Cycloaddition between nitrogen-doped graphene (6π-component) and benzene (4π-component): a theoretical approach using density functional theory with vdW-DF correction.

The interaction between nitrogen-doped graphene defects (N3V1 and N4V2 pyridinic, and N3V1 and N3V3 pyrrolic) and benzene have been investigated by applying density functional theory (DFT), together with the vdW-DF correction. We discovered that only the N3V3 pyrrolic defect is a reactive site (6π-component), forming a cycloadduct with benzene (4π-component) that has energy barriers below 154.38 kJ mol-1 (1.60 eV). The conduction and valence bands (HOMO and LUMO) for N3V3 form a degenerate pair of orbitals at the gamma point, with the same ionization potential (IP) and electron affinity (EA). Likewise, inspection of the orbital symmetries for both systems confirms that these must undergo concerted reactions based on the Woodward and Hoffmann principles of orbital symmetry, with the appropriate orbital occupancies. This is the first time that substitutionally doped graphene has been demonstrated to participate as a 6π-component for cycloaddition reactions with benzene.

Effect of ultrasonic irradiation power on sonochemical synthesis of gold nanoparticles.

In this work, optimized size distribution and optical properties in the colloidal synthesis of gold nanoparticles (GNPs) were obtained using a proposed ultrasonic irradiation assisted Turkevich-Frens method. The effect of three nominal ultrasound (20 kHz) irradiation powers: 60, 150, and 210 W have been analyzed as size and shape control parameters. The GNPs colloidal solutions were obtained from chloroauric acid (HAuCl4) and trisodium citrate (C6H5Na3O7·2H2O) under continuous irradiation for 1 h without any additional heat or stirring. The surface plasmon resonance (SPR) was monitored in the UV-Vis spectra every 10 min to found the optimal time for localized SPR wavelength (λLSPR), and the 210 sample procedure has reduced the λLSPR localization at 20 min, while 150 and 60 samples have showed λLSPR at 60 min. The nucleation and growth of GNPs showed changes in shape and size distribution associated with physical (cavitation, temperature) and chemical (radical generation, pH) conditions in the aqueous solution. The results showed quasi-spherical GNPs as pentakis dodecahedron (λLSPR = 560 nm), triakis icosahedron (λLSPR = 535 nm), and tetrakis hexahedron (λLSPR = 525 nm) in a size range from 12 to 16 nm. Chemical effects of ultrasound irradiation were suggested in the disproportionation process, electrons of AuCl2- are rapidly exchanged through the gold surface. After AuCl4- and Cl- were desorbed, a tetrachloroaurate complex was recycled for the two-electron reduction by citrate, aurophilic interaction between complexes AuCl2-, electrons exchange, and gold seeds, the deposition of new gold atoms on the surface promoting the growth of GNPs. These mechanisms are enhanced by the effects of ultrasound, such as cavitation and transmitted energy into the solution. These results show that the plasmonic response from the reported GNPs can be tuned using a simple methodology with minimum infrastructure requirements. Moreover, the production method could be easily scalable to meet industrial manufacturing needs.

Análisis morfométrico e índices corporales del capitán de la sabana / Morphometric analysis and body indexes of the catfish (Eremophilus mutisii)

RESUMEN Con el objetivo de caracterizar la morfometría e índices corporales de Eremophilus mutisii, se usaron treinta y tres peces (27 hembras y 6 machos) provenientes del río Bogotá, específicamente de la región de Suesca. La relación de aspecto de la aleta caudal se determinó mediante el software de análisis de imágenes ImageJ®. Se calculó el índice gonadosomático, hepatosomático y rendimiento en canal para cada pez. Para el análisis de los datos se usaron correlaciones, regresiones y técnicas de análisis multivariado (análisis discriminante canónico). Como resultado del estudio se encontró que el sexo no afecta la forma del cuerpo de los peces. La relación entre la longitud y el peso se ajustó para cada sexo. La relación de aspecto de la aleta caudal presentó un promedio de 1,57 lo que sugiere que la especie presenta hábito sedentario o de natación lenta. El índice gonadosomático de las hembras en maduración (media: 14,43%, rango: 8,84% a 23,22%) aumentó en función del peso corporal y fue mayor que el de los machos (media: 5,32%, rango: 2,31% a 8,29%). Por lo tanto, el rendimiento de la carcasa fue menor en las hembras en maduración. La media del índice hepatosomático para hembras fue 0,86% (rango: 0,43% a 1,88%) y para machos fue 0,63% (rango: 0,39% a 1,09%). En conclusión, Eremophilus mutisii es una especie sedentaria y las hembras se caracterizarán por presentar mayor índice gonadosomático y menor rendimiento en carcasa que los machos.

ABSTRACT With the aim of characterizing the morphometry and body indexes of Eremophilus mutisii, thirty-three fishes (27 females and 6 males) coming from the Bogotá river, specifically of the Suesca region, were used. The aspect ratio of the caudal fin was determined with the aid of the image analysis software ImageJ®. Gonadosomatic and hepatosomatic indexes and carcass yield were determined for each fish. Correlation, regression and multivariate (canonical discriminant analysis) techniques were used for data analysis. Results indicated that sex does not affect the body shape of the fishes. The relationship between length and weight was fitted for each sex. The average aspect ratio of the caudal fin was 1.57, which suggests that the species has sedentary habits or slow swimming. The gonadosomatic index of the maturing females (mean: 14.43 %; range: 8.84 % to 23.22 %) increased as a function of body weight and was greater than in males (mean: 5.32 %; range: 2.31 % to 8.29 %). Therefore, the carcass yield was lower in maturing females than in males. The mean of the hepatosomatic index for females was 0.86 % (range: 0.43 % to 1.88 %) and for males was 0.63 % (range: 0.39 % to 1.09 %). As a conclusion, Eremophilus mutisii is a sedentary fish species, and females exhibit greater gonadosomatic index and lower carcass yield than males.

Highly porous multiwalled carbon nanotube buckypaper using electrospun polyacrylonitrile nanofiber as a sacrificial material.

Polyacrylonitrile (PAN) was solubilized in N,N-dimethyl formamide (DMF) and the electrospinning process has been employed to obtain PAN nanofibers (PF). Multiwalled carbon nanotubes (MWCNT) were dispersed with the aid of Triton X-100 surfactant and subsequently centrifugated. Buckypapers (BP/PF) were prepared by vacuum filtration procedure of MWCNT suspension supernatant stacking four PF layers over a nylon membrane. The PF removal was carried out by immersing the BP/PF system in DMF and removal periods of 10 and 30 min were evaluated. Scanning electron microscopy (SEM) has not shown any PAN residue in the MWCNT network resulting in highly porous BP. However, by Fourier transform infrared spectroscopy (FT-IR) a PAN band was found around of 2243 cm-1 corresponding to nitrile group (C≡N). Besides, PAN leftover was evidenced by thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HR-TEM), electrical characterization through four-point probe, nitrogen adsorption at 77 K, and X-ray diffraction (XRD).

Werner's Syndrome: Understanding the Phenotype of Premature Aging-First Case Described in Colombia.

Werner's syndrome (WS) is an autosomal recessive genetic disease, which is mainly characterized by scleroderma-like skin changes, juvenile cataracts, short stature, and signs of premature aging. We report a case of a 48-year-old male patient, who presents with cardinal signs of WS including high-pitched voice, sclerotic skin lesions mainly on feet, premature greying of scalp hair, bilateral cataracts, and "bird-like" facial appearance. In addition, the patient presents other clinical characteristics observed in patients with WS such as short stature, type 2 diabetes mellitus, hypogonadism, parental consanguinity, and a history of a sibling with similar clinical characteristics. WRN gene sequencing identified the homozygous pathogenic variant NM_00553.4: c.2581C>T (NP_000544.2: pGln861Ter). This is the first case of WS reported in the Colombian population. We report this case to avoid misdiagnosis of this infrequent condition and allow timely identification of potential complications associated with premature aging, especially malignancies, cardiovascular and metabolic diseases.

Changes to the dissociation barrier of H2 due to buckling induced by a chemisorbed hydrogen on a doped graphene surface.

An effectiveway of enhancing hydrogen storage on adsorbent materials can be induced by the hydrogen spill-over mechanism, although to date there is no general consensus which satisfactorily explains the mechanism. In this work, a possible reaction path to explain hydrogen adsorption is shown. Density-functional calculations were used to study the dissociation of molecular hydrogen near to a stressed region, as a consequence of chemisorbed hydrogen at the graphene-nitrogen surface. We found that as a result of the buckling induced by the chemisorbed hydrogen, the dissociation barrier of molecular hydrogen diminished by 0.84 eV. The chemisorbed hydrogen is the final state in the spill-over mechanism on a graphene-nitrogen decorated with palladium clusters. This effect helps to create hydrogen nanoislands that may change the diffusion and detrapping of H. An electronic structure analysis suggests that these systems occasionally present metallic or semiconductor behavior. Graphical Abstract Hydrogen dissociation and adsorption process via buckling defect.

Does the menopausal status of female gynecologists affect their prescription of menopausal hormone therapy?

OBJECTIVE: To evaluate whether menopausal status and symptoms among female gynecologists would influence their clinical behavior related to menopausal hormone therapy (MHT). METHODS: Female gynecologists of 11 Latin American countries were requested to fill out the Menopause Rating Scale and a questionnaire containing personal information and that related to MHT use. RESULTS: A total of 818 gynecologists accepted to participate (86.4%). Overall, the mean age was 45.0 ± 10.7 years, 32.2% were postmenopausal, and 17.6% worked in an academic position; 81.8% reported that they would use MHT if they have symptoms, regardless of menopausal status. Academic gynecologists favor personal MHT use at a higher rate (p = 0.04) and have a higher MHT prescription rate as compared to non-academic ones (p = 0.0001). The same trend was observed among post- as compared to premenopausal ones (p = 0.01) and among those who had hysterectomy alone as compared to those experiencing natural menopause (p = 0.002). The presence of menopausal symptoms did not influence their MHT prescription. Current use of MHT and alternative therapy was higher among post- than premenopausal gynecologists (both, p = 0.0001) and among those who had undergone hysterectomy than those experiencing natural menopause. A 38.5% perceived breast cancer as the main risk related to MHT, and a high proportion prescribed non-hormonal drugs (86.4%) or alternative therapies (84.5%). CONCLUSION: Most female gynecologists in this survey would use MHT if menopausal symptoms were present. Postmenopausal physicians use MHT and prescribe it to their symptomatic patients at a higher rate than premenopausal physicians.

Cuidado crítico en la paciente obstétrica. Complicaciones, intervenciones y desenlace maternofetal / Critical care in the obstetric patient: Complications, interventions and maternal and fetal outcomes

Introducción A pesar de los grandes avances de la medicina, aún se siguen presentando muertes por causas obstétricas en todo el mundo, muchas de estas prevenibles, dado que existen fallas en el reconocimiento de las patologías obstétricas y no obstétricas que pueden comprometer el embarazo. Objetivo Describir las características de la paciente obstétrica crítica, su comportamiento, intervenciones y desenlace maternofetal. Materiales y métodos Estudio descriptivo retrospectivo de pacientes obstétricas que ingresaron en la Unidad de Cuidados Intensivos (UCI) de la Clínica de Maternidad Rafael Calvo de Cartagena, Colombia, durante un lapso de 28 meses. Se registraron las causas de ingreso, características de las pacientes, complicaciones por sistemas, intervenciones realizadas y mortalidad materna y perinatal. Resultados Ingresaron en el momento del estudio 214 pacientes. La edad promedia fue 24 años (DE±7,2). La principal causa de ingreso fueron los trastornos hipertensivos asociados al embarazo. La mediana de estancia en UCI fue de 4, con un rango intercuartil de 2–6 días. El 64,5% de las pacientes eran multíparas y solo el 50,5% tenía control prenatal. El 14% ingresaron embarazadas en la unidad. El 60% de las pacientes requirieron algún tipo de intervención. Las principales complicaciones que se encontraron fueron renales. La mortalidad del grupo estudiado fue del 8,4%. El 100% era multípara, el 61,1% no tenía control prenatal y el 27,7% era menor de 20 años. La mortalidad perinatal fue del 26,6%. Conclusión Nuestra UCI tiene un alto número de ingresos de pacientes obstétricas. Se encontró que las pacientes con peor desenlace fueron multíparas, sin control prenatal y requirieron más intervenciones (AU)

Abstract: Introduction: Despite major advances in medicine, deaths due to obstetric causes still occurworldwide. Many of these deaths are preventable since they are caused by failure to recognizeobstetric and non-obstetric disorders that can compromise pregnancy.Objectives: To describe the characteristics of critically-ill obstetric patients, as well ascomplications, interventions and maternal and fetal outcomes. Materials and methods: A retrospective, descriptive study of obstetric patients admitted intothe intensive care unit (ICU) of the Rafael Calvo Maternity Clinic of Cartagena, Colombia, overa 28-month period was performed. Causes for admission, patient characteristics, complicationsby organ system, the interventions performed, and maternal and perinatal mortality wereregistered. Results: A total of 214 patients were included in the study. The mean age was 24 years (SD±7.2).The main cause for admission was pregnancy-induced hypertension. The median length of ICUstay was 4 days (interquartile range: 2—6 days). Of these patients, 64.5% were multiparousand only 50.5% had documented antenatal care. Fourteen percent were admitted to the ICU while still pregnant. Sixty percent of the patients required some type of intervention. The maincomplications were renal. Mortality was 8.4%. Of the patients who died, all were multiparous,61.1% had no antenatal care and 27.7% were aged less than 20 years. Perinatal mortality was26.6%.Conclusions: Our ICU has a high admissions rate of obstetric patients. We found that patientswith poor outcomes were multiparous, without antenatal care and required a greater numberof interventions (AU)

How to recognize and workaround pitfalls in QSAR studies: a critical review.

Quantitative Structure-Activity Relationships (QSAR) are based on the hypothesis that changes in molecular structure reflect proportional changes in the observed response or biological activity. In order to successfully conduct QSAR studies certain conditions have to be met that are not frequently reported in the literature. This suggests that some authors are not aware of the principle flaws, occasional shortcomings, and circumstantial downsides of QSAR methods. The present paper focuses on prerequisites to set up correct models and on limitations of model applications. Their implications are systematically described and illustrated as pitfalls that have strong implications in QSAR, and possible solutions are suggested. The paper is focused on small scale 2D- and 3D-QSAR studies for lead optimization. The work is enriched with comprehensive comments and non-mathematical explanations for the computer practitioner in Medicinal Chemistry.

Soporte nutricional en el enfermo paliativo

No disponible

Cytological effects of 60 Hz magnetic fields on human lymphocytes in vitro: sister-chromatid exchanges, cell kinetics and mitotic rate.

Incubation for 72 h of human peripheral blood cultures in the presence of 60 Hz sinusoidal magnetic fields (MF) at magnetic flux densities of 1.0, 1.5, and 2.0 mT led to stimulation of lymphocyte proliferation but had no influence on the frequency of sister-chromatid exchanges (SCE). The cytotoxic potential of MF combined with the mutagen Mitomycin-C also was analyzed. An opposite effect between MF exposure and Mitomycin-C treatment in terms of cell kinetics and mitotic rate was found, whereas no variation in SCE frequency was observed for this coexposure condition.

Acute effects of 60-Hz electromagnetic fields on ex vivo murine lymphocyte and macrophage functions, and in vitro tumor cell growth.

Electromagnetic fields (EMFs) have been associated with impairing health. There are data that associate EMFs exposure to incidence of cancer, but there are conflicting results between epidemiological and laboratory studies. Similarly studies on the effect of EMF on the immune system have produced variable results. In the present study, we evaluated the acute effects of 60 Hz EMFs exposure at 1.0 mT, on proliferation of murine thymic lymphocytes, production of nitric oxide and phagocytosis of Candida albicans by peritoneal murine macrophages, as well as the effect of 8 h/day of EMF exposure during 6 days on proliferation of murine lymphoma L5178Y-R cell growth. We observed that exposure to EMF did not alter lymphocyte and macrophage functions, and did not affect in vitro cell growth of the murine lymphoma cell line L5178Y-R.

Prevalencia del síndrome de fibromialgia en pacientes oncológicos. Estudio comparativo / Prevalence of the fibromyalgia syndrome in oncologic patients. Comparative study

Antecedentes: El dolor es un síntoma que se presenta frecuentemente en el paciente oncológico. Es el producto de diversos mecanismos fisiopatológicos, los cuales pueden o no estar relacionados con el cáncer. El síndrome de fibromialgia señala dolor musculoesquelético generalizado que puede ser manifestado por los pacientes con cáncer. Objetivo: Obtener la prevalencia del síndrome de fibromialgia en los enfermos con cáncer. Paciantes y métodos: En estudio observacional, prospectivo, comparativo, pareado por edad y sexo en corte transversal que incluyó 50 sujetos con diagnóstico histológico de neoplasia y 50 pacientes no oncológicos. El diagnóstico de fibromialgia fue fundamentado según los lineamientos del Colegio Americano de Reumatología, que incluyen: a) dolor osteomuscular generalizado, ubicado en más de tres regiones corporales distintas y con duración no menor a tres meses, y b) detección de al menos 11 puntos positivos, de los 18 establecidos para fibrositis. Resultados: Cada grupo incluyó 26 hombres (52 por ciento) y 24 mujeres (48 por ciento) con edad promedio de 52.84 ñ 14.7 años (límites de 16 a 82). En los pacientes oncológicos, la escala promedio de Karnofsky fue 80.6. ñ 13.4, con límites de 50 a 100 puntos. Veintitrés pacientes oncológicos (46 por ciento) y cuatro no oncológicos (8 por ciento) cumplieron criterios para fibromialgia, p < 0.001. El síndrome de fibromialgia fue más frecuente en mujeres (82.6 por ciento), con edad promedio de 53 años, escalas de Karnofsky bajas 73.9 ñ 12 por ciento versus 86.3 ñ 11.8 por ciento, p < 0.001 y estadios clínicos tumorales avanzados, p = 0.001. Se observó depresión en 19 pacientes con cáncer (82 por ciento) y en dos no oncológicos (50 por ciento), p = 0.05. Conclusiones: La prevalencia del síndrome de fibromialgia fue alta en pacientes con cáncer; predominó en mujeres; se asoció a escalas de karnofsky bajas y a estadios tumorales avanzados. La presencia de depresión fue más frecuente en pacientes oncológicos con fibromialgia

Application of enzyme-linked immunosorbent assay for epidemiological studies of diseases of livestock in the tropics of Mexico.

This study was conducted at the Centre for Research, Teaching and Extension in Tropical Livestock (Centro de Investigación, Enseñanza y Extensión en Ganadería Tropical) of the Faculty of Veterinary Medicine of the National Autonomous University of Mexico. During the latter part of 1986 and throughout 1988 and 1989, the herd of Holstein x zebu cattle at the University was tested for IgG antibodies to twenty-one viral, bacterial, rickettsial and parasitic agents. Antigens prepared from twenty infectious disease agents were used as the solid phase in an enzyme-linked immunosorbent assay, and the agar gel immunodiffusion procedure was used to test for antibodies against bovine leukaemia virus. The prevalence of IgG antibodies was high (> 50%) for bluetongue virus, Anaplasma marginale and Mycoplasma bovis. Antibodies to Brucella abortus were absent and antibodies against bovine virus diarrhoea virus and infectious bovine rhinotracheitis virus showed a very low prevalence (< 5%). Antibodies to fifteen other antigens showed intermediate prevalence (15-46%). Antibodies to Campylobacter fetus, A. marginale, bluetongue virus, bovine leukaemia virus and Haemophilus somnus displayed seasonal variations. Levels of antibody to bovine leukaemia virus, M. bovis and Listeria monocytogenes exhibited increasing secular trends while antibodies to bovine virus diarrhoea virus and C. fetus showed declining trends. Prevalence of antibodies increased with the age of animals tested. No consistent difference in antibody prevalence was found between three genotypic groups examined.

Autosomal recessive microcephaly associated with chorioretinopathy.

Two sisters and their brother affected with microcephaly, microphthalmia, chorioretinal degeneration, and optic atrophy were studied. Besides the clinical features derived from the main abnormalities, nanosomy and cutis marmorata were found in the three patients. Both parents and three other sibs were normal. Possible intrauterine non-genetic etiologic factors (X-rays, toxoplasmosis, cytomegalovirus) which can lead to phenocopies were investigated with negative results. Based on these and previous observations, it seems clear that a distinct form of autosomal recessive microcephaly associated with chorioretinal degeneration can be separated from the heterogenous group of entities which presents microcephaly.