Knockdown of ANGPTL2 promotes left ventricular systolic dysfunction by upregulation of NOX4 in mice

Background: Angiopoietin-like 2 (ANGPTL2) is a pro-inflammatory and pro-oxidant circulating protein that predicts and promotes chronic inflammatory diseases such as atherosclerosis in humans. Transgenic murine models demonstrated the deleterious role of ANGPTL2 in vascular diseases, while deletion of ANGPTL2 was protective. The nature of its role in cardiac tissues is, however, less clear. Indeed, in adult mice knocked down (KD) for ANGPTL2, we recently reported a mild left ventricular (LV) dysfunction originating from a congenital aortic valve stenosis, demonstrating that ANGPTL2 is essential to cardiac development and function. Hypothesis: Because we originally demonstrated that the KD of ANGPTL2 protected vascular endothelial function via an upregulation of arterial NOX4, promoting the beneficial production of dilatory H2O2, we tested the hypothesis that increased cardiac NOX4 could negatively affect cardiac redox and remodeling and contribute to LV dysfunction observed in adult Angptl2-KD mice. Methods and results: Cardiac expression and activity of NOX4 were higher in KD mice, promoting higher levels of cardiac H2O2 when compared to wild-type (WT) mice. Immunofluorescence showed that ANGPTL2 and NOX4 were co-expressed in cardiac cells from WT mice and both proteins co-immunoprecipitated in HEK293 cells, suggesting that ANGPTL2 and NOX4 physically interact. Pressure overload induced by transverse aortic constriction surgery (TAC) promoted LV systolic dysfunction in WT mice but did not further exacerbate the dysfunction in KD mice. Importantly, the severity of LV systolic dysfunction in KD mice (TAC and control SHAM) correlated with cardiac Nox4 expression. Injection of an adeno-associated virus (AAV9) delivering shRNA targeting cardiac Nox4 expression fully reversed LV systolic dysfunction in KD-SHAM mice, demonstrating the causal role of NOX4 in cardiac dysfunction in KD mice. Targeting cardiac Nox4 expression in KD mice also induced an antioxidant response characterized by increased expression of NRF2/KEAP1 and catalase. Conclusion: Together, these data reveal that the absence of ANGPTL2 induces an upregulation of cardiac NOX4 that contributes to oxidative stress and LV dysfunction. By interacting and repressing cardiac NOX4, ANGPTL2 could play a new beneficial role in the maintenance of cardiac redox homeostasis and function.

Angiopoietin-Like Proteins: Cardiovascular Biology and Therapeutic Targeting for the Prevention of Cardiovascular Diseases

Despite the best pharmacologic tools available, cardiovascular diseases (CVDs) remain a major cause of morbidity and mortality in developed countries. After 2 decades of research, new therapeutic targets, such as angiopoietin-like proteins (ANGPTLs), are emerging. ANGPTLs belong to a family of 8 members, from ANGPTL1 to ANGPTL8; they have structural homology with angiopoietins and are secreted in the circulation. ANGPTLs display a multitude of physiological and pathologic functions; they contribute to inflammation, angiogenesis, cell death, senescence, hematopoiesis, and play a role in repair, maintenance, and tissue homeostasis. ANGPTLs-particularly the triad ANGPTL3, 4, and 8-have an established role in lipid metabolism through the regulation of triacylglycerol trafficking according to the nutritional status. Some ANGPTLs also contribute to glucose metabolism. Therefore, dysregulation in ANGPTL expression associated with abnormal circulating levels are linked to a plethora of CVD and metabolic disorders including atherosclerosis, heart diseases, diabetes, but also obesity and cancers. Because ANGPTLs bind to different receptors according to the cell type, antagonists are therapeutically inadequate. Recently, direct inhibitors of ANGPTLs, mainly ANGPTL3, have been developed, and specific monoclonal antibodies and antisense oligonucleotides are currently being tested in clinical trials. The aim of the current review is to provide an up-to-date preclinical and clinical overview on the function of the 8 members of the ANGPTL family in the cardiovascular system, their contribution to CVD, and the therapeutic potential of manipulating some of them.

Angptl2 is a Marker of Cellular Senescence: The Physiological and Pathophysiological Impact of Angptl2-Related Senescence

Cellular senescence is a cell fate primarily induced by DNA damage, characterized by irreversible growth arrest in an attempt to stop the damage. Senescence is a cellular response to a stressor and is observed with aging, but also during wound healing and in embryogenic developmental processes. Senescent cells are metabolically active and secrete a multitude of molecules gathered in the senescence-associated secretory phenotype (SASP). The SASP includes inflammatory cytokines, chemokines, growth factors and metalloproteinases, with autocrine and paracrine activities. Among hundreds of molecules, angiopoietin-like 2 (angptl2) is an interesting, although understudied, SASP member identified in various types of senescent cells. Angptl2 is a circulatory protein, and plasma angptl2 levels increase with age and with various chronic inflammatory diseases such as cancer, atherosclerosis, diabetes, heart failure and a multitude of age-related diseases. In this review, we will examine in which context angptl2 was identified as a SASP factor, describe the experimental evidence showing that angptl2 is a marker of senescence in vitro and in vivo, and discuss the impact of angptl2-related senescence in both physiological and pathological conditions. Future work is needed to demonstrate whether the senescence marker angptl2 is a potential clinical biomarker of age-related diseases.

Reduction of plasma angiopoietin-like 2 after cardiac surgery is related to tissue inflammation and senescence status of patients

OBJECTIVES

A strong relationship between high circulating angiopoietin-like 2 (ANGPTL2) levels, a proinflammatory adipokine, and cardiovascular diseases has been reported. Our objective was to determine whether plasma ANGPTL2 and high-sensitivity C-reactive protein (hs-CRP) levels change postoperatively in patients who underwent heart valve surgery and/or coronary artery bypass grafting. We hypothesized that a corrective cardiac surgery would decrease ANGPTL2 levels.

METHODS

In 47 prospectively recruited patients who underwent coronary artery bypass grafting (n = 16), valve replacement (n = 16), or both (n = 15), we measured plasma ANGPTL2 and hs-CRP levels preoperatively, at 24 hours, at 3 to 5 days (hospital discharge), and at 30 to 90 days (follow-up) after surgery. Mediastinal adipose tissue and distal fragments of the left internal mammary artery (IMA) were harvested during surgery and mRNA expression of inflammatory and senescence markers was assessed using real-time quantitative polymerase chain reaction.

RESULTS

ANGPTL2 and hs-CRP levels were elevated 24 hours after surgery and then returned to baseline levels. We noted, however, a dichotomy among patients: compared with baseline, plasma ANGPTL2 levels either significantly decreased (n = 21/47) or increased (n = 26/47) after surgery. In contrast, hs-CRP levels were identical between groups (P = .997). Patients in the increased group were older (P = .002) with a higher systolic blood pressure (P = .038) at baseline. Moreover, changes in ANGPTL2 levels (ΔANGPTL2 = final minus initial levels) positively correlated with mRNA expression of tumor necrosis factor α and interleukin 8 in mediastinal adipose tissue and IMA (P < .05) and with the senescence-associated marker cyclin-dependent kinase inhibitor 1 in IMA (P = .009).

CONCLUSIONS

In younger patients with lower levels of tissue inflammation and arterial senescence load, ANGPTL2, but not hs-CRP levels decreased after cardiac surgery, suggesting that circulating ANGPTL2 reflects tissue inflammation and senescence.

Impact of pulse pressure on cerebrovascular events leading to age-related cognitive decline

Aging is a modern concept: human life expectancy has more than doubled in less than 150 yr in Western countries. Longer life span, however, reveals age-related diseases, including cerebrovascular diseases. The vascular system is a prime target of aging: the "wear and tear" of large elastic arteries exposed to a lifelong pulsatile pressure causes arterial stiffening by fragmentation of elastin fibers and replacement by stiffer collagen. This arterial stiffening increases in return the amplitude of the pulse pressure (PP), its wave penetrating deeper into the microcirculation of low-resistance, high-flow organs such as the brain. Several studies have associated peripheral arterial stiffness responsible for the sustained increase in PP, with brain microvascular diseases such as cerebral small vessel disease, cortical gray matter thinning, white matter atrophy, and cognitive dysfunction in older individuals and prematurely in hypertensive and diabetic patients. The rarefaction of white matter is also associated with middle cerebral artery pulsatility that is strongly dependent on PP and artery stiffness. PP and brain damage are likely associated, but the sequence of mechanistic events has not been established. Elevated PP promotes endothelial dysfunction that may slowly develop in parallel with the accumulation of proinflammatory senescent cells and oxidative stress, generating cerebrovascular damage and remodeling, as well as brain structural changes. Here, we review data suggesting that age-related increased peripheral artery stiffness may promote the penetration of a high PP to cerebral microvessels, likely causing functional, structural, metabolic, and hemodynamic alterations that could ultimately promote neuronal dysfunction and cognitive decline.

The alternatively spliced LRRFIP1 Isoform-1 is a key regulator of the Wnt/β-catenin transcription pathway

The GC-rich Binding Factor 2/Leucine Rich Repeat in the Flightless 1 Interaction Protein 1 gene (GCF2/LRRFIP1) is predicted to be alternatively spliced in five different isoforms. Although important peptide sequence differences are expected to result from this alternative splicing, to date, only the gene transcription regulator properties of LRRFIP1-Iso5 were unveiled. Based on molecular, cellular and biochemical data, we show here that the five isoforms define two molecular entities with different expression profiles in human tissues, subcellular localizations, oligomerization properties and transcription enhancer properties of the canonical Wnt pathway. We demonstrated that LRRFIP1-Iso3, -4 and -5, which share over 80% sequence identity, are primarily located in the cell cytoplasm and form homo and hetero-multimers between each other. In contrast, LRRFIP1-Iso1 and -2 are primarily located in the cell nucleus in part thanks to their shared C-terminal domain. Furthermore, we showed that LRRFIP1-Iso1 is preferentially expressed in the myocardium and skeletal muscle. Using the in vitro Topflash reporter assay we revealed that among LRRFIP1 isoforms, LRRFIP1-Iso1 is the strongest enhancer of the β-catenin Wnt canonical transcription pathway thanks to a specific N-terminal domain harboring two critical tryptophan residues (W76, 82). In addition, we showed that the Wnt enhancer properties of LRRFIP1-Iso1 depend on its homo-dimerisation which is governed by its specific coiled coil domain. Together our study identified LRRFIP1-Iso1 as a critical regulator of the Wnt canonical pathway with a potential role in myocyte differentiation and myogenesis.

High chlorpyrifos resistance in Culex pipiens mosquitoes: strong synergy between resistance genes

We investigated the genetic determinism of high chlorpyrifos resistance (HCR), a phenotype first described in 1999 in Culex pipiens mosquitoes surviving chlorpyrifos doses ⩾1 mg l(-1) and more recently found in field samples from Tunisia, Israel or Indian Ocean islands. Through chlorpyrifos selection, we selected several HCR strains that displayed over 10 000-fold resistance. All strains were homozygous for resistant alleles at two main loci: the ace-1 gene, with the resistant ace-1(R) allele expressing the insensitive G119S acetylcholinesterase, and a resistant allele of an unknown gene (named T) linked to the sex and ace-2 genes. We constructed a strain carrying only the T-resistant allele and studied its resistance characteristics. By crossing this strain with strains harboring different alleles at the ace-1 locus, we showed that the resistant ace-1(R) and the T alleles act in strong synergy, as they elicited a resistance 100 times higher than expected from a simple multiplicative effect. This effect was specific to chlorpyrifos and parathion and was not affected by synergists. We also examined how HCR was expressed in strains carrying other ace-1-resistant alleles, such as ace-1(V) or the duplicated ace-1(D) allele, currently spreading worldwide. We identified two major parameters that influenced the level of resistance: the number and the nature of the ace-1-resistant alleles and the number of T alleles. Our data fit a model that predicts that the T allele acts by decreasing chlorpyrifos concentration in the compartment targeted in insects.

Controlled surface density of RGD ligands for cell adhesion: evidence for ligand specificity by using QCM-D

A critical interligand spacing is required to observe selective cell adhesion.

Genetic variations in host IL28B links to the detection of peripheral blood mononuclear cells-associated hepatitis C virus RNA in chronically infected patients

Hepatitis C virus (HCV) is mainly hepatotropic; however, several reports document the presence of genomic viral RNA in extrahepatic sites including peripheral blood mononuclear cells (PBMCs). In this study, the presence of HCV RNA was initially evaluated in the plasma and peripheral blood mononuclear cells (PBMCs) of 53 HCV-infected patients who were treated per protocol. PBMC-associated HCV RNA was detectable in 79% of patients. Early virological response to combined pegylated interferon-α (PegIFN) and ribavirin (RBV) therapy in patients with undetectable levels of PBMCs-associated HCV RNA was 100%, while it was 60% (P = 0.003) in those who had detectable levels of PBMC-associated HCV RNA. A sustained virological response was observed in 35% of patients with detectable PBMC-associated HCV RNA, but was 70% in patients with undetectable levels of PBMC-associated HCV RNA (P = 0.07). In a multivariate analysis incorporating parameters such as HCV genotype, viral load, presence of cirrhosis and absence of PBMC-associated HCV RNA, a significant relationship was observed between the detection of PBMC-associated HCV RNA and the sustained virological response (OR 19.4, 95% CI: 2.1-486.2, P = 0.0061). The association between single nucleotide polymorphism (SNP) in IL28B, known predictor of antiviral therapy outcome, and the occurrence of HCV RNA in PBMC in 84 chronically infected patients was then evaluated. Results suggest that the presence of a G allele in rs8099917, known to associate to a poor response to PegIFN/RBV therapy, also predicts an increased association of HCV RNA with PBMC (OR: 3.564; 95% CI: 1.114-11.40, P = 0.0437).

Unraveling the spatial distribution of immunoglobulins, enzymes, and polyelectrolytes within layer-by-layer self-assembled multilayers. Ellipsometric studies

The ellipsometric characterization of a layer-by-layer electrostatically self-assembled multilayer of polyphenol oxidase and alkaline phosphatase with the polycation poly(dimethyldiallylammonium chloride) built on an immunologic layer formed by immunoglobulin G (IgG) and glucose oxidase-conjugated anti-IgG (IgG-GOD) on glassy carbon is reported. The step-by-step evolution of the psi-Delta ellipsometric angles was followed during film growth. Two optical models, named the three-layer film model and reorganization film model, were employed and found suitable for ellipsometric data interpretation. A comparative analysis of film optical properties, film thickness, and ellipsometric mass assessed from both models is also presented.

Multivalent ion/polyelectrolyte exchange processes in exponentially growing multilayers

We show, in this paper that multivalent ferrocyanide anions can penetrate into exponentially growing (PGA/PAH)n multilayer films whatever the nature of the last deposited layer. These ions are not able to diffuse out of the film when it is brought in contact with a pure buffer solution. However, the contact of this film with a poly(allylamine) (PAH) or a poly(L-glutamic acid) (PGA) solution leads to the release of ferrocyanide ions from the multilayer. It is shown that the release of ferrocyanide anions, when the film is in contact with a PGA solution, is due to the diffusion of the PGA chains into the film so that an exchange between ferrocyanide ions and PGA chains takes place inside the film. On the other hand, PAH chains do not diffuse into PGA/PAH multilayers. When the film is then brought in contact with a PAH solution, the PAH chains from the solution are expected to strongly interact with the ferrocyanide ions and thus induce a diffusion mechanism of the multivalent anions out of the film, the film/solution interface playing the role of a sink for these ions. This work thus shows that interactions between multivalent ions and exponentially growing films are much more complex than expected at first sight and that polyelectrolyte multilayers must be seen as dynamic entities in which diffusion and exchange processes can take place.

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

Phosphate tungsten bronzes have been shown to be conductors of low dimensionality. A review of the crystallographic and structural properties of this huge series of compounds is given here, corresponding to the present knowledge of the different X-ray studies and electron microscopy investigations. Three main families are described, monophosphate tungsten bronzes, Ax(PO2)4(WO3)2m, either with pentagonal tunnels (MPTBp) or with hexagonal tunnels (MPTBh), and diphosphate tungsten bronzes, Ax(P2O4)2(WO3)2m, mainly with hexagonal tunnels (DPTBh). The general aspect of these crystal structures may be described as a building of polyhedra sharing oxygen corners made of regular stacking of WO3-type slabs with a thickness function of m, joined by slices of tetrahedral PO4 phosphate or P2O7 diphosphate groups. The relations of the different slabs with respect to the basic perovskite structure are mentioned. The structural description is focused on the tilt phenomenon of the WO6 octahedra inside a slab of WO3-type. In this respect, a comparison with the different phases of the WO3 crystal structures is established. The various modes of tilting and the different possible connections between two adjacent WO3-type slabs involve a great variety of structures with different symmetries, as well as the existence of numerous twins in MPTBp's. Several phase transitions, with the appearance of diffuse scattering and modulation phenomena, were analysed by X-ray scattering measurements and through the temperature dependence of various physical properties for the MPTBp's. The role of the W displacements within the WO3-type slabs, in two modulated structures (m = 4 and m = 10), already solved, is discussed. Finally, the complexity of the structural aspects of DPTBh's is explained on the basis of the average structures which are the only ones solved.

Amplification of amperometric biosensor responses by electrochemical substrate recycling. 3. Theoretical and experimental study of the phenol-polyphenol oxidase system immobilized in Laponite hydrogels and layer-by-layer self-assembled structures

The amperometric response toward phenol of PPO-based rotating disk bioelectrodes is analyzed on the basis of a kinetic model taking into account internal and external mass transport effects and a CEC' electroenzymatic mechanism. Monophenolase activity of PPO catalyses the oxidation of phenol to o-quinone (step C). o-Quinone can then enter an amplification recycling process involving electrochemical reduction (step E) and enzymatic reoxidation (step C': catecholase activity). The rate-limiting steps such as monophenolase activity, catecholase recycling, permeability of the membrane, and activity and accessibility of the catalytic enzyme sites are theoretically considered and experimentally demonstrated for different electrode configurations including PPO immobilized in Laponite hydrogels and layer-by-layer self-assembled multilayers of PPO and poly(diallyldimethylammonium).

Functional responses of human neutrophils to sodium sulfite (Na2SO3) in vitro

An influx of neutrophils into the airways is a common feature observed during pulmonary inflammation induced by air pollutants, including sulfur dioxide and sulfates. In the present study focusing on the in vitro interactions of sodium sulfite (Na2SO3) with human neutrophils, we confirm results indicating that this sulfite induces superoxide production (O2-) by itself. We demonstrated that this response can occur more rapidly than previously reported (within 5 min), and that Na2SO3 can act as a priming agent, in a concentration-dependent fashion, to the bacterial tripeptide N-formyl-methionine-leucine-phenylalanine (fMLP) by increasing O2-production. In addition, our results show that Na2SO3 induces gene expression in human neutrophils in a concentration-dependent manner as assessed by incorporation of 5-[3H] uridine into total RNA. However, it does not induce cell shape changes. We also demonstrated that Na2SO3 does not modulate neutrophil apoptosis nor reverse the well-known delaying effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on apoptosis. We conclude that Na2SO3 acts rapidly on neutrophil physiology, within a few minutes with respect to superoxide production, and a few hours (4 h) with respect to gene expression without altering a biological process such as the rate of apoptosis evaluated after a long period of incubation (20 h). We further conclude that Na2SO3-induced production of O2does not drive neutrophils to undergo apoptosis, a mechanism known to occur in other conditions. Therefore, the potential toxicity of Na2SO3 during pulmonary inflammation or lung-associated diseases may be related to its ability to induce superoxide production without altering neutrophil apoptosis rate.

Structural Investigation of P4W24O80: A New Monophosphate Tungsten Bronze

The crystallographic study of the tungsten phosphate bronze P4W24O80 was performed from three-dimensional single-crystal X-ray diffraction data and electron microscopy. This compound crystallizes in the orthorhombic system with unit-cell dimensions a = 5.312 (1), b = 6.5557 (8), c = 42.196 (8) Å and space group P212121. The crystal structure was solved by direct methods and Fourier techniques, and refined to the reliability factor R = 0.0284 (wR = 0.0272). Its determination confirms that it belongs to the monophosphate tungsten bronze family of the general formula (PO2)4(WO3)2m with the value m = 12. Large empty cages surrounded by 18 O atoms are built up of eight WO6 octahedra and four PO4 tetrahedra sharing corners. They are located between two WO3-type slabs forming pentagonal-shaped tunnels running in the a direction. Electron microscopy investigations confirm that the studied crystal does not imply modulation phenomena when other crystals of the same composition exhibit satellite reflections with a modulation vector q* involving a doubling of a. The observations also reveal the existence of a monoclinic form of the m = 12 compound, which is a regular intergrowth of m = 11 and m = 13 members in a similar way to the m = 5 member of the series where the same feature has already been observed. On each edge of a WO3-type slab, a large variation (from 1.73 to 2.09 Å) of the six W—O distances within the WO6 octahedron is noted, which yields an oxidation state of W near 6, whereas for the WO6 octahedra located in the middle part of the slab the six W—O distances are gathered about their mean value (1.92 Å), which involves a more important electronic delocalization. The thermal motion of the W atoms is described. The absolute structural configuration is tested on the basis of some calculated structure factors, which are more sensitive to the x, y, z → −x, −y, −z change of atomic positions.

Human coproporphyrinogen oxidase. Biochemical characterization of recombinant normal and R231W mutated enzymes expressed in E. coli as soluble, catalytically active homodimers

To obtain recombinant human coproporphyrinogen oxidase (CPX), a cDNA for the coding region of mature human CPX has been expressed in E. coli. CPX was produced as a fusion protein with glutathione S-transferase followed by the hexapeptide recognition site for thrombin cleavage just preceding first amino acid of the CPX protein. The human CPX was found to be in the soluble fraction. This previously unobtainable human heme synthetic enzyme was purified to electrophoretic homogeneity with a specific activity of 4200 nmol/hr./mg of protein using a Glutathione Sepharose 4B column and gel filtration. Recombinant human CPX exhibits homogeneous behavior during high performance liquid chromatography (HPLC) and the N-terminal sequence, confirmed by protein sequencing, revealed a single polypeptide chain. In its active form, human CPX is a homodimer. According to the hydrodynamic properties derived from analytical ultracentrifugation, dimeric CPX has a nearly globular shape. Additionally, naturally occurring Arg to Trp (R231W)-mutated CPX has been also expressed in E. coli and further characterized. The mutated enzyme has a Km value of 0.55 microM as compared to 0.30 microM for the wild type. The catalytic efficiency (specificity constant, kcat/Km) of the mutated CPX was four fold lower than wild-type enzyme. The activity measurement of the mutated enzyme showed higher thermal sensitivity as compared with wild type CPX. The measured pI for mutated CPX is 5.65, compared to 6.40 for wild type. The pH optima for the mutated and wild-type protein are 6.6 and 6.8, respectively. The R231W mutation of CPX does not affect dimer formation and both normal and mutated CPX exhibit identical sedimentation properties. The thermal denaturation of both wild type and mutant CPX was found to be irreversible. The mutated CPX contained a significant amount of tightly bound porphyrin coproporphyrin. No metal association was found either in wild type or in mutated CPX. The availability of the recombinant human CPX will aid in structural and mechanistic studies.

Characterization of a novel human antibody xenoreactive with fibronectin

Recent reports have used bovine fibronectin (Fn) as source of antigen to study human anti-Fn autoantibodies. We have characterized a novel human antibody (Ab) reactive with bovine and marsupial Fn, but not with human Fn. Indirect immunofluorescence, wet cleaving and protein adherence assays, immunoblotting, blot-affinity purification, a cell adhesion inhibition assay, and competitive experiments with synthetic peptides were used to characterize the anti-Fn Ab in serum from a patient with an undifferentiated connective tissue disease. A characteristic Fn-like network was observed by indirect immunofluorescence on bovine MDBK and marsupial PtK2 cells, but not on various human cell lines. Double immunofluorescence revealed colocalization of the Ab with a mouse monoclonal anti-Fn Ab. A reactive polypeptide of 240 kDa corresponding to the M(r) of Fn was identified by immunoblotting using MDBK and PtK2 total cell lysates. The Ab reacted with the 240-kDa band of purified bovine Fn with an endpoint titer of 1:64,000, while no reactivity was observed with human cellular or plasma Fn. Blot-affinity purification of the Ab from the 240-kDa PtK2 region confirmed that the Fn-like fluorescent pattern observed was due to reactivity with the 240-kDa band and not with other regions of the blot. The Ab affinity-purified from the 240-kDa region also reacted with purified bovine Fn by immunoblotting. Functional analysis disclosed specific inhibition of PtK2 and MDBK cell adhesion by the affinity-purified anti-Fn Ab. Competitive experiments with synthetic peptides demonstrated that the epitope is located in the decapeptide RGDSPASSKP containing the cell-binding domain of Fn. Longitudinal analysis of the Ab revealed its persistence over 6 years. Bovine and marsupial Fn can be the focus of a highly specific and persistent human immune response. Reactivity of a human Ab with bovine Fn does not imply cross-reactivity with human Fn. In light of recent reports using bovine Fn to characterize human anti-Fn "autoantibodies," future studies on human anti-Fn should specifically employ purified human Fn as antigen.

[Rheumatoid polyarthritis in the elderly--rhizomelic pseudopolyarthritis: what differences?]

The authors have conducted a comparative retrospective study between polymyalgia rheumatic (N = 26) and rheumatoid arthritis in the elderly (N = 44), including HLA DRB1 genotype determination by PCR-RFLP analysis. No clinical nor biological differences were significant between the 2 groups of patients. However 70% of RA patients had one ore more susceptibility alleles (shared epitope hypothesis) and 50% in polymyalgia rheumatica.

La1.16Mo8O16: a hollandite-related compound with an incommensurate modulated structure

The hollandite-related structure La1.16Mo8O16, Mr = 1184.66, tetragonal, P^{I4}_{\kern3pt 1}, a = 9.983 (1), c = 2.8890 (5) Å, V = 287.9 Å3, Z = 1, Dx = 6.83 g cm−3, \lambda(Mo Kα) = 0.71069 Å, μ = 126 cm−1, F(0000) = 530, room temperature, R = 0.041 for 1145 unique reflections with I\geq3σ(I). At room temperature the compound exhibits a one-dimensional incommensurate modulated structure with a modulation wavevector q* = 0.608 (1)c*. Both a displacive modulation wave, acting on La, Mo and O atoms, and a modulation wave governing the occupancy probability of La sites inside the tunnels are involved in the crystal. Within the superspace group P^{I4}_{\kern3pt 1}, the final R values of main reflections (477) and first- and second-order satellite reflections (523 and 145) are 0.030, 0.050 and 0.133 respectively. The more spectacular modulation features are the occurrence of La—La pairs in the tunnels and the formation of Mo3 triangular clusters in the double chains of edge-sharing octahedra. Contrary to previous descriptions based upon rigid tunnels in structures of the hollandite type, the tunnels in the crystal studied are distorted in a periodic way along [001] (λ = 4.75 Å), giving rise to alternate contractions and expansions. The distortion of the double octahedral chains is considerable and probably created via the La—O(1) bonds by insertion of La atoms inside two adjacent tunnels.