[Sudden Chest Pain due to Early Bioprosthetic Valve Dysfunction:Report of a Case].

We report a case of bioprosthetic valve dysfunction and acute aortic valve regurgitation. The case was a 75-year-old female who had sudden onset chest pain. ST-segment depression in several leads on electrocardiogram( ECG) suggested acute coronary syndrome. Coronary angiography showed no significant stenosis in coronary arteries. Transesophageal echocardiography revealed severe aortic regurgitation, suggesting that angina was caused by myocardial ischemia associated with acute aortic regurgitation. She was diagnosed as having bioprosthetic valve dysfunction, and underwent redo aortic valve replacement. One leaflet of the bioprosthetic valve was torn along the stent post and caused bioprosthetic valve dysfunction. Failed bioprosthetic valve was removed and replaced by a mechanical valve.

[Traumatic Ascending Aortic Injury with Delayed Cardiac Tamponade due to Sternal Fracture].

The case was a 63-year-old male. He had a history of surgery for funnel chest at the age of 23. He overdrank and hit the anterior chest about two weeks before. He complained of persistent chest pain and palpitation, and was admitted because of atrial fibrillation and moderate pericardial fluid. Computed tomography (CT) showed a new sternal fracture, but dislocation and instability was mild. A few days later, sinus rhythm was restored and his heart failure improved. Unfortunately, on the 7th day, he suddenly suffered cardiopulmonary arrest. Ultrasonography revealed cardiac tamponade, and pericardiocentesis yielded 400 ml of bloody pericardial fluid collection. CT demonstrated clot mainly in the anterior pericardium, and emergent operation was performed. Bleeding from the anterior wall of the ascending aorta was repaired by placing one stitch. Postoperatively the patient remained unconscious, and CT of the brain showed hypoxic encephalopathy. After prolonged ventilator management, he was transferred to a rehabilitation hospital. In retrospect, the ascending aorta was close to the sternum in this patient, and sternal fracture might have caused injury of the ascending aorta.

DnaK promotes autophosphorylation of DYRK1A and its family kinases in Escherichia coli-based cell-free protein expression.

Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is one of the drug target kinases involved in neurological disorders. DYRK1A phosphorylates substrate proteins related to disease progression in an intermolecular manner. Meanwhile, DYRK1A intramolecularly phosphorylates its own residues on key segments during folding process, which is required for its activation and stabilization. To reproduce the autophosphorylation in vitro, DYRK1A was expressed in Escherichia coli-based cell-free protein synthesis system. Although this system was useful for investigating autophosphorylation of serine residue at position 97 (Ser97) in DYRK1A, only a small fraction of the synthesized protein was successfully autophosphorylated. In this study, we found that the addition of DnaK, a bacterial HSP70 chaperone, to cell-free expression of DYRK1A promoted its Ser97 autophosphorylation. Structure prediction with AlphaFold2 indicates that Ser97 forms a hydrogen bond within an α-helix structure, indicating a possibility that DnaK unfolds the α-helix and maintains the structure around Ser97 in a conformation susceptible to phosphorylation. In addition, DnaK promoted phosphorylation of DYRK1B and HIPK2, but not DYRK2 and DYRK4, suggesting a sequence selectivity in the action of DnaK. This study provides a facile method for promoting autophosphorylation of DYRK family kinases in cell-free protein expression.

Expression and purification of DYRK1A kinase domain in complex with its folding intermediate-selective inhibitor FINDY.

The kinase DYRK1A phosphorylates substrate proteins that are involved in the progression of many diseases. DYRK1A also phosphorylates its own residues on key elements intramolecularly to activate and stabilize itself during the folding process. Once the folding process of DYRK1A has completed, it can no longer catalyzes the intramolecular reaction, suggesting that a transitional intermediate state that catalyzes the autophosphorylation exists. In the previous study, we identified a small molecule, designated as FINDY, that selectively inhibits the folding intermediate of DYRK1A. Although evidence has suggested that FINDY targets the ATP-binding pocket of DYRK1A, it remains elusive as to whether the DYRK1A kinase domain could be purified as a complex with FINDY. In this study, we successfully expressed and purified the kinase domain of DYRK1A in complex with FINDY. The DYRK1A kinase domain was expressed as a fusion protein with a hexahistidine tag and ZZ-domain (His-ZZ-DYRK1A) at 6 °C by using a cold shock induction system in Escherichia coli cells. The cells were incubated with FINDY. The cell pellets were gently extracted on ice and subjected to immobilized-metal affinity chromatography. The amount of FINDY in the elution fraction was measured by UV absorbance specific for FINDY. The eluate contained FINDY with the ratio of FINDY to DYRK1A protein being 0.15 in quadruplicate experiments. Thus, this study demonstrates the direct interaction between the DYRK1A kinase domain and FINDY, paving the way for structural determination of the complex.

Efficacy of Plasma free Hemoglobin for detecting centrifugal pump thrombosis.

INTRODUCTION: Lactate dehydrogenase (LDH) is widely used as an indicator of pump thrombosis in a centrifugal pump. However, due to the low specificity of LDH, pump thrombosis is difficult to detect in the clinical environment. We measured plasma free hemoglobin (pfHb) with the portable device in ICU. The goal of this investigation is to evaluate its diagnostic ability for pump thrombosis. METHODS: We enrolled 31 consecutive patients who needed Extracorporeal Membrane Oxygenation (ECMO) therapy and pfHb was determined with HemoCue® plasma/Low Hb photometer. Pump thrombosis was analyzed macroscopically at the timing of pump explantation or exchange. Also, we divided the pump thrombosis into a grading scale by the place of thrombosis. RESULTS: The median of peak pfHb was significantly lower in the none thrombus group (0.03 g/dL) than that of in the thrombus group (0.05g/dL) (p = 0.01). In our grading criteria, pfHb was significantly higher when the thrombus is existing near the shaft (p = 0.015). Contrary, no significant difference was found for LDH.The ROC analysis of pfHb revealed an AUC of 0.77 for detecting pump thrombosis with the best statistical cutoff value at 0.05 g/dL (specificity, 78%; sensitivity, 77%). Also, ROC analysis of LDH was performed (AUC, 0.44; cutoff value, 1200 IU/L; specificity, 59%; sensitivity, 54%) and compared with pfHb. AUC was significantly higher in pfHb (p = 0.04). CONCLUSION: Our results showed the efficacy of pfHb for detecting centrifugal pump thrombosis.

Darbepoetin alfa (KRN321) is safe and effective when administered subcutaneously once every 2 or 4 weeks to patients on peritoneal dialysis in Japan.

BACKGROUND: Darbepoetin alfa (KRN321) is a recombinant protein that stimulates erythropoiesis by the same mechanism as endogenous erythropoietin. Due to its longer half-life and greater biological activity than recombinant human erythropoietin (rHuEPO), KRN321 maintains an effective hemoglobin (Hb) level at extended dose intervals compared with rHuEPO. The efficacy and safety of KRN321 administered subcutaneously to patients on peritoneal dialysis (PD) were tested. METHODS: In a multicenter, open-label, single-arm study, KRN321 was administered subcutaneously to patients on PD for 26-28 weeks. Ninety-six patients initially were given a 60 µg subcutaneous dose once every 2 weeks until a target of Hb (11.0-13.0 g/dL) was achieved. Thereafter, their dose was every 2 or 4 weeks. RESULTS: After the target of Hb was reached in most subjects (96.9%), it was maintained with KRN321 administered every 2 or 4 weeks. On completion of (or withdrawal from) study, 65 subjects (67.7%) maintained the target Hb. Although a number of adverse event related to hypertension occurred, their incidence did not appear to be related to Hb or its rate of increase. These events could be controlled adequately by interrupting or reducing the dose, and/or treatment with antihypertensives. CONCLUSIONS: The efficacy and safety of KRN321 when administered subcutaneously for 28 weeks to PD patients were confirmed. It was suggested that the quality of life of patients can be improved by treatment with KRN321 due to the reduced frequency of administration.