Pre-Dialysis Visits to a Nephrology Department and Major Cardiovascular Events in Patients Undergoing Dialysis

Background and Objectives

Pre-dialysis care by a nephrology out-patient department (OPD) may affect the outcomes of patients who ultimately undergo maintenance dialysis. This study examined the effect of pre-dialysis care by a nephrology OPD on the incidence of one-year major cardiovascular events after initiation of dialysis.

Design, Setting Participants, & Measurements

The study consisted of Taiwanese patients with chronic kidney disease (CKD) who commenced dialysis from 2006 to 2008. The number of nephrology OPD visits during the critical care period (within 6 months of initiation of dialysis) and the early care period (6–36 months before initiation of dialysis) were analyzed. The primary outcome measure was one-year major cardiovascular events.

Results

A total of 1191 CKD patients who initiated dialysis from 2006 to 2008 were included. Binary logistic regression showed that patients with ≧3 visits during the critical care period and those with ≧11 visits during the early care period had fewer composite major cardiovascular events than those with 0 visits. Patients with early referral are less likely to experience composite major cardiovascular events than those with late referral, with aOR 0.574 (95% CI = 0.43–0.77, P<0.001). Patients with both ≧3 visits during critical care period and ≧11 visits during early care period were less likely to experience composite major cardiovascular events (aOR = 0.25, 95% CI = 0.16–0.39, P < 0.001).

Conclusions

Patients with adequate pre-dialysis nephrology OPD visits, not just early referral, may had fewer one-year composite major cardiovascular events after initiation of dialysis. This information may be important to medical care providers and public health policy makers in their efforts to improve the well-being of CKD patients.     

A transgenic plant cell‐suspension system for expression of epitopes on chimeric Bamboo mosaic virus particles

We describe a novel strategy to produce vaccine antigens using a plant cell‐suspension culture system in lieu of the conventional bacterial or animal cell‐culture systems. We generated transgenic cell‐suspension cultures from Nicotiana benthamiana leaves carrying wild‐type or chimeric Bamboo mosaic virus (BaMV) expression constructs encoding the viral protein 1 (VP1) epitope of foot‐and‐mouth disease virus (FMDV). Antigens accumulated to high levels in BdT38 and BdT19 transgenic cell lines co‐expressing silencing suppressor protein P38 or P19. BaMV chimeric virus particles (CVPs) were subsequently purified from the respective cell lines (1.5 and 2.1 mg CVPs/20 g fresh weight of suspended biomass, respectively), and the resulting CVPs displayed VP1 epitope on the surfaces. Guinea pigs vaccinated with purified CVPs produced humoral antibodies. This study represents an important advance in the large‐scale production of immunopeptide vaccines in a cost‐effective manner using a plant cell‐suspension culture system.     

Lipid droplets maintain lipid homeostasis during anaphase for efficient cell separation in budding yeast

The neutral lipids steryl ester and triacylglycerol (TAG) are stored in the membrane-bound organelle lipid droplet (LD) in essentially all eukaryotic cells. It is unclear what physiological conditions require the mobilization or storage of these lipids. Here, we study the budding yeast mutant are1Δ are2Δ dga1Δ lro1Δ, which cannot synthesize the neutral lipids and therefore lacks LDs. This quadruple mutant is delayed at cell separation upon release from mitotic arrest. The cells have abnormal septa, unstable septin assembly during cytokinesis, and prolonged exocytosis at the division site at the end of cytokinesis. Lipidomic analysis shows a marked increase of diacylglycerol (DAG) and phosphatidic acid, the precursors for TAG, in the mutant during mitotic exit. The cytokinesis and separation defects are rescued by adding phospholipid precursors or inhibiting fatty acid synthesis, which both reduce DAG levels. Our results suggest that converting excess lipids to neutral lipids for storage during mitotic exit is important for proper execution of cytokinesis and efficient cell separation.     

Sterol methyltransferase is required for optimal mitochondrial function and virulence in Leishmania major

Limited knowledge on the exact functions of ergostane‐based sterols has hampered the application of sterol synthesis inhibitors against trypanosomatid parasites. Sterol methyltransferase (SMT) is directly involved in the synthesis of parasite‐specific C24‐methylated sterols, including ergosterol and 5‐dehydroepisterol. While pharmacological studies hint at its potential as a drug target against trypanosomatids, direct evidence for the cellular function and essentiality of SMT is lacking. Here, we characterized the SMT knockout mutants and their complemented strains in Leishmania major, the causative agent for cutaneous leishmaniasis. Deletion of SMT alleles led to a complete loss of C24‐methylated sterols, which were replaced by cholestane‐based sterols. SMT‐null mutants were fully viable and replicative in culture but showed increased sensitivity to sphingolipid synthesis inhibition. They were not particularly vulnerable to heat, acidic pH, nitrosative or oxidative stress, yet exhibited high mitochondrial membrane potential and increased superoxide generation indicating altered physiology of the mitochondria. Despite possessing high levels of GPI‐anchored glycoconjugates, SMT‐null mutants showed significantly attenuated virulence in mice. In total, our study reveals that the biosynthesis of ergostane‐based sterols is crucial for the proper function of mitochondria and the proliferation of Leishmania parasites in mammals.