Browsing by Subject "Erythropoietin"

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    Design, selection, and development of cyclic peptide ligands for human erythropoietin.
    (Journal of chromatography. A, 2017-06) Kish, William S; Sachi, Hiroyuki; Naik, Amith D; Roach, Matthew K; Bobay, Benjamin G; Blackburn, Robert K; Menegatti, Stefano; Carbonell, Ruben G
    This work presents the selection and characterization of erythropoietin (EPO)-binding cyclic peptide ligands. The sequences were selected by screening a focused library of cyclic depsipeptides cyclo[(Nα-Ac)Dap(A)-X1-X6-AE], whose structure and amino acid compositions were tailored to mimic the EPO receptor. The sequences identified through library screening were synthesized on chromatographic resin and characterized via binding-and-elution studies against EPO to select a pool of candidate ligands. Sequences with higher hydrophobicity consistently showed stronger binding to EPO, with the exception of FSLLSH, which was noted for its lower hydrophobicity and high EPO binding. Mutagenesis studies performed on FSLLSH with natural and non-natural amino acid substitutions led to the identification of critical EPO-binding determinants, and the discovery of new peptide ligands. In particular, histidine-scanning mutagenesis performed on three lead sequences yielded the discovery of variants whose EPO-binding is more pH-sensitive, which facilitates EPO recovery. Selected ligands were studied to correlate the elution yield to the salinity of the binding buffer and the elution pH. Elution yields were consistently higher when EPO binding was performed at low ionic strength. The crystal structures of lead cyclic peptides were docked in silico against EPO to estimate the binding affinity in solution. Isotherm adsorption studies performed on FSLLSH indicated that the cyclic version of the ligand (KD=0.46μM) has a higher affinity for EPO than its corresponding linear variant (KD=1.44μM). Collectively, these studies set the stage for use of the cyclic peptide ligands as EPO purification and detection tools.
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    Mitochondrial Quality Control as a Therapeutic Target.
    (Pharmacol Rev, 2016-01) Suliman, Hagir B; Piantadosi, Claude A
    In addition to oxidative phosphorylation (OXPHOS), mitochondria perform other functions such as heme biosynthesis and oxygen sensing and mediate calcium homeostasis, cell growth, and cell death. They participate in cell communication and regulation of inflammation and are important considerations in aging, drug toxicity, and pathogenesis. The cell's capacity to maintain its mitochondria involves intramitochondrial processes, such as heme and protein turnover, and those involving entire organelles, such as fusion, fission, selective mitochondrial macroautophagy (mitophagy), and mitochondrial biogenesis. The integration of these processes exemplifies mitochondrial quality control (QC), which is also important in cellular disorders ranging from primary mitochondrial genetic diseases to those that involve mitochondria secondarily, such as neurodegenerative, cardiovascular, inflammatory, and metabolic syndromes. Consequently, mitochondrial biology represents a potentially useful, but relatively unexploited area of therapeutic innovation. In patients with genetic OXPHOS disorders, the largest group of inborn errors of metabolism, effective therapies, apart from symptomatic and nutritional measures, are largely lacking. Moreover, the genetic and biochemical heterogeneity of these states is remarkably similar to those of certain acquired diseases characterized by metabolic and oxidative stress and displaying wide variability. This biologic variability reflects cell-specific and repair processes that complicate rational pharmacological approaches to both primary and secondary mitochondrial disorders. However, emerging concepts of mitochondrial turnover and dynamics along with new mitochondrial disease models are providing opportunities to develop and evaluate mitochondrial QC-based therapies. The goals of such therapies extend beyond amelioration of energy insufficiency and tissue loss and entail cell repair, cell replacement, and the prevention of fibrosis. This review summarizes current concepts of mitochondria as disease elements and outlines novel strategies to address mitochondrial dysfunction through the stimulation of mitochondrial biogenesis and quality control.
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    Targeting Treatments to Improve Cognitive Function in Mood Disorder: Suggestions From Trials Using Erythropoietin.
    (The Journal of clinical psychiatry, 2016-12) Miskowiak, Kamilla Woznica; Rush, A John; Gerds, Thomas A; Vinberg, Maj; Kessing, Lars V

    Objective

    There is no established efficacious treatment for cognitive dysfunction in unipolar and bipolar disorder. This may be partially due to lack of consensus regarding the need to screen for cognitive impairment in cognition trials or which screening criteria to use. We have demonstrated in 2 randomized placebo-controlled trials that 8 weeks of erythropoietin (EPO) treatment has beneficial effects on verbal memory across unipolar and bipolar disorder, with 58% of EPO-treated patients displaying a clinically relevant memory improvement as compared to 15% of those treated with placebo.

    Methods

    We reassessed the data from our 2 EPO trials conducted between September 2009 and October 2012 to determine whether objective performance-based memory impairment or subjective self-rated cognitive impairment at baseline was related to the effect of EPO on cognitive function as assessed by Rey Auditory Verbal Learning Test (RAVLT) total recall with multiple logistic regression adjusted for diagnosis, age, gender, symptom severity, and education levels.

    Results

    We included 79 patients with an ICD-10 diagnosis of unipolar or bipolar disorder, of whom 39 received EPO and 40 received placebo (saline). For EPO-treated patients with objective memory dysfunction at baseline (n = 16) (defined as RAVLT total recall ≤ 43), the odds of a clinically relevant memory improvement were increased by a factor of 290.6 (95% CI, 2.7-31,316.4; P = .02) compared to patients with no baseline impairment (n = 23). Subjective cognitive complaints (measured with the Cognitive and Physical Functioning Questionnaire) and longer illness duration were associated with small increases in patients' chances of treatment efficacy on memory (53% and 16% increase, respectively; P ≤ .04). Diagnosis, gender, age, baseline depression severity, and number of mood episodes did not significantly change the chances of EPO treatment success (P ≥ .06). In the placebo-treated group, the odds of memory improvement were not significantly different for patients with or without objectively defined memory dysfunction (P ≥ .59) or subjective complaints at baseline (P ≥ .06).

    Conclusions

    Baseline objectively assessed memory impairments and-to a lesser degree-subjective cognitive complaints increased the chances of treatment efficacy on cognition in unipolar and bipolar disorder.

    Trial registration

    ClinicalTrials.gov identifier: NCT00916552.