Fatigue as an Understudied Barrier to Participation in Life Roles

Fatigue is one of the most burdensome and disabling symptoms in numerous acute and chronic conditions and is associated with reduced participation in all aspects of daily life, for example, parenting, employment, and socialization. Historically, occupational practitioners played key roles in fatigue management by creating and implementing interventions. The American Occupational Therapy Foundation convened a Planning Grant Collective workshop with the goal to develop collaborative research ideas and proposals to advance the understanding and management of fatigue. Participants from occupational therapy and other disciplines, with expertise with fatigue or who were conducting research on fatigue, participated in a 3-day virtual workshop. Four main topics emerged: implementation science, treatment taxonomy, trial design and comparative effectiveness, and phenotyping. This white paper describes the proceedings, summarizes the discussions, and outlines recommendations from the PGC workshop on fatigue.

Mitochondrial division inhibitor 1 (mdivi-1) as a potential pharmacological strategy to prevent vascular restenosis

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Singapore National Medical Research Council

Background

New treatments are needed to prevent post-angioplasty and stent restenosis in coronary artery disease (CAD) and peripheral arterial disease (PAD) patients. Accumulated findings have shown that mitochondrial dysfunction is involved in the pathophysiology mechanisms underlying several cardiovascular conditions, however, in the scenario of vascular remodelling after injury, the role of mitochondrial dynamics is not completely understood.

Purpose

In this study, we investigate the effect of mdivi-1 on neointimal hyperplasia and plaque development in a wire-induced endothelial injury animal model.­

Methods

Using ApoE-/- mice on a background of hyperlipidaemia, we investigated weather in vivo administration of mdivi-1 (1.2mg/kg/d) could reduce atherosclerotic plaque volume, plaque complexity and inflammation in a carotid-wire injury model of neointimal hyperplasia. Also, THP-1 monocytes (T-M) and THP-1-derived Macrophages (T-DM) were stimulated in vitro with LPS + IFN-gamma to induce M1 polarization and then subjected to gene expression and protein analysis in the presence or absence of mdivi-1 (50µM). Transmigration and 3D chemotaxis assays were performed in T-M cells and Human peripheral blood monocytes, to evaluate the effect of mdivi-1 on cell migration in response to M-CSF and MCP-1. Finally, we investigated the effects of Mdivi-1 on mitochondrial respiration using Seahorse assay in T-M and T-DM.

Results

In vivo treatment with mdivi-1 reduced neointimal hyperplasia by 37% when compared to control, and was associated with a significant decrease of vascular smooth muscle cells and macrophages cell numbers, as well as reduction of the pro-inflammatory mediators TNF-α and ICAM-1 in the plaque. In vitro M1 polarization of T-M and T-DM induced both up-regulation and production of pro-inflammatory mediators and mdivi-1 significantly suppressed this effects. In addition, monocyte chemotaxis response to M-CSF and MCP-1 was significantly reduced in the presence of mdivi-1. Lastly, mdivi-1 reduced oxygen consumption rate in T-M and T-DM, and prevented M1-cell polarization.

Conclusions

We show that mdivi-1 significantly reduces vessel wall thickness, neointimal hyperplasia, monocyte recruitment, and inflammation after vascular endothelial injury, positioning Mdivi-1 as a potential pharmacological strategy to reduce restenosis following angioplasty and stenting in CAD and PAD patients.

Vitronectin is sequestered within human spermatozoa and liberated following the acrosome reaction

Vitronectin plays a role in the regulation of complement and thrombin activities and in cell surface proteolysis. Vitronectin is also an intrinsic protein of human spermatozoa. Vitronectin message has been detected in whole testis poly-A mRNA and localized by in-situ reverse transcription-polymerase chain reaction to spermatocytes. The proportion of spermatozoa that express vitronectin increases following their capacitation. In this study, spermatozoa from a man of proven fertility were probed with an anti-vitronectin monoclonal antibody (VN7) before and after their permeabilization with 0.1% Triton X-100. Of fresh spermatozoa observed by confocal microscopy, 0-8% showed vitronectin staining. However, 75% of those observed displayed vitronectin following permeabilization. Serial confocal sections through the sperm head confirmed the internal localization of vitronectin. The acrosomal status of capacitated spermatozoa that expressed vitronectin was then determined. Dual colour microscopy with rhodamine-conjugated anti-vitronectin antibody and a fluorescein-conjugated antibody directed against CD46 (a complement regulatory protein expressed on the inner acrosomal membrane) revealed that only acrosome-reacted (CD46-positive) spermatozoa displayed vitronectin. Two populations of these spermatozoa were observed. Fifty-seven of 260 (22%) were CD46-positive/vitronectin-positive and 72 of 260 (28%) were CD46-positive/vitronectin-negative. No spermatozoa were CD46-negative/vitronectin-positive. These results confirm that vitronectin is released from a sequestered location within the spermatozoon following the acrosome reaction.

Structural requirements for the neutralization of heparin-like saccharides by complement S protein/vitronectin

S protein, a major inhibitor of the assembly of the membrane attack complex of complement, has recently been shown to be identical to the serum spreading factor vitronectin. It also neutralizes the anticoagulant activities of heparin. We have studied the structural requirements for the heparin neutralizing properties of S protein/vitronectin using heparin, heparan sulfate, and heparin oligosaccharides with well defined anticoagulant specificities. The abilities of heparin fractions, Mr 7,800-18,800, with high affinity for antithrombin, and of the International Heparin Standard, to accelerate the inactivation of thrombin and Factor Xa by antithrombin were readily neutralized by S protein/vitronectin. Binding and neutralization of heparin by S protein/vitronectin was inhibited by heparin with low affinity for antithrombin, indicating that S protein/vitronectin can interact with a region on the heparin chain that might serve as a proteinase binding site. S protein/vitronectin efficiently neutralized oligosaccharides of Mr 2,400-7,200, unlike the two other physiologically occurring heparin neutralizing proteins histidine-rich glycoprotein and platelet factor 4. Furthermore, S protein/vitronectin neutralized the anti-Factor Xa activity of a synthetic pentasaccharide comprising the antithrombin-binding sequence of heparin. High molar excess of a synthetic tridecapeptide corresponding to part (amino acids 374-359) of the proposed glycosaminoglycan binding domain of S protein/vitronectin neutralized high affinity heparin and some oligosaccharides, but failed to neutralize the synthetic antithrombin-binding pentasaccharide. Like platelet factor 4, but unlike histidine-rich glycoprotein, S protein/vitronectin readily neutralized the anticoagulant activities of heparan sulfate of Mr approximately 20,000. These findings suggest that S protein/vitronectin may interact through its glycosaminoglycan binding domain(s) with various functional domains of the heparin (heparan sulfate) molecule, including the antithrombin-binding pentasaccharide sequence. Furthermore, the results suggest that S protein/vitronectin may be a physiologically important modulator of the anticoagulant activity of heparin-like material on or near the vascular endothelium.

Photoaffinity labeling of the N-formyl peptide receptor of human polymorphonuclear leukocytes

Quantitative analysis of ligand-occupied receptor interactions with elements of the cytoskeleton and with intracellular compartments requires a sensitive and simple method of identifying the receptor-ligand complex in living cells. Toward this goal, we have prepared a photoactivatable arylazide derivative of the chemotactic peptide N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys, which can be radiolabeled to high specific activity with 125I. This derivative was biologically active as judged by its ability to elicit superoxide anion production by human PMNL at nanomolar concentrations (ED50 approximately 0.7 nM). When incubated at 0 degree C with whole PMNL, radioactive ligand became specifically and saturably associated with a 60-70,000-dalton species (as assessed by SDS-PAGE) after exposure to UV light. Addition of 10-100-fold excess of unlabeled parent or unlabeled azidopeptide derivative completely blocked uptake into this species. Approximately 20-40% of the available surface receptor-binding sites were covalently labeled under these conditions. Subcellular fractionation of the labeled cells on sucrose gradients after homogenization showed that the labeled species was primarily associated with plasma membrane-rich fractions. The labeled receptor could be completely solubilized with Triton X-100 in a form which eluted as a single species with a Stoke's radius of less than 50 A on Sepharose 4B columns. In addition, the solubilized receptor-ligand complex bound specifically to wheat germ agglutinin, indicating that it is probably a glycoprotein. The ability to label the receptor in living PMNL with a high efficiency should facilitate the study of receptor dynamics and receptor physiochemical properties in this system.

Surface localization of apolipoprotein AII in lipoprotein-complexes

Lipoprotein particles reconstituted from the apolipoprotein AII (apo AII) component of human serum high density lipoprotein, phosphatidylcholine and lysophosphatidylcholine were covalently linked to the imidoester groups of a polystyrene residue. Apo AII was proteolytically digested with thermolysin after delipidation. The covalently bound peptides remaining at the resin were cleaved and separated by combined two-dimensional electrophoresis/chromatography. The peptides were isolated, hydrolyzed and their amino acid composition determined. They were assigned to the apo AII sequence. Since the imidoester groups on the surface of the resin carrier cannot react with buried lysine residues, this method gives strong chemical evidence for the spreading of the apo AII polypeptide chain over the surface of the lipoprotein particle, as far as the sequence carrying lysine residues between residue 22 and 55 of each symmetrical half is concerned.

Conformational analysis of serum apolipoprotein AII in lipoprotein complexes with bifunctional crosslinking reagents

Apolipoprotein AII isolated from human serum high density lipoproteins was recombined with phosphatidylcholine to yield homogeneous particles of 80-120 A diameter. The radioactive bifunctional crosslinkers dimethyl [1,1'-14C]suberimidate and dimethyl 4,4'-dithiobis([1-14C]butyrimidate) were reacted with these particles. The kinetics of the reactions and the localisation of the crosslinked lysines of the polypeptide chains were determined. Thermolysin hydrolysis followed by two-dimensional separation of the peptides and isolation of the mono- and bifunctionally modified peptides allowed the assignment of the crosslinked peptides of the apoprotein AII seqeunce. The crosslinking pattern indicates a close-neighbour relationship (13-15 A) of the peptide chains between amino acid residues 3, 23, 46 and 55 of the symmetrical halves of the apo AII molecule. A reconstruction of the secondary structure of Apo AII in the lipoprotein complex on the basis of theoretical calculations is given and correlated with the chemical data.