A DFT periodic study on the interaction between O2 and cation exchanged chabazite MCHA (M = H+, Na+ or Cu+): effects in the triplet-singlet energy gap.

O(2) adsorption in proton, sodium and copper exchanged chabazite has been studied using periodic and cluster approaches by means of density functional theory. The Grimme's correction has been used to include the dispersion contribution to B3LYP. Two cation locations have been considered: one with the cation at the six-membered ring (MCHA(I)) and the other with the cation at the 8-membered ring (MCHA(IV)). The O(2)-HCHA and O(2)-NaCHA adsorption complexes present a eta(1)-O(2) bent coordination. The adsorption energies, which are due to dispersion, are between -15 and -19 kJ mol(-1), in agreement with the experimental values. On the other hand, the O(2) coordination to CuCHA is through a eta(2)-side-on mode with a square planar coordination around the metal center. This structure favors the Cu d -->pi* O(2) charge transfer which becomes the predominant stabilizing factor. The adsorption of singlet states of O(2) in HCHA and NaCHA, modeled with an ONIOM M12T:48T, is of the same nature as that of the ground state, and only the highest in energy (1)Sigma is significantly more stabilized in MCHA than the triplet state by 14 to 24 kJ mol(-1). The adsorption of singlet O(2) in Cu exchanged zeolites presents a higher electron transfer from Cu(+) to O(2) than that calculated for the triplet species and thus both singlet states are stabilized with respect to the ground state O(2). Generally, singlet oxygen appears more attractive to active zeolite models than those calculated with triplet oxygen, indicating a source of oxidative efficiency for designed structures.

Theoretical study of imidazole...NO complexes.

A set of weak complexes between imidazole (Imi) and nitric oxide (NO) were calculated with UMP2/6-31++G(d,p) and UMP2/6-311++G(2d,2p) levels of theory. Planar and nonplanar geometries were considered. Complexes of NO and protonated imidazole (ImiH(+)) were also studied due to the biological important effect of Imi protonation. It was found that ring protonation increases the stability of planar complexes and does not affect significantly nonplanar complexes. The Z-H...XY (Z = C, N and X, Y = N, O) interactions resulted as hydrogen bonds according to Koch and Popelier criteria based on AIM theory. Charge transfer was also found very important for complex stabilization within our theoretical framework. Planar NO...ImiH(+) complexes are more stable than those obtained with neutral Imi.

The Assisi Think Tank Meeting Survey of post-mastectomy radiation therapy in ductal carcinoma in situ: Suggestions for routine practice.

BACKGROUND: Risk factors for local recurrence after mastectomy in ductal carcinoma in situ (DCIS) emerged as a grey area during the second "Assisi Think Tank Meeting" (ATTM) on Breast Cancer. AIM: To review practice patterns of post-mastectomy radiation therapy (PMRT) in DCIS, identify risk factors for recurrence and select suitable candidates for PMRT. METHODS: A questionnaire concerning DCIS management, focusing on PMRT, was distributed online via SurveyMonkey. RESULTS: 142 responses were received from 15 countries. The majority worked in academic institutions, had 5-20 years work-experience and irradiated <5 DCIS patients/year. PMRT was more given if: surgical margins <1 mm, high-grade, multicentricity, young age, tumour size >5 cm, skin- or nipple- sparing mastectomy. Moderate hypofractionation was the most common schedule, except after immediate breast reconstruction (57% conventional fractionation). CONCLUSIONS: The present survey highlighted risk factors for PMRT administration, which should be further evaluated.

Radiation therapy for the treatment of benign vascular, skeletal and soft tissue diseases.

The concept of radiation therapy for the treatment of benign diseases refers to the use of moderate to high-energy ionising radiation as part of the treatment of non-malignant, but not necessarily harmless, diseases. The usefulness of radiation therapy, based on the anti-inflammatory properties of ionising radiation, has long been known. Apart from the treatment of intracranial benign tumours, such as meningiomas and neurinomas, the prevention of cardiovascular restenosis or treatment of skeletal degenerative diseases are, without doubt, the main fields of action for radiation therapy in benign conditions. Nonetheless, many other non-cancer entities may benefit from ionising radiation therapy treatment. The purpose of this review is to highlight and update indications for treatment with radiation therapy in benign conditions, focusing on skeletal degenerative processes, vascular conditions and soft tissue diseases.

Patterns of retinal light absorption related to retinitis pigmentosa mutants from in silico model structures of rhodopsin.

Changes induced by mutations in rhodopsin that are associated with the degenerative visual disease retinitis pigmentosa result in an altered pattern of light absorption according to quantum mechanical simulations and reference experimental works. Eleven single-point mutations associated with retinitis pigmentosa at and in the proximity to the retinal binding pocket of rhodopsin have been modeled in silico and their spectra calculated with the NDOL (Neglect of Differential Overlap accounting L azimuthal quantum number) a priori method. The altered pattern of absorption found would lead to cumulative consequences in energy dissipation with aging. Different energy balances in the case of mutants at the very molecular level, compared to native nonmutated rhodopsin, can cause permanent cellular stress and would play a role in the progression of the retine degenerative process. It could explain the worsening of the pathological condition mostly in adults and suggests the probable beneficial effects of using quenching drugs and protection devices against excess of light in the early stages of life for avoiding or reducing potential damage.

Molecular orbital model of the influence of interaction between O2 and aluminosilicate sites on the triplet-singlet energy gap and reactivity.

The behavior of O(2) molecule in models of acid aluminosilicate sites on any kind of material was investigated using reliable QM ab initio calculations. The triplet-singlet energy gap of isolated O(2) was calculated at confident levels of theory with different basis sets as a reference. Models of aluminosilicate active sites interacting with oxygen in their singlet and triplet electronic states were considered for two kinds of O(2) arrangements. Geometry optimizations were performed on both non-corrected and corrected BSSE potential energy surfaces, realizing that good modeling of heavy atom-hydrogen interactions is sensitive to BSSE corrections during these processes. Energies were further evaluated at higher level of theory to test tendencies. Singlet oxygen appears more attractive to active aluminosilicate sites than those calculated with triplet oxygen, indicating a source of oxidative efficiency for designed nanostructures containing such molecular residues. It was clearly seen that aluminosilicate groups, appearing ubiquitously in several materials, could reduce the O(2) triplet-singlets energy gap by at least 10 kJ/mol. Some elegant features of oxygen interactions with such sites were further analyzed by means of the atoms in molecules (AIM) theory.

Estado actual de la esclerosis múltiple en Colombia / Current state of multiple sclerosis in Colombia

Introducción: Dos estudios epidemiológicos de esclerosis múltiple (EM) la describen como de bajo riesgo en Colombia. Hay, sin embargo, nuevos sistemas de información que permiten una aproximación más precisa. Objetivo:Estimar la prevalencia nacional de EM, así como por regiones del país, y analizar los costos de los fármacos usados en Colombia. Materiales y métodos: Se obtuvieron datos del Registro Individual de Prestación de Servicios de Salud (RIPS), con el código diagnóstico G35X para esclerosis múltiple, tomando los diagnósticos confirmados nuevos y repetidos entre 2009 y 2013, por sexo, grupo etario y departamento. Para el análisis de medicamentos se usó la base de datos Sismed del 2014, incluyendo los fármacos disponibles en Colombia: interferón beta-1A, interferón beta-1B, acetato de glatiramer, natalizumab, fingolimod y mitoxantrona. Resultados:Según los RIPS, en Colombia se atendieron, en el período 2009-2013, un total de 3.462 personas con diagnóstico de esclerosis múltiple. La prevalencia nacional para el período fue de 7,52/100.000, con las cifras más altas en Bogotá (16,25), donde se atendieron 1.213 pacientes, seguido de los departamentos del Quindío (13,03) y Risaralda (11,18). La mayor proporción de pacientes se encuentra entre los 50 y 54 años de edad, y las mujeres representan más del 70%. Adicionalmente, en 2014 se invirtieron 86.000 millones de pesos (43 millones de dólares) en medicamentos para esclerosis múltiple, lo que equivale a cerca de 25 millones por paciente. Conclusión: Colombia podría ser un país con riesgo intermedio para esclerosis múltiple, una enfermedad que acarrea altos costos para el sistema de salud.

Introduction: Two local epidemiological studies describe Colombia as low risk for multiple sclerosis (MS). New information systems, which allow for a more accurate approximation, are currently available. Objective: To estimate the national prevalence of MS, as well as by regions, and to analyze national drug costs. Materials and methods: We obtained data from the Individual Registry of Health care provision (RIPS), with the diagnosis code G35x for multiple sclerosis, taking the confirmed new and repeated diagnoses between 2009 and 2013, by gender, age group and geographical location. For the analysis of medications, we use the database SISMED 2014 searching for all drugs available in Colombia: interferon beta 1A, interferon beta 1B, glatiramer acetate, natalizumab, mitoxantrone and fingolimod. Results: According to the RIPS, 3,462 patients with diagnosis of MS contacted the health system in Colombia during the period 2009-2013. The national prevalence for the period was 7.52 / 100,000, with the highest figure in Bogota (16.25) with 1213 patients, followed by Quindío (13.03) and Risaralda (11.18). The largest proportion of patients were in the 50 to 54 years age group, and 70% were women. Additionally, in 2014 Colombia spent COP $ 86 billion pesos (43 million US dollars) for MS drugs, around US$12,500 per patient/year. Conclusion: Colombia is a country with intermediate risk for MS, a disease that implies a high direct cost for the health system.

Criptococosis meníngea: características clínicas y de laboratorio / Meningeal criptococcosis: clinical and laboratory characteristics

Introducción. La incidencia de infecciones causada por Cryptococcus neoformans ha aumentado en los últimos 20 años como resultado de la epidemia del virus de inmunodeficiencia humana, y el aumento de las terapias inmunosupresoras. En Colombia se realizó un estudio clínico y epidemiológico de la criptococosis, con una incidencia promedio anual en la población general de 2.4 casos por millón de habitantes; 891 (95.7%) personas con compromiso del sistema nervioso central; el virus de inmunodeficiencia humana se encontró en 78.1% de los casos. Objetivo. Describir las características demográficas, clínicas y paraclínicas en pacientes con primer episodio decriptococosis meníngea. Determinar la frecuencia de cultivos positivos para criptococo en líquido cefalorraquídeoal completar 500 mgs y 1 g de anfotericina B. Materiales y Métodos. Durante dos años se recolectaron 18 pacientes con primer episodio de criptococosis meníngea confirmada con cultivo positivo para criptococo en líquido cefalorraquídeo. Se describen las características demográficas, clínicas, de laboratorio y los cambios post-tratamiento. Resultados. El 77.7% fueron hombres. El 100% de los pacientes consultaron por cefalea. La infección por el virus de inmunodeficiencia humana se encontró en el 83.3%. El citoquímico de liquido cefalorraquídeo al ingreso mostróun promedio de 24.8 leucocitos/ul, proteínas 117mg/dL, y glucosa 32.1 mg/dL. Al completar 1g de anfotericina B, mostró un promedio de 20.2 leucocitos/ul, proteínas 85.7 mg/dL, y glucosa 42.3 mg/dL. La frecuencia de cultivos positivos en líquido cefalorraquídeo a los 500 mgs de anfotericina B fue del 23% y al completar 1 g fue del 0%. La tinta china persistió positiva al finalizar el tratamiento en el 53.8% y el látex para criptococo reactivo en el 84.6%...

Introduction. The incidence of infections caused by Cryptococcus neoformans has increased over the past 20 years as a result of the Human Immunodeficiency Virus epidemic and the raise of immunosuppressive therapies. A clinical and epidemiological study in Colombia found a mean annual incidence rate of cryptococcosis in the...

Computational study of noncovalent complexes between formamide and formic acid.

The geometries and binding energies of 1:1, 1:2, and 1:4 formic acid-formamide complexes (FA-FMA) are calculated by quantum chemical procedures. Vibrational spectra and intermolecular distances of the most stable FA-FMA dimers as well as the influence of the basis set superposition error (BSSE) on the geometries and energies of the dimers are also discussed. All FA-FMA dimers are optimized at the B3LYP/cc-pVTZ, the MP2/cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ levels of theory to study the influence of the level of theory on the calculated geometries and energies. CCSD(T)/cc-pVTZ single-point calculations at the MP2/aug-cc-pVTZ-optimized geometries were performed as reference for estimating the quality of lower level calculations. These calculations allow us to qualitatively describe the competition between different types of hydrogen-bonding interactions in FA-FMA complexes. FA-FMA dimers are compared to other formamide complexes and to the FA-FMA crystal structure.

Furan-formic acid dimers: an ab initio and matrix isolation study.

The dimers formed by formic acid (FA) and furan are investigated by ab initio methods and matrix isolation spectroscopy. Nine complexes with binding energies between -3.91 and -0.82 kcal/mol (MP2/6-311++G(d,p) + ZPE + BSSE) are identified. Another five weaker bound complexes are localized at lower level of theory only. The binding in the furan-FA dimers can be described in terms of OH...O, C=O...H, HO...H, CH...O, OH...pi, and CH...pi interactions. Therefore, the furan-FA complexes are classified in two types: (1) the dimers where the OH hydrogen of formic acid interacts with the furan molecule and (2) the dimers where the main interactions of FA with the furan molecule are via the less acidic CH hydrogen. Duning's and Pople's triple and double basis sets were used to study the dependence of the geometries and energies of the complexes from the basis set. BSSE (basis set superposition error) counterpoise corrections (CP) were included during the geometry optimizations of all dimers at the MP2/6-31G(d,p) level of theory. Matrix isolation spectroscopy allowed us to record the IR spectrum of aggregates between FA and furan. By comparison of the experimental IR spectrum with calculated IR spectra of a variety of complexes, it was possible to identify the most stable furan-FA dimer as the major product of the aggregation.

Noncovalent complexes between dimethyl ether and formic acid--an ab initio and matrix isolation study.

The complexes formed by noncovalent interactions between formic acid and dimethyl ether are investigated by ab initio methods and characterized by matrix isolation spectroscopy. Six complexes with binding energies between -2.26 and -7.97 kcal mol(-1) (MP2/cc-pVTZ+zero point vibrational energy+basis set superposition erros) are identified. The two strongest bound complexes are, within a range of 0.3 kcal mol(-1), isoenergetic. The binding in these six dimers can be described in terms of OH...O, C=O...H, C-O...H and CH...O interactions. Matrix isolation spectroscopy allowed to characterize the two strongest bound complexes by their infrared spectra.

Theoretical model of internal rotation in monosubstituted derivatives of furfural.

The present work explores the effect of substitution in all free positions of furfural on conformational preferences of formyl group by using ab-initio calculations at the MP2/6-31G(p,d) level of theory. Theoretical modeling was made in vacuo. The selected substituents were -CH(3), NH(2), NO(2) and F groups in 3, 4, 5 and ipso carbonyl positions. Geometries of all derivatives were analyzed and it is ascertained that substitution has not important consequences on furan ring geometry. Differences of energy between OO-cis and trans conformers and energy barriers between them are described and extreme cases are explained. Interesting features appear in the cases of -NH(2) and -NO(2) groups, and particularly when the 3 and ipso carbonyl positions are substituted. Variations in energy barriers are correlated with variations in C2-C6 distances for the transition states and planar forms. Substitution effect on Mülliken charges are analyzed and related with internal rotation energy barriers and differences between conformers.