Modeling Photodissociation: Quantum Dynamics Simulations of Methanol.

A comprehensive computational study of the gas-phase photodissociation dynamics of methanol is presented. Using a multiconfigurational active space based method (RASSCF) to obtain multidimensional potential energy surfaces (PESs) on-the-fly, direct quantum dynamics simulations were run using the variational multi-configurational Gaussian method (DD-vMCG). Different initial excitation energies were simulated to investigate the dependence of the branching ratios on the electronic state being populated. A detailed mechanistic explanation is provided for the observed differences with respect to the excitation energy. Population of the lowest lying excited state of methanol leads to rapid hydroxyl hydrogen loss as the main dissociation channel. This is rationalized by the strongly dissociative nature of the PES cut along the O-H stretching coordinate, confirmed by the broad feature in the absorption spectrum. In contrast, more energetic excitations lead mainly to C-O bond breaking. Again, analysis of the diabatic surfaces offers a clear explanation in terms of the nature of the electronic states involved and the coupling between them. The type of calculations presented, as well as the subsequent analysis of the results, should be seen as a general workflow for the modeling of photochemical reactions.

Altered endothelial dysfunction-related miRs in plasma from ME/CFS patients.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disease characterized by unexplained debilitating fatigue. Although the etiology is unknown, evidence supports immunological abnormalities, such as persistent inflammation and immune-cell activation, in a subset of patients. Since the interplay between inflammation and vascular alterations is well-established in other diseases, endothelial dysfunction has emerged as another player in ME/CFS pathogenesis. Endothelial nitric oxide synthase (eNOS) generates nitric oxide (NO) that maintains endothelial homeostasis. eNOS is activated by silent information regulator 1 (Sirt1), an anti-inflammatory protein. Despite its relevance, no study has addressed the Sirt1/eNOS axis in ME/CFS. The interest in circulating microRNAs (miRs) as potential biomarkers in ME/CFS has increased in recent years. Accordingly, we analyze a set of miRs reported to modulate the Sirt1/eNOS axis using plasma from ME/CFS patients. Our results show that miR-21, miR-34a, miR-92a, miR-126, and miR-200c are jointly increased in ME/CFS patients compared to healthy controls. A similar finding was obtained when analyzing public miR data on peripheral blood mononuclear cells. Bioinformatics analysis shows that endothelial function-related signaling pathways are associated with these miRs, including oxidative stress and oxygen regulation. Interestingly, histone deacetylase 1, a protein responsible for epigenetic regulations, represented the most relevant node within the network. In conclusion, our study provides a basis to find endothelial dysfunction-related biomarkers and explore novel targets in ME/CFS.

[Effect of transdermal administration of 17-beta estradiol on the release of growth hormone by growth hormone liberating hormone (GH-RH-1-29) in climacteric women before and after treatment]. / Influencia de la administración transdérmica de 17-beta estradiol sobre la liberación de hormona de crecimiento mediante la hormona liberadora de la hormona de crecimiento (GH-RH-1-29) en mujeres climatéricas pre y postratamiento.

BACKGROUND: Great interest has sparked recently the role that plays the changes that the growth hormone undergoes in the menopausal woman, specially its involvement in the central nervous, cardiovascular, genitourinary, digestive and osteomuscular systems. OBJECTIVE: To evaluate the influence of transdermal administration of 17-beta estradiol on growth hormone secretion in menopausal women before and after treatment under the stimulus of growth-hormonereleasing hormone (GH-RH). MATERIAL AND METHODS: We studied 5 patients with a mean age of 51 +/- 4.1 yr. with clinical and biochemical evidence of menopause. Evolution time 5.4 +/- 4.61 (range: 1-13 yr.). We monitored the pulsatility of GH during the first 120 minutes and 3 hours after the administration of the GHRH-1-29-NH2, i.v. bolus (50 micrograms). There were obtained every 15 minutes for the determination of GH levels before and after the stimulus. Immediately thereafter hormone replacement therapy was initiated with transdermal beta-estradiol with 50 micrograms patches twice a week. Clinical evaluations and hormone dynamics with OHRH-1-29 were performed at baseline and at 1,3 and 6 months from the start of therapy as described previously. RESULTS: GH pulsatility before estrogen replacement therapy (ERT) in these 5 patients was: X: 0.48 +/- 0.22, 0.38 +/- 0.17, 0.45 +/- 0.25 and 0.29 (at baseline, 1, 3 and 6 months respectively) and 2.74 +/- o 1.21; 3.48 +/- 1.32 (p > 0.05) 4.91 +/- 1.57 (p < 0.05) and 6.04 +/- 1.69 (p < 0.05) (p in relation to baseline) post stimulus with GH-RH-1-29 at baseline 1, 3 and 6 months respectively after transdermal estrogen therapy. Gonadotrophins basal serum levels fall from X: 54.68 +/- 27 to 33.20 +/- 11.23 and 40.48 +/- 12 to 28.30 +/- 6.70 (FSH and LH respectively). Estradiol serum level were from 1.82 +/- 4.06 to 25.95 +/- 5.96 before and after treatment, respectively. COMMENTS AND CONCLUSIONS: These results demonstrate that transdermal estrogen therapy does not modify the pulsatility of growth hormone but it does increase the magnitude of response to the stimulus with GH-RH-1-29 proportional to the time of treatment. We consider that this tendency to increase the production of growth hormone could be explained by an endogenous deficit of growth hormone releasing hormone due to a number of factors including the lack of adequate estrogen serum levels in menopausal women. More investigations will be needed to support this hypothesis and to bring forth a new understanding of menopause and its treatment.

Anillos vasculares. Experiencia en el Hospital del Niño / Vascular rings. Experience at the Children's Hospital

The authors present the clinical findings, diagnosis and treatment of vascular rings and their review of 12 cases treated between 1973 and 1998 at the Hospital del Niño, Panama city, Panama

[Vascular rings. Experience at the Children's Hospital]. / Anillos vasculares. Experiencia en el Hospital del Niño.

The authors present the clinical findings, diagnosis and treatment of vascular rings and their review of 12 cases treated between 1973 and 1998 at the Hospital del Niño, Panama city, Panama.

Amperometric flow-injection method for the assay of l-ascorbic acid based on the photochemical reduction of Methylene Blue.

Ascorbic acid (AA) is determined by amperometric detection based on the photochemical reduction of Methylene Blue (MB(+)) in 0.1 M phthalate buffer at pH 3.8. In this medium, MB(+) using flow-injection analysis. The carrier stream is 1 mM MB(+) is reduced quasi-reversibly at a glassy carbon electrode at -0.34 V vs. Ag/AgCl, while AA is oxidized irreversibly at about 0.3 V. The reactor is irradiated with a 500 W halogen lamp to facilitate the development of the photochemical reaction. A laboratory-built wall-jet electrode system was used. The Leucomethylene Blue formed in the reaction is detected at +0.050 V. At 2.2 ml min(-1) and using a sample loop of 43 mul, the method allows the determination of AA in the range 5.0-90.0 mug ml(-1), with a relative standard deviation of 1.3-4.8%, a detection limit of 1.9 mug ml(-1) and a sampling frequency of 45-50 h(-1).

Use of photochemical reactions in flow injection: determination of oxalate in urine.

The use of photochemical reactions in flow injection (FI) is reported. The irradiation of an FI reactor with a suitable source facilitates the development of the iron(III)-oxalate reaction, allowing the amperometric determination of the anion in the range 1.0-13.0 micrograms ml-1, with a relative standard deviation of 1.1% and a sampling frequency of 40 h-1. The proposed method was applied successfully to the determination of oxalate in urine samples.

Patterns of acute respiratory tract infection in children: a longitudinal study in a depressed community in Metro Manila.

The incidences of acute respiratory tract infection (ARI) and acute lower respiratory infection (ALRI) were 6.1 and 0.5 per child-year, respectively, in children less than 5 years old in a depressed urban community in Manila. The peak age-specific incidence occurred in those children 6-23 months old for ARI and 6-11 months old for ALRI. Age less than 2 years, malnutrition, household crowding, and parental smoking were associated with a statistically significant, though modest, increase in ARI morbidity. The crude mortality rate was 14.3 per 1,000 children 0-4 years old, with a corresponding ARI-specific mortality rate of 8.9 per 1,000. The prevalence of viral infection was 32.8 and that of bacteremic ALRI was 6.7 per 1,000 children with moderate ALRI. Respiratory syncytial virus was the predominant viral pathogen, while Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus were the most frequently isolated bacterial pathogens. Transmission of respiratory pathogens in depressed communities, facilitated by inadequate housing, inaccessible health services, and prevalent malnutrition, will continue unless meaningful socioeconomic improvement is realized.

Etiology of acute lower respiratory tract infection in children from Alabang, Metro Manila.

The etiology of acute lower respiratory tract infection (ALRI) was identified in 235 (43.8%) of 537 hospitalized children less than 5 years of age. Clinical evidence of measles was found in 258 (48.0%) patients, of whom 59 had a second viral infection. A viral agent was identified in an additional 121 patients, so that a total of 379 (70.6%) had viral infections. After measles, respiratory syncytial virus was the most common respiratory virus. Bacteremia was noted in 72 children (13.4%), occurring as frequently in children with measles (14.8%) as in those without (12.1%); Haemophilus influenzae and Salmonella typhi were predominant in the former, and H. influenzae, Staphylococcus aureus, and Streptococcus pneumoniae were prominent in the latter. The presence of bacterial antigen in urine was not helpful in identifying bacterial infection. Extrapulmonary and intrapleural complications, concomitant measles, complicated ALRI, female gender, and malnutrition were associated with increased mortality among children with ALRI. The importance of measles immunization, vitamin A supplementation for alleviation of defects associated with malnutrition, and timely antimicrobial therapy is emphasized.

Determinants of morbidity and mortality due to acute respiratory infections: implications for intervention.

Acute respiratory infections (ARI) were monitored every two weeks in an urban community in Metro Manila, Philippines, to determine the incidence and risk factors for ARI morbidity. Hospitalized children with acute lower-respiratory-tract infection (ALRI) were studied to determine case-fatality rates (CFR) and predictors for mortality. Incidence rates were highest in infants, 3.2-4.0 per person, followed by children one to four years of age, with corresponding rates of 3.0-3.4 per person. The risk factors for ARI morbidity were low socioeconomic status and age less than one year. A CFR of 5% in children with ALRI was observed. Malnutrition and a positive culture of blood were significant risk factors for mortality. These identified risk factors underscore the value of primary health care interventions, such as the standard ARI case management, immunization, health education, promotion of breast-feeding, and vitamin A supplementation, as strategies for reducing ARI mortality in developing countries.

A comparison of the effectiveness of hand scaling and ultrasonic debridement in furcations as evaluated by differential dark-field microscopy.

There have been no previous reports in the literature comparing the effects of hand scaling with ultrasonic debridement in furcations, or which have used dark-field microscopy for this comparison. The purpose of this study was to compare the efficacy of these two modes of debridement in various classes of furcations, using gingival crevicular fluid flow and dark-field microscopy as parameters. A total of 33 furcated molars were evaluated. Results indicated that both hand scaling and ultrasonic debridement were equally effective in Class I furcations in changing the gingival fluid flow and bacterial proportions to those of a healthy state. In contrast, ultrasonic debridement was significantly more effective than hand scaling in Class II and Class III furcations in altering these parameters.