Cdk12 maintains the integrity of adult axons by suppressing actin remodeling

The role of cyclin-dependent kinases (CDKs) that are ubiquitously expressed in the adult nervous system remains unclear. Cdk12 is enriched in terminally differentiated neurons where its conical role in the cell cycle progression is redundant. We find that in adult neurons Cdk12 acts a negative regulator of actin formation, mitochondrial dynamics and neuronal physiology. Cdk12 maintains the size of the axon at sites proximal to the cell body through the transcription of homeostatic enzymes in the 1-carbon by folate pathway which utilize the amino acid homocysteine. Loss of Cdk12 leads to elevated homocysteine and in turn leads to uncontrolled F-actin formation and axonal swelling. Actin remodeling further induces Drp1-dependent fission of mitochondria and the breakdown of axon-soma filtration barrier allowing soma restricted cargos to enter the axon. We demonstrate that Cdk12 is also an essential gene for long-term neuronal survival and loss of this gene causes age-dependent neurodegeneration. Hyperhomocysteinemia, actin changes, and mitochondrial fragmentation are associated with several neurodegenerative conditions such as Alzheimer's disease and we provide a candidate molecular pathway to link together such pathological events.

Democratising “Microscopi”: a 3D printed automated XYZT fluorescence imaging system for teaching, outreach and fieldwork

Commercial fluorescence microscope stands and fully automated XYZt fluorescence imaging systems are generally beyond the limited budgets available for teaching and outreach. We have addressed this problem by developing “Microscopi”, an accessible, affordable, DIY automated imaging system that is built from 3D printed and commodity off-the-shelf hardware, including electro-mechanical, computer and optical components. Our design features automated sample navigation and image capture with a simple web-based graphical user interface, accessible with a tablet or other mobile device. The light path can easily be switched between different imaging modalities. The open source Python-based control software allows the hardware to be driven as an integrated imaging system. Furthermore, the microscope is fully customisable, which also enhances its value as a learning tool. Here, we describe the basic design and demonstrate imaging performance for a range of easily sourced specimens.

Democratising "Microscopi": a 3D printed automated XYZT fluorescence imaging system for teaching, outreach and fieldwork

Commercial fluorescence microscope stands and fully automated XYZt fluorescence imaging systems are generally beyond the limited budgets available for teaching and outreach. We have addressed this problem by developing "Microscopi", an accessible, affordable, DIY automated imaging system that is built from 3D printed and commodity off-the-shelf hardware, including electro-mechanical, computer and optical components. Our design features automated sample navigation and image capture with a simple web-based graphical user interface, accessible with a tablet or other mobile device. The light path can easily be switched between different imaging modalities. The open source Python-based control software allows the hardware to be driven as an integrated imaging system. Furthermore, the microscope is fully customisable, which also enhances its value as a learning tool. Here, we describe the basic design and demonstrate imaging performance for a range of easily sourced specimens.

Morbidity and mortality in Danio rerio and Pimephales promelas exposed to antilipidemic drug mixtures (fibrates and statins) during embryogenesis: Comprehensive assessment via ante and post mortem endpoints

Antilipidemic drugs are routinely detected in effluent and surface waters downstream of wastewater treatment plants. A mixture exposure study with nine environmentally relevant antilipidemic drugs was performed with zebrafish (Danio rerio, ZF) and fathead minnow (Pimephales promelas, FHM) embryos to investigate the effects on sensitive embryologic stages. Zebrafish embryos were exposed nominally to: (a) 0.005 μM, (b) 0.05 μM, or (c) 0.5 μM of each drug in the mixture. Fathead minnow embryos were exposed nominally to: (a) 0.0005 μM, (b) 0.005 μM, or (c) 0.05 μM of each drug in the mixture. Several of the individual drug concentrations were within ranges previously found in the environment. Multiple metrics demonstrate that (a) exposure of ZF and FHM embryos to antilipidemic drugs during embryonic development results in lethal and sublethal effects, (b) ZF were more sensitive than FHM based on median lethal concentration (LC₅₀ 0.02 μM and 0.05 μM, respectively), but FHM exhibited more severe abnormal sublethal morphologies than zebrafish embryos, and (c) the sublethal effects differed between the two species. This model identified novel specific endpoints for assessing sensitive, sublethal effects of pharmaceuticals in the environment. Abnormal myofiber birefringence pattern, hemorrhage, and heart rate are not included in standard evaluations but each of these metrics demonstrated a dose-dependent response in this study. Results demonstrate risk to fish development with potential repercussions at the population level, especially if environmental concentrations increase.

Runx1 promotes scar deposition and inhibits myocardial proliferation and survival during zebrafish heart regeneration

Runx1 is a transcription factor that plays a key role in determining the proliferative and differential state of multiple cell types, during both development and adulthood. Here, we report how Runx1 is specifically upregulated at the injury site during zebrafish heart regeneration, and that absence of runx1 results in increased myocardial survival and proliferation, and overall heart regeneration, accompanied by decreased fibrosis. Using single cell sequencing, we found that the wild-type injury site consists of Runx1-positive endocardial cells and thrombocytes that induce expression of smooth muscle and collagen genes. Both these populations cannot be identified in runx1 mutant wounds that contain less collagen and fibrin. The reduction in fibrin in the mutant is further explained by reduced myofibroblast formation and upregulation of components of the fibrin degradation pathway, including plasminogen receptor annexin 2A as well as downregulation of plasminogen activator inhibitor serpine1 in myocardium and endocardium, resulting in increased levels of plasminogen. Our findings suggest that Runx1 controls the regenerative response of multiple cardiac cell types and that targeting Runx1 is a novel therapeutic strategy for inducing endogenous heart repair.

Microscope calibration using laser written fluorescence

There is currently no widely adopted standard for the optical characterization of fluorescence microscopes. We used laser written fluorescence to generate two- and three-dimensional patterns to deliver a quick and quantitative measure of imaging performance. We report on the use of two laser written patterns to measure the lateral resolution, illumination uniformity, lens distortion and color plane alignment using confocal and structured illumination fluorescence microscopes.

Melanoma Inhibition by Anthocyanins Is Associated with the Reduction of Oxidative Stress Biomarkers and Changes in Mitochondrial Membrane Potential

Anthocyanins are water soluble pigments which have been proved to exhibit health benefits. Several studies have investigated their effects on several types of cancer, but little attention has been given to melanoma. The phytochemical content of nine different berry samples was assessed by liquid chromatography followed by electrospray ionization mass spectrometry (LC-ESI⁺-MS). Twenty-six anthocyanins were identified, after a previous C₁₈ Sep-pak clean-up procedure. Chokeberry and red grape anthocyanins rich extracts (C-ARE and RG-ARE) were selected to be tested on normal and melanoma cell lines, due to their different chemical pattern. C-ARE composition consists of cyanidin aglycone glycosylated with different sugars; while RG-ARE contains glucosylated derivatives of five different aglycones. Both C-ARE and RG-ARE anthocyanins reduced proliferation, increased oxidative stress biomarkers and diminished mitochondrial membrane potential in melanoma cells, having no negative influence on normal cells. A synergistic response may be attributed to the five different aglycones present in RG-ARE, which proved to exert greater effects on melanoma cells than the mixture of cyanidin derivatives with different sugars (C-ARE). In conclusion, C-ARE and RG-ARE anthocyanins may inhibit melanoma cell proliferation and increase the level of oxidative stress, with opposite effect on normal cells. Therefore, anthocyanins might be recommended as active ingredients for cosmetic and nutraceutical industry. Graphical Abstract ᅟ.

Covalent assembly of nanoparticles as a peptidase-degradable platform for molecular MRI

Ligand-conjugated microparticles of iron oxide (MPIO) have the potential to provide high sensitivity contrast for molecular magnetic resonance imaging (MRI). However, the accumulation and persistence of non-biodegradable micron-sized particles in liver and spleen precludes their clinical use and limits the translational potential of MPIO-based contrast agents. Here we show that ligand-targeted MPIO derived from multiple iron oxide nanoparticles may be coupled covalently through peptide linkers that are designed to be cleaved by intracellular macrophage proteases. The synthesized particles possess potential characteristics for targeted MRI contrast agents, including high relaxivity, unappreciable sedimentation, clearance from circulation and no overt toxicity. Importantly, we demonstrate that these particles are rapidly degraded both in vitro and in vivo, and that the targeted probes can be used for detection of inflammation in vivo using MRI. This approach provides a platform for molecular MRI contrast agents that is potentially more suitable for translation to humans.

Changes in non-opioid substitution treatment episodes for pharmaceutical opioids and heroin from 2002 to 2011

BACKGROUND

There has been a well-documented increase in the non-medical use of pharmaceutical opioids (PO) worldwide. However, there has been little detailed examination of treatment demand, or the characteristics of those presenting for treatment, particularly for treatments other than opioid substitution.

METHODS

Data from closed drug and alcohol treatment episodes from the Alcohol and Other Drug Treatment Services National Minimum Data Set (AODTS-NMDS, representing non-opioid substitution treatment) in Australia for 2002-2003 to 2010-2011 were examined. In the four jurisdictions where detailed data were available, episodes where heroin was the principal drug of concern were compared to episodes for the four most frequently reported pharmaceutical opioids (morphine, codeine, fentanyl and oxycodone).

RESULTS

In 2002-2003, most (93%) opioid treatment was related to heroin with seven percent of all opioid treatment episodes reporting a PO as the principal drug of concern. In 2010-2011, 20% of all opioid treatment episodes were attributed to POs. Distinct changes over time were observed for different opioids. There was an increase in the average age at the start of treatment for heroin and oxycodone episodes, and a reduction in the proportion of females for codeine episodes, with 67% in 2002-2003 compared with 44% in 2010-2011. Codeine and oxycodone episodes had the lowest current or past injection rates.

CONCLUSIONS

Clear differences were observed over time and between different opioids. Monitoring these emerging patterns will be important to inform treatment needs, particularly in light of different patterns of poly drug use, different routes of administration and changing demographic characteristics.

Molecular magnetic resonance imaging of angiogenesis in vivo using polyvalent cyclic RGD-iron oxide microparticle conjugates

Angiogenesis is an essential component of tumour growth and, consequently, an important target both therapeutically and diagnostically. The cell adhesion molecule α(v)β(3) integrin is a specific marker of angiogenic vessels and the most prevalent vascular integrin that binds the amino acid sequence arginine-glycine-aspartic acid (RGD). Previous studies using RGD-targeted nanoparticles (20-50 nm diameter) of iron oxide (NPIO) for magnetic resonance imaging (MRI) of tumour angiogenesis, have identified a number of limitations, including non-specific extravasation, long blood half-life (reducing specific contrast) and low targeting valency. The aim of this study, therefore, was to determine whether conjugation of a cyclic RGD variant [c(RGDyK)], with enhanced affinity for α(v)β(3), to microparticles of iron oxide (MPIO) would provide a more sensitive contrast agent for imaging of angiogenic tumour vessels. Cyclic RGD [c(RGDyK)] and RAD [c(RADyK)] based peptides were coupled to 2.8 μm MPIO, and binding efficacy tested both in vitro and in vivo. Significantly greater specific binding of c(RGDyK)-MPIO to S-nitroso-n-acetylpenicillamine (SNAP)-stimulated human umbilical vein endothelial cells in vitro than PBS-treated cells was demonstrated under both static (14-fold increase; P < 0.001) and flow (44-fold increase; P < 0.001) conditions. Subsequently, mice bearing subcutaneous colorectal (MC38) or melanoma (B16F10) derived tumours underwent in vivo MRI pre- and post-intravenous administration of c(RGDyK)-MPIO or c(RADyK)-MPIO. A significantly greater volume of MPIO-induced hypointensities were found in c(RGDyK)-MPIO injected compared to c(RADyK)-MPIO injected mice, in both tumour models (P < 0.05). Similarly, administration of c(RGDyK)-MPIO induced a greater reduction in mean tumour T(2)* relaxation times than the control agent in both tumour models (melanoma P < 0.001; colorectal P < 0.0001). Correspondingly, MPIO density per tumour volume assessed immunohistochemically was significantly greater for c(RGDyK)-MPIO than c(RADyK)-MPIO injected animals, in both melanoma (P < 0.05) and colorectal (P < 0.0005) tumours. In both cases, binding of c(RGDyK)-MPIO co-localised with α(v)β(3) expression. Comparison of RGD-targeted and dynamic contrast enhanced (DCE) MRI assessment of tumour perfusion indicated sensitivity to different vascular features. This study demonstrates specific binding of c(RGDyK)-MPIO to α(v)β(3) expressing neo-vessels, with marked and quantifiable contrast and rapid clearance of unbound particles from the blood circulation compared to NPIO. Combination of this molecular MRI approach with conventional DCE MRI will enable integrated molecular, anatomical and perfusion tumour imaging.

Exogenous microparticles of iron oxide bind to activated endothelial cells but, unlike monocytes, do not trigger an endothelial response

Targeting particles to sites of inflammation is of considerable interest for applications relating to molecular imaging and drug delivery. We and others have described micron-sized particles of iron oxide (MPIO) that can be directed using specific ligands (e.g. antibodies, peptides and oligosaccharides) to bind to mediators of vascular inflammation in vivo. Since leukocyte binding to these molecules can induce changes in the target cell, an outstanding question has been whether the binding of imaging particles to these mediators induces biologically significant changes in the endothelial cells, potentially initiating or propagating inflammation. Here, we address these questions by looking for changes in endothelial cells following binding of contrast agent. Specifically, we have quantified calcium flux, rearrangement of the actin cytoskeleton, production of reactive oxygen species (ROS), apoptosis and potential secondary changes, such as changes in gene and protein expression follow binding events to primary endothelial cells in vitro.

Although leukocytes induced changes to endothelial cell function, we did not see any significant changes to endothelial calcium flux, cytoskeletal organisation, production of ROS or induction of apoptosis in response to antibody-MPIO binding. Furthermore, there were no changes to gene expression monitored via real-time RT-PCR or presentation of protein on the cell surface measured using flow cytometry.

Our experiments demonstrate that whilst antibody-targeted microparticles mimic the binding capability of leukocytes to inflamed endothelium, they do not trigger the same cellular responses and do not appear to initiate or compound inflammation. These properties are desirable for targeted therapeutic and diagnostic agents.

Nicotinic acid receptor GPR109A is down-regulated in human macrophage-derived foam cells

Nicotinic acid (NA) regresses atherosclerosis in human imaging studies and reduces atherosclerosis in mice, mediated by myeloid cells, independent of lipoproteins. Since GPR109A is expressed by human monocytes, we hypothesized that NA may drive cholesterol efflux from foam cells. In THP-1 cells NA suppressed LPS-induced mRNA transcription of MCP-1 by 76.6±12.2% (P<0.01) and TNFα by 56.1±11.5% (P<0.01), yet restored LPS-induced suppression of PPARγ transcription by 536.5±46.4% (P<0.001) and its downstream effector CD36 by 116.8±19.8% (P<0.01). Whilst direct PPARγ-agonism promoted cholesterol efflux from THP-1 derived foam cells by 37.7±3.1% (P<0.01) and stimulated transcription of LXRα by 87.9±9.5% (P<0.001) and ABCG1 by 101.2±15.5% (P<0.01), NA showed no effect in foam cells on either cholesterol efflux or key RCT genes transcription. Upon foam cell induction, NA lost its effect on PPARγ and cAMP pathways, since its receptor, GPR109A, was down-regulated by foam cell transformation. This observation was confirmed in explanted human carotid plaques. In conclusion, despite NA's anti-inflammatory effect on human macrophages, it has no effect on foam cells in reverse cholesterol transport; due to GPR109A down-regulation.

A leukocyte-mimetic magnetic resonance imaging contrast agent homes rapidly to activated endothelium and tracks with atherosclerotic lesion macrophage content

OBJECTIVE

Endothelial cell activation is an important mediator of monocyte recruitment to sites of vascular inflammation. We hypothesized that high-affinity dual-ligand microparticles of iron oxide (MPIO), targeted to P-selectin and vascular cell adhesion molecule-1 (PV-MPIO), would identify activated endothelial cells during atherosclerosis progression.

METHODS AND RESULTS

In vivo magnetic resonance imaging in apolipoprotein E-deficient mice showed rapid binding of PV-MPIO to the aortic root, which was maximal 30 minutes post-MPIO injection and maintained at 60 minutes. Minimal binding was observed for control IgG-MPIO. Intensely low magnetic resonance signal areas, corresponding to PV-MPIO binding, were detected early (14 weeks), during foam cell formation. Contrast effects increased at 20 weeks during fibrofatty lesion development (P<0.05), but reduced by 30 weeks (P<0.01). Across all lesion severities, magnetic resonance imaging contrast effects correlated with lesion macrophage area quantified by immunohistochemistry (R=0.53; P<0.01). Near-infrared fluorescently labeled PV-MPIO were shown, by flow cytometry, to bind only activated endothelial cells and not to macrophages. Using en face immunofluorescence, we further demonstrate selective PV-MPIO accumulation at atherosclerosis-susceptible sites, with minimal binding to atherosclerosis-spared regions.

CONCLUSIONS

This high-affinity leukocyte-mimetic magnetic resonance imaging agent reveals endothelial activation. PV-MPIO demonstrate exceptionally rapid in vivo steady state accumulation, providing conspicuous magnetic resonance contrast effects that can be objectively quantified. In atherosclerosis progression, PV-MPIO tracked closely with the burden and distribution of plaque macrophages, not merely plaque size. On a biocompatible platform, this approach has potential for quantitative magnetic resonance imaging of inflammatory disease activity.

Development and application of endothelium-targeted microparticles for molecular magnetic resonance imaging

Molecular imaging of disease states can enhance diagnosis allowing for accurate and more effective treatment. By specifically targeting molecules differentially expressed in disease states, researchers and clinicians have a means of disease characterization at a cellular or tissue level. Targeted micron-sized particles of iron oxide (MPIO) have been used as molecule-specific contrast agents for use with magnetic resonance imaging (MRI), and early evidence suggests they may be suitable for use with other imaging modalities. Targeting of MPIO to markers of disease is commonly achieved through the covalent attachment of antibodies to the surface of the particles, providing an imaging agent that is both highly specific and which binds with high affinity. When comparing micron-sized particles with nanometre-sized particles, the former provide substantial signal dropout in MRI and confer the sensitivity to detect low levels of target. Furthermore, larger particles appear to bind to targets more potently than smaller particles. Animal models have also demonstrated favorable blood clearance characteristics of MPIO, which are important in achieving favorable signal over background and to attain clearance and disposal. Although the current generation of commercially available MPIO are not suitable for administration into humans, future work may focus on the development of biodegradable and nonimmunogenic MPIO that may allow the use of these imaging agents in a clinical setting.

Subunit composition of AMPK trimers present in the cytokinetic apparatus: Implications for drug target identification

AMP-activated protein kinase has been shown to be a key regulator of energy homeostasis; it has also been identified as a tumor suppressor and is required for correct cell division and chromosome segregation during mitosis. The enzyme is a heterotrimer, with each subunit having more than one isoform, each encoded by a separate gene (two α, two β and three γ isoforms). In human endothelial cells, the activated kinase subunit of AMPK in the cytokinetic apparatus is α2, the minority α subunit, which co-localizes with β2 and γ2. This is the first demonstration of a trimeric complex of AMPK containing the γ2 regulatory subunit becoming selectively activated and being linked to mitotic processes. We also show that α1 and γ1, the predominant AMPK subunits, are almost exclusively localized in the cytoskeleton, while α2 and γ2 are present in all subcellular fractions, including the nuclei. These data suggest that pharmacological interventions targeted to specific AMPK subunit isoforms have the potential to modify selective functions of AMPK.

Anti-inflammatory effects of nicotinic acid in human monocytes are mediated by GPR109A dependent mechanisms

OBJECTIVE

Nicotinic acid (NA) treatment has been associated with benefits in atherosclerosis that are usually attributed to effects on plasma lipoproteins. The NA receptor GPR109A is expressed in monocytes and macrophages, suggesting a possible additional role for NA in modulating function of these immune cells. We hypothesize that NA has the potential to act directly on monocytes to alter mediators of inflammation that may contribute to its antiatherogenic effects in vivo.

METHODS AND RESULTS

In human monocytes activated by Toll-like receptor (TLR)-4 agonist lipopolysaccharide, NA reduced secretion of proinflammatory mediators: TNF-α (by 49.2±4.5%); interleukin-6 (by 56.2±2.8%), and monocyte chemoattractant protein-1 (by 43.2±3.1%) (P<0.01). In TLR2 agonist, heat-killed Listeria monocytogenes-activated human monocytes, NA reduced secretion of TNF-α (by 48.6±7.1%), interleukin-6 (by 60.9±1.6%), and monocyte chemoattractant protein-1 (by 59.3±5.3%) (P<0.01; n=7). Knockdown of GPR109A by siRNA resulted in a loss of this anti-inflammatory effect in THP-1 monocytes. However, inhibition of prostaglandin D2 receptor by MK0524 or COX2 by NS398 did not alter the anti-inflammatory effects of NA observed in activated human monocytes. Preincubation of THP-1 monocytes with NA 0.1 mmol/L reduced phosphorylated IKKβ by 42±2% (P<0.001) IKB-α by 54±14% (P<0.01). Accumulation of nuclear p65 NF-κB in response to lipopolysaccharide treatment was also profoundly inhibited, by 89±1.3% (n=4; P<0.01). NA potently inhibited monocyte adhesion to activated HUVEC, and VCAM, mediated by the integrin, very late antigen 4. Monocyte chemotaxis was also significantly reduced (by 45.7±1.2%; P<0.001).

CONCLUSION

NA displays a range of effects that are lipoprotein-independent and potentially antiatherogenic. These effects are mediated by GPR109A and are independent of prostaglandin pathways. They suggest a rationale for treatment with NA that is not dependent on levels of plasma cholesterol and possible applications beyond the treatment of dyslipidemia.

Molecular imaging with optical coherence tomography using ligand-conjugated microparticles that detect activated endothelial cells: rational design through target quantification

Objectives

Optical coherence tomography (OCT) is a high resolution imaging technique used to assess superficial atherosclerotic plaque morphology. Utility of OCT may be enhanced by contrast agents targeting molecular mediators of inflammation.

Methods and results

Microparticles of iron oxide (MPIO; 1 and 4.5 μm diameter) in suspension were visualized and accurately quantified using a clinical optical coherence tomography system. Bound to PECAM-1 on a plane of cultured endothelial cells under static conditions, 1 μm MPIO were also readily detected by OCT. To design a molecular contrast probe that would bind activated endothelium under conditions of shear stress, we quantified the expression (basal vs. TNF-activated; molecules μm⁻²) of VCAM-1 (not detected vs. 16 ± 1); PECAM-1 (132 ± 6 vs. 198 ± 10) and E-selectin (not detected vs. 46 ± 0.6) using quantitative flow cytometry. We then compared the retention of antibody-conjugated MPIO targeting each of these molecules plus a combined VCAM-1 and E-selectin (E + V) probe across a range of physiologically relevant shear stresses. E + V MPIO were consistently retained with highest efficiency (P < 0.001) and at a density that provided conspicuous contrast effects on OCT pullback.

Conclusion

Microparticles of iron oxide were detectable using a clinical OCT system. Assessment of binding under flow conditions recommended an approach that targeted both E-selectin and VCAM-1. Bound to HUVEC under conditions of flow, targeted 1 μm E + V MPIO were readily identified on OCT pullback. Molecular imaging with OCT may be feasible in vivo using antibody targeted MPIO.

How effective is endovascular intracranial revascularization in stroke prevention? Results from Borgess Medical Center Intracranial Revascularization Registry

BACKGROUND AND PURPOSE

The WASID study established the risk of subsequent ischemic stroke at 1 year in subjects with symptomatic intracranial atherosclerotic stenosis (70%-99%) at 18%. The efficacy of different methods of endovascular revascularization in stroke prevention still has not been established. We compared the stroke rate in our registry at 1 year following intervention with the WASID results to identify which method, if any, provides the most benefit in stroke prevention. This result from the BMC-IRR follows a previously published article comparing stent placement and angioplasty outcomes.

MATERIALS AND METHODS

We maintained a nonrandomized single-center single-operator registry of consecutive symptomatic patients who underwent endovascular intracranial revascularization. Data were collected prospectively and retrospectively and analyzed retrospectively. Patients were treated with angioplasty, BMS, or self-expanding WS. To make our data comparable with that in the WASID study, we selected patients with a single lesion of 50%-99% stenosis undergoing a single intervention. Data was collected on patients until symptom recurrence, repeat intervention, or 1 year postintervention, whichever occurred first.

RESULTS

We found that 115 patients fit the inclusion criteria, with 38 angioplasty, 28 BMS, and 49 WS cases. For patients with 70%-99% stenosis, the overall probability of stroke at 1 year postintervention was 19.3%. The overall stroke probability per device, independent of clinical presentation, was 12.5% for angioplasty, 20.2% for BMS, and 24.1% for WS.

CONCLUSIONS

Compared with the WASID data, angioplasty appears to have a lower stroke rate after 1 year than medical therapy alone. However, neither stent-placement arm compared favorably with the WASID results.

Bulk and adsorbed monolayer phase behavior of binary mixtures of undecanoic acid and undecylamine: catanionic monolayers

Differential scanning calorimetry (DSC) and X-ray powder diffraction (PXRD) have been used to determine the phase behavior of the binary mixtures of undecanoic acid (A) and undecylamine (B) in the bulk. In addition, we report DSC data that indicates very similar behavior for the solid monolayers of these materials adsorbed on the surface of graphite. The two species are found to form a series of stoichiometric complexes of the type AB, A(2)B, and A(3)B on the acid rich side of the phase diagram. Interestingly, no similar series of complexes is evident on the amine rich side. As a result of this complexation, the solid monolayers of the binary mixtures exhibit a very pronounced enhancement in stability relative to the pure adsorbates.

In vivo quantification of VCAM-1 expression in renal ischemia reperfusion injury using non-invasive magnetic resonance molecular imaging

Rationale and Objective

Vascular cell adhesion molecule-1 (VCAM-1) is upregulated in ischemia reperfusion injury (IRI), persisting after restoration of blood flow. We hypothesized that microparticles of iron oxide targeting VCAM-1 (VCAM-MPIO) would depict “ischemic memory” and enable in vivo assessment of VCAM-1 expression.

Methodology and Findings

Mice subject to unilateral, transient (30 minutes) renal ischemia and subsequent reperfusion received intravenous VCAM-MPIO (4.5 mg iron/kg body weight). Contrast agent bound rapidly (<30 minutes) in IRI-kidneys and appeared as intensely low signal areas by MRI in vivo. Automated segmentation and quantification yielded MPIO contrast volumes of 5991±354×10⁶ µm³ in IRI vs. 87±7×10⁶ µm³ in kidneys with no surgical intervention (P<0.001); 90±8×10⁶ µm³ in IRI kidneys exposed to control (IgG-MPIO) and 625±80×10⁶ µm³, in IRI kidneys pre-treated with a blocking dose of VCAM-1 antibody (P<0.001). In keeping with quantitative MRI data, VCAM-1 mRNA expression in IRI was 65-fold higher than in kidneys without surgical intervention (3.06±0.63 vs. 0.05±0.02, P<0.001). Indeed VCAM-1 mRNA expression and VCAM-MPIO contrast volume were highly correlated (R² = 0.901, P<0.01), indicating that quantification of contrast volume reflected renal VCAM-1 transcription. Serial imaging showed VCAM-MPIO accumulation at target within 30 minutes, persisting for ≥90 minutes, while unbound VCAM-MPIO was cleared rapidly from blood, with sequestration by mac-3 positive Kupffer cells in the liver and monocyte/macrophages in the spleen.

Conclusions

(1) VCAM-MPIO detected VCAM-1 expression and defined its 3-dimensional distribution, revealing “ischemic memory” in renal IRI; (2) automated volumetric quantification of VCAM-MPIO accurately reflected tissue levels of VCAM-1 mRNA; and (3) VCAM-MPIO bound rapidly to target with active sequestration of unbound MPIO in the liver and spleen.

Target: ligand interactions of the vascular endothelium. Implications for molecular imaging in inflammation

Molecular imaging refers to the non-invasive visualisation of biological processes at the molecular and cellular levels within a living organism, and offers a wide range of potential benefits to both clinical medicine and research into novel therapeutic agents. Inflammation plays an important role in a wide variety of pathological processes and imaging the molecular and cellular machinery that underlies chronic inflammation is attractive and feasible. In this review, we present an overview of molecular imaging of inflammation. We start by characterising molecular and cellular events in early inflammation, identifying current and potential future imaging targets. We focus on the imaging of endothelial cells, which mediate the important first steps in inflammation in any tissue, are readily accessible to imaging probes and which present an approach that can be applied across multiple modalities. We then review the generic requirements for imaging contrast agents and focus on the important considerations in respect of ligands, ligand-target interactions and contrast vehicles. We aim to provide an integrated view of current progress with a focus on promising recent developments in experimental and translational molecular imaging.

Altered intra-nuclear organisation of heterochromatin and genes in ICF syndrome

The ICF syndrome is a rare autosomal recessive disorder, the most common symptoms of which are immunodeficiency, facial anomalies and cytogenetic defects involving decondensation and instability of chromosome 1, 9 and 16 centromeric regions. ICF is also characterised by significant hypomethylation of the classical satellite DNA, the major constituent of the juxtacentromeric heterochromatin. Here we report the first attempt at analysing some of the defining genetic and epigenetic changes of this syndrome from a nuclear architecture perspective. In particular, we have compared in ICF (Type 1 and Type 2) and controls the large-scale organisation of chromosome 1 and 16 juxtacentromeric heterochromatic regions, their intra-nuclear positioning, and co-localisation with five specific genes (BTG2, CNN3, ID3, RGS1, F13A1), on which we have concurrently conducted expression and methylation analysis. Our investigations, carried out by a combination of molecular and cytological techniques, demonstrate the existence of specific and quantifiable differences in the genomic and nuclear organisation of the juxtacentromeric heterochromatin in ICF. DNA hypomethylation, previously reported to correlate with the decondensation of centromeric regions in metaphase described in these patients, appears also to correlate with the heterochromatin spatial configuration in interphase. Finally, our findings on the relative positioning of hypomethylated satellite sequences and abnormally expressed genes suggest a connection between disruption of long-range gene-heterochromatin associations and some of the changes in gene expression in ICF. Beyond its relevance to the ICF syndrome, by addressing fundamental principles of chromosome functional organisation within the cell nucleus, this work aims to contribute to the current debate on the epigenetic impact of nuclear architecture in development and disease.

Na(+)-K(+)-ATPase and Ca(2+) clearance proteins in smooth muscle: a functional unit

The Na(+)-K(+)-ATPase (NKA) can affect intracellular Ca(2+) concentration regulation via coupling to the Na(+)-Ca(2+) exchanger and may be important in myogenic tone. We previously reported that in mice carrying a transgene for the NKA alpha(2)-isoform in smooth muscle (alpha(2sm+)), the alpha(2)-isoform protein as well as the alpha(1)-isoform (not contained in the transgene) increased to similar degrees (2-7-fold). Aortas from alpha(2sm+) mice relaxed faster from a KCl-induced contraction, hypothesized to be related to more rapid Ca(2+) clearance. To elucidate the mechanisms underlying this faster relaxation, we therefore measured the expression and distribution of proteins involved in Ca(2+) clearance. Na(+)-Ca(2+) exchanger, sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA), and plasma membrane Ca(2+)-ATPase (PMCA) proteins were all elevated up to approximately fivefold, whereas actin, myosin light chain, and calponin proteins were not changed in smooth muscle from alpha(2sm+) mice. Interestingly, the corresponding Ca(2+) clearance mRNA levels were unchanged. Immunocytochemical data indicate that the Ca(2+) clearance proteins are distributed similarly in wild-type and alpha(2sm+) aorta cells. In studies measuring relaxation half-times from a KCl-induced contraction in the presence of pharmacological inhibitors of SERCA and PMCA, we estimated that together these proteins were responsible for approximately 60-70% of relaxation in aorta. Moreover, the percent contribution of SERCA and PMCA to relaxation rates in alpha(2sm+) aorta was not significantly different from that in wild-type aorta. The coordinate expressions of NKA and Ca(2+) clearance proteins without change in the relative contributions of each individual protein to smooth muscle function suggest that NKA may be but one component of a larger functional Ca(2+) clearance system.

Fluorescence in situ hybridization (FISH) for genomic investigations in rat

This chapter concentrates on the use of fluorescence in situ hybridization (FISH) for genomic investigations in the laboratory rat (Rattus norvegicus). The selection of protocols included in the chapter has been inspired by a comprehensive range of previously published molecular cytogenetic studies on this model organism, reporting examples of how FISH can be applied for diverse investigative purposes, varying from comparative gene mapping to studies of chromosome structure and genome evolution, to characterization of chromosomes aberrations as well as transgenic insertions. The protocols, which include techniques for the preparation of mitotic chromosomes and DNA fibers from short-term cell cultures, have been gathered through the years and repeatedly tested in our laboratory, and all together aim at providing sufficient experimental versatility to cover a broad range of cytogenetic and cytogenomic applications.

HAC stability in murine cells is influenced by nuclear localization and chromatin organization

BACKGROUND

Human artificial chromosomes (HAC) are small functional extrachromosomal elements, which segregate correctly during each cell division. In human cells, they are mitotically stable, however when the HAC are transferred to murine cells they show an increased and variable rate of loss. In some cell lines the HAC are lost over a short period of time, while in others the HAC become stable without acquiring murine DNA.

RESULTS

In this study, we linked the loss rate to the position of the HAC in the murine cell nucleus with respect to the chromocenters. HAC that associated preferentially with the chromocenter displayed a lower loss rate compared to the HAC that are less frequently associated. The chromocenter acts as a hub for the deposition of heterochromatic markers, controlling centromeric and pericentromeric DNA replication timing and chromosome segregation. The HAC which localized more frequently outside the chromocenters bound variable amounts of histone H3 tri-methylated at lysine 9, and the high level of intraclonal variability was associated with an increase in HAC segregation errors and delayed DNA replication timing.

CONCLUSION

This is a novel result indicating that HAC segregation is closely linked to the position in the murine nucleus and gives important insight for HAC gene expression studies in murine cells and establishing murine models of human genetic disease.

An interstitial deletion-insertion involving chromosomes 2p25.3 and Xq27.1, near SOX3, causes X-linked recessive hypoparathyroidism

X-linked recessive hypoparathyroidism, due to parathyroid agenesis, has been mapped to a 906-kb region on Xq27 that contains 3 genes (ATP11C, U7snRNA, and SOX3), and analyses have not revealed mutations. We therefore characterized this region by combined analysis of single nucleotide polymorphisms and sequence-tagged sites. This identified a 23- to 25-kb deletion, which did not contain genes. However, DNA fiber-FISH and pulsed-field gel electrophoresis revealed an approximately 340-kb insertion that replaced the deleted fragment. Use of flow-sorted X chromosome-specific libraries and DNA sequence analyses revealed that the telomeric and centromeric breakpoints on X were, respectively, approximately 67 kb downstream of SOX3 and within a repetitive sequence. Use of a monochromosomal somatic cell hybrid panel and metaphase-FISH mapping demonstrated that the insertion originated from 2p25 and contained a segment of the SNTG2 gene that lacked an open reading frame. However, the deletion-insertion [del(X)(q27.1) inv ins (X;2)(q27.1;p25.3)], which represents a novel abnormality causing hypoparathyroidism, could result in a position effect on SOX3 expression. Indeed, SOX3 expression was demonstrated, by in situ hybridization, in the developing parathyroid tissue of mouse embryos between 10.5 and 15.5 days post coitum. Thus, our results indicate a likely new role for SOX3 in the embryonic development of the parathyroid glands.

Structural analysis and expression profile of a novel gene on chromosome 5q23 encoding a Golgi-associated protein with six splice variants, and involved within the 5q deletion of a Ph(-) CML patient

We have identified a novel gene, upstream of the cytokine gene cluster region in 5q23-31, residing within one of the most common deleted segments associated with MDS. The novel gene exhibits significant alternative splicing generating at least six splice variants encoding four putative proline-rich protein isoforms, one of which is Golgi-associated. The gene is ubiquitously expressed and conserved among species with the C. elegans homologue being the most interesting, since it resides within an operon with two other genes, phospholipase D and dishevelled, a member of the Wnt pathway, suggesting a functional association. In addition, the novel gene and other key regulatory genes of the region, such IL3, Ril, AF5q31 and TCF-1, were found to be deleted in an atypical CML case, thus underscoring the significance of this subregion in the leukemogenesis process.

Mapping of three translocation breakpoints associated with orofacial clefting within 6p24 and identification of new transcripts within the region

Orofacial clefting (OFC) is a common congenital malformation. Here we report the refinement of three translocation breakpoints of patients exhibiting OFC within the 6p24 region, and the isolation and characterisation of novel genes, one of which is directly disrupted by the translocation breakpoint of a patient. The gene has been characterized and orthologues identified in bovine, murine and pufferfish.

Unexpected complexity in the haplotypes of commonly used inbred strains of laboratory mice

Investigation of sequence variation in common inbred mouse strains has revealed a segmented pattern in which regions of high and low variant density are intermixed. Furthermore, it has been suggested that allelic strain distribution patterns also occur in well defined blocks and consequently could be used to map quantitative trait loci (QTL) in comparisons between inbred strains. We report a detailed analysis of polymorphism distribution in multiple inbred mouse strains over a 4.8-megabase region containing a QTL influencing anxiety. Our analysis indicates that it is only partly true that the genomes of inbred strains exist as a patchwork of segments of sequence identity and difference. We show that the definition of haplotype blocks is not robust and that methods for QTL mapping may fail if they assume a simple block-like structure.

Allelic variation in normal human FBN1 expression in a family with Marfan syndrome: a potential modifier of phenotype?

FBN1 mutations cause Marfan syndrome (MFS), an autosomal dominant disorder of connective tissue. One of the unexplained features of MFS is the pathogenic mechanism that leads to marked inter- and intra-familial clinical variability, despite complete disease penetrance. An FBN1 deletion patient [46,XXdel(15)(q15q22.1)] was identified whose fibrillin-1 protein and mRNA levels were significantly higher than expected for a single FBN1 allele. This suggested that allelic variation in normal FBN1 expression might occur in MFS families, and have potential clinical implications particularly for those with premature termination codon (PTC) mutations who usually display low levels of expression from the mutant allele due to nonsense-mediated decay (NMD). RNA analyses identified a variable reduction in total FBN1 transcript (78+/-2.2 to 27.3+/-2.3%) in three related individuals carrying PTC-causing mutation 932insT, compared with unaffected control individuals. Both pulse chase analysis of fibrillin-1 biosynthesis and RNase protection analyses demonstrated that these differences were due to variation in the expression of the normal FBN1 allele and not NMD of mutant RNA. We suggest that differences in normal FBN1 expression could contribute to the clinical variability seen in this family with MFS, and should be considered as a potential modifier of phenotype in other cases of MFS.

Tetrahydrobiopterin-dependent preservation of nitric oxide-mediated endothelial function in diabetes by targeted transgenic GTP-cyclohydrolase I overexpression

Increased production of reactive oxygen species and loss of endothelial NO bioactivity are key features of vascular disease states such as diabetes mellitus. Tetrahydrobiopterin (BH4) is a required cofactor for eNOS activity; pharmacologic studies suggest that BH4 may mediate some of the adverse effects of diabetes on eNOS function. We have now investigated the importance and mechanisms of BH4 availability in vivo using a novel transgenic mouse model with endothelial-targeted overexpression of the rate-limiting enzyme in BH4 synthesis, guanosine triphosphate-cyclohydrolase I (GTPCH). Transgenic (GCH-Tg) mice demonstrated selective augmentation of endothelial BH4 levels. In WT mice, induction of diabetes with streptozotocin (STZ) increased vascular oxidative stress, resulting in oxidative loss of BH4, forming BH2 and biopterin. Endothelial cell superoxide production in diabetes was increased, and NO-mediated endothelium-dependent vasodilatation was impaired. In diabetic GCH-Tg mice, superoxide production from the endothelium was markedly reduced compared with that of WT mice, endothelial BH4 levels were maintained despite some oxidative loss of BH4, and NO-mediated vasodilatation was preserved. These findings indicate that BH4 is an important mediator of eNOS regulation in diabetes and is a rational therapeutic target to restore NO-mediated endothelial function in diabetes and other vascular disease states.

Genomic studies of gene expression: regulation of the Wilson disease gene

Bacterial artificial chromosomes (BACs) have many advantages over other large-insert cloning vectors and have been used for a variety of genetic applications, including the final contigs of the human genome. We describe the utilization of a BAC construct to study gene regulation in a tissue culture-based system, using a 170-kb clone containing the entire Wilson disease (WND) locus as a model. A second BAC construct that lacked a putative negatively regulating promoter sequence was created. A nonviral method of gene delivery was applied to transfect three human cell lines stably with each construct. Our results show correct WND gene expression from the recombinant locus and quantification revealed significantly increased expression from the clone lacking the negative regulator. Comparison with conventional methods confirms the reliability of the genomic approach for thorough examination of gene expression. This experimental system illustrates the potential of BAC clones in genomic gene expression studies, new gene therapy strategies, and validation of potential molecular targets for drug discovery.

Maturity-onset diabetes of the young caused by a balanced translocation where the 20q12 break point results in disruption upstream of the coding region of hepatocyte nuclear factor-4alpha (HNF4A) gene

Monogenic human disorders have been used as paradigms for complex genetic disease and as tools for establishing important insights into mechanisms of gene regulation and transcriptional control. Maturity-onset diabetes of the young (MODY) is a monogenic dominantly inherited form of diabetes that is characterized by defective insulin secretion from the pancreatic beta-cells. A wide variety of mutation types in five different genes have been identified that result in this condition. There have been no reports of a chromosome deletion or translocation resulting in MODY. We report a pedigree where MODY cosegregates with a balanced translocation [karyotype 46, XX t(3;20) (p21.2;q12)]. The chromosome 20 break point, 20q12, is within the region of one of the known MODY genes, hepatocyte nuclear factor-4alpha (HNF4A). Fluorescence in situ hybridization analysis demonstrated that the break point does not disrupt the coding region of this gene, but it lies at least 6 kb upstream of the conventional promoter (P1). We propose that this mutation disrupts the spatial relationship between the recently described alternate distal pancreatic promoter (P2) and HNF4A. This is the first case of MODY due to a balanced translocation, and it provides evidence to confirm the crucial role of an upstream regulator of HNF4A gene expression in the beta-cell.