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Biomedical subjects

M Verdaguer

Publications and source records attributed to M Verdaguer.

At least 19 recordsLinked to original sources

[Pneumoperitoneum and pneumomediastinum complicating non-invasive ventilation].

INTRODUCTION: Pneumoperitoneum is known to be a rare complication of invasive mechanical ventilation. However it has not previously been described as a consequence of non-invasive ventilation. CASE REPORT: The authors report a case of pneumoperitoneum associated with pneumomediastinum occurring in a 64-year-old patient treated for 3 years with bilevel ventilation via a nasal mask (expiratory pressure = 9 cm H2O, inspiratory pressure = 15 cm H2O) for obesity hypoventilation syndrome. Respiratory and gastroenterological investigations did not demonstrate a cause for this complication which resolved spontaneously following the cessation of ventilation. Nine months later, clinical deterioration and a worsening of blood gas parameters led to a recommencement of non-invasive mechanical ventilation at the same levels as previously. Over two years of follow up there have been no clinical or radiological signs of a recurrence of pneumomediastinum or pneumoperitoneum. CONCLUSION: In the absence of any other explanation, barotrauma due to nasal ventilation appears to be the most likely explanation for this complication.

Humans↗

[Angioplasty of intra-stent restenosis of a saphenous graft complicated by massive embolism].

The main risk of angioplasty of saphenous vein aortocoronary bypass grafts is myocardial infarction by distal embolism, explaining the introduction of systems of distal protection with encouraging results. Although embolism of an atheromatous stenosis is classical, that of intra-stent restenosis is exceptional. The authors report a very unusual case of atheromatous and/or thrombotic embolism occurring during angioplasty of an intra-stent restenosis which was recovered by a micropore filter system.

Aged↗

Local magnetic susceptibility of the positive muon in the quasi-one-dimensional S=1/2 antiferromagnet dichlorobis (pyridine) copper (II).

We report muon spin rotation measurements of the local magnetic susceptibility around a positive muon in the paramagnetic state of the quasi-one-dimensional spin 1/2 antiferromagnet dichlorobis (pyridine) copper (II). Signals from three distinct sites are resolved and have a temperature dependent frequency shift which is significantly different than the magnetic susceptibility. This difference is attributed to a muon induced perturbation of the spin 1/2 chain. The obtained frequency shifts are compared with transfer matrix density-matrix renormalization-group numerical simulations.

Journal Article↗

Photoinduced ferrimagnetic systems in Prussian blue analogues C(I)xCo4[Fe(CN)6]y (C(I) = alkali cation). 3. Control of the photo- and thermally induced electron transfer by the [Fe(CN)6] vacancies in cesium derivatives.

We synthesized a series of CoFe Prussian blue analogues along which we tuned the amount of cesium cations inserted in the tetrahedral sites of the structure. Structure and electronic structure have been investigated, combining XANES, infrared spectroscopy, powder X-ray diffraction experiments, and magnetization measurements. The change of the magnetization induced by light along the series shows that the efficiency of the photoinduced magnetization, evidenced a few years ago in similar compounds by Hashimoto et al. (Sato, O.; Iyoda, T.; Fujishima, A.; Hashimoto, K. Science 1996, 272, 704-705; Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Electrochem. Soc. 1997, 144, L11-L13; Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Phys. Chem. B 1997, 101, 3903-3905; Einaga, Y.; Ohkoshi, S.-I.; Sato, O.; Fujishima, A.; Hashimoto, K. Chem. Lett. 1998, 585-586; and Sato, O.; Einaga, Y.; Fujishima, A.; Hashimoto, K. Inorg. Chem. 1999, 38, 4405-4412), depends on a compromise between the number of excitable diamagnetic pairs and the amount of [Fe(CN)6] vacancies giving the network flexibility. Besides the efficiency of the photoinduced process, the amount of [Fe(CN)6] vacancies also controls a thermally induced electron transfer.

Journal Article↗

Photoinduced ferrimagnetic systems in Prussian blue analogues C(I)xCo4[Fe(CN)6]y (C(I) = alkali cation). 4. Characterization of the ferrimagnetism of the photoinduced metastable state in Rb1.8Co4[Fe(CN)6]3.3-13H2O by K edges X-ray magnetic circular dichroism.

In Part 2 of this work, the electronic and local structure of the photoinduced metastable magnetic state of the Prussian blue analogue Rb1.8Co4[Fe(CN)6]3.3-13H2O were characterized. To determine directly the relative orientation of the magnetic moments of Co(II) and Fe(III) ions in the metastable state, and the nature of the exchange interaction between them, we performed X-ray magnetic circular dichroism (XMCD) experiments at the cobalt and iron K edges. We present the first direct experimental evidence of the antiferromagnetic interaction between the cobalt and the iron ions, leading to the ferrimagnetism of the photoinduced metastable state.

Journal Article↗

Exchange coupling in cyano-bridged homodinuclear Cu(II) and Ni(II) complexes: synthesis, structure, magnetism, and density functional theoretical study.

The synthesis and structural characterization of several new cyano-bridged copper(II) and nickel(II) homodinuclear complexes is presented. The measure of magnetic properties for these complexes is complemented with a computational study of the exchange coupling for several model structures representing this family of compounds. The influence of several factors on the coupling constant has been examined, coordination position occupied by the bridging ligand, distortions of the coordination environment, and relative disposition of the cyanide ion with respect to the M-M vector. Comparison of experimental and calculated coupling constants allows for the rationalization of the most relevant features of the exchange interaction between two identical metal ions through a cyano bridge.

Journal Article↗

Rational design of three-dimensional (3D) optically active molecule-based magnets: synthesis, structure, optical and magnetic properties of ([Ru(bpy)3](2+), ClO4(-), [Mn(II) Cr(III)(ox)3](-))n and ([Ru(bpy)2ppy](+), [M(II)Cr(III)(ox)3](-))n, with M(II) = Mn(II), Ni(II). X-ray structure of ([deltaRu(bpy)3](2+), ClO4(-), [deltaMn(II)DeltaCr(III)(ox)3](-))n and ([lambdaRu(bpy)2ppy)](+), [lambdaMn(II)lambdaCr(III)(ox)3](-))n.

To elucidate the relation between structural and magnetic properties, we have synthesized molecular materials having both Cotton effects and a ferromagnetic long range order. Such optically active 3D molecule-based magnets were rationally designed using the enantioselective template effect of optically active cations, namely Delta or Lambda [Ru(bpy)3, ClO4](+) or Delta or Lambda [Ru(bpy)3ppy](+) (bpy = bipyridine; ppy = phenylpyridine). Such cations are able to template the formation of optically active 3D anionic networks in which transition metal ions (Cr-Mn) and (Cr-Ni) are connected by oxalate ligands (ox). Following this strategy, we described the synthesis of ([Ru(bpy)3](2+), ClO4(-), [Mn(II)Cr(III)(ox)3](-))n and ([Ru(bpy)2ppy](+), [M(II)Cr(III)(ox)3](-))n with M(II) = Mn(II), Ni(II) in their optically active forms. In these 3D networks, all of the metallic centers have the same configuration, Delta or Lambda, as the template cation. We have determined the structure of ([DeltaRu(bpy)3][ClO4][DeltaMnDeltaCr(ox)3])n and ([LambdaRu(bpy)2ppy](+), [LambdaMn(II)LambdaCr(III)(ox)3](-))n by X-ray diffraction studies. These optically active networks show the Cotton effect and long-range ferromagnetic order at low temperatures. The magnetic circular dichroism of ([Ru(bpy)3](2+), ClO4(-), [Mn(II)Cr(III)(ox)3](-))n at 2 K is reported.

Journal Article↗

[Fe(Phen)(CN)4]-: a versatile building block for the design of heterometallic systems. Crystal structures and magnetic properties of PPh4[Fe(Phen)(CN)4]*2H2O and [[Fe(Phen)(CN)4]2M(H2O)2]*4H2O [Phen = 1,10-phenanthroline; M = Mn(II) and Zn(II)].

The mononuclear PPh4[Fe(phen)(CN)4]*2H2O (1) complex and the cyanide-bridged bimetallic [[Fe(phen)(CN)4]2M(H2O)2]*4H2O compounds [M = Mn(II) (2) and Zn(II) (3); phen = 1,10-phenanthroline; PPh4 = tetraphenylphosphonium cation] have been synthesized and structurally and magnetically characterized. Complex 1 crystallizes in the monoclinic system, space group P2(1)/c, with a = 9.364(4) A, b = 27.472(5) A, c = 14.301(3) A, beta = 97.68(2) degrees, and Z = 4. Complexes 2 and 3 are isostructural and they crystallize in the monoclinic system, space group P2(1)/n, with a = 7.5292(4) A, b = 15.6000(10) A, c = 15.4081(9) A, beta = 93.552(2) degrees, and Z = 2 for 2 and a = 7.440(1) A, b = 15.569(3) A, c = 15.344(6) A, beta = 93.63(2) degrees, and Z = 2 for 3. The structure of complex 1 is made up of mononuclear [Fe(phen)(CN)4]- anions, tetraphenyphosphonium cations, and water molecules of crystallization. The iron(III) is hexacoordinate with two nitrogen atoms of a chelating phen (2.018(6) and 2.021(6) A for Fe-N) and four carbon atoms of four terminal cyanide groups (Fe-C bond lengths varying in the range 1.906(8)-1.95(1) A) building a distorted octahedron around the metal atom. The structure of complexes 2 and 3 consists of neutral double zigzag chains of formula [[Fe(phen)(CN)4]2M(H2O)2] and crystallization water molecules. The [Fe(phen)(CN)4]- entity of 1 is present in 2 and 3 acting as a bridging ligand toward M(H2O)2 units [M = Mn(II) (2) and Zn(II) (3)] through two cyanide groups in cis positions, the other two cyanide remaining terminal. Two water molecules in trans positions and four cyanide-nitrogen atoms from four [Fe(phen)(CN)4]- units build a distorted octahedral surrounding Mn(II) (2) and Zn(II) (3). The M-O bond lengths are 2.185(3) (2) and 2.105(3) A (3), whereas the M-N bond distances vary in the ranges 2.210(3)-2.258(3) A (2) and 2.112(3)-2.186(3) A (3). The structure of the [Fe(phen)(CN)4]- complex ligand in 2 and 3 is as in 1. The shorter intrachain Fe-M distances through bridging cyano are 5.245(5) and 5.208(5) A in 2 and 5.187(1) and 5.132(1) A in 3. The magnetic properties of 1-3 have been investigated in the temperature range 2.0-300 K. Complex 1 is a low-spin iron(III) complex with an appreciable orbital contribution. The magnetic properties of 3 correspond to the sum of two magnetically isolated spin triplets, the magnetic coupling between the low-spin iron(III) centers through the -CN-Zn-NC- bridging skeleton (iron-iron separation larger than 10.2 A) being negligible. More interestingly, 2 exhibits one-dimensional ferrimagnetic behavior due to the noncompensation of the local interacting spins (S(Mn) = 5/2 and S(Fe) = 1/2) which interact antiferromagnetically through bridging cyano groups. A comparison between the magnetic properties of the isostructural compounds 2 and 3 allow us to check the antiferromagnetic coupling in 2.

Journal Article↗

Optically active molecule-based magnets: enantioselective self-assembling, optical, and magnetic properties.

In this short communication we describe the synthesis and the optical and magnetic properties of optically active three dimensional (3D) bimetallic [Cr-Mn] networks [[Delta Cr(III) Delta Mn(II)(ox)(3)][Delta Ru(II)(bpy)(3)]ClO(4)](n)1 - Delta, [[Lambda Cr(III)Lambda Mn(II)(ox)(3)][Lambda Ru(II) (bpy)(3)]ClO(4)](n) 1 - Lambda and [[Delta Cr(III)Delta Mn(II)(ox)(3)][Delta Ru(II)(bpy)(2)p p y]](n) 2 - Delta,[[Lambda Cr(III)Lambda Mn(II)(ox)(3)][Lambda Ru(II)(bpy)(2)ppy]](n) 2 - Lambda (ox = oxalate, bpy = bipyridine, ppy = phenyl-pyridine).

Journal Article↗

Crystal structure and magnetic properties of an octacyanometalate-based three-dimensional tungstate(V)-manganese(II) bimetallic assembly.

A single crystal of the title compound [MnII6(H2O)9[W(V)(CN)8]4 x 13H2O]n was synthesized in a hot aqueous solution containing octacyanotungstate, Na3[W(CN)8] x 3H2O, and Mn(ClO4)2 x 6H2O. The compound crystallized in the monoclinic system, space group P2(1)/c with cell constants a = 15.438(2) A, b = 14.691(2) A, c = 33.046(2) A, beta = 94.832(9) degrees, and Z = 4. The crystal consists of a W(V)-CN-MnII linked three-dimensional network [[MnII(H2O)]3[MnII(H2O)2]3[W(V)(CN)8]4]n and H2O molecules as crystal solvates. There are two kinds of W sites: one is close to a dodecahedron geometry with six bridging and two terminal CN ligands; the other is close to a bicapped trigonal prism with seven bridging and one terminal CN ligands. The field-cooled magnetization measurement showed that the compound exhibits a spontaneous magnetization below Tc = 54 K. Further magnetization measurements on the field dependence reveal it to be a ferrimagnet where all of the MnII ions are antiparallel to all the W(V) ions.

Journal Article↗

[Aneurysm of the sinus of Valsalva. Apropos of a case of right intra-atrial rupture].

An unusual systolo-diastolic heart murmur was discovered fortuitously in a 39-year-old man undergoing a routine check-up. Transesophageal echocardiography gave the diagnosis of Valsalva sinus aneurysm ruptured into the right atrium. Cardiac surgery was successful. We reviewed the literature on this unusual condition, focusing on the pathophysiological, clinical, diagnostic and therapeutic aspects. Transesophageal echocardiography provides the diagnosis.

Adult↗

[Immediate collateral coronary circulation after a methylergometrin test].

The development of a collateral coronary circulation has been well studied by angiography in two main clinical situations: myocardial infarction (by durable coronary occlusion) and angina (due to significant coronary artery stenosis), but only rarely in spastic angina. The authors report the case of severe spasm at the site of non-significant stenosis after a methylergometrine test, with immediate contro-lateral collateral circulation in a patient with a short history of spastic angina without myocardial infarction. This observation demonstrates that collateral circulation may develop very rapidly in spastic angina (without basal ischaemia in the absence of significant coronary stenosis), because this patient only had seven ten-minute episodes of clinical ischaemia. As collateral circulation may mask clinical and electrical signs in spastic angina, this case suggests that angiographic control should be systematic during the methylergometrine test.

Collateral Circulation↗

[CREST syndrome presenting as pulmonary hypertension].

The authors report the case of a 62-year-old patient complaining of recent onset of disabling breathlessness on exertion, and presenting clinical signs of previously undiagnosed scleroderma. Echocardiography revealed a diagnosis of precapillary pulmonary hypertension (74/14 mmHg) (PHT), with no pulmonary cause revealed by pulmonary ventilation-perfusion scintigraphy or by thoracic fine section computed tomography. The diagnosis of PHT in the context of circumscribed scleroderma was confirmed by x-rays of the hands, capillaroscopy, oesophageal investigations and positive anticentromere antinuclear antibodies. The clinical course was marked by rapid deterioration of the symptoms, requiring treatment with prostacyclin by continuous intravenous infusion. The appearance of PHT in a context of circumscribed scleroderma, usually a relatively benign disease, is a rare, late event, exceptionally revealing the disease, as in this case, and indicating a very unfavourable prognosis.

Antibodies, Antinuclear↗

X-ray absorption spectroscopy of carbonyl basket handle Fe(II) porphyrins: the distortion of the tetrapyrrolic macrocycle.

The distortion of the tetrapyrrolic macrocycle, the Fe-C-O bond angle and the Fe local electronic structure of carbonyl basket-handle Fe2+ porphyrins as a function of the basket-handle chain length have been studied by X-ray absorption near edge structure (XANES) spectroscopy, both in the solid state and in toluene solution. The Fe-C-O bond angle has been found to be linear in all compounds while the increasing distortion of the macrocycle with shortening of the chain length is indicated by the multiple scattering resonance in the heme plane appearing at 22 eV in the XANES spectrum.

Iron↗

Influence of chronic treatment with iopanoic acid on thyroxine metabolism in the newborn rat.

Parameters of the peripheral metabolism of thyroxine (T4) were studied in the early postnatal period. Iopanoic acid (IOP) was administered to newborn rats that were either euthyroid or rendered hypothyroid in utero by propylthiouracil (PTU) or methimazole (MMI) administration to the mothers during gestation and injected with thyroxine on postnatal days 6 and 7. In euthyroid newborn rats given IOP from postnatal day 6, the plasma T4 level increased (+50%) while the plasma 3,3',5'-triiodothyronine (T3) level slightly decreased (-18%). Peripheral deiodination of T4 was also reduced (about -50%) as estimated by thyroid 125I uptake after injection of 125I (3'-5')L-T4. In the newborn rats rendered hypothyroid in utero and given T4 on postnatal days 6 and 7, IOP treatment started on day 4 decreased the constant rate of elimination (-50%), the distribution volume (-43%) and the metabolic clearance (-74%) of plasma T4. The results were the same in PTU- and MMI-treated newborn rats. The differences between newborn and adult animals under IOP treatment are discussed.

Animals↗