Renal Function Trajectories in Patients with Prior Improved eGFR Slopes and Risk of Death

Background

Multiple prior studies demonstrated that patients with early Chronic Kidney Disease (CKD) and positive estimated Glomerular Filtration Rate (eGFR) slopes experience increased risk of death. We sought to characterize patients with positive eGFR slopes, examine the renal function trajectory that follows the time period where positive slope is observed, and examine the association between different trajectories and risk of death.

Methods and Findings

We built a cohort of 204,132 United States veterans with early CKD stage 3; eGFR slopes were defined based on Bayesian mixed-effects models using outpatient eGFR measurements between October 1999 and September 2004; to build renal function trajectories, patients were followed longitudinally thereafter (from October 2004) until September 2013. There were 41,410 (20.29%) patients with positive eGFR slope and they exhibited increased risk of death compared to patients with stable eGFR slope (HR = 1.33, CI:1.31–1.35). There was an inverse graded association between severity of albuminuria and the odds of positive eGFR slope (OR = 0.94, CI:0.90–0.98, and OR = 0.76, CI:0.69–0.84 for microalbuminuria and albuminuria; respectively). Following the time period where positive eGFR slope is observed, we characterized 4 trajectory phenotypes: high eGFR intercept and positive trajectory (HIPT) (12.42%), intermediate intercept and mild negative trajectory (IIMNT) (60.04%), low intercept and fast negative trajectory (LIFNT)(23.33%), and high intercept and fast negative trajectory (HIFNT) (4.20%). Compared to IIMNT (reference group), HIPT is associated with younger age, dementia, HIV, chronic lung disease, peripheral artery disease, weight loss, and inversely associated with albuminuria; LIFNT and HIFNT were associated with diabetes, hypertension, cardiovascular disease, peripheral artery disease, and albuminuria. The risk of death at 9 years was lowest in IIMNT (HR = 1.12, CI:1.09–1.14), highest in HIPT (HR = 1.71, CI:1.63–1.79), and intermediate in LIFNT (HR = 1.36, CI:1.32–1.40) and HIFNT (HR = 1.56, CI:1.45–1.68).

Conclusions

Our results demonstrate that patients with positive eGFR slopes, when followed over longer period of time, follow 4 distinct trajectory phenotypes that have distinct demographic and clinical correlates and are differentially associated with risk of death.     

Translating cancer research by synthetic biology

Synthetic biology concerns applying engineering principles to biological systems. Engineering properties such as fine tuning, novel specificity, and modularity could be components of a synthetic toolkit that can be exploited to explore various issues in cancer research such as elucidation of mechanisms and pathways, creating new diagnostic tools and novel therapeutic approaches. A repertoire of synthetic biology toolkits involving DNA, RNA and protein bio-parts, have been applied to address the issues of drug target identification, drug discovery and therapeutic treatment in cancer research, thereby projecting a new dimension in oncology research.     

Roles of lysophosphatidic acid in cardiovascular physiology and disease

The bioactive lipid mediator lysophosphatidic acid (LPA) exerts a range of effects on the cardiovasculature that suggest a role in a variety of critical cardiovascular functions and clinically important cardiovascular diseases. LPA is an activator of platelets from a majority of human donors identifying a possible role as a regulator of acute thrombosis and platelet function in atherogenesis and vascular injury responses. Of particular interest in this context, LPA is an effective phenotypic modulator of vascular smooth muscle cells promoting the de-differentiation, proliferation and migration of these cells that are required for the development of intimal hyperplasia. Exogenous administration of LPA results in acute and systemic changes in blood pressure in different animal species, suggesting a role for LPA in both normal blood pressure regulation and hypertension. Advances in our understanding of the molecular machinery responsible for the synthesis, actions and inactivation of LPA now promise to provide the tools required to define the role of LPA in cardiovascular physiology and disease. In this review we discuss aspects of LPA signaling in the cardiovasculature focusing on recent advances and attempting to highlight presently unresolved issues and promising avenues for further investigation.     

p53 Regulates oxidative stress-mediated retrograde signaling: a novel mechanism for chemotherapy-induced cardiac injury

The side effects of cancer therapy on normal tissues limit the success of therapy. Generation of reactive oxygen species (ROS) has been implicated for numerous chemotherapeutic agents including doxorubicin (DOX), a potent cancer chemotherapeutic drug. The production of ROS by DOX has been linked to DNA damage, nuclear translocation of p53, and mitochondrial injury; however, the causal relationship and molecular mechanisms underlying these events are unknown. The present study used wild-type (WT) and p53 homozygous knock-out (p53(-/-)) mice to investigate the role of p53 in the crosstalk between mitochondria and nucleus. Injecting mice with DOX (20 mg/kg) causes oxidative stress in cardiac tissue as demonstrated by immunogold analysis of the levels of 4-hydroxy-2'-nonenal (4HNE)-adducted protein, a lipid peroxidation product bound to proteins. 4HNE levels increased in both nuclei and mitochondria of WT DOX-treated mice but only in nuclei of DOX-treated p53((-/-)) mice, implicating a critical role for p53 in causing DOX-induced oxidative stress in mitochondria. The stress-activated protein c-Jun amino-terminal kinase (JNKs) was activated in response to increased 4HNE in WT mice but not p53((-/-)) mice receiving DOX treatment, as determined by co-immunoprecipitation of HNE and pJNK. The activation of JNK in DOX treated WT mice was accompanied by Bcl-2 dissociation from Beclin in mitochondria and induction of type II cell death (autophagic cell death), as evidenced by an increase in LC3-I/LC-3-II ratio and γ-H2AX, a biomarker for DNA damage. The absence of p53 significantly reduces mitochondrial injury, assessed by quantitative morphology, and decline in cardiac function, assessed by left ventricular ejection fraction and fraction shortening. These results demonstrate that p53 plays a critical role in DOX-induced cardiac toxicity, in part, by the induction of oxidative stress mediated retrograde signaling.     

Comparative Expression Profiling Reveals an Essential Role for Raldh2 in Epimorphic Regeneration

Zebrafish have the remarkable ability to regenerate body parts including the heart and fins by a process referred to as epimorphic regeneration. Recent studies have illustrated that similar to adult zebrafish, early life stage larvae also possess the ability to regenerate the caudal fin. A comparative microarray analysis was used to determine the degree of conservation in gene expression among the regenerating adult caudal fin, adult heart, and larval fin. Results indicate that these tissues respond to amputation/injury with strikingly similar genomic responses. Comparative analysis revealed raldh2, a rate-limiting enzyme for the synthesis of retinoic acid, as one of the most highly induced genes across the three regeneration platforms. In situ localization and functional studies indicate that raldh2 expression is critical for the formation of wound epithelium and blastema. Patterning during regenerative outgrowth was considered to be the primary function of retinoic acid signaling; however, our results suggest that it is also required for early stages of tissue regeneration. Expression of raldh2 is regulated by Wnt and fibroblast growth factor/ERK signaling.     

Curcumin modulates free radical quenching in myocardial ischaemia in rats

This study was designed to investigate the protective effect of curcumin (CUR) against isoprenaline induced myocardial ischaemia in rat myocardium. The effect of single oral dose of curcumin (15 mg kg(-1)), administered 30 min before and/or after the onset of ischaemia, was investigated by assessing oxidative stress related biochemical parameters in rat myocardium. Curcumin pre and post-treatment (PPT) was shown to decrease the levels of xanthine oxidase, superoxide anion, lipid peroxides (LPs) and myeloperoxidase while the levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) activities were significantly increased after curcumin PPT. Histopathological and transmission electron microscopical studies also confirmed the severe myocardial damage occurring as a consequence of isoprenaline induced ischaemia and they also showed the significant improvement effected by curcumin PPT. These findings provided evidence that curcumin was found to protect rat myocardium against ischaemic insult and the protective effect could be attributed to its antioxidant properties as well as its inhibitory effects on xanthine dehydrogenase/xanthine oxidase (XD/XO) conversion and resultant superoxide anion production.     

Synthesis and evaluation of antioxidative properties of a series of organoselenium compounds

A series of organoselenocyanate compounds 4a-d were synthesized utilizing 1,8-naphthalic anhydride as the building unit. These compounds were evaluated for their antioxidative activities against DMBA-PMA-induced oxidative stress in a two-stage mouse skin carcinogenic model. Compound 4d was found to have the maximum antioxidative property in comparison with the other compounds. Also, the pretreatment group showed better results than the concomitant treatment groups.     

In vitro regeneration of Ruscus hypophyllum L. plants

Callus cultures were established from stem explants of Ruscus hypophyllum on a modified basal medium of Murashige and Skoog (1962) supplemented with 1 mg l^-1 2,4-D+0.1 mg l^-1 BAP. The optimal 2,4-D concentration for promoting shoot bud formation and growth was 0.05 mg l^-1 along with 0.5 mg l^-1 BAP. Sixty percent of rootless shoots produced flowers on the regenerating medium. Rooting was induced when shoots were transferred to half strength MS inorganic salts supplemented with 2 mg l^-1 IBA. Eighty percent of plants transferred to soil have survived.     

Promoter polymorphism MMP-1 (-1607 2G/1G) and MMP-3 (-1612 5A/6A) in development of HAND and modulation of pathogenesis of HAND

The pathogenesis of HIV-associated neurocognitive disorder (HAND) is modulated by host genetic susceptibility factors such as Matrix metalloproteinases (MMPs). Promoter polymorphism of MMP-1 and MMP-3 may modify the expression of the gene. Hence, we evaluated the association of MMP-1-16072G/1G and MMP-3-1612 5A/6A polymorphisms with development of HAND and the modulation of pathogenesis of HAND. We enrolled a total of 180 individuals, 50 HIV-infected individuals with HAND, 130 without HAND, and 150 healthy controls. Polymorphism of MMP-1 and MMP-3 were genotyped by PCR-RFLP. MMP-1-1607 2G1G, -16071G/2G-1G/1G genotypes and -1607 1G allele were associated with the development of HAND (OR = 1.64, P = 0.05; OR = 1.45, P = 0.04; OR = 1.69, P = 0.05). MMP-1-16071G1G, MMP-3-16125A5A genotypes increased the risk for the development of HAND (OR = 1.78, P = 0.25; OR = 2.39, P = 0.13). MMP-3-1612 5A5A, -1612 6A/5A-5A/5A genotypes and -1612 5A allele were associated with the reduced risk of HAND (OR = 0.40, P = 0.05; OR = 0.53, P = 0.04; OR = 0.40, P = 0.01). Haplotype 5A1G increased the risk of development of HAND (OR = 1.93, P = 0.05). As observed in advanced HIV disease stage, MMP-1-1607 1G1G genotype enhance the risk for advancement of HIV disease (OR = 1.69, P = 0.89). MMP-3-1612 6A5A genotype showed higher risk for development of HAND in alcohol users (0R = 1.65, P = 0.44). MMP-1 genotype may have an influence on development of HAND whereas MMP3-1612 5A5A genotype may reduce risk for pathogenesis of HAND.