Lower hepatocellular carcinoma surveillance in metabolic dysfunction-associated steatotic liver disease: Impact on treatment eligibility.

BACKGROUND AND AIM: This study aimed to compare the determinants and impact of hepatocellular carcinoma (HCC) surveillance rates for people with metabolic dysfunction-associated steatotic liver disease (MASLD) versus other chronic liver diseases. METHODS: A dataset of HCC patients from a UK hospital (2007-2022) was analyzed. The Mann-Whitney U-test compared continuous variables. The χ2 and two-tailed Fisher exact tests compared categorical data. Regression modeling analyzed the impact of MASLD on the size and number of HCC nodules and curative treatment. The Cox proportional hazards model assessed the influence of MASLD on overall survival. RESULTS: A total of 176 of 687 (25.6%) HCC patients had MASLD. Fewer people with MASLD HCC were enrolled in HCC surveillance compared to non-MASLD HCC (38 [21.6%] vs 215 [42.1%], P < 0.001). Patients with MASLD HCC were less likely to have been under secondary care (n = 57 [32.4%] vs 259 [50.7%], P < 0.001) and less likely to have cirrhosis (n = 113 [64.2%] vs 417 [81.6%], P < 0.001). MASLD was associated with a 12.3-mm (95% confidence interval [CI] 10.8-14.0 mm) greater tumor diameter compared to people without MASLD (P = 0.002). Patients with MASLD HCC had 0.62 reduced odds (95% CI 0.43-0.91) of receiving curative treatment compared to non-MASLD HCC (P = 0.014). Overall survival was similar for patients with MASLD HCC versus non-MASLD HCC (hazard ratio 1.03, 95% CI 0.85-1.25, P = 0.748). CONCLUSION: Patients with MASLD are less likely to have been enrolled in HCC surveillance due to undiagnosed cirrhosis or presenting with non-cirrhotic HCC. Patients with MASLD HCC present with larger tumors and are less likely to receive curative treatment.

Dimeric Transmembrane Structure of the SARS-CoV-2 E Protein.

The SARS-CoV-2 E protein is a transmembrane (TM) protein with its N-terminus exposed on the external surface of the virus. At debate is its oligomeric state, let alone its function. Here, the TM structure of the E protein is characterized by oriented sample and magic angle spinning solid-state NMR in lipid bilayers and refined by molecular dynamics simulations. This protein was previously found to be a pentamer, with a hydrophobic pore that appears to function as an ion channel. We identify only a front-to-front, symmetric helix-helix interface, leading to a dimeric structure that does not support channel activity. The two helices have a tilt angle of only 6°, resulting in an extended interface dominated by Leu and Val sidechains. While residues Val14-Thr35 are almost all buried in the hydrophobic region of the membrane, Asn15 lines a water-filled pocket that potentially serves as a drug-binding site. The E and other viral proteins may adopt different oligomeric states to help perform multiple functions.

Dimeric Transmembrane Structure of the SARS-CoV-2 E Protein.

The SARS-CoV-2 E protein is a transmembrane (TM) protein with its N-terminus exposed on the external surface of the virus. Here, the TM structure of the E protein is characterized by oriented sample and magic angle spinning solid-state NMR in lipid bilayers and refined by molecular dynamics simulations. This protein has been found to be a pentamer, with a hydrophobic pore that appears to function as an ion channel. We identified only a symmetric helix-helix interface, leading to a dimeric structure that does not support channel activity. The two helices have a tilt angle of only 6°, resulting in an extended interface dominated by Leu and Val sidechains. While residues Val14-Thr35 are almost all buried in the hydrophobic region of the membrane, Asn15 lines a water-filled pocket that potentially serves as a drug-binding site. The E and other viral proteins may adopt different oligomeric states to help perform multiple functions.

Outcomes of National Survey of the Practice of Hepatocellular Carcinoma Surveillance.

Background & Aim: HCC has significantly improved outcomes when detected early. Guidelines recommend biannual surveillance with ultrasound (US) and/or AFP in at-risk individuals. This survey aimed to describe HCC surveillance adherence/practices amongst the NHS hospitals in the UK. Methods: An electronic survey was sent to 79 NHS hospitals via the British Association for the Study of the Liver distribution list. The responses were captured from July 2021 to January 2022. Centres were divided into hepato-pancreato-biliary (HPB) and non-HPB centres, depending on whether the hospital undertakes major liver surgeries. Results: A total of 39 (49.3%) centres responded: 15 HPB and 24 non-HPB centres from across the UK. HCC surveillance eligibility criteria were universally applied, but heterogeneous approaches occur outside these criteria. Eighty per cent of patients undergoing surveillance were estimated to have cirrhosis. Eighty-five per cent of centres do 6-monthly US and AFP requested by clinicians and liver clinical nurse specialists. Compliance was estimated at 80% but not routinely audited. In most centres, general sonographers and/or radiologists perform surveillance US scans without a standard reporting template, although structured reporting was viewed as desirable by the majority. Poor views on US are approached heterogeneously, with patients variably offered ongoing US, CT, or MRI with different protocols. Conclusion: Most responding NHS hospitals follow 6-monthly HCC surveillance guidance. Data recording is variable, with limited routine data collection regarding compliance, yield, and quality. Surveillance US is mostly performed by non-HPB specialists without standardised reporting. There is an inconsistent approach to poor views with US surveillance. Even in a universal healthcare system such as NHS, which is free at the point of care, delivery of HCC surveillance has not improved over the last decade and remains variable.

An Arg/Ala-rich helix in the N-terminal region of M. tuberculosis FtsQ is a potential membrane anchor of the Z-ring.

Mtb infects a quarter of the worldwide population. Most drugs for treating tuberculosis target cell growth and division. With rising drug resistance, it becomes ever more urgent to better understand Mtb cell division. This process begins with the formation of the Z-ring via polymerization of FtsZ and anchoring of the Z-ring to the inner membrane. Here we show that the transmembrane protein FtsQ is a potential membrane anchor of the Mtb Z-ring. In the otherwise disordered cytoplasmic region of FtsQ, a 29-residue, Arg/Ala-rich α-helix is formed that interacts with upstream acidic residues in solution and with acidic lipids at the membrane surface. This helix also binds to the GTPase domain of FtsZ, with implications for drug binding and Z-ring formation.

Cost of hepatocellular carcinoma to the national health service in England: a registry-based analysis.

OBJECTIVE: Hepatocellular carcinoma (HCC) incidence in the UK trebled between 1997 and 2017. With increasing numbers requiring treatment, understanding the likely impact on healthcare budgets can inform service planning and commissioning. The aim of this analysis was to use existing registry data to describe the direct healthcare costs of current treatments for HCC and estimate the impact on National Health Service (NHS) budgets. DESIGN: A retrospective data analysis based on the National Cancer Registration and Analysis Service cancer registry informed a decision-analytic model for England comparing patients by cirrhosis compensation status and those on palliative or curative treatment pathways. Potential cost drivers were investigated by undertaking a series of one-way sensitivity analyses. RESULTS: Between 1 January 2010 and 31 December 2016, 15 684 patients were diagnosed with HCC. The median cost per patient over 2 years was £9065 (IQR: £1965 to £20 491), 66% did not receive active therapy. The cost of HCC treatment for England over 5 years was estimated to be £245 million. CONCLUSION: The National Cancer Registration Dataset and linked data sets have enabled a comprehensive analysis of the resource use and costs of secondary and tertiary healthcare for HCC, providing an overview of the economic impact to the NHS England of treating HCC.

Major variation in hepatocellular carcinoma treatment and outcomes in England: a retrospective cohort study.

Objective: Hepatocellular carcinoma (HCC) is increasingly incident in England, while survival remains poor with regional disparities. We aimed to explore the differences in HCC treatment across different geographical regions and to examine the impact on cancer survival. Methods: Incident HCC cases and treatment were identified from the English Hospital Episode Statistics (2016-2017) and then a subset by National Health Service (NHS) regions. Treatment was grouped into curative, palliative and untreated. Median survival was estimated to date of death in the national statistics. Results: The median observed survival was 8.6 months (95% CI 7.5 to 9.9) across all 2160 HCC cases, 52.1 months (CI 50.5, not reached) in 449 (20.8%) treated with curative intent, 21.0 months (CI 18.5 to 24.5) after other cancer-specific treatment in 449 (20.8%), and 2.3 months (CI 2.1 to 2.6) in 1262 (58.4%) untreated. Across NHS regions, <50% of cases received treatment (30.4%-49.6%), while between 14.2% and 27.7% had curative treatment. The 3-year survival was similar (23.5%-29.7%), except in the London region (40.0%). Conclusion: Majority of HCC cases in England are untreated and survival remains low, with variation in outcomes in regions with similar incident rates. A deeper exploration of regional treatments and screening practice is required to improve early detection and survival.

Surprising Rigidity of Functionally Important Water Molecules Buried in the Lipid Headgroup Region.

Understanding water dynamics and structure is an important topic in biological systems. It is generally held in the literature that the interfacial water of hydrated phospholipids is highly mobile, in fast exchange with the bulk water ranging from the nano- to femtosecond timescale. Although nuclear magnetic resonance (NMR) is a powerful tool for structural and dynamic studies, direct probing of interfacial water in hydrated phospholipids is formidably challenging due to the extreme population difference between bulk and interfacial water. We developed a novel 17O solid-state NMR technique in combination with an ultra-high-field magnet (35.2 T) to directly probe the functionally important interfacial water. By selectively suppressing the dominant bulk water signal, we observed two distinct water species in the headgroup region of hydrated dimyristoylphosphatidylcholine (DMPC) lipid bilayers for the first time. One water species denoted as "confined water" is chemically and dynamically different from the bulk water (∼0.17 ppm downfield and a slightly shorter spin-lattice relaxation time). Another water species denoted as "bound water" has severely restricted motion and a distinct chemical shift (∼12 ppm upfield). Additionally, the bulk water is not as "free" as pure water, resulting from the fast exchange with the water molecules that weakly and transiently interact with the lipid choline groups. These new discoveries clearly indicate the existence of the interfacial water molecules that are relatively stable over the NMR timescale (on the order of milliseconds), providing an opportunity to characterize water dynamics on the millisecond or slower timescale in biomacromolecules.

Emulating Membrane Protein Environments─How Much Lipid Is Required for a Native Structure: Influenza S31N M2.

This report investigates the homotetrameric membrane protein structure of the S31N M2 protein from Influenza A virus in the presence of a high molar ratio of lipid. The structured regions of this protein include a single transmembrane helix and an amphipathic helix. Two structures of the S31N M2 conductance domain from Influenza A virus have been deposited in the Protein Data Bank (PDB). These structures present different symmetries about the channel main axis. We present new magic angle spinning and oriented sample solid-state NMR spectroscopic data for S31N M2 in liquid crystalline lipid bilayers using protein tetramer:lipid molar ratios ranging from 1:120 to 1:240. The data is consistent with an essentially 4-fold-symmetric structure very similar to the M2 WT structure that also has a single conformation for the four monomers, except at the His37 and Trp41 functional sites when characterized in samples with a high molar ratio of lipid. While detergent solubilization is well recognized today as a nonideal environment for small membrane proteins, here we discuss the influence of a high lipid to protein ratio for samples of the S31N M2 protein to stabilize an essentially 4-fold-symmetric conformation of the M2 membrane protein. While it is generally accepted that the chemical and physical properties of the native environment of membrane proteins needs to be reproduced judiciously to achieve the native protein structure, here we show that not only the character of the emulated membrane environment is important but also the abundance of the environment is important for achieving the native structure. This is a critical finding as a membrane protein spectroscopist's goal is always to generate a sample with the highest possible protein sensitivity while obtaining spectra of the native-like structure.

Halting the haematochezia.

An elderly gentleman with primary sclerosing cholangitis (PSC) was admitted with rectal bleeding, shown on flexible sigmoidoscopy to be arising from rectal varices, which bled despite endoscopic therapy with histoacryl glue. Therapeutic options were limited with surgery and transjugular intrahepatic portosystemic shunt deemed too high risk, and endovascular embolisation through interventional radiology was sought. Coil-assisted retrograde transvenous obliteration was used to good effect. This rare approach has advantages over balloon occlusion, avoiding long indwelling balloon time and risk of rupture or infection, as well as time efficiency.

Primary liver cancer in the UK: Incidence, incidence-based mortality, and survival by subtype, sex, and nation.

BACKGROUND & AIMS: The incidence of primary liver cancer (PLC) is increasing in Western Europe. To understand trends over time and the current burden in the UK, a detailed analysis of the epidemiology of PLC and its subtypes was conducted. METHODS: Data on PLCs diagnosed during 1997-2017 were obtained from population-based, nationwide registries in the UK. European age-standardised incidence (ASR) and incidence-based mortality rates (ASMR) per 100,000 person-years were calculated overall and by sex and UK-nation. Annual percentage change in rates was estimated using Joinpoint regression. One-, 2-, and 5-year age-standardised net survival was estimated. RESULTS: A total of 82,024 PLCs were diagnosed. Both hepatocellular carcinoma (HCC) incidence and mortality rates trebled (ASR 1.8-5.5 per 100,000, ASMR 1.3-4.0). The rate of increase appeared to plateau around 2014/2015. Scottish men consistently had the highest HCC incidence rates. PLC survival increased, driven by a substantial increase in the proportion that are HCC (as prognosis is better than other PLCs) and in HCC survival (change in 1-year survival 24-47%). Intrahepatic cholangiocarcinoma was the most common PLC in women and 1-year survival improved from 22.6% to 30.5%. CONCLUSIONS: PLC incidence has been increasing rapidly but, as most risk factors are modifiable, it is largely a preventable cancer. This rate of increase has slowed in recent years, possibly attributable to effective treatment for hepatitis C. As other risk factors such as obesity and diabetes remain prevalent in the UK, it is unlikely the considerable burden of this disease will abate. While improvements in survival have been made, over half of patients are not alive after 1 year, therefore further progress in prevention, early detection, and treatment innovation are needed. LAY SUMMARY: Many more people are getting liver cancer, particularly the subtype hepatocellular carcinoma, than 20 years ago. Men in Scotland are most likely to get liver cancer and to die from it. Survival after liver cancer diagnosis is getting longer but still less than half are alive after 1 year.

Fuzzy Association of an Intrinsically Disordered Protein with Acidic Membranes.

Many physiological and pathophysiological processes, including Mycobacterium tuberculosis (Mtb) cell division, may involve fuzzy membrane association by proteins via intrinsically disordered regions. The fuzziness is extreme when the conformation and pose of the bound protein and the composition of the proximal lipids are all highly dynamic. Here, we tackled the challenge in characterizing the extreme fuzzy membrane association of the disordered, cytoplasmic N-terminal region (NT) of ChiZ, an Mtb divisome protein, by combining solution and solid-state NMR spectroscopy and molecular dynamics simulations. While membrane-associated NT does not gain any secondary structure, its interactions with lipids are not random, but formed largely by Arg residues predominantly in the second, conserved half of the NT sequence. As NT frolics on the membrane, lipids quickly redistribute, with acidic lipids, relative to zwitterionic lipids, preferentially taking up Arg-proximal positions. The asymmetric engagement of NT arises partly from competition between acidic lipids and acidic residues, all in the first half of NT, for Arg interactions. This asymmetry is accentuated by membrane insertion of the downstream transmembrane helix. This type of semispecific molecular recognition may be a general mechanism by which disordered proteins target membranes.

Sequence-Dependent Correlated Segments in the Intrinsically Disordered Region of ChiZ.

How sequences of intrinsically disordered proteins (IDPs) code for their conformational dynamics is poorly understood. Here, we combined NMR spectroscopy, small-angle X-ray scattering (SAXS), and molecular dynamics (MD) simulations to characterize the conformations and dynamics of ChiZ1-64. MD simulations, first validated by SAXS and secondary chemical shift data, found scant α-helices or ß-strands but a considerable propensity for polyproline II (PPII) torsion angles. Importantly, several blocks of residues (e.g., 11-29) emerge as "correlated segments", identified by their frequent formation of PPII stretches, salt bridges, cation-π interactions, and sidechain-backbone hydrogen bonds. NMR relaxation experiments showed non-uniform transverse relaxation rates (R2s) and nuclear Overhauser enhancements (NOEs) along the sequence (e.g., high R2s and NOEs for residues 11-14 and 23-28). MD simulations further revealed that the extent of segmental correlation is sequence-dependent; segments where internal interactions are more prevalent manifest elevated "collective" motions on the 5-10 ns timescale and suppressed local motions on the sub-ns timescale. Amide proton exchange rates provides corroboration, with residues in the most correlated segment exhibiting the highest protection factors. We propose the correlated segment as a defining feature for the conformations and dynamics of IDPs.

Revealing weak histidine 15N homonuclear scalar couplings using Solid-State Magic-Angle-Spinning NMR spectroscopy.

The tautomeric structure and chemistry of the histidine imidazole ring play active roles in many structurally and functionally important proteins and polypeptides. While in NMR spectroscopy histidine chemical shifts (e.g. 15N, 13C, and 1H) have been commonly used to characterize the tautomeric structure, hydrogen bonding, and torsion angles, homonuclear 15N scalar couplings in histidine have rarely been reported. Here, we propose double spin-echo sequences to compare the observed signals with and without a 90° pulse between the two spin-echo periods, such that their signal ratio as a function of the echo time solely depends on homonuclear scalar couplings, allowing for measuring weak homonuclear scalar couplings without influence from transverse dephasing effects, thus capable of revealing hydrogen-bond mediated 15N-15N J-couplings that can provide direct and definitive evidence for the formation of N…H…N hydrogen-bonding associated with the imidazole ring. We used two 13C,15N labeled histidine samples recrystallized from solutions at pH 6.3 and pH 11.0 to demonstrate the feasibility of this method and reveal the existence of a weak two-bond scalar coupling between the Nδ1 and Nε2 sites in the histidine imidazole ring in three tautomeric states and the presence of a hydrogen-bond mediated scalar coupling between the Nδ1 site in the imidazole ring and the backbone Nα site in the histidine neutral τ and π states. Our results demonstrate that weak 15N homonuclear scalar couplings can be measured even when their values are less than their corresponding intrinsic natural linewidths, thus providing direct and definitive evidence for the formation of N…H…N hydrogen bonding that is associated with the histidine imidazole ring.

Functional stability of water wire-carbonyl interactions in an ion channel.

Water wires are critical for the functioning of many membrane proteins, as in channels that conduct water, protons, and other ions. Here, in liquid crystalline lipid bilayers under symmetric environmental conditions, the selective hydrogen bonding interactions between eight waters comprising a water wire and a subset of 26 carbonyl oxygens lining the antiparallel dimeric gramicidin A channel are characterized by 17O NMR spectroscopy at 35.2 T (or 1,500 MHz for 1H) and computational studies. While backbone 15N spectra clearly indicate structural symmetry between the two subunits, single site 17O labels of the pore-lining carbonyls report two resonances, implying a break in dimer symmetry caused by the selective interactions with the water wire. The 17O shifts document selective water hydrogen bonding with carbonyl oxygens that are stable on the millisecond timescale. Such interactions are supported by density functional theory calculations on snapshots taken from molecular dynamics simulations. Water hydrogen bonding in the pore is restricted to just three simultaneous interactions, unlike bulk water environs. The stability of the water wire orientation and its electric dipole leads to opposite charge-dipole interactions for K+ ions bound at the two ends of the pore, thereby providing a simple explanation for an ∼20-fold difference in K+ affinity between two binding sites that are ∼24 Šapart. The 17O NMR spectroscopy reported here represents a breakthrough in high field NMR technology that will have applications throughout molecular biophysics, because of the acute sensitivity of the 17O nucleus to its chemical environment.

Observation of the Imidazole-Imidazolium Hydrogen Bonds Responsible for Selective Proton Conductance in the Influenza A M2 Channel.

The integral membrane M2 protein is a 97-residue membrane protein that assembles as a tetramer to conduct protons at a slow rate (102-103/s) when activated by low pH. The proton conductance mechanism has been extensively debated in the literature, but it is accepted that the proton conductance is facilitated by hydrogen bonds involving the His37 residues. However, the hydrogen bonding partnership remains unresolved. Here, we report on the measurement of 15N-15N J-couplings of 15N His37-labeled full length M2 (M2FL) protein from Influenza A virus embedded in synthetic liquid crystalline lipid bilayers using two-dimensional J-resolved NMR spectroscopy. We experimentally observed the hydrogen-bond mediated J-couplings between Nδ1 and Nε2 of adjacent His37 imidazole rings, providing direct evidence for the existence of various imidazolium-imidazole hydrogen-bonding geometries in the histidine tetrad at low pH, thus validating the proton conduction mechanism in the M2FL protein by which the proton is transferred through the breaking and reforming of the hydrogen bonds between pairs of His37 residues.