Dynamic exercise changes in venous pressure and liver stiffness in Fontan patients: effects of Treprostinil.

BACKGROUND: Systemic venous hypertension and low cardiac output are believed to be important mediators of liver injury after the Fontan procedure. Pulmonary vasodilators have the potential to improve such haemodynamics. The aim of this study was to assess the acute effects of exercise on liver stiffness and venous pressures and to assess the impact of inhaled Treprostinil on this response. METHODS: In this prospective, double-blind, placebo-controlled, crossover trial, 14 patients with a Fontan circulation were randomised to inhalation of placebo and Treprostinil. Incremental and constant work rate exercise tests were performed to assess the effect of Treprostinil on exercise tolerance. Venous pressures were measured throughout and liver stiffness at rest and immediately after peak exercise. RESULTS: Mean age was 27.8 ± 7.9 years and 66% were females. Exercise acutely increased liver stiffness by 30% (mean shear wave speed: 2.38 ± 0.71 versus 2.89 ± 0.51 ms, p = 0.02). Peripheral venous pressures increased acutely during both incremental (12.1 ± 2.4 versus 22.6 ± 8.0 mmHg, p < 0.001) and constant work rate exercise (12.5 ± 2.5 versus 23.4 ± 5.2 mmHg, p < 0.001). Overall, Treprostinil failed to attenuate exercise-induced increases in liver stiffness. Compared with placebo, Treprostinil did not significantly impact venous pressure responses, VO2peak, nor exercise endurance times. CONCLUSIONS: Peripheral venous pressure increased acutely during exercise by an average of 88% above baseline and was not altered by administration of inhaled Treprostinil. Liver stiffness measured immediately post-exercise increased acutely by an average of 30%, with no attenuation following Treprostinil inhalation.

A Pilot Study of School-Based Comprehensive Cardiovascular Screening in Middle School Children.

Although recommended, most children are not routinely screened for lipid abnormalities and diabetes. We report a pilot of universal screening for diabetes, lipid abnormalities, and hypertension in the middle-school setting. Of 45 children screened, 34.8% had lipid or hemoglobin A1c abnormalities and 2 had hemoglobin A1c values in the diabetes range.

Effects of Remote Ligand Substituents on the Structures, Spectroscopic, and Magnetic Properties of Two-Coordinate Transition-Metal Thiolate Complexes.

The first-row transition-metal(II) dithiolates M(SAriPr4)2 [AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2; M = Cr (1), Mn (3), Fe (4), Co (5), Ni (6), and Zn (7)] and Cr(SArMe6)2 [2; ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2] and the ligand-transfer reagent (NaSAriPr4)2 (8) are described. In contrast to their M(SAriPr6)2 (M = Cr, Mn, Fe, Co, Ni, and Zn; AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) congeners, which differ from 1 and 3-6 in having p-isopropyl groups on the flanking aryl rings of the terphenyl substituents, compounds 1 and 4-6 display highly bent coordination geometries with S-M-S angles of 109.802(2)° (1), 120.2828(3)° (4), 91.730(3)° (5), and 92.68(2)° (6) as well as relatively close metal-flanking aryl ring η6 interactions with metal-centroid distances of 2.11477(6) Å (1), 1.97188(3) Å (2), 2.15269(6) Å (4), 1.62058(9) Å (5), and 1.724(8) Å (6). However, the d5 (Mn) and d10 (Zn) complexes 3 and 7 display linear or near-linear coordination with no close metal-ligand distances. The nonlinear geometries of 1 and 4-6 also contrast with those of their AriPr4-substituted alkoxo and amido congeners, which have strictly linear coordination. Complexes 1-7 were synthesized by the reaction of the lithium or sodium thiolate salt with the metal dihalide or, in the case of 3, by the reaction of the thiol with the amido complex Mn[N(SiMe3)2]2. All compounds were characterized by electronic spectroscopy, X-ray crystallography, and magnetic measurements using Evans' method and SQUID magnetometry. It was concluded that, despite the large bulk of the AriPr4 substituents, the absence of p-isopropyl groups on the flanking rings of the ligand permits close secondary metal-flanking ring distances. The compounds are characterized by more intense colors and display magnetic moments that are generally lower than the spin-only values, in agreement with the covalent character of the close metal-flanking ring η6 interactions.

Identification of cellular targets of a series of boron heterocycles using TIPA II-A sensitive target identification platform.

One of the hurdles in the discovery of antibiotics is the difficulty of linking antibacterial compounds to their cellular targets. Our laboratory has employed a genome-wide approach of over-expressing essential genes in order to identify cellular targets of antibacterial inhibitors. Our objective in this project was to develop and validate a more sensitive disk diffusion based platform of target identification (Target Identification Platform for Antibacterials version 2; TIPA II) using a collection of cell clones in an Escherichia coli mutant (AS19) host with increased outer membrane permeability. Five known antibiotics/inhibitors and 28 boron heterocycles were tested by TIPA II assay, in conjunction with the original assay TIPA. The TIPA II was more sensitive than TIPA because eight boron heterocycles previously found to be inactive to AG1 cells in TIPA assays exhibited activity to AS19 cells. For 15 boron heterocycles, resistant colonies were observed within the zones of inhibition only on the inducing plates in TIPA II assays. DNA sequencing confirmed that resistant clones harbor plasmids with fabI gene as insert, indicating that these boron heterocycles all target enoyl ACP reductase. Additionally, cell-based assays and dose response curved obtained indicated that for two boron heterocycle inhibitors, the fabI cell clone in AG1 (wild-type) host cells exhibited at least 11 fold more resistance under induced conditions than under non-induced conditions. Moreover, TIPA II also identified cellular targets of known antibacterial inhibitors triclosan, phosphomycin, trimethoprim, diazaborine and thiolactomycin, further validating the utility of the new system.

The Instability of Ni{N(SiMe3 )2 }2 : A Fifty Year Old Transition Metal Silylamide Mystery.

The characterization of the unstable Ni(II) bis(silylamide) Ni{N(SiMe3 )2 }2 (1), its THF complex Ni{N(SiMe3 )2 }2 (THF) (2), and the stable bis(pyridine) derivative trans-Ni{N(SiMe3 )2 }2 (py)2 (3), is described. Both 1 and 2 decompose at ca. 25 °C to a tetrameric Ni(I) species, [Ni{N(SiMe3 )2 }]4 (4), also obtainable from LiN(SiMe3 )2 and NiCl2 (DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of Ni(II) to Ni(I) and the stabilization of 4 through dispersion forces.

Terphenyl complexes of molybdenum and tungsten with quadruple metal-metal bonds and bridging carboxylate ligands.

Mono- and bis-terphenyl complexes of molybdenum and tungsten with general composition M2(Ar')(O2CR)3 and M2(Ar')2(O2CR)2, respectively (Ar' = terphenyl ligand), that contain carboxylate groups bridging the quadruply bonded metal atoms, have been prepared and structurally characterized. The new compounds stem from the reactions of the dimetal tetracarboxylates, M2(O2CR)4 (M = Mo, R = H, Me, CF3; M = W, R = CF3) with the lithium salts of the appropriate terphenyl groups (Ar' = Ar(Xyl2), Ar(Mes2), Ar(Dipp2), and Ar(Trip2)). Substitution of one bidentate carboxylate by a monodentate terphenyl forms a M-C σ bond and creates a coordination unsaturation at the other metal atom. Hence in M2(Ar')2(O2CR)2 complexes the two metal atoms have formally a low coordination number and an also low electron count. However, the unsaturation seems to be compensated by a weak M-C(arene) bonding interaction that implicates one of the aryl substituents of the terphenyl central aryl ring, as revealed by X-ray studies performed with some of these complexes and by theoretical calculations.

Synthesis, characterization, and antibacterial activity of structurally complex 2-acylated 2,3,1-benzodiazaborines and related compounds.

A set of 2-acylated 2,3,1-benzodiazaborines and some related boron heterocycles were synthesized, characterized, and tested for antibacterial activity against Escherichia coli and Mycobacterium smegmatis. By high-field solution NMR, the heretofore unknown class of 2-acyl-1-hydroxy-2,3,1-diazaborines has been found to be able to exist in several interconvertable structural forms along a continuum comprised of an open hydrazone a, a monomeric B-hydroxy diazaborine b, and an anhydro dimer c. X-Ray crystallography of one of the anhydro dimers, 17c, revealed it to have an unprecedented structure featuring a double intramolecular O→B chelation. The crystal structure of another compound, 37, showed it to be based on a new pentacyclic B heterocycle framework. Nine compounds were found to possess activities against E. coli, and two others were active against M. smegmatis. The finding that these two contain isoniazid covalently embedded in their structures suggests that they might possibly be acting as prodrugs of this well-known antituberculosis agent in vivo.

Bleeding and thrombotic risk in pregnant women with Fontan physiology.

BACKGROUND/OBJECTIVES: Pregnancy may potentiate the inherent hypercoagulability of the Fontan circulation, thereby amplifying adverse events. This study sought to evaluate thrombosis and bleeding risk in pregnant women with a Fontan. METHODS: We performed a retrospective observational cohort study across 13 international centres and recorded data on thrombotic and bleeding events, antithrombotic therapies and pre-pregnancy thrombotic risk factors. RESULTS: We analysed 84 women with Fontan physiology undergoing 108 pregnancies, average gestation 33±5 weeks. The most common antithrombotic therapy in pregnancy was aspirin (ASA, 47 pregnancies (43.5%)). Heparin (unfractionated (UFH) or low molecular weight (LMWH)) was prescribed in 32 pregnancies (30%) and vitamin K antagonist (VKA) in 10 pregnancies (9%). Three pregnancies were complicated by thrombotic events (2.8%). Thirty-eight pregnancies (35%) were complicated by bleeding, of which 5 (13%) were severe. Most bleeds were obstetric, occurring antepartum (45%) and postpartum (42%). The use of therapeutic heparin (OR 15.6, 95% CI 1.88 to 129, p=0.006), VKA (OR 11.7, 95% CI 1.06 to 130, p=0.032) or any combination of anticoagulation medication (OR 13.0, 95% CI 1.13 to 150, p=0.032) were significantly associated with bleeding events, while ASA (OR 5.41, 95% CI 0.73 to 40.4, p=0.067) and prophylactic heparin were not (OR 4.68, 95% CI 0.488 to 44.9, p=0.096). CONCLUSIONS: Current antithrombotic strategies appear effective at attenuating thrombotic risk in pregnant women with a Fontan. However, this comes with high (>30%) bleeding risk, of which 13% are life threatening. Achieving haemostatic balance is challenging in pregnant women with a Fontan, necessitating individualised risk-adjusted counselling and therapeutic approaches that are monitored during the course of pregnancy.

Quadruply bonded dimolybdenum complexes with highly unusual geometries and vacant coordination sites.

New quadruply bonded dimolybdenum complexes of the terphenyl ligand Ar(Xyl(2)) (Ar(Xyl(2)) = C(6)H(3)-2,6-(C(6)H(3)-2,6-Me(2))(2)) have been prepared and structurally characterized. The steric hindrance exerted by the Ar(Xyl(2)) groups causes the Mo atoms to feature unsaturated four-coordinate structures and a formal fourteen-electron count.