Clinical outcomes of nonvariceal upper gastrointestinal bleeding in nonagenarians and octogenarians: a comparative nationwide analysis.

BACKGROUND/AIMS: Nonagenarians will purportedly account for 10% of the United States population by 2050. However, no studies have assessed the outcomes of nonvariceal upper gastrointestinal bleeding (NVUGIB) in this age group. METHODS: The National Inpatient Sample database between 2016 and 2020 was used to compare the clinical outcomes of NVUGIB in nonagenarians and octogenarians and evaluate predictors of mortality and the use of esophagogastroduodenoscopy (EGD). RESULTS: Nonagenarians had higher in-hospital mortality than that of octogenarians (4% vs. 3%, p<0.001). EGD utilization (30% vs. 48%, p<0.001) and blood transfusion (27% vs. 40%, p<0.001) was significantly lower in nonagenarians. Multivariate logistic regression analysis revealed that nonagenarians with NVUGIB had higher odds of mortality (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.3-1.7) and lower odds of EGD utilization (OR, 0.86; 95% CI, 0.83-0.89) than those of octogenarians. CONCLUSIONS: Nonagenarians admitted with NVUGIB have a higher mortality risk than that of octogenarians. EGD is used significantly in managing NVUGIB among nonagenarians; however, its utilization is comparatively lower than in octogenarians. More studies are needed to assess predictors of poor outcomes and the indications of EGD in this growing population.

Primary Gastrointestinal T-cell Lymphoma Presenting as Spontaneous Perforation Peritonitis.

Primary T-cell non-Hodgkin lymphoma (NHL) of the gastrointestinal tract (GIT) is a rare, poorly-characterized clinical entity. A well-known complication of intestinal NHL is perforation due to chemotherapy, but perforation as a presenting sign of GIT lymphoma is extremely rare. Here we present a case of spontaneous intestinal perforation secondary to primary intestinal T-cell lymphoma and highlight the importance of early recognition of this uncommon cause of perforation as a crucial step to ensure expedited hematology referral and initiation of appropriate treatment.

Spontaneous Pneumothorax as a Late Complication of Mild COVID-19 Infection: A Case Report.

Spontaneous pneumothorax (PTX) is a rare but life-threatening complication of lung injuries sustained from severe COVID-19 infection, most commonly associated with mechanical ventilation. Development of spontaneous PTX in patients after only mild COVID-19 infections not requiring hospitalization is even rarer. Here, we present the case of a 37-year-old male with spontaneous PTX secondary to a mild COVID-19 infection diagnosed one-month prior. A computed tomography (CT) scan of the chest revealed new air-filled cysts thought to be mediated by the inflammatory response to his acute infection, and his PTX was thought to be secondary to cyst wall rupture due to prolonged coughing. He was successfully treated with a chest tube and supplemental oxygen and, at a two-month follow-up, demonstrated clinical and radiographic improvement.

Diagnosis and Management of Lemmel Syndrome: An Unusual Presentation and Literature Review.

Lemmel syndrome is a rare clinical entity characterized by the presence of a periampullary duodenal diverticulum resulting in compression and dilatation of the pancreatic and common bile ducts, accompanied by obstructive jaundice. Gastric outlet obstruction is not a known complication of this syndrome, and there are no standardized approaches to its treatment. We present the first case of Lemmel syndrome presenting as gastric outlet obstruction and provide the results of a systematic literature review.

The structural basis of fatty acid elongation by the ELOVL elongases.

Very long chain fatty acids (VLCFAs) are essential building blocks for the synthesis of ceramides and sphingolipids. The first step in the fatty acid elongation cycle is catalyzed by the 3-keto acyl-coenzyme A (CoA) synthases (in mammals, ELOVL elongases). Although ELOVLs are implicated in common diseases, including insulin resistance, hepatic steatosis and Parkinson's, their underlying molecular mechanisms are unknown. Here we report the structure of the human ELOVL7 elongase, which comprises an inverted transmembrane barrel surrounding a 35-Å long tunnel containing a covalently attached product analogue. The structure reveals the substrate-binding sites in the narrow tunnel and an active site deep in the membrane. We demonstrate that chain elongation proceeds via an acyl-enzyme intermediate involving the second histidine in the canonical HxxHH motif. The unusual substrate-binding arrangement and chemistry suggest mechanisms for selective ELOVL inhibition, relevant for diseases where VLCFAs accumulate, such as X-linked adrenoleukodystrophy.

Mechanistic dissection of the PD-L1:B7-1 co-inhibitory immune complex.

The B7 family represents one of the best-studied subgroups within the Ig superfamily, yet new interactions continue to be discovered. However, this binding promiscuity represents a major challenge for defining the biological contribution of each specific interaction. We developed a strategy for addressing these challenges by combining cell microarray and high-throughput FACS methods to screen for promiscuous binding events, map binding interfaces, and generate functionally selective reagents. Applying this approach to the interactions of mPD-L1 with its receptor mPD-1 and its ligand mB7-1, we identified the binding interface of mB7-1 on mPD-L1 and as a result generated mPD-L1 mutants with binding selectivity for mB7-1 or mPD-1. Next, using a panel of mB7-1 mutants, we mapped the binding sites of mCTLA-4, mCD28 and mPD-L1. Surprisingly, the mPD-L1 binding site mapped to the dimer interface surface of mB7-1, placing it distal from the CTLA-4/CD28 recognition surface. Using two independent approaches, we demonstrated that mPD-L1 and mB7-1 bind in cis, consistent with recent reports from Chaudhri A et al. and Sugiura D et al. We further provide evidence that while CTLA-4 and CD28 do not directly compete with PD-L1 for binding to B7-1, they can disrupt the cis PD-L1:B7-1 complex by reorganizing B7-1 on the cell surface. These observations offer new functional insights into the regulatory mechanisms associated with this group of B7 family proteins and provide new tools to elucidate their function in vitro and in vivo.

Author Correction: A naturally occurring antiviral ribonucleotide encoded by the human genome.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The structural basis of lipid scrambling and inactivation in the endoplasmic reticulum scramblase TMEM16K.

Membranes in cells have defined distributions of lipids in each leaflet, controlled by lipid scramblases and flip/floppases. However, for some intracellular membranes such as the endoplasmic reticulum (ER) the scramblases have not been identified. Members of the TMEM16 family have either lipid scramblase or chloride channel activity. Although TMEM16K is widely distributed and associated with the neurological disorder autosomal recessive spinocerebellar ataxia type 10 (SCAR10), its location in cells, function and structure are largely uncharacterised. Here we show that TMEM16K is an ER-resident lipid scramblase with a requirement for short chain lipids and calcium for robust activity. Crystal structures of TMEM16K show a scramblase fold, with an open lipid transporting groove. Additional cryo-EM structures reveal extensive conformational changes from the cytoplasmic to the ER side of the membrane, giving a state with a closed lipid permeation pathway. Molecular dynamics simulations showed that the open-groove conformation is necessary for scramblase activity.

Lentiviral Gene Therapy Combined with Low-Dose Busulfan in Infants with SCID-X1.

BACKGROUND: Allogeneic hematopoietic stem-cell transplantation for X-linked severe combined immunodeficiency (SCID-X1) often fails to reconstitute immunity associated with T cells, B cells, and natural killer (NK) cells when matched sibling donors are unavailable unless high-dose chemotherapy is given. In previous studies, autologous gene therapy with γ-retroviral vectors failed to reconstitute B-cell and NK-cell immunity and was complicated by vector-related leukemia. METHODS: We performed a dual-center, phase 1-2 safety and efficacy study of a lentiviral vector to transfer IL2RG complementary DNA to bone marrow stem cells after low-exposure, targeted busulfan conditioning in eight infants with newly diagnosed SCID-X1. RESULTS: Eight infants with SCID-X1 were followed for a median of 16.4 months. Bone marrow harvest, busulfan conditioning, and cell infusion had no unexpected side effects. In seven infants, the numbers of CD3+, CD4+, and naive CD4+ T cells and NK cells normalized by 3 to 4 months after infusion and were accompanied by vector marking in T cells, B cells, NK cells, myeloid cells, and bone marrow progenitors. The eighth infant had an insufficient T-cell count initially, but T cells developed in this infant after a boost of gene-corrected cells without busulfan conditioning. Previous infections cleared in all infants, and all continued to grow normally. IgM levels normalized in seven of the eight infants, of whom four discontinued intravenous immune globulin supplementation; three of these four infants had a response to vaccines. Vector insertion-site analysis was performed in seven infants and showed polyclonal patterns without clonal dominance in all seven. CONCLUSIONS: Lentiviral vector gene therapy combined with low-exposure, targeted busulfan conditioning in infants with newly diagnosed SCID-X1 had low-grade acute toxic effects and resulted in multilineage engraftment of transduced cells, reconstitution of functional T cells and B cells, and normalization of NK-cell counts during a median follow-up of 16 months. (Funded by the American Lebanese Syrian Associated Charities and others; LVXSCID-ND ClinicalTrials.gov number, NCT01512888.).

Labeling Changes and Costs for Clinical Trials Performed Under the US Food and Drug Administration Pediatric Exclusivity Extension, 2007 to 2012.

Importance: Pharmaceutical manufacturers can receive 6 additional months of market exclusivity for performing pediatric clinical trials of brand-name drugs widely used in adults. Congress created this incentive in 1997 because these drugs were being used off-label in children without such trials. Objective: To review updates to drug labeling and the cost to consumers of extending market exclusivity related to the pediatric exclusivity program. Design: From government records, we identified 54 drugs that earned the pediatric exclusivity incentive between 2007 and 2012. We evaluated labeling changes from the pediatric studies. We then extracted trial details from clinical review documents and used industry estimates of trial costs on a per-patient basis to estimate cost of investment for trials (with a 10% cost of capital). To calculate the net return and cost to consumers during the 6-month exclusivity period, we estimated additional revenue for the 48 drugs with available information. Main Outcomes and Measures: For each drug, we evaluated labeling changes and costs associated with pediatric trials under the Best Pharmaceuticals for Children Act and the cost to consumers of 6-month market exclusivity extensions. Results: The 141 trials in our sample enrolled 20 240 children (interquartile range [IQR], 2-3 trials and 127-556 patients per drug). These trials led to 29 extended indications and 3 new indications, as well as new safety information for 16 drugs. Median cost of investment for trials was $36.4 million (IQR, $16.6 to $100.6 million). Among 48 drugs with available financial information, median net return was $176.0 million (IQR, $47.0 million to $404.1 million), with a median ratio of net return to cost of investment of 680% (IQR, 80% to 1270%). Conclusions and Relevance: Clinical trials conducted under the US Food and Drug Administration's pediatric exclusivity program have provided important information about the effectiveness and safety of drugs used in children. The costs to consumers have been high, exceeding the estimated costs of investment for conducting the trials. As an alternative, policymakers should consider direct funding of such studies.

Publisher Correction: A naturally occurring antiviral ribonucleotide encoded by the human genome.

Change history: In the HTML version of this Letter, Extended Data Fig. 4 incorrectly corresponded to Fig. 4 (the PDF version of the figure was correct). This has been corrected online.

A naturally occurring antiviral ribonucleotide encoded by the human genome.

Viral infections continue to represent major challenges to public health, and an enhanced mechanistic understanding of the processes that contribute to viral life cycles is necessary for the development of new therapeutic strategies 1 . Viperin, a member of the radical S-adenosyl-L-methionine (SAM) superfamily of enzymes, is an interferon-inducible protein implicated in the inhibition of replication of a broad range of RNA and DNA viruses, including dengue virus, West Nile virus, hepatitis C virus, influenza A virus, rabies virus 2 and HIV3,4. Viperin has been suggested to elicit these broad antiviral activities through interactions with a large number of functionally unrelated host and viral proteins3,4. Here we demonstrate that viperin catalyses the conversion of cytidine triphosphate (CTP) to 3'-deoxy-3',4'-didehydro-CTP (ddhCTP), a previously undescribed biologically relevant molecule, via a SAM-dependent radical mechanism. We show that mammalian cells expressing viperin and macrophages stimulated with IFNα produce substantial quantities of ddhCTP. We also establish that ddhCTP acts as a chain terminator for the RNA-dependent RNA polymerases from multiple members of the Flavivirus genus, and show that ddhCTP directly inhibits replication of Zika virus in vivo. These findings suggest a partially unifying mechanism for the broad antiviral effects of viperin that is based on the intrinsic enzymatic properties of the protein and involves the generation of a naturally occurring replication-chain terminator encoded by mammalian genomes.

Structure-based analysis of CysZ-mediated cellular uptake of sulfate.

Sulfur, most abundantly found in the environment as sulfate (SO42-), is an essential element in metabolites required by all living cells, including amino acids, co-factors and vitamins. However, current understanding of the cellular delivery of SO42- at the molecular level is limited. CysZ has been described as a SO42- permease, but its sequence family is without known structural precedent. Based on crystallographic structure information, SO42- binding and flux experiments, we provide insight into the molecular mechanism of CysZ-mediated translocation of SO42- across membranes. CysZ structures from three different bacterial species display a hitherto unknown fold and have subunits organized with inverted transmembrane topology. CysZ from Pseudomonas denitrificans assembles as a trimer of antiparallel dimers and the CysZ structures from two other species recapitulate dimers from this assembly. Mutational studies highlight the functional relevance of conserved CysZ residues.

Systematic Assessment of Research on Autism Spectrum Disorder (ASD) and Mercury Reveals Conflicts of Interest and the Need for Transparency in Autism Research.

Historically, entities with a vested interest in a product that critics have suggested is harmful have consistently used research to back their claims that the product is safe. Prominent examples are: tobacco, lead, bisphenol A, and atrazine. Research literature indicates that about 80-90% of studies with industry affiliation found no harm from the product, while only about 10-20% of studies without industry affiliation found no harm. In parallel to other historical debates, recent studies examining a possible relationship between mercury (Hg) exposure and autism spectrum disorder (ASD) show a similar dichotomy. Studies sponsored and supported by industry or entities with an apparent conflict of interest have most often shown no evidence of harm or no "consistent" evidence of harm, while studies without such affiliations report positive evidence of a Hg/autism association. The potentially causal relationship between Hg exposure and ASD differs from other toxic products since there is a broad coalition of entities for whom a conflict of interest arises. These include influential governmental public health entities, the pharmaceutical industry, and even the coal burning industry. This review includes a systematic literature search of original studies on the potential relationship between Hg and ASD from 1999 to August 2015, finding that of the studies with public health and/or industry affiliation, 86% reported no relationship between Hg and ASD. However, among studies without public health and/or industry affiliation, only 21% find no relationship between Hg and ASD. The discrepancy in these results suggests a bias indicative of a conflict of interest.

Expression of Prokaryotic Integral Membrane Proteins in E. coli.

Production of prokaryotic membrane proteins for structural and functional studies in E. coli can be parallelized and miniaturized. All stages from cloning, expression, purification to detergent selection can be investigated using high-throughput techniques to rapidly and economically find tractable targets.

mTOR regulates peripheral nerve response to tensile strain.

While excessive tensile strain can be detrimental to nerve function, strain can be a positive regulator of neuronal outgrowth. We used an in vivo rat model of sciatic nerve strain to investigate signaling mechanisms underlying peripheral nerve response to deformation. Nerves were deformed by 11% and did not demonstrate deficits in compound action potential latency or amplitude during or after 6 h of strain. As revealed by Western blotting, application of strain resulted in significant upregulation of mammalian target of rapamycin (mTOR) and S6 signaling in nerves, increased myelin basic protein (MBP) and ß-actin levels, and increased phosphorylation of neurofilament subunit H (NF-H) compared with unstrained (sham) contralateral nerves (P < 0.05 for all comparisons, paired two-tailed t-test). Strain did not alter neuron-specific ß3-tubulin or overall nerve tubulin levels compared with unstrained controls. Systemic rapamycin treatment, thought to selectively target mTOR complex 1 (mTORC1), suppressed mTOR/S6 signaling, reduced levels of MBP and overall tubulin, and decreased NF-H phosphorylation in nerves strained for 6 h, revealing a role for mTOR in increasing MBP expression and NF-H phosphorylation, and maintaining tubulin levels. Consistent with stretch-induced increases in MBP, immunolabeling revealed increased S6 signaling in Schwann cells of stretched nerves compared with unstretched nerves. In addition, application of strain to cultured adult dorsal root ganglion neurons showed an increase in axonal protein synthesis based on a puromycin incorporation assay, suggesting that neuronal translational pathways also respond to strain. This work has important implications for understanding mechanisms underlying nerve response to strain during development and regeneration.NEW & NOTEWORTHY Peripheral nerves experience tensile strain (stretch) during development and movement. Excessive strain impairs neuronal function, but moderate strains are accommodated by nerves and can promote neuronal growth; mechanisms underlying these phenomena are not well understood. We demonstrated that levels of several structural proteins increase following physiological levels of nerve strain and that expression of a subset of these proteins is regulated by mTOR. Our work has important implications for understanding nerve development and strain-based regenerative strategies.

Inhibition of Zinc-Dependent Histone Deacetylases with a Chemically Triggered Electrophile.

Unbiased binding assays involving small-molecule microarrays were used to identify compounds that display unique patterns of selectivity among members of the zinc-dependent histone deacetylase family of enzymes. A novel, hydroxyquinoline-containing compound, BRD4354, was shown to preferentially inhibit activity of HDAC5 and HDAC9 in vitro. Inhibition of deacetylase activity appears to be time-dependent and reversible. Mechanistic studies suggest that the compound undergoes zinc-catalyzed decomposition to an ortho-quinone methide, which covalently modifies nucleophilic cysteines within the proteins. The covalent nature of the compound-enzyme interaction has been demonstrated in experiments with biotinylated probe compound and with electrospray ionization-mass spectrometry.

Thumb Metacarpal Subsidence After Partial Trapeziectomy With Capsular Interposition Arthroplasty: A Biomechanical Study.

Background: In a cadaveric model, we evaluated thumb metacarpal subsidence, indicated by a decreased metacarpal-to-scaphoid distance, after 2 surgical procedures used to treat thumb carpometacarpal (CMC) osteoarthritis (OA): partial trapeziectomy with capsular interposition (PTCI), which involves removal of 2 mm of both the distal trapezium and base of the metacarpal; and total trapeziectomy with capsular interposition (TTCI). Methods: Nine matched pairs of cadaveric hands were randomly assigned to undergo either PTCI or TTCI. Preoperatively, physiologic forces were applied across the thumb CMC joint by loading 6 tendons, simulating lateral pinch. Anteroposterior radiographs were obtained, and the metacarpal-to-scaphoid distance on each image was estimated independently by 3 separate readers using customized software. A hand surgeon then performed the PTCI and TTCI procedures, and the measurements under loading were repeated. The results were assessed for interrater reliability. Mean values for metacarpal-to-scaphoid distance before and after the surgical procedures were compared. Results: Preoperatively, the metacarpal-to-scaphoid distance in the PTCI and TTCI groups was not significantly different. Postoperatively, metacarpal subsidence was significantly less in the PTCI group (17% compared with 34% for TTCI; P = .05). Conclusions: Metacarpal subsidence occurred after both PTCI and TTCI, but significantly less subsidence was observed after PTCI; thus, thumb length was better preserved. Previous research has shown an inverse correlation between maintenance of thumb length and overall Disabilities of the Arm, Shoulder, and Hand (DASH) score. A procedure for treating thumb CMC OA that preserves thumb length and minimizes disruption of stabilizing joint tissue may provide enhanced maintenance of thumb stability and improved patient outcomes.