Delayed management of acute type A aortic dissection with concomitant coronary artery bypass graft.

BACKGROUND: Pre-operative coronary angiography and concomitant, planned coronary artery bypass are infrequently performed with type A aortic dissection repair. We present a case in which pre-operative coronary computed tomography angiography was appropriate, and subsequent dissection repair and concomitant coronary artery bypass were successfully performed. CASE PRESENTATION: The patient is a 58-year-old male with heart failure with preserved ejection fraction, renal insufficiency, hypertension, obesity, and smoking history, who presented with a three-to-four-day history of persistent back pain, worsening exertional dyspnea, and orthopnea, as well as a two-to-three month history of dyspnea, lower extremity edema, and intermittent angina. He was diagnosed with an acute type A aortic dissection and anti-impulse control was initiated. However, repair was delayed in order to allow apixaban to metabolize and decrease the risk of bleeding, as the patient was approximately six days post-dissection, without malperfusion, with a well-controlled blood pressure on anti-impulse therapy, and had received five days of anticoagulation. During this time, coronary computed tomography angiography was performed to assess the need for concomitant revascularization and showed coronary artery disease. Ascending aorta hemiarch replacement with aortic valve resuspension, two-vessel coronary artery bypass grafting, and left atrial appendage clipping were performed successfully. CONCLUSIONS: Pre-operative imaging can be considered in a select group of acute type A aortic dissections that present without malperfusion, and with well-controlled blood pressure on anti-impulse/negative inotropic therapy.

Development of a Scalable and Sublimation-Free Route to MTAD.

The cyclic azodicarbonyl 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) is a versatile and powerful reagent used mainly in cycloaddition chemistry. Though known for more than 50 years, its unsafe preparation, as well as purification by sublimation, hampered its widespread applicability on a larger scale. Herein we report a scalable and safe route to MTAD, which avoids the generation of methyl isocyanate. Moreover, we demonstrate that sublimation can be circumvented by the application of judicious oxidation conditions, followed by simple filtration. Overall, up to 25 g of MTAD was prepared in a single batch from commercial starting materials in three steps, with recrystallization serving as the only purification in the sequence. When employed in dearomative methodologies, the MTAD obtained by this protocol displayed synthetic efficiency equivalent to that of MTAD purified by sublimation.

Evolution of pH buffers and water homeostasis in eukaryotes: homology between humans and Acanthamoeba proteins.

AIM: This study intended to trace the evolution of acid-base buffers and water homeostasis in eukaryotes. Acanthamoeba castellanii  was selected as a model unicellular eukaryote for this purpose. Homologies of proteins involved in pH and water regulatory mechanisms at cellular levels were compared between humans and A. castellanii. MATERIALS & METHODS: Amino acid sequence homology, structural homology, 3D modeling and docking prediction were done to show the extent of similarities between carbonic anhydrase 1 (CA1), aquaporin (AQP), band-3 protein and H+ pump. Experimental assays were done with acetazolamide (AZM), brinzolamide and mannitol to observe their effects on the trophozoites of  A. castellanii. RESULTS: The human CA1, AQP, band-3 protein and H+-transport proteins revealed similar proteins in Acanthamoeba. Docking showed the binding of AZM on amoebal AQP-like proteins.  Acanthamoeba showed transient shape changes and encystation at differential doses of brinzolamide, mannitol and AZM.  Conclusion: Water and pH regulating adapter proteins in Acanthamoeba and humans show significant homology, these mechanisms evolved early in the primitive unicellular eukaryotes and have remained conserved in multicellular eukaryotes.

A melt castable energetic cocrystal.

An energetic cocrystal is described between 3,4-diaminofurazan (DAF) and 4-amino-3,5-dinitropyrazole (ADNP). The material is remarkable because interaction between the components leads to melting behavior and melt-state stabilization (absent in ADNP), that allows a melt castable formulation with explosive performance superior to DAF. This provides another potential advantage of cocrystallization for energetic materials.