Different Factors Affecting Human ANP Amyloid Aggregation and Their Implications in Congestive Heart Failure

Atrial Natriuretic Peptide (ANP)-containing amyloid is frequently found in the elderly heart. No data exist regarding ANP aggregation process and its link to pathologies. Our aims were: i) to experimentally prove the presumptive association of Congestive Heart Failure (CHF) and Isolated Atrial Amyloidosis (IAA); ii) to characterize ANP aggregation, thereby elucidating IAA implication in the CHF pathogenesis.A significant prevalence (85\%) of IAA was immunohistochemically proven ex vivo in biopsies from CHF patients. We investigated in vitro (using Congo Red, Thioflavin T, SDS-PAGE, transmission electron microscopy, infrared spectroscopy) ANP fibrillogenesis, starting from α-ANP as well as the ability of dimeric β-ANP to promote amyloid formation. Different conditions were adopted, including those reproducing β-ANP prevalence in CHF. Our results defined the uncommon rapidity of α-ANP self-assembly at acidic pH supporting the hypothesis that such aggregates constitute the onset of a fibrillization process subsequently proceeding at physiological pH. Interestingly, CHF-like conditions induced the production of the most stable and time-resistant ANP fibrils suggesting that CHF affected people may be prone to develop IAA.We established a link between IAA and CHF by ex vivo examination and assessed that β-ANP is, in vitro, the seed of ANP fibrils. Our results indicate that β-ANP plays a crucial role in ANP amyloid deposition under physiopathological CHF conditions. Overall, our findings indicate that early IAA-related ANP deposition may occur in CHF and suggest that these latter patients should be monitored for the development of cardiac amyloidosis

New data on marinellite, a mineral of the cancrinite-sodalite group

Marinellite, a cancrinite-group mineral with ideal composition [(Na,K)42Ca6](Si36Al36O144)(SO4)8Cl26•H2O was reported for the firts time (Bonaccorsi and Orlandi, 2003) from Valle Biachella, Sacrofano (Roma, Italy). The crystal structure of marinellite [P31c with a = 12,880(2) Å and c = 31,761(6) Å] is characterized by columns of liottite cages running along [0, 0, z] and columns of cancrinite + sodalite cages staked along [1/3, 2/3, z] and [2/3, 1/3, z]. Na+, Ca2+ and K+, SO42- and Cl- are hosted within the liottite cages, while additional H2O and Na+ are hosted within the cancrinite cages. We describe here a new occurrence of marinellite from Magliano Romano, Sabatini Volcanic Complex north of Rome. The mineral is found as millimetric-sized, transparent to trasluncent, vitreous, light-blue colored, anhedral grains, within holocrystalline volcanic ejecta associated with biotite, clinopyroxene, and Fe-oxides. Powder diffraction data were collected with a Scintag X1 diffractometer (CuKα, solid state detector); EMP analyses were done using a CAMEBAX 50X WDS-microprobe (15 kV accelerating voltage, 4 nA beam current, spot size 20 μm). Powder-FTIR spectra were collected on KBr pellets with a spectrometer Nicolet Magna 760 (KBr beamsplitter, DTGS detector, Globar source); polarized micro-FTIR single crystal spectra were collected on oriented, doubly-polished slabs, using a NicPlan microscope equipped with a nitrogen-cooled MCT detector and a ZnSe wire-grid IR polarizer. The cell parameters: a = 12,881(1) Å, c = 31,764(4) Å, V = 4564,3(7) Å3, and the chemical formula of marinellite from Magliano Romano: (Na29.97K11.57Ca6.55)=48.09(Si35.93Al36.07)=72.00O144[(SO4)7.93Cl1.65(CO3)0.52]=10.11•5.77H2O, are close to those of the holotype specimen from Valle Biachella. Powder-FTIR spectra show the absorptions due to H2O (1/3 at 3500 cm-1 and 2 at 1630 cm-1), SO4 (3 at 1100 cm-1) and the alumino-silicate framework ( 1000 cm-1 and below). Single crystal polarized FTIR spectra shows the absorptions due to CO3 groups (3 1400 cm-1), H2O molecules, and two very unusual absorptions, due to molecular CO2 (Della Ventura et al. 2005, 2007a, 2007b), at 2352 and 2341 cm-1. The first component is almost completely polarized for E c, while the second one has an isotropic behaviour. The polarization behavior of H2O stretching and bending bands is quite complex and shows the presence of two different water molecules within the structural channels, in agreement with the presence of two bending absorptions at around 1630 cm-1. References Bonaccorsi E., Orlandi P. (2003) Eur. J. Mineral., 15, 1019-1027. Della Ventura, G., Bellatreccia, F. and Bonaccorsi, E. (2005) Eur. J. Mineral., 17, 847-851. Della Ventura G., Bellatreccia F., Parodi G.C., Cámara F., Piccinini M. (2007a) Am. Mineral. (in press). Della Ventura G., Bellatreccia F., Piccinini M. (2007b) Rend. Fis. Acc. Lincei (in press)