Structural basis of tankyrase activation by polymerization.

The poly-ADP-ribosyltransferase tankyrase (TNKS, TNKS2) controls a wide range of disease-relevant cellular processes, including WNT-ß-catenin signalling, telomere length maintenance, Hippo signalling, DNA damage repair and glucose homeostasis1,2. This has incentivized the development of tankyrase inhibitors. Notwithstanding, our knowledge of the mechanisms that control tankyrase activity has remained limited. Both catalytic and non-catalytic functions of tankyrase depend on its filamentous polymerization3-5. Here we report the cryo-electron microscopy reconstruction of a filament formed by a minimal active unit of tankyrase, comprising the polymerizing sterile alpha motif (SAM) domain and its adjacent catalytic domain. The SAM domain forms a novel antiparallel double helix, positioning the protruding catalytic domains for recurring head-to-head and tail-to-tail interactions. The head interactions are highly conserved among tankyrases and induce an allosteric switch in the active site within the catalytic domain to promote catalysis. Although the tail interactions have a limited effect on catalysis, they are essential to tankyrase function in WNT-ß-catenin signalling. This work reveals a novel SAM domain polymerization mode, illustrates how supramolecular assembly controls catalytic and non-catalytic functions, provides important structural insights into the regulation of a non-DNA-dependent poly-ADP-ribosyltransferase and will guide future efforts to modulate tankyrase and decipher its contribution to disease mechanisms.

Human Condensin I and II Drive Extensive ATP-Dependent Compaction of Nucleosome-Bound DNA.

Structural maintenance of chromosomes (SMC) complexes are essential for genome organization from bacteria to humans, but their mechanisms of action remain poorly understood. Here, we characterize human SMC complexes condensin I and II and unveil the architecture of the human condensin II complex, revealing two putative DNA-entrapment sites. Using single-molecule imaging, we demonstrate that both condensin I and II exhibit ATP-dependent motor activity and promote extensive and reversible compaction of double-stranded DNA. Nucleosomes are incorporated into DNA loops during compaction without being displaced from the DNA, indicating that condensin complexes can readily act upon nucleosome-bound DNA molecules. These observations shed light on critical processes involved in genome organization in human cells.

Investigating the synergistic effects of hormone replacement therapy, apolipoprotein E and age on brain health in the UK Biobank.

Global prevalence of Alzheimer's Disease has a strong sex bias, with women representing approximately two-thirds of the patients. Yet, the role of sex-specific risk factors during midlife, including hormone replacement therapy (HRT) and their interaction with other major risk factors for Alzheimer's Disease, such as apolipoprotein E (APOE)-e4 genotype and age, on brain health remains unclear. We investigated the relationship between HRT (i.e., use, age of initiation and duration of use) and brain health (i.e., cognition and regional brain volumes). We then consider the multiplicative effects of HRT and APOE status (i.e., e2/e2, e2/e3, e3/e3, e3/e4 and e4/e4) via a two-way interaction and subsequently age of participants via a three-way interaction. Women from the UK Biobank with no self-reported neurological conditions were included (N = 207,595 women, mean age = 56.25 years, standard deviation = 8.01 years). Generalised linear regression models were computed to quantify the cross-sectional association between HRT and brain health, while controlling for APOE status, age, time since attending centre for completing brain health measure, surgical menopause status, smoking history, body mass index, education, physical activity, alcohol use, ethnicity, socioeconomic status, vascular/heart problems and diabetes diagnosed by doctor. Analyses of structural brain regions further controlled for scanner site. All brain volumes were normalised for head size. Two-way interactions between HRT and APOE status were modelled, in addition to three-way interactions including age. Results showed that women with the e4/e4 genotype who have used HRT had 1.82% lower hippocampal, 2.4% lower parahippocampal and 1.24% lower thalamus volumes than those with the e3/e3 genotype who had never used HRT. However, this interaction was not detected for measures of cognition. No clinically meaningful three-way interaction between APOE, HRT and age was detected when interpreted relative to the scales of the cognitive measures used and normative models of ageing for brain volumes in this sample. Differences in hippocampal volume between women with the e4/e4 genotype who have used HRT and those with the e3/e3 genotype who had never used HRT are equivalent to approximately 1-2 years of hippocampal atrophy observed in typical health ageing trajectories in midlife (i.e., 0.98%-1.41% per year). Effect sizes were consistent within APOE e4/e4 group post hoc sensitivity analyses, suggesting observed effects were not solely driven by APOE status and may, in part, be attributed to HRT use. Although, the design of this study means we cannot exclude the possibility that women who have used HRT may have a predisposition for poorer brain health.

Concerted loading of Mcm2-7 double hexamers around DNA during DNA replication origin licensing.

The licensing of eukaryotic DNA replication origins, which ensures once-per-cell-cycle replication, involves the loading of six related minichromosome maintenance proteins (Mcm2-7) into prereplicative complexes (pre-RCs). Mcm2-7 forms the core of the replicative DNA helicase, which is inactive in the pre-RC. The loading of Mcm2-7 onto DNA requires the origin recognition complex (ORC), Cdc6, and Cdt1, and depends on ATP. We have reconstituted Mcm2-7 loading with purified budding yeast proteins. Using biochemical approaches and electron microscopy, we show that single heptamers of Cdt1*Mcm2-7 are loaded cooperatively and result in association of stable, head-to-head Mcm2-7 double hexamers connected via their N-terminal rings. DNA runs through a central channel in the double hexamer, and, once loaded, Mcm2-7 can slide passively along double-stranded DNA. Our work has significant implications for understanding how eukaryotic DNA replication origins are chosen and licensed, how replisomes assemble during initiation, and how unwinding occurs during DNA replication.

Structural basis of RNA polymerase III transcription initiation.

RNA polymerase (Pol) III transcribes essential non-coding RNAs, including the entire pool of transfer RNAs, the 5S ribosomal RNA and the U6 spliceosomal RNA, and is often deregulated in cancer cells. The initiation of gene transcription by Pol III requires the activity of the transcription factor TFIIIB to form a transcriptionally active Pol III preinitiation complex (PIC). Here we present electron microscopy reconstructions of Pol III PICs at 3.4-4.0 Å and a reconstruction of unbound apo-Pol III at 3.1 Å. TFIIIB fully encircles the DNA and restructures Pol III. In particular, binding of the TFIIIB subunit Bdp1 rearranges the Pol III-specific subunits C37 and C34, thereby promoting DNA opening. The unwound DNA directly contacts both sides of the Pol III cleft. Topologically, the Pol III PIC resembles the Pol II PIC, whereas the Pol I PIC is more divergent. The structures presented unravel the molecular mechanisms underlying the first steps of Pol III transcription and also the general conserved mechanisms of gene transcription initiation.

Tankyrase Requires SAM Domain-Dependent Polymerization to Support Wnt-ß-Catenin Signaling.

The poly(ADP-ribose) polymerase (PARP) Tankyrase (TNKS and TNKS2) is paramount to Wnt-ß-catenin signaling and a promising therapeutic target in Wnt-dependent cancers. The pool of active ß-catenin is normally limited by destruction complexes, whose assembly depends on the polymeric master scaffolding protein AXIN. Tankyrase, which poly(ADP-ribosyl)ates and thereby destabilizes AXIN, also can polymerize, but the relevance of these polymers has remained unclear. We report crystal structures of the polymerizing TNKS and TNKS2 sterile alpha motif (SAM) domains, revealing versatile head-to-tail interactions. Biochemical studies informed by these structures demonstrate that polymerization is required for Tankyrase to drive ß-catenin-dependent transcription. We show that the polymeric state supports PARP activity and allows Tankyrase to effectively access destruction complexes through enabling avidity-dependent AXIN binding. This study provides an example for regulated signal transduction in non-membrane-enclosed compartments (signalosomes), and it points to novel potential strategies to inhibit Tankyrase function in oncogenic Wnt signaling.

ANZTCT practice statement: sinusoidal obstruction syndrome/veno-occlusive disease diagnosis and management.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is a life-threatening complication which can develop after haemopoietic stem cell transplantation (HSCT) and some antibody-drug conjugates. Several SOS/VOD diagnostic and management guidelines exist, with the most recent and refined being the European Society for Blood and Marrow Transplantation adult and paediatric guidelines. Timely diagnosis and effective management (including the availability of therapeutic options) significantly contribute to improved patient outcomes. In Australia and New Zealand, there is variability in clinical practice and access to SOS/VOD therapies. This review aims to summarise the current evidence for SOS/VOD diagnosis, prevention and treatment and to provide recommendations for SOS/VOD in the context of contemporary Australasian HSCT clinical practice.

Zebrafish as a model for cardiac disease; Cryo-EM structure of native cardiac thin filaments from Danio Rerio.

Actin, tropomyosin and troponin, the proteins that comprise the contractile apparatus of the cardiac thin filament, are highly conserved across species. We have used cryo-EM to study the three-dimensional structure of the zebrafish cardiac thin and actin filaments. With 70% of human genes having an obvious zebrafish orthologue, and conservation of 85% of disease-causing genes, zebrafish are a good animal model for the study of human disease. Our structure of the zebrafish thin filament reveals the molecular interactions between the constituent proteins, showing that the fundamental organisation of the complex is the same as that reported in the human reconstituted thin filament. A reconstruction of zebrafish cardiac F-actin demonstrates no deviations from human cardiac actin over an extended length of 14 actin subunits. Modelling zebrafish homology models into our maps enabled us to compare, in detail, the similarity with human models. The structural similarities of troponin-T in particular, a region known to contain a hypertrophic cardiomyopathy 'hotspot', confirm the suitability of zebrafish to study these disease-causing mutations.

Cryo-electron tomography of intact cardiac muscle reveals myosin binding protein-C linking myosin and actin filaments.

Myosin binding protein C (MyBP-C) is an accessory protein of the thick filament in vertebrate cardiac muscle arranged over 9 stripes of intervals of 430 Å in each half of the A-band in the region called the C-zone. Mutations in cardiac MyBP-C are a leading cause of hypertrophic cardiomyopathy the mechanism of which is unknown. It is a rod-shaped protein composed of 10 or 11 immunoglobulin- or fibronectin-like domains labelled C0 to C10 which binds to the thick filament via its C-terminal region. MyBP-C regulates contraction in a phosphorylation dependent fashion that may be through binding of its N-terminal domains with myosin or actin. Understanding the 3D organisation of MyBP-C in the sarcomere environment may provide new light on its function. We report here the fine structure of MyBP-C in relaxed rat cardiac muscle by cryo-electron tomography and subtomogram averaging of refrozen Tokuyasu cryosections. We find that on average MyBP-C connects via its distal end to actin across a disc perpendicular to the thick filament. The path of MyBP-C suggests that the central domains may interact with myosin heads. Surprisingly MyBP-C at Stripe 4 is different; it has weaker density than the other stripes which could result from a mainly axial or wavy path. Given that the same feature at Stripe 4 can also be found in several mammalian cardiac muscles and in some skeletal muscles, our finding may have broader implication and significance. In the D-zone, we show the first demonstration of myosin crowns arranged on a uniform 143 Å repeat.

Tranexamic acid at cesarean delivery: drug-error deaths.

The use of tranexamic acid for postpartum hemorrhage has entered obstetrical practice globally with the evidence-based expectation of saving lives. This improvement in the care of women with postpartum hemorrhage has come at a price. For the anesthetist, having tranexamic acid ampoules close at hand would seem an obvious strategy to facilitate its use during cesarean delivery, an important setting for severe hemorrhage. Tragically, we have identified a number of recent instances of inadvertent intrathecal administration of tranexamic acid instead of local anesthetic for spinal anesthesia. Reported cases of this catastrophic error seem to be increasing. The profound neurotoxicity of tranexamic acid causes rapid-onset convulsions, with mortality of 50%. How can these tragic errors be averted? Drug safety alerts have been issued by the US Food and Drug Administration and the World Health Organization, but that is not enough. We recommend extensive dissemination of information to raise awareness of this potential hazard, and local hospital protocols to ensure that tranexamic acid is stored separately from anesthetic drugs, preferably outside the operating room and with an auxiliary warning label. Implementation of safety strategies on a very large scale will be needed to ensure that the life-saving potential of tranexamic acid is not eclipsed by drug-error mortality.

Tranexamic acid at cesarean delivery: drug-error deaths.

The use of tranexamic acid for postpartum hemorrhage has entered obstetrical practice globally with the evidence-based expectation of saving lives. This improvement in the care of women with postpartum hemorrhage has come at a price. For the anesthetist, having tranexamic acid ampoules close at hand would seem an obvious strategy to facilitate its use during cesarean delivery, an important setting for severe hemorrhage. Tragically, we have identified a number of recent instances of inadvertent intrathecal administration of tranexamic acid instead of local anesthetic for spinal anesthesia. Reported cases of this catastrophic error seem to be increasing. The profound neurotoxicity of tranexamic acid causes rapid-onset convulsions, with mortality of 50%. How can these tragic errors be averted? Drug safety alerts have been issued by the US Food and Drug Administration and the World Health Organization, but that is not enough. We recommend extensive dissemination of information to raise awareness of this potential hazard, and local hospital protocols to ensure that tranexamic acid is stored separately from anesthetic drugs, preferably outside the operating room and with an auxiliary warning label. Implementation of safety strategies on a very large scale will be needed to ensure that the life-saving potential of tranexamic acid is not eclipsed by drug-error mortality.

A comprehensive study of the epidemiology of haematological malignancies in North Queensland.

BACKGROUND: There is an absence of clinically relevant epidemiological data in regional Australia pertaining to haematological malignancies. AIM: To determine the incidence and geographical variation of haematological malignancies in North Queensland using a clinically appropriate disease classification. METHODS: Retrospective, observational study of individual patient data records of all adults diagnosed with a haematological malignancy between 2005 and 2014 and residing within The Townsville Hospital Haematology catchment region. We report descriptive summaries, incidence rates and incidence-rate ratios of haematological malignancies by geographic regions. RESULTS: One thousand, five hundred and eighty-one haematological malignancies (69% lymphoid, 31% myeloid) were diagnosed over the 10-year study period. Descriptive data are presented for 58 major subtypes, as per the WHO diagnostic classification of tumours of haemopoietic and lymphoid tissues. The overall median age at diagnosis was 66 years with a male predominance (60%). We demonstrate a temporal increase in the incidence of haematological malignancies over the study period. We observed geographical variations in the age-standardised incidence rates per 100 000 ranging from 0.5 to 233.5. Our data suggest an increased incidence rate ratio for haematological malignancies in some postcodes within the Mackay area compared with other regions. CONCLUSION: The present study successfully reports on the incidence of haematological malignancies in regional Queensland using a clinically meaningful diagnostic classification system and identifies potential geographic hotspots. We advocate for such contemporary, comprehensive and clinically meaningful epidemiological data reporting of blood cancer diagnoses in wider Australia. Such an approach will have significant implications towards developing appropriate data-driven management strategies and public health responses for haematological malignancies.

Origin licensing requires ATP binding and hydrolysis by the MCM replicative helicase.

Loading of the six related Minichromosome Maintenance (MCM) proteins as head-to-head double hexamers during DNA replication origin licensing is crucial for ensuring once-per-cell-cycle DNA replication in eukaryotic cells. Assembly of these prereplicative complexes (pre-RCs) requires the Origin Recognition Complex (ORC), Cdc6, and Cdt1. ORC, Cdc6, and MCM are members of the AAA+ family of ATPases, and pre-RC assembly requires ATP hydrolysis. Here we show that ORC and Cdc6 mutants defective in ATP hydrolysis are competent for origin licensing. However, ATP hydrolysis by Cdc6 is required to release nonproductive licensing intermediates. We show that ATP binding stabilizes the wild-type MCM hexamer. Moreover, by analyzing MCM containing mutant subunits, we show that ATP binding and hydrolysis by MCM are required for Cdt1 release and double hexamer formation. This work alters our view of how ATP is used by licensing factors to assemble pre-RCs.

Management and implications of severe COVID-19 in pregnancy in the UK: data from the UK Obstetric Surveillance System national cohort.

INTRODUCTION: There is a lack of population level data on risk factors and impact of severe COVID-19 in pregnancy. The aims of this study were to determine the characteristics, and maternal and perinatal outcomes associated with severe COVID-19 in pregnancy compared with those with mild and moderate COVID-19 and to explore the impact of timing of birth. MATERIAL AND METHODS: This was a secondary analysis of a national, prospective cohort study. All pregnant women admitted to hospital in the UK with symptomatic SARS-CoV-2 from March 1, 2020 to October 31, 2021 were included. The severity of maternal infection (need for high flow or invasive ventilation, intensive care admission or died), pregnancy and perinatal outcomes, and the impact of timing of birth were analyzed using multivariable logistic regression. RESULTS: Of 4436 pregnant women, 13.9% (n = 616) had severe infection. Women with severe infection were more likely to be aged ≥30 years (adjusted odds ratio [aOR] aged 30-39 1.48, 95% confidence interval [CI] 1.20-1.83), be overweight or obese (aOR 1.73, 95% CI 1.34-2.25 and aOR 2.52 95% CI 1.97-3.23, respectively), be of mixed ethnicity (aOR 1.93, 95% CI 1.17-3.21) or have gestational diabetes (aOR 1.43, 95% CI 1.09-1.87) compared with those with mild or moderate infection. Women with severe infection were more likely to have a pre-labor cesarean birth (aOR 8.84, 95% CI 6.61-11.83), a very or extreme preterm birth (28-31+ weeks' gestation, aOR 18.97, 95% CI 7.78-14.85; <28 weeks' gestation, aOR 12.35, 95% CI 6.34-24.05) and their babies were more likely to be stillborn (aOR 2.51, 95% CI 1.35-4.66) or admitted to a neonatal unit (aOR 11.61, 95% CI 9.28-14.52). Of 112 women with severe infection who were discharged and gave birth at a later admission, the majority gave birth ≥36 weeks (85.7%), noting that three women in this group (2.7%) had a stillbirth. CONCLUSIONS: Severe COVID-19 in pregnancy increases the risk of adverse outcomes. Information to promote uptake of vaccination should specifically target those at greatest risk of severe outcomes. Decisions about timing of birth should be informed by multidisciplinary team discussion; however, our data suggest that women with severe infection who do not require early delivery have mostly good outcomes but that those with severe infection at term may warrant rapid delivery.

Cannabidiol for the Management of Endometriosis and Chronic Pelvic Pain.

OBJECTIVE: To review the available literature on the effect of cannabis-based products on the female reproductive system and establish whether there is any evidence that they benefit or harm patients with endometriosis and, therefore, whether there is sufficient evidence to recommend them. DATA SOURCES: An electronic-based search was performed in PubMed, Embase, and the Cochrane Database. Reference lists of articles retrieved were reviewed, and a gray literature search was also performed. METHODS OF STUDY SELECTION: The original database search yielded 264 articles from PubMed, Embase, and the Cochrane Database, of which 41 were included. One hundred sixty-one studies relating to gynecologic malignancy, conditions unrelated to endometriosis, or therapies unrelated to cannabis-based products were excluded. Twelve articles were included from a gray literature search and review of references. TABULATION, INTEGRATION, AND RESULTS: Most available evidence is from laboratory studies aiming to simulate the effects of cannabis-based products on preclinical endometriosis models. Some show evidence of benefit with cannabis-based products. However, results are conflicting, and the impact in humans cannot necessarily be extrapolated from these data. Few studies exist looking at the effect of cannabis or its derived products in women with endometriosis; the majority are in the form of surveys and are affected by bias. National guidance was also reviewed: at present, this dictates that cannabis-based products can only be prescribed for conditions in which there is clear published evidence of benefit and only when all other treatment options have been exhausted. CONCLUSION: Current treatment options for endometriosis often affect fertility and/or have undesirable side effects that impede long-term management. Cannabis-based products have been suggested as a novel therapeutic option that may circumvent these issues. However, there is a paucity of well-designed, robust studies and randomized controlled trials looking at their use in the treatment of endometriosis. In addition, cannabis use has a potential for harm in the long term, with a possible association with "cannabis use disorder," psychosis, and mood disturbances. At present, national guidance cannot recommend cannabis-based products to patients in the UK owing to lack of clear evidence of benefit. More comprehensive research into the impact of endocannabinoids in the context of endometriosis is required before their use can be recommended or prescribed.

Three-dimensional structure of the basketweave Z-band in midshipman fish sonic muscle.

Striated muscle enables movement in all animals by the contraction of myriads of sarcomeres joined end to end by the Z-bands. The contraction is due to tension generated in each sarcomere between overlapping arrays of actin and myosin filaments. At the Z-band, actin filaments from adjoining sarcomeres overlap and are cross-linked in a regular pattern mainly by the protein α-actinin. The Z-band is dynamic, reflected by the 2 regular patterns seen in transverse section electron micrographs; the so-called small-square and basketweave forms. Although these forms are attributed, respectively, to relaxed and actively contracting muscles, the basketweave form occurs in certain relaxed muscles as in the muscle studied here. We used electron tomography and subtomogram averaging to derive the 3D structure of the Z-band in the swimbladder sonic muscle of type I male plainfin midshipman fish (Porichthys notatus), into which we docked the crystallographic structures of actin and α-actinin. The α-actinin links run diagonally between connected pairs of antiparallel actin filaments and are oriented at an angle of about 25° away from the actin filament axes. The slightly curved and flattened structure of the α-actinin rod has a distinct fit into the map. The Z-band model provides a detailed understanding of the role of α-actinin in transmitting tension between actin filaments in adjoining sarcomeres.

Maternal and perinatal outcomes of pregnant women with SARS-CoV-2 infection at the time of birth in England: national cohort study.

BACKGROUND: Some studies have suggested that women with SARS-CoV-2 infection during pregnancy are at increased risk of adverse pregnancy and neonatal outcomes, but these associations are still not clear. OBJECTIVE: This study aimed to determine the association between SARS-CoV-2 infection at the time of birth and maternal and perinatal outcomes. STUDY DESIGN: This is a population-based cohort study in England. The inclusion criteria were women with a recorded singleton birth between May 29, 2020, and January 31, 2021, in a national database of hospital admissions. Maternal and perinatal outcomes were compared between pregnant women with a laboratory-confirmed SARS-CoV-2 infection recorded in the birth episode and those without. Study outcomes were fetal death at or beyond 24 weeks' gestation (stillbirth), preterm birth (<37 weeks' gestation), small for gestational age infant (small for gestational age; birthweight at the .05) in the rate of other maternal outcomes. The risk of neonatal adverse outcome (adjusted odds ratio, 1.45; 95% confidence interval, 1.27-1.66; P<.001), need for specialist neonatal care (adjusted odds ratio, 1.24; 95% confidence interval, 1.02-1.51; P=.03), and prolonged neonatal admission after birth (adjusted odds ratio, 1.61; 95% confidence interval, 1.49-1.75; P<.001) were all significantly higher for infants with mothers with laboratory-confirmed SARS-CoV-2 infection. When the analysis was restricted to pregnancies delivered at term (≥37 weeks), there were no significant differences in neonatal adverse outcome (P=.78), need for specialist neonatal care after birth (P=.22), or neonatal readmission within 4 weeks of birth (P=.05). Neonates born at term to mothers with laboratory-confirmed SARS-CoV-2 infection were more likely to have prolonged admission after birth (21.1% compared with 14.6%; adjusted odds ratio, 1.61; 95% confidence interval, 1.49-1.75; P<.001). CONCLUSION: SARS-CoV-2 infection at the time of birth is associated with higher rates of fetal death, preterm birth, preeclampsia, and emergency cesarean delivery. There were no additional adverse neonatal outcomes, other than those related to preterm delivery. Pregnant women should be counseled regarding risks of SARS-CoV-2 infection and should be considered a priority for vaccination.

A retrospective analysis of the prevalence and clinical outcomes of vitamin D deficiency in myeloma patients in tropical Australia.

PURPOSE: The aim of this descriptive study was to assess the prevalence of vitamin D deficiency in patients on active therapy for multiple myeloma in a tropical climate. We also tested for the association of vitamin D status on clinical outcomes. METHODS: This was a single centre, observational study performed in Townsville, Australia, which has a sunlight heavy, tropical climate. Patients on active therapy for multiple myeloma underwent testing of serum 25-hydroxyvitamin D (25(OH)D). Information on disease stage, skeletal morbidity and symptoms of peripheral neuropathy were collected from medical records and self-reported patient questionnaires. RESULTS: A total of 41 patients were included. With a median disease duration of 38 months, 27% were found to be vitamin D deficient. Patients with vitamin D deficiency had a higher likelihood of peripheral neuropathy compared with their non-vitamin D counterparts (73% vs. 33%, P = 0.03). Although those with vitamin D deficiency had more skeletal morbidity, this was not statistically significant (73% vs 50%, P = 0.19). Reduced 25(OH) D was associated with a poor performance status (P = 0.003). There was no association between vitamin D status and stage of myeloma. CONCLUSION: There is a relatively high prevalence of vitamin D deficiency in patients with myeloma in our study. This is despite a sunlight heavy, tropical climate. We report an association between vitamin D deficiency and peripheral neuropathy. Prospective interventional trials are required to further assess this.

Molecular model of the human 26S proteasome.

The 26S proteasome plays a fundamental role in eukaryotic homeostasis by undertaking the highly controlled degradation of a wide range of proteins, including key cellular regulators such as those controlling cell-cycle progression and apoptosis. Here we report the structure of the human 26S proteasome determined by cryo-electron microscopy and single-particle analysis, with secondary structure elements identified both in the 20S proteolytic core region and in the 19S regulatory particle. We have used this information together with crystal structures, homology models, and other biochemical information to construct a molecular model of the complete 26S proteasome. This model allows for a detailed description of the 20S core within the 26S proteasome and redefines the overall assignment of subunits within the 19S regulatory particle. The information presented here provides a strong basis for a mechanistic understanding of the 26S proteasome.

Women's perceptions of COVID-19 and their healthcare experiences: a qualitative thematic analysis of a national survey of pregnant women in the United Kingdom.

BACKGROUND: The aim of this national survey was to explore pregnant women's perceptions of COVID-19 and their healthcare experiences. METHODS: Through patient and public involvement, a questionnaire was developed and advertised via the BBC website, Twitter and other online media during May 2020. The findings were analysed by qualitative thematic analysis. Women who are currently pregnant, or who have delivered during the COVID-19 pandemic were invited to partake in a national online survey. RESULTS: One thousand four hundred fifty-one participants replied to the online questionnaire. Participants provided significant insight into the perceived barriers to seeking healthcare during this pandemic. These include 'not wanting to bother anyone', 'lack of wider support from allied healthcare workers' and the influence of the media. Other concerns included the use of virtual clinics antenatally and their acceptability to patients, the presence of birthing partners, and the way in which information is communicated about rapidly changing and evolving services. The influence of the media has also had a significant impact on the way women perceive hospital care in light of COVID-19 and for some, this has shaped whether they would seek help. CONCLUSIONS: This is the first ever reported study in the United Kingdom to explore pregnant women's perceptions of COVID-19 and their subsequent healthcare experiences. It has also provided insight into perceived barriers into seeking care as well as maternal concerns antenatally, intrapartum and postpartum.