Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 23
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
J Immunol ; 183(12): 8015-25, 2009 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-19933850

RESUMO

Patients chronically infected with Trypanosoma cruzi develop chronic Chagas' heart disease (cChHD). Their Ab response is suspected to be involved in the cardiac pathogenesis. Reactivity of serum Abs from these patients has been extensively studied but little is known about the diversity of the in vivo IgG repertoire. We analyzed 125 variable H chain (VH) genes and compared it to repertoires from healthy individuals, and patients with autoimmune processes and other infections. VH were from plasma cells isolated from heart tissue of three cChHD patients and from a Fab combinatorial library derived from bone marrow of another cChHD patient. The role of the parasite in shaping the Ab repertoire was assessed analyzing VH genes before and after panning against T. cruzi Ag. Among recovered VH genes, a significantly increased representation of VH4 was observed. Plasma cells at the site of cardiac infiltration showed an increased VH1 usage. CDR3 lengths were similar to the ones found in the healthy repertoire and significantly shorter than in other infections. VH derived from anti-T. cruzi Fab and plasma cells showed a higher proportion of hypermutated genes, 46.9% and 43.75%, respectively, vs 30.9% of the cChHD patient repertoire, pointing to the role of parasite Ags in the shaping of the humoral response in Chagas' disease. No histological evidence of germinal center-like structures was observed in heart tissue. In accordance, VH analysis of heart plasmocytes revealed no evidence of clonal B cell expansion, suggesting that they migrated into heart tissue from secondary lymphoid organs.


Assuntos
Anticorpos Antiprotozoários/genética , Cardiomiopatia Chagásica/imunologia , Rearranjo Gênico do Linfócito B/genética , Cadeias Pesadas de Imunoglobulinas/biossíntese , Cadeias Pesadas de Imunoglobulinas/genética , Região Variável de Imunoglobulina/biossíntese , Região Variável de Imunoglobulina/genética , Adulto , Sequência de Aminoácidos , Anticorpos Antiprotozoários/biossíntese , Antígenos de Protozoários/imunologia , Linfócitos B/imunologia , Linfócitos B/parasitologia , Linfócitos B/patologia , Cardiomiopatia Chagásica/parasitologia , Cardiomiopatia Chagásica/patologia , Doença Crônica , Regiões Determinantes de Complementaridade/biossíntese , Regiões Determinantes de Complementaridade/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Hipermutação Somática de Imunoglobulina/genética , Trypanosoma cruzi/imunologia
2.
Analyst ; 134(9): 1905-10, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19684918

RESUMO

A solid contact ion-selective electrode using for the first time multi-walled carbon nanotubes (MWCNT) for the transducer material was developed for detecting perchlorate in water. To demonstrate the excellent ion-to electron transducer ability of the MWCNTs, a 15 microm thick layer of carboxylated MWCNT was deposited between an acrylic membrane selective to perchlorate ions and a glassy carbon rod used as the substrate and electrical conductor. The electrodes showed a Nernstian response of 57 mV decade(-1) (standard deviation of 3 mV decade(-1) over time and different electrodes) across a wide linear range of 10(-6) to 10(-2) M. The limit of detection was 10(-7.4) M of perchlorate. The response time was less than 10 s for activities higher than 10(-6) M and the intermediate-term potential stability shows a small drift of 0.22 mV h(-1) recorded over 5 hours. The electrode displays a selectivity comparable to liquid-contacted ISEs containing the same membrane.

3.
Horiz. med. (Impresa) ; 23(3)jul. 2023.
Artigo em Espanhol | LILACS-Express | LILACS | ID: biblio-1514221

RESUMO

Objetivo: Evaluar la prevalencia y características de los hallazgos cardiológicos "de Novo" (HCDN) en pacientes pos-COVID a partir de una secuencia diagnóstica cardiológica básica; asimismo, describir los resultados obtenidos en estos pacientes con los distintos métodos diagnósticos, detectar variables clínicas asociadas a la aparición de HCDN durante la evaluación y, por último, detectar el valor diagnóstico de distintos datos de la historia clínica (HC). Materiales y métodos: Se evaluó a pacientes >18 años que padecieron la COVID-19, internados o en su domicilio, mediante interrogatorio, examen físico, electrocardiograma (ECG), ecocardiograma (ECO), rutina de laboratorio y biomarcadores cardíacos entre los 30 y 120 días después del alta. Se incluyeron 246 pacientes (edad: 52 ± 13 años; mujeres: 48 %; COVID-19 leve [37 %], moderado [39 %], grave [24 %]). El 24 % de la población no presentaba síntomas en el momento de la evaluación; en los sintomáticos, la disnea fue lo más frecuente (28 %). El interrogatorio fue el método que reveló mayor porcentaje de sospecha (45 %). El examen físico, el ECG, el ECO y los biomarcadores fueron normales en el 60 %, 55 %, 75 % y 96 % de los pacientes, respectivamente. Resultados: Se detectaron HCDN en 62 pacientes (25,2 %): trastornos del ritmo en 42 (17 %) y disfunción ventricular en 20 (8 %). Cinco presentaron enfermedad coronaria; 6, miocarditis, y 2, valvulopatías. Además, se detectó tromboembolismo pulmonar (TEP) pos-COVID en 10 pacientes, de los cuales seis (2,4 %) debieron internarse nuevamente. Asimismo, en un análisis multivariado, las variables predictoras independientes de los HCDN fueron antecedentes de enfermedad pulmonar obstructiva crónica (EPOC), intervalo QTc > 440 ms, leucocitosis y complicación cardiológica intra-COVID (CCIC). La HC mostró baja sensibilidad y valor predictivo positivo para los HCDN. Conclusiones: Aunque los HCDN se observaron en un cuarto de la población, solo fueron relevantes en el 2 %. De acuerdo con estos datos, mediante esta secuencia diagnóstica y en este lapso, el énfasis debería estar puesto en los pacientes con antecedentes de EPOC y/o complicaciones cardiológicas durante la etapa aguda y/o intervalo QTc prolongado. Los síntomas pos-COVID tuvieron un valor limitado para el diagnóstico de arritmias o disfunción ventricular.


Objective: To evaluate the prevalence and characteristics of "de novo" cardiovascular findings (DNCFs) among post-COVID-19 patients based on a basic cardiovascular diagnostic procedure. Moreover, to describe the patients' results obtained by means of different diagnostic methods, to determine the clinical variables associated with DNCFs during the examination and, finally, to find out the diagnostic value of different data from medical records (MRs). Materials and methods: Patients aged > 18 years who had COVID-19 either at the hospital or at home were evaluated by clinical interviews, physical examination, electrocardiogram (EKG), echocardiogram, routine lab tests and cardiac biomarkers between 30 and 120 days after discharge. A total of 246 patients (age: 52 ± 13 years; women: 48 %; mild, moderate and severe COVID-19: 37 %, 39 % and 24 %, respectively) were included in the study. Twenty-four percent of the population were asymptomatic at the time of the evaluation. In those patients who developed symptoms, dyspnea was the most frequent one (28 %). Interviews were the method with the highest index of suspicion (45 %). Physical examination, EKG, echocardiogram and biomarkers showed normal values among 61 %, 60 %, 75 % and 96 % of the patients, respectively. Results: DNCFs were found in 62 patients (25.2 %): heart rhythm disorders in 42 (17 %) and ventricular dysfunction in 20 (8 %). Five patients had coronary artery disease, six had myocarditis and two had valvular heart disease. In addition, post-COVID-19 pulmonary embolism (PE) was detected in 10 patients, six of whom (2.4 %) had to be rehospitalized. Furthermore, in a multivariate analysis, the independent predictive variables of DNCFs were prior history of chronic obstructive pulmonary disease (COPD), QTc > 440 msec, leukocytosis and intra-COVID-19 cardiovascular complication. MRs showed both low sensitivity and positive predictive value for DNCFs. Conclusions: Although DNCFs were observed in 25 % of the population, only 2 % were significant. According to the data collected from this diagnostic procedure and in this time frame, special attention should be paid to patients with prior history of COPD and/or cardiovascular complications during the acute stage and/or prolonged QTc interval. Post-COVID-19 symptoms were of limited value for the diagnosis of arrhythmias or ventricular dysfunction.

5.
Rev Esp Cardiol ; 58(9): 1054-61, 2005 Sep.
Artigo em Espanhol | MEDLINE | ID: mdl-16185618

RESUMO

INTRODUCTION AND OBJECTIVES: The use of balloon angioplasty to treat native aortic coarctation in pediatric patients is controversial. Our aims were to report our experience with this technique and to compare retrospectively the immediate and medium-term results obtained during 2 distinct time periods. SUBJECTS AND METHOD: 53 patients who underwent balloon angioplasty for native coarctation were divided into 2 groups: (A) those treated between 1985-1988 (n=26); and (B) those treated between 1993-2003 (n=27). Follow-up data were available for all patients. RESULTS: The immediate result was good (i.e., pressure gradient, <20 mmHg) in 18/26 patients in group A (69.2%) and 22/27 (81.5%) in group B. On follow-up, the recoarctation rate was similar in both groups: 33% in group A and 25.6% in group B. Group A patients with recoarctation were referred for surgery, whereas group B patients underwent a second angioplasty (either balloon or stent). At the end of follow-up, angioplasty had been successful in 62% (16/26) of patients in group A vs 85% (23/27) in group B. The incidence of serious complications was lower in group B (4%) than group A (19.2%), as was the incidence of aneurysm: 4% in group B vs 15% in group A. CONCLUSIONS: Balloon angioplasty is an effective alternative to surgery for the treatment of native, localized aortic coarctation. Better selection of suitable patients, use of low-profile catheters, and improved patient care can reduce the incidence of complications. Repeat angioplasty (either balloon or stent) in cases of recoarctation has improved results with this technique.


Assuntos
Angioplastia com Balão , Coartação Aórtica/terapia , Adolescente , Coartação Aórtica/cirurgia , Criança , Pré-Escolar , Interpretação Estatística de Dados , Seguimentos , Humanos , Lactente , Seleção de Pacientes , Recidiva , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento
6.
Rev. colomb. cardiol ; 27(4): 351-352, jul.-ago. 2020. graf
Artigo em Inglês | LILACS, COLNAL | ID: biblio-1289237

RESUMO

Extensive anatomic variability of the coronary arteries in hearts with transposition of great arteries has been described. Usual coronary pattern is defined as right coronary artery arising from posterior facing sinus and left coronary artery from anterior facing sinus. Results of prior case series have suggested that certain coronary patterns are associated with adverse outcomes in surgery (arterial switch operation). We present the case of a neonate with prenatal diagnosis of transposition of great arteries. Postnatal transthoracic echocardiography showed great arteries in a side-by-side relationship (fig. 1). Coronary pattern was described as inverted or with double coronary looping, which represents less than 3% of the anatomical variants. The entire left coronary artery system arose from the posterior-facing sinus, whereas the right coronary artery arose from the aorta anteriorly. Left coronary artery pursued a retropulmonary course, dividing posteriorly into the circumflex and anterior descending arteries (fig. 2). The patient underwent arterial switch operation uneventfully.


Assuntos
Humanos , Vasos Coronários , Transposição das Grandes Artérias Corrigida Congenitamente , Diagnóstico Pré-Natal , Ecocardiografia , Coração
7.
Rev Esp Cardiol ; 55(10): 1057-62, 2002 Oct.
Artigo em Espanhol | MEDLINE | ID: mdl-12383391

RESUMO

INTRODUCTION AND OBJECTIVES: Transcatheter closure of patent ductus arteriosus is a well-established procedure. The aim of this study was to assess the initial and mid-term results of the treatment of PDA with the Amplatzer duct occluder. PATIENTS AND METHODS: From October 1999 to December 2001, 30 children underwent transcatheter closure of persistent ductus arteriosus at a mean SD age of 5 4.02 years (range: 3 months to 14 years) and weight of 20.3 10.3 kg (range: 4.5-45 kg). Infants under 10 kg weight made up 46% of total patients. A lateral view aortogram was made to determine the morphology of the ductus and select the size of the device. Occlusion was achieved using the anterograde venous approach. Follow-up evaluations were made with chest X-ray and echocardiogram at 24 hours and 1, 4 and 12 months after implantation. RESULTS: Twenty-eight patients (93.3%) immediately achieved complete occlusion, and on color Doppler examination the closure rate was 100% within 24 hours of implantation. There was no device embolization. In the follow-up, a 19-month-old patient developed a 20 mmHg gradient across the aortic arch. CONCLUSIONS: Patent ductus arteriosus can be easily occluded with the Amplatz Duct Occluder, which is effective and particularly useful in infants and children with relatively large PDA. Further experience and long-term follow-up are still needed to assess the safety of this device in smaller children.


Assuntos
Permeabilidade do Canal Arterial/terapia , Próteses e Implantes , Adolescente , Fatores Etários , Aortografia , Criança , Pré-Escolar , Permeabilidade do Canal Arterial/diagnóstico por imagem , Seguimentos , Humanos , Lactente , Desenho de Prótese , Radiografia Torácica , Fatores de Tempo , Ultrassonografia Doppler
8.
Food Chem ; 153: 200-6, 2014 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-24491721

RESUMO

The evolution of total capsaicinoids and the individual contents of the five major capsaicinoids: nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin present in the Cayenne pepper (Capsicum annuum L.), during fruit ripening, has been established. Capsaicinoids begin to accumulate gradually in the peppers from the beginning of its development up to a maximum concentration (1,789 µmol/Kg FW). From this time there is initially a sharp decrease in the total capsaicinoid content (32%), followed by a gradual decrease until day 80 of ripening. The two major capsaicinoids present in the Cayenne pepper are capsaicin and dihydrocapsaicin, which represent between 79% and 90%, respectively, of total capsaicinoids depending on fruit ripening. The relative content of capsaicin differs from the evolution of the other four capsaicinoids studied.


Assuntos
Capsaicina/análise , Capsicum/química , Frutas/crescimento & desenvolvimento , Extratos Vegetais/química , Verduras/química , Capsicum/crescimento & desenvolvimento , Cromatografia Líquida de Alta Pressão , Frutas/química , Estrutura Molecular
9.
Dalton Trans ; 41(23): 6980-91, 2012 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-22535338

RESUMO

Palladium complexes bearing monodentate and bidentate phosphine ligands (1-7) were synthesised and used as catalyst precursors in the methoxycarbonylation of norbornene. The catalytic systems bearing ligands 1, 3 and 4 afforded excellent conversions (>99%) and selectivity of the ester (>99%). NMR investigations showed that using complex 1a as the precursor resulted in the protonated phosphine, 1-H(+), being formed under catalytic conditions and thus the addition of acid is not required for the activation of this system since the reaction involving the precursor with methanol under CO pressure produces 2 equivalents of HCl and leads to the formation of the active species. The protonation of ligand 4 under methoxycarbonylation conditions was also observed and the diprotonated diphosphine was isolated and characterised. This compound was tested as a ligand and acid source in a catalysis and provided excellent conversion and high selectivity to the ester.


Assuntos
Monóxido de Carbono/química , Espectroscopia de Ressonância Magnética/métodos , Norbornanos/química , Paládio/química , Pressão , Temperatura , Catálise , Especificidade por Substrato
10.
BMJ Case Rep ; 20112011 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-22674592

RESUMO

Dipylidium caninum is a cestode that requires from the participation of an arthropod in its life cycle. This parasitosis occurs in dogs and cats, and occasionally in human beings. Human cases of D caninum infection have been reported in Europe, Philippines, China, Japan, Latin America and the United States; mostly children, one third of them being infants under 6 months old. The diagnosis of this disease is done by the parasitological study of the feces, observing the characteristics of the gravid proglottids. The treatment is performed by administering broad-spectrum anthelmintics. The authors report a case of a rare infection in a Mexican child.


Assuntos
Infecções por Cestoides/diagnóstico , Infecções por Cestoides/parasitologia , Animais , Anticestoides/uso terapêutico , Cestoides , Fezes/parasitologia , Feminino , Humanos , Lactente , Praziquantel/uso terapêutico
11.
Int J Cardiol Heart Vasc ; 8: 138-146, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28785693

RESUMO

INTRODUCTION AND OBJECTIVES: Different percutaneous interventional procedures are needed to reach and maintain adequate anatomical and physiological conditions for the Fontan circulation. We aim to describe the experience gained at a children's hospital in such interventions, and to analyze the clinical outcomes. METHODS: Retrospective study of all patients with Fontan circulation completed between 1995 and 2013. We analyzed the clinical characteristics and the different types of percutaneous interventions performed, considering three different periods of time: before Glenn surgery, between Glenn and Fontan surgeries, and after Fontan was completed. Survival and time to indication of percutaneous interventions in each period were analyzed, as well as the clinical situation at last follow-up. RESULTS: Of the 91 patients analyzed, 46 (50.5%) required percutaneous interventions. The most frequent procedures were pulmonary artery angioplasty and angioplasty of the Fontan conduit. Estimated survival at 10, 20 and 30 years of age was 96.2%, 94.7% and 89.4%, respectively. There were no significant differences in survival of patients undergoing percutaneous interventions or not. Overall survival and time to indication of percutaneous interventions were significantly lower in the group of patients with right morphology systemic ventricle. Patients with fenestrated Fontan required interventions more frequently. At the end of follow-up, 66 patients (72.5%) were asymptomatic, without significant differences between patients who underwent or did not undergo percutaneous interventions. CONCLUSIONS: Interventional catheterization procedures are often necessary to reach and maintain the fragile Fontan circulation, mainly in patients with right morphology systemic ventricles and fenestrated Fontan conduits.

12.
Dalton Trans ; (7): 853-60, 2008 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-18259615

RESUMO

The asymmetric alkoxycarbonylation of vinylarenes catalysed by palladium complexes bearing chiral phosphine ligands has attracted much attention over the last decades. The products of both mono- and bis(alkoxycarbonylation) reactions are important intermediates in the syntheses of pharmaceuticals such as 2-arylpropionic acids, the most important class of non-steroidal anti-inflammatory drugs. In this article, a general overview of the topics will be presented and the recent advances in this field will be particularly detailed. Besides the term alkoxycarbonylation, hydroesterification and hydroalkoxycarbonylation are also used in the literature to describe this reaction. Furthermore, more specific terms such as methoxycarbonylation can be found. In this report, the term alkoxycarbonylation will be used as the general term, and specific terms will be used to unambiguously define which reaction is meant.

13.
Dalton Trans ; (20): 2741-50, 2008 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-18688406

RESUMO

The diphosphine 3,5-dideoxy-1,2-O-isopropylidene-3,5-bis(di(2-methoxyphenyl)phosphanyl)-alpha-D-xylofuranose (o-MeO-xylophos), which differs from the known 3,5-dideoxy-1,2-O-isopropylidene-3,5-bis(diphenylphosphanyl)-alpha-D-xylofuranose (xylophos) by the presence of 2-methoxy substituents on the P-aryl rings, has been synthesized and characterized. These two ligands have been employed to stabilize the Pd(II) complexes [PdCl2(o-MeO-xylophos)] (1a), [PdCl2(xylophos)] (2a), [PdClMe(o-MeO-xylophos)] (1b), [PdClMe(xylophos)] (2b), [Pd(OTs)(H2O)(o-MeO-xylophos)](OTs) (1c) and [Pd(OTs)(H2O)(xylophos)](OTs) (2c). All complexes have been characterized by multinuclear-NMR spectroscopy. The solid-state structure of 1a has been determined by a single crystal X-ray analysis. The Pd-aqua complexes 1c and 2c have been employed to catalyse the CO-ethene and CO-propene copolymerization as well as the CO-ethene-propene terpolymerization reaction in MeOH. The catalytic activity and the molecular weight of the polyketones have been compared to those of the products obtained with analogous catalysts, [Pd(H2O)2(o-MeO-dppp)](OTs)2 (3c) and [Pd(H2O)(OTs)(dppp)](OTs) (4c), bearing the classical 1,3-bis(diphenylphoshino)propane ligand (dppp). Under comparable catalytic conditions, all catalysts produce structurally similar polymeric materials, with 1c yielding the largest propene incorporation as well as the highest productivity of low-molecular-weight terpolymers.

14.
Dalton Trans ; (27): 2859-61, 2007 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-17607399

RESUMO

Two novel bis(o-methoxyphenyl) phosphinoalkylsulfonate (P-O) ligands have been prepared through a new and sustainable synthetic route; they are air stable as well as water soluble and have been applied in Pd-catalysed Suzuki-Miyaura cross-coupling reactions in neat water in conjunction with microwave heating.

15.
Dalton Trans ; (47): 5524-30, 2007 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-18043812

RESUMO

Palladium complexes bearing phospholane 1 and phosphetane 2-4 ligands have been synthesised to be used as catalyst precursors in the asymmetric methoxycarbonylation of vinyl arenes. Single crystals of the complex [PdCl2(2)2] II were obtained from a toluene solution and analysed by X-ray crystallography. Using these complexes, excellent regioselectivity (up to 99%) to the branched esters was obtained. Phosphetane ligands provide higher enantioselectivity than the phospholane under the same reaction conditions and an important influence of the substrate was observed. Enantioselectivity up to 50% was obtained using 4-methoxystyrene.


Assuntos
Hidrocarbonetos Aromáticos/química , Paládio/química , Compostos de Fósforo/química , Catálise , Cristalografia por Raios X , Ligantes , Modelos Moleculares , Estrutura Molecular , Estereoisomerismo
16.
Dalton Trans ; (47): 5590-602, 2007 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-18043822

RESUMO

In this paper we report on a comparative study of the non-alternating CO-C(2)H(4) copolymerization catalyzed by neutral Pd(II) complexes with the phosphine-sulfonate ligands bis(o-methoxyphenyl)phosphinophenylenesulfonate and bis(o-methoxyphenyl)phosphino-ethylenesulfonate. The former ligand, featuring a lower skeletal flexibility, has been found to form more active catalysts as well as produce polyketones with higher molecular weight and higher extra-ethylene incorporation. Operando high-pressure NMR studies have allowed us to intercept, for the first time, Pd(II)(phosphine-sulfonate) beta-chelates in the non-alternating copolymerization cycle, while model organometallic reactions have contributed to demonstrate that Pd(II) (phosphine-sulfonate) fragments do not form stable carbonyl complexes. The opening of the beta-chelates has been found to be a viable process by either comonomer, which contrasts with the behaviour of Pd(II) (chelating diphosphine) catalysts for the perfectly alternating copolymerization.

17.
Dalton Trans ; (15): 2557-62, 2005 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-16025175

RESUMO

Thioether-phosphinite ligands (P-SR, R = Ph, Pr(I) and Me) bearing substituents with different steric demands on the sulfur centre were tested in the rhodium- and iridium-catalysed asymmetric hydrogenation of prochiral olefins. High enantiomeric excesses (up to 96%) and good activities (TOF up to 860 mol product x (mol catalyst precursor x h)(-1)) were obtained for alpha-acylaminoacrylates derivatives. Our results show that enantiomeric excesses depended strongly on the steric properties of the substituent in the thioether moiety, the metal source and the substrate structure. A bulky group in the thioether moiety along with the metal Rh had a positive effect on enantioselectivity. Reaction of these chiral ligands with [M(cod)2]BF4(M = Ir, Rh; cod = 1,5-cyclooctadiene) yielded complexes [M(cod)(P-SR)]BF4, which were present in only one diastereomeric form having the sulfur substituent in a pseudoaxial disposition. The addition of H2 to iridium complexes gave the cis-dihydridoiridium(iii) complexes [IrH2(cod)(P-SR)]BF4. For complexes [IrH2(cod)(P-SPh)]BF4 and [IrH2(cod)(P-SMe)] only one isomer was present in solution. However, for the complex [IrH2(cod)(P-Si-Pr)]BF4, which contained the more hindered substituent on sulfur, two isomers were detected. In all cases there was a pseudoaxial disposition of the sulfur substituents.


Assuntos
Alcenos/síntese química , Irídio/química , Compostos Organometálicos/química , Ácidos Fosfínicos/química , Ródio/química , Sulfetos/química , Alcenos/química , Catálise , Hidrogenação , Conformação Molecular , Compostos Organometálicos/síntese química , Estereoisomerismo
18.
J Org Chem ; 67(11): 3796-801, 2002 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-12027696

RESUMO

A series of novel diphosphite ligands derived from readily available D-(+)-glucose have been synthesized. These ligands were screened in the Rh-catalyzed hydrogenation of a series of alpha,beta-unsaturated carboxylic acid derivatives. Both excellent enantioselectivities (ee up to >99%) and activities were achieved. The advantage of these ligands is that their modular nature allows an easy systematic variation in the configuration of the stereocenters (C-3, C-5) at the ligand backbone and in the biaryl substituents, so the optimum configuration for maximum enantioselectivity in asymmetric hydrogenation can be determined. Results show that enantiomeric excesses depend strongly on the absolute configuration of C-3 and slightly on the stereocenter carbon C-5, while the sense of the enantiodiscrimination is predominantly controlled by the configuration of the biaryls at the phosphite moieties. Moreover, the presence of bulky substituents at the ortho-positions of the biaryl diphosphite moieties has a positive effect on enantioselectivity.


Assuntos
Glucose/análogos & derivados , Fosfitos/síntese química , Catálise , Hidrogenação , Ligantes , Fosfitos/química , Estereoisomerismo
19.
Chemistry ; 10(15): 3747-60, 2004 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-15281159

RESUMO

Continuing our studies into the effect that N-N' ligands have on CO/styrene copolymerization, we prepared new C(1)-symmetrical pyridine-imidazoline ligands with 4',5'-cis stereochemistry in the imidazoline ring (5) and 4',5'-trans stereochemistry (6-10) and compared them with our previously reported ligands (1-4). Their coordination to neutral methylpalladium(II) (5 a-10 a) and cationic complexes (5 b-10 b), investigated in solution by NMR spectroscopy, indicates that both the electronic and steric properties of the imidazolines determine the stereochemistry of the palladium complexes. The crystal structures of two neutral palladium precursors [Pd(Me)(2-n)Cl(n)(N-N')] (n=1 for 8 a; n=2 for 9 a') show that the Pd-N coordination distances and the geometrical distortions in the imidazoline ring depend on the electronic nature of the substituents in the imidazoline fragment. Density functional calculations performed on selected neutral and cationic palladium complexes compare well with NMR and X-ray data. The calculations also account for the formation of only one or two stereoisomers of the cationic complexes. The performance of the cationic complexes as catalyst precursors in CO/4-tert-butylstyrene copolymerization under mild pressures and temperatures was analyzed in terms of the productivity and degree of stereoregularity of the polyketones obtained. Insertion of CO into the Pd-Me bond, which was monitored by multinuclear NMR spectroscopy, shows that the N ligand influences the stereochemistry of the acyl species formed.

20.
Medicina (Guayaquil) ; 11(2): 126-130, jun. 2006.
Artigo em Espanhol | LILACS | ID: lil-652661

RESUMO

Tipo de estudio: retrospectivo, descriptivo, longitudinal y analítico. Objetivo: Determinar las manifestaciones clínicas y métodos diagnósticos de la CIV, eficaces y económicos en niños atendidos en el hospital “Roberto Gilbert“. Metodología: se incluyeron en este estudio 150 pacientes con CIV como defecto único que acudieron a la consulta externa y con edades comprendidas entre 0 - 5 años. Resultados: el grupo de edad en que se diagnosticó la mayoría de los casos fue 0-1 años, 52,6% hombres y 47,4% mujeres. Las manifestaciones clínicas predominantes fueron: soplo cardiaco 100%, taquipnea 66,6% y disnea 50%. El método diagnóstico mas eficaz y efectivo fue el Eco-Doppler, permitiendo conocer el diámetro del defecto: < 0,5 cm (43,3%), 0,5 -1,5 cm (53,3%) y > 1,5 cm (3,3%); la localización: CIV muscular (35,3%) y CIV perimembranosa (64,6%) y el mecanismo de semicierre: restrictiva (espontáneo) 71,3% y corrección quirúrgica 28,6%. Conclusiones: en este grupo de estudio se encontró como principal manifestación clínica de la CIV, soplo cardiaco localizado en el borde esternal inferior izquierdo de intensidad V/VI, y el diagnóstico de certeza se lo obtuvo mediante la combinación de auscultación, radiografía de tórax, EKG y Eco Doppler.


Type of study: retrospective, descriptive, longitudinal and analytic. Objective: to determine clinic manifestation and diagnostic manifestations of CIV, effective and economic in children of the Dr. “Roberto Gilbert” hospital. Methodology: there were included in this study 150 patients with CIV like unique defect that coming at the external consulting and ages between 0 – 5 years old. Results: the age group which was diagnosed the most of cases was 0 – 1 years, 52,6% men and 47,4% women. The clinic manifestations predominant was: cardiac murmur 100%, taquipnea 66,6% and disnea 50%. The diagnostic method more effective and efficient was the Eco-Doppler, allowing to know the diameter of the defect: < 0,5 cm (43,3%), 0,5-1,5 cm (53,3%) y CIV perimembranosa (64,6%) and the semicloses mechanism: restrictive (spontaneous) 71,3% and surgical correction 28,6%. Conclusions: in this group, it found like principal clinic manifestations of CIV, cardiac murmur located in the right lower costal margin, of intensity V/VI, and the right diagnostic is combination of auscultation, X-ray of thorax, EKG and Eco Doppler


Assuntos
Masculino , Feminino , Recém-Nascido , Lactente , Pré-Escolar , Anormalidades Congênitas , Cardiopatias Congênitas , Comunicação Interventricular , Cianose , Insuficiência de Crescimento , Sopros Sistólicos , Septo Interventricular
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA