Successful withdrawal of catecholamine with ivabradine administration in catecholamine-dependent heart failure.

Ivabradine is a heart rate (HR)-lowering agent that blocks hyperpolarization-activated cyclic nucleotide-gated channel in the sinus node without a negative inotropic effect on cardiac function. Here we report a case of catecholamine-dependent heart failure, who was intolerant to ß blockers, and successfully withdrew catecholamine by administering ivabradine. A 39-year-old male acute decompensated heart failure (ADHF) patient with severe systolic cardiac failure, refractory to diuretic and dobutamine treatment was transferred to our hospital. In addition to titration of dobutamine support, intra-aortic balloon pump, mechanical ventilation, and continuous hemodiafiltration therapy were initiated. These mechanical supports could stabilize ADHF and were removed. Upon stabilization of ADHF, we attempted to initiate a low dose of bisoprolol and taper dobutamine, but the patient could not tolerate even a low dose of bisoprolol nor tapering of dobutamine. Since his HR was consistently above 100 beats per minute and ivabradine was reported to improve stroke volume (SV), we initiated ivabradine, and his SV remarkably increased after initiation. Consequently, the dose of dobutamine was successfully tapered. Also, additional clinical advantage of ivabradine, assessed through hemodynamic parameters, appeared to be a reduction in afterload. .

Clinical utility of reticulocyte hemoglobin equivalent in patients with heart failure.

Anemia and iron deficiency (ID) are common in patients with heart failure (HF) and intravenous (IV) administration of iron to patients hospitalized for decompensated HF with ID improves outcome. The diagnosis of ID in routine practice is based on serum ferritin and transferrin saturation (TSAT) but both have limitations; alternatives should be considered. Reticulocyte hemoglobin equivalent (Ret-He) reflects iron content in reticulocytes but its clinical utility in patients with HF remains uncertain. We prospectively enrolled 142 patients hospitalized for decompensated HF. Sixty five percent had ID as defined in current international guidelines. Ret-He was directly correlated with serum iron and ferritin concentrations and with TSAT. There was a poor relationship between quartile of Ret-He and HF hospitalization or death but increases or decreases in Ret-He between admission and discharge were associated with a worse outcome. The clinical utility of Ret-He for identifying ID and predicting response to IV iron and prognosis for patients with HF requires further investigation.

Biochemical properties and base excision repair complex formation of apurinic/apyrimidinic endonuclease from Pyrococcus furiosus.

Apurinic/apyrimidinic (AP) sites are the most frequently found mutagenic lesions in DNA, and they arise mainly from spontaneous base loss or modified base removal by damage-specific DNA glycosylases. AP sites are cleaved by AP endonucleases, and the resultant gaps in the DNA are repaired by DNA polymerase/DNA ligase reactions. We identified the gene product that is responsible for the AP endonuclease activity in the hyperthermophilic euryarchaeon, Pyrococcus furiosus. Furthermore, we detected the physical interaction between P. furiosus AP endonuclease (PfuAPE) and proliferating cell nuclear antigen (PCNA; PfuPCNA) by a pull-down assay and a surface plasmon resonance analysis. Interestingly, the associated 3'-5' exonuclease activity, but not the AP endonuclease activity, of PfuAPE was stimulated by PfuPCNA. Immunoprecipitation experiments using the P. furiosus cell extracts supported the interaction between PfuAPE and PfuPCNA in the cells. This is the first report describing the physical and functional interactions between an archaeal AP endonuclease and PCNA. We also detected the ternary complex of PfuPCNA, PfuAPE and Pfu uracil-DNA glycosylase. This complex probably functions to enhance the repair of uracil-containing DNA in P. furiosus cells.

Anemia has an impact on prognosis in heart failure with preserved ejection fraction with mild chronic kidney disease.

BACKGROUND: Anemia and chronic kidney disease (CKD) are common in patients with heart failure with preserved left ventricular fraction (HFpEF). However, it is entirely unknown about the impact of anemia on prognosis in HFpEF patients with CKD. In this study, we investigated the impact of anemia on prognosis and the optimal hemoglobin (Hb) levels to predict prognosis in HFpEF patients with CKD. METHODS AND RESULTS: We prospectively examined 523 consecutive HFpEF patients enrolled in Japanese heart failure syndrome with preserved ejection fraction registry. CKD was defined as an estimated glomerular filtration rate (eGFR) of <60 mL /min/1.73 m2. The prevalence rate of anemia was 78% in HFpEF patients with CKD by using the World Health Organization criteria. Kaplan-Meier analysis for all-cause mortality and heart failure rehospitalization demonstrated that anemic patients had poor prognosis compared with non-anemic patients in HFpEF patients with CKD, but not those without CKD. According to the degree of CKD, anemia affected prognosis in HFpEF patients with mild CKD (45 ≤ eGFR < 60), but not those with moderate to severe CKD (15 ≤ eGFR < 45). Additionally, multivariate analysis revealed that anemia and Hb levels were independent predictors of composite outcomes in HFpEF patients with mild CKD, but not those with moderate to severe CKD. Finally, survival classification and regression tree analysis showed that the optimal Hb levels to predict composite outcomes were 10.7 g/dL in those with mild CKD. CONCLUSIONS: Anemia has an impact on prognosis in HFpEF patients, especially among those with mild CKD.

Studies on the base excision repair (BER) complex in Pyrococcus furiosus.

We have been studying the functions of PCNA (proliferating-cell nuclear antigen) for the assembly and reassembly of the replisome during replication fork progression. We have identified the functional interactions between PCNA and several proteins involved in DNA replication and repair from Pyrococcus furiosus. We recently reported that the activity of UDG (uracil-DNA glycosylase) in P. furiosus (PfuUDG) is stimulated by PCNA (PfuPCNA) in vitro, and identified an atypical PCNA-binding site, AKTLF, in the PfuUDG protein. To understand further the function of the complex in the BER (base excision repair) process, we investigated the AP (apurinic/apyrimidinic) endonuclease, which can process the BER pathway after uracil removal by UDG. Interestingly, one candidate ORF (open reading frame) for the AP endonuclease was found in the operon containing the gene encoding UDG in the P. furiosus genome. However, this ORF did not exhibit any activity. Instead, we identified the AP endonuclease activity from the other candidate gene products, and designated the protein as PfuAP. We discovered a physical interaction between PfuAP and PfuPCNA, suggesting the formation of a BER complex in one of the repair systems in P. furiosus.

A novel single-strand specific 3'-5' exonuclease found in the hyperthermophilic archaeon, Pyrococcus furiosus.

Nucleases play important roles in all DNA transactions, including replication, repair, and recombination. Many different nucleases from bacterial and eukaryotic organisms have been identified and functionally characterized. However, our knowledge about the nucleases from Archaea, the third domain of life, is still limited. We searched for 3'-5' exonuclease activity in the hyperthermophilic archaeon, Pyrococcus furiosus, and identified a protein with the target activity. The purified protein, encoded by PF2046, is composed of 229 amino acids with a molecular weight of 25,596, and displayed single-strand specific 3'-5' exonuclease activity. The protein, designated as PfuExo I, forms a stable trimeric complex in solution and excises the DNA at every two nucleotides from the 3' to 5' direction. The amino acid sequence of this protein is conserved only in Thermococci, one of the hyperthermophilic classes in the Euryarchaeota subdomain in Archaea. The newly discovered exonuclease lacks similarity to any other proteins with known function, including hitherto reported 3'-5' exonucleases. This novel nuclease may be involved in a DNA repair pathway conserved in the living organisms as a specific member for some hyperthermophilic archaea.