Parathyroid hormone-related protein is reduced in severe chronic heart failure

In the cardiovascular system, parathyroid hormone-related peptide (PTHrP) is expressed in various cells such as cardiac vascular smooth muscle cells, coronary endothelial cells and cardiomyocytes and acts as an autocrine/paracrine substance. We compared PTHrP levels in 35 consecutive patients with severe CHF (33 male, mean age 66.2 +/- 8.9 years) with 26 normal controls (24 male, mean age 63.1 +/- 8.6 years). PTHrP levels were reduced in severe CHF patients (11.10 +/- 1.37 fmol/ml) compared with the controls (20.62 +/- 3.30 fmol/ml, p = 0.005). PTHrP values decreased as a function of New York Heart Association classification. These results suggest that PTHrP levels decrease in proportion to the severity of heart failure and could potentially be used to monitor progression of disease non-invasively.     

Common Players in Mitochondria Biogenesis and Neuronal Protection Against Stress-Induced Apoptosis

Mitochondria biogenesis is a fundamental process for the organization and normal function of all cells. Since the majority of mitochondrial proteins are synthesized in the cytosol, protein import is the major mechanism for mitochondria biogenesis. We describe the different pathways that ensure correct targeting and intra mitochondrial sorting of mitochondrial proteins. The import process of several proteins of the mitochondrial intermembrane space relies on the Mitochondrial Import and Assembly 40 and Essential for respiration and vegetative growth 1 (Erv1) proteins that together constitute the oxidative folding machinery of the mitochondrial intermembrane space. Recent work has implicated the FAD-oxidase protein Erv1 (ad its human homolog Augmenter of Liver Regeneration) as an anti-apoptotic factor in mammalian cells (including neuronal cells) that undergo Reactive Oxygen Species-triggered apoptosis. The different roles of this protein as a key factor in mitochondria biogenesis, iron-sulfur cluster biogenesis and in neuronal protection against apoptosis are discussed.     

A comprehensive evaluation of potential lung function associated genes in the SpiroMeta general population sample

Rationale

Lung function measures are heritable traits that predict population morbidity and mortality and are essential for the diagnosis of chronic obstructive pulmonary disease (COPD). Variations in many genes have been reported to affect these traits, but attempts at replication have provided conflicting results. Recently, we undertook a meta-analysis of Genome Wide Association Study (GWAS) results for lung function measures in 20,288 individuals from the general population (the SpiroMeta consortium).

Objectives

To comprehensively analyse previously reported genetic associations with lung function measures, and to investigate whether single nucleotide polymorphisms (SNPs) in these genomic regions are associated with lung function in a large population sample.

Methods

We analysed association for SNPs tagging 130 genes and 48 intergenic regions (+/−10 kb), after conducting a systematic review of the literature in the PubMed database for genetic association studies reporting lung function associations.

Results

The analysis included 16,936 genotyped and imputed SNPs. No loci showed overall significant association for FEV₁ or FEV₁/FVC traits using a carefully defined significance threshold of 1.3×10⁻⁵. The most significant loci associated with FEV₁ include SNPs tagging MACROD2 (P = 6.81×10⁻⁵), CNTN5 (P = 4.37×10⁻⁴), and TRPV4 (P = 1.58×10⁻³). Among ever-smokers, SERPINA1 showed the most significant association with FEV₁ (P = 8.41×10⁻⁵), followed by PDE4D (P = 1.22×10⁻⁴). The strongest association with FEV₁/FVC ratio was observed with ABCC1 (P = 4.38×10⁻⁴), and ESR1 (P = 5.42×10⁻⁴) among ever-smokers.

Conclusions

Polymorphisms spanning previously associated lung function genes did not show strong evidence for association with lung function measures in the SpiroMeta consortium population. Common SERPINA1 polymorphisms may affect FEV₁ among smokers in the general population.     

Targeting and maturation of Erv1/ALR in the mitochondrial intermembrane space

The interaction of Mia40 with Erv1/ALR is central to the oxidative protein folding in the intermembrane space of mitochondria (IMS) as Erv1/ALR oxidizes reduced Mia40 to restore its functional state. Here we address the role of Mia40 in the import and maturation of Erv1/ALR. The C-terminal FAD-binding domain of Erv1/ALR has an essential role in the import process by creating a transient intermolecular disulfide bond with Mia40. The action of Mia40 is selective for the formation of both intra and intersubunit structural disulfide bonds of Erv1/ALR, but the complete maturation process requires additional binding of FAD. Both of these events must follow a specific sequential order to allow Erv1/ALR to reach the fully functional state, illustrating a new paradigm for protein maturation in the IMS.     

Molecular determinants in TRPV5 channel assembly

The epithelial Ca(2+) channels TRPV5 and TRPV6 mediate the Ca(2+) influx in 1,25-dihydroxyvitamin D(3)-responsive epithelia and are therefore essential in the maintenance of the body Ca(2+) balance. These Ca(2+) channels assemble in (hetero)tetrameric channel complexes with different functional characteristics regarding Ca(2+)-dependent inactivation, ion selectivity, and pharmacological block. Glutathione S-transferase pull-downs and co-immunoprecipitations demonstrated an essential role of the intracellular N- and C-tails in TRPV5 channel assembly by physical interactions between N-N tails, C-C tails, and N-C-tails. Patch clamp analysis in human embryonic kidney (HEK293) cells and (45)Ca(2+) uptake experiments in Xenopus laevis oocytes co-expressing TRPV5 wild-type and truncated proteins indicated that TRPV5 Delta N (deleted N-tail) and TRPV5 Delta C (deleted C-tail) decreased channel activity of wild-type TRPV5 in a dominant-negative manner, whereas TRPV5 Delta N Delta C (deleted N-tail/C-tail) did not affect TRPV5 activity. Oocytes co-expressing wild-type TRPV5 and TRPV5 Delta N or TRPV5 Delta C showed virtually no wild-type TRPV5 expression on the plasma membrane, whereas co-expression of wild-type TRPV5 and TRPV5 Delta N Delta C displayed normal channel surface expression. This indicates that TRPV5 trafficking toward the plasma membrane was disturbed by assembly with TRPV5 Delta N or TRPV5 Delta C but not with TRPV5 Delta N Delta C. TRPV5 channel assembly signals were refined between amino acid positions 64-77 and 596-601 in the N-tail and C-tail, respectively. Pull-down assays and co-immunoprecipitations demonstrated that N- or C-tail mutants lacking these critical assembly domains were unable to interact with tails of TRPV5. In conclusion, two domains in the N-tail (residues 64-77) and C-tail (residues 596-601) of TRPV5 are important for channel subunit assembly, subsequent trafficking of the TRPV5 channel complex to the plasma membrane, and channel activity.     

Tunable silk: using microfluidics to fabricate silk fibers with controllable properties

Despite widespread use of silk, it remains a significant challenge to fabricate fibers with properties similar to native silk. It has recently been recognized that the key to tuning silk fiber properties lies in controlling internal structure of assembled β-sheets. We report an advance in the precise control of silk fiber formation with control of properties via microfluidic solution spinning. We use an experimental approach combined with modeling to accurately predict and independently tune fiber properties including Young's modulus and diameter to customize fibers. This is the first reported microfluidic approach capable of fabricating functional fibers with predictable properties and provides new insight into the structural transformations responsible for the unique properties of silk. Unlike bulk processes, our method facilitates the rapid and inexpensive fabrication of fibers from small volumes (50 μL) that can be characterized to investigate sequence-structure-property relationships to optimize recombinant silk technology to match and exceed natural silk properties.     

Controlled Release of 5-Fluorouracil from Alginate Beads Encapsulated in 3D Printed pH-Responsive Solid Dosage Forms

Three-dimensional printing is being steadily deployed as manufacturing technology for the development of personalized pharmaceutical dosage forms. In the present study, we developed a hollow pH-responsive 3D printed tablet encapsulating drug loaded non-coated and chitosan-coated alginate beads for the targeted colonic delivery of 5-fluorouracil (5-FU). A mixture of Eudragit® L100-55 and Eudragit® S100 was fabricated by means of hot-melt extrusion (HME) and the produced filaments were printed utilizing a fused deposition modeling (FDM) 3D printer to form the pH-responsive layer of the tablet with the rest comprising of a water-insoluble poly-lactic acid (PLA) layer. The filaments and alginate particles were characterized for their physicochemical properties (thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction), their surface topography was visualized by scanning electron microscopy and the filaments’ mechanical properties were assessed by instrumented indentation testing and tensile testing. The optimized filament formulation was 3D printed and the structural integrity of the hollow tablet in increasing pH media (pH 1.2 to pH 7.4) was assessed by means of time-lapsed microfocus computed tomography (μCT). In vitro release studies demonstrated controlled release of 5-FU from the alginate beads encapsulated within the hollow pH-sensitive tablet matrix at pH values corresponding to the colonic environment (pH 7.4). The present study highlights the potential of additive manufacturing in fabricating controlled-release dosage forms rendering them pertinent formulations for further in vivo evaluation.