N6-methyladenosine in poly(A) tails stabilize VSG transcripts.

RNA modifications are important regulators of gene expression1. In Trypanosoma brucei, transcription is polycistronic and thus most regulation happens post-transcriptionally2. N6-methyladenosine (m6A) has been detected in this parasite, but its function remains unknown3. Here we found that m6A is enriched in 342 transcripts using RNA immunoprecipitation, with an enrichment in transcripts encoding variant surface glycoproteins (VSGs). Approximately 50% of the m6A is located in the poly(A) tail of the actively expressed VSG transcripts. m6A residues are removed from the VSG poly(A) tail before deadenylation and mRNA degradation. Computational analysis revealed an association between m6A in the poly(A) tail and a 16-mer motif in the 3' untranslated region of VSG genes. Using genetic tools, we show that the 16-mer motif acts as a cis-acting motif that is required for inclusion of m6A in the poly(A) tail. Removal of this motif from the 3' untranslated region of VSG genes results in poly(A) tails lacking m6A, rapid deadenylation and mRNA degradation. To our knowledge, this is the first identification of an RNA modification in the poly(A) tail of any eukaryote, uncovering a post-transcriptional mechanism of gene regulation.

Cell-to-Cell Heterogeneity in Trypanosomes.

Recent developments in single-cell and single-molecule techniques have revealed surprising levels of heterogeneity among isogenic cells. These advances have transformed the study of cell-to-cell heterogeneity into a major area of biomedical research, revealing that it can confer essential advantages, such as priming populations of unicellular organisms for future environmental stresses. Protozoan parasites, such as trypanosomes, face multiple and often hostile environments, and to survive, they undergo multiple changes, including changes in morphology, gene expression, and metabolism. But why does only a subset of proliferative cells differentiate to the next life cycle stage? Why do only some bloodstream parasites undergo antigenic switching while others stably express one variant surface glycoprotein? And why do some parasites invade an organ while others remain in the bloodstream? Building on extensive research performed in bacteria, here we suggest that biological noise can contribute to the fitness of eukaryotic pathogens and discuss the importance of cell-to-cell heterogeneity in trypanosome infections.

RAP1 is essential for silencing telomeric variant surface glycoprotein genes in Trypanosoma brucei.

Trypanosoma brucei expresses variant surface glycoprotein (VSG) genes in a strictly monoallelic fashion in its mammalian hosts, but it is unclear how this important virulence mechanism is enforced. Telomere position effect, an epigenetic phenomenon, has been proposed to play a critical role in VSG regulation, yet no telomeric protein has been identified whose disruption led to VSG derepression. We now identify tbRAP1 as an intrinsic component of the T. brucei telomere complex and a major regulator for silencing VSG expression sites (ESs). Knockdown of tbRAP1 led to derepression of all VSGs in silent ESs, but not VSGs located elsewhere, and resulted in stronger derepression of genes located within 10 kb from telomeres than genes located further upstream. This graduated silencing pattern suggests that telomere integrity plays a key role in tbRAP1-dependent silencing and VSG regulation.

Endoscopic cyanoacrylate injection for massive bleeding from a ruptured pseudocyst.

Arterial bleeding is a dreadful late complication of acute pancreatitis that usually mandates emergent endovascular embolization or surgery. We present the case of a massive arterial bleeding resulting from fistulization of a pseudocyst to the stomach, which was successfully managed by endoscopic injection of cyanoacrylate.

Trypanosoma brucei triggers a broad immune response in the adipose tissue.

Adipose tissue is one of the major reservoirs of Trypanosoma brucei parasites, the causative agent of sleeping sickness, a fatal disease in humans. In mice, the gonadal adipose tissue (AT) typically harbors 2-5 million parasites, while most solid organs show 10 to 100-fold fewer parasites. In this study, we tested whether the AT environment responds immunologically to the presence of the parasite. Transcriptome analysis of T. brucei infected adipose tissue revealed that most upregulated host genes are involved in inflammation and immune cell functions. Histochemistry and flow cytometry confirmed an increasingly higher number of infiltrated macrophages, neutrophils and CD4+ and CD8+ T lymphocytes upon infection. A large proportion of these lymphocytes effectively produce the type 1 effector cytokines, IFN-γ and TNF-α. Additionally, the adipose tissue showed accumulation of antigen-specific IgM and IgG antibodies as infection progressed. Mice lacking T and/or B cells (Rag2-/-, Jht-/-), or the signature cytokine (Ifng-/-) displayed a higher parasite load both in circulation and in the AT, demonstrating the key role of the adaptive immune system in both compartments. Interestingly, infections of C3-/- mice showed that while complement system is dispensable to control parasite load in the blood, it is necessary in the AT and other solid tissues. We conclude that T. brucei infection triggers a broad and robust immune response in the AT, which requires the complement system to locally reduce parasite burden.

Factors Influencing Performance of Cholangioscopy-Guided Lithotripsy Including Available Different Technologies: A Prospective Multicenter Study with 94 Patients.

BACKGROUND: Peroral cholangioscopy (POC)-guided lithotripsy is an effective treatment for difficult biliary stones. A clear definition of factors associated with the efficacy of POC-guided lithotripsy in one session and the performance of electrohydraulic lithotripsy (EHL) and laser lithotripsy (LL) have not clearly emerged. METHODS: This was a non-randomized prospective multicenter study of all consecutive patients who underwent POC lithotripsy (using EHL and/or LL) for difficult biliary stones. The primary endpoint of the study was the number of sessions needed to achieve complete ductal clearance and the factors associated with this outcome. Secondary endpoints included the evaluated efficacies of LL and EHL. RESULTS: Ninety-four patients underwent 113 procedures of EHL or LL. Complete ductal clearance was obtained in 93/94 patients (98.94%). In total, 80/94 patients (85.11%) achieved stone clearance in a single session. In the multivariate analysis, stone size was independently associated with the need for multiple sessions to achieve complete ductal clearance (odds ratio = 1.146, 95% confidence interval: 1.055-1.244; p = 0.001). Using ROC curves and the Youden index, 22 mm was found to be the optimal cutoff for stone size (95% confidence interval: 15.71-28.28; p < 0.001). The majority of the patients (62.8%) underwent LL in the first session. Six patients failed the first session with EHL after using two probes and therefore were crossed over to LL, obtaining ductal clearance in a single additional session with a single LL fiber. EHL was significantly associated with a larger number of probes (2.0 vs. 1.02) to achieve ductal clearance (p < 0.01). The mean procedural time was significantly longer for EHL than for LL [72.1 (SD 16.3 min) versus 51.1 (SD 10.5 min)] (p < 0.01). CONCLUSIONS: POC is highly effective for difficult biliary stones. Most patients achieved complete ductal clearance in one session, which was significantly more likely for stones < 22 mm. EHL was significantly associated with the need for more probes and a longer procedural time to achieve ductal clearance.

African trypanosomes expressing multiple VSGs are rapidly eliminated by the host immune system.

Trypanosoma brucei parasites successfully evade the host immune system by periodically switching the dense coat of variant surface glycoprotein (VSG) at the cell surface. Each parasite expresses VSGs in a monoallelic fashion that is tightly regulated. The consequences of exposing multiple VSGs during an infection, in terms of antibody response and disease severity, remain unknown. In this study, we overexpressed a high-mobility group box protein, TDP1, which was sufficient to open the chromatin of silent VSG expression sites, to disrupt VSG monoallelic expression, and to generate viable and healthy parasites with a mixed VSG coat. Mice infected with these parasites mounted a multi-VSG antibody response, which rapidly reduced parasitemia. Consequently, we observed prolonged survival in which nearly 90% of the mice survived a 30-d period of infection with undetectable parasitemia. Immunodeficient RAG2 knock-out mice were unable to control infection with TDP1-overexpressing parasites, showing that the adaptive immune response is critical to reducing disease severity. This study shows that simultaneous exposure of multiple VSGs is highly detrimental to the parasite, even at the very early stages of infection, suggesting that drugs that disrupt VSG monoallelic expression could be used to treat trypanosomiasis.

Needle knife fistulotomy in flat and diverticular papillae: Is it time for redemption?

BACKGROUND: European Society of Gastrointestinal Endoscopy (ESGE) recommends needle-knife fistulotomy (NKF) as the preferred precut technique in cases when standard cannulation techniques fail. Despite scarce scientific evidence, flat and diverticular papillae are thought not to be ideal for NKF, as they are associated with poor outcomes. The present study aimed to determine the outcomes of the use of NKF in relation to flat and intradiverticular papillae. METHODS: This prospective multicenter study enrolled consecutive patients, evidencing naïve flat (group A, n = 49) or diverticular papilla (group B, n = 28), who underwent NKF after failure of standard cannulation techniques. Diverticular morphology was subdivided into intradiverticular (group B1, n = 14) and diverticular border papillae (group B2, n = 14), using a previously validated endoscopic classification of the major papilla. The success of biliary cannulation at initial endoscopic retrograde cholangiopancreatography (ERCP), overall biliary cannulation, overall cannulation time, and the rate of adverse events were assessed in the study. RESULTS: The initial cannulation rates were 93.9%, 64.3% and 71.4% for group A, B1, and B2, respectively (P = 0.005); overall cannulation rates after a second ERCP were 98.0%, 92.9% and 85.7%, respectively (P = 0.134). Adverse events occurred in 11.7% of patients, with post-ERCP pancreatitis (PEP) being the most common adverse event (10.4%). Although there was a trend towards a higher incidence of PEP in flat papillae, univariate and multivariate analyses did not show any significant relationship between pancreatitis and trainee involvement, papillary morphology, nor overall cannulation time. CONCLUSIONS: Although flat papillae are associated with high success rates of biliary cannulation using NKF, the rate of PEP is not negligible. NKF is feasible in diverticular papillae, but it is associated with a modest success rate in the initial ERCP.

Sclerotherapy using 2 % polidocanol foam in the treatment of hemorrhoidal disease - a single-center experience.

Elastic banding and sclerotherapy are the two most commonly performed instrumental therapies in the treatment of symptomatic internal hemorrhoids. Promising results have been shown with sclerotherapy using 2 % polidocanol foam. The present study aimed to evaluate the efficacy and safety of polidocanol foam in the treatment of symptomatic internal hemorrhoids.

Risk factors for the emergence of multidrug-resistant organisms in liver cirrhosis.

BACKGROUND: Multidrug-resistant organisms (MDROs) are a reality that can alter the paradigm of treatment and prevention of infection in patients with liver cirrhosis (LC). OBJECTIVE: Identify risk factors for the occurrence of MDROs in patients with LC. PATIENTS AND METHODS: Prospective study from October 2017 to March 2018 in consecutively hospitalized patients with decompensated LC with infection. Blood, urine and ascitic fluid cultures were analyzed. A p-value ≤0.05 was considered statistically significant. RESULTS: MDROs isolated in 18 of 52 episodes of infection. MDROs were associated with the use of proton pump inhibitors (PPIs) (p=0.0312), antibiotic therapy in the last 90 days (p=0.0033) and discharge within preceding 30 days or current hospitalization above 48h (p=0.0082). There was higher 90-day mortality in patients with MDROs infection (71.4% versus 35.7%, p=0.0316). CONCLUSION: MDROs infections were prevalent in this cohort and associated with 90-day mortality. Use of PPIs and antibiotics increased the risk of MDROs infections, suggesting that its prescription should be restricted to formal indication. Hospitalization was associated with the onset of MDROs, so LC patients should stay at the hospital the least possible. It is relevant to investigate other factors predisposing to the emergence of these microorganisms, in order to prevent it.

Trypanosoma brucei infection protects mice against malaria.

Sleeping sickness and malaria are parasitic diseases with overlapping geographical distributions in sub-Saharan Africa. We hypothesized that the immune response elicited by an infection with Trypanosoma brucei, the etiological agent of sleeping sickness, would inhibit a subsequent infection by Plasmodium, the malaria parasite, decreasing the severity of its associated pathology. To investigate this, we established a new co-infection model in which mice were initially infected with T. brucei, followed by administration of P. berghei sporozoites. We observed that a primary infection by T. brucei significantly attenuates a subsequent infection by the malaria parasite, protecting mice from experimental cerebral malaria and prolonging host survival. We further observed that an ongoing T. brucei infection leads to an accumulation of lymphocyte-derived IFN-γ in the liver, limiting the establishment of a subsequent hepatic infection by P. berghei sporozoites. Thus, we identified a novel host-mediated interaction between two parasitic infections, which may be epidemiologically relevant in regions of Trypanosoma/Plasmodium co-endemicity.

Outcomes of single-endoscopist-performed needle-knife fistulotomy for selective biliary access in 842 consecutive patients: learning curve and changes over a 14-year period in a retrospective study.

BACKGROUND AND AIMS: Needle-knife fistulotomy (NKF) has emerged as the preferred precut technique. From a late strategy, NKF has shifted to an early rescue technique and has been used recently as a primary method for biliary access. It is unknown how these changes have affected NKF outcomes. We analyzed the outcomes of NKF over time in a large cohort of patients. METHODS: Multicenter retrospective cohort study of 842 patients who underwent NKF for biliary access between 2006 and 2019. Patients were divided into four study periods according to a late or early cannulation strategy and to the use of post-ERCP pancreatitis prophylaxis (Period 1-Period 4). We assessed outcomes of NKF, learning curves and shifts over time. RESULTS: Bile duct access was obtained in 88.0% of the patients. The initial cannulation rate increased significantly from 77.5% in P1 to 92.0% in P4 (p < .001). An endoscopist can obtain 80% success rate after performing 100 NKF procedures (95% CI: 0.79-0.86) and a 95% success rate after 830 procedures (95% CI: 0.92-0.98). Adverse events and pancreatitis were observed in 6.5% and 4.9% of patients respectively. The rate of pancreatitis was not significantly different during the 4 periods (p = .190). A decline in the pancreatitis rate was observed from 2006 until 2016 (no trainees) and then an increase until 2019 (trainees involved). The presence of trainees increased the rate of pancreatitis in the last period by 9.9%. CONCLUSIONS: The success of NKF has increased significantly over the years, initially in a rapid manner and then more slowly. It is associated with a low rate of complications, which tend to decrease with experience. The involvement of trainees is associated with an increased rate of pancreatitis.

Intravital imaging of host-parasite interactions in skin and adipose tissues.

Intravital microscopy allows the visualisation of how pathogens interact with host cells and tissues in living animals in real time. This method has enabled key advances in our understanding of host-parasite interactions under physiological conditions. A combination of genetics, microscopy techniques, and image analysis have recently facilitated the understanding of biological phenomena in living animals at cellular and subcellular resolution. In this review, we summarise findings achieved by intravital microscopy of the skin and adipose tissues upon infection with various parasites, and we present a view into possible future applications of this method.

A complex case of low-phospholipid-associated cholelithiasis syndrome.

The low-phospholipid-associated cholelithiasis (LPAC) syndrome is a form of symptomatic and recurring cholelithiasis occurring in young adults, associated with mutations in the ABCB4 gene. It is a clinical syndrome characterized by at least two of the following criteria: age at onset of biliary symptoms below 40 years, intrahepatic echogenic foci or microlithiasis and recurrence of biliary symptoms after cholecystectomy. In the rare cases progressing to end-stage liver disease, a liver transplant may be indicated. We report a case of a 40-year-old female patient with clinical criteria for LPAC syndrome and with ABCB4 gene mutation. She had a complex history of choledocholithiasis recurrence despite treatment with ursodeoxycholic acid and multiple therapeutic endoscopic retrograde cholangiopancreatography, and she developed portal vein thrombosis.

Endoscopic therapy in disconnected duct syndrome: re-connecting the duct.

We report the case of a 61-year-old male patient with a history of acute necrotizing biliary pancreatitis and a disconnected duct syndrome. He underwent transgastric drainage using a luminal apposing metal stent and transgastric necrosectomy with complete resolution of the necrosis. A pancreatic fistula was identified during pancreatography and a pancreatic plastic stent was placed in order to manage the disconnected duct syndrome. The tip of the pancreatic stent could be seen inside the pancreatic collection, which is an unusual finding. There was a resolution of the collection and the pancreatic stent was removed.

Cinnamic Acid Conjugates in the Rescuing and Repurposing of Classical Antimalarial Drugs.

Cinnamic acids are compounds of natural origin that can be found in many different parts of a wide panoply of plants, where they play the most diverse biological roles, often in a conjugated form. For a long time, this has been driving Medicinal Chemists towards the investigation of the therapeutic potential of natural, semi-synthetic, or fully synthetic cinnamic acid conjugates. These efforts have been steadily disclosing promising drug leads, but a wide chemical space remains that deserves to be further explored. Amongst different reported approaches, the combination or conjugation of cinnamic acids with known drugs has been addressed in an attempt to produce either synergistic or multi-target action. In this connection, the present review will focus on efforts of the past decade regarding conjugation with cinnamic acids as a tool for the rescuing or the repurposing of classical antimalarial drugs, and also on future perspectives in this particular field of research.

Sensory analysis and fatty acid profile of specialty coffees stored in different packages.

The conservation of the quality of special coffees depends on the storage conditions. Therefore, new technologies for the packaging of grains need to be studied. This work was carried out with the objective of evaluating the effect of different packages on the quality of the stored coffee. The free fatty acid profile, fat acidity and sensory characteristics of the grains were analyzed during storage. The coffees were stored for 12 months in 8 packaging types. Coffee stored in jute bags differed mainly due to the higher values of fat acidity and lower scores in sensory analysis. The high-barrier packages were more efficient in the storage of the coffee beans since they presented the lowest deterioration indicators, represented by the low values of fat acidity, free fatty acids and higher scores in the sensorial evaluation.

A transcription-independent epigenetic mechanism is associated with antigenic switching in Trypanosoma brucei.

Antigenic variation in Trypanosoma brucei relies on periodic switching of variant surface glycoproteins (VSGs), which are transcribed monoallelically by RNA polymerase I from one of about 15 bloodstream expression sites (BES). Chromatin of the actively transcribed BES is depleted of nucleosomes, but it is unclear if this open conformation is a mere consequence of a high rate of transcription, or whether it is maintained by a transcription-independent mechanism. Using an inducible BES-silencing reporter strain, we observed that chromatin of the active BES remains open for at least 24 hours after blocking transcription. This conformation is independent of the cell-cycle stage, but dependent upon TDP1, a high mobility group box protein. For two days after BES silencing, we detected a transient and reversible derepression of several silent BESs within the population, suggesting that cells probe other BESs before commitment to one, which is complete by 48 hours. FACS sorting and subsequent subcloning confirmed that probing cells are switching intermediates capable of returning to the original BES, switch to the probed BES or to a different BES. We propose that regulation of BES chromatin structure is an epigenetic mechanism important for successful antigenic switching.

Modified continuity equation using left ventricular outflow tract three-dimensional imaging for aortic valve area estimation.

PURPOSE: Aortic valve area (AVA) is usually estimated by the continuity equation (CE) in which the left ventricular outflow tract (LVOT) area is calculated assuming a circular shape. This study aimed to compare measurements of LVOT area using standard 2D transthoracic echocardiography (2DTTE), 3D transesophageal echocardiography (3DTEE), and multidetector computed tomography (MDCT) and assess their relative impact on AVA estimated by the CE. METHODS AND RESULTS: We prospectively enrolled 60 patients with severe aortic stenosis (AS) referred for transcatheter aortic valve replacement (TAVR) who systematically underwent 2DTTE, 3DTEE, and MDCT. Mean LVOT areas obtained by 2DTTE (3.28±0.66 cm2 ) and 3DTEE (3.95±0.90 cm2 ) were significantly underestimated when compared to the mean MDCT LVOT area (4.31±0.99 cm2 ). LVOT was rather elliptical than round, with a mean eccentricity index of 1.47 (ratio of maximum to minimum LVOT diameters) assessed by MDCT. Mean TTE AVA estimated by the CE was 0.62±0.20 cm2 . Substitution of 2DTTE LVOT area by 3DTEE LVOT area in the CE resulted in AVA of 0.74±0.24 cm2 , while using MDCT LVOT area held an AVA of 0.80±0.24 cm2 . MDCT-derived AVA was similar to MDCT planimetric AVA and allowed 24% of patients to be reclassified from severe to moderate AS. CONCLUSIONS: 2DTTE and 3DTEE underestimate LVOT area when compared to MDCT with significant impact on AVA estimation. Assessment through MDCT fusion AVA may be of incremental value in patients with discrepant severity criteria for AS.