PREPARATION OF SILVER AND GOLD NANOPARTICLES: A SIMPLE METHOD TO INTRODUCE NANOTECHNOLOGY INTO TEACHING LABORATORIES.

PREPARATION OF SILVER AND GOLD NANOPARTICLES: A SIMPLE METHOD TO INTRODUCE NANOTECHNOLOGY INTO TEACHING LABORATORIES. A new practical experiment involving silver and gold nanoparticle syntheses was introduced in an inorganic chemistry laboratory course for undergraduate students at the Institute of Chemistry, UNICAMP. The nanoparticles were synthesized by the reduction of silver nitrate and tetrachloroauric acid with sodium borohydride and sodium citrate in an aqueous medium. Stabilities of the suspensions were tested using several different reactants including sodium chloride, polyvinylpyrrolidone, polyvinyl alcohol and cistamine. Changes in optical properties were observed by electronic spectra and also by transmission electronic microscopy, which also yielded data for estimating particle size.3591872U18

Activation profile of pro-inflammatory cytokines in acute cardiac overload

INTRODUCTION:Pro-inflammatory cytokines have been implicated in ventricular remodeling during heart failure progression. In the present study, we investigated the effects of acute volume and RV pressure overload on biventricular hemodynamics and myocardial gene expression of IL-6 and TNF-alpha.METHODS:Male Wistar rats (n = 45) instrumented with RV and LV tip micromanometers were randomly assigned to one of three protocols: i) acute RV pressure overload (PrOv) induced by pulmonary trunk banding in order to double RV peak systolic pressure, for 120 or 360 min; ii) acute volume overload (VolOv) induced by dextran40 infusion (5 ml/h), for 120 or 360 min; iii) Sham. Free wall samples from the RV and LV were collected for mRNA quantification.RESULTS:In the RV, acute overload induced IL-6 and TNF-alpha gene expression, higher in VolOv (IL-6: + 669.7 +/- 263.4%; TNF-alpha: + 5149.9 +/- 1099.0%; 360 min) than in PrOv (IL-6: + 64.9 +/- 44.2%; TNF-alpha: + 628.1 +/- 229.3%; 360 min). In PrOv, TNF-alpha mRNA levels in the LV were increased, in the absence of ventricular overload. IL-6 and TNF-alpha mRNA levels did not correlate in the LV, while in the RV a positive correlation was found (r = 0.574; p < 0.001).CONCLUSIONS:Acute cardiac overload induces overexpression of pro-inflammatory cytokines. This gene activation is not uniform, being higher in volume overload and involving both load-dependent and load-independent mechanisms

Tuberculosis screening in patients receiving biological therapy

AIM: Biological therapies are a risk factor for tuberculosis (TB). Portuguese recommendations recommend universal baseline screening for TB before starting biologics (2006) and annually thereafter if screened negative (2012 update). The gain with re-screening remains unknown. We aimed to i)identify the risk of latent TB infection at baseline screening among patients candidates to initiate biologics ii)present follow-up results for patients receiving different biological therapies and analyse intolerance or toxicity related to preventive therapy, conversions of immunodiagnostic tests under biological therapy and development of active TB. METHODS: Patients screened for TB at a reference centre before starting biological therapy between 2008-2012 were identified. Medical files were retrospectively reviewed. Demographic data, screening and follow-up results and information on biological therapy were collected. EXCLUSION CRITERIA: unavailable information on initiation of biological therapy. RESULTS: 183 patients were included in the study, with 115 starting biological therapy. The baseline screening was positive in 52(45,2%) patients - 50(96,2%) were proposed for preventive treatment (2 had abnormal liver enzymes). Mild hepatotoxicity occurred in 4(8%) patients without need to interrupt TB prophylaxis. No cases of active TB occurred during follow-up in patients with positive baseline screening. Among the 63(54,8%) patients who screened negative, 2(3,2%) developed active TB (under infliximab and adalimumab) more than one year after initiation of biologics. 26(41,3%) patients were re-screened at the TB centre. 5(19,2%) had tuberculin skin test (TST) conversion and one concomitantly undetermined IGRA. No IGRA conversions were observed. The follow-up period was 4,0 years. TB baseline screening's negative predictive value (NPV) was 96,8% (95%CI: 89,0% to 99.5%). A low rate of re-screening was observed. CONCLUSION: The rate of latent TB at baseline screening was higher than expected. Preventive treatment was well tolerated. No patients with positive baseline screening developed active TB. Efforts should be made to raise awareness concerning the risk of TB exposure, specially considering that the active TB cases were compatible with new infection. The rate of re-screening suggests a low awareness regarding current recommendations Nation-wide studies are necessary to evaluate the efficacy of the re-screening strategy and to clarify what risk groups most benefit from it

Stepped light-induced transient measurements of photocurrent and voltage in dye-sensitized solar cells based on ZnO and ZnO:Ga

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)In order to explain the higher short-circuit current (J(sc)) with comparable open-circuit voltage (V-oc) from dye-sensitized solar cells (DSCs) based on gallium-modified ZnO (ZnO:Ga) porous electrodes, the diffusion coefficient (D) and electron lifetime (tau) in DSCs with and without Ga-modified ZnO were studied by stepped light-induced transient measurements of photocurrent and voltage. In comparison to DSCs based on ZnO electrodes, the ZnO:Ga-based solar cells provided lower D and higher tau values. The results were interpreted according to the transport-limited recombination model, where the Ga modification induced a higher density of intraband charge traps. At matched electron densities, a decrease in V-oc from DSCs based on ZnO:Ga was observed, suggesting a positive shift of the ZnO:Ga conduction band edge. The higher J(sc) can be explained by the positive shift of the ZnO:Ga conduction band edge in addition to the increased roughness factor of the electrode due to the Ga modification. (C) 2009 American Institute of Physics. [doi:10.1063/1.3226073]1066Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)RenamiConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Endogenous production of ghrelin and beneficial effects of its exogenous administration in monocrotaline-induced pulmonary hypertension

We investigated the endogenous production of ghrelin as well as cardiac and pulmonary vascular effects of its administration in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). Adult Wistar rats randomly received a subcutaneous injection of MCT (60 mg/kg) or an equal volume of vehicle. One week later, animals were randomly assigned to receive a subcutaneous injection of ghrelin (100 mug/kg bid for 2 wk) or saline. Four groups were analyzed: normal rats treated with ghrelin (n = 7), normal rats injected with saline (n = 7), MCT rats treated with ghrelin (n = 9), and MCT rats injected with saline (n = 9). At 22-25 days, right ( RV) and left ventricular (LV) pressures were measured, heart and lungs were weighted, and samples were collected for histological and molecular analysis. Endogenous production of ghrelin was almost abolished in normal rats treated with ghrelin. In MCT-treated animals, pulmonary expression of ghrelin was preserved, and RV myocardial expression was increased more than 20 times. In these animals, exogenous administration of ghrelin attenuated PH, RV hypertrophy, wall thickening of peripheral pulmonary arteries, and RV diastolic disturbances and ameliorated LV dysfunction, without affecting its endogenous production. In conclusion, decreased tissular expression of ghrelin in healthy animals but not in PH animals suggests a negative feedback in the former that is lost in the latter. A selective increase of ghrelin mRNA levels in the RV of animals with PH might indicate distinct regulation of its cardiac expression. Finally, ghrelin administration attenuated MCT-induced PH, pulmonary vascular remodeling, and RV hypertrophy, indicating that it may modulate PH

The effects of CdSe incorporation into bulk heterojunction solar cells

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Hybrid solar cells based on CdSe nanoparticles and a PPV-type polymer containing fluorene and thiophene units (PFT) were investigated. The CdSe/PFT devices showed very low photocurrent and fill factor values, which was attributed to the poor charge transport in the TOPO-capped CdSe nanoparticle phase. Thus, ternary systems based on mixtures of PFT/CdSe and the fullerene derivative PCBM were investigated. The CdSe: PCBM ratio was varied, and nanoparticles with different sizes were also used. It was observed that for the optimized composition of 20 wt% PFT + 40 wt% CdSe + 40 wt% PCBM the devices presented higher photocurrents and efficiencies. The photophysical and electrochemical properties and microscopy images (AFM and HRTEM) of the ternary systems were systematically investigated to elucidate the mechanism of action of the inorganic nanoparticles in these ternary hybrid devices.202348454853Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/56924-0

Usefulness of Tissue Doppler Imaging to Predict Arrhythmic Events in Adults with Repaired Tetralogy of Fallot

INTRODUCTION: Adults with repaired tetralogy of Fallot (TOF) may be at risk for progressive right ventricular (RV) dilatation and dysfunction, which is commonly associated with arrhythmic events. In frequently volume-overloaded patients with congenital heart disease, tissue Doppler imaging (TDI) is particularly useful for assessing RV function. However, it is not known whether RV TDI can predict outcome in this population. OBJECTIVE: To evaluate whether RV TDI parameters are associated with supraventricular arrhythmic events in adults with repaired TOF. METHODS: We studied 40 consecutive patients with repaired TOF (mean age 35 +/- 11 years, 62% male) referred for routine echocardiographic exam between 2007 and 2008. The following echocardiographic measurements were obtained: left ventricular (LV) ejection fraction, LV end-systolic volume, LV end-diastolic volume, RV fractional area change, RV end-systolic area, RV end-diastolic area, left and right atrial volumes, mitral E and A velocities, RV myocardial performance index (Tei index), tricuspid annular plane systolic excursion (TAPSE), myocardial isovolumic acceleration (IVA), pulmonary regurgitation color flow area, TDI basal lateral, septal and RV lateral peak diastolic and systolic annular velocities (E' 1, A' 1, S' 1, E' s, A' s, S' s, E' rv, A' rv, S' rv), strain, strain rate and tissue tracking of the same segments. QRS duration on resting ECG, total duration of Bruce treadmill exercise stress test and presence of exercise-induced arrhythmias were also analyzed. The patients were subsequently divided into two groups: Group 1--12 patients with previous documented supraventricular arrhythmias (atrial tachycardia, fibrillation or flutter) and Group 2 (control group)--28 patients with no previous arrhythmic events. Univariate and multivariate analysis was used to assess the statistical association between the studied parameters and arrhythmic events. RESULTS: Patients with previous events were older (41 +/- 14 vs. 31 +/- 6 years, p = 0.005), had wider QRS (173 +/- 20 vs. 140 +/- 32 ms, p = 0.01) and lower maximum heart rate on treadmill stress testing (69 +/- 35 vs. 92 +/- 9%, p = 0.03). All patients were in NYHA class I or II. Clinical characteristics including age at corrective surgery, previous palliative surgery and residual defects did not differ significantly between the two groups. Left and right cardiac chamber dimensions and ventricular and valvular function as evaluated by conventional Doppler parameters were also not significantly different. Right ventricular strain and strain rate were similar between the groups. However, right ventricular myocardial TDI systolic (Sa: 5.4+2 vs. 8.5 +/- 3, p = 0.004) and diastolic indices and velocities (Ea, Aa, septal E/Ea, and RV free wall tissue tracking) were significantly reduced in patients with arrhythmias compared to the control group. Multivariate linear regression analysis identified RV early diastolic velocity as the sole variable independently associated with arrhythmic history (RV Ea: 4.5 +/- 1 vs. 6.7 +/- 2 cm/s, p = 0.01). A cut-off for RV Ea of < 6.1 cm/s identified patients in the arrhythmic group with 86% sensitivity and 59% specificity (AUC = 0.8). CONCLUSIONS: Our results suggest that TDI may detect RV dysfunction in patients with apparently normal function as assessed by conventional echocardiographic parameters. Reduction in RV early diastolic velocity appears to be an early abnormality and is associated with occurrence of arrhythmic events. TDI may be useful in risk stratification of patients with repaired tetralogy of Fallot