Glial Hsp70 Protects K+ Homeostasis in the Drosophila Brain during Repetitive Anoxic Depolarization

Neural tissue is particularly vulnerable to metabolic stress and loss of ion homeostasis. Repetitive stress generally leads to more permanent dysfunction but the mechanisms underlying this progression are poorly understood. We investigated the effects of energetic compromise in Drosophila by targeting the Na+/K+-ATPase. Acute ouabain treatment of intact flies resulted in subsequent repetitive comas that led to death and were associated with transient loss of K+ homeostasis in the brain. Heat shock pre-conditioned flies were resistant to ouabain treatment. To control the timing of repeated loss of ion homeostasis we subjected flies to repetitive anoxia while recording extracellular [K+] in the brain. We show that targeted expression of the chaperone protein Hsp70 in glial cells delays a permanent loss of ion homeostasis associated with repetitive anoxic stress and suggest that this is a useful model for investigating molecular mechanisms of neuroprotection

L-Glutamine therapy reduces endothelial adhesion of sickle red blood cells to human umbilical vein endothelial cells

BACKGROUND: We have previously demonstrated that therapy with orally administered L-glutamine improves nicotinamide adenosine dinucleotide (NAD) redox potential of sickle red blood cells (RBC). On further analysis of L-glutamine therapy for sickle cell anemia patients, the effect of L-glutamine on adhesion of sickle RBC to human umbilical vein endothelial cells (HUVEC) was examined. METHODS: The first part of the experiment was conducted with the blood samples of the 5 adult sickle cell anemia patients who had been on L-glutamine therapy for at least 4 weeks on a dosage of 30 grams per day compared to those of patient control group. In the second part of the experiment 6 patients with sickle cell anemia were studied longitudinally. Five of these patients were treated with oral L-glutamine 30 grams daily and one was observed without treatment as the control. t-test and paired t-test were used for determination of statistical significance in cross-sectional and longitudinal studies respectively. RESULTS: In the first study, the mean adhesion to endothelial cells with the autologous plasma incubated cells were 0.97 ± 0.45 for the treated group and 1.91 ± 0.53 for the nontreated group (p < 0.02). Similarly with lipopolysaccharide (LPS) incubated cells the mean adhesion to endothelial cells were 1.39 ± 0.33 for the treated group and 2.80 ± 0.47 for the untreated group (p < 0.001). With the longitudinal experiment, mean decrease in the adhesion to endothelial cells was 1.13 ± 0.21 (p < 0.001) for the 5 treated patients whereas the control patient had slight increase in the adhesion to endothelial cells. CONCLUSION: In these studies, oral L-glutamine administration consistently resulted in improvement of sickle RBC adhesion to HUVEC. These data suggest positive physiological effects of L-glutamine in sickle cell disease

Dual‐drug delivery using dextran‐functionalized nanoparticles targeting cardiac fibroblasts for cellular reprogramming

The inability of the heart to recover from an ischemic insult leads to the formation of fibrotic scar tissue and heart failure. From the therapeutic strategies under investigation, cardiac regeneration holds the promise of restoring the full functionality of a damaged heart. Taking into consideration the presence of vast numbers of fibroblasts and myofibroblasts in the injured heart, direct fibroblast reprogramming into cardiomyocytes using small drug molecules is an attractive therapeutic option to replenish the lost cardiomyocytes. Here, a spermine-acetalated dextran-based functional nanoparticle is developed for pH-triggered drug delivery of two poorly water soluble small molecules, CHIR99021 and SB431542, both capable of increasing the efficiency of direct reprogramming of fibroblast into cardiomyocytes. Upon functionalization with polyethylene glycol and atrial natriuretic peptide, the biocompatibility of the nanosystem is improved, and the cellular interactions with the cardiac nonmyocytes are specifically augmented. The dual delivery of the compounds is verified in vitro, and the compounds exerted concomitantly anticipate biological effects by stabilizing β-catenin (CHIR99021) and by preventing translocation of Smad3 to the nucleus of (myo)fibroblasts (SB431542). These observations highlight the potential of this nanoparticle-based system toward improved drug delivery and efficient direct reprogramming of fibroblasts into cardiomyocyte-like cells, and thus, potential cardiac regeneration therapy.Peer reviewe