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INTRODUCTION:Dieulafoy lesions involve a large-caliber, tortuous artery in the muscularis mucosa that protrudes due to a submucosal defect with fibrinoid necrosis at the base. The submucosal artery is found to have atypical branching and as a result has a diameter of 1-3 mm, which is 10 times that of a normal mucosal capillary. These lesions can be found throughout the gastrointestinal tract, though they are most frequently found in the stomach, ranging between 61 to 82%. However 10% of all gastrointestinal tract Dieulafoy lesions are found in the colon with 42% of these lesions found in the rectum.CASE DESCRIPTION/METHODS:A 79-year-old male with past medical history significant for prostate cancer, hypertension, gout, degenerative joint disease and alcohol abuse disorder presented with bilateral leg weakness and was admitted to the medical service for alcohol dependency and acute kidney injury. On day 12 of hospitalization, he developed melena with a drop in hemoglobin from 12.0 g/dL at the time of admission to 7.7 g/dL. He was then transferred to the critical care unit and underwent esophagogastroduodenoscopy that revealed angioectatic lesions that bled and were treated with argon photocoagulation. On day 15, he developed hematochezia, which further decreased his hemoglobin to 6.9 g/dL. He became hemodynamically unstable, requiring rapid fluid and blood resuscitation. Emergent CT angiography was concerning for vascular malformation in the rectal wall. Colonoscopy was performed and a stream of pulsatile bleeding without an ulcer or varix, consistent with a Dieulafoy lesion, was seen in the rectum. Epinephrine was applied, the lesion was clipped, and hemostasis was achieved. No repeat episodes of gastrointestinal bleeding were reported afterwards.DISCUSSION:Bleeding from Dieulafoy lesions can cause hemodynamic compromise as noted in this patient. Therefore prompt identification and treatment is warranted. Endoscopy serves as a gold standard for identification. Hemostasis has been achieved with many techniques in case reports including: BICAP cauterization; combined sclerotherapy and electrocoagulation; heater-probe coagulation; and epinephrine injection combined with electrocoagulation. Rebleeding rate ranges from 6 to 28%. Systemic reviews and retrospective analysis suggest that mechanical ligation to achieve hemostasis, especially the use of hemoclips, may be superior to other techniques employed.

To investigate the predictability of genetic adaptation, we examined the molecular basis of convergence in hemoglobin function in comparisons involving 56 avian taxa that have contrasting altitudinal range limits. Convergent increases in hemoglobin-oxygen affinity were pervasive among high-altitude taxa, but few such changes were attributable to parallel amino acid substitutions at key residues. Thus, predictable changes in biochemical phenotype do not have a predictable molecular basis. Experiments involving resurrected ancestral proteins revealed that historical substitutions have context-dependent effects, indicating that possible adaptive solutions are contingent on prior history. Mutations that produce an adaptive change in one species may represent precluded possibilities in other species because of differences in genetic background.

The malaria parasite mines actin from the membrane skeleton of its erythrocyte host to generate a cytoskeletal structure. The hemoglobins S and C protect carriers from severe Plasmodium falciparum malaria. Here, we found that these hemoglobinopathies affected the trafficking system that directs parasite-encoded proteins to the surface of infected erythrocytes. Cryoelectron tomography revealed that the parasite generated a host-derived actin cytoskeleton within the cytoplasm of wild-type red blood cells that connected the Maurer’s clefts with the host cell membrane and to which transport vesicles were attached. The actin cytoskeleton and the Maurer’s clefts were aberrant in erythrocytes containing hemoglobin S or C. Hemoglobin oxidation products, enriched in hemoglobin S and C erythrocytes, inhibited actin polymerization in vitro and may account for the protective role in malaria.

Introduction: Blood transfusions continue to be a critical intervention in patients presenting to emergency departments (ED). Improved understanding of the adverse events associated with transfusions has led to new research to inform and delineate transfusion guidelines. The Nova Scotia Guideline for Blood Component Utilization in Adults and Pediatrics was implemented in June 2017 to reflect current best practice in transfusion medicine. The guideline includes a lowering of the hemoglobin threshold from 80 g/L to 70 g/L for transfusion initiation, to be used in conjunction with the patient's hemodynamic assessment before and after transfusions. Our study aims to augment understanding of transfusion guideline adherence and ED physician transfusing practices at the Halifax Infirmary Emergency Department in Nova Scotia. Methods: A retrospective chart review was conducted on one third of all ED visits involving red-cell transfusions for one year prior to and one year following the guideline implementation. A total of 350 charts were reviewed. The primary data abstracted for the initial transfusion, and subsequent transfusion if applicable, from each reviewed chart included clinical and laboratory data reflective of the transfusion guideline. Based on these data, the transfusion event was classified one of three ways: indicated based on hemoglobin level, indicated based on patient's symptomatic presentation, or unable to determine if transfusion indicated based on charting. Results: The year before guideline implementation, the total number of transfusions initiated at a hemoglobin of between 71-80 was 31 of 146 total transfusions. This number dropped by 23.6% to 22 of 136 in the year following guideline implementation. The number of single-unit transfusions increased by 28.0% from 47 of 146 in the year prior to 56 of 136 in the year after guideline implementation. The initial indication for transfusion being unable to be determined based on charting provided increased by 120%. The indication for subsequent transfusions being unable to be determined based on charting increased by 1500% (P < 0.05). Conclusion: These data suggest that implementing transfusion guidelines effectively reduced the number of transfusions given in the ED setting and increased the number of single-unit transfusions administered. However, the data also suggest the need for better education around transfusion indications and proper documentation clearly outlining the rationale behind the decision to transfuse.