Evaluating the transmission risk of SARS-CoV-2 from sewage pollution

The presence of SARS-CoV-2 in untreated sewage has been confirmed in many countries but its incidence and infection risk in contaminated waters is poorly understood. The River Thames in the UK receives untreated sewage from 57 Combined Sewer Overflows (CSOs), with many discharging dozens of times per year. This study investigated if such discharges provide a pathway for environmental transmission of SARS-CoV-2. Samples of wastewater, surface water, and sediment collected close to six CSOs on the River Thames were assayed over eight months for SARS-CoV-2 RNA and infectious virus. Bivalves were also sampled as an indicator species of viral bioaccumulation. Sediment and water samples from the Danube and Sava rivers in Serbia, where raw sewage is also discharged in high volumes, were assayed as a positive control. No evidence of SARS-CoV-2 RNA or infectious virus was found in UK samples, in contrast to RNA positive samples from Serbia. Furthermore, this study shows that infectious SARS-CoV-2 inoculum is stable in Thames water and sediment for <3 days, while SARS-CoV-2 RNA is detectable for at least seven days. This indicates that dilution of wastewater likely limits environmental transmission, and that detection of viral RNA alone is not an indication of pathogen spillover.

Natriuretic peptide referral thresholds and heart failure diagnosis: population-based cohort study

Background

Natriuretic peptide (NP) testing is recommended by both the European Society of Cardiology (ESC) and the National Institute for Health and Care Excellence (NICE) for people presenting with symptoms of heart failure (HF) in primary care. However, ESC and NICE guidelines suggest different NP referral thresholds: ESC recommend referral at a lower NP level (BNP≥35pg/ml / NT-proBNP≥125pg/ml) compared to NICE (BNP≥100pg/ml/NT-proBNP≥400pg/ml).

Purpose

We aimed to evaluate NP test performance for HF diagnosis for ESC and NICE guideline-defined thresholds.

Methods

Population-based cohort study using linked primary and secondary care data from the Clinical Practice Research Datalink in England between 1st January 2000 and 31st December 2018. Participants were adults aged 45 years and above with a NP result: 74,233 had a BNP and 155,347 had a NT-proBNP measurement. The main outcome measures were diagnostic performance of NP test (sensitivity, specificity, positive predictive value, negative predictive value) by threshold.

Results

A total of 229,580 patients had a NP test and 21,102 (9.2%) were diagnosed with HF. The ESC NT-proBNP threshold of 125pg/ml had a sensitivity of 94.6% (94.2 to 95.0) and specificity of 50.0% (49.7 to 50.3) compared to sensitivity of 81.7% (81.0 to 82.3) and specificity of 80.3% (80.0 to 80.5) for the NICE NT-proBNP 400pg/ml threshold. For both guidelines, nearly all patients with a NP level below the threshold did not have HF (negative predictive value ESC 98.9% (98.8 to 99.0) and NICE 97.7% (97.6 to 97.8). Similar performance was found for BNP.

Conclusions

The performance of NP testing is dependent on the guideline-specified threshold for referral. In 100 people with HF, using the NICE threshold would falsely reassure 18 patients, whereas the lower ESC threshold would miss just 5 people but twice as many patients would be referred for diagnostic assessment. The optimal NP threshold for referral for HF diagnosis will depend on the healthcare setting. The trade-off between missing HF cases and overwhelming diagnostic services needs to be determined at a national level.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute for Health Research

Prevalence of left-ventricular systolic dysfunction and heart failure in the Echocardiographic Heart of England Screening study: a population based study

BACKGROUND

Accurate data for prevalence rates for heart failure due to various causes, and for left-ventricular systolic dysfunction in all adults are unavailable. Our aim was to assess prevalence of left-ventricular systolic dysfunction and heart failure in a large representative adult population in England.

METHODS

Of 6286 randomly selected patients aged 45 years and older, 3960 (63%) participated in the study. They came from 16 randomly selected general practices. We assessed patients by history and examination, electrocardiography, and echocardiography. Prevalence of left-ventricular systolic dysfunction (defined as ejection fraction <40%) and heart failure was calculated for the overall population on the basis of strict criteria and, when necessary, adjudication by a panel.

FINDINGS

Left-ventricular systolic dysfunction was diagnosed in 72 (1.8% [95% CI 1.4-2.3]) participants, half of whom had no symptoms. Borderline left-ventricular function (ejection fraction 40-50%) was seen in 139 patients (3.5% [3.0-4.1]). Definite heart failure was seen in 92 (2.3%, [1.9-2.8]) and was associated with an ejection fraction of less than 40% in 38 (41%) patients, atrial fibrillation in 30 (33%), and valve disease in 24 (26%). Probable heart failure was seen in a further 32 (0.8% [0.6-1.1]) patients. In total, 124 (3.1% [2.6-3.7]) patients aged 45 years or older had definite or probable heart failure.

INTERPRETATION

Heart failure is often misdiagnosed or underdiagnosed in primary care. Our results suggest that assessment of left-ventricular function in patients with suspected heart failure could lead to more effective diagnosis and treatment of this disorder.

Helicobacter pylori-selective antibacterials based on inhibition of pyrimidine biosynthesis

We report the discovery of a class of pyrazole-based compounds that are potent inhibitors of the dihydroorotate dehydrogenase of Helicobacter pylori but that do not inhibit the cognate enzymes from Gram-positive bacteria or humans. In culture these compounds inhibit the growth of H. pylori selectively, showing no effect on other Gram-negative or Gram-positive bacteria or human cell lines. These compounds represent the first examples of H. pylori-specific antibacterial agents. Cellular activity within this structural class appears to be due to dihydroorotate dehydrogenase inhibition. Minor structural changes that abrogate in vitro inhibition of the enzyme likewise eliminate cellular activity. Furthermore, the minimum inhibitory concentrations of these compounds increase upon addition of orotate to the culture medium in a concentration-dependent manner, consistent with dihydroorotate dehydrogenase inhibition as the mechanism of cellular inhibition. The data presented here suggest that targeted inhibition of de novo pyrimidine biosynthesis may be a valuable mechanism for the development of antimicrobial agents selective for H. pylori.

Selective inhibition of bacterial dihydroorotate dehydrogenases by thiadiazolidinediones

Dihydroorotate dehydrogenase is a critical enzyme of de novo pyrimidine biosynthesis in prokaryotic and eukaryotic cells. Differences in the primary structure of the enzymes from Gram-positive and -negative bacteria and from mammals indicate significant structural divergence among these enzymes. We have identified a class of small molecules, the thiadiazolidinediones, that inhibit prototypical enzymes from Gram-positive and -negative bacteria, but are inactive against the human enzyme. The most potent compound in our collection functioned as a time-dependent irreversible inactivator of the bacterial enzymes with k(inact)/K(i) values of 48 and 500 M(-1) sec(-1) for the enzymes from Escherichia coli and Enterococcus faecalis, respectively. The data presented here indicate that it is possible to inhibit prokaryotic dihydroorotate dehydrogenases selectively while sparing the mammalian enzyme. Thus, this enzyme may represent a valuable target for the development of novel antibiotic compounds.

Identification of a novel inhibitor of mitogen-activated protein kinase kinase

The compound U0126 (1,4-diamino-2,3-dicyano-1, 4-bis[2-aminophenylthio]butadiene) was identified as an inhibitor of AP-1 transactivation in a cell-based reporter assay. U0126 was also shown to inhibit endogenous promoters containing AP-1 response elements but did not affect genes lacking an AP-1 response element in their promoters. These effects of U0126 result from direct inhibition of the mitogen-activated protein kinase kinase family members, MEK-1 and MEK-2. Inhibition is selective for MEK-1 and -2, as U0126 shows little, if any, effect on the kinase activities of protein kinase C, Abl, Raf, MEKK, ERK, JNK, MKK-3, MKK-4/SEK, MKK-6, Cdk2, or Cdk4. Comparative kinetic analysis of U0126 and the MEK inhibitor PD098059 (Dudley, D. T., Pang, L., Decker, S. J., Bridges, A. J., and Saltiel, A. R. (1995) Proc. Natl. Acad. Sci U. S. A. 92, 7686-7689) demonstrates that U0126 and PD098059 are noncompetitive inhibitors with respect to both MEK substrates, ATP and ERK. We further demonstrate that the two compounds bind to deltaN3-S218E/S222D MEK in a mutually exclusive fashion, suggesting that they may share a common or overlapping binding site(s). Quantitative evaluation of the steady state kinetics of MEK inhibition by these compounds reveals that U0126 has approximately 100-fold higher affinity for deltaN3-S218E/S222D MEK than does PD098059. We further tested the effects of these compounds on the activity of wild type MEK isolated after activation from stimulated cells. Surprisingly, we observe a significant diminution in affinity of both compounds for wild type MEK as compared with the deltaN3-S218E/S222D mutant enzyme. These results suggest that the affinity of both compounds is mediated by subtle conformational differences between the two activated MEK forms. The MEK affinity of U0126, its selectivity for MEK over other kinases, and its cellular efficacy suggest that this compound will serve as a powerful tool for in vitro and cellular investigations of mitogen-activated protein kinase-mediated signal transduction.