An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An 18-year-old male presented with syncope during a training break. Post-syncope, he developed effort dyspnea, which he associated with the Pfizer-BioNTech COVID-19 vaccine received a week earlier. Electrocardiogram showed T inversion in V1-V3, III, and aVF, while 24-hour Holter monitoring revealed frequent ventricular premature beats. A transthoracic echocardiogram showed severe biventricular dilation and mild left ventricular (LV) dysfunction. Cardiac magnetic resonance (CMR) imaging confirmed these findings, showing moderate right ventricular (RV) systolic dysfunction with akinesia of the inferior and inferolateral walls. T2 hypersignal in the middle segment of the inferior inferior interventricular septum suggested myocardial edema. Extensive transmural late gadolinium enhancement was noted in the RV and LV walls. An implantable loop recorder was implanted. Three months later, the patient was admitted with palpitations, fever, and a positive SARS-CoV-2 test. Sustained ventricular tachycardia (VT) episodes were documented and managed with amiodarone and β-blockers. Follow-up CMR showed a slight improvement in LV ejection fraction and resolution of edema. A single-chamber implantable cardioverter-defibrillator (ICD) was implanted. Genetic testing for arrhythmogenic RV cardiomyopathy (ARVC) was negative, and family screening was normal. Two years later, pre-syncope episodes occurred, and ICD interrogation revealed nonsustained VT. The patient is awaiting VT ablation. This case highlights the diagnostic and therapeutic challenges of ARVC, particularly in differentiating it from myocarditis. The "hot-phase" presentation, vaccine association, and subsequent SARS-CoV-2 infection added complexity. CMR was crucial for diagnosis, and VT management required a combination of medical therapy and invasive procedures.
We discuss aspects related to the speciation of vanadium compounds (VCs) with salen-type ligands, as well as VIVO(acac)2 and VIVO(phen)2(SO4), namely the stability of their VIV and VV complexes in aqueous aerobic solutions at pH~7, and consequences on the study of toxicity, insulin mimetic and nuclease activity studies. We show that in these aerobic aqueous solutions VIV Schiff-base (SB) complexes of the salen-type are normally not stable to oxidation to VV and to hydrolysis of the ligand. VIVO(phen)2(SO4) and VIVO(acac)2 and are also not stable to oxidation, and a significant decomposition of these complexes occurs within the first 30 minutes after their dissolution. Therefore, when these VCs are used for in vitro or in vivo studies the active species is not known. Reduction of the salen SB to give amine compounds yields salan ligands which form much more stable complexes than the parent SB. When dissolved in non-degassed aqueous solutions at pH~7 the VIV-salan compounds oxidise to VV-salan complexes, but no hydrolysis is detected. At least with the cell lines tested these VCs are not toxic possibly because they do not enter the cells significantly. We emphasize that to understand if the VCs enter the cells or not is an important point to sort out in insulin-mimetic studies. In fact we also report some studies of nuclease activity of several salen and salan VCs, as well as of VIVO(acac)2 and VIVO(phen)2(SO4) with plasmid DNA. Many of these VCs show nuclease activity even in the absence of activating agents, so toxicity resulting from this may occur. We also study several parameters relevant for the nuclease activity of VCs, namely the nature and concentration of the buffer used.
A new trinuclear oxovanadium(V) complex with the anionic dmpp ligand (Hdmpp = 3-hydroxy-1,2-dimethyl-4-pyridinone), [V3O6(dmpp)3(H2O)](H2O)2, was isolated from the reaction of Hdmpp, KOH and sodium metavanadate at pH 4.5. The solid state structure of the [V3O6(H2O)(dmpp)3](H2O)2 complex, investigated by X-ray diffraction methods, was found to contain a cyclic trinuclear metal cluster. This complex crystallises in the monoclinic system: P21/n, a = 9.5324(7) Å, b = 16.4107(11) Å and c = 18.0638(12) Å, β = 91.1010(10)°, V = 2825.3(3) Å3, Z = 4 and R1(wR2) = 0.0704 (0.2025). Two of the vanadium atoms (V1 and V3) are six-coordinated, with distorted octahedral geometries, and the other one (V2) is five-coordinated with a distorted square pyramidal geometry. The cyclic V3O4 framework has one oxygen atom bridging two vanadium atoms in two V−O−V groups, V1−O4−V2 and V2−O5−V3, and two oxygens bridging the V1−V3 atoms, V1−O6−V3 and V1−O12−V3. IR data confirm the crystallographic results, showing the characteristic V=O band in the 973−935 cm−1 frequency range. This compound has three bands corresponding to V=O stretching, indicative of different chemical environments around the vanadium atoms in the solid state. The ES mass spectrum in aqueous solution displays an intense peak corresponding to the [V3O6(dmpp)3(H2O)+2H+]2+ fragment. 51V and 1H NMR spectroscopy were used to study this complex in aqueous solution. The dissolution of the crystalline [V3O6(dmpp)3(H2O)](H2O)2 compound in water, under aerobic conditions at pH 4.2, gave one intense broad signal at δ = −490 in the 51V NMR spectrum, which is attributed to a major species present in solution. The observation of only one 51V NMR signal, instead of the three expected from the different chemical environments of each vanadium atom present in the solid, is consistent with a fast (in the NMR timescale) dynamic equilibrium equalising their environments. This involves a fast exchange between O8, O10 and O12 as mono- or bifunctional oxygen atoms, as well as the H2O molecule, which acts in another fast equilibrium coordinating the vanadium atom that has a dmpp ligand with one bifunctional oxygen atom. The trinuclear oxovanadium(V) complex is relatively stable in water in the pH range 2.5−5.0. However, dissociation of the complex occurs at higher pH, leading to various hydrolysis products, which include mononuclear complex species with 1:1 and 1:2 metal-to-ligand stoichiometries, and monomeric and oligomeric species of free vanadium(V).
Several solution properties of complexes formed between the trivalent lanthanide ions (LnIII) and the macrocyclic ligand DOTP8-, including stability constants, protonation equilibria, and interactions of the LnDOTP5- complexes with alkali metal ions, have been examined by spectrophotometry, potentiometry, osmometry, and 1H, 31P, and 23Na NMR spectroscopy. Spectrophotometric competition experiments between DOTP and arsenazo III for complexation with the LnIII ions at pH 4 indicate that the thermodynamic stability constants (log KML) of LnDOTP5- range from 27.6 to 29.6 from LaIII to LuIII. The value for LaDOTP5- obtained by colorimetry (27.6) was supported by a competition experiment between DOTP and EDTA monitored by 1H NMR (27.1) and by a potentiometric competition titration between DTPA and DOTP (27.4). Potentiometric titrations of several LnDOTP5- complexes indicated that four protonation steps occur between pH 10 and 2; the protonation constants determined by potentiometry were consistent with 31P shift titrations of the LnDOTP5- complexes. Dissection of the 31P shifts of the heavy LnDOTP5- complexes (Tb → Tm) into contact and pseudocontact contributions showed that the latter dominated at all pH values. The smaller 31P shifts observed at lower pH for TmDOTP5- were partially due to relaxation of the chelate structure which occurred upon protonation. The 31P shifts of other LnDOTP5- complexes (Ln = Pr, Nd, Eu) showed a different pH-dependent behavior, with a change in chemical shift direction occurring after two protonation steps. This behavior was traced to a pH-dependent alteration of the contact shift at the phosphorus nuclei as these complexes were protonated. 23Na NMR studies of the interactions of TmDOTP5- with alkali and ammonium cations showed that Et4N+ and Me4N+ did not compete effectively with Na+ for the binding sites on TmDOTP5-, while K+ and NH4+ competed more effectively and Cs+ and Li+ less effectively. A 23Na shift of more than 400 ppm was observed at low Na+/TmDOTP5- ratios and high pH, indicating that Na+ was bound near the 4-fold symmetry axis of TmDOTP5- under these conditions. Osmolality measurements of chelate samples containing various amounts of Na+ indicated that at high Na+/TmDOTP5- ratios at least three Na+ ions were bound to TmDOTP5-. These ions showed a significantly smaller 23Na-bound shift, indicating they must bind to the chelate at sites further away from the 4-fold symmetry axis. Fully bound 23Na shifts and relaxation rate enhancements and binding constants for all NaxHyTmDOTP species were obtained by fitting the observed 23Na shift and relaxation data and the osmometric data, using a spreadsheet approach. This model successfully explained the 23Na shift and osmolality observed for the commercial reagent Na4HTmDOTP·3NaOAc (at 80 mM at pH 7.4).
The contribution of gluconeogenesis to hepatic glucose production (GP) was quantified after (2)H(2)O ingestion by Bayesian analysis of the position 2 and 5 (2)H-NMR signals (H2 and H5) of monoacetone glucose (MAG) derived from urinary acetaminophen glucuronide. Six controls and 10 kidney transplant (KTx) patients with cyclosporine A (CsA) immunosuppressant therapy were studied. Seven KTx patients were lean and euglycemic (BMI = 24.3 +/- 1.0 kg/m(2); fasting glucose = 4.7 +/- 0.1 mM) while three were obese and hyperglycemic (BMI = 30.5 +/- 0.7 kg/m(2); fasting glucose = 7.1 +/- 0.5 mM). For the 16 spectra analyzed, the mean coefficient of variation for the gluconeogenesis contribution was 10% +/- 5%. This uncertainty was associated with a mean signal-to-noise ratio (SNR) of 79:1 and 45:1 for the MAG H2 and H5 signals, respectively. For control subjects, gluconeogenesis contributed 54% +/- 7% of GP as determined by the mean and standard deviation (SD) of individual Bayesian analyses. For the lean/normoglycemic KTx subjects, the gluconeogenic contribution to GP was 62% +/- 7% (P = 0.06 vs. controls), while hyperglycemic/obese KTx patients had a gluconeogenic contribution of 68% +/- 3% (P < 0.005 vs. controls). These data suggest that in KTx patients, an increased gluconeogenic contribution to GP is strongly associated with obesity and hyperglycemia.
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