis assays were also performed. All antibody preparations demonstrated an effect against SARS-CoV-2 disease in the hamster model of challenge, with those raised against the S2 subunit providing the most promise. A rapid, cost-effective therapy for COVID-19 was developed which provides a source of highly active immunoglobulin specific to SARS-CoV-2 with multi-functional activity.

Screening of wild deer populations for exposure to SARS-CoV-2 in the United Kingdom, 2020-2021

Following findings in Northern America of SARS‐CoV‐2 infections in white‐tailed deer, there is concern of similar infections in European deer and their potential as reservoirs of SARS‐CoV‐2 including opportunities for the emergence of new variants. UK deer sera were collected in 2020–2021 from 6 species and a hybrid with 1748 tested using anti‐spike and anti‐nucleocapsid serology assays. No samples were positive on both assays nor by surrogate neutralization testing. There is no evidence that spill‐over infections of SARS‐CoV‐2 occurred from the human population to UK deer or that SARS‐CoV‐2 has been circulating in UK deer (over the study period). Although it cannot be ruled out, study results indicate that spill‐over infections followed by circulation of SARS‐CoV‐2 to the most common European deer species is small.

Structural diversity and substrate preferences of three tannase enzymes encoded by the anaerobic bacterium Clostridium butyricum

Tannins are secondary metabolites that are enriched in the bark, roots, and knots in trees and are known to hinder microbial attack. The biological degradation of water-soluble gallotannins, such as tannic acid, is initiated by tannase enzymes (EC 3.1.1.20), which are esterases able to liberate gallic acid from aromatic-sugar complexes. However, only few tannases have previously been studied in detail. Here, for the first time, we biochemically and structurally characterize three tannases from a single organism, the anaerobic bacterium Clostridium butyricum, which inhabits both soil and gut environments. The enzymes were named CbTan1-3, and we show that each one exhibits a unique substrate preference on a range of galloyl ester model substrates; CbTan1 and 3 demonstrated preference toward galloyl esters linked to glucose, while CbTan2 was more promiscuous. All enzymes were also active on oak bark extractives. Furthermore, we solved the crystal structure of CbTan2 and produced homology models for CbTan1 and 3. In each structure, the catalytic triad and gallate-binding regions in the core domain were found in very similar positions in the active site compared with other bacterial tannases, suggesting a similar mechanism of action among these enzymes, though large inserts in each enzyme showcase overall structural diversity. In conclusion, the varied structural features and substrate specificities of the C. butyricum tannases indicate that they have different biological roles and could further be used in development of new valorization strategies for renewable plant biomass.

To Be, or Not to Be, an Inhibitor: A Comparison of Azole Interactions with and Oxidation by a Cytochrome P450 Enzyme

The cytochrome P450 (CYP) superfamily of heme monooxygenases is involved in a range of important chemical biotransformations across nature. Azole-containing molecules have been developed as drugs that bind to the heme center of these enzymes, inhibiting their function. The optical spectrum of CYP enzymes after the addition of these inhibitors is used to assess how the molecules bind. Here we use the bacterial CYP199A4 enzyme, from Rhodopseudomonas palustris HaA2, to compare how imidazolyl and triazolyl inhibitors bind to ferric and ferrous heme. 4-(Imidazol-1-yl)benzoic acid induced a red shift in the Soret wavelength (424 nm) in the ferric enzyme along with an increase and a decrease in the intensities of the δ and α bands, respectively. 4-(1H-1,2,4-Triazol-1-yl)benzoic acid binds to CYP199A4 with a 10-fold lower affinity and induces a smaller red shift in the Soret band. The crystal structures of CYP199A4 with these two inhibitors confirmed that these differences in the optical spectra were due to coordination of the imidazolyl ligand to the ferric Fe, but the triazolyl inhibitor interacts with, rather than displaces, the ferric aqua ligand. Additional water molecules were present in the active site of 4-(1H-1,2,4-triazol-1-yl)benzoic acid-bound CYP199A4. The space required to accommodate these additional water molecules in the active site necessitates changes in the position of the hydrophobic phenylalanine 298 residue. Upon reduction of the heme, the imidazole-based inhibitor Fe-N ligation was not retained. A 5-coordinate heme was also the predominant species in 4-(1H-1,2,4-triazol-1-yl)benzoic acid-bound ferrous CYP199A4, but there was an obvious shoulder at 447 nm indicative of some degree of Fe-N coordination. Rather than inhibit CYP199A4, 4-(imidazol-1-yl)benzoic acid was a substrate and was oxidized to generate a metabolite derived from ring opening of the imidazolyl ring: 4-[[2-(formylamino)acetyl]amino]benzoic acid.

The stereoselective oxidation of para-substituted benzenes by a cytochrome P450 biocatalyst

The serine 244 to aspartate (S244D) variant of the cytochrome P450 enzyme CYP199A4 was used to expand its substrate range beyond benzoic acids. Substrates, in which the carboxylate group of the benzoic acid moiety is replaced, were oxidised with high activity by the S244D mutant (product formation rates > 60 nmol.(nmol-CYP) -1 .min -1 ) and with total turnover numbers of up to 20,000. Ethyl α-hydroxylation was more rapid than methyl oxidation, styrene epoxidation and S -oxidation. The S244D mutant catalysed the ethyl hydroxylation, epoxidation and sulfoxidation reactions with an excess of one stereoisomer (in some instances up to >98%). The crystal structure of 4-methoxybenzoic acid-bound CYP199A4 S244D showed that the active site architecture and the substrate orientation were similar to that of the WT enzyme. Overall, this work demonstrates that CYP199A4 can catalyse the stereospecific hydroxylation, epoxidation or sulfoxidation of substituted benzene substrates under mild conditions resulting in more sustainable transformations using this heme monooxygenase enzyme.

Financial Incentives for Preventing Postpartum return to Smoking (FIPPS): study protocol for a three-arm randomised controlled trial

Background

Financial incentives are an effective way of helping women to stop smoking during pregnancy. Unfortunately, most women who stop smoking at this time return to smoking within 12 months of the infant’s birth. There is no evidence for interventions that are effective at preventing postpartum smoking relapse. Financial incentives provided after the birth may help women to sustain cessation. This randomised controlled trial will assess the effectiveness and cost-effectiveness of financial incentives to help women who are abstinent from smoking at end-of-pregnancy to avoid return to smoking up to 12 months postpartum.

Methods

This is a UK-based, multi-centre, three-arm, superiority, parallel group, individually randomised controlled trial, with 1:1:1 allocation. It will compare the effectiveness of two financial incentive interventions with each other (one intervention for up to 3 months postpartum offering up to £120 of incentives (£60 for the participant and £60 for a significant other support); the other for up to 12 months postpartum with up to £300 of incentives (£240 for the participant and £60 for a significant other support) and with a no incentives/usual care control group. Eligible women will be between 34 weeks gestation and 2 weeks postpartum, abstinent from smoking for at least 4 weeks, have an expired carbon monoxide (CO) reading < 4 parts per million (ppm), aged at least 16 years, intend remaining abstinent from smoking after the birth and able to speak and read English.

The primary outcome is self-reported, lapse-free, smoking abstinence from the last quit attempt in pregnancy until 12 months postpartum, biochemically validated by expired CO and/or salivary cotinine or anabasine. Outcomes will be analysed by intention-to-treat and regression models used to compare the proportion of abstinent women between the two intervention groups and between each intervention group and the control group. An economic evaluation will assess the cost-effectiveness of offering incentives and a qualitative process evaluation will examine barriers and facilitators to trial retention, effectiveness and implementation.

Discussion

This pragmatic randomised controlled trial will test whether offering financial incentives is effective and cost-effective for helping women to avoid smoking relapse during the 12 months after the birth of their baby.

Trial registration

International Standard Randomised Controlled Trial Number 55218215. Registered retrospectively on 5th June 2019

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05480-6.

Pregnant women's use of e-cigarettes in the UK: a cross-sectional survey

OBJECTIVE

To estimate prevalence of vaping in pregnancy. Compare characteristics and attitudes between exclusive smokers and vapers, and between exclusive vapers and dual users (smoke and vape).

DESIGN

Cross-sectional survey.

SETTING

Hospitals across England and Scotland.

POPULATION

Pregnant women attending antenatal clinics in 2017.

METHODS

Women at 8-24 weeks' gestation completed screening questions about their smoking and vaping. Current or recent ex-smokers and/or vapers completed a full detailed survey about vaping and smoking.

MAIN OUTCOME MEASURES

The prevalence of vaping, characteristics and attitudes of women who vape and/or smoke.

RESULTS

Of 3360 pregnant women who completed screening questions, 515 (15.3%, 95% CI 14.1-16.6) were exclusive smokers, 44 (1.3%, 95% CI 1.0-1.8) exclusive vapers and 118 (3.5%, 95% CI 2.9-4.2) dual users. In total, 867 (25.8%) women completed the full survey; compared with smokers (n = 434), vapers (n = 140) were more likely to hold higher educational qualifications (odds ratio [OR) 1.51, 95% CI 1.01-2.25). Compared with exclusive vapers (n = 33), dual users (n = 107) were younger (OR 0.91 95% CI 0.85-0.98) and less likely to hold high qualifications (OR 0.43, 95% CI 0.20-0.96). Compared with smokers, dual users were more likely to be planning to quit smoking (OR 2.27, 95% CI 1.24-4.18). Compared with smokers, vapers were more likely to think vaping was safer than smoking (78.6% versus 36.4%).

CONCLUSIONS

One in 20 pregnant women report vaping, and most also smoke. Dual users are more motivated towards stopping smoking than smokers. Where women have tried but cannot stop smoking, clinicians could encourage them to consider vaping for smoking cessation.

TWEETABLE EXTRACT

One in 20 women report vaping during pregnancy but of those that do vape, most also smoke, despite having intentions to quit.

Structural insights into the role of the acid-alcohol pair of residues required for dioxygen activation in cytochrome P450 enzymes

The cytochrome P450 heme monooxygenases commonly use an acid-alcohol pair of residues, within the I-helix, to activate iron-bound dioxygen. This work aims to clarify conflicting reports on the importance of the alcohol functionality in this process. Mutants of the P450, CYP199A4 (CYP199A4_D251N and CYP199A4_T252A), were prepared, characterised and their crystal structures were solved. The acid residue of CYP199A4 is not part of a salt bridge network, a key feature of paradigmatic model system P450cam. Instead, there is a direct proton delivery network, via a chain of water molecules, extending to the surface. Nevertheless, CYP199A4_D251N dramatically reduced the activity of the enzyme consistent with a role in proton delivery. CYP199A4_T252A decreased the coupling efficiency of the enzyme with a concomitant increase in the hydrogen peroxide uncoupling pathway. However, the effect of this mutation was much less pronounced than reported with P450cam. Its crystal structures revealed fewer changes at the I-helix, compared to the P450cam system. The structural changes observed within the I-helix of P450cam during oxygen activation do not seem to be required in this P450. These differences are due to the presence of a second threonine residue at position 253, which is absent in P450cam. This threonine forms part of the hydrogen bonding network, resulting in subtle structural changes and is also present across the majority of the P450 superfamily. Overall, the results suggest that while the acid-alcohol pair is important for dioxygen activation this process and the method of proton delivery can differ across P450s.Graphic abstract.

Biophysical Techniques for Distinguishing Ligand Binding Modes in Cytochrome P450 Monooxygenases

The cytochrome P450 superfamily of heme monooxygenases catalyzes important chemical reactions across nature. The changes in the optical spectra of these enzymes, induced by the addition of substrates or inhibitors, are critical for assessing how these molecules bind to the P450, enhancing or inhibiting the catalytic cycle. Here we use the bacterial CYP199A4 enzyme (Uniprot entry Q2IUO2), from Rhodopseudomonas palustris HaA2, and a range of substituted benzoic acids to investigate different binding modes. 4-Methoxybenzoic acid elicits an archetypal type I spectral response due to a ≥95% switch from the low- to high-spin state with concomitant dissociation of the sixth aqua ligand. 4-(Pyridin-3-yl)- and 4-(pyridin-2-yl)benzoic acid induced different type II ultraviolet-visible (UV-vis) spectral responses in CYP199A4. The former induced a greater red shift in the Soret wavelength (424 nm vs 422 nm) along with a larger overall absorbance change and other differences in the α-, β-, and δ-bands. There were also variations in the ferrous UV-vis spectra of these two substrate-bound forms with a spectrum indicative of Fe-N bond formation with 4-(pyridin-3-yl)benzoic acid. The crystal structures of CYP199A4, with the pyridinyl compounds bound, revealed that while the nitrogen of 4-(pyridin-3-yl)benzoic acid is coordinated to the heme, with 4-(pyridin-2-yl)benzoic acid an aqua ligand remains. Continuous wave and pulse electron paramagnetic resonance data in frozen solution revealed that the substrates are bound in the active site in a form consistent with the crystal structures. The redox potential of each CYP199A4-substrate combination was measured, allowing correlation among binding modes, spectroscopic properties, and the observed biochemical activity.

Investigation of the requirements for efficient and selective cytochrome P450 monooxygenase catalysis across different reactions

The cytochrome P450 metalloenzyme (CYP) CYP199A4 from Rhodopseudomonas palustris HaA2 catalyzes the highly efficient oxidation of para-substituted benzoic acids. Here we determined crystal structures of CYP199A4, and the binding and turnover parameters, with different meta-substituted benzoic acids in order to establish which criteria are important for efficient catalysis. When compared to the para isomers, the meta-substituted benzoic acids were less efficiently oxidized. For example, 3-formylbenzoic acid was oxidized with lower activity than the equivalent para isomer and 3-methoxybenzoic acid did not undergo O-demethylation by CYP199A4. The structural data highlighted that the meta-substituted benzoic acids bound in the enzyme active site in a modified position with incomplete loss of the distal water ligand of the heme moiety. However, for both sets of isomers the meta- or para-substituent pointed towards, and was in close proximity, to the heme iron. The absence of oxidation activity with 3-methoxybenzoic acid was assigned to the observation that the CH bonds of this molecule point away from the heme iron. In contrast, in the para isomer they are in an ideal location for abstraction. These findings were confirmed by using the bulkier 3-ethoxybenzoic acid as a substrate which removed the water ligand and reoriented the meta-substituent so that the methylene hydrogens pointed towards the heme, enabling more efficient oxidation. Overall we show relatively small changes in substrate structure and position in the active site can have a dramatic effect on the activity.

Factors associated with the effectiveness and reach of NHS stop smoking services for pregnant women in England

BACKGROUND

The UK National Health Service provides Stop Smoking Services for pregnant women (SSSP) but there is a lack of evidence concerning how these are best organised. This study investigates influences on services' effectiveness and also on their propensity to engage pregnant smokers with support in stopping smoking.

METHODS

Survey data collected from 121/141 (86%) of SSSP were augmented with data from Hospital Episode Statistics and the 2011 UK National Census. 'Reach' or propensity to engage smokers with support was defined as the percentage of pregnant smokers setting a quit date with SSSP support, and 'Effectiveness' as the percentage of women who set a quit date who also reported abstinence at four weeks later. A bivariate (i.e. two outcome variable) response Markov Chain Monte Carlo model was used to identify service-level factors associated with the Reach and Effectiveness of SSSP.

RESULTS

Beta coefficients represent a percentage change in Reach and Effectiveness by the covariate. Providing the majority of one-to-one contacts in a clinic rather than at home increased both Reach (%) (β: 6.97, 95% CI: 3.34, 10.60) and Effectiveness (%) (β: 7.37, 95% CI: 3.03, 11.70). Reach of SSSP was also increased when the population served was more deprived (β for increase in Reach with a one unit increase in IMD score: 0.55, 95% CI: 0.25, 0.85), had a lower proportion of people with dependent children (β: -2.52, 95% CI: -3.82, -1.22), and a lower proportion of people in managerial or professional occupations (β: -0.31, 95% CI: -0.59, -0.03). The Effectiveness of SSSP was decreased in those areas that had a greater percentage of people >16 years with no educational qualifications (β: -0.51, 95% CI: -0.95, -0.07).

CONCLUSIONS

To engage pregnant smokers and to encourage them to quit, it may be more efficient for SSSP support to be focussed around clinics, rather than women's homes. Reach of SSSP is inversely associated with disadvantage and efforts should be made to contact these women as they are less likely to achieve abstinence in the short and longer term.

Abstract P5-10-10: Predictors of breast density among Black and Hispanic women presenting for mammographic screening

Background: Increased breast density has been associated with elevated breast cancer risk and complicating mammographic interpretation. Although previous studies have investigated population variations in breast density, Black and Hispanic women are often underrepresented in these analyses. Moreover, it is unclear how breast density differs between these ethnicities. We report on the mammographic density distribution of Black and Hispanic women having breast cancer screening at the Capital Breast Care Center (CBCC) and analyze factors associated with high breast density.

Methods: Retrospective data from electronic medical records at a population-based mammography screening center were abstracted. From 2010 to 2014, data from women undergoing their first breast cancer screening were reviewed. Patient demographics including race, age at screening, education and menopausal status were abstracted in addition to body mass index (BMI) and Breast Imaging-Reporting and Data System (BI-RADS) density category:1- “fatty”, 2- “scattered fibroglandular densities”, 3- “heterogeneously dense” and 4- “extremely dense”. Logistic regression was used to investigate factors associated with breast density.

Results: Density categorization was recorded for 1747 women over the five-year period, with 855 (49%) Black and 892 (51%) Hispanic. Patient characteristics associated with high density (categories 3 and 4) were younger age, Hispanic ethnicity, nulliparity, premenopausal status, and BMI &lt; 30 kg/m2. On multivariate logistic regression, Hispanic ethnicity, premenopausal status, and BMI &lt; 30 kg/m2 were predictive of high mammographic density.

Conclusion: In a sample of women presenting for mammographic screening at CBCC, Hispanic women were more likely to have higher breast density compared to Black women. After controlling for ethnicity, postmenopausal and obese women were less likely to have dense breasts. Additional investigation is needed to further study the impact of obesity on breast density in underserved minority women.

Citation Format: Oppong BA, Dash C, Li Y, Makambi K, Coleman T, Adams-Campbell L. Predictors of breast density among Black and Hispanic women presenting for mammographic screening [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-10-10.

CYP199A4 catalyses the efficient demethylation and demethenylation of para-substituted benzoic acid derivatives

CYP199A4, a cytochrome P450 enzyme from Rhodopseudomonas palustris HaA2, is able to efficiently demethylate a range of benzoic acids at the para-position. It can also catalyse demethenylation reactions.

Pedestrian traffic deaths among residents, visitors, and homeless persons--Clark County, Nevada, 2008-2011

Motor vehicle collisions and crashes are a leading cause of death among Nevada residents aged 5-34 years, representing 14% of all injury deaths in that age group in 2010. During 2008-2011, a total of 173 pedestrian deaths from motor vehicle collisions occurred in Nevada, accounting for 16% of motor vehicle deaths in the state. Approximately 75% (2 million persons) of Nevada residents live in Clark County, which includes the city of Las Vegas. To analyze pedestrian traffic deaths in Clark County among residents, visitors, and homeless persons, the Southern Nevada Health District used coroner's office data and death certificate data for the period 2008-2011. The results indicated that the average annual pedestrian traffic death rates from motor vehicle collisions during this period were 1.4 per 100,000 population for residents, 1.1 for visitors, and 30.7 for homeless persons. Among the three groups, time of day, location of motor vehicle collisions, and pedestrian blood alcohol concentration (BAC) differed. Effective interventions to increase roadway safety, such as lowering speed limits in areas with greater pedestrian traffic, targeting interventions during hours when alcohol-impaired walking is more likely, and modifying roadway designs to increase protection of pedestrians, might decrease pedestrian deaths among all three groups.

Metastatic breast cancer detection and therapy monitoring using folate-targeting flow cytometry

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Background: Circulating tumor cell (CTC) has emerged as a valuable surrogate tumor marker for cancer diagnosis, prognosis, therapy personalization, and drug discovery. To identify CTCs, EpCAM and/or cytokeratin have been commonly used; however, their expression may diminish for subgroups of breast cancers or during epithelial-mesenchymal transition. A unique approach by targeting folate receptor (FR) on CTCs overcomes the limitation. Cancer cells overexpress FR with high affinity (KD=0.1 nM) to internalize high levels of folate for rapid growth. FR is also found upregulated in most cancers, while at very low levels in normal tissues.

Methods: A flow cytometry based in-vitro CTC assay kit (OncoIVDx) was developed by IV Diagnostics Inc to specifically enumerate CTCs which overexpress FRs. 20 mL of 9 metastatic breast cancer (MBC) patients' peripheral blood was collected using CellSave tube before and after the treatment in midst of therapy. CTCs were tagged by fluorescently labeled folate conjugate, while leukocytes were counterstained by anti-CD45. To absolutely count the rare CTCs, a fluorescent bead was added serving internal control.

Results: Table.

Conclusions: No obvious shift in dot plots was found for patients' leucocytes compared to those in normal sample. Tumor size, histologic grade, nodal involvement and lymphovascular invasion (LVI) did not display a significant association with CTC presence, although more positive nodes with identified LVI might indicate an unfavorable increase in CTC counts. CTC presence was found associated with serum marker CA27.29. A score of 30 and less correlated with CTC response to the treatment. Chemotherapy alone or in combination with hormone therapy did not correlate with the change in CTC counts after treatment, except for hormone therapy alone. Unfavorable progression of cancers could be predicated for the patients with approximately 25 and more CTCs. We would like to thank NIH/NCI for SBIR phase I grant (1R43CA13789301A1).

[Table: see text]

Intestinal ciprofloxacin efflux: the role of breast cancer resistance protein (ABCG2)

Intestinal secretory movement of the fluoroquinolone antibiotic, ciprofloxacin, may limit its oral bioavailability. Active ATP-binding cassette (ABC) transporters such as breast cancer resistance protein (BCRP) have been implicated in ciprofloxacin transport. The aim of this study was to test the hypothesis that BCRP alone mediates intestinal ciprofloxacin secretion. The involvement of ABC transport proteins in ciprofloxacin secretory flux was investigated with the combined use of transfected cell lines [bcrp1/BCRP-Madin-Darby canine kidney II (MDCKII) and multidrug resistance-related protein 4 (MRP4)-human embryonic kidney (HEK) 293] and human intestinal Caco-2 cells, combined with pharmacological inhibition using 3-(6-isobutyl-9-methoxy-1,4-dioxo-1,2,3,4,6, 7,12,12a-octahydropyrazino[1',2':1,6]pyrido[3,4-b]indol-3-yl)-propionic acid tert-butyl ester (Ko143), cyclosporine, 3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl] propionic acid (MK571), and verapamil as ABC-selective inhibitors. In addition, the regional variation in secretory capacity was investigated using male Han Wistar rat intestine mounted in Ussing chambers, and the first indicative measurements of ciprofloxacin transport by ex vivo human jejunum were made. Active, Ko143-sensitive ciprofloxacin secretion was observed in bcrp1-MDCKII cell layers, but in low-passage (BCRP-expressing) Caco-2 cell layers only a 54% fraction was Ko143-sensitive. Ciprofloxacin accumulation was lower in MRP4-HEK293 cells than in the parent line, indicating that ciprofloxacin is also a substrate for this transporter. Ciprofloxacin secretion by Caco-2 cell layers was not inhibited by MK571. Secretory flux showed marked regional variability in the rat intestine, increasing from the duodenum to peak in the ileum. Ciprofloxacin secretion was present in human jejunum and was reduced by Ko143 but showed marked interindividual variability. Ciprofloxacin is a substrate for human and rodent BCRP. An additional pathway for ciprofloxacin secretion exists in Caco-2 cells, which is unlikely to be MRP(4)-mediated. BCRP is likely to be the dominant transport mechanism for ciprofloxacin efflux in both rat and human jejunum.

Carcinomatous meningitis: the natural history of successfully treated metastatic bladder cancer

Carcinomatous meningitis due to bladder cancer is a rare entity reported only in case reports. Optimal therapy is thus poorly defined with earlier cases reporting an unsuccessful outcome. Here we report a case of late carcinomatous meningitis secondary to transitional cell carcinoma (TCC) of the bladder occurring in a patient in complete remission. He was successfully treated with intrathecal methotrexate and whole brain irradiation and experienced prolonged survival after treatment. With modern chemotherapy increasing complete remissions and survival rates in patients with TCC, more and more patients are being reported with carcinomatous meningitis. We raise the question of whether central nervous system prophylaxis should be considered in patients with TCC achieving a complete remission to chemotherapy in the metastatic setting.

Regulation of methionine synthesis in Escherichia coli: Effect of metJ gene product and S-adenosylmethionine on the expression of the metF gene

The regulation of the expression of the Escherichia coli metF gene, which codes for 5,10-methylenetet-rahydrofolate reductase (EC 1.1.99.15), has been investigated by using a simplified DNA-directed in vitro system that measures the formation of the first dipeptide (fMet-Ser) of the gene product. The synthesis of fMet-Ser directed by a plasmid containing the metF gene is specifically inhibited by metJ protein (repressor protein). S-Adenosylmethionine enhances the inhibition by the metJ protein of metF gene expression. The inhibition by the metJ protein is at the level of transcription and the results suggest that S-adenosylmethionine is functioning as an allosteric effector.

Environmental tobacco smoke and fetal health: systematic review and meta-analysis

OBJECTIVE

To determine the effects of environmental tobacco smoke (ETS) exposure on birth outcomes.

DESIGN

A systematic review and meta-analysis was performed in accordance with MOOSE guidelines. MEDLINE, EMBASE, CINAHL and LILACS (up to October 2007), were searched and also reviews and reference lists from publications, with no language restrictions. Pooled mean differences and odds ratios (ORs) with 95% confidence intervals were estimated using data extracted from papers, based on random effect models.

SETTING

Comparative epidemiological studies.

PATIENTS

Pregnant women or women who have given birth.

EXPOSURES

Maternal exposure to ETS during pregnancy.

MAIN OUTCOME MEASURES

Mean birth weight and proportion of premature infants.

RESULTS

58 studies were included; 53 used cohort designs, 23 ascertaining ETS exposure prospectively and 30 retrospectively; 5 used case-control designs. In prospective studies, ETS exposure was associated with a 33 g (95% CI 16 to 51) reduction in mean birth weight, and in retrospective studies a 40 g (95% CI 26 to 54) reduction. ETS exposure was also associated with an increased risk of low birth weight (birth weight <2500 g; prospective studies: OR 1.32, 95% CI 1.07 to 1.63; retrospective studies: OR 1.22, 95% CI 1.08 to 1.37). The risk of small for gestational age (<10th centile) birth was significantly associated with ETS exposure only in retrospective studies (OR 1.21, 95% CI 1.06 to 1.37). There was no effect of ETS exposure on gestational age.

CONCLUSIONS

Exposure of non-smoking pregnant women to ETS reduces mean birth weight by 33 g or more, and increases the risk of birth weight below 2500 g by 22%, but has no clear effect on gestation or the risk of being small for gestational age.

Induction of P-glycoprotein expression and function in human intestinal epithelial cells (T84)

Intestinal induction of Pgp is known to limit the oral availability of certain drug compounds and give rise to detrimental drug-drug interactions. We have investigated the induction of P-glycoprotein (Pgp; MDR1) activity in a human intestinal epithelial cell line (T84) following pre-exposure to a panel of drug compounds, reported to be Pgp substrates, inhibitors or inducers. Human MDR1-transfected MDCKII epithelial monolayers were used to assess Pgp substrate interactions and inhibition of digoxin secretion by the selected drug compounds. The T84 cell line was used to assess induction of Pgp-mediated digoxin secretion following pre-exposure to the same compounds. Changes in gene expression (MDR1, MRP2, PXR and CAR) were determined by quantitative RT-PCR. Net transepithelial digoxin secretion was increased (1.3 fold, n=6, P<0.05) following pre-exposure to the PXR activator hyperforin (100nM, 72h), as was MDR1 mRNA expression (3.0 fold, n=4, P<0.05). A number of Pgp substrates (quinidine, amprenavir, irinotecan, topotecan, atorvastatin and erythromycin) induced net digoxin secretion, as did the non-Pgp substrate artemisinin. Various non-Pgp substrates demonstrated inhibition of digoxin secretion (verapamil, mifepristone, clotrimazole, mevastatin, diltiazem and isradipine) but did not induce Pgp-mediated digoxin secretion. Of the compounds that increased Pgp secretion, quinidine, topotecan, atorvastatin and amprenavir pre-exposure also elevated MDR1 mRNA levels, whereas erythromycin, irinotecan and artemisinin displayed no change in transcript levels. This indicates possible post-translational regulation of digoxin secretion. Finally, a strong correlation between drug modulation of MRP2 and PXR mRNA expression levels was evident.