A placental model of SARS-CoV-2 infection reveals ACE2-dependent susceptibility and differentiation impairment in syncytiotrophoblasts.

SARS-CoV-2 infection causes COVID-19. Several clinical reports have linked COVID-19 during pregnancy to negative birth outcomes and placentitis. However, the pathophysiological mechanisms underpinning SARS-CoV-2 infection during placentation and early pregnancy are not clear. Here, to shed light on this, we used induced trophoblast stem cells to generate an in vitro early placenta infection model. We identified that syncytiotrophoblasts could be infected through angiotensin-converting enzyme 2 (ACE2). Using a co-culture model of vertical transmission, we confirmed the ability of the virus to infect syncytiotrophoblasts through a previous endometrial cell infection. We further demonstrated transcriptional changes in infected syncytiotrophoblasts that led to impairment of cellular processes, reduced secretion of HCG hormone and morphological changes vital for syncytiotrophoblast function. Furthermore, different antibody strategies and antiviral drugs restore these impairments. In summary, we have established a scalable and tractable platform to study early placental cell types and highlighted its use in studying strategies to protect the placenta.

Establishment of CT diagnostic reference levels (DRLs) for a Singapore healthcare cluster.

INTRODUCTION: The use of computed tomography (CT) in healthcare institutions has increased rapidly in recent years. The Singapore Health Services (SingHealth) cluster of healthcare institutions has taken the first step in establishing a local cluster-wide CT Diagnostic Reference Levels (DRL) in Singapore. CT dose data from each institution were collected through two primary dosimetry metrics: volume CT dose index (CTDIvol measured in mGy) and dose-length product (DLP measured in mGy.cm). METHODS: Data from 19 CT scanners in seven institutions under one of Singapore healthcare cluster were retrospectively collected and analysed. The five common adult CT examinations analysed were CT Brain (non-contrast enhanced), CT Chest (IV contrast enhanced), CT Kidney-Ureter-Bladder (CT KUB, non-contrast enhanced), CT Pulmonary Angiogram (CT PA, IV contrast enhanced) and CT Abdomen-Pelvis (CT AP, IV contrast enhanced, single phase). Median CTDIvol and DLP values for the five CT examinations from each institution were derived, with the cluster DRLs determined as the 75th percentile of the distribution of the institution median dose values. RESULTS: A total of 2413 dose data points were collected over a six-month period from June to November 2020. The cluster CT DRLs for the five CT examinations were determined to be 47 mGy and 820 mGy.cm for CT Brain, 5.4 mGy and 225 mGy.cm for CT Chest, 6.7 mGy and 248 mGy.cm for CT PA, 4.6 mGy and 190 mGy.cm for CT KUB and 6.9 mGy and 349 mGy.cm for CT AP. CONCLUSION: The establishment of the cluster CT DRLs provided individual institutions with a better understanding if their CT doses are unusually high or low, while emphasising that these DRLs are not meant as hard dose limits or constraints to follow strictly.

Simulating and Optimising Quantum Thermometry Using Single Photons.

A classical thermometer typically works by exchanging energy with the system being measured until it comes to equilibrium, at which point the readout is related to the final energy state of the thermometer. A recent paper noted that with a quantum thermometer consisting of a single spin/qubit, temperature discrimination is better achieved at finite times rather than once equilibration is essentially complete. Furthermore, preparing a qubit thermometer in a state with quantum coherence instead of an incoherent one improves its sensitivity to temperature differences. Implementing a recent proposal for efficiently emulating an arbitrary quantum channel, we use the quantum polarisation state of individual photons as models of "single-qubit thermometers" which evolve for a certain time in contact with a thermal bath. We investigate the optimal thermometer states for temperature discrimination, and the optimal interaction times, confirming that there is a broad regime where quantum coherence provides a significant improvement. We also discuss the more practical question of thermometers composed of a finite number of spins/qubits (greater than one), and characterize the performance of an adaptive protocol for making optimal use of all the qubits.

Polypoid endometriosis of post vaginal fornix: utility of MRI imaging of pelvis with diffusion weighted imaging for diagnosis.

Polypoid endometriosis is an uncommon variant of endometriosis which can mimic malignancy due to its presentation as masses. We present a case of polypoid endometriosis which simulated cervical malignancy both on clinical examination and on computed tomography (CT) scanning and discuss how magnetic resonance (MR) imaging, in particular Diffusion Weighted Imaging (DWI), can help to distinguish this condition from true malignancy and avoid invasive surgery.

Stronger Limits on Hypothetical Yukawa Interactions in the 30-8000 nm Range.

We report the results of new differential force measurements between a test mass and rotating source masses of gold and silicon to search for forces beyond Newtonian gravity at short separations. The technique employed subtracts the otherwise dominant Casimir force at the outset and, when combined with a lock-in amplification technique, leads to a significant improvement (up to a factor of 10^{3}) over existing limits on the strength (relative to gravity) of a putative force in the 40-8000 nm interaction range.

Pernicious anaemia presenting as hyperpigmentation.

An adult East Asian woman presented with sudden onset of hyperpigmented macules on her oral mucosal surfaces, palms and soles, in association with hypoguesia and loss of weight. This was found to be associated with underlying severe vitamin B12 deficiency secondary to pernicious anaemia.

Human isolates of Listeria monocytogenes in Sweden during half a century (1958-2010).

Isolates of Listeria monocytogenes (n = 932) isolated in Sweden during 1958-2010 from human patients with invasive listeriosis were characterized by serotyping and pulsed-field gel electrophoresis (PFGE) (AscI). Of the 932 isolates, 183 different PFGE types were identified, of which 83 were each represented by only one isolate. In all, 483 serovar 1/2a isolates were distributed over 114 PFGE types; 90 serovar 1/2b isolates gave 32 PFGE types; 21 serovar 1/2c isolates gave nine PFGE types; three serovar 3b isolates gave one PFGE type; and, 335 serovar 4b isolates gave 31 PFGE types. During the 1980s in Sweden, several serovar 4b cases were associated with the consumption of European raw soft cheese. However, as cheese-production hygiene has improved, the number of 4b cases has decreased. Since 1996, serovar 1/2a has been the dominant L. monocytogenes serovar in human listeriosis in Sweden. Therefore, based on current serovars and PFGE types, an association between human cases of listeriosis and the consumption of vacuum-packed gravad and cold-smoked salmon is suggested.

Altered secretory leukocyte protease inhibitor expression in the uterine decidua of tubal compared with intrauterine pregnancy.

BACKGROUND: The role of the innate immune system in tubal implantation remains undefined. This study compared expression of two key mediators of innate immunity, secretory leukocyte protease inhibitor (SLPI) and elafin, in the uterine decidua of women with intrauterine and tubal pregnancies. METHODS: Uterine decidua was collected from women (18-45 years) undergoing surgical termination of pregnancy (n = 7), surgical management of spontaneous abortion (n = 6) and tubal pregnancy (n = 10). Using quantitative RT-PCR and immunohistochemistry, mRNA and protein expression patterns of SLPI and elafin were compared. RESULTS: Relative SLPI mRNA expression was significantly higher in decidua of women with tubal pregnancy (12.37 +/- 2.66) compared with spontaneous abortion (5.09 +/- 2.22, P < 0.0185). There was no difference demonstrated in elafin mRNA expression. SLPI and elafin protein expression were demonstrated in the decidual leukocyte populations and epithelium. There was no obvious qualitative difference in levels of SLPI and elafin protein expression or their distribution in the uterine decidua of women with termination of pregnancy, spontaneous abortion or tubal pregnancy. CONCLUSIONS: Herein we demonstrate novel differences in gene expression of uterine decidua of tubal pregnancy compared with spontaneous abortion thereby contributing further to current knowledge of mechanisms involved in extrauterine implantation. The altered expression of SLPI may be a consequence of, or predispose to, tubal pregnancy.

More than one variant of Listeria monocytogenes isolated from each of two human cases of invasive listeriosis.

Two variants of Listeria monocytogenes were isolated from blood cultures from each of two patients with listeriosis. Each variant displayed a two-band difference in DNA profile from the other by pulsed-field gel electrophoresis. Although this difference in profile is insufficient to distinguish clearly between the variants, the possibility of co-infection with different strains of L. monocytogenes needs to be considered. We suggest that more than one colony should be selected for molecular typing to aid interpretation during investigation of the sources and routes of Listeria infection.

Causes behind a human cheese-borne outbreak of gastrointestinal listeriosis.

In a previous paper, we reported an outbreak of gastrointestinal listeriosis due to consumption of fresh cheese made from raw milk and manufactured on a summer farm. The aim of the present study was to investigate why the cheese harbored Listeria monocytogenes. To our knowledge, this is the first documented outbreak of listeriosis caused by raw milk cheese where the human epidemic strain has been cultured from a dairy animal, whose milk has been used for cheese production. The conditions on a summer farm can hardly fulfil the requirements for hygienic and strictly controlled conditions necessary for safe processing of fresh cheese.

Survival of Listeria monocytogenes in wilted and additive-treated grass silage.

Grass was field-dried to 3 different dry matter (DM) levels (200, 430 and 540 g/kg) and inoculated with 10(6)-10(7) cfu/g of a Listeria monocytogenes strain sharing a phagovar occasionally involved in foodborne outbreaks of listeriosis. Formic acid (3 ml/kg) or lactic acid bacteria (8 x 10(5)/g) with cellulolytic enzymes were applied only to forages with low and intermediate DM levels. Forages were ensiled in laboratory silos (1700 ml) and were stored at 25 degrees C for 30 or 90 days. After 90 days of storage, L. monocytogenes could not be detected in any silo, except one with the high dry matter grass without additive. After 30 days of storage, between 10(2) and 10(6) cfu L. monocytogenes/g silage were isolated from the untreated silages. Increasing the DM content from 200 to 540 g/kg did not reduce listeria counts possibly because of the lower production of fermentation acids (higher pH). In silages treated with additives, counts of L. monocytogenes were always lower than in silages without additive. In wet silages (DM 200 g/kg) both additives were effective, but in the wilted silages (DM 430 g/kg) only the bacterial additive reduced listeria counts below detection level. Listeria counts were highly correlated to silage pH (r = 0.92), the concentration of lactic acid (r = -0.80) and the pooled amount of undissociated acids (r = -0.83).

Febrile gastroenteritis after eating on-farm manufactured fresh cheese--an outbreak of listeriosis?

An outbreak of febrile gastroenteritis affected consumers of on-farm manufactured dairy products from a summer farm in Sweden. Symptoms included diarrhoea, fever, stomach cramps and vomiting in 88, 60, 54 and 21% of cases identified. The median incubation period was 31 h. A cohort study with 33 consumers showed an attack rate of 52% and an association between the total amount of product eaten and illness (P=0.07). Twenty-seven of 32 (84%) stool samples cultured for Listeria monocytogenes tested positive, although there was no association between clinical disease and the isolation of L. monocytogenes. In addition, gene sequences for VTEC and ETEC were detected in 6 and 1 subjects, respectively. Bacteriological analysis of cheese samples revealed heavy contamination with L. monocytogenes and coagulase positive staphylococci in all of them and gene markers for VTEC in one of them. Molecular profiles for L. monocytogenes isolated from dairy products, stool samples and an abscess from 1 patient who developed septic arthritis were identical. Results of both microbiological and epidemiological analyses point to L. monocytogenes as the most likely cause of this outbreak. The finding of markers for VTEC in some humans and cheese samples means that a mixed aetiology at least in some cases cannot be conclusively ruled out.

A listeriosis patient infected with two different Listeria monocytogenes strains.

Normally, only one isolate of Listeria monocytogenes from a case of listeriosis is subjected to characterization. Here we show that two isolates from different sites of the body were not the same strain. Such a phenomenon may not have any clinical relevance, although it may confuse the epidemiologist trying to match infection source with infection target.

Pyrosequencing as a method for grouping of Listeria monocytogenes strains on the basis of single-nucleotide polymorphisms in the inlB gene.

By using pyrosequencing (i.e., sequencing by synthesis) 106 strains of different serovars of Listeria monocytogenes were rapidly grouped into four categories based on nucleotide variations at positions 1575 and 1578 of the inlB gene. Strains of serovars 1/2a and 1/2c constituted one group, and strains of serovars 1/2b and 3b constituted another group, whereas serovar 4b strains were separated into two groups.

Localization of yeast telomeres to the nuclear periphery is separable from transcriptional repression and telomere stability functions.

The left telomere of Saccharomyces chromosome VII was often localized near the nuclear periphery, even in cells lacking the silencing proteins Sir3 or Hdf1. This association was lost in late mitotic cells and when transcription was induced through the telomeric tract. Although in silencing competent cells there was no correlation between the fraction of cells in which a telomeric gene was repressed and the fraction of cells in which it was localized to the periphery, no condition was found where the telomere was both silenced and away from the periphery. We conclude that localization of a telomere to the nuclear periphery is not sufficient for transcriptional repression nor does it affect the stability function of yeast telomeres.

Structure-function analysis of the tobacco mosaic virus resistance gene N.

The tobacco N gene is a member of the Toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class of plant resistance (R) genes and confers resistance to tobacco mosaic virus (TMV). We investigated the importance of specific domains of N in inducing TMV resistance, by examining various N deletion and point mutations that introduce single amino acid substitution mutants in vivo. Our deletion analysis suggests that the TIR, NBS, and LRR domains play an indispensable role in the induction of resistance responses against TMV. We show that amino acids conserved among the Toll/IL-1R/plant R gene TIR domain and NBS-containing proteins play a critical role in N-mediated TMV resistance. Some loss-of-function N alleles such as the TIR deletion and point mutations in the NBS (G216A/E/V/R, G218R, G219D, K222E/N, and T223A/N) interfere with the wild-type N function and behave like dominant negative mutations. These F(1) plants mount a hypersensitive response (HR) that is indistinguishable from that of the wild-type N plants, yet TMV was able to move systemically, causing a systemic hypersensitive response (SHR). Many amino acid substitutions in the TIR, NBS, and LRR domains of N lead to a partial loss-of-function phenotype. These mutant plants mount delayed HR compared with the wild-type N plants and fail to contain the virus to the infection site. In addition, some partial loss-of-function alleles (W82S/A, W141S/A, G218V/S, and G219V) interfere with the wild-type N function, leading to SHR. The partial loss-of-function and dominant negative mutant alleles described in this report will be useful in furthering our understanding of the TIR-NBS-LRR class of R genes.

Listeria monocytogenes in faeces from clinically healthy dairy cows in Sweden.

Faecal samples from 102 clinically healthy dairy cows, representing 34 farms in the Swedish province of Uppsala, were analysed for the presence of Listeria spp. using an enrichment procedure. Listeria monocytogenes was isolated from six (6%) and L. innocua from 2 (2%) cows. From each of the 6 samples positive for L. monocytogenes, 5 isolates were further characterised by restriction enzyme analysis using the 3 enzymes Apa I, Sma I, and Asc I, followed by pulsed-field gel electrophoresis. Three of the L. monocytogenes positive cows lived at the same farm, and they all harboured the same clonal type. One of these 3 cows also harboured a further clonal type of L. monocytogenes. The fact that one of the cows harboured 2 different clonal types of L. monocytogenes is important from an epidemiological point of view when routes of infection are to be investigated.