RESUMO
Zinc borates are very important industrial materials with applications that include fire retardants and preservatives in wood. In this work, we report the preparation of three novel zinc borates: [Zn(NH3)3B4O5(OH)4]·H2O (ZB1), Zn3(H2B3O7)2·2NH3·4H2O (ZB2), and [Zn(NH3)4][B4O5(OH)4]·4H2O (ZB3). The solid phases were characterized by elemental analysis, X-ray diffraction, infrared and Raman spectroscopy, scanning electron microscopy and thermal analysis. The crystal structures of ZB1 (monoclinic, Cc, a = 12.1972(8), b = 7.8314(5), c = 12.1441(8) Å and ß = 107.404(5)°) and ZB3 (orthorhombic, Pbca, a = 15.0796(9), b = 11.8853(5) and c = 16.7606(8) Å) were determined. They are novel neutral Zn-polyborate complexes [Zn(NH3)3B4O5(OH)4] hydrate and [Zn(NH3)4][B4O5(OH)4] tetrahydrate salt, respectively. The complete assignment of infrared and Raman spectra was performed theoretically using DFT calculations. For ZB2 (obtained as a polycrystalline phase), powder X-ray diffraction confirmed a single phase and allowed the determination of the unit cell parameters and lattice type (rhombohedral, a = 36.78076 (6), c = 12.20052 (3) Å) with an expected formula Zn3(H2B3O7)2·2NH3·4H2O suggesting that this compound is a complex triborate. Furthermore, a low-cost scalable synthetic procedure for ZB1 starting from zinc oxide and boric acid in ammonia solution with a high yield is also reported.
RESUMO
Within all the eukaryotic cells there is an important group of biomolecules that has been potentially related to signalling functions: myo-inositol phosphates (InsPs). In nature, the most abundant member of this family is the so called phytate (InsP6, L(12-)). The importance of the interaction of InsP6 with cations has been recognized during the last few years, and any attempt to know the function of this molecule in eukaryotic cells must include the fact that InsP6 will be strongly associated with simple inorganic or organic ammonium cations. In this work we expand on our earlier findings by studying the systems phen-phytate (phen = 1,10-phenanthroline) and Cu(ii)-phen-phytate. The structures of (Hphen)4(H8L)·7.5H2O and [Cu5(H7L)2(H2O)2(phen)5]·23H2O are presented. Solution studies of the binary and ternary systems were also performed by means of potentiometric titrations at 37.0 °C and 0.15 M ionic strength. The work was completed with a molecular modelling study. All this information is essential in the process of gaining reliable structural knowledge about the most important InsP6 species in the in vitro and in vivo experiments, and how these features modulate their probable biological functions.
RESUMO
Thirty-five isolates of Shigella sonnei from patients with diarrhoea in three geographic regions of Argentina were examined for genetic diversity by pulsed-field gel electrophoresis (PFGE) and plasmid profile. PFGE of XbaI and BlnI DNA digests confirmed the occurrence of outbreaks in two regions caused by two separate predominant clones of S. sonnei. The third region was characterized by three circulating clones, one of which was possibly associated with an outbreak. Similar plasmids were found in distinct clones and in one outbreak clone five different plasmid profiles were identified. Antimicrobial resistance of the isolates varied from fully susceptible to the agents tested, to resistance to cotrimoxazole, ampicillin and ciprofloxacin. Antibiotic resistance did not correlate with plasmid content. This information will form the basis for active surveillance of shigellosis in Argentina and elsewhere in the region through the PulseNet International Network.
Assuntos
Anti-Infecciosos/farmacologia , Surtos de Doenças/prevenção & controle , Resistência Microbiana a Medicamentos , Shigella sonnei , Argentina/epidemiologia , Eletroforese em Gel de Campo Pulsado , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Plasmídeos , Shigella sonnei/efeitos dos fármacos , Shigella sonnei/genética , Shigella sonnei/isolamento & purificaçãoRESUMO
Three copper(II)-rhenium(IV) bimetallic complexes of formula [ReCl(4)(mu-ox)Cu(phen)(2)] (1), [ReCl(4)(mu-ox)Cu(phen)(2)].CH(3)CN (2), and [ReCl(4)(mu-ox)Cu(terpy) (H(2)O)][ReCl(4)(mu-ox)Cu(terpy)(CH(3)CN)] (3) (ox = oxalate anion, phen = 1,10-phenanthroline, and terpy = 2,2':6,2"- terpyridine) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. Complex 1 crystallizes in the triclinic system, space group P(-1), with a = 9.776(2), b = 11.744(3), c = 14.183(3) A, alpha =102.09(2) degrees, beta = 109.42(2) degrees, gamma = 107.11(2) degrees, and Z = 2, whereas 2 and 3 crystallize in the monoclinic system, space groups P2(1)/n and P2(1)/c, respectively, with a = 12.837(3), b = 17.761(4), c = 12.914(3) A, beta = 91.32(2) degrees, and Z = 4 for 2, and a = 8.930(2), b = 18.543(4), c = 27.503(6) A, beta = 94.67(2) degrees, and Z = 4 for 3. The structures of 1 and 2 are made up of neutral [ReCl(4)(mu-ox)Cu(phen)(2)] bimetallic units. Re(IV) and Cu(II) metal ions exhibit distorted octahedral coordination geometries, being bridged by a bis(bidentate) oxalato ligand. The presence of acetonitrile molecules of crystallization in 2 causes a somewhat greater separation between the bimetallic complexes and a different packing of these units in the crystal structure with respect to 1. The copper-rhenium separation across oxalato is 5.628(2) in 1 and 5.649(3) A in 2. The structure of 3 is made up of two different and neutral bimetallic units, [ReCl(4)(mu-ox)Cu(terpy)(H(2)O)] and [ReCl(4)(mu-ox)Cu(terpy)(CH(3)CN)]. In the first one, the oxalate group behaves as a bis(bidentate) ligand occupying one equatorial and one axial position in the elongated octahedral environment of Cu(II). The water molecule is axially coordinated. In the second one, the oxalate group behaves as a bidentate/monodentate ligand occupying the axial position in the square pyramidal environment of Cu(II). The acetonitrile molecule occupies a basal coordination position around the copper atom. These units are arranged in such a way that a chlorine atom of the first unit (Cl(1)) points toward the copper atom (Cu(2))of the second one (3.077(2) A for Cl(1)(.)Cu(2)), forming a tetranuclear species. The copper-rhenium separation across bis(didentate) oxalato is 5.504(3) A, whereas that through bidentate/monodentate oxalato is 5.436(2) A. The magnetic behavior of 2 and 3 has been investigated over the temperature range 1.8-300 K. A very weak and nearly identical antiferromagnetic coupling between Re(IV) and Cu(II) through bis(bidentate) oxalato occurs in 2 (J = -0.90 cm(-1)) and 3 (J = -0.83 cm(-1)); it is ferromagnetic in 3 through both the bidentate-monodentate oxalato (J = +5.60 cm(-1)) and the chloro (J = +0.70 cm(-1)) bridges.
RESUMO
Trichlorooxo[1,3-propanediylbis(diphenylphosphine)-P,P ']rhenium(V), [ReCl(3)O(C(27)H(26)P(2))], crystallizes with four formula units per unit cell. The crystal structure consists of neutral complexes of [ReOCl(3)(dppp)] [dppp is 1,3-bis(diphenylphosphino)propane] packed by H.pi-ring interactions. The Re atom is octahedrally coordinated to the oxo anion, three Cl atoms and two P atoms from the dppp ligand. The six-membered ring formed by the bidentate dppp ligand and the rhenium metal centre is in a chair conformation. The title compound is an intermediate in the synthesis of bis(dppp) complexes of rhenium.
Assuntos
Compostos Organometálicos/química , Cristalografia por Raios X , Modelos Moleculares , Conformação MolecularRESUMO
A study of 99mTc-adenosine-5'-diphosphate (99mTc-ADP) as a radiopharmaceutical for tumour diagnosis is presented. Two different labelling methods, using SnCl2 in alkaline solution and Zn as reducing agents, were developed. Reduction with Sn(II) alkaline solution was the selected method because a lower concentration of ADP (0.5 mg/mL) could be used and a higher radiochemical yield was achieved. A labelled molecule with a radiochemical purity higher than 95%, in vitro stability of at least 6 hours and an over all negative charge was obtained Biodistribution studies carried out in normal mice and rats revealed rapid urinary excretion and no specific accumulation of activity in any other particular organ. This behaviour was similar to that reported for 99mTc-adenosine-5'-triphosphate (99mTc-ATP). Rapid blood clearance, that could be fitted to a bicompartimental model, was also verified. No evidence of in vivo instability was observed. Studies in mice and rats bearing spontaneous mammary adenocarcinomas were performed and the results were compared to those from the 99mTc-ATP studies. Although the tumour models used were not the same, the incorporation of both labelled compounds was very similar. Radioactivity uptake in the tumour and the tumour-to-blood ratio were not notably high. However, a significant increment was observed in the tumour-to-muscle ratio (1.0 +/- 0.2 at 30 minutes to 2.7 +/- 0.4 at 240 minutes). Whole-body autoradiography enabled tumour visualization. Further investigations, including scintigraphic imaging, must be carried to complete the clinical evaluation of 99mTc-ADP as a tumour seeking agent.
Assuntos
Difosfato de Adenosina/análogos & derivados , Neoplasias Experimentais/diagnóstico por imagem , Compostos de Organotecnécio , Compostos Radiofarmacêuticos , Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma/metabolismo , Difosfato de Adenosina/sangue , Difosfato de Adenosina/química , Difosfato de Adenosina/farmacocinética , Difosfato de Adenosina/urina , Trifosfato de Adenosina/química , Álcalis/química , Animais , Feminino , Masculino , Neoplasias Mamárias Experimentais/diagnóstico por imagem , Neoplasias Mamárias Experimentais/metabolismo , Camundongos , Camundongos Endogâmicos C3H , Músculo Esquelético/metabolismo , Neoplasias Experimentais/metabolismo , Compostos de Organotecnécio/sangue , Compostos de Organotecnécio/química , Compostos de Organotecnécio/farmacocinética , Compostos de Organotecnécio/urina , Oxirredução , Cintilografia , Compostos Radiofarmacêuticos/sangue , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/urina , Ratos , Ratos Wistar , Compostos de Estanho/química , Distribuição Tecidual , Zinco/químicaRESUMO
We studied retrospectively the clinical records of 291 hospital patients with liver cirrhosis, 95% of which was alcohol related. Within this group, 114 patients presented 155 episodes of infection in 144 separate hospital admissions. In a previous communication, we pointed out that although infection was the fourth cause of admission, it was the main cause of death in this group. The main incidence of infection was among the female group. The most common infections episodes were respiratory and bacterial spontaneous peritonitis (BSP). On admission, 57% of the patients were diagnosed as belonging to the C Child group; 38% presented sepsis and 22% were hospitalary infections. The most frequent infections were respiratory and BSP. We obtained bacteriologic documentation in 55% of the episodes with prevalence of Gram negative bacilli (E. coli), with high relative frequency of neumoccocus. The most frequent complications were related to hepatic insufficiency. Global death rate was 27.1%, while nosocomial death rates were 42.1% and 40.9% for patients with Child C. We observed the highest incidence of mortality in patients with SBP and non localized bacteriemia. Survival rates were 42% for 2 years and 18% for 5 years. In summary, we stress the relevancy of checking the presence of infection systematically in every cirrhotic patient with encephalopathy and/or renal insufficiency without justifiable cause.
Assuntos
Infecções Bacterianas/epidemiologia , Infecção Hospitalar/epidemiologia , Cirrose Hepática Alcoólica/complicações , Adulto , Distribuição por Idade , Idoso , Infecções Bacterianas/mortalidade , Infecção Hospitalar/mortalidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Peritonite/epidemiologia , Infecções Respiratórias/epidemiologia , Estudos Retrospectivos , Distribuição por SexoRESUMO
We studied retrospectively the clinical records of 291 hospital patients with liver cirrhosis, 95
of which was alcohol related. Within this group, 114 patients presented 155 episodes of infection in 144 separate hospital admissions. In a previous communication, we pointed out that although infection was the fourth cause of admission, it was the main cause of death in this group. The main incidence of infection was among the female group. The most common infections episodes were respiratory and bacterial spontaneous peritonitis (BSP). On admission, 57
of the patients were diagnosed as belonging to the C Child group; 38
presented sepsis and 22
were hospitalary infections. The most frequent infections were respiratory and BSP. We obtained bacteriologic documentation in 55
of the episodes with prevalence of Gram negative bacilli (E. coli), with high relative frequency of neumoccocus. The most frequent complications were related to hepatic insufficiency. Global death rate was 27.1
, while nosocomial death rates were 42.1
and 40.9
for patients with Child C. We observed the highest incidence of mortality in patients with SBP and non localized bacteriemia. Survival rates were 42
for 2 years and 18
for 5 years. In summary, we stress the relevancy of checking the presence of infection systematically in every cirrhotic patient with encephalopathy and/or renal insufficiency without justifiable cause.