Atmospheric Spectroscopy and Photochemistry at Environmental Water Interfaces.

The air-water interface is ubiquitous in nature, as manifested in the form of the surfaces of oceans, lakes, and atmospheric aerosols. The aerosol interface, in particular, can play a crucial role in atmospheric chemistry. The adsorption of atmospheric species onto and into aerosols modifies their concentrations and chemistries. Moreover, the aerosol phase allows otherwise unlikely solution-phase chemistry to occur in the atmosphere. The effect of the air-water interface on these processes is not entirely known. This review summarizes recent theoretical investigations of the interactions of atmosphere species with the air-water interface, including reactant adsorption, photochemistry, and the spectroscopy of reactants at the water surface, with an emphasis on understanding differences between interfacial chemistries and the chemistries in both bulk solution and the gas phase. The results discussed here enable an understanding of fundamental concepts that lead to potential air-water interface effects, providing a framework to understand the effects of water surfaces on our atmosphere.

Impacts of cloud water droplets on the OH production rate from peroxide photolysis.

Understanding the difference between observed and modeled concentrations of HOx radicals in the troposphere is a current major issue in atmospheric chemistry. It is widely believed that existing atmospheric models miss a source of such radicals and several potential new sources have been proposed. In recent years, interest has increased on the role played by cloud droplets and organic aerosols. Computer modeling of ozone photolysis, for instance, has shown that atmospheric aqueous interfaces accelerate the associated OH production rate by as much as 3-4 orders of magnitude. Since methylhydroperoxide is a main source and sink of HOx radicals, especially at low NOx concentrations, it is fundamental to assess what is the influence of clouds on its chemistry and photochemistry. In this study, computer simulations for the photolysis of methylhydroperoxide at the air-water interface have been carried out showing that the OH production rate is severely enhanced, reaching a comparable level to ozone photolysis.

Effects of the substituents on the reactivity of carbonyl oxides. A theoretical study on the reaction of substituted carbonyl oxides with water.

The reactions between fifteen carbonyl oxides and water have been investigated with the aim of contributing to a better understanding of the effects of the substituents in the reactivity of carbonyl oxides. We have employed density functional theory and large scale ab initio methods (CCSD(T), CASSCF, and CASPT2), combined with transition state theory, to investigate the addition of water to carbonyl oxide and, for those carbonyl oxides having a methyl substituent in syn, the hydrogen transfer from the methyl group to the terminal oxygen of carbonyl oxide. In this case, the water acts as a catalyst and this reaction can contribute to the atmospheric formation of a hydroxyl radical. Carbonyl oxides with electron withdrawing substituents and zwitterionic character have low energy barriers and react fast, whereas carbonyl oxides with electron releasing substituents have high energy barriers and react slowly. The position of the substituents plays also an important role and carbonyl oxides having a hydrogen atom substituent in syn react faster than carbonyl oxides having a hydrogen atom substituent in anti. The differences in the reactivity of different substituted carbonyl oxides raise up to ten orders of magnitude and the branching ratios for the two different reactions investigated are also reported.

Role of vibrational anharmonicity in atmospheric radical hydrogen-bonded complexes.

Harmonic and anharmonic vibrational frequency calculations are reported for the most stable hydrogen bonded complexes formed between the hydroperoxyl radical and formic, acetic, nitric, and sulfuric acids which are of atmospheric interest. A comparison between the calculated IR spectra of the hydrogen bonded complexes with the corresponding separate monomers is also reported with the aim to facilitate a possible experimental identification of these complexes. The calculations have been carried out using the second-order vibrational perturbative treatment implemented by Barone applied to the PES obtained with the B3LYP functional using the 6-31+G(d,p) and 6-311+G(2d,2p) basis sets. Our calculations for the separate monomers predict vibrational frequencies with quite a good agreement with the experimental values. The anharmonic contribution results in differences of around 40 cm(-1) with respect to the harmonic values; although in some cases involving highly anharmonic modes, these differences can rise up to 300 and 450 cm(-1).

On the gas phase hydrogen bond complexes between formic acid and hydroperoxyl radical. A theoretical study.

We present a systematic study on the gas-phase hydrogen-bonded complexes formed between formic acid and hydroperoxyl radical, which has been carried out by using B3LYP and CCSD(T) theoretical approaches in connection with the 6-311+G(2df,2p) basis set. For all complexes we have employed the AIM theory by Bader and the NBO partition scheme by Weinhold to analyze the bonding features. We have found 17 stationary points, and 11 of them present a cyclic structure. Their computed stabilities vary from 0.3 to 11.3 kcal/mol, depending on several factors, such as involvement in the hydrogen bond interaction, the geometrical constraints, and the possible concurrence of further effects such as resonance-assisted hydrogen bonds or inductive effects. In addition, three stationary points correspond to transition structures involving a double proton-transfer process whose features are also analyzed.

Reproducibility of lateral excursive tooth contact in a semi-adjustable articulator depending on the type of lateral guidance.

The purposes of this study were (i) to compare the reproducibility of lateral tooth contacts of casts mounted in a semi-adjustable articulator when condylar guidance was set by different methods and (ii) to assess the margin of error of the variations of condylar guidance without changing lateral tooth contacts, depending on the type of lateral guidance. In subjects with different types of lateral guidance, intraoral lateral tooth contacts identified with occlusal registration strips were compared with those identified by use of a semi-adjustable articulator, setting the condylar guidance in four different ways: using protrusive wax wafers, by axiography and by adding and subtracting 5 degrees from the value of condylar guidance obtained by protrusive wax wafers. Tolerance to variations of condylar guidance without changing lateral tooth contacts was determined by increasing and decreasing the value of condylar guidance until lateral tooth contacts changed. Different ways of setting condylar guidance on a semi-adjustable articulator give rise to different values of condylar guidance in the same subject. The occlusal repercussions of these variations of condylar guidance values depend on the type of lateral guidance. Canine protection had the greatest tolerance to variations in the setting of condylar guidance without changing lateral occlusal contacts.

Variabilidad asistencial en la atención a politraumatizados por accidente de tráfico. Un estudio multicéntrico / Assistential variability in attending traffic accident polytraumatised patients. A multicentre study

Objetivo: Estudio multicéntrico transversal que evalúa la existencia de variabilidad asistencial en algunos aspectos de la asistencia básica prehospitalaria y hospitalaria a pacientes politraumatizados, por accidente de tráfico, en base a información recogida en un registro de pacientes traumáticos. Métodos: 508 pacientes han cumplido los siguientes criterios de inclusión: lesionado en accidente de tráfico, mayor de 18 años, Injury severity score (ISS) > 10, así como ingreso en UCI o fallecido en el hospital, en cinco centros sanitarios de Catalunya durante los años 1999-2000. Resultados: 1. Se han apreciado diferencias estadísticamente significativas en el tiempo de asistencia prehospitalaria tanto si se toma en cuenta la entidad prehospitalaria actuante como el centro hospitalario receptor. 2. El equipo médico actuante varía según centros y pacientes, estando compuesto habitualmente por dos a cuatro especialistas. Anestesiología, Intensivos o Emergencias pueden dirigir la renimación, mientras que Cirugía general, Cirugía ortopédica y Neurocirugía suelen ser el resto de componentes del equipo. 3. No se han observado diferencias estadísticamente significativas entre centros en el tiempo de práctica de la TAC craneal a pacientes con Glasgow Coma Score (GCS) <12, aunque se aprecia mayor retardo y dispersión cuando se toma en cuenta el tiempo desde el lugar del accidente. 4. El 45% de pacientes con diagnósticos de lesión en zona AIS 1 y 2 (cráneo, cara, cuello) al alta hospitalaria llevaban collarín cervical a la llegada al hospital. 5. No se aprecian diferencias estadísticamente significativas entre centros al evaluar el tiempo hasta el tratamiento de lesiones viscerales o fracturas abiertas. Conclusiones: Existe variabilidad asistencial en los pacientes politraumáticos por accidente de tráfico atendidos en los hospitales participantes. Es conveniente la implantación de guías clínicas de tratamiento, así como el desarrollo de un sistema de registro de politraumatizados y la homogeneización de los sistemas asistenciales (AU)

Aims: Cross-sectional multicentre study assessing the existence of assistential variability in some aspects of basic pre-hospitalary care to traffic accident polytramatised patients according to the information recorded a trauma patient registry. Method: Five hundred and eight patients fulfilled the following inclusion criteria: traffic accident victim, of full age, injury severity score (ISS)>10 and either ICU admission or death in hospital, at five Catalonian hospitals in the 1999-2000 period. Results: (1) Statistically significant differences have been observed in the duration of pre-hospitalary care considering both the pre-hospital care entily involved and the receiving hospital. (2) The acting medical team varies among the various hospitals and patients and is usually composed of two to four specialists. Anaesthesia, Intensive Care or Emergency Care may direct the reanimation/resuscitation team, the orther components of the team being usually General Surgery, Orthopaedic Surgery and Neurosurgery. (3) No statiscally significant differences were observed among the various hospitals in preforming a cranial CT scan in patients with Glasgow Coma Score (GCS) <12, althought a greater delay and scatter was seen when considering the time elapsed since the place of the accident. (4) Forty-five percent of the patients with lesions in the AIS 1 and 2 zones (cranium, face, neck) on hospital discharge carried a neck collar on arrival at the hospital. (5) No statiscally significant differences were observed among the various hospitals in the assessment of the time elapsed until management of visceral lesions or open fractures. Conclusions: Assistential variability exists in the care of traffic accident polytraumatised patients attended in the participating hospitals. It is convenient to establish clinical guidelines for treatment, as well as to develop a polytraumatism registry system and to homogenise the assistential systems (AU)

Seudofeocromocitoma / Pseudopheochromocytoma

El seudofeocromocitoma es una rara entidad recientemente definida. Ocurre en pacientes con el diagnóstico clínico de feocromocitoma pero sin el típico tumor medular suprarrenal, en lugar del que suele encontrarse un adenoma o un adenocarcinoma cortical suprarrenal. Describimos a una paciente con hipertensión arterial, hipersecreción de catecolaminas y hallazgos radiológicos compatibles con feocromocitoma, cuyo examen anatomopatológico fue concluyente de adenoma cortical. Revisamos la bibliografía referente al seudofeocromocitoma, la utilidad de los marcadores inmunohistoquímicos empleados en el estudio histopatológico de los tumores suprarrenales y, finalmente, se discute la patogenia de la diferenciación neuroendocrina de los tumores corticales (AU)

[Bronchial-associated lymphoid tissue lymphoma]. / Linfoma de tejido linfoide asociado al bronquio (BALT).

Two cases of non-Hodgkin's endobronchial or bronchial-associated lymphoid tissue lymphoma are reported; such cases are either extremely rare or underestimated. We emphasize the need to perform endoscopic examination in patients with lymphoma and clinical findings that suggest bronchial disease.

Cysteinyl-flavan-3-ol conjugates from grape procyanidins. Antioxidant and antiproliferative properties.

New bio-based antioxidant compounds have been obtained by depolymerisation of grape polymeric flavanols in the presence of cysteine. Their preparation and purification, as well as their antiradical/antioxidant and antiproliferative properties are reported. 4beta-(S-cysteinyl)epicatechin 5, 4beta-(S-cysteinyl)catechin 6 and 4beta-(S-cysteinyl)epicatechin 3-O-gallate 7 were efficiently purified from the crude depolymerised mixture by cation-exchange chromatography and preparative reversed-phase chromatography. The new compounds were more efficient than the underivatised (-)-epicatechin 1 as scavengers of the 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and weak growth inhibitors of human colon carcinoma HT29 cells. The order of antiradical and antiproliferative efficiency was 7 >5 approximately 6 >1, the same for both assays.

The ozonolysis of acetylene--a quantum chemical investigation.

The ozonolysis of acetylene was investigated using CCSD(T), CASPT2, and B3LYP-DFT in connection with a 6-311+G(2d,2p) basis set. The reaction is initiated by the formation of a van der Waals complex followed by a [4pi + 2pi] cycloaddition between ozone and acetylene (activation enthalpy DeltaH(a)(298) = 9.6 kcal/mol; experiment, 10.2 kcal/mol), yielding 1,2,3-trioxolene, which rapidly opens to alpha-ketocarbonyl oxide 5. Alternatively, an O atom can be transferred from ozone to acetylene (DeltaH(a)(298) = 15.6 kcal/mol), thus leading to formyl carbene, which can rearrange to oxirene or ketene. The key compound in the ozonolysis of acetylene is 5 because it is the starting point for the isomerization to the corresponding dioxirane 19 (DeltaH(a)(298) = 16.9 kcal/mol), for the cyclization to trioxabicyclo[2.1.0]pentane 10 (DeltaH(a)(298) = 19.5 kcal/mol), for the formation of hydroperoxy ketene 15 (DeltaH(a)(298) = 20.6 kcal/mol), and for the rearrangement to dioxetanone 9 (DeltaH(a)(298) = 23.6 kcal/mol). Compounds 19, 10, 15, and 9 rearrange or decompose with barriers between 13 and 16 kcal/mol to yield as major products formanhydride, glyoxal, formaldehyde, formic acid, and (to a minor extent) glyoxylic acid. Hence, the ozonolysis of acetylene possesses a very complicated reaction mechanism that deserves intensive experimental studies.

Tropospheric formation of hydroxymethyl hydroperoxide, formic acid, H2O2, and OH from carbonyl oxide in the presence of water vapor: a theoretical study of the reaction mechanism.

We have carried out a theoretical investigation of the gas-phase reaction mechanism of the H2COO+ H2O reaction, which is interesting for atmospheric purposes. The B3LYP method with the 6-31G(d,p) and 6-311 + G(2d,2p) basis sets was employed for the geometry optimization of the stationary points. Additionally, single-point CCSD(T)/6-311 + G(2d,2p) energy calculations have been done for the B3LYP/6-311 + G(2d,2p) optimized structures. The reaction begins with the formation of a hydrogen-bond complex that we have calculated to be 6 kcalmol(-1) more stable than the reactants. Then, the reaction follows two different channels. The first one leads to the formation of hydroxymethyl hydroperoxide (HMHP), for which we have calculated an activation barrier of deltaGa(298) = 11.3 kcalmol(-1), while the second one gives HCO + OH + H2O, with a calculated activation barrier of deltaGa(298) = 20.9 kcalmol(-1). This process corresponds to the water-catalyzed decomposition of H2COO, and its unimolecular decomposition has been previously reported in the literature. Additionally, we have also investigated the HMHP decomposition. We have found two reaction modes that yield HCOOH+H2O; one reaction mode leads to H2CO + H2O2 and a homolytic cleavage, which produces H2COOH + OH radicals. Furthermore, we have also investigated the water-assisted HMHP decomposition, which produces a catalytic effect of about 14 kcalmol(-1) in the process that leads to H2CO + H2O2.

[Psychosis as the initial manifestation of systemic lupus erythematosus: the role of lupus band test and anti-ribosomal antibodies]. / Psicosis como manifestación inicial de lupus eritematoso sistémico: valor de la prueba de la banda lúpica frente a los anticuerpos antirribosomales.

INTRODUCTION: Diffuse brain disease in systemic lupus erythematous (SLE) can be difficult to assess because of the sparse biological expression of the disorder, resulting in usually normal neuroimaging and laboratory findings. For this reason, it is likely that patients without a previous SLE diagnosis that presented initially with a pure psychiatric disorder, as psychosis or depression, can remain undiagnosed, and, in fact, they are exceptionally reported. As a biological marker, antiribosomal P protein antibodies have been closely related to SLE psychosis although their pathogenic role and specificity is under discussion. CLINICAL CASE: A young woman, without relevant medical history, presented with an acute psychotic catatonic picture, suspected organic in nature due to the existence of persistent mild CSF pleocytosis, while neuroimaging and laboratory studies were negative, including antinuclear and antiribosomal antibodies. Finally, a SLE diagnosis could be established because of a strong lupic band phenomenon in skin biopsy. CONCLUSIONS: It is important to maintain a high suspicion of SLE in acute psychotic patients, especially if atypical features are present. As the biological expression of the disorder in such cases may be elusive, we propose the study of lupus band in skin biopsy for these patients, regardless the absence of antiribosomal antibodies.

High prevalence of subclinical Sjögren's syndrome features in patients with autoimmune thyroid disease.

OBJECTIVE: To determine the prevalence of keratoconjunctivitis sicca and xerostomia related to Sjögren's syndrome (SS) in asymptomatic patients with diagnosed autoimmune thyroid diseases (AITD); and to investigate whether the immunopathologies of sialadenitis observed in AITD associated SS and primary SS are similar. METHODS: One hundred seventy-six patients diagnosed with AITD (88 with Graves' disease, 40 Hashimoto's thyroiditis, 48 primary myxedema) were tested for keratoconjunctivitis sicca (Schirmer's test and rose bengal staining) and for xerostomia (salivary scintigraphy and labial salivary gland biopsy). Immunohistopathological studies were performed on cryostat sections of bucal mucosa biopsies using antibodies to CD3, CD4, CD8, CD20, CD14, CD25, LFA-1, ICAM-3 HLA class II, tumor necrosis factor-alpha, interleukin 1, and interferon-gamma. RESULTS: Nineteen of 52 (37%) patients with AITD fulfilled the criteria for xerostomia and 39/170 (23%) for keratoconjunctivitis sicca. Features of SS were diagnosed in 43 of 176 (24%) patients with AITD, with similar prevalence in Graves' (20%). Hashimoto's thyroiditis (27%), and primary myxedema (29%). In AITD associated SS, infiltrating lymphocytes were mainly CD3+ T lymphocytes, with a CD4/CD8 ratio of 2:1. In most patients infiltrating lymphocytes expressed activation markers, HLA class II molecules, and interleukin 2 receptor (CD25). In some patients HLA class II was inappropriately expressed in the epithelial gland cells. CONCLUSION: The finding that a third of patients with AITD have SS features confirms that AITD and SS are mutually associated. Together with the similarity of immunopathology of sialadenitis in AITD associated SS in primary SS, this supports the theory that SS and AITD are 2 autoimmune diseases closely related pathogenetically.

[Gestational diabetes: the use of an intensive treatment program at the regional level]. / Diabetes gestacional: aplicación de un programa de tratamiento intensificado a nivel comarcal.

In this study the results are shown of the application of an intensified treatment program of Gestational Diabetes (GD) in a regional setting. From January 1991 to June 1995, 115 women with GD were attended at Mútua Hospital in Terrassa; 62.6% of them required insulin to optimize the metabolic control. When insulin dependent women were compared with non insulin dependent women, diagnosis was earlier; age, progestational age, serum glucose in the O'Sullivan test and diagnostic basal serum glucose in oral overload (GOO) were higher. Regarding perinatal results, the incidence of gestational hypertensive disturbances, hydramnios, and urinary tract infections were 7%, 1.7%, and 8%, respectively. Perinatal mortality was 0.86%. Delivery occurred after 37 weeks in 96.5% of cases and the cesarean section was performed in 26%; nevertheless, this rate was similar to that in the obstetric population attended at this institution (25%). Birth weight was high for gestational age in 7.8% of newborns (NB) and low in 2.5%. Factors associated with fetal weight included progestational maternal weight, ponderal increase during pregnancy and metabolic control (HbA1c). The present study suggests that the application of an intensified treatment program for GD can be carried out in a regional setting and with overall successful results.

Prevalence of osteomyelitis in non-healing diabetic foot ulcers: usefulness of radiologic and scintigraphic findings.

The study was conducted in order to assess the prevalence of osteomyelitis and the predictive value of radiographic (xR) and combined Tc 99-bone and leukocyte scanning (CS) findings in diabetic foot ulcers that met criteria for hospital admission (FUH). Out of 150 episodes of ulceration managed in an outpatient basis, 33 (in 28 NIDDM patients) requiring admission were evaluated. In all cases plain xR and CS were carried out. Seventeen episodes (51.5%) had a good outcome (healed or improving, at the time of the last follow up). Osteomyelitis was found in 21 episodes and 14 (66.6%) of them required an amputation. In 13 cases where xR showed characteristic radiologic changes of osteomyelitis (11 of them had a positive CS) 11 (84.6%) underwent an amputation. However, when osteomyelitis was diagnosed only by a positive CS, only 3/8 (37.5%) required a toe amputation. Severe peripheral vasculopathy was present in 44% of cases who required amputation and only in 17.6% of those who did not. We conclude that in FU underlying osteomyelitis is frequent and associated to a higher amputation rate than when no bone infection is identified (66.6 vs 17%), even when corrected for vascular status (OR 11, CI 95% 1.65-74.2), with a worse outcome when xR changes are already present.