APRIL limits atherosclerosis by binding to heparan sulfate proteoglycans.

Atherosclerotic cardiovascular disease causes heart attacks and strokes, which are the leading causes of mortality worldwide1. The formation of atherosclerotic plaques is initiated when low-density lipoproteins bind to heparan-sulfate proteoglycans (HSPGs)2 and become trapped in the subendothelial space of large and medium size arteries, which leads to chronic inflammation and remodelling of the artery wall2. A proliferation-inducing ligand (APRIL) is a cytokine that binds to HSPGs3, but the physiology of this interaction is largely unknown. Here we show that genetic ablation or antibody-mediated depletion of APRIL aggravates atherosclerosis in mice. Mechanistically, we demonstrate that APRIL confers atheroprotection by binding to heparan sulfate chains of heparan-sulfate proteoglycan 2 (HSPG2), which limits the retention of low-density lipoproteins, accumulation of macrophages and formation of necrotic cores. Indeed, antibody-mediated depletion of APRIL in mice expressing heparan sulfate-deficient HSPG2 had no effect on the development of atherosclerosis. Treatment with a specific anti-APRIL antibody that promotes the binding of APRIL to HSPGs reduced experimental atherosclerosis. Furthermore, the serum levels of a form of human APRIL protein that binds to HSPGs, which we termed non-canonical APRIL (nc-APRIL), are associated independently of traditional risk factors with long-term cardiovascular mortality in patients with atherosclerosis. Our data reveal properties of APRIL that have broad pathophysiological implications for vascular homeostasis.

A Robust and Low-Cost Sulfonated Hypercrosslinked Polymer for Atmospheric Water Harvesting.

The availability of freshwater is rapidly declining due to over-exploitation and climate change, with multiple parts of the globe already facing significant freshwater scarcity. Here, a sulfonated hypercrosslinked polymer able to repeatedly harvest significant amounts of water via direct air capture is reported. Water uptake from relative humidities as low as 10% is demonstrated, mimicking some of the harshest environments on Earth. A water harvesting device is used to show repeated uptake and harvesting without significant detriment to adsorbent performance. Desorption is triggered using simulated sunlight, presenting a low-energy route to water harvesting and adsorbent regeneration. The synthesis of sulfonated hypercrosslinked polymer requires only low-cost and readily available reagents, offering excellent potential for scale-up. Due to an almost limitless supply of water vapor from air in most regions around the globe, this approach can transform our ability to address water security concerns.

Effects of increased recirculation air rate and aircraft cabin occupancy on passengers' health and well-being - Results from a randomized controlled trial.

BACKGROUND: Aircraft cabins are special environments. Passengers sit in close proximity in a space with low pressure that they cannot leave. The cabin is ventilated with a mixture of outside and recirculated air. The volume of outside air impacts the carbon footprint of flying. Higher recirculation air rates could be considered to save energy and divert less kerosene from producing thrust. OBJECTIVES: To investigate whether higher recirculation air rates in aircraft cabins negatively affect passengers' health and well-being and if occupancy plays a role in this. METHODS: In a 2 (occupancy: full and half-occupied) X 4 (ventilation regime) factorial design with stratified randomization, participants were exposed in an aircraft segment in a low-pressure tube during a 4-h simulated flight. Ventilation regimes consisted of increasing proportions of recirculated air up to a maximum CO2 concentration of 4200 ppm. Participants rated comfort, health symptoms, and sleepiness multiple times. Heart rate (variability), as stress marker, was measured continuously. RESULTS: 559 persons representative of flight passengers regarding age (M = 42.7, SD = 15.9) and sex (283 men) participated. ANCOVA results showed hardly any effect of both factors on self-reported health symptoms, strong main effects of occupancy on comfort measures, and interaction effects for sleepiness and physiological stress parameters: Participants in the half-occupied cabin hardly reacted to increased recirculation air rates and show overall more favorable responses. Participants in the fully occupied cabin reported higher sleepiness and had stress reactions when the recirculation air rate was high. DISCUSSION: This large-scale RCT shows the importance of occupancy, a previously neglected factor in indoor air research. The proximity of other people seems to increase stress and exacerbate reactions to air quality. Further studies on causal pathways are needed to determine if recirculation air rates can be increased to reduce the carbon footprint of flying without detrimental effects on passengers.

Microvascular rarefaction in patients with cerebrovascular events.

Capillary density rarefaction and endothelial dysfunction contribute to chronic hypoperfusion and cerebral small vessel disease. Previous animal experiments revealed spatiotemporal microvascular remodeling directing post-stroke brain reorganization. We hypothesized that microcirculatory changes during acute cerebrovascular events could be reflected systemically and visualized sublingually. In a prospective observational trial in vivo sublingual sidestream darkfield videomicroscopy was performed in twenty-one patients with either acute stroke (n = 13 ischemic, n = 1 ischemic with hemorrhagic transformation and n = 2 hemorrhagic stroke) or transitory ischemic attacks (n = 5) within 24 h after hospital admission and compared to an age- and sex-matched control group. Repetitive measurements were performed on the third day and after one week. Functional and perfused total capillary density was rarefied in the overall patient group (3060 vs 3717 µm/mm2, p = 0.001 and 5263 vs 6550 µm/mm2, p = 0.002, respectively) and in patients with ischemic strokes (2897 vs. 3717 µm/mm2, p < 0.001 and 5263 vs. 6550 µm/mm2, p = 0.006, respectively) when compared to healthy controls. The perfused boundary region (PBR), which was measured as an inverse indicator of glycocalyx thickness, was markedly related to red blood cell (RBC) filling percentage (regarded as an estimate of microvessel perfusion) in the overall patient group (r = -0.843, p < 0.001), in patients with ischemic strokes (r = -0.82, p = 0.001) as well as in healthy volunteers (r = -0.845, p < 0.001). In addition, there were significant associations between platelet count or platelet aggregation values (as measured by whole blood impedance aggregometry) and microvascular parameters in the overall patient collective, as well as in patients with ischemic strokes. In conclusion, cerebrovascular events are associated with altered systemic microvascular perfusion.

Strain specific properties of Escherichia coli can prevent non-canonical amino acid misincorporation caused by scale-related process heterogeneities.

BACKGROUND: Escherichia coli is one of the most important hosts for production of recombinant proteins in biopharmaceutical industry. However, when selecting a suitable production strain, it is often not considered that a lot of different sub-species exist, which can differ in their genotypes and phenotypes. Another important development step is the scale-up of bioprocesses with the particular challenge that heterogeneities and gradients occur at production scale. These in turn can affect the production organism and can have negative impact on the process and the product quality. Therefore, researchers developed scale-down reactors, which are used to mimic manufacturing conditions in laboratory scale. The main objectives of this study were to determine the extent to which scale-related process inhomogeneities affect the misincorporation of non-canonical amino acids into the recombinant target protein, which is an important quality attribute, and whether strain specific properties may have an impact. RESULTS: We investigated two industrially relevant E. coli strains, BL21(DE3) and HMS174(DE3), which produced an antigen binding fragment (Fab). The cells were cultivated in high cell density fed-batch mode at laboratory scale and under scale-down conditions. We demonstrated that the two host strains differ significantly with respect to norleucine misincorporation into the target protein, especially under heterogeneous cultivation conditions in the scale-down reactor. No norleucine misincorporation was observed in E. coli BL21(DE3) for either cultivation condition. In contrast, norleucine incorporation into HMS174(DE3) was already detectable in the reference process and increased dramatically in scale-down experiments. Norleucine incorporation was not random and certain positions were preferred over others, even though only a single codon exists. Differences in biomass and Fab production between the strains during scale-down cultivations could be observed as well. CONCLUSIONS: This study has shown that E. coli BL21(DE3) is much more robust to scale-up effects in terms of norleucine misincorporation than the K12 strain tested. In this respect, BL21(DE3) enables better transferability of results at different scales, simplifies process implementation at production scale, and helps to meet regulatory quality guidelines defined for biopharmaceutical manufacturing.

Epidemiological trends of HBV and HDV coinfection among Viennese HIV+ patients.

BACKGROUND AND AIMS: Despite vaccination recommendations, hepatitis B (HBV) and D (HDV) coinfections are common in HIV+individuals. METHODS: HBV immunization status (anti-HBs) as well as HBV (HBsAg/HBV-DNA) and HDV (anti-HDV) coinfection rates were assessed in 1870 HIV+individuals at HIV diagnosis (baseline, BL) and last follow-up (FU). RESULTS: Sixty-eight (3.6%) HIV patients were never tested for HBV. At BL, 89/1802 (4.9%) HIV patients were HBV coinfected. Four hundred and fifteen (23.0%) showed virological HBV clearance [HBsAg(-)/anti-HBc(+)/anti-HBs(+)] and 210 (11.7%) presented with anti-HBc(+) only. Seven hundred and ten (39.4%) were HBV naïve [HBsAg(-)/anti-HBs(-)/anti-HBc(-)/HBV-DNA(-)], but only 378 (21.0%) received vaccinations with detectable anti-HBs(+) titres. Among the 89 HBV/HIV-coinfected patients, only 52 (58.4%) were tested for HDV: 11/49 (22.4%) had anti-HDV(+) and 3/12 (25.0%) showed HDV-RNA viraemia. During a median FU of 6.5 (IQR 7.2) years, 44 (4.6%) of the 953 retested BL HBV-negative patients acquired new HBV infection (including 15/304, 4.9% of vaccinated patients). Of the 89 patients, 22 (24.7%) patients cleared their HBsAg, resulting in 60/1625 (3.7%) HIV/HBV individuals at FU: 34 (56.7%) showed HBV-DNA suppression and 15 (25.0%) were HBV viraemic, while 12/89 (13.5%) remained without a FU test. Vaccinations induced anti-HBs(+) in 137 of the retested 649 (21.1%) BL HBV-naïve patients. CONCLUSION: HBV testing is well established among Viennese HIV+patients with HBV coinfection rates around 4%-5%. HBV vaccinations are insufficiently implemented since anti-HBs titres were detected in only 21.1% of HBV-naive HIV(+) patients and new HBV infections occurred in previously vaccinated patients. HDV testing is not systematically performed despite up to 25% of HIV/HBV patients may show HDV coinfection.

Recent outbreaks of severe hepatitis A virus infections in Vienna.

To explore the epidemiology and clinical course of hepatitis A virus (HAV) infections at the Vienna General Hospital. We retrospectively identified patients who were tested positive for HAV-IgM at the Vienna General Hospital form Q1/2008 to Q3/2018. Our definition of severe HAV infection was AST and/or ALT > 5 × above the upper limit of normal (ULN); and liver dysfunction as (i) hepatic encephalopathy or ammonia > 100 µmol/L, (ii) coagulopathy with INR > 1.5, or (iii) jaundice with bilirubin > 5 mg/dL. A total of 578 HAV-IgM (+) were identified, including 31 (5.4%) and 38 (6.6%) without and with liver dysfunction, respectively. A proportional increase in severe HAV cases with and without liver dysfunction occurred in 2016/2017 with (21.5% (vs. 8.0% in the years before; p < 0.001). Thirty-seven (53.6%) patients with severe HAV were hospitalized, 6 (9%) required ICU support, and one patient received liver transplantation within 30 days. Patients with severe HAV and liver dysfunction were more often male (60.5 vs. 43.1%, p = 0.055) and younger (31.5 vs. 63 years, p < 0.001) as compared with other HAV-IgM (+) cases. The observed increase of severe HAV infections in Vienna in 2017 among young males, coincided with a multinational HAV outbreak among MSM. Our data suggests a higher likelihood of severe courses of hepatitis A in MSM. Vaccination against HAV should be recommended for risk groups.

Cabin air quality on non-smoking commercial flights: A review of published data on airborne pollutants.

We reviewed 47 documents published 1967-2019 that reported measurements of volatile organic compounds (VOCs) on commercial aircraft. We compared the measurements with the air quality standards and guidelines for aircraft cabins and in some cases buildings. Average levels of VOCs for which limits exist were lower than the permissible levels except for benzene with average concentration at 5.9 ± 5.5 µg/m3 . Toluene, benzene, ethylbenzene, formaldehyde, acetaldehyde, limonene, nonanal, hexanal, decanal, octanal, acetic acid, acetone, ethanol, butanal, acrolein, isoprene and menthol were the most frequently measured compounds. The concentrations of semi-volatile organic compounds (SVOCs) and other contaminants did not exceed standards and guidelines in buildings except for the average NO2 concentration at 12 ppb. Although the focus was on VOCs, we also retrieved the data on other parameters characterizing cabin environment. Ozone concentration averaged 38 ppb below the upper limit recommended for aircraft. The outdoor air supply rate ranged from 1.7 to 39.5 L/s per person and averaged 6.0 ± 0.8 L/s/p (median 5.8 L/s/p), higher than the minimum level recommended for commercial aircraft. Carbon dioxide concentration averaged 1315 ± 232 ppm, lower than what is permitted in aircraft and close to what is permitted in buildings. Measured temperatures averaged 23.5 ± 0.8°C and were generally within the ranges recommended for avoiding thermal discomfort. Relative humidity averaged 16% ± 5%, lower than what is recommended in buildings.

Hepatitis C Virus RNA Is Commonly Detectable in Rectal and Nasal Fluids of Patients With High Viremia.

BACKGROUND: Increasing numbers of hepatitis C virus (HCV) infections among men who have sex with men (MSM) are being observed in the Western world. The actual routes of HCV transmission during high-risk sex practices and associated drug use remain poorly understood. METHODS: Forty-seven patients with HCV were prospectively enrolled. Rectal and nasal swabs were collected to quantify HCV-RNA levels within rectal and nasal fluids. Contamination by occult rectal bleeding was excluded by guaiac paper test. Risk behavior was assessed by standardized questionnaires. RESULTS: Median age was 41.9 years, 89% were HIV positive (+) (42/47) and 85% (40/47) were male, 58% (23/40) of whom were MSM. Acute HCV infection was diagnosed in 32% (15/47) ,with all patients being HIV+MSM and 93% (14/15) having a documented history of sexually transmitted disease. Thirty-three (70%) patients had ≥1 HCV+ swab sample (HCV+SS; 48%, 22/46 rectal; 62%, 29/47 nasal), and contamination with blood was excluded in all patients. Individuals with HCV+SS had significantly higher serum HCV-RNA levels than patients with HCV-negative SS (6.28 [IQR, 0.85] log IU/mL vs 4.08 [2.45] log IU/mL; P < .001). Using ROC-curve analysis, serum HCV-RNA cutoffs for ruling in/out any HCV+SS were established at 6.02 log IU/mL and 4.02 log IU/mL, respectively. CONCLUSIONS: HCV-RNA is commonly detectable in rectal and nasal fluids of both HIV+ and HIV-negative HCV patients with high serum HCV-RNA, independently of the suspected route of HCV transmission. Accordingly, high-risk sex practices and sharing of nasal drug-sniffing "tools" might be important HCV transmission routes, especially in patients with high serum HCV-RNA.

Epidemiological trends in HCV transmission and prevalence in the Viennese HIV+ population.

BACKGROUND & AIMS: Human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfection is common in people who inject drugs (PWIDs). Recently, 'high-risk' behaviour among men who have sex with men (MSM) has emerged as another main route of HCV transmission. We analysed temporal trends in HCV epidemiology in a cohort of Viennese HIV+ patients. METHODS: Hepatitis C virus parameters were recorded at HIV diagnosis (baseline [BL]) and last visit (follow-up [FU]) for all HIV+ patients attending our HIV clinic between January 2014 and December 2016. Proportions of HIV+ patients with anti-HCV(+) and HCV viraemia (HCV-RNA(+)) at BL/FU were assessed and stratified by route of transmission. RESULTS: In all, 1806/1874 (96.4%) HIV+ patients were tested for HCV at BL. Anti-HCV(+) was detected in 93.2% (276/296) of PWIDs and in 3.7% (31/839) of MSM. After a median FU of 6.9 years, 1644 (91.0%) patients underwent FU HCV-testing: 167 (90.3%) of PWIDs and 49 (6.7%) of MSM showed anti-HCV(+). Among 208 viraemic HCV-RNA(+) patients at BL, 30 (14.4%) had spontaneously cleared HCV, 76 (36.5%) achieved treatment-induced eradication and 89 (42.8%) remained HCV-RNA(+) at last FU. Among 1433 initially HCV-naive patients, 45 (3.5%) acquired de-novo HCV infection (11.1% PWIDs/80.0% MSM; incidence rate (IR) 0.004%; 95% confidence interval [CI] 0.0%-0.022%) and 14 had HCV reinfections (85.7% PWIDs/14.3% other; IR 0.001%; 95% CI 0.0%-0.018%) during a median FU of 6.7 years (interquartile range 7.4). CONCLUSION: Hepatitis C virus testing was successfully implemented in the Viennese HIV(+) patients. Anti-HCV(+) prevalence remained stable in HIV+ PWIDs but almost doubled in HIV+ MSM. De-novo HCV infection occurred mostly in MSM, while HCV reinfections were mainly observed in PWIDs. HCV treatment uptake was suboptimal with 42.8% remaining HCV-RNA(+) at FU.

Carotid ultrasound investigation as a prognostic tool for patients with diabetes mellitus.

BACKGROUND: Experimental and clinical data indicate a major influence of diabetes on atherogenesis. We aimed to assess whether the effect of diabetes on long-term mortality in asymptomatic patient with carotid stenosis is contingent upon the degree of the carotid atherosclerotic burden. METHODS: 1065 patients with neurological asymptomatic carotid atherosclerosis as evaluated by duplex sonography were prospectively followed for cause-specific mortality. RESULTS: During a median of 11.8 years, a total of 549 deaths, including 362 cardiovascular deaths, were recorded. Diabetes and glycohemoglobin A1c (Hba1c) levels were significantly associated with mortality. Diabetes displayed an independent risk for all-cause (adjusted HR 1.62; 95% CI 1.35-1.94) and cardiovascular death (adjusted HR 1.75, 95% CI 1.40-2.19). The adjusted hazard ratio per increase of 1% of Hba1c levels was 1.21 (P < 0.01) for all-cause and 1.31 (P < 0.01) for cardiovascular mortality, respectively. Patients with diabetes mellitus and a higher degree of carotid stenosis and were at great risk of adverse outcome. Only 21% of the asymptomatic diabetic patients with carotid narrowing over 50% survived, whereas 62% of the patients without diabetes and with carotid atherosclerosis below 50% were still alive after 12-years of follow-up. The high risk for all-cause and cardiovascular death of these patients remained significant after adjustment for various established cardiovascular risk factors in multivariable regression analysis (adjusted hazard ratio 2.4, P < 0.001; compared to patients without diabetes and < 50% carotid atherosclerosis). CONCLUSION: Diabetic patients with carotid stenosis ≥ 50% are at exceptional high risk for all-cause and cardiovascular death. Thus, routinely ultrasound investigation of the carotid arteries might be a valuable prognostic tool for patients with diabetes mellitus.

The prognostic value of serum amyloid A for long-term mortality among patients with subclinical carotid atherosclerosis.

BACKGROUND AND PURPOSE: Despite extensive research in the last decade, the role of serum amyloid A (SAA) in atherogenesis remains highly controversial. The aim of this study was therefore to assess whether SAA is associated with long-term mortality in patients with subclinical carotid artery disease. METHODS: One thousand sixty-five patients with neurological asymptomatic carotid atherosclerosis as evaluated by duplex sonography were prospectively followed for cause-specific mortality. RESULTS: During a median of 11.8 years, a total of 549 deaths, including 362 cardiovascular deaths, were recorded. Patients who died within the follow-up period had significantly higher baseline SAA serum levels compared to those who survived (12.9 vs 9.5 mg/dL; P < 0.001). In univariable Cox regression analysis, the risk of all-cause and cardiovascular mortality significantly increased in patients with elevated serum levels of SAA (crude hazard ratio for cardiovascular mortality per increase of 1 SD of SAA levels was 1.14, 95% CI 1.08-1.22], P < 0.0001). However, SAA lost its significance after adjusting for high-sensitivity C-reactive protein (hsCRP), suggesting that SAA might not be directly associated with atherogenesis, but rather be a mere reflection of the individual patient's inflammatory status. CONCLUSIONS: Serum amyloid A is not independently associated with (cardiovascular) mortality in patients with subclinical carotid atherosclerosis.

Acute HIV Infection Results in Subclinical Inflammatory Cardiomyopathy.

The impact of excess viral RNA on myocardial function and morphology in the setting of acute human immunodeficiency virus (HIV) infection remains unknown. In this study, 49 patients with acute HIV infection showed increased levels of N-terminal prohormone of brain natriuretic peptide, a surrogate of myocardial function, which decreased with viral suppression and normalization of systemic inflammation (79 pg/mL vs 28 pg/mL; P < .001). A comparable change was seen with levels of troponin T, a marker of morphologic myocardial damage (4.9 ng/L vs 1.5 ng/L; P < .001). In conclusion, we observed significant functional and morphological myocardial impairment during acute HIV infection, fueled by inflammatory activation and extensive viral replication, resulting in a reversible subclinical inflammatory cardiomyopathy.

Better together: synergy in nanocellulose blends.

Cellulose nanopapers have gained significant attention in recent years as large-scale reinforcement for high-loading cellulose nanocomposites, substrates for printed electronics and filter nanopapers for water treatment. The mechanical properties of nanopapers are of fundamental importance for all these applications. Cellulose nanopapers can simply be prepared by filtering a suspension of nanocellulose, followed by heat consolidation. It was already demonstrated that the mechanical properties of cellulose nanopapers can be tailored by the fineness of the fibrils used or by modifying nanocellulose fibrils for instance by polymer adsorption, but nanocellulose blends remain underexplored. In this work, we show that the mechanical and physical properties of cellulose nanopapers can be tuned by creating nanopapers from blends of various grades of nanocellulose, i.e. (mechanically refined) bacterial cellulose or cellulose nanofibrils extracted from never-dried bleached softwood pulp by chemical and mechanical pre-treatments. We found that nanopapers made from blends of two or three nanocellulose grades show synergistic effects resulting in improved stiffness, strength, ductility, toughness and physical properties.This article is part of a discussion meeting issue 'New horizons for cellulose nanotechnology'.

Energy conservation by oxidation of formate to carbon dioxide and hydrogen via a sodium ion current in a hyperthermophilic archaeon.

Thermococcus onnurineus NA1 is known to grow by the anaerobic oxidation of formate to CO2 and H2, a reaction that operates near thermodynamic equilibrium. Here we demonstrate that this reaction is coupled to ATP synthesis by a transmembrane ion current. Formate oxidation leads to H(+) translocation across the cytoplasmic membrane that then drives Na(+) translocation. The ion-translocating electron transfer system is rather simple, consisting of only a formate dehydrogenase module, a membrane-bound hydrogenase module, and a multisubunit Na(+)/H(+) antiporter module. The electrochemical Na(+) gradient established then drives ATP synthesis. These data give a mechanistic explanation for chemiosmotic energy conservation coupled to formate oxidation to CO2 and H2. Because it is discussed that the membrane-bound hydrogenase with the Na(+)/H(+) antiporter module are ancestors of complex I of mitochondrial and bacterial electron transport these data also shed light on the evolution of ion transport in complex I-like electron transport chains.

Impact of phase estimation on single-channel speech separation based on time-frequency masking.

Time-frequency masking is a common solution for the single-channel source separation (SCSS) problem where the goal is to find a time-frequency mask that separates the underlying sources from an observed mixture. An estimated mask is then applied to the mixed signal to extract the desired signal. During signal reconstruction, the time-frequency-masked spectral amplitude is combined with the mixture phase. This article considers the impact of replacing the mixture spectral phase with an estimated clean spectral phase combined with the estimated magnitude spectrum using a conventional model-based approach. As the proposed phase estimator requires estimated fundamental frequency of the underlying signal from the mixture, a robust pitch estimator is proposed. The upper-bound clean phase results show the potential of phase-aware processing in single-channel source separation. Also, the experiments demonstrate that replacing the mixture phase with the estimated clean spectral phase consistently improves perceptual speech quality, predicted speech intelligibility, and source separation performance across all signal-to-noise ratio and noise scenarios.

Na+ transport by the A1AO-ATP synthase purified from Thermococcus onnurineus and reconstituted into liposomes.

The ATP synthase of many archaea has the conserved sodium ion binding motif in its rotor subunit, implying that these A1AO-ATP synthases use Na(+) as coupling ion. However, this has never been experimentally verified with a purified system. To experimentally address the nature of the coupling ion, we have purified the A1AO-ATP synthase from T. onnurineus. It contains nine subunits that are functionally coupled. The enzyme hydrolyzed ATP, CTP, GTP, UTP, and ITP with nearly identical activities of around 40 units/mg of protein and was active over a wide pH range with maximal activity at pH 7. Noteworthy was the temperature profile. ATP hydrolysis was maximal at 80 °C and still retained an activity of 2.5 units/mg of protein at 45 °C. The high activity of the enzyme at 45 °C opened, for the first time, a way to directly measure ion transport in an A1AO-ATP synthase. Therefore, the enzyme was reconstituted into liposomes generated from Escherichia coli lipids. These proteoliposomes were still active at 45 °C and coupled ATP hydrolysis to primary and electrogenic Na(+) transport. This is the first proof of Na(+) transport by an A1AO-ATP synthase and these findings are discussed in light of the distribution of the sodium ion binding motif in archaea and the role of Na(+) in the bioenergetics of archaea.