GBA1 inactivation in oligodendrocytes affects myelination and induces neurodegenerative hallmarks and lipid dyshomeostasis in mice

BACKGROUND

Mutations in the β-glucocerebrosidase (GBA1) gene do cause the lysosomal storage Gaucher disease (GD) and are among the most frequent genetic risk factors for Parkinson's disease (PD). So far, studies on both neuronopathic GD and PD primarily focused on neuronal manifestations, besides the evaluation of microglial and astrocyte implication. White matter alterations were described in the central nervous system of paediatric type 1 GD patients and were suggested to sustain or even play a role in the PD process, although the contribution of oligodendrocytes has been so far scarcely investigated.

METHODS

We exploited a system to study the induction of central myelination in vitro, consisting of Oli-neu cells treated with dibutyryl-cAMP, in order to evaluate the expression levels and function of β-glucocerebrosidase during oligodendrocyte differentiation. Conduritol-B-epoxide, a β-glucocerebrosidase irreversible inhibitor was used to dissect the impact of β-glucocerebrosidase inactivation in the process of myelination, lysosomal degradation and α-synuclein accumulation in vitro. Moreover, to study the role of β-glucocerebrosidase in the white matter in vivo, we developed a novel mouse transgenic line in which β-glucocerebrosidase function is abolished in myelinating glia, by crossing the Cnp1-cre mouse line with a line bearing loxP sequences flanking Gba1 exons 9-11, encoding for β-glucocerebrosidase catalytic domain. Immunofluorescence, western blot and lipidomic analyses were performed in brain samples from wild-type and knockout animals in order to assess the impact of genetic inactivation of β-glucocerebrosidase on myelination and on the onset of early neurodegenerative hallmarks, together with differentiation analysis in primary oligodendrocyte cultures.

RESULTS

Here we show that β-glucocerebrosidase inactivation in oligodendrocytes induces lysosomal dysfunction and inhibits myelination in vitro. Moreover, oligodendrocyte-specific β-glucocerebrosidase loss-of-function was sufficient to induce in vivo demyelination and early neurodegenerative hallmarks, including axonal degeneration, α-synuclein accumulation and astrogliosis, together with brain lipid dyshomeostasis and functional impairment.

CONCLUSIONS

Our study sheds light on the contribution of oligodendrocytes in GBA1-related diseases and supports the need for better characterizing oligodendrocytes as actors playing a role in neurodegenerative diseases, also pointing at them as potential novel targets to set a brake to disease progression.

Collagen VI promotes recovery from colitis by inducing lymphangiogenesis and drainage of inflammatory cells

Despite a number of studies providing evidence that the extracellular matrix (ECM) is an active player in the pathogenesis of intestinal inflammation, knowledge on the actual contribution of specific ECM molecules in the progression of inflammatory bowel disease (IBD) remains scant. Here, we investigated the role of a major ECM protein, collagen VI (ColVI), in gut homeostasis and elucidated the impact of its deregulation on the pathophysiology of IBD. To this end, we combined in vivo and ex vivo studies on wild type and ColVI-deficient (Col6a1-/- ) mice both under physiological conditions and during experimentally induced acute colitis and its subsequent recovery, by means of gut histology and immunostaining, gene expression, bone marrow transplantation, flow cytometry of immune cell subpopulations, and lymph flow assessment. We found that ColVI displayed dynamic expression and ECM deposition during the acute inflammatory and recovery phases of experimentally induced colitis, whereas the genetic ablation of ColVI in Col6a1 null mice impaired the functionality of lymphatic vessels, which in turn affected the resolution of inflammation during colitis. Based on these findings, we investigated ColVI expression and deposition in ileal specimens from two cohorts of patients affected by Crohn's disease (CD) and correlated ColVI abundance to clinical outcome. Our results show that high ColVI immunoreactivity in ileal biopsies of CD patients at diagnosis correlates with increased risk of surgery and that ColVI expression in biopsies taken at the resection margin during surgery, and showing inactive disease, predict disease recurrence. Our data unveil a key role for ColVI in the intestinal microenvironment, where it is involved in lymphangiogenesis and intestinal inflammation. Altogether, these findings point at the dysregulation of ColVI expression as a novel factor contributing to the onset and maintenance of inflammation in CD via mechanisms impinging on the modulation of inflammatory cell recruitment and function. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Emerging Perspectives on the Rare Tubulopathy Dent Disease: Is Glomerular Damage a Direct Consequence of ClC-5 Dysfunction?

Dent disease (DD1) is a rare tubulopathy caused by mutations in the CLCN5 gene. Glomerulosclerosis was recently reported in DD1 patients and ClC-5 protein was shown to be expressed in human podocytes. Nephrin and actin cytoskeleton play a key role for podocyte functions and podocyte endocytosis seems to be crucial for slit diaphragm regulation. The aim of this study was to analyze whether ClC-5 loss in podocytes might be a direct consequence of the glomerular damage in DD1 patients. Three DD1 kidney biopsies presenting focal global glomerulosclerosis and four control biopsies were analyzed by immunofluorescence (IF) for nephrin and podocalyxin, and by immunohistochemistry (IHC) for ClC-5. ClC-5 resulted as down-regulated in DD1 vs. control (CTRL) biopsies in both tubular and glomerular compartments (p < 0.01). A significant down-regulation of nephrin (p < 0.01) in DD1 vs. CTRL was demonstrated. CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/Caspase9) gene editing of CLCN5 in conditionally immortalized human podocytes was used to obtain clones with the stop codon mutation p.(R34Efs*14). We showed that ClC-5 and nephrin expression, analyzed by quantitative Reverse Transcription/Polymerase Chain Reaction (qRT/PCR) and In-Cell Western (ICW), was significantly downregulated in mutant clones compared to the wild type ones. In addition, F-actin staining with fluorescent phalloidin revealed actin derangements. Our results indicate that ClC-5 loss might alter podocyte function either through cytoskeleton disorganization or through impairment of nephrin recycling.

Emilin-2 is a component of bone marrow extracellular matrix regulating mesenchymal stem cell differentiation and hematopoietic progenitors

Background

Dissection of mechanisms involved in the regulation of bone marrow microenvironment through cell–cell and cell–matrix contacts is essential for the detailed understanding of processes underlying bone marrow activities both under physiological conditions and in hematologic malignancies. Here we describe Emilin-2 as an abundant extracellular matrix component of bone marrow stroma.

Methods

Immunodetection of Emilin-2 was performed in bone marrow sections of mice from 30 days to 6 months of age. Emilin-2 expression was monitored in vitro in primary and mesenchymal stem cell lines under undifferentiated and adipogenic conditions. Hematopoietic stem cells and progenitors in bone marrow of 3- to 10-month-old wild-type and Emilin-2 null mice were analyzed by flow cytometry.

Results

Emilin-2 is deposited in bone marrow extracellular matrix in an age-dependent manner, forming a meshwork that extends from compact bone boundaries to the central trabecular regions. Emilin-2 is expressed and secreted by both primary and immortalized bone marrow mesenchymal stem cells, exerting an inhibitory action in adipogenic differentiation. In vivo Emilin-2 deficiency impairs the frequency of hematopoietic stem/progenitor cells in bone marrow during aging.

Conclusion

Our data provide new insights in the contribution of bone marrow extracellular matrix microenvironment in the regulation of stem cell niches and hematopoietic progenitor differentiation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02674-2.

Electrospun Structures Made of a Hydrolyzed Keratin-Based Biomaterial for Development of in vitro Tissue Models

The aim of this study is the analysis and characterization of a hydrolyzed keratin-based biomaterial and its processing using electrospinning technology to develop in vitro tissue models. This biomaterial, extracted from poultry feathers, was mixed with type A porcine gelatin and cross-linked with γ-glycidyloxy-propyl-trimethoxy-silane (GPTMS) to be casted initially in the form of film and characterized in terms of swelling, contact angle, mechanical properties, and surface charge density. After these chemical-physical characterizations, electrospun nanofibers structures were manufactured and their mechanical properties were evaluated. Finally, cell response was analyzed by testing the efficacy of keratin-based structures in sustaining cell vitality and proliferation over 4 days of human epithelial, rat neuronal and human primary skin fibroblast cells.

Application of FRET Microscopy to the Study of the Local Environment and Dynamics of DNA SAMs on Au Electrodes

Immobilized DNA probe strands self-assembled on an electrode surface are the bases of many electrochemically based biosensors. Control or measurement of the local environment around each DNA molecule tethered to the electrode surface is needed because the local environment can influence the binding or hybridization efficiency of the target in solution. Measurement of this local environment in buffer or under electrochemical control can be challenging. Here we demonstrate the use of fluorescence microscopy and a Förster resonance energy transfer (FRET) methodology to characterize multicomponent DNA SAMs. The DNA SAMs that were studied were composed of a series of mole fraction ratios of alkylthiol-modified DNA which was labeled with either AlexaFluor488 or AlexaFluor647, a FRET donor and acceptor, respectively. The DNA SAMs were hybridized before assembly onto the electrode surface. Wide-field filter-based FRET microscopy was used to study the assembly of DNA SAMs onto gold bead electrodes. These single-crystal gold bead electrodes contain many surface crystallographic regions which enable the comparison of the adsorbed DNA local environment. These surfaces show that most surface modifications are uniformly prepared, and the FRET efficiency can be explained through simple surface density considerations. The FRET efficiency for different compositions of the donor and acceptor for these regions is also explained through 2D FRET modeling. Not all surfaces were similar to the (111) and (110) regions showing deviations from the expected FRET behavior. Also demonstrated is FRET imaging using a confocal microscope. This approach proves useful in the analysis of a more dynamic system, such as the analysis of reductive desorption of the mixed-component DNA SAM. FRET microscopy is useful for surface analysis of the DNA local environment, enabling a measure of the surface modification, local density, and clustering and eventually a new detection modality.

The ablation of the matricellular protein EMILIN2 causes defective vascularization due to impaired EGFR-dependent IL-8 production affecting tumor growth

EMILIN2 is an extracellular matrix constituent playing an important role in angiogenesis; however, the underlying mechanism is unknown. Here we show that EMILIN2 promotes angiogenesis by directly binding epidermal growth factor receptor (EGFR), which enhances interleukin-8 (IL-8) production. In turn, IL-8 stimulates the proliferation and migration of vascular endothelial cells. Emilin2 null mice were generated and exhibited delayed retinal vascular development, which was rescued by the administration of the IL-8 murine ortholog MIP-2. Next, we assessed tumor growth and tumor-associated angiogenesis in these mice. Tumor cell growth in Emilin2 null mice was impaired as well as the expression of MIP-2. The vascular density of the tumors developed in Emilin2 null mice was prejudiced and vessels perfusion, as well as response to chemotherapy, decreased. Accordingly, human tumors expressing high levels of EMILIN2 were more responsive to chemotherapy. These results point at EMILIN2 as a key microenvironmental cue affecting vessel formation and unveil the possibility to develop new prognostic tools to predict chemotherapy efficacy.

Collagen VI Null Mice as a Model for Early Onset Muscle Decline in Aging

Collagen VI is an extracellular matrix (ECM) protein playing a key role in skeletal muscles and whose deficiency leads to connective tissue diseases in humans and in animal models. However, most studies have been focused on skeletal muscle features. We performed an extensive proteomic profiling in two skeletal muscles (diaphragm and gastrocnemius) of wild-type and collagen VI null (Col6a1^−/−) mice at different ages, from 6- (adult) to 12- (aged) month-old to 24 (old) month-old. While in wild-type animals the number of proteins and the level of modification occurring during aging were comparable in the two analyzed muscles, Col6a1^−/− mice displayed a number of muscle-type specific variations. In particular, gastrocnemius displayed a limited number of dysregulated proteins in adult mice, while in aged muscles the modifications were more pronounced in terms of number and level. In diaphragm, the differences displayed by 6-month-old Col6a1^−/− mice were more pronounced compared to wild-type mice and persisted at 12 months of age. In adult Col6a1^−/− mice, the major variations were found in the enzymes belonging to the glycolytic pathway and the tricarboxylic acid (TCA) cycle, as well as in autophagy-related proteins. When compared to wild-type animals Col6a1^−/− mice displayed a general metabolic rewiring which was particularly prominent the diaphragm at 6 months of age. Comparison of the proteomic features and the molecular analysis of metabolic and autophagic pathways in adult and aged Col6a1^−/− diaphragm indicated that the effects of aging, culminating in lipotoxicity and autophagic impairment, were already present at 6 months of age. Conversely, the effects of aging in Col6a1^−/− gastrocnemius were similar but delayed becoming apparent at 12 months of age. A similar metabolic rewiring and autophagic impairment was found in the diaphragm of 24-month-old wild-type mice, confirming that fatty acid synthase (FASN) increment and decreased microtubule-associated proteins 1A/1B light chain 3B (LC3B) lipidation are hallmarks of the aging process. Altogether these data indicate that the diaphragm of Col6a1^−/− animal model can be considered as a model of early skeletal muscle aging.

Abstract 615: Transactivation of EGFR by TGFβ Induces Hypertension by Increasing Arteriolar Myogenic Response

Myogenic tone (MT) is an intrinsic property of arteriolar smooth muscle cells (SMCs) that contract when intraluminal pressure is increased. MT is a relevant physiological mechanism to maintain stable blood flow through important organs like kidney and brain, thus preventing organ damage that could derive from increase in blood pressure (BP). On the other hand, enhancement of the basal MT could raise BP by increasing systemic vascular resistance, thus further contributing to hypertension. Several studies in animal models suggest that primary dysfunctions in SMCs can directly cause abnormalities in BP. However, in hypertensive animal models investigated so far, the increment of MT is accompanied by a stronger response to G protein coupled receptor (GPCR) agonists, thus making it difficult to distinguish whether increased vascular resistance and BP are primary effects of a more robust MT or the consequence of increased reactivity to agonists. Here we show an increased MT in mice deficient of Emilin1 , an extracellular inhibitor of TGFβ signaling, displaying a phenotype of spontaneous hypertension. We also found that the higher TGFβ signaling in Emilin1 deficient SMCs stimulates heparin binding epidermal growth factor (HB-EGF) expression and subsequent transactivation of the EGF receptor. When step-increases in intraluminal pressure are applied to mesenteric resistance arteries (MRA), the combined stimulation of mechanosensor and EGF transactivation results into activation of transient receptor potential classical type 6 (TRPC6) and melastatin type 4 (TRPM4) channels, stimulation of voltage dependent calcium channels (VDCC). To put our data into translational perspective, we measured MT on resistance arteries isolated from hypertensive patients and untreated normotensives, finding increased MT and TGFβ signaling in the former group. In addition, by using an antibody neutralizing EGFR signaling we found a normalization of the increased MT, thus confirming the relevance of TGFβ-EGFR pathway in humans. Overall our results suggest that primary increase of MT induced by TGFβ-EGFR transactivation can cause hypertension and that higher TGFβ-EGFR signaling and MT are common alterations of resistance arteries of hypertensive patients.

Open microwave cavity for use in a Purcell enhancement cooling scheme

A microwave cavity is described which can be used to cool lepton plasmas for potential use in synthesis of antihydrogen. The cooling scheme is an incarnation of the Purcell effect: when plasmas are coupled to a microwave cavity, the plasma cooling rate is resonantly enhanced through increased spontaneous emission of cyclotron radiation. The cavity forms a three electrode section of a Penning-Malmberg trap and has a bulged cylindrical geometry with open ends aligned with the magnetic trapping axis. This allows plasmas to be injected and removed from the cavity without the need for moving parts while maintaining high quality factors for resonant modes. The cavity includes unique surface preparations for adjusting the cavity quality factor and achieving anti-static shielding using thin layers of nichrome and colloidal graphite, respectively. Geometric design considerations for a cavity with strong cooling power and low equilibrium plasma temperatures are discussed. Cavities of this weak-bulge design will be applicable to many situations where an open geometry is required.

Abstract 300: Pathogenetic Mechanisms of Thoracic Aortic Aneurysm in a Smad4 Mutant Mouse Model: Identification of New Molecular Targets for Pharmacological Therapy

TGFβ signaling have been implicated in the onset of thoracic aortic aneurysms (TAAs). It has been described cases of aortic disease in humans associated to mutations in SMAD4, an intracellular transducer required in the TGFβ canonical pathway. Interestingly, Smad4 homozygotes mice are embryonically lethal and embryonic inactivation of Smad4 in smooth muscle cells leads to early death because of aortic aneurysms. In order to study mechanistic insights and potential translational target of Smad4-dependent aneurysms, we postnatally targeted the gene, using a tamoxifen (TAM) inducible Cre recombinase under the smooth muscle myosin heavy chain promoter. Echocardiography showed a progressive dilatation of aorta and TAA formation. Histological analysis revealed progressive fragmentation of elastic lamellae with increased inflammatory infiltrates at sites of disarrangement. Most of these mice died 4/6 months because of rupture of thoracic aorta. We further characterized the infiltrate of monocytes in the aorta by flow cytometry, finding a significant increase of CD11b + Ly6C hi cells and F4/80 + CD169 + resident macrophages. Thus, we hypothesized that the deletion of Smad4 should activate an immune/inflammatory mechanism in the aorta, which could be in the end responsible for the pathological phenotype. At the molecular level, we actually found a significant increase in one of the noncanonical TGFβ signaling, i.e. the p65 subunit of NFkB, a protein complex involved in regulating responses to different stressors, including cytokines. Among these, we found a selective IL1β upregulation, produced as an inactive precursor and released upon caspase1 cleavage. In turn, caspase1 requires the function of NLRP3 inflammasome, a multiprotein platform that assembles in response to infection and tissue damage and is responsible for activation of inflammatory caspases. Therefore, we also tested NLRP3 mRNA levels and found them to be significantly upregulated. Overall, we demonstrated that selective Smad4 deletion in the SMC of adult mice is sufficient to induce an immune reaction starting from the molecular alterations downstream to TGFβ signaling and culminating in the onset of TAA.

Abstract 169: Hypertension Down Regulates Emilin1 in the Extracellular Matrix of Resistance Arteries in Humans and Mice, in Order to Increase the Myogenic Tone Through Overactive TGFβ, Thus Contributing to Blood Pressure Regulation

Emilin1, a protein of the extracellular matrix of vessels, regulates TGFβ activity through proteolysis of the proTGFβ. Emilin1 KO mice, displaying increased TGFβ vascular activation, are hypertensive. As vascular Emilin1 is expressed from embryonic life to adulthood, we questioned whether the hypertensive phenotype results from a developmental defect or lack of a homeostatic role exerted in the adult. Thus, we inactivated Emilin1 in smooth muscle cells (VSMCs) of adult mice, with a tamoxifen inducible Cre -loxP, under the control of the SM myosin heavy chain promoter, finding that mice developed hypertension (HTN) as well as increased myogenic tone (MT) in resistance arteries. In order to evaluate the relevance of this mechanism in the human pathology, we enrolled 20 hypertensive (HT) and 20 normotensive (NT) patients, subjected to primary lumbar hernia neurosurgery, and dissected out resistance arteries from adipose tissue biopsies. We randomized vessels to receive vehicle, neutralizing antibody anti-TGFβ or non-relevant IgG and analyzed the MT. HT had a significantly increased MT, as compared to NT, rescued by the pretreatment with anti-TGFβ antibody. A pretreatment with the non-relevant IgG had no effect. Thus we hypothesized that Emilin1 could be down regulated by HTN to increase MT of resistances through overactive TGFβ, thus further sustaining high blood pressure (BP). In order to unravel this issue, we analyzed Emilin1 expression in the vessels walls of human arteries, finding a significant reduction in HT as compared to NT. We also evaluated Emilin1 expression in the resistance arteries of several murine models of HTN induced by: chronic AngII, DOCA-salt, L-NAME and obesity, finding that even in the experimental setting, HTN reduced Emilin1 in the vessel walls. Overall, we show that overactive TGFβ in VSMC increases the MT of resistance arteries, contributing to BP regulation. The data obtained in resistance arteries from HT and in the different murine models of HTN suggest that the down regulation of Emilin1 realized by HTN is a general mechanism to increase MT thus further sustaining high BP.

Abstract 251: Selective Deletion of Smad4 in Smooth Muscle Cells Causes Thoracic Aortic Aneurysm in Mice

TGFβ signaling have been implicated in the onset of thoracic aortic aneurysms (TAA). Recently, it has been described that mutations in SMAD4, an intracellular transducer required in the TGFβ canonical pathway, present aortic disease in humans. Although transgenic models recapitulating mutations of TGFβ pathway have been studied, Smad4 role in the onset of TAA has never been explored.

Smad4 homozygotes mice are embryonically lethal, thus, we postnatally targeted the gene, using a tamoxifen (TAM)-inducible Cre recombinase under the smooth muscle myosin heavy chain promoter. Activation by TAM suppressed Smad4 in aorta SMCs of Smadf/f;Myh11-CreERT2 mice. We found that, most of these mice died 4/6 months later from hemothorax due to rupture of thoracic aorta, while untreated mice survived. Echocardiography showed a progressive dilation of aorta and TAA formation. Histology revealed progressive fragmentation of elastic lamellae with increased inflammatory infiltrates at sites of disarrangement, rich in macrophages. At the molecular level, we found that lack of Smad4 was followed by increased levels of PSmad2 and PSmad1/5/8 early after TAM, suggesting an enhancement of TGFβ receptors activity, a condition that could increase non-canonical TGFβ signaling, the canonical one being depressed. We actually found a significant increase in one of the non-canonical TGFβ signaling, i.e. the p65 subunit of NFkB, a protein complex controlling DNA transcription and involved in regulating responses to different stress stimuli, including cytokines. Given the particular relevance that the latter molecules may have in TAA, we tested expression of some of them, finding a selective IL-1β upregulation, produced and stored in cells as an inactive precursor and released in its active form by caspase-1 cleavage. In turn, caspase-1 requires NLRP3 inflammasome, a multiprotein platform that assembles in response to infection and tissue damage and is responsible for activation of inflammatory caspases. Therefore, we also tested NLRP3 mRNA levels and found them to be significantly upregulated.

We demonstrated for the first time that selective Smad4 deletion in the SMC of adult mice is sufficient to induce ultrastructural damage and immune reaction culminating in the onset of TAA.

Synthesis and characterization of diverse Pt nanostructures in Nafion

With the aid of TEM characterization, we describe two distinct Pt nanostructures generated via the electroless reduction of Pt(NH3)4(NO2)2 within Nafion. Under one set of conditions, we produce bundles of Pt nanorods that are 2 nm in diameter and 10-20 nm long. These bundled Pt nanorods, uniformly distributed within 5 μm of the Nafion surface, are strikingly similar to the proposed hydrated nanomorphology of Nafion, and therefore strongly suggestive of Nafion templating. By altering the reaction environment (pH, reductant strength, and Nafion hydration), we can also generate nonregular polyhedron Pt nanoparticles that range in size from a few nanometers in diameter up to 20 nm. These Pt nanoparticles form a dense Pt layer within 100-200 nm from the Nafion surface and show a power-law dependence of particle size and distribution on the distance from the Nafion membrane surface. Control over the distribution and the type of Pt nanostructures in the surface region may provide a cost-effective, simple, and scaleable pathway for enhancing manufacturability, activity, stability, and utilization efficiency of Pt catalysts for electrochemical devices.

EMILIN-3, peculiar member of elastin microfibril interface-located protein (EMILIN) family, has distinct expression pattern, forms oligomeric assemblies, and serves as transforming growth factor β (TGF-β) antagonist

EMILIN-3 is a glycoprotein of the extracellular matrix belonging to a family that contains a characteristic N-terminal cysteine-rich EMI domain. Currently, EMILIN-3 is the least characterized member of the elastin microfibril interface-located protein (EMILIN)/Multimerin family. Using RNA, immunohistochemical, and protein chemistry approaches, we carried out a detailed characterization of the expression and biochemical properties of EMILIN-3 in mouse. During embryonic and postnatal development, EMILIN-3 showed a peculiar and dynamic pattern of gene expression and protein distribution. EMILIN-3 mRNA was first detected at E8.5-E9.5 in the tail bud and in the primitive gut, and at later stages it became abundant in the developing gonads and osteogenic mesenchyme. Interestingly and in contrast to other EMILIN/Multimerin genes, EMILIN-3 was not found in the cardiovascular system. Despite the absence of the globular C1q domain, immunoprecipitation and Western blot analyses demonstrated that EMILIN-3 forms disulfide-bonded homotrimers and higher order oligomers. Circular dichroism spectroscopy indicated that the most C-terminal part of EMILIN-3 has a substantial α-helical content and forms coiled coil structures involved in EMILIN-3 homo-oligomerization. Transfection experiments with recombinant constructs showed that the EMI domain contributes to the higher order self-assembly but was dispensable for homotrimer formation. EMILIN-3 was found to bind heparin with high affinity, a property mediated by the EMI domain, thus revealing a new function for this domain that may contribute to the interaction of EMILIN-3 with other extracellular matrix and/or cell surface molecules. Finally, in vitro experiments showed that EMILIN-3 is able to function as an extracellular regulator of the activity of TGF-β ligands.

A Methodology for Investigating New Nonprecious Metal Catalysts for PEM Fuel Cells

This paper reports an approach to investigate metal-chalcogen materials as catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells. The methodology is illustrated with reference to Co-Se thin films prepared by magnetron sputtering onto a glassy-carbon substrate. Scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) have been used, in parallel with electrochemical activity and stability measurements, to assess how the electrochemical performance relates to chemical composition. It is shown that Co-Se thin films with varying Se are active for oxygen reduction, although the open circuit potential (OCP) is lower than for Pt. A kinetically controlled process is observed in the potential range 0.5-0.7 V (vs reversible hydrogen electrode) for the thin-film catalysts studied. An initial exposure of the thin-film samples to an acid environment served as a pretreatment, which modified surface composition prior to activity measurements with the rotating disk electrode (RDE) method. Based on the SAM characterization before and after electrochemical tests, all surfaces demonstrating activity are dominated by chalcogen. XRD shows that the thin films have nanocrystalline character that is based on a Co(1-x)Se phase. Parallel studies on Co-Se powder supported on XC72R carbon show comparable OCP, Tafel region, and structural phase as for the thin-film model catalysts. A comparison for ORR activity has also been made between this Co-Se powder and a commercial Pt catalyst.

Amphotericin B interactions with a DOPC monolayer. Electrochemical investigations

A model lipid membrane consisting of a monolayer of dioleoyl phosphatidylcholine (DOPC) adsorbed onto a Hg electrode has been used to study the interaction between the lipid and different formulations of Amphotericin B (AmB) [Fungizone (FZ), Heated Fungizone (HFZ), and Abelcet]. The lipid organizational order was measured by electrochemical methods [capacitance and metal ion (Tl(+)) reduction], characterizing the change in lipid order due to interaction with the drug. The mean size and number density of pores formed in the monolayer were estimated by fitting the reduction current transients to a random array of microelectrode model. This method was shown sensitive for investigation of the interaction of drugs with the DOPC monolayer. Abelcet was found to have a smaller disruptive effect on lipid order than FZ and HFZ. The formulations used to solubilize the AmB were also studied. Sodium deoxycholate used as a solubilizer in FZ displayed significant influence on lipid order similar to that observed for Abelcet. The lipid complex, used in Abelcet, did not significantly perturb the DOPC monolayer order. The lipid complex used in Abelcet may have an annealing or healing effect that buffers the disruption possible due to AmB.

[Influence of hydrocortisone on the response to noradrenaline of segments of isolated coronary arteries in the presence of a beta-adrenergic blocking agent]

The effect of hydrocortisone on the noradrenaline-induces contraction, after propranolol, was studied in vitro. Contraction of response to noradrenaline were increased by hydrocortisone. We suggest that the hydrocortisone influence depends on inhibition of catecol-O-metiltransferase (COMT).