Risk Score to Predict 1-Year Mortality after Haemodialysis Initiation in Patients with Stage 5 Chronic Kidney Disease under Predialysis Nephrology Care

Background

Few risk scores are available for predicting mortality in chronic kidney disease (CKD) patients undergoing predialysis nephrology care. Here, we developed a risk score using predialysis nephrology practice data to predict 1-year mortality following the initiation of haemodialysis (HD) for CKD patients.

Methods

This was a multicenter cohort study involving CKD patients who started HD between April 2006 and March 2011 at 21 institutions with nephrology care services. Patients who had not received predialysis nephrology care at an estimated glomerular filtration rate (eGFR) of approximately 10 mL/min per 1.73 m² were excluded. Twenty-nine candidate predictors were selected, and the final model for 1-year mortality was developed via multivariate logistic regression and was internally validated by a bootstrapping technique.

Results

A total of 688 patients were enrolled, and 62 (9.0%) patients died within one year of HD initiation. The following variables were retained in the final model: eGFR, serum albumin, calcium, Charlson Comorbidity Index excluding diabetes and renal disease (modified CCI), performance status (PS), and usage of erythropoiesis-stimulating agent (ESA). Their β-coefficients were transformed into integer scores: three points were assigned to modified CCI≥3 and PS 3–4; two to calcium>8.5 mg/dL, modified CCI 1–2, and no use of ESA; and one to albumin<3.5 g/dL, eGFR>7 mL/min per 1.73 m², and PS 1–2. Predicted 1-year mortality risk was 2.5% (score 0–4), 5.5% (score 5–6), 15.2% (score 7–8), and 28.9% (score 9–12). The area under the receiver operating characteristic curve was 0.83 (95% confidence interval, 0.79–0.89).

Conclusions

We developed a simple 6-item risk score predicting 1-year mortality after the initiation of HD that might help nephrologists make a shared decision with patients and families regarding the initiation of HD.     

Increase in Ultrasonic Intensity of Blood Speckle across Moderate Coronary Artery Stenosis Is an Independent Predictor of Functional Coronary Artery Stenosis Measured by Fractional Flow Reserve: Pilot Study

Background and Aims

The degree of coronary artery stenosis should be assessed both anatomically and functionally. We observed that the intensity of blood speckle (IBS) on intravascular ultrasound (IVUS) is low proximal to a coronary artery stenosis, and high distal to the stenosis. We defined step-up IBS as the distal minus the proximal IBS, and speculated that this new parameter could be used for the functional evaluation of stenosis on IVUS. The aims of this study were to assess the relationships between step-up IBS and factors that affect coronary blood flow, and between step-up IBS and fractional flow reserve (FFR).

Methods and Results

This study enrolled 36 consecutive patients with angina who had a single moderate stenosis in the left anterior descending artery. All patients were evaluated by integrated backscatter IVUS and intracoronary pressure measurements. FFR was calculated from measurements using a coronary pressure wire during hyperemia. Conventional gray-scale IVUS images were recorded, and integrated backscatter was measured in three cross-sectional slices proximal and distal to the stenosis. Step-up IBS was calculated as (mean distal integrated backscatter value) − (mean proximal integrated backscatter value). Stepwise multiple linear regression analysis showed that the heart rate (r = 0.45, P = 0.005), ejection fraction (r = −0.39, P = 0.01), and hemoglobin level (r = −0.32, P = 0.04) were independently correlated with step-up IBS, whereas proximal and distal IBS were not associated with these factors. There was a strong inverse correlation between step-up IBS and FFR (r = −0.84, P < 0.001), which remained significant on stepwise multiple linear regression analysis.

Conclusions

The newly defined parameter of step-up IBS is potentially useful for the functional assessment of coronary artery stenosis.     

Metabolism and Long-distance Translocation of Cytokinins

During plant development, distantly-located organs must communicate in order to adapt morphological and physiological features in response to environmental inputs. Among the recognized signaling molecules, a class of phytohormones known as the cytokinins functions as both local and long-distance regulatory signals for the coordination of plant development. This cytokinin-dependent communication system consists of orchestrated regulation of the metabolism, translocation, and signal transduction of this phytohormone class. Here, to gain insight into this elaborate signaling system, we summarize current models of biosynthesis, trans-membrane transport, and long-distance translocation of cytokinins in higher plants.     

Characterization of a unique GATA family gene that responds to both light and cytokinin in Arabidopsis thaliana

For higher plants, light is an important external signal, whereas cytokinin acts as an internal hormonal signal, and both are crucial for almost all aspects of development and physiological states. Here we identified and characterized a unique gene, CGA1, encoding a GATA factor, whose expression was rapidly induced by both the light and cytokinin signals in Arabidopsis thaliana.     

Nuclear-translocated Glyceraldehyde-3-phosphate Dehydrogenase Promotes Poly(ADP-ribose) Polymerase-1 Activation during Oxidative/Nitrosative Stress in Stroke

In addition to its role in DNA repair, nuclear poly(ADP-ribose) polymerase-1 (PARP-1) mediates brain damage when it is over-activated by oxidative/nitrosative stress. Nonetheless, it remains unclear how PARP-1 is activated in neuropathological contexts. Here we report that PARP-1 interacts with a pool of glyceradehyde-3-phosphate dehydrogenase (GAPDH) that translocates into the nucleus under oxidative/nitrosative stress both in vitro and in vivo. A well conserved amino acid at the N terminus of GAPDH determines its protein binding with PARP-1. Wild-type (WT) but not mutant GAPDH, that lacks the ability to bind PARP-1, can promote PARP-1 activation. Importantly, disrupting this interaction significantly diminishes PARP-1 overactivation and protects against both brain damage and neurological deficits induced by middle cerebral artery occlusion/reperfusion in a rat stroke model. Together, these findings suggest that nuclear GAPDH is a key regulator of PARP-1 activity, and its signaling underlies the pathology of oxidative/nitrosative stress-induced brain damage including stroke.     

Artificial extracellular matrix proteins containing phenylalanine analogues biosynthesized in bacteria using T7 expression system and the PEGylation

In vivo incorporation of phenylalanine (Phe) analogues into an artificial extracellular matrix protein (aECM-CS5-ELF) was accomplished using a bacterial expression host that harbors the mutant phenylalanyl-tRNA synthetase (PheRS) with an enlarged binding pocket. Although the Ala294Gly/Thr251Gly mutant PheRS (PheRS**) under the control of T5 promoter allows incorporation of some Phe analogues into a protein, the T5 system is not suitable for material science studies because the amount of materials produced is not sufficient due to the moderate strength of the T5 promoter. This limitation can be overcome by using a pair of T7 promoter and T7 RNA polymerase instead. In the T7 expression system, it is difficult, however, to achieve a high incorporation level of Phe analogues, due to competition of Phe analogues for incorporation with the residual Phe that is required for synthesis of active T7 RNA polymerase. In this study, we prepared the PheRS** under T7 promoter and optimized culture condition to improve both the incorporation level of recombinant aECM protein and the incorporation level of Phe analogues. Incorporation and expression levels tend to increase in the case of p-azidophenylalanine, p-iodophenylalanine, and p-acetylphenylalanine. We evaluated the lower critical transition temperature, which is dependent on the incorporation ratio and the turbidity decreased when the incorporation level increased. Circular dichromism measurement indicated that this tendency is based on conformational change from random coil to β-turn structure. We demonstrated that polyethylene glycol (PEG) can be conjugated at reaction site of Phe analogues incorporated. We also demonstrated that the increased hydrophilicity of elastin-like sequences in the aECM-CS5-ELF made by PEG conjugation could suppress nonspecific adhesion of human umbilical vein endothelial cells (HUVEC).     

Thermostability of ancestral mutants of Caldococcus noboribetus isocitrate dehydrogenase

We constructed mutant genes of Caldococcus noboribetus isocitrate dehydrogenase containing ancestral amino acid residues that were inferred using the maximal likelihood method and a composite phylogenetic tree of isocitrate dehydrogenase and 3-isopropylmalate dehydrogenase. The mutant genes were expressed in Escherichia coli and the protein products purified. Thermostabilities, reported as the half-inactivation temperatures, for the purified enzymes were determined and compared with that of the wild-type enzyme. Four of the five mutant enzymes have greater thermal stabilities than wild-type isocitrate dehydrogenase. The results are compatible with the hyperthermophilic universal ancestor (commonote) hypothesis. Incorporation of ancestral residues into a modern-day protein sequence can be used to improve protein thermostability.     

Identification of putative metabolites of docosahexaenoic acid as potent PPARgamma agonists and antidiabetic agents

We found that putative metabolites of docosahexaenoic acid (DHA) are strong PPARgamma activators and potential antidiabetic agents. We designed DHA derivatives based on the crystal structure of PPARgamma, synthesized them and evaluated their activities in vitro and in vivo. The efficacy of 5E-4-hydroxy-DHA 2a as a PPARgamma activator was about fourfold stronger than that of pioglitazone. Furthermore, the 4-keto derivative (10b) showed antidiabetic activity in animal models without producing undesirable effects such as obesity and hepatotoxicity.     

The involvement of neutrophils in the resistance to Leishmania major infection in susceptible but not in resistant mice

To understand the immunomodulatory roles of neutrophils in Leishmania major infection, we examined the expression of cytokine and chemokine mRNAs from neutrophils of the infected resistant C3H/HeJ and susceptible BALB/c mice. We also examined the effects of neutrophil depletion on the expression of cytokine by peritoneal macrophages and draining lymph node cells and on the footpad lesions and parasite burdens in these mice. Neutrophils from resistant C3H/HeJ but not from susceptible BALB/c mice expressed mRNAs for IL-12p40, IFN-gamma,TNF-alpha and monokine induced by IFN-gamma(MIG). Neutrophil depletion of the resistant mice reduced the expression of IFN-gammaandTNF-alpha in peritoneal macrophages but did not affect the expression of IL-12p40 and IFN-gamma in draining lymph node cells and the growth of footpad lesions. On the other hand, neutrophil depletion of susceptible BALB/c mice did not affect the expression of TNF-alpha and monocyte-derived chemokine (MDC) in peritoneal macrophages but induced the early stage expression of IL-4 in draining lymph node cells and exacerbated the footpad lesions and increased the parasite burden. The exacerbation of footpad lesions induced by neutrophil depletion was abolished by rIL-12 treatment. Our results suggest that even in susceptible BALB/c but not in C3H/HeJ mice there is a certain resistance requiring neutrophils at the early stage of infection.