A Common Symptom With an Uncommon Diagnosis: A Case of Primary Esophageal Diffuse Large B-cell Lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma. Although it can have gastrointestinal involvement, there are limited recorded cases that show primary esophageal DLBCL. This report discusses the case of an 85-year-old female who initially presented with weight loss associated with dysphagia and was later diagnosed with an esophageal mass by endoscopy. Pathology showed large, atypical lymphocytes, and the final morphologic, immunohistochemical, and molecular findings were most consistent with a diagnosis of primary esophageal DLBCL.

Enantioselectivity in the enzymatic dehydration of malate and tartrate: Mirror image specificities of structurally similar dehydratases.

Malate (2-hydroxysuccinic acid) and tartrate (2,3-dihydroxysuccinic acid) are chiral substrates; the former existing in two enantiomeric forms (R and S) while the latter exists as three stereoisomers (R,R; S,S; and R,S). Dehydration by stereospecific hydrogen abstraction and antielimination of the hydroxyl group yield the achiral products fumarate and oxaloacetate, respectively. Class-I fumarate hydratase (FH) and L-tartrate dehydratase (L-TTD) are two highly conserved enzymes belonging to the iron-sulfur cluster hydrolyase family of enzymes that catalyze reactions on specific stereoisomers of malate and tartrate. FH from Methanocaldococcus jannaschii accepts only (S)-malate and (S,S)-tartrate as substrates while the structurally similar L-TTD from Escherichia coli accepts only (R)-malate and (R,R)-tartrate as substrates. Phylogenetic analysis reveals a common evolutionary origin of L-TTDs and two-subunit archaeal FHs suggesting a divergence during evolution that may have led to the switch in substrate stereospecificity preference. Due to the high conservation of their sequences, a molecular basis for switch in stereospecificity is not evident from analysis of crystal structures of FH and predicted structure of L-TTD. The switch in enantiomer preference may be rationalized by invoking conformational plasticity of the amino acids interacting with the substrate, together with substrate reorientation and conformer selection about the C2C3 bond of the dicarboxylic acid substrates. Although classical models of enzyme-substrate binding are insufficient to explain such a phenomenon, the enantiomer superposition model suggests that a minor reorientation in the active site residues could lead to the switch in substrate stereospecificity.

Revisiting the Burden Borne by Fumarase: Enzymatic Hydration of an Olefin.

Fumarate hydratase (FH) is a remarkable catalyst that decreases the free energy of the catalyzed reaction by 30 kcal mol-1, much larger than most exceptional enzymes with extraordinary catalytic rates. Two classes of FH are observed in nature: class-I and class-II, which have different folds, yet catalyze the same reversible hydration/dehydration reaction of the dicarboxylic acids fumarate/malate, with equal efficiencies. Using class-I FH from the hyperthermophilic archaeon Methanocaldococcus jannaschii (Mj) as a model along with comparative analysis with the only other available class-I FH structure from Leishmania major (Lm), we provide insights into the molecular mechanism of catalysis in this class of enzymes. The structure of MjFH apo-protein has been determined, revealing that large intersubunit rearrangements occur across apo- and holo-protein forms, with a largely preorganized active site for substrate binding. Site-directed mutagenesis of active site residues, kinetic analysis, and computational studies, including density functional theory (DFT) and natural population analysis, together show that residues interacting with the carboxylate group of the substrate play a pivotal role in catalysis. Our study establishes that an electrostatic network at the active site of class-I FH polarizes the substrate fumarate through interactions with its carboxylate groups, thereby permitting an easier addition of a water molecule across the olefinic bond. We propose a mechanism of catalysis in FH that occurs through transition-state stabilization involving the distortion of the electronic structure of the substrate olefinic bond mediated by the charge polarization of the bound substrate at the enzyme active site.

Creating a Chest Wall Injury and Reconstructive program: A single center experience with rib fractures.

BACKGROUND: New Chest Wall Injury and Reconstructive Centers (CWIRC) are emerging; this study aims to investigate the potential benefits of implementing a CWIRC at a single institution. We hypothesized that patients treated at CWIRC will have improved outcomes. METHODS: We instituted a CWIRC in 2019 at our American College of Surgeons (ACS) Level One Trauma Center. We retrospectively compared trauma patients with rib fractures who presented to our center 18 months before (PRE-C) and 18 months after CWIRC implementation (POST-C). Outcomes measured included mortality, length of stay (LOS), intensive care unit (ICU-LOS), readmission rates, and unplanned ICU admission. RESULTS: There were 192 PRE-C patients, compared to 388 POST-C. The mortality in PRE-C was not significantly different compared to the POST-C group (11.46% vs 8.8%, p=0.308). There were also no differences in LOS, ICU-LOS, readmission, and unplanned ICU admission. ICU utilization was dramatically different: PRE-C 17.8% were admitted to ICU compared to 35.6% POST-C (p<0.0001). CONCLUSIONS: The number of patients admitted with rib fractures to our center nearly doubled after CWIRC establishment. Early diagnosis and triage led to significantly more admissions to higher levels of care. There are trends toward improved outcomes using practice management protocols, albeit with higher ICU utilization. Establishment of a CWIRC should be considered for level 1 ACS trauma centers and as utilization of established CWIRC protocols are increased, patients will have improved outcomes. LEVEL OF EVIDENCE: IV STUDY TYPE: Retrospective chart review.

Thidiazuron, a phenyl-urea cytokinin, inhibits ergosterol synthesis and attenuates biofilm formation of Candida albicans.

Candida albicans is a common human fungal pathogen that colonizes mucosa and develops biofilm in the oral cavity that causes oral candidiasis. It has been reported that cytochrome P450 enzyme (CYP51), a vital part of the ergosterol synthesis cascade, is associated with Candida infections and its biofilm formation. Thidiazuron, a phenyl-urea cytokinin, exhibits anti-senescence and elicitor activity against fungal infection in plants. However, how Thidiazuron impacts C. albicans biofilm formation is still uncertain. Here, we aimed to investigate the effects of a Thidiazuron against the growth and biofilm formation properties of C. albicans using in silico and in vitro experimental approaches. A preliminary molecular docking study revealed potential interaction between Thidiazuron and amino acid residues of CYP51. Further in vitro antifungal susceptibility test, scanning electron microscopy (SEM) and time kill analysis revealed the anti-fungal activity of Thidiazuron in both dose and time-dependent manner. Crystal violet staining, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay revealed 50% inhibition in C. albicans biofilm by Thidiazuron at concentrations 11 and 19 µM respectively. Acridine orange staining assay visually confirmed the biofilm inhibitory potential of Thidiazuron. The gene expression study showed that Thidiazuron treatment down regulated the expression of genes involved in ergosterol synthesis (ERG3, ERG11, ERG25), cell adhesion (ASL3, EAP1), and hyphae development (EFG1, HWP1, SAP5) in C. albicans. Wherease, the expression of negative transcription regulator of hyphae (NRG1) was upregulated (5.7-fold) by Thidiazuron treatment. Collectively, our data suggest that Thidiazuron is a robust antifungal compound and an outstanding biofilm inhibitor, which may promise further therapeutic development due to CYP51 binding and inhibition of ergosterol formation against C. albicans.

Uniform binding and negative catalysis at the origin of enzymes.

Enzymes are well known for their catalytic abilities, some even reaching "catalytic perfection" in the sense that the reaction they catalyze has reached the physical bound of the diffusion rate. However, our growing understanding of enzyme superfamilies has revealed that only some share a catalytic chemistry while others share a substrate-handle binding motif, for example, for a particular phosphate group. This suggests that some families emerged through a "substrate-handle-binding-first" mechanism ("binding-first" for brevity) instead of "chemistry-first" and we are, therefore, left to wonder what the role of non-catalytic binders might have been during enzyme evolution. In the last of their eight seminal, back-to-back articles from 1976, John Albery and Jeremy Knowles addressed the question of enzyme evolution by arguing that the simplest mode of enzyme evolution is what they defined as "uniform binding" (parallel stabilization of all enzyme-bound states to the same degree). Indeed, we show that a uniform-binding proto-catalyst can accelerate a reaction, but only when catalysis is already present, that is, when the transition state is already stabilized to some degree. Thus, we sought an alternative explanation for the cases where substrate-handle-binding preceded any involvement of a catalyst. We find that evolutionary starting points that exhibit negative catalysis can redirect the reaction's course to a preferred product without need for rate acceleration or product release; that is, if they do not stabilize, or even destabilize, the transition state corresponding to an undesired product. Such a mechanism might explain the emergence of "binding-first" enzyme families like the aldolase superfamily.

The Gastrointestinal Stromal Tumor (GIST) of a Pancreatic Cyst.

Gastrointestinal stromal tumors (GISTs) are rare tumors and rarely occur outside of the gastrointestinal (GI) tract. When GISTs originate from outside the GI tract, they are called extra-gastrointestinal stromal tumors (EGISTs). In this article, we discuss a case of a 74-year-old woman who presented due to a growing pancreatic lesion on imaging and was subsequently diagnosed with pancreatic EGIST on endoscopic ultrasound with fine-needle aspiration.

Mechanisms of protein evolution.

How do proteins evolve? How do changes in sequence mediate changes in protein structure, and in turn in function? This question has multiple angles, ranging from biochemistry and biophysics to evolutionary biology. This review provides a brief integrated view of some key mechanistic aspects of protein evolution. First, we explain how protein evolution is primarily driven by randomly acquired genetic mutations and selection for function, and how these mutations can even give rise to completely new folds. Then, we also comment on how phenotypic protein variability, including promiscuity, transcriptional and translational errors, may also accelerate this process, possibly via "plasticity-first" mechanisms. Finally, we highlight open questions in the field of protein evolution, with respect to the emergence of more sophisticated protein systems such as protein complexes, pathways, and the emergence of pre-LUCA enzymes.

Caecal volvulus in a foramen of Winslow hernia.

Caecal herniation through the foramen of Winslow is an uncommon presentation of internal hernia with an estimated overall incidence of 0.02%. Even rarer still is a caecal volvulus strangulated in the lesser sac, a surgical emergency seldom described in the literature. A woman in her 70s presented with a 1-day history of acute-onset right upper quadrant and epigastric pain associated with nausea and vomiting. Prompt CT imaging revealed caecal volvulus within a foramen of Winslow hernia. The diagnosis was confirmed by laparotomy. A right hemicolectomy was performed and the foraminal defect was closed. We identified eight case reports of this rare entity published within the last 30 years. Our patient was managed in a similar manner and recovered without complication, providing further guidance for the operative management of caecal volvulus in the foramen of Winslow.

A counter-enzyme complex regulates glutamate metabolism in Bacillus subtilis.

Multi-enzyme assemblies composed of metabolic enzymes catalyzing sequential reactions are being increasingly studied. Here, we report the discovery of a 1.6 megadalton multi-enzyme complex from Bacillus subtilis composed of two enzymes catalyzing opposite ('counter-enzymes') rather than sequential reactions: glutamate synthase (GltAB) and glutamate dehydrogenase (GudB), which make and break glutamate, respectively. In vivo and in vitro studies show that the primary role of complex formation is to inhibit the activity of GudB. Using cryo-electron microscopy, we elucidated the structure of the complex and the molecular basis of inhibition of GudB by GltAB. The complex exhibits unusual oscillatory progress curves and is necessary for both planktonic growth, in glutamate-limiting conditions, and for biofilm growth, in glutamate-rich media. The regulation of a key metabolic enzyme by complexing with its counter enzyme may thus enable cell growth under fluctuating glutamate concentrations.

Victims of Violence and Post-Discharge Adverse Events: A Prospective Modified Trauma Quality Improvement Program (TQIP) Study.

Introduction Trauma patients frequently return to an emergency department (ED) soon after discharge; often for non-urgent reasons. Social factors contribute to higher ED usage. At present, there is no standardized system for reporting of ED visits and readmissions among trauma care. We hypothesized that victims of violent crime suffer from many early post-discharge adverse events that has not been captured by current methods. Methods We prospectively consented and enrolled injured patients from January 1st, 2019 to December 31st, 2019. We documented 30-day post-discharge events using post-discharge phone calls and detailed chart abstraction. Patients were categorized as victims of violence (VV) or unintentional traumatic injury (UT). Results During the study period, 444 patients were enrolled. Fifty-one (11.5%) were victims of violence and 393 (88.5%) experienced unintentional injuries. The VV patients were younger (40.10 vs 60.36; p<0.0001), and more predominantly male (92.16% vs 57.51%; p<0.0001). Total injury severity score (ISS), critical care length of stay (LOS), and total LOS were similar. VV patients were more likely discharged home (70.59% vs 55.47%; p=0.0403). They were significantly more likely to return to an emergency department (47.06% vs 23.16%; p<0.0005) and had more total number of ED visits per patient. Readmission rates, however, were not different (21.57% vs 16.28%; p=NS). The VV patients more frequently were underinsured (72.5%, vs 20.6%, p<0.005). Discussion Victims of violence presented to the ED significantly more often, despite similar injury scores, LOS, and being of younger age. Of these patients, only 26.2% of ED presentations resulted in readmission, suggesting the majority of patient complaints may have been able to be managed in an office-based setting. VV had significantly more underinsured or subsidized patients. Victims of violence are vulnerable and may benefit from more resources provided in the early post-discharge period.

Fluoroscopy-guided shaped endobiliary biopsy at endoscopic retrograde cholangiography can accurately diagnose biliary neoplasia: Results from a large cohort.

Background and study aims The sensitivity of using standard endobiliary forceps biopsy to diagnose neoplastic biliary lesions remains low. We have developed a unique biopsy approach, termed fluoroscopy-guided, shaped endobiliary biopsy (FSEB), in which the biopsy forceps are modified to improve diagnostic yield. In this study, we evaluate the diagnostic characteristics of FSEB for endobiliary lesions at endoscopic retrograde cholangiography (ERC). Patients and methods Consecutive patients undergoing FSEB between 1/2001 and 12/2014 were retrospectively enrolled. The identification of neoplastic lesions with FSEB, was the primary endpoint. The gold standard of neoplasia was histopathology, cytology or surgical histopathology. The benign cases were followed up for one year. Results A total of 204 patients undergoing 250 biopsy sessions by FSEB were analyzed. Per-patient analysis was performed and FSEB showed 81.1 % sensitivity and 88.2 % accuracy. FSEB detection of proximal biliary lesions was more sensitive (91.1 % vs 73.2 %, P  < 0.01) and accurate (94.9 % vs 82.2 %, P  < 0.01) compared to distal lesions. No complications from FSEB were reported. Conclusions FSEB shows high accuracy for diagnosis of neoplasia in biliary strictures, especially for proximal lesions. Future prospective randomized controlled studies are merited to further validate the role of FSEB as the first-line sampling tool for evaluation of biliary neoplasm.

Biochemical characterization and essentiality of Plasmodium fumarate hydratase.

Plasmodium falciparum (Pf), the causative agent of malaria, has an iron-sulfur cluster-containing class I fumarate hydratase (FH) that catalyzes the interconversion of fumarate to malate, a well-known reaction in the tricarboxylic acid cycle. In humans, the same reaction is catalyzed by class II FH that has no sequence or structural homology with the class I enzyme from Plasmodium Fumarate is generated in large quantities in the parasite as a by-product of AMP synthesis and is converted to malate by FH and then used in the generation of the key metabolites oxaloacetate, aspartate, and pyruvate. Previous studies have identified the FH reaction as being essential to P. falciparum, but biochemical characterization of PfFH that may provide leads for the development of specific inhibitors is lacking. Here, we report on the kinetic characterization of purified recombinant PfFH, functional complementation of fh deficiency in Escherichia coli, and mitochondrial localization in the parasite. We found that the substrate analog mercaptosuccinic acid is a potent PfFH inhibitor, with a Ki value in the nanomolar range. The fh gene could not be knocked out in Plasmodium berghei when transfectants were introduced into BALB/c mice; however, fh knockout was successful when C57BL/6 mice were used as host, suggesting that the essentiality of the fh gene to the parasite was mouse strain-dependent.

Gamified Twitter Microblogging to Support Resident Preparation for the American Board of Surgery In-Service Training Examination.

OBJECTIVE: We sought to determine if a daily gamified microblogging project improves American Board of Surgery In-Service Training Examination (ABSITE) scores for participants. DESIGN: In July 2016, we instituted a gamified microblogging project using Twitter as the platform and modified questions from one of several available question banks. A question of the day was posted at 7-o׳clock each morning, Monday through Friday. Respondents were awarded points for speed, accuracy, and contribution to discussion topics. The moderator challenged respondents by asking additional questions and prompted them to find evidence for their claims to fuel further discussion. Since 4 months into the microblogging program, a survey was administered to all residents. Responses were collected and analyzed. After 6 months of tweeting, residents took the ABSITE examination. We compared participating residents׳ ABSITE percentile rank to those of their nonparticipating peers. We also compared residents׳ percentile rank from 2016 to those in 2017 after their participation in the microblogging project. SETTING: The University of Connecticut general surgery residency is an integrated program that is decentralized across 5 hospitals in the central Connecticut region, including Saint Francis Hospital and Medical Center, located in Hartford. PARTICIPANTS: We advertised our account to the University of Connecticut general surgery residents. Out of 45 residents, 11 participated in Twitter microblogging (24.4%) and 17 responded to the questionnaire (37.8%). RESULTS: In all, 100% of the residents who were participating in Twitter reported that daily microblogging prompted them to engage in academic reading. Twitter participants significantly increased their ABSITE percentile rank from 2016 to 2017 by an average of 13.7% (±14.1%) while nonparticipants on average decreased their ABSITE percentile rank by 10.0% (±16.6) (p = 0.003). CONCLUSIONS: Microblogging via Twitter with gamification is a feasible strategy to facilitate improving performance on the ABSITE, especially in a geographically distributed residency.

1.6 kW Yb fiber amplifier using chirped seed amplification for stimulated Brillouin scattering suppression.

In a high power fiber amplifier, a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS). Moving the external mirror of a vertical cavity surface-emitting diode laser 0.2 µm in 10 µs can yield a frequency chirp of 5×1017 Hz/s at a nearly constant output power. Opto-electronic feedback loops can linearize the chirp, and stabilize the output power. The linear variation of phase with time allows multiple amplifiers to be coherently combined using a frequency shifter to compensate for static and dynamic path length differences. The seed bandwidth, as seen by the counter-propagating SBS, also increases linearly with fiber length, resulting in a nearly-length-independent SBS threshold. Experimental results at the 1.6 kW level with a 19 m delivery fiber are presented. A numerical simulation is also presented.

Direct oral anticoagulants compared with warfarin in patients with severe blunt trauma.

METHODS: We queried our Trauma Quality Improvement Program registry for patients who presented between 6/1/2011 and 9/1/2015 with severe (injury severity score (ISS)>15) blunt traumatic injury during anticoagulant use. Patients were then grouped into those prescribed warfarin and patients prescribed any of the available novel Direct Oral Anticoagulants (DOAC) medications. We excluded severe (AIS≧4) head injuries. RESULTS: There were no differences between DOAC and warfarin groups in terms of age, gender mean ISS, median hospital or intensive care unit lengths of stay, complication proportions, numbers of complications per patient, or the proportion of patients requiring transfusion. Finally, excluding patients who died, the observed proportion of discharge to skilled nursing facility was similar. In our sample of trauma patients, DOAC use was associated with significantly lower mortality (DOAC group 8.3% vs. warfarin group 29.5%, p<0.015). The ratio of units transfused per patient was also lower in the DOAC group (2.8±1.8 units/patient in the DOAC group vs. 6.7±6.4 units per patient in the warfarin group; p=0.001). CONCLUSION: In conclusion, we report an association with decrease in mortality and a decrease in transfused blood products in severely injured trauma patients with likely minimal or no head injury taking novel DOACs over those anticoagulated with warfarin for outpatient anticoagulation.

Immediate Tube Feeding after Percutaneous Endoscopic Gastrostomy: Early Return to Goal Tube Feeds without Added Complications.

BACKGROUND: Percutaneous endoscopic gastrostomy (PEG) is frequently performed for delivery of nonoral enteral nutrition (EN) in critically ill patients. Tube-based supplement initiation is often delayed for a variety of reasons despite evidence that EN interruption results in worse outcomes. OBJECTIVE: To determine if early initiation of EN after PEG placement is safe and well-tolerated in critically ill patients and if early initiation of EN results in more goal-accomplished days of EN. DESIGN: A retrospective chart review of patients who underwent PEG and at least 24 hours of EN. Patients were stratified according to time to tube- feed initiation: immediate (< one hour), early (one to four hours), and late (four to 24 hours). RESULTS: 'Ihe three groups were similar with respect to demographics, comorbidities, and 30-day mortality. Sixty-one percent of patients in the immediate group were advanced to the previously-met goal EN rates compared to 24% and 18% in the early and delayed groups, respectively (P < .0001). CONCLUSION: Immediate reinitiation of nonoral EN after PEG procedure is safe and is associated with reaching goal nutrition faster.

Compared to warfarin, direct oral anticoagulants are associated with lower mortality in patients with blunt traumatic intracranial hemorrhage: A TQIP study.

BACKGROUND: Falls represent the leading cause of traumatic brain injury in adults older than 65, with nearly one third experiencing a fall each year. Evidence suggests that up to 0.5% of anticoagulated patients suffer from intracranial hemorrhage (ICH) annually. Direct oral anticoagulants (DOACs) have become an increasingly popular alternative to warfarin for anticoagulation; however, there is a dearth of research regarding the safety of DOACs, in particular on the outcome of traumatic ICH while taking DOACs. METHODS: We queried our Trauma Quality Improvement Project registry for patients who presented with traumatic intracranial hemorrhage during anticoagulant use. Patients were grouped into those prescribed warfarin and patients prescribed DOAC medications. The groups were compared with respect to age, gender, Glasgow Coma Score (GCS) on arrival, Abbreviated Injury Scale (AIS) (head), Injury Severity Score (ISS), mortality, need for operative intervention, hospital and ICU lengths of stay, proportion of patients transfused (and their transfusion requirements), and rates of discharge to skilled nursing facility. Poisson regression was conducted to determine the relationship between mortality and treatment group while controlling for covariates (comorbidities, ISS). RESULTS: There were no differences between DOAC and warfarin groups in terms of age, gender, median ISS, median AIS head, or median admission GCS. Mechanisms of injury, median hospital and ICU lengths of stay, ICU free days, and transfusion requirements were also not significantly different.DOAC use was associated with significantly lower mortality (4.9% vs. 20.8%; p < 0.008) and a lower rate of operative intervention (8.2% vs. 26.7%; p = 0.023) when compared with warfarin. Excluding patients who died, the observed rate of discharge to skilled nursing facility was lower in the DOAC group (28.8% compared with 39.7%; p = 0.03). Multivariate Poisson regression analysis demonstrated that warfarin use was associated with an increased mortality when controlling for injury severity, and comorbidities. CONCLUSIONS: We report improved mortality and reduced rates of operative intervention in patients with traumatic ICH associated with DOACs compared with a similar group taking warfarin. We also noted an association with decreased rate of discharge to SNF in patients taking DOACs compared with warfarin. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Cost Savings Associated with the Adoption of a Cloud Computing Data Transfer System for Trauma Patients.

INTRODUCTION: Among transferred trauma patients, challenges with the transfer of radiographic studies include problems loading or viewing the studies at the receiving hospitals, and problems manipulating, reconstructing, or evalu- ating the transferred images. Cloud-based image transfer systems may address some ofthese problems. METHODS: We reviewed the charts of patients trans- ferred during one year surrounding the adoption of a cloud computing data transfer system. We compared the rates of repeat imaging before (precloud) and af- ter (postcloud) the adoption of the cloud-based data transfer system. RESULTS: During the precloud period, 28 out of 100 patients required 90 repeat studies. With the cloud computing transfer system in place, three out of 134 patients required seven repeat films. CONCLUSION: There was a statistically significant decrease in the proportion of patients requiring repeat films (28% to 2.2%, P < .0001). Based on an annualized volume of 200 trauma patient transfers, the cost savings estimated using three methods of cost analysis, is between $30,272 and $192,453.