Guidelines for the assembly of hydrogen-bonded macrocycles.

The formation of well-defined, discrete self-assembled architectures relies on the interplay between non-covalent interactions and cooperative phenomena. In particular, chelate or intramolecular cooperativity is responsible for the assembly of closed, cyclic structures in competition with open, linear oligomers, and it can be enhanced in several ways to increase the stability of a given cycle size. In this article, we review the work of several researchers on the synthesis of hydrogen-bonded macrocycles from ditopic molecules and analyze the main factors, often interrelated, that influence the equilibrium between ring and chain species. Emphasis will be set on the diverse features that can increase cyclization fidelity, including monomer geometry, template effects, conformational effects, intramolecular interactions and H-bonding pattern.

Dye-conjugated complementary lipophilic nucleosides as useful probes to study association processes by fluorescence resonance energy transfer.

Modern supramolecular chemistry relies on the combination of diverse analytical techniques that can provide complementary information on complex self-assembly landscapes. Among them, resonance energy transfer, monitored by fluorescence emission spectroscopy, arises as a sensitive and convenient phenomenon to report binding intermolecular interactions. The use of molecular probes labelled with suitable complementary energy-transfer pairs can provide valuable information about the thermodynamics, kinetics and self-sorting characteristics of a particular self-assembled system. The objective of this work is to generate a set of nucleoside FRET probes that can be reliably employed to prove and analyse quantitatively H-bonding interactions between complementary Watson-Crick pairs. We first describe the preparation of a set of lipophilic nucleosides that are linked to a π-conjugated functional fragment. The bases include guanosine and 2-aminoadenosine as purine heterocycles, and cytidine and uridine as complementary pyrimidine bases. The π-conjugated moiety comprises either a short phenylene-ethynylene oligomer, a bithiophene, or a BODIPY dye. We then demonstrate that the last two chromophores constitute an energy donor-acceptor couple and that donor emission quenching can be related to the ratio of molecules bound to the complementary acceptor pair. Hence, fluorescence spectroscopy in combination with resonance energy transfer, is shown here to be a useful tool to study and quantify the association and self-sorting events between complementary and non-complementary nucleosides in apolar aromatic solvents, where the binding strength is considerably high, and sensitive techniques that employ low concentrations are demanded.

Circulating miR-323-3p is a biomarker for cardiomyopathy and an indicator of phenotypic variability in Friedreich's ataxia patients.

MicroRNAs (miRNAs) are noncoding RNAs that contribute to gene expression modulation by regulating important cellular pathways. In this study, we used small RNA sequencing to identify a series of circulating miRNAs in blood samples taken from Friedreich's ataxia patients. We were thus able to develop a miRNA biomarker signature to differentiate Friedreich's ataxia (FRDA) patients from healthy people. Most research on FDRA has focused on understanding the role of frataxin in the mitochondria, and a whole molecular view of pathological pathways underlying FRDA therefore remains to be elucidated. We found seven differentially expressed miRNAs, and we propose that these miRNAs represent key mechanisms in the modulation of several signalling pathways that regulate the physiopathology of FRDA. If this is the case, miRNAs can be used to characterize phenotypic variation in FRDA and stratify patients' risk of cardiomyopathy. In this study, we identify miR-323-3p as a candidate marker for phenotypic differentiation in FRDA patients suffering from cardiomyopathy. We propose the use of dynamic miRNAs as biomarkers for phenotypic characterization and prognosis of FRDA.

El transfer de UCIP a planta / No disponible

No disponible

Synthesis and electronic properties of nitrogen-bridged dimers of boron subphthalocyanines.

The synthesis of new symmetric and unsymmetric axial nitrogen-bridged dimers of subphthalocyanines (µ-azo dimers) has been carried out via activated triflate intermediates. Their spectroscopic and electrochemical properties have been studied and compared to their µ-oxo analogues.

Synthesis and complementary self-association of novel lipophilic π-conjugated nucleoside oligomers.

A series of lipophilic nucleosides comprising natural and non-natural bases that are π-conjugated to a short oligophenylene-ethynylene fragment has been synthesized. These bases comprise guanosine, isoguanosine, and 2-aminoadenosine as purine heterocycles, and cytidine, isocytosine and uridine as complementary pyrimidine bases. The hydrogen-bonding dimerization and association processes between complementary bases were also studied by (1)H NMR and absorption spectroscopy in order to obtain the relevant association constants.

Branched and bulky substituted ruthenium sensitizers for dye-sensitized solar cells.

We report on the synthesis, and photovoltaic performances of four novel Ru(ii)-bipyridine heteroleptic complexes TT206-209, incorporating branched and bulkier alkyl chains compared to their linear analogues C106 and CYC-B11 previously reported. In both series, we found that dyes containing 2-methyl-hex-2-yl substitution gave better performances than 1,1-dipropylbutyl. The best overall performance over the four dyes was obtained for TT207 (CYC-B11 analogue), which contains 2-methylhex-2-yl type substitution, achieving an overall PCE of 8.5%. Furthermore, the optimization of TT207/DSSCs, with respect to the dye-uptake solvent and electrolyte composition, led to a maximum PCE of 9.1% under AM1.5 G standard conditions.

Molecular structure of chloro-dodecafluorosubphthalocyanato boron(III) by gas-phase electron diffraction and quantum chemical calculations.

The molecular structure of the chloro-dodecafluorosubphthalocyaninato boron(III) (F-SubPc) was determined with use of Gas Electron Diffraction (GED) and high-level quantum chemical calculations. The present results show that the F-SubPc molecule has a cone-shaped configuration, isoindole units are not planar, and the pyrrole ring has an envelope conformation. The structure parameters in the gas phase are determined. Some structural details can be observed such as the dihedral angle about the bond connecting the pyrrole ring and the benzene ring being ca. 174 degrees . High-level theoretical calculations with several extended basis sets for this molecule have been carried out. The calculations are in very good agreement with experimental methods: X-ray and GED. Nevertheless, some disagreements particularly related to the B-Cl bond distance found in GED are discussed. Vibrational frequencies were computed obtaining eight values below 100 cm-1 and three bending potentials were examined. They suggest that this molecule is very flexible.

Evolución clínica de niños asmáticos graves incorporados al área terapéutica de natación / Clinical course of the effect of inhaled nitric oxide during the first week of treatment

Se realizó un estudio prospectivo en un grupo de 75 niños asmáticos graves, incorporados al área terapéutica de natación, ubicada en la piscina 'Mártires de Barbados', en el período comprendido entre septiembre de 1997 y junio de 1999, con el objetivo de determinar el estado evolutivo de los mismos. A estos pacientes se les realizó una terapéutica natural, dirigida por un equipo multidisciplinario y basada fundamentalmente en las medidas educativas acerca de la enfermedad, la práctica de ejercicios respiratorios y la natación. El 80 por ciento de los pacientes se encontraban en edades comprendidas entre seis y nueve años. Al inicio del tratamiento el 100 por ciento de los pacientes presentaban 10 o más crisis al año. Y a los dos años en el área, ascendió a un 96 por ciento el número de pacientes que presentó una evolución satisfactoria con marcada reducción del número de ingresos. También al cabo de los dos años de tratamiento logran disminuir las dosis de fármacos el 57,3 por ciento de los pacientes, mientras que el 38,7 por ciento del total permanecían con terapéuticas farmacológicas. Consideramos que un tratamiento donde se combinen las medidas preventivas, los ejercicios respiratorios y la práctica de la natación es fundamental en el manejo integral del niño asmático severo (AU)

Evolución clínica de niños asmáticos graves incorporados al área terapéutica de natación

Se realizó un estudio prospectivo en un grupo de 75 niños asmáticos graves, incorporados al área terapéutica de natación, ubicada en la piscina "Martires de Barbados", en el período comprendido entre septiembre de 1997 y junio de 1999, con el objetivo de determinar el estado evolutivo de los mismos. A estos pacientes se les realizó una terapéutica natural, dirigida por un equipo multidisciplinario y basadas fundamentalmente en las medidas educativas scerca de la enfermedad, la prácticas de ejercicios respiratorios y la natación. El 80 por ciento de los pacientes se encontraban en edades comprendidas entre seis y nueve años. Al inicio del tratamiento el 100 por ciento de los pacientes presentaban 10 o0 más crisis al año. Y a los dos años en el área, ascendió a un 96 por ciento el número de pacientes que presentó una evolución satisfactoria con marcada reducción del número de ingreso. También al cabo de los años de tratamiento logran disminuir las dosis de fármacos el 57,3 por ciento de los pacientes, mientras que el 38,7 por ciento del total permanecían con terapéuticas farmacológicas. Consideramos que un tratamiento donde se combinen las medidas preventivas, los ejercicios respiratorios y la práctica de natación es fundamental en el manejo integral del niño asmático severo

[Reintervention to complete the surgical treatment of thyroid cancer. Indications and histopathological findings]. / Reintervención para completar el tratamiento quirúrgico en cáncer de tiroides. Indicaciones y hallazgos histopatológicos.

In Mexico, 39% of 158 patients operated on for thyroid cancer require reoperative thyroid surgery. We retrospectively reviewed the indications and histopathological findings of 60 patients reoperated on because of: a) suspected persistent or recurrent disease; b) high risk patients treated by lobectomy; c) different histology; d) complete lack of information, e) and distant metastasis. In 53 cases (88%), the initial surgery was nodulectomy or lobectomy, and in seven (11%) was subtotal or near-total thyroidectomy. Among the 60 reoperations, 50 were completion total thyroidectomy and 10 were near-total thyroidectomy. In 27 cases (45%) a neck dissection was additionally done. Histologic examination revealed thyroid carcinoma in 32 cases (53%) and neck node metastasis in 28 cases (47%). Complications included six cases (9%) of permanent palsy of the recurrent laryngeal nerve after the initial surgery outside of our hospital and two cases (1.75%) of reoperated cases. In four reoperated patients (6.6%), permanent hypoparathyroidism was developed. It is mandatory to complete thyroidectomy and neck dissection in a high proportion of patients initially treated in general hospitals due to an inadequate criteria in the selection of the extension of thyroidectomy and treatment of neck node metastases. Histologic findings of these patients support our indications to complete the surgical treatment.

El electrocardiograma y la radiografía de tórax en el diagnóstico causal de la insuficiencia cardíaca congestiva

El estudio cardiográfico es la mejor forma de determinar la causa de la insuficiencia cardíaca congestiva (ICC), pero por diferentes razones no se realiza sistemáticamente. El presente trabajo evaluó la sensibilidad y la especificidad de la radiografía de tórax (RT) y el electrocardiograma (ECG) para determinar su valor diagnóstico, como exámenes alternativos. Se estudiaron 65 fallecidos, con necropsias realizadas en los cuales la causa básica de muerte fue la ICC. Aunque la especificidad y el valor predictivo del ECG fueron del 100 porciento para la cardiopatía isquémica su sensibiliad (20.83 porciento) no aconseja su uso para descartar la presencia de esta enfermedad. en el caso de la hipertrofia cardíaca, este examen no produjo una modificación importante de la probabilidad previa de que esta estuviera presente por lo que su utilidad en este sentido es poca. En cuanto a la RT, aunque con limitaciones, puede ser útil para descartar la existencia de cardiomegalia (AU)